Updated on 2022/08/07

ICHIMURA, Shingo

Affiliation
Affiliated organization, Research Innovation Center
Job title
Professor(without tenure)

• 大阪大学   工学博士

### Research Experience

• 2018.04
-
Now

Waseda University   Center for Research Strategy   Professor

• 2014.07
-
2018.03

Nagoya University   Innovation Strategy Office Science   Director / Professor

• 2012.04
-
2014.06

National Institute of Advanced Industrial Science and Technology

• 2007.02
-
2012.03

National Institute of Advanced Industrial Science and Technology

• 2004.04
-
2007.02

National Institute of Advanced Industrial Science and Technology

• 2002.04
-
2004.03

National Institute of Advanced Industrial Science and Technology

• 2001.04
-
2002.03

National Institute of Advanced Industrial Science and Technology

• 1998.01
-
2001.03

工業技術院 電子技術総合研究所 極限技術部 総括主任研究官

• 1993.04
-
1997.12

工業技術院 電子技術総合研究所 極限技術部 表面制御研究室長

• 1985.10
-
1993.03

工業技術院 電子技術総合研究所 極限技術部 主任研究官

• 1982.04
-
1985.09

工業技術院 電子技術総合研究所 極限技術部 研究員

### Research Areas

• Thin film/surface and interfacial physical properties

### Papers

•   2020 ( 10 ) 366 - 373  2020.10

• Development of standards for reliable surface analyses by ISO technical committee 201 on surface chemical analysis

C. J. Powell, R. Shimizu, K. Yoshihara, S. Ichimura

Surface Interface Anal   47   127-134  2015  [Refereed]

View Summary

The need for reliable surface analyses together with quality-management requirements for analytical laboratories led the Interna-tional Organization for Standardization (ISO) to form its Technical Committee (TC) 201 on Surface Chemical Analysis in 1991. This article describes the organization of TC 201, the strategies that have been found useful for identifying and assessing possible projects for new international standards, and the 57 international standards and other documents prepared to date by TC 201. Standards have now been developed for Auger-electron spectroscopy, glow-discharge spectroscopy, various types of scanning probe microscopy, secondary-ion mass spectrometry, sputter-depth profiling, total-reflection X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and X-ray reflectometry. In addition, standards have been developed with definitions of terms used in surface chemical analysis; the handling, preparation of specimens for surface analysis; information and data-transfer formats; and methods for determining the lateral resolution of beam-based methods of surface analysis.

• これからの公的研究機関の在り方 : 産総研を事例として

一村 信吾

應用物理   82 ( 8 ) 672 - 673  2013.08  [Refereed]  [Invited]

• ICHIMURA Shingo

tits   18 ( 9 ) 9_67 - 9_67  2013

• ICHIMURA Shingo

Synthesiology English edition   6 ( 2 ) 136 - 136  2013

• ICHIMURA Shingo

Journal of the Vacuum Society of Japan   56 ( 7 ) 249 - 251  2013  [Refereed]

• Emission characteristics of a charged-droplet beam source using vacuum electrospray of an ionic liquid

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Shingo Ichimura

SURFACE AND INTERFACE ANALYSIS   45 ( 1 ) 517 - 521  2013.01  [Refereed]

View Summary

To develop an ion source capable of producing a charged-droplet beam at higher current density with a smaller beam spot size, beam characteristics of electrosprayed charged particles were investigated. A quaternary ammonium ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl) amide (DEME-TFSA), was tested in vacuum around 10(-5) Pa. A hysteresis behavior in the electrosprayed current was observed when the capillary voltage was changed. The m/z values of generated charged droplets decreased with decreasing flow rate and increasing capillary voltage and temperature. Average masses and charge numbers of the charged droplets as well as projectile energy per nucleon were estimated on the basis of the experimental results. Copyright (C) 2012 John Wiley & Sons, Ltd.

• AIST as a Platform for Full Research - From investigation and discovery of seed technologies to standardization

Shingo Ichimura

AIST Today (International Edition)   ( 46 ) 2 - 4  2012.12  [Refereed]

• ICHIMURA Shingo

Oyo Buturi   81 ( 8 ) 649 - 655  2012.08  [Refereed]  [Invited]

View Summary

<p>The international standardization of nanotechnology is carried out with special focus on the structure, scope, and activities of ISO (International Organization for Standardization)/TC (Technical Committee) 229. Note that the TC has already published 22 standard documents, and JISC (Japanese Industrial Standards Committee) has contributed greatly to the characterization of single- and multi-wall carbon nanotubes, which is the first target of ISO/TC 229/Working Group 2 on measurement and characterization. In addition, the standardization of the AFM probe characterization technique together with the development of an AFM probe characterizer is carried out as a typical example of the comprehensive promotion of both R&D and standardization. Note also that the contribution to the standardization and authentication of new technologies is one of the future targets of JSAP activities.</p>

• Component analysis of a mixed beam generated by vacuum electrospray of an ionic liquid

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Shingo Ichimura

JOURNAL OF APPLIED PHYSICS   111 ( 6 )  2012.03  [Refereed]

View Summary

Vacuum electrospray of a quaternary ammonium ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl) amide (DEME-TFSA), was investigated to develop a primary ion source for secondary ion mass spectrometry (SIMS). Since the ionic liquid contains many methyl and ethyl groups as well as protons, its beam is expected to efficiently produce protonated molecules for SIMS analysis of organic materials. Experimental results showed that the beam consisted of charged particles of m/z about 1000 and charged droplets of m/z > 10(5). The current components of both the charged particles and droplets changed with the applied voltage and the flow rate of the ionic liquid. With decreasing flow rate, the current component of the charged droplets increased, whereas that of the charged particles decreased. The m/z values of the charged droplets diminished with decreasing flow rate and increasing capillary voltage. In addition to masses and charge numbers, the numbers of the charged droplets and the charged particles were estimated. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3693558]

• Beam Characteristics of Positively and Negatively Charged Droplets Generated by Vacuum Electrospray of an Ionic Liquid

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   51 ( 3 ) 36701 - 036701-8  2012.03  [Refereed]

View Summary

To develop a vacuum-electrospray beam source for secondary ion mass spectrometry (SIMS), beam characteristics of charged droplets electrosprayed in vacuum were investigated in the negative-ion mode as well as the positive-ion mode. A quaternary ammonium ionic liquid was tested. Experimental results showed that there are differences as well as similarities between the positive-ion mode and the negative-ion mode. Beam current changed greatly with capillary voltage and the flow rate of the ionic liquid. Transient response analysis showed that the vacuum electrospray generated a mixed beam consisting of charged particles of smaller m/z values (m/z similar to 10(3)) and charged droplets of larger m/z values (m/z similar to 10(5) to 10(6)). It turned out that the m/z values of the charged droplets diminished with increasing capillary voltage. Using a three-dimensional positioning stage, the capillary position dependence on the beam characteristics was measured. It proved to be of great importance to align the central axis of a capillary with those of apertures in order to maximize the current component of the charged droplets of the larger m/z values and minimize the ratio of the current component of the smaller m/z values. A high alignment accuracy proved to be required at small gap lengths between a capillary tip and a counter electrode. (C) 2012 The Japan Society of Applied Physics

• ICHIMURA Shingo

Synthesiology   5 ( 3 ) 221 - 221  2012

• ICHIMURA Shingo

Synthesiology English edition   5 ( 3 ) 227 - 227  2012

• AFM Tip Characterizer fabricated by Si/SiO<inf>2</inf> multilayers

Hisataka Takenaka, Masatoshi Hatayama, Hisashi Ito, Tadayuki Ohchi, Akio Takano, Satoru Kurosawa, Hiroshi Itoh, Shingo Ichimura

e-Journal of Surface Science and Nanotechnology   9   293 - 296  2011.07  [Refereed]

View Summary

An atomic force microscopy (AFM) tip characterizer with measurement ranges from 7.7 nm to 131 nm was developed using Si/SiO2 multilayers. This characterizer was constructed with isolated line structures and comb- shaped trench structures. The shape of a standard Si AFM tip was estimated using this characterizer. The result shows that this Si/SiO2 multilayer-type tip characterizer has good potential for the characterization of AFM tips with a fine radius. ©2011 The Surface Science Society of Japan (http://www.sssj.org/ejssnt.

• Characteristics of a charged-droplet beam generated by vacuum electrospray of an ionic liquid

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Taisuke Nakanaga, Shingo Ichimura

CHEMICAL PHYSICS LETTERS   501 ( 4-6 ) 335 - 339  2011.01  [Refereed]

View Summary

To develop a cluster ion beam source for secondary ion mass spectrometry (SIMS), beam characteristics of charged droplets electrosprayed in a vacuum were investigated using a room-temperature molten salt (i.e., an ionic liquid). A target current exceeding 200 nA was produced at a capillary voltage of 1.5 kV even with a low flow rate of 0.05 mu L/min. Efficiency of beam generation varied with increasing capillary voltage and flow rate. Additionally, m/z values of emitted charged particles were investigated by a time-of-flight technique. In addition to masses and charge numbers, radii of the charged droplets were examined. (C) 2010 Elsevier B.V. All rights reserved.

• Time-of-Flight secondary ion mass spectrometry (TOF-SIMS) using the metal-cluster-complex primary ion of Ir-4(CO)(7)(+)

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Atsushi Suzuki, Taisuke Nakanaga, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura

SURFACE AND INTERFACE ANALYSIS   43 ( 1-2 ) 245 - 248  2011.01  [Refereed]

View Summary

An orthogonal acceleration Time-of-Flight Secondary Ion Mass Spectrometer (TOF-SIMS) system has been developed with a metal-cluster-complex ion source. The ion source can produce ion beams of massive molecules called metal-cluster-complexes such as Ir-4(CO)(12), which has a molecular weight higher than 1000 u. Using the system, TOF-SIMS of a contaminated silicon substrate and a room temperature molten salt (i.e. an ionic liquid) was performed. The ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, which has a molecularweight of 426 u, consists of a polyatomic cation, [C8H20ON](+), and a polyatomic anion, [C2F6NO4S2](-). During SIMS analysis, an analytical sample was bombarded with a continuous primary ion beam of either Ir-4(CO)(7)(+) or Ar+ in a beam energy of 10 keV at an incident angle of 45 degrees. It was confirmed that the use of Ir-4(CO)(7)(+) ions enhanced secondary ion intensity compared with that of Ar+ ions. Also, experimental results showed that the bombardment of Ir-4(CO)(7)(+) caused less fragmentation. In the case of the ionic liquid, cation-attached ionic-liquidmolecules were observed in addition to the cation of the ionic liquid. Copyright (C) 2010 John Wiley & Sons, Ltd.

• Development of Si/SiO2 multilayer type AFM tip characterizers

H. Takenaka, M. Hatayama, H. Itoh, T. Ochiai, A. Takano, S. kurosawa, H. Itoh, S. Ichimura

J. Surf. Anal.   17   264-268  2011  [Refereed]

• FUJIWARA Yukio, NONAKA Hidehiko, SAITO Naoaki, SUZUKI Atsushi, ITOH Hiroshi, FUJIMOTO Toshiyuki, KUROKAWA Akira, ICHIMURA Shingo, TOMITA Mitsuhiro

Hyomen Kagaku   31 ( 11 ) 593 - 598  2010.11  [Refereed]  [Invited]

View Summary

Metal cluster complexes are chemically-synthesized organometallic compounds, which have a wide range of chemical compositions with high molecular weight. Using a metal-cluster-complex ion source, sputtering characteristics of a silicon substrate bombarded with normally incident Ir4(CO)7+ ions were investigated. Experimental results showed that the sputtering yield at 10 keV was 36, which is higher than that with Ar+ ions by a factor of 24. Further, secondary ion mass spectrometry (SIMS) of boron-delta-doped silicon samples and organic films of poly (methyl methacrylate) (PMMA) was performed. Using the Ir4(CO)7+ ion beam, the depth resolution of 0.9 nm was obtained at 5keV, 45o with oxygen flooding of 1.3&times;10&minus;4 Pa. Additionally, it was confirmed that Ir4(CO)7+ ion beams significantly enhanced secondary ion intensity in high-mass range.

• A new cluster-ion-beam source for secondary ion mass spectrometry (SIMS) using the electrospray of a pure ionic liquid under high vacuum

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Taisuke Nakanaga, Shingo Ichimura

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   268 ( 11-12 ) 1938 - 1941  2010.06  [Refereed]

View Summary

Electrospray characteristics were studied using a pure room-temperature molten salt (i.e., an ionic liquid) at pressures around 10(-5) Pa as well as at atmospheric pressure. The ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide was tested, which has negligible vapor pressure and high conductivity. During electrospray, the ionic liquid was introduced at a constant flow rate into a stainless-steel capillary (i.d. 30 mu m). It was demonstrated that stable electrosprayed currents exceeding +/-1 mu A were continuously produced in both positive and negative modes. The electrosprayed currents in a high vacuum were twice those at atmospheric pressure. It was found that gas pressure rose slightly with increasing electrosprayed currents. Residual gas analysis revealed that gas component at negative mode was different from that at positive mode. Experimental results indicate that vacuum electrospray of pure ionic liquids is applicable to a massive-cluster beam source for SIMS. (C) 2010 Elsevier B.V. All rights reserved.

• Current activities of ISO TC229/WG2 on purity evaluation and quality assurance standards for carbon nanotubes

Shingo Ichimura

ANALYTICAL AND BIOANALYTICAL CHEMISTRY   396 ( 3 ) 963 - 971  2010.02  [Refereed]

View Summary

The current standardization activities of ISO ( International Organization for Standardization) TC229 on "Nano-technology" are introduced with focus on the work of WG2 ( Working Group 2) for "measurement and characterization". Seven project groups of WG2 are actively preparing standard protocols ( technical specifications) for characterization of single-wall carbon nanotubes (SWCNTs) by measurement methods such as TEM (transmission electron microscopy), SEM (scanning electron microscopy), EDX (energy-dispersive X-ray analysis), UV-Vis-NIR (ultraviolet-visible-near infrared) absorption spectroscopy, NIR-photoluminescence spectroscopy, EGA (evolved gas analysis)- GC-MS (gas chromatography-mass spectrometry), TGA (thermogravimetric analysis), and Raman spectroscopy; this work is described. The features of purity evaluation of SWCNTs by these methods are also briefly described and compared. Also described are two project groups of WG2 that are preparing standard protocols for characterization of multiwall CNTs (MWCNTs), aiming at the purity control by measurement of moisture content, ash content, metallic constituents, volatile content, polyaromatic hydrocarbon content, and carbon materials excluding MWCNTs. Other important properties for characterization of MWCNT, for example disorder, burning property, stacking nature, length, morphology, and inner/outer diameter, etc., are also mentioned. Finally, the importance and urgency of standardization for potential risk assessment of CNTs is briefly described, and current joint activity of ISO TC229 WG2 and WG3 for physicochemical characterization of engineered nanoscale materials for toxicological assessment is introduced.

• Evaluation of Outermost Surface Temperature of Silicon Substrates during UV-Excited Ozone Oxidation at Low Temperature

Naoto Kameda, Tetsuya Nishiguchi, Yoshiki Morikawa, Mitsuru Kekura, Ken Nakamura, Tomoharu Ushiyama, Hidehiko Nonaka, Shingo Ichimura

ANALYTICAL SCIENCES   26 ( 2 ) 273 - 276  2010.02  [Refereed]

View Summary

Using ultraviolet (UV)-excited ozone gas, we prepared high-quality SiO2 films that can be used as gate dielectric films on poly-silicon or silicon wafers without sample heating. The UV-excited ozone gas was generated by UV irradiation of highly concentrated ozone gas. During the UV-excited ozone process, UV light irradiates the sample surface directly through the ozone gas. Then, the temperature at the sample surface is increased by UV-light absorption at the surface. Estimation of this surface temperature is important for understanding the oxidation mechanism. We estimated the surface temperature obtained during UV irradiation to be about 300 degrees C by investigating the temperature dependence of the oxidation rate for oxygen gas. We have previously determined that almost no thermal decomposition of ozone gas occurs at this temperature, and that oxygen gas does not oxidize the Si substrate. Therefore, we concluded that the only oxidation species in the UV-excited ozone process is UV-excited ozone O(D-1).

• Ion Beam Generation from an Electrolyte Solution Containing Polyatomic Cations and Anions for Secondary Ion Mass Spectrometry

Yukio Fujiwara, Kouji Watanabe, Naoaki Saito, Hidehiko Nonaka, Atsushi Suzuki, Taisuke Nakanaga, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 12 ) 126005 - 126005-10  2009.12  [Refereed]

View Summary

A solution-type ion beam source was fabricated to utilize polyatomic anions as well as polyatomic cations that are stable in solutions. The ion source consists of an electrospray section at atmospheric pressure and a vacuum section with a differential pumping system. To demonstrate the beam generation of cations or anions, ethanol solution containing a room-temperature molten sail (i.e., an ionic liquid) was tested. The ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, consists of a polyatomic cation, [C(8)H(20)ON](+), and a polyatomic anion, [C(2)F(6)NO(4)S(2)](-). Ions produced at atmospheric pressure were passed through an aperture into a vacuum chamber and then transported to a target. The effects of the aperture dimensions were investigated in the range from 50 to 200 pm in diameter and 0.25 to 1 mm in thickness. The ratio of current passing through the aperture into the vacuum chamber to the total electrosprayed current was on the order of 10(-3) to 10(-5). The ratio increased with increasing aperture diameter. A reduction in the aperture thickness also improved the ratio. Beam current increased with applied voltage in both positive-ion and negative-ion modes. It was demonstrated that stable negative-ion beams as well as positive-ion beams on the order of pA were produced. (C) 2009 The Japan Society of Applied Physics

• Metal cluster complex primary ion beam source for secondary ion mass spectrometry (SIMS)

Yukio Fujiwara, Kouji Watanabe, Hidehiko Nonaka, Naoaki Saito, Atsushi Suzuki, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura

VACUUM   84 ( 5 ) 544 - 549  2009.12  [Refereed]

View Summary

To develop a solution-type ion beam source utilizing a wide variety of metal cluster complexes that are stable only in organic solvents, we have investigated an electrospray method for transferring ions from solutions to gas phase. As initial experiments, we have studied electrospray characteristics of ethanol solutions containing a room-temperature molten salt (i.e., an ionic liquid) and acetic acid as alternatives to solutions of metal Cluster complexes. in electrospray experiments, we used a stainless-steel capillary with an inner diameter of 30 mu m. Experimental results showed that electrosprayed currents increased with applied voltage in both positive-ion and negative-ion modes. In addition to positive currents, stable negative currents were also confirmed to be produced. Current exceeding 250 nA was produced at 2 kV with a How rate of 2 mu L/min at a concentration of 1 x 10(-3) mol/L. It was confirmed that several nA out of electrosprayed currents were delivered through an orifice (120 mu m internal diameter) into a vacuum chamber. Experimental results indicate that the electrospray method seems to be applicable to an ion beam source for utilizing massive metal cluster complexes in solutions. (C) 2009 Elsevier Ltd. All rights reserved.

• Improvement in Chemical-Vapor-Deposited-SiO2 Film Properties by Annealing with UV-Light-Excited Ozone

Tetsuya Nishiguchi, Shigeru Saito, Naoto Kameda, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 11 ) 116509 - 116509-5  2009.11  [Refereed]

View Summary

Ultraviolet-enhanced, highly concentrated (>90 vol%) ozone gas annealing was carried out at 200 degrees C to fabricate as-deposited tetraethoxysilane chemical vapor deposited SiO2 film (TEOS-CVD films) applicable as a gate dielectric material for thin-film transistors As a result of this annealing, the leakage current density, fixed charge density, and dielectric constant of the films decreased to those of thermally grown silicon oxide The relative dielectric constant, for example, was reduced from 5.4 to 4 0 The films' resistance to wet-etching solution was also improved, particularly within the region located 3-5 rim from the films' surface. In the region, the reduction in the amount of the excess positive charges of Si and the increase in the density of an ideal Si-O bonding network were confirmed from X-ray photoelectron spectroscopy measurements. These results suggest that oxygen atoms are incorporated into the film, while impurities contained in the film such as OH are out gassed by the diffusion of oxygen atoms generated from the photo dissociation of ozone in the gas phase. The annealing effects with and without oxygen atom supply were compared and the mechanism of the annealing is discussed (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.116509

• Advantage of Highly Concentrated (>= 90%) Ozone for Chemical Vapor Deposition SiO2 Grown under 200 degrees C Using Hexamethyldisilazane and Ultraviolet Light Excited Ozone

Naoto Kameda, Tetsuya Nishiguchi, Yoshiki Morikawa, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 5 )  2009.05  [Refereed]

View Summary

We have compared the UV-light-excited ozone chemical vapor deposition (CVD) process conditions and the film quality for the cases where either highly concentrated (>= 90%: HC) or 7% ozone and either hexamethyldisilazane (HMDS) or tetraethoxysilane (TEOS) are used. The SiO2 film deposited using HMDS and UV-excited HC ozone with an optimized flow rate has the highest quality in terms of leakage current density, etching rate, and deposition rate which are comparable or superior to those of the conventional thermal TEOS SiO2 grown at 620 degrees C. These results lead to a conclusion that it is preferable to use HC ozone for UV-light-excited-ozone CVD to deposit the high quality SiO2 films at a practical rate at a temperature as low as 200 degrees C. (C) 2009 The Japan Society of Applied Physics

• Silicon oxidation by ozone

Christian K. Fink, Ken Nakamura, Shingo Ichimura, Stephen J. Jenkins

JOURNAL OF PHYSICS-CONDENSED MATTER   21 ( 18 )  2009.05  [Refereed]

View Summary

Understanding the oxidation of silicon has been an ongoing challenge for many decades. Ozone has recently received considerable attention as an alternative oxidant in the low temperature, damage-free oxidation of silicon. The ozone-grown oxide was also found to exhibit improved interface and electrical characteristics over a conventionally dioxygen-grown oxide. In this review article, we summarize the key findings about this alternative oxidation process. We discuss the different methods of O-3 generation, and the advantages of the ozone-grown Si/SiO2 interface. An understanding of the growth characteristics is of utmost importance for obtaining control over this alternative oxidation process.

• Advantage of Highly Concentrated (>= 90%) Ozone for Chemical Vapor Deposition SiO2 Grown under 200 degrees C Using Hexamethyldisilazane and Ultraviolet Light Excited Ozone

Naoto Kameda, Tetsuya Nishiguchi, Yoshiki Morikawa, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 5 ) 05DB01 - 05DB01-4  2009.05

View Summary

We have compared the UV-light-excited ozone chemical vapor deposition (CVD) process conditions and the film quality for the cases where either highly concentrated (>= 90%: HC) or 7% ozone and either hexamethyldisilazane (HMDS) or tetraethoxysilane (TEOS) are used. The SiO2 film deposited using HMDS and UV-excited HC ozone with an optimized flow rate has the highest quality in terms of leakage current density, etching rate, and deposition rate which are comparable or superior to those of the conventional thermal TEOS SiO2 grown at 620 degrees C. These results lead to a conclusion that it is preferable to use HC ozone for UV-light-excited-ozone CVD to deposit the high quality SiO2 films at a practical rate at a temperature as low as 200 degrees C. (C) 2009 The Japan Society of Applied Physics

• Characterizing Atomic Force Microscopy Tip Shape in Use

Chunmei Wang, Hiroshi Itoh, Jielin Sun, Jun Hu, Dianhong Shen, Shingo Ichimura

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   9 ( 2 ) 803 - 808  2009.02  [Refereed]

View Summary

A new tip characterizer based on the fabrication of multilayer thin films for atomic force microscopy (AFM) was developed to analyze the effective tip shape while in use. The precise structure of this tip characterizer was measured by transmission electron microscopy. Four different types of commercial tips with various radii were characterized by the tip characterizer and by conventional scanning electron microscopy (SEM). The results were compared to obtain a relationship between the actual and effective tip shapes. A quantitative analysis was performed of apex radii measured from line profiles of comb-shaped patterns and nanometer-scale knife-edges without the problem of edge uncertainty in the SEM image. Degradation of the AFM tip induced by electron-beam irradiation was studied by using SEM and the tip characterizer. A potential technique for fabricating symmetric AFM tips based on irradiation by an electron beam and a quantitative analysis of changing the tip apex in SEM were examined with AFM using the tip characterizer.

• Fujimoto Toshiyuki, Ichimura Shingo

KENBIKYO   44 ( 3 ) 185 - 190  2009

View Summary

<p>Current standardization activities relating to the measurement and characterization of nanomaterials and nanostructures are described. The working items which have been discussed by WG2 of ISO TC229 on Nanotechnology are explained together with the scope and stracture of ISO TC229. Standardization strategy at the WG2 is also discribed.</p>

• Current standardization activities for the measurement and characterization of nanomaterials and structures

Shingo Ichimura, Hiroshi Itoh, Toshiyuki Fujimoto

Journal of Physics: Conference Series   159  2009  [Refereed]

View Summary

Current standardization activities relating to the measurement and characterization of nanomaterials and nanostructures are described. The working items relating to single-wall and multiwall carbon nanotubes, which have been discussed by WG2 of ISO TC229 on Nanotechnology, are explained together with the social requests for standardization and the scope and structure of ISO TC229. In addition, the standardization of AFM probe characterization, which is under discussion at ISO TC201 (Surface Chemical Analysis)/SC9 (Scanning Probe Microscopy), is introduced. A new type of probe characterizer necessary for the precise measurement of probe shape is described, and the merit and utility of a probe-shape function that gives the relation between the probe length and width are also explained. © 2009 IOP Publishing Ltd.

• Factorial analysis of cluster-SIMS depth profiling using metal-cluster-complex ion beams

Yukio Fujiwara, Kouji Kondou, Kouji Watanabe, Hidehiko Nonaka, Naoaki Saito, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

APPLIED SURFACE SCIENCE   255 ( 4 ) 1338 - 1340  2008.12  [Refereed]

View Summary

A Ir(4)(CO)(7)(+) primary ion beam, at energies from 2.5 keV to 10 keV, was used to profile boron-delta layers in Si to investigate the influences of atomic mixing and surface roughness on the degradation of depth resolution. Factorial analyses using the mixing-roughness-information (MRI) model indicated that the influence of the mixing increased as beam energy was reduced below 5 keV in the case of oxygen flooding. It was confirmed that the magnitude of the MRI surface roughness was different from that of the AFM surface roughness. The discrepancy in the magnitude of roughness was examined by considering the difference in sputtering depth as well as the definition of the MRI surface roughness. (C) 2008 Elsevier B.V. All rights reserved.

• Cluster SIMS using metal cluster complex ions

Yukio Fujiwara, Kouji Kondou, Yoshikazu Teranishi, Kouji Watanabe, Hidehiko Nonaka, Naoaki Saito, Hiroshi Itoh, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

APPLIED SURFACE SCIENCE   255 ( 4 ) 916 - 921  2008.12  [Refereed]

View Summary

Metal cluster complexes are chemically synthesized organometallic compounds, which have a wide range of chemical compositions with high molecular weight. Using a metal cluster complex ion source, sputtering characteristics of silicon bombarded with normally incident Ir(4)(CO)(7)(+) ions were investigated. Experimental results showed that the sputtering yield at 10 keV was 36, which is higher than that with Ar(+) ions by a factor of 24. In addition, secondary ion mass spectrometry (SIMS) of boron-delta-doped silicon samples and organic films of poly(methyl methacrylate) (PMMA) was performed. Compared with conventional O(2)(+) ion beams, Ir(4)(CO)(7)(+) ion beams improved depth resolution by a factor of 2.5 at the same irradiation conditions; the highest depth resolution of 0.9 nm was obtained at 5 keV, 45 degrees with oxygen flooding of 1.3 x 10 (4) Pa. Furthermore, it was confirmed that Ir(4)(CO)(7)(+) ion beams significantly enhanced secondary ion intensity in high-mass region. (C) 2008 Elsevier B. V. All rights reserved.

• Photochemical reaction of ozone and 1,1,1,3,3,3-hexamethyldisilazane: Analysis of the gas reaction between precursors in a photochemical vapor deposition process

Ken Nakamura, Hidehiko Nonaka, Naoto Kameda, Tetsuya Nishiguchi, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 9 ) 7349 - 7355  2008.09  [Refereed]

View Summary

The photochemical reaction of 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and ozone (O(3)) in the gas phase was analyzed as the side reaction in the photochemical vapor deposition (photo-CVD) process irradiated by ultraviolet light; the analysis was conducted by Fourier-transform infrared absorption spectroscopy (photo-CVD) and mass spectrometry (MS). The final products of this photochemical reaction between HMDS and O(3) are CO(2), N(2), and H(2)O, although this reaction is initiated at the Si-N-Si bond of HMDS with O(3) and ultraviolet (UV) light, thus producing, as a reaction intermediate, a compound with carbonyl and/or carboxylic group followed by Si-N-Si scission.

• Geometric characterization of carbon nanotubes by atomic force microscopy in conjunction with a tip characterizer

Chunmei Wang, Hiroshi Itoh, Yoshikazu Homma, Jielin Sun, Jun Hu, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 7 ) 6128 - 6133  2008.07  [Refereed]

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An atomic force microscopy (AFM) probe tip characterizer with 14 line and space structures and two knife edges was fabricated by means of a superlattice technique. The shape of a probe tip both before and after AFM imaging was acquired by this tip characterizer with general variations < 1.5 nm; depending on imaging conditions. The geometric structures of carbon nanotubes (CNTs) on a SiO(2) substrate were studied by dynamic mode AFM in conjunction with this tip characterizer. Contact points between the tip and the CNTs were detected by observing changes in the AFM phase images. A modified CNT width correction model was established to calculate the estimated and Upper-limit widths of two CNTs. The experimental results showed that imaging under a weak attractive force was suitable for obtaining accurate CNT height measurements, whereas a weak repulsive force provided the most accurate widths. Differing heights and widths between the two CNTs suggested that one CNT was double-walled, whereas the other had more than two walls; these results agree with transmission electron microscopy (TEM) measurements of the CNTs.

• Dissociative ionization of a large molecule studied by intense phase-controlled laser fields

Hideki Ohmura, Naoaki Saito, Hidehiko Nonaka, Shingo Ichimura

PHYSICAL REVIEW A   77 ( 5 )  2008.05  [Refereed]

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We report on the dissociative ionization of a large polyatomic molecule induced by quantum control of tunneling ionization. The directionally asymmetric tunneling ionization induced by phase-controlled two-color (omega+2 omega) intense (1.0 X 10(13) W/cm(2)) laser fields with 130-fs pulses led to selective ionization of oriented molecules, which reflect the geometric nature of the highest occupied molecular orbital. We conclude that in the case of 1-iodohexane the molecular Ammosov-Delone-Krainov model for tunneling ionization is qualitatively valid even for the large polyatomic molecule, and that the nonadiabatic multielectron dynamics, which lead to fragmentation, play a much more important role in molecular cations than in neutral molecules.

• NAKAMURA Ken, NONAKA Hidehiko, KAMEDA Naoto, NISHIGUCHI Tetsuya, ICHIMURA Shingo

Journal of the Vacuum Society of Japan   51 ( 3 ) 224 - 227  2008.03  [Refereed]

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&nbsp;&nbsp;Fourier-Transformed Infrared absorption spectroscopy (FT-IR) was applied to analysis of initial photochemical reaction of ozone (O3) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature in the gas phase under the irradiation of an ultraviolet (UV) light, as the side reaction during the fabrication of a silicon oxide (SiO2) film by photo-assisted chemical vapor deposition (CVD). FT-IR spectrum indicated the photodissociation of O3 by the UV light, shown by the decreases in the intensity of peaks assigned to an O3 molecule in the spectrum. Under the confirmation of this photodissociation of an O3 molecule, while the UV light is known to induce no photochemical reaction of HMDS, FT-IR spectrum indicated the photochemical reaction of HMDS by its scission of Si-N-Si bond and formation of C=O bond and SiO2 in a mixture of O3 and HMDS gases, thus showing that direct reaction of photodissociated species from O3, possibly atomic oxygen, with HMDS.<br>

• High depth resolution SIMS analysis using metal cluster complex ion bombardment

M. Tomita, T. Kinno, M. Koike, H. Tanaka, S. Takeno, Y. Fujiwara, K. Kondou, Y. Teranishi, H. Nonaka, T. Fujimoto, A. Kurokawa, S. Ichimura

PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY   100  2008  [Refereed]

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SIMS depth profiles were measured using metal cluster complex ions of Ir-4(CO)(7)(+) as a primary ion beam in order to obtain high depth resolution. Depth resolution was evaluated as a function of primary ion species, energy and incident angle using a multiple boron delta-doped silicon sample. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same bombardment condition due to reduction of atomic mixing in the depth. The best depth resolution was 0.9 nm under the bombardment condition of 5 keV, 45 degrees with oxygen flooding, which approaches the value measured with state of the art SIMS analyses. However, depth resolution was not improved by decreasing the cluster ion energy (less than 5 keV), even though the roughness of the sputtered surface was suppressed. The limit of depth resolution improvement may be caused by a carbon cover-layer that prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion.

• Secondary-ion-mass-spectrometry depth profiling of ultra-shallow boron delta layers in silicon with massive molecular ion beam of Ir-4(CO)(7)(+)

Yukio Fujiwara, Kouji Kondou, Kouji Watanabe, Hidehiko Nonaka, Naoaki Saito, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   46 ( 11 ) 7599 - 7601  2007.11  [Refereed]

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Tetrairidium dodecacarbonyl, lr(4)(CO)(12), is a massive compound called metal cluster complex, which has a molecular weight of 1104.9. Using an lr(4)(CO)(7)(+) primary ion beam, secondary ion mass spectrometry (SIMS) of boron-delta-doped silicon samples was performed. Depth resolution, defined by 1/e decay length for the trailing edge of the boron delta layer, was investigated in the beam energy ranging from 2.5 to 10keV at an incident angle of 45 degrees. Experimental results showed that the depth resolution improved with oxygen partial pressure at a beam energy of 5 keV. It was confirmed that the depth resolution without oxygen flooding monotonically improved as beam energy decreased. Furthermore, it was found that the favorable effect of oxygen flooding on depth resolution weakened as beam energy was reduced.

• Characteristics of altered layers formed by sputtering with a massive molecular ion containing diverse elements with large mass differences

Yukio Fujiwara, Kouji Kondou, Hidehiko Nonaka, Naoaki Saito, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JOURNAL OF APPLIED PHYSICS   102 ( 7 )  2007.10  [Refereed]

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Tetrairidium dodecacarbonyl (Ir-4(CO)(12)) is an organometallic compound called metal cluster complex which has a molecular weight of 1104.9. To investigate its irradiation effect, silicon substrates sputtered with 10 keV Ir-4(CO)(7)(+) were analyzed by high resolution Rutherford backscattering spectrometry. Experimental results were examined on the basis of a conventional theory of simultaneous implantation and sputtering. The introduction of oxygen gas during sputtering proved to form a thick oxide layer in the substrate, resulting in iridium segregation at the silicon-oxide interface and carbon accumulation near the surface. It was confirmed that oxygen partial pressure significantly affected the characteristics of an altered layer beneath a sputtered surface. (C) 2007 American Institute of Physics.

• Standard materials and metrology for Nanotechnology (SMAM-2)

Shingo Ichimura, Tomizo Kurosawa, Toshiyuki Fujimoto, Hidehiko Nonaka

MEASUREMENT SCIENCE AND TECHNOLOGY   18 ( 9 )  2007.09  [Refereed]

• Beam-induced nanoscale ripple formation on silicon with the metal-cluster-complex ion of Ir-4(CO)(7)(+)

Yukio Fujiwara, Kouji Kondou, Kouji Watanabe, Hidehiko Nonaka, Naoaki Saito, Hiroshi Itoh, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   46 ( 33-35 ) L854 - L857  2007.09  [Refereed]

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The surface topography of Si(100) bombarded with 2.5-10 keV Ir-4(CO)(7)(+) at an incident angle of 45 degrees was investigated by atomic force microscopy. Experimental results showed that self-organized ripple structures with a wavelength below 30 nm were produced at a beam energy of 5 keV. It was found that the wavelength of the ripples increased with decreasing beam energy. which is different from results obtained using conventional ion beams. In addition, surface roughness proved to increase with decreasing beam energy. The phenomena were explained by considering a substantial decrease in sputtering yield and the subsequent compositional change in the target at lower-beam-energy Ir-4(CO)(7)(+) bombardment. Furthermore, the surface roughness was also confirmed to increase with increasing oxygen partial pressure.

• Observation of a Si surface sputtered by an ion irradiation system using a prototype compact cluster ion source

Yoshikazu Teranishi, Kouji Kondou, Takeshi Mizota, Yukio Fujiwara, Hidehiko Nonaka, Kazuhiro Yamamoto, Toshiyuki Fujimoto, Shingo Ichimura

SURFACE & COATINGS TECHNOLOGY   201 ( 19-20 ) 8641 - 8645  2007.08  [Refereed]

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A prototype compact cluster ion source has been developed using a metal cluster complex as a low damage-sputtering source, since clusters are said to be effective for so-called "lateral sputtering". Using a metal cluster complex ion gun the Si surface was successfully sputtered with high sputtering yield, and yet resulting in reasonably smooth surface for a sputtered depth of 10 nm.Using the prototype compact cluster ion source, an ion beam containing metal cluster complexes Of OS3(CO)(12) was generated with an acceleration energy of 10 keV and total fluence, N-CB, of 5.2 x 10(12) ions (I-ave=0.050 nA, time=278 min).From the results of AFM and SEM measurements, the sputtered Si surface was found to be reasonably smooth for a sputtering depth of similar to 10 nm. The sputtered Si portion was found to be a truncated (elliptical) cone. The volume was estimated to be 3.2 x 10(-9) cm(3), i.e., N-Si, the number of removed Si atoms was about 1.6 x 10(14). Thus the sputtering yield, N-Si/N-CB, was estimated to be as large as 30. Surface state characterization and contamination were investigated using XPS (X-ray photoelectron spectroscopy) and AES (Auger electron spectroscopy), showing there was no Os on the sputtered Si surface.These results show that this ion irradiation system using a prototype compact cluster ion source is capable of high rate sputtering resulting in a smooth sputtered surface without deposition, showing the possibility for small penetration depth leading to low damage sputtering, in other words, lateral sputtering due to simultaneous multi-atom bombardment. (C) 2007 Published by Elsevier B.V.

• Rapid oxidation of silicon using UV-light irradiation in low-pressure, highly concentrated ozone gas below 300 degrees C

Tetsuya Nishiguchi, Shigeru Saitoh, Naoto Kameda, Yoshiki Morikawa, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   46 ( 5A ) 2835 - 2839  2007.05  [Refereed]

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A low-temperature, damage-free process for growing ultrathin (<6nm) silicon dioxide NOD films was successfully developed. The excitation of low-pressure, highly concentrated 03 gas using photons with energies less than 5.6eV led to rapid growth rates of 2 and 3 nm within 1 and 5 min, respectively, even when the process temperature was as low as 200 degrees C. The enhanced oxidation rate was due to an increased supply of O(D-1) atoms at the Si surface. Transmission electron microscope images revealed that the SiO2 film formed with a uniform thickness and a smooth, distinct SiO2/Si interface. Capacitance-voltage and current-voltage measurements showed that 200 and 300 degrees C as-grown films had a satisfactorily low density of mobile ions and trap charges as well as ideal insulating properties.

• SIMS depth profile study using metal cluster complex ion bombardment

M. Tomita, T. Kinno, M. Koike, H. Tanaka, S. Takeno, Y. Fujiwara, K. Kondou, Y. Teranishi, H. Nonaka, T. Fujimoto, A. Kurokawa, S. Ichimura

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   258 ( 1 ) 242 - 245  2007.05  [Refereed]

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SIMS depth profiles using a metal cluster complex ion of Ir4(CO)(+)(7) were studied. An unusual increase of the sputtering yield under the condition of small incident angle may be attributed to the suppression of taking oxygen from flooding 0, by the formation of a carbon cover-layer derived from Ir4(CO)(+)(7) ion. Even though the roughness of the sputtered surface is small, the depth resolution was not improved by decreasing the cluster ion energy to less than 5 keV, because the carbon cover-layer prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion. (C) 2006 Elsevier B.V. All rights reserved.

• Sputtered Si surface irradiated by metal cluster complex ions such as OS3(CO)(12) and Ir-4(CO)(12)

Yoshikazu Teranishi, Kouji Kondou, Yukio Fujiwara, Hidehiko Nonaka, Toshiyuki Fujimoto, Shingo Ichimura, Misuhiro Tomita

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   257   670 - 676  2007.04  [Refereed]

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The surface sputtering of Si using a proto-type ion gun to utilize metal cluster complexes as ion source has been investigated in detail mainly using Auger spectroscopy and atomic force microscope. The Si surface was found to be successfully sputtered with a high sputtering yield and yet resulting in a reasonably smooth surface. However, the sputtered surface roughness behavior against the incident angle of the ion beam show strong dependence to the accelerating energy of the cluster ions, which could be explained by the balance between the sputtering effect and deposition of ions themselves. (c) 2007 Elsevier B.V. All rights reserved.

• Irradiation characteristics of metal-cluster-complex ions containing diverse multi-elements with large mass differences

Yukio Fujiwara, Kouji Kondou, Yoshikazu Teranishi, Hidehiko Nonaka, Naoaki Saito, Toshlyuk Fuj, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   257   653 - 657  2007.04  [Refereed]

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Tetrairidium dodecacarbonyl, Ir-4(CO)(12), is a metal cluster complex which has a molecular weight of 1104.9. Using a metal-clustercomplex ion source, the interaction between Ir-4(CO)(n)(+) ions (n = 0-12) and silicon substrates was studied at a beam energy ranging from 2 keV to 10 keV at normal incidence. By adjusting Wien-filter voltage, the influence of CO ligands was investigated. Experimental results showed that sputtering yield of silicon bombarded with Ir-4(CO)(n)(+) ions at 10 keV decreased with the number of CO ligands. In the case of 2 keV, deposition tended to be suppressed by removing CO ligands from the impinging cluster ions. The influence of CO ligands was explained by considering changes in surface properties caused by the irradiation of Ir-4(CO)(n)(+) ions. It was also found that the bombardment with Ir-4(CO)(n)(+) ions at 2.5 keV caused deposition on silicon target. (c) 2007 Elsevier B.V. All rights reserved.

• Etching-enhanced surface stress relaxation during initial ozone oxidation

Tetsuya Narushima, Masahiro Kitajima, Akiko N. Itakura, Akira Kurokawa, Shingo Ichimura, Kazushi Miki

SURFACE SCIENCE   601 ( 5 ) 1384 - 1388  2007.03  [Refereed]

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Initial oxidation via ozone on the Si(100) surface is investigated by measuring surface stress and observing atomic structure via a scanning tunneling microscopy (STM). A similar investigation is also carried out for molecular oxygen and the results are compared. As a result, monotonic increase of the surface stress to the compressive stress side is obtained up to 0.33 N/m for ozone oxidation at room temperature, while molecular oxygen shows only tiny surface stress growth. From the STM observations, it is found that the difference between ozone and molecular oxygen oxidation is the existence of surface etching. As the origin of the surface stress, therefore, the reduction of the intrinsic tensile surface stress due to the reconstructed surface by the etching process is proposed. (c) 2007 Elsevier B.V. All rights reserved.

• Reaction analysis of initial oxidation of silicon by UV-light-excited ozone and the application to rapid and uniform SiO2 film growth

Aki Tosaka, Hidehiko Nonaka, Shingo Ichimura, Tetsuya Nishiguchi

JOURNAL OF APPLIED PHYSICS   101 ( 3 )  2007.02  [Refereed]

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UV-light-excited O-3 prepared by irradiation of nearly 100% pure O-3 with a KrF excimer laser (lambda=248 nm, irradiated area=30x10 mm(2)) was utilized for low-temperature Si oxidation. The initial oxidation rate was determined, and the activation energy was shown to be almost zero (0.049 eV). To clarify the optimum oxidation conditions, the dependence of the SiO2 film growth rate on the total photon number and the photon density was investigated. The evolution of O-3 density after UV-light irradiation was experimentally measured, and the O(D-1) density change is discussed. O(D-1) density changes are successfully explained by using a second-order reaction model, indicating that a pulse supply of oxygen atoms is essential in the initial oxidation process. The uniform oxidation of 8 in. Si wafer has been carried out using a wafer-transfer type chamber by irradiating the wafer with KrF excimer laser light expanded linearly to the wafer width by a concave lens. (c) 2007 American Institute of Physics.

• Global standardization of scanning probe microscopy

Daisuke Fujita, Hiroshi Itoh, Shingo Ichimura, Tomizo Kurosawa

NANOTECHNOLOGY   18 ( 8 )  2007.02  [Refereed]

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Recent efforts to achieve global standardization of scanning probe microscopy ( SPM) including noncontact atomic force microscopy ( NC- AFM), especially through the International Organization for Standardization ( ISO) and related research, are surveyed. Since the unification of terminology for SPM is a prerequisite for standardization, it should have the first priority, followed by the unification of data management and treatment, which will enable access to and processing of SPM data collected by different types of instrument. Among the various SPM analytical methods, the dimensional metrology of SPM is regarded to be the first priority for standardization. This requires solving two basic problems: calibrating the x, y, and z coordinate axes with traceability to the SI unit of length, and eliminating the morphological artefacts caused by the shape of the probe tip. Pre- standardization efforts on restoring distorted images and characterizing the tip shape during use are discussed.

• Observation of Sputtered Si Surface Irradiated with Metal Cluster Complex Ions

Y. Teranishi, K. Kondou, H. Nonaka, Y. Fujiwara, K. Yamamoto, T. Fujimoto, A. Kurokawa, S. Ichimura

Surf. Coating Tech.   201   8641-8655  2007  [Refereed]

• High quality gate dielectric film on poly-silicon grown at room temperature using UV light excited ozone

N. Kameda, T. Nishiguchi, Y. Morikawa, M. Kekura, H. Nonaka, S. Ichimura

JOURNAL OF THE ELECTROCHEMICAL SOCIETY   154 ( 9 ) H769 - H772  2007  [Refereed]

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We have grown SiO2 films on polycrystalline Si using excited ozone produced by ultraviolet light irradiation of ozone, and characterized their electrical properties in the metal-insulator-semiconductor capacitor configuration. SiO2 films of similar to 8.5 nm thickness on poly- Si layers were grown in 60 min even at room temperature. The leakage current density across the SiO2 film fitted well the Fowler-Nordheim tunnel current behavior and breakdown occurred at above 12 MV/cm, showing that the film was of device quality. The rate of Si oxidation by excited ozone was similar for both Si (100) and Si (111) wafers, as was the interface trap density ( D-it ). These results indicate that excited ozone can form a homogenous SiO2 film on poly- silicon. We conclude that excited ozone is one of the most efficient reactive species for SiO2 film formation on poly- Si at room temperature. (c) 2007 The Electrochemical Society.

• Concentration Sensor for Hydrogen-Methane Mixed Gas Based on Quartz Oscillator

Yohei Kobayashi, Akira Kurokawa, Takichi Kobayashi, Hisao Hojo, Hidehiko Nonaka, Shingo Ichimura, Masaru Hirata

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY   2 ( 1 ) 102 - 110  2007  [Refereed]

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Quartz is used in various devices, since it can be easily vibrated by the piezoelectric effect and controlled in an electric circuit. The force, which acts on the vibrating body, follows the principles of fluid dynamics; this phenomenon is explained in detail by the Navier-Stokes equation that is a fundamental equation of motion of a flow system. The authors measured the drag acting on a vibrating body (i.e., a quartz oscillator) settled within a hydrogen-methane mixed gas. The quartz oscillator is sensitive to temperature, pressure, and viscosity. It was placed in a constant temperature bath to control the temperature accurately. A pressure gauge was also placed into the same bath, and the pressure inside the tube was controlled by using a piezo valve. This drag is measured and converted into a physical property by using an approximate solution of the Navier-Stokes equation. The drag changes depending on gas conditions, because the property of a gas differs under different conditions. If a quartz oscillator can detect this difference, it can be used as a sensor for a gas. In this study, the authors attempted to ascertain the possibility of using a quartz oscillator as a concentration sensor for a hydrogen-methane mixed gas. The large-scale project on hydrogen-methane mixed gas that has begun in Europe shows the increasing concern for devices using hydrogen-methane mixed gas among the countries because of environmental issues. Differences in the mixture ratio of the hydrogen-methane mixed gas were successfully determined by this sensor.

• Characteristics of a cluster-ion beam of a cluster-ion beam of Os-3(CO)(n)(+) (n=7 or 8) for low-damage sputtering

Yukio Fujiwara, Kouji Kondou, Yoshikazu Teranishi, Hidehiko Nonaka, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

SURFACE AND INTERFACE ANALYSIS   38 ( 12-13 ) 1539 - 1544  2006.12  [Refereed]

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A cluster-ion source has been developed to produce stable ion beams of metal-cluster-complex ions. As a metal cluster complex, triosmium dodecacarbonyl, Os-3(CO)(12), was used, which has a molecular weight of 906.7. Using the ion source, energy dependence of beam current and sputtering yield of silicon bombarded with Os-3(CO)(n)(+) (n = 7-8) were investigated at beam energies from 2 to 10 keV under the normal incidence condition. By high-resolution Rutherford backscattering spectrometry (HR-RBS), a silicon target bombarded with the normally incident Os-3(CO)(7-8)(+) ions at 10 keV with oxygen flooding at 5 x 10(-4) Pa was analyzed. The experimental results showed that the ion-beam current increased almost linearly with the acceleration voltage. It was found that the sputtering yields of silicon with O(s)3(CO)(7-8)(+) ions varied substantially with beam energy. The sputtering yield with Os-3(CO)(7-8)(+) at 10 keV was higher than that with SF5+ or Ar+ by a factor of 3-20, whereas the yield at 3 keV was lower than that with Ar+. In the case of 2 keV, deposition was found to occur on the silicon surface. The substantial variation in the sputtering yield with beam energy would arise from the lower kinetic energy of each atom constituting the metal-cluster-complex ions. From HR-RBS results, it was confirmed that the constituent atoms of the Os-3(CO)(7-8)(+) ions, Os, C, and O, were implanted into the silicon target. The observed depth profiles of Os and C atoms were in good agreement with results of TRIM simulation, while that of the O atom was significantly different from the simulation results. The depth profile of the O atom was examined in terms of oxygen diffusion and implantation. Copyright (C) 2006 John Wiley & Sons, Ltd.

• Tip characterizer for atomic force microscopy

Hiroshi Itoh, Toshiyuki Fujimoto, Shingo Ichimura

REVIEW OF SCIENTIFIC INSTRUMENTS   77 ( 10 )  2006.10  [Refereed]

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A tip characterizer for atomic force microscopy (AFM) was developed based on the fabrication of multilayer thin films. Comb-shaped line and space (LS) and wedge-shaped knife-edge structures were fabricated on a GaAs substrate. GaAs/InGaP superlattices were used to control the width of the structures precisely, and selective chemical etching was used to form sharp edges on the nanostructures. The minimum size of the LS structure was designed to be 10 nm, and the radius of the knife edge was less than 5 nm. These nanostructures were used as a well-defined tip characterizer to measure the shape of a tip on a cantilever from line profiles of AFM images. (c) 2006 American Institute of Physics.

• Secondary ion mass spectrometry of organic thin films using metal-cluster-complex ion source

Yukio Fujiwara, Kouji Kondou, Hidehiko Nonaka, Naoaki Saito, Hiroshi Itoh, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   45 ( 33-36 ) L987 - L990  2006.09  [Refereed]

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Tetrairidium dodecacarbonyl, Ir-4(CO)(12), is a metal cluster complex that has a molecular weight of 1104.9. Using a metal-cluster-complex ion source, secondary ion mass spectrometry (SIMS) of poly(methyl methacrylate) (PMMA) thin films on silicon substrates was performed with a quadrupole mass spectrometer. The secondary ion intensity of PMMA bombarded with Ir-4(CO)(7)(+) ions was investigated in the beam energy ranging from 3 to 10keV at an incident angle of 45 degrees. For comparison, bombardment with oxygen ions, O-2(+), was also tested. It was confirmed that the use of Ir-4(CO)(7)(+) ions enhanced secondary ion intensity by at least one order of magnitude compared with that Of O-2(+) ions. Experimental results also showed that secondary ion intensity increased with beam energy; particularly, high-mass secondary ion intensity markedly increased.

• Ion-beam characteristics of the metal cluster complex of Ir-4(CO)(12)

Yukio Fujiwara, Kouji Kondou, Yoshikazu Teranishi, Hidehiko Nonaka, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura, Mitsuhiro Tomita

JOURNAL OF APPLIED PHYSICS   100 ( 4 )  2006.08  [Refereed]

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Tetrairidium dodecacarbonyl, Ir-4(CO)(12), is a metal cluster complex which has a molecular weight of 1104.9. Using a metal-cluster-complex ion source, it has been demonstrated that stable ion beams of Ir-4(CO)(7)(+) were produced. Energy dependence of sputtering yield of silicon bombarded with Ir-4(CO)(7)(+) ions was investigated at a beam energy from 2 to 10 keV at normal incidence. Experimental results showed that the sputtering yield varied substantially with beam energy. The sputtering yield at 10 keV was higher than that with SF5+ or Ar+ ions by a factor of 3-24, whereas the sputtering yield at 3 keV was lower than that with Ar+ ions. In the case of 2 keV, deposition was found to occur. The substantial variation in the sputtering yields was examined using empirical equations for calculating sputtering yields. It was shown that the high sputtering yield at 10 keV would be due to what is called "nonlinear effect" unique to complex-projectile bombardment. It was also indicated that the substantial variation in the sputtering yield would result from lower kinetic energies of each atom constituting the cluster ions. Further, the deposition was explained by considering changes in surface properties caused by the irradiation of the cluster ions. (c) 2006 American Institute of Physics.

• M. Tomita, T. Kinno, M. Koike, H. Tanaka, S. Takeno, Y. Fujiwara, K. Kondou, Y. Teranishi, H. Nonaka, T. Fujimoto, A. Kurokawa, S. Ichimura

APPLIED PHYSICS LETTERS   89 ( 5 )  2006.07

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Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir-4(CO)(7)(+) as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of similar to 1 nm under 5 keV, 45 degrees condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5 keV with higher incident angles.

• Production of stable ion beam of Os-3(CO)(12) with compact metal-cluster-complex ion source

Yukio Fujiwara, Kouji Kondou, Yoshikazu Teranishi, Hidehiko Nonaka, Toshiyuki Fujimoto, Akira Kurokawa, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 7 ) 6000 - 6007  2006.07  [Refereed]

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Metal-cluster-complex ion beams were produced stably using a cluster ion source, which is compact enough to be installed in commonly used secondary ion mass spectrometry (SIMS) systems: As a metal cluster complex, triosmium dodecacarbonyl, Os-3(CO)(12), was utilized, which has a molecular weight of 906.7. Since precise temperature control is necessary to sublimate,the metal cluster, complex stably without thermal decomposition, the ion source was equipped with compact heat-removal devices in addition to an external heater. Experimental results showed that the crucible temperature of the metal cluster complex can be maintained at about 130 degrees C in continuous operation, which is an appropriate temperature for sublimation without the problem of decomposition. The ion source produced steady-state beams Of Os-3(CO)(n')(+) (n = 7 or 8) ions with a beam current exceeding 10 nA at 10 keV. Beam current increased with gas pressure, depending on the temperature of the crucible holding the metal cluster complex. The rate of the change in beam current was within a few,percent per hour; hence, in view of stability, the ion source was confirmed. as usable in SIMS. Furthermore, beam profile was investigated using a Faraday cup with a knife-edge as well as a GaAs/AlAs multilayer substrate as a beam target.

• Observation of sputtered Si surface irradiated with metal cluster complex ions

Yoshikazu Teranishi, Kouji Kondou, Yukio Fujiwara, Hidehiko Nonaka, Misuhiro Tomita, Kazuhiro Yamamoto, Toshiyuki Fujimoto, Shingo Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 6B ) 5528 - 5530  2006.06  [Refereed]

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We report the results of surface sputtering of Si using a proto type ion source to utilize a compact cluster ion source which was developed using Os-3(CO)(12) as a low-damage sputtering source. The surface roughening of Si sputtered with cluster ions with an acceleration energy of 10 keV at incidence angles between 0 and 60 degrees was investigated. The sputtered Si surface was observed using an atomic force microscope and a scanning electron microscope. At incident angles between 0 and 45 degrees, the surface remained smooth while at 60 degrees, roughening was observed.

• M Ohkubo, Y Shigeri, T Kinumi, N Saito, M Ukibe, YE Chen, A Kushino, A Kurokawa, H Sato, S Ichimura

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   559 ( 2 ) 779 - 781  2006.04

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Fragmentation of precursor ions of peptides or proteins is very promising for sequencing with matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (TOF-MS). Neutral fragments Lis well Lis ions produced by post-source decay (PSD) were measured by a superconducting tunnel junction detector in a linear TOF-MS. It has been demonstrated that the PSD fragments are observable as event bands with different kinetic energies at the same TOF as that of the precursor ions of polystyrene with a nominal mass of 200 kDa and bovine serum albumin of 66.43 kDa. (c) 2006 Elsevier B.V. All rights reserved.

• A Suzuki, A Kurokawa, H Nonaka, S Ichimura

SENSORS AND ACTUATORS A-PHYSICAL   127 ( 1 ) 37 - 40  2006.02

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In this work, we present a novel method for hydrogen sensing, based on partial pressure measurements with a diaphragm and a quartz friction pressure gauge (D- and Q-gauges, respectively). The D-gauge measures absolute pressure, whereas Q-gauge readings are affected by viscosity changes occurring when hydrogen is mixed with air, thus enabling H-2 detection. The new method is safe and sensitive and has a quick-response to hydrogen leakage. The measured minimum detection limit for hydrogen is 0.05 vol.% in air, and the response time to hydrogen introduction is less than 1 s-, these characteristics are practically sufficient for hydrogen sensing. (c) 2005 Elsevier B.V. All rights reserved.

• ICHIMURA Shingo

Journal of the Japan Society for Abrasive Technology   50 ( 2 ) 65 - 68  2006.02

• AN Bai, WEN Mao, FUKUYAMA Seiji, YOKOGAWA Kiyoshi, ICHIMURA Shingo, YOSHIMURA Masamichi

Shinku   49 ( 1 ) 6 - 11  2006.01

• S Tanuma, T Shiratori, T Kimura, K Goto, S Ichimura, CJ Powell

SURFACE AND INTERFACE ANALYSIS   37 ( 11 ) 833 - 845  2005.11

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We have determined electron inelastic mean free paths (IMFPs) in C (graphite), Si, Cr, Fe, Cu, Zn, Ga, Mo, Ag, Ta, W, Pt and Au by elastic-peak electron spectroscopy (EPES) using Ni as a reference material for electron energies between 50 and 5000 eV. These IMFPs could be fitted by the simple Bethe equation for inelastic electron scattering in matter for energies from 100 to 5000 eV. The average root-mean-square (RMS) deviation in these fits was 9%. The IMFPs for Si, Cr, Fe, Cu, Ag, Ta, W, Pt and Au were in excellent agreement with the corresponding values calculated from optical data for energies between 100 and 5000 eV. While the RMS differences for graphite and Mo in these comparisons were large (27 and 17%, respectively), the average RMS difference for the other 11 elements was 11%. Similar comparisons were made between our IMFPs and values obtained from the TPP-2M predictive equation for energies between 100 and 5000 eV, and the average RMS difference for the 13 solids was 10.7%; in these comparisons, the RMS differences for Ta and W were relatively large (26% for each). A correction for surface-electronic excitations was calculated from a formula of Werner et al.; except for Si and Ga, the average correction was 5% for energies between 150 and 5000 eV. The satisfactory consistency between the IMFPs from our EPES experiments and the corresponding IMFPs computed from optical data indicates that the uncertainty of these IMFPs is about 11% for electron energies between 100 and 5000 eV. Similar comparisons with IMFPs from the EPES experiments of Werner et al. showed a consistency of 8% for energies between 200 and 5000 eV. Copyright (C) 2005 John Wiley & Sons, Ltd.

• Vibrational spectroscopic study of the interface of SiO2/Si(100) fabricated by highly concentrated ozone: Direct evidence for less strained Si-O-Si bond angle

K Nakamura, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 10 ) 7602 - 7604  2005.10  [Refereed]

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The interface structure Of SiO2/Si(100) synthesized with a highly concentrated ozone gas was analyzed by Fourier-transformed infrared absoption spectroscopy (FT-IR). The position of a transverse optical (TO) phonon peak of Si-O-Si asymmetric stretching vibration, which is a function of a Si-O-Si bond angle, remains constant at 1065 cm(-1) within a similar to 2 nm thickness of an ozone-oxide film. This result indicates that the thickness of structural transition layers at this interface where the Si-O-Si angle is distorted due to the stress at the interface is considerably limited, which is in contrast to a thermal oxide film on Si(100) showing the existence of structural transition layers.

• SATO Yosuke, NISHIGUCHI Tetsuya, NONAKA Hidehiko, ICHIMURA Shingo, NIHEI Yoshimasa

Shinku   48 ( 6 ) 378 - 381  2005.06

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A local and real-time concentration measuring method for high concentration ozone gas has been developed. The method employs Quadrupole Mass Spectroscopy (QMS) calibrated by low-temperature Thermal Desorption Spectroscopy (TDS). It was impossible to estimate the local ozone concentration by sampling the exhaust gas from the evacuation line. Using the passivated line, ozone concentration at a desired sampling point could be measured directly by the present method. The usefulness of the method was demonstrated by measuring ozone concentration at two particular points in oxidation chamber to be 23% and 40%.

• M Ohkubo, M Ukibe, N Saito, A Kushino, S Ichimura, S Friedrich

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   15 ( 2 ) 932 - 935  2005.06

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Spatial uniformity of superconducting tunnel junction detectors with a size of 200 mu m is improved by increasing Al thickness of the Nb/Al proximized electrodes in an energy range of 5-10 keV. which is in the same order as an acceleration energy in time-of-flight mass spectroscopy (TOF-MS). It has been confirmed in the TOF experiments with Ta ions and Th clusters that the proximized junction detectors clearly separate different ionic states and multi-hit events in impact energy spectra, and moreover can reveal the difference in ion species or ion-surface collision dynamics. However, a better spatial uniformity is not always good for TOF-MS, possibly because a detector with the thicker Al layers has a lower superconducting energy gap, which results in an improper detector operation because of a temperature rise.due to heat radiation, or the states of the detector surfaces are different.

• SIMS Depth Profiling of Characteristic Thin Surface Layers Formed in Titanium by Mechanical Abrasion and Annealing.

Shigeru Suzuki, Toshio Sato, Akira Kurokawa, Shingo Ichimura

Journal of Surface Analysis   12 ( 2 ) 166 - 169  2005.04  [Refereed]

• Synthesis of silicon dioxide film using high-concentration ozone and evaluation of the film quality

K Koike, K Izumi, S Nakamura, G Inoue, A Kurokawa, S Ichimura

JOURNAL OF ELECTRONIC MATERIALS   34 ( 3 ) 240 - 247  2005.03  [Refereed]

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We investigated the ozone oxidation characteristics on a hydrogen-terminated Si substrate. A high-concentration ozone gas generator with an ozone condensation unit was specially designed and assembled for this study. During the oxidation by ozone with the concentration of 25 vol.% in the temperature range from 340 degrees degrees C to 625 degrees C at 8 Torr (1.1 kPa), the formed oxide film thickness increased with oxidation time in accordance with the parabolic law, which suggests a diffusion-controlled step, while the oxidation by pure oxygen attained saturated states within 3 min of initiating oxidation. The activation energy for parabolic constants in the ozone oxidation was determined to be 0.52 ev This value is much smaller than the activation energy for dry oxidation with oxygen, while it is almost the same as that in the plasma oxidation with the mixture of rare gas and oxygen. Moreover, the quality of the ozone oxidation film was evaluated by estimating the amount of suboxides (Si3+ + Si2+ + Si+) using x-ray photoelectron spectroscopy (XPS) analysis and the compressive stress using Fourier transform infrared (FT-IR) spectroscopic analysis. Both results showed that the quality of film subjected to ozone oxidation at 500 degrees C is equal or superior to that of the film subjected to pyrogenic oxidation at 750 degrees C in spite of the faster oxidation rate, and thus, the significant advantages of ozone oxidation at low oxidation temperatures could be confirmed.

• T Fujimoto, T Mizota, H Nonaka, A Kurokawa, S Ichimura

SURFACE AND INTERFACE ANALYSIS   37 ( 2 ) 164 - 166  2005.02

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Metal cluster complexes, including the colloidal metal cluster, were applied to establish the low damage sputtering method. Electro-spray-like ionization using an ink-jet nozzle has the potential to produce a cluster ion beam. A colloidal Au cluster of size 5 nm made a large crater-like hole at the carbon sheet. Copyright (C) 2005 John Wiley Sons, Ltd.

• Rapid and uniform SiO2 film growth on 4 inch Si wafer using 100%-O-3 gas

T Nishiguchi, Y Sato, H Nonaka, S Ichimura, T Noyori, Y Morikawa, M Kekura, Y Nihei

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 1A ) 118 - 124  2005.01  [Refereed]

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We have developed a lamp-heated cold-wall chamber that can process a large Si wafer using a highly concentrated (&gt; 90 vol. %) ozone gas to achieve rapid and uniform oxidation at a lower temperature than that used in conventional thermal oxidation. Uniform SiO2 formation with a film thickness uniformity of within 0.2 nm was achieved. The SiO2 growth rate, however, was not markedly accelerated compared with that achieved using conventional low (i.e., 10 vol. %)-concentration O-3 gas. This was considered to originate from the decomposition of O-3 gas in the gas phase before arriving at a heated surface as determined from the local ozone concentration measurements we performed, By increasing gas flow velocity so as to reduce the area of the thermal boundary layer on the heated surface in which decomposition of O-3 to molecular oxygen is enhanced, SiO2 growth rate was actually improved.

• Low-temperature oxidation of silicon using UV-light-excited ozone

A Tosaka, T Nishiguchi, H Nonaka, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   44 ( 33-36 ) L1144 - L1146  2005  [Refereed]

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An ultra low-temperature (&lt; 300 degrees C) silicon oxidation process in which KrF excimer laser light (lambda = 248 nm) is irradiated in highly concentrated ozone has been developed. The growth rate Of SiO2 film was 5.2 nm/10 n-fin at 300 degrees C and 3.6 nm/10 min at 70 degrees C. The leakage current densities of grown at 70 degrees C SiO2 in an electric field of over 8 MV/cm match well the calculated curve based on the Fowler-Nordheim tunneling. The oxidation mechanisms for two growth modes are discussed.

• Development of a continuous generation/supply system of highly concentrated ozone gas for low-temperature oxidation process

S Ichimura, H Nonaka, Y Morikawa, T Noyori, T Nishiguchi, M Kekura

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A   22 ( 4 ) 1410 - 1414  2004.07  [Refereed]

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A system is described which can continuously generate/supply highly concentrated (HC) ozone gas to satisfy the future need for practical low-temperature oxidation. This system comprises four ozone vessels, each with independent temperature control. The system can supply a constant flow of HC ozone gas by allocating one of four modes of operation, i.e., accumulation/storage, vaporization (supply), evacuation, and cooling, to each of the ozone vessels so that all the modes can be simultaneously addressed. The maximum flow rate is 60 sccm with a flux stability of +/-1.1%, and an ozone concentration of over 99.5 vol% can be achieved at the system outlet. The system was applied to the formation of an ultrathin SiO2 film on a 4 in. diameter silicon wafer substrate. (C) 2004 American Vacuum Society.

• T Mizota, H Nonaka, T Fujimoto, A Kurokawa, S Ichimura

APPLIED SURFACE SCIENCE   231   945 - 948  2004.06

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In order to develop a new compact cluster ion source as a low damage sputtering source for SIMS to analyze ultra-shallow dopant state we have studied the possibility of using a metal cluster complex as an ion beam source. Metal cluster complexes such as Os-3(CO)(12) and Ir-4(CO)(12) have been studied from the view point of their stability in high vacuum and how to ionize them by using the electron ionization QMS and the XeCl laser ionization TOE In the case of electron ionization QMS, peaks of Os-3(CO)(n)(+)(n = 0-12) and lr(4)(CO)(n)(+) (n = 0-12) were observed without the fragment ions such as a monomer, a dimer, etc. In the case of laser ionization TOF, peaks of the fragment and the parent ions without a carbonyl ligand were observed from Os-3(CO)(12), and Ir-4(CO)(12). The temperature dependence of fragmentation has also been discussed. (C) 2004 Elsevier B.V. All rights reserved.

• 一村信吾

化学と工業   57 ( 4 ) 423 - 426  2004.04

• M Ohkubo, M Ukibe, T Zama, T Ikeuchi, M Katagiri, S Ichimura

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 231 - 233  2004.03

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It has been demonstrated by Low-Temperature Scanning Synchrotron Microscope that the spatial profiles of Nb/Al/AlOx/Al/Nb detectors are abnormally large in an energy range between 2 and 10 keV, and thus the detectors produce no clear total absorption peaks. Below 2 keV, on the other hand, full illumination experiments have afforded the evidence that the spatial uniformity is significantly improved, for example, an 100 gm square junction has an intrinsic energy resolution of 5.4 eV at 200 eV. These results reconfirm that carefully designed junction detectors with a reasonable size are ideal for energy-dispersive spectroscopy in a soft X-ray range. (C) 2003 Elsevier B.V. All rights reserved.

• Partial-pressure measurement of atmospheric-pressure binary gas using two pressure gauges

A Kurokawa, K Odaka, S Ichimura

VACUUM   73 ( 2 ) 301 - 304  2004.03  [Refereed]

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We investigated a new method to measure the partial pressure of a binary gas system at near-atmospheric pressure conditions. The method utilizes two types of vacuum gauges, a capacitance manometer and a quartz friction pressure gauge. The partial pressure of the binary gas can be estimated by measuring the impedance change with a quartz friction pressure gauge, which depends on both viscosity and total pressure of a binary gas, and considering the total pressure change as measured by a capacitance manometer. We applied this method to measure the partial pressure of ozone in an ozone-oxygen gas mixture. The results suggested that the new method allows a partial-pressure measurement of ozone with an accuracy of Deltap = 0.2 kPa, close to atmospheric pressure. The advantages of the new method include compact size, high safety standards when measuring highly reactive gases, and the allowance for in-line monitoring. (C) 2003 Elsevier Ltd. All rights reserved.

• Relationship between ozone oxidation and stress evolution on an H-terminated Si surface

A Kurokawa, T Narushima, K Nakamura, H Nonaka, S Ichimura, AN Itakura, M Kitajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 1 ) 281 - 286  2004.01  [Refereed]

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We observed the stress evolution of an H-terminated Si (100) surface during ozone oxidation and the ozone oxidation on a partially H-terminated Si surface of Si (100) and Si (111) to study the surface orientation effect on ozone oxidation. The evolution of stress on the H-terminated Si (100) surface was observed in real-time by an optical micro-mechanical cantilever method. The results show that the stress evolution on the H-terminated Si surface was unexpectedly large when considering that H-termination reduced the sticking amount of oxygen. Both the Si (111) and Si (100) surfaces showed that the rate of ozone oxidation was reduced as hydrogen covered the surfaces. However, at high-H coverage the H-terminated Si (111) surface showed a greater increase of sticking rate than the H-terminated Si (100) surface. The relationship between the oxidation-induced stress and oxidation rate is discussed.

• ICHIMURA Shingo

Hyomen Kagaku   24 ( 4 ) 207 - 214  2003

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Charging phenomena that occur during XPS and AES analysis of insulating materials are discussed, with special focus on surface potential change by X-ray or electron beam irradiation. Some typical examples of charging phenomena observed during XPS analysis are introduced together with practical methods for charge compensation and for the estimation of peak shifts by charging. As the practical methods are now under discussion in the frame of ISO activities, the content of relating ISO document (ISO 19318) is also briefly explained. Then charging phenomena observed in AES analysis of insulating materials are discussed in terms of the relation between surface charging and secondary electron emission, for which a new concept of static/dynamic secondary electron yield is explained. Practical methods for charge compensation in AES analysis are also introduced, and experimental results showing the effect of those methods are presented.

• ICHIMURA SHINGO

触媒   44 ( 7 ) 571 - 576  2002.10

• High-quality SiO2 film formation by highly concentrated ozone gas at below 600 degrees C

T Nishiguchi, H Nonaka, S Ichimura, Y Morikawa, M Kekura, M Miyamoto

APPLIED PHYSICS LETTERS   81 ( 12 ) 2190 - 2192  2002.09  [Refereed]

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Highly concentrated (&gt;93 vol %) ozone (O-3) gas was used to oxidize silicon for obtaining high-quality SiO2 film at low temperature. Compared to O-2 oxidation, more than 500 degreesC lower temperature oxidation (i.e., from 830 to 330 degreesC) has been enabled for achieving the same SiO2 growth rate. A 6 nm SiO2 film, for example, could be grown at 600 degreesC within 3 min at 900 Pa O-3 atmosphere. The temperature dependence of the oxidation rate is relatively low, giving an activation energy for the parabolic rate constant of 0.32 eV. Furthermore, a 400 degreesC grown SiO2 film was found to have satisfactory electrical properties with a small interface trap density (5x10(10) cm(-2)/eV) and large breakdown field (14 MV/cm). (C) 2002 American Institute of Physics.

• Effect of highly concentrated ozone on the etching properties of preoxide films on Si(100)

K Nakamura, S Ichimura, A Kurokawa, K Koike

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   41 ( 7A ) L754 - L757  2002.07  [Refereed]

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We have investigated the effect of ozone on already existing silicon oxide films as preoxide on Si(100). The use of highly concentrated ozone (25 vol%) at atmospheric pressure has made it possible to modify a native oxide film on Si(100) at 350degreesC, resulting in upgraded film quality and reduced thickness of structural transition layers. This was shown by the change of an etching rate by hydrofluoric acid (HF) solution of the oxide film exposed to ozone. However, the exposure of ozone to Si(100) at 350degreesC with an already existing thermally grown oxide film caused no change in the distribution of transition layers in the oxide. This contrast suggests the possibility of upgrading the properties of a preoxide film without structural transition layers at the appropriate substrate temperature.

• Enhanced silicon oxidation by a hyperthermal beam obtained from laser evaporation of solid ozone

T Nishiguchi, Y Morikawa, M Kekura, M Miyamoto, H Nonaka, S Ichimura

JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 5 ) F29 - F34  2002.05  [Refereed]

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A new oxidation method for gate oxide applications using a collimated neutral hyperthermal ozone beam produced by pulsed laser evaporation of solidified ozone is demonstrated. This method enables ozone molecules, together with oxygen molecules and oxygen atoms, in an electronically excited state, O(D-1), with a translational energy of around 1 eV to be intermittently supplied to silicon just after each laser shot, so that the silicon dioxide (SiO2) film thickness can be accurately controlled by the number of laser shots. The effect of ozone having this translational energy was clearly apparent from the temperature-independent initially high oxidation rate, which enabled the oxidation to be shorter and with a lower temperature process. Compared to oxidation by the conventional method using thermal ozone gas, higher efficiency was achieved in the sense that a thicker SiO2 film could be obtained with a smaller number of ozone molecules as long as the oxidized area was localized. Further enhanced oxidation was enabled by using a hyperthermal beam rich in O(D-1) that had been obtained at a high laser fluence irradiation, demonstrating the high reactivity of O(D-1) compared to the ground-state oxygen atom, O(P-3). (C) 2002 The Electrochemical Society.

• Reactive oxygen beam generation system using pulsed laser evaporation of highly concentrated solid ozone

T Nishiguchi, Y Morikawa, M Kekura, M Miyamoto, H Nonaka, S Ichimura

REVIEW OF SCIENTIFIC INSTRUMENTS   73 ( 3 ) 1217 - 1223  2002.03  [Refereed]

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A reactive oxygen beam generation system is described for the formation of high-quality and high-precision films. This system utilizes pulsed laser evaporation of highly concentrated solidified ozone (O-3). The equipment for safely generating and handling a large amount of high-purity liquid and solid O-3 was also developed for this purpose. The beam is characterized by its high concentration of oxygen atoms in an excited state [O(D-1)], constant flux per laser shot (4x10(17) molecules cm(-2) shot(-1)), appropriate level of kinetic energy (KE) for enhancing the surface reaction (mean KE of 0.4 eV, maximum KE of 2 eV) and small angular spread (6degrees). These characteristics enabled us to precisely control the SiO2 film thickness by the number of laser shots, and achieve an enhanced Si oxidation rate and new local oxidation process. (C) 2002 American Institute of Physics.

• Highly concentrated ozone gas supplied at an atmospheric pressure condition as a new oxidizing reagent for the formation of SiO2 thin film on Si

K Koike, S Ichimura, A Kurokawa, K Nakamura

JOURNAL OF ELECTRONIC MATERIALS   31 ( 2 ) 108 - 112  2002.02  [Refereed]

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We have investigated the characteristics of silicon oxidation by concentrated ozone gas through the comparison of the oxidation by oxygen molecules. A sophisticated high-concentration ozone generator, which exploits the ozone/oxygen gas separation technique with silica gel, has been developed for the study. The generator can continuously supply ozone-oxygen mixtures with ozone concentrations up to 30 at.% at one atmospheric pressure. Ozone gas with a concentration of 25 at.% from the generator formed SiO2 films as thick as 2 nm and 6 nm on Si for a 30 min. exposure at 200degreesC and 600degreesC, respectively. On the other hand, oxygen gas by itself could form SiO2 films with only 1 nm and 3 nm thickness, respectively, at the same conditions. Moreover, in the oxide film formation at 600degreesC, the oxide film growth by ozone was proceeded with an oxidation time in excess of 240 min., while it saturated within very short time in the oxidation by oxygen. These phenomena verify the strong oxidation power of ozone. In addition, we confirmed that the growth rate of the silicon oxide with ozone dramatically changed when the substrate temperature was over 500degreesC, and this suggested the change of oxidation mechanism at this point. However, such a characteristic was not found in oxidation with oxygen.

• Nonaka H., Shimizu T., Arai K., Kurokawa A., Ichimura S.

Journal of Surface Analysis   9 ( 3 ) 344 - 347  2002

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The relative work function of growing surface of molecular epitaxy films was measured in situ using the energy shifts observed in secondary electrons excited by reflection high energy electron diffraction beam. In the case of a superconducting perovskite YBa2Cu3Ox the measured work function showed different behaviors between the coevaporation and the sequential evaporation of the metal elements reflecting differences in the electronic structures of the growing surfaces.

• T Nishiguchi, Y Morikawa, M Miyamoto, H Nonaka, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   40 ( 8B ) L897 - L899  2001.08

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We have performed KrF pulsed-laser evaporation of a cryogenic film consisting of a mixture of ozone (O-3) and nitrous oxide (N2O) to obtain an energetically reactive beam for oxidation as well as nitrogen (N) incorporation. The ejection of hyperthermal nitric oxide (NO) molecules as well as hyperthermal oxygen (O) atoms and N2O molecules was observed at a relatively high laser fluence. The generation of additional NO molecules is explained by the chemical reaction between O atoms in the electronically excited state, which are generated from photodissociation of O-3, and surrounding N2O molecules during the evaporation process. By applying this beam to Si, we have achieved an extremely high oxidation rate and 4-7 at.% N incorporation even at room temperature.

• Hyperthermal beam for oxidation and nitridation produced by laser evaporation of mixed O-3/N2O cryogenic film

T Nishiguchi, Y Morikawa, M Miyamoto, H Nonaka, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   40 ( 8B ) L897 - L899  2001.08  [Refereed]

View Summary

We have performed KrF pulsed-laser evaporation of a cryogenic film consisting of a mixture of ozone (O-3) and nitrous oxide (N2O) to obtain an energetically reactive beam for oxidation as well as nitrogen (N) incorporation. The ejection of hyperthermal nitric oxide (NO) molecules as well as hyperthermal oxygen (O) atoms and N2O molecules was observed at a relatively high laser fluence. The generation of additional NO molecules is explained by the chemical reaction between O atoms in the electronically excited state, which are generated from photodissociation of O-3, and surrounding N2O molecules during the evaporation process. By applying this beam to Si, we have achieved an extremely high oxidation rate and 4-7 at.% N incorporation even at room temperature.

• Enhanced oxidation of silicon using a collimated hyperthermal ozone beam

T Nishiguchi, Y Morikawa, M Miyamoto, H Nonaka, S Ichimura

APPLIED PHYSICS LETTERS   79 ( 3 ) 382 - 384  2001.07  [Refereed]

View Summary

Silicon was oxidized by a collimated hyperthermal ozone beam produced by pulsed-laser ablation of solid ozone to increase the controllability of the silicon dioxide film thickness and to achieve low-temperature oxidation. The oxidation rate could be accurately controlled by the number of laser shots to which the number of supplied ozone molecules was proportional. Ozone molecules with a translational energy of around 1 eV obtained by laser ablation produced an initially rapid oxidized region with no temperature dependence in which a 0.6 nm silicon dioxide film could be synthesized at room temperature with only 200 laser shots. Higher-efficiency oxidation was also achieved in comparison with that by using a spray of ozone with thermal energy. (C) 2001 American Institute of Physics.

• Nitrogen profile in SiOxNy prepared by thermal nitridation of ozone oxide

K Nakajima, K Kimura, A Kurokawa, S Ichimura, H Fukuda

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   40 ( 6A ) 4011 - 4012  2001.06  [Refereed]

View Summary

Ultrathin silicon oxynitride films are prepared by ozone and thermal oxidation of Si(001) followed by rapid thermal nitridation. The nitrogen depth profiles in these films are measured by high-resolution Rutherford backscattering spectroscopy. The observed nitrogen profiles are essentially similar, having a peak at the SiO2/Si interface, although the interface strain in the ozone oxide is known to be much smaller than that of the thermal oxide. This indicates that the interface strain relaxation due to the nitrogen incorporation is not responsible for the nitrogen accumulation at the interface.

• Initial oxidation process by ozone on Si(100) investigated by scanning tunneling microscopy

H Itoh, K Nakamura, A Kurokawa, S Ichimura

SURFACE SCIENCE   482   114 - 120  2001.06  [Refereed]

View Summary

Ozone is a strong oxidant due to its release of atomic oxygen. The initial ozone oxidation process at room temperature and the roughness of the interface were investigated using scanning tunneling microscopy (STM). The most favorable adsorption site was the bridge site on the Si dimer at initial oxidation using ozone gas. Less than 10% of the oxygen atoms on the surface were located at the bridge site between the Si dimers. The rest of the oxygen atoms were inserted into the backbond below the Si dimer atom near the defects. This indicates that the oxygen atom is inserted into the backbond of the Si dimer through original and etched defects. The interface of SiO2/Si was characterized after the oxide film was removed by hydrofluoric acid. STM images were obtained from the etched surface. The roughness of the STM image was below 0.2 nm rms. This result indicates that the interface between the silicon and ozone oxides limits the roughness to two to three SiO2 layers at most after oxidation by ozone. (C) 2001 Elsevier Science B.V. All rights reserved.

• Atomic force microscopy observation of layer-by-layer growth of ultrathin silicon dioxide by ozone gas at room temperature

T Maeda, A Kurokawa, K Sakamoto, A Ando, H Itoh, S Ichimura

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B   19 ( 2 ) 589 - 592  2001.03  [Refereed]

View Summary

Atomic structures on active oxidized silicon films by an ozone gas at room temperature are investigated by an atomic force microscopy. A step-terrace structure similar to that on a clean Si (001) prepared by a silicon homoepitaxy is preserved on the ozone oxidized surface. These atomically regulated structures are also discernible on the SiO2/Si interface when a 1.0-nm-thick SiO2 film oxidized by an atmospheric ozone is removed by a diluted HF etching. It is revealed that the homogeneous lateral oxide growth, i,e., layer-by-layer growth, proceeds at room temperature by an active oxidant such as ozone. (C) 2001 American Vacuum Society.

• Backscattering correction for AES spectra measured at oblique (&gt; 45 degrees) incidence of primary electron beam

Y Shimotsuma, S Ichimura

SURFACE AND INTERFACE ANALYSIS   31 ( 2 ) 102 - 105  2001.02  [Refereed]

View Summary

The validity of matrix corrections on an AES analysis for incident angles theta (measured from the surface normal) of &gt;45 degrees was examined. The correction factors to take into account were the atomic density correction factor (N), the electron backscattering correction factor (R) and the inelastic mean free path (lambda). The backscattering correction factor at large incidence angles was estimated by extrapolation from the factors for theta &lt; 45&lt;degrees&gt;, which have been reported based on Monte-Carlo simulations. The validity of the extrapolation was checked using pure Au and Cu samples used in the measurements of AES intensity dependence on the angle of incidence. This present approach then was applied to the quantitative analysis of Si3N4 samples for a large incident angles. It was confirmed that the proposed matrix correction method is more accurate than the conventional one based on the use of sensitivity factors. Copyright (C) 2001 John Wiley & Sons, Ltd.

• Ultrathin SiO2 film growth on Si by highly concentrated ozone

S Ichimura, A Kurokawa, K Nakamura, H Itoh, H Nonaka, K Koike

THIN SOLID FILMS   377   518 - 524  2000.12  [Refereed]

View Summary

The growth mechanism of SiO2 thin film on Si(100) and Si(111) by ozone was investigated using various surface/interface analytical techniques such as X-ray photoelectron spectroscopy (XPS), second harmonic generation (SHG) and medium energy ion scattering spectroscopy (MEIS). Two different ozone generators were fabricated and used for the investigation. The first ozone generator, which was used for the study of initial oxidation, supplies low pressure (&lt; 10(-2) Pa) and high purity (&gt; 80%) ozone gas by vaporization of pure liquid ozone at low temperature (&lt; 100 K). The second ozone generator, used mainly for ultrathin SiO2 film growth, supplies high pressure (1 atm) ozone gas with concentration &lt; 30% by desorbing ozone adsorbed on silica-gel. Through the comparison of ozone oxidation to the oxidation with molecular oxygen, followings features of the ozone oxidation were made clear. (i) Atomic oxygen dissociated from ozone molecules at Si surface directly attacks the back bond of Si, hence it can oxidize hydrogen-terminated Si which oxygen molecules cannot. (ii) The oxide thin film growth proceeds in layer-by-layer manner, especially at the initial stage of oxidation. (iii) Formation of suboxids at and/or near the SiO2/Si interface was suppressed, leading to a stable Si-O-Si network formation even at low pressure and low temperature condition. In addition to these features, the existence of no (or very thin) structural transition layer was suggested for ozone oxide film from MEIS experiments and etching experiment with dilute HF solution, while those experiments for thermally grown oxide showed the existence of the transition layers with thickness of approximately 1 nm. (C) 2000 Elsevier Science B.V. All rights reserved.

• T Nishiguchi, Y Morikawa, M Miyamoto, H Nonaka, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   39 ( 11B ) L1200 - L1202  2000.11

View Summary

In order to obtain a highly concentrated hyperthermal ozone beam for mow effective Si oxidation, we performed laser ablation of solid-ozone. A KrF pulse laser was irradiated onto solidified ozone on a sapphire substrate cooled to 30 to 60 K using a cryocooler. A mixture of ozone, molecular oxygen and atomic oxygen was detected using a time-of-flight method through a quadrupole mass filter. The velocity distribution of ablated ozone molecules was almost the same as the distribution at thermal equilibrium. An ozone beam with a fitted temperature of 2500 K and maximum transnational, energy of 3 eV was obtained under optimum laser conditions.

• Hyperthermal O-3 beam produced by laser ablation of solid-ozone film

T Nishiguchi, Y Morikawa, M Miyamoto, H Nonaka, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   39 ( 11B ) L1200 - L1202  2000.11  [Refereed]

View Summary

In order to obtain a highly concentrated hyperthermal ozone beam for mow effective Si oxidation, we performed laser ablation of solid-ozone. A KrF pulse laser was irradiated onto solidified ozone on a sapphire substrate cooled to 30 to 60 K using a cryocooler. A mixture of ozone, molecular oxygen and atomic oxygen was detected using a time-of-flight method through a quadrupole mass filter. The velocity distribution of ablated ozone molecules was almost the same as the distribution at thermal equilibrium. An ozone beam with a fitted temperature of 2500 K and maximum transnational, energy of 3 eV was obtained under optimum laser conditions.

• High-concentration ozone generator for oxidation of silicon operating at atmospheric pressure

K Koike, T Fukuda, S Ichimura, A Kurokawa

REVIEW OF SCIENTIFIC INSTRUMENTS   71 ( 11 ) 4182 - 4187  2000.11  [Refereed]

View Summary

A high-concentration ozone generator operating at atmospheric pressure was developed to produce ozone for use in fabrication of ultrathin silicon oxide films. A technique for adsorption onto silica gel, in which ozone has adsorption priority over oxygen, was adopted to obtain concentrated ozone. An ozone-oxygen mixture gas generated by a commercial ozonizer is fed in turn to three parallel adsorption columns that are kept at -60 degreesC. After the adsorption process, the ozone-enriched gas is desorbed by a slow warming of the columns from -60 to 0 degreesC and is stored in a storage vessel. Finally, the condensed ozone, at concentrations up to 30 vol % can be supplied continuously to a silicon oxidation chamber at atmospheric pressure and a constant flow rate. Moreover, highly concentrated ozone above 70 vol % can be produced in a batch process by using an additional purification procedure prior to the desorption. We confirmed that even with 25 vol % ozone gas, SiO2 film as thick as 6.3 nm grew on a Si substrate at 600 degreesC and 15 Torr in a 30 min exposure, while under the same experimental conditions only a 3.1 nm thick SiO2 film could be formed on the same substrate with pure oxygen. (C) 2000 American Institute of Physics. [S0034-6748(00)04710-9].

• S Tanuma, S Ichimura, K Goto

SURFACE AND INTERFACE ANALYSIS   30 ( 1 ) 212 - 216  2000.08

View Summary

We have determined the surface plasmon excitation correction (SEC) factor for nickel in the 200-5000 eV range from the ratios of the absolute elastic scattering electron intensities measured by a novel cylindrical mirror analyser and those by the Monte Carlo method. The inelastic mean free paths (IMFPs) of nickel used for the Monte Carlo method in the energy range specified were calculated by the Penn algorithm. The resulting SECs were smaller than the values calculated from Chen and Oswald general equations of surface excitation parameters (SEPs), which describe the influence of surface plasmon excitations by electrons crossing a solid surface. We also found that SEPs (obtained from SECs) could be fitted to the equation P-s(alpha, E) = C/[E-n cos(alpha) + C] or P-s(alpha, E) = aE(-b)/cos(alpha) (&lt;7% root-mean-square error) in the 200-5000 eV energy range, where P-s is the SEP, alpha is the surface crossing angle of the electron to the surface normal, n(= 0.41), C(= 5.39), a(= 1.7) and b(= 0.29) are parameters and E is the electron energy. Copyright (C) 2000 John Wiley & Sons, Ltd.

• S Ichimura, K Koike, A Kurokawa, K Nakamura, H Itoh

SURFACE AND INTERFACE ANALYSIS   30 ( 1 ) 497 - 501  2000.08

View Summary

We investigated the initial oxidation of Si(100) with ozone by comparison with oxidation by oxygen molecules using a specially fabricated ozone generator that could supply concentrated (typically 30 at.%) ozone gas at 1 atm pressure. We measured the thickness of the SiO2 film on the Si by XPS, using a thermal oxide film with a known thickness as a reference. We observed the growth of an SiO2 film on Si by ozone even at a sample temperature of 200 degrees C, verifying the strong oxidation power of ozone. The SiO2 film was similar to 2.3 nm thick for 100 min of exposure. The kinetics of oxidation with ozone showed a power law dependence relative to exposure time, with almost the same power value for the ozone gas at 1 atm as at 2000 Pa. However, the growth of the SiO2 film was saturated at the level of one monolayer when the ozone gas was supplied at 10(-4) Pa, which suggests to us a rapid decrease of the sticking (or reaction) probability of ozone on monolayer SiO2, Copyright (C) 2000 John Wiley & Sons, Ltd.

• XPS analysis of ultrathin SiO2 film growth on Si by ozone

S Ichimura, K Koike, A Kurokawa, K Nakamura, H Itoh

SURFACE AND INTERFACE ANALYSIS   30 ( 1 ) 497 - 501  2000.08  [Refereed]

View Summary

We investigated the initial oxidation of Si(100) with ozone by comparison with oxidation by oxygen molecules using a specially fabricated ozone generator that could supply concentrated (typically 30 at.%) ozone gas at 1 atm pressure. We measured the thickness of the SiO2 film on the Si by XPS, using a thermal oxide film with a known thickness as a reference. We observed the growth of an SiO2 film on Si by ozone even at a sample temperature of 200 degrees C, verifying the strong oxidation power of ozone. The SiO2 film was similar to 2.3 nm thick for 100 min of exposure. The kinetics of oxidation with ozone showed a power law dependence relative to exposure time, with almost the same power value for the ozone gas at 1 atm as at 2000 Pa. However, the growth of the SiO2 film was saturated at the level of one monolayer when the ozone gas was supplied at 10(-4) Pa, which suggests to us a rapid decrease of the sticking (or reaction) probability of ozone on monolayer SiO2, Copyright (C) 2000 John Wiley & Sons, Ltd.

• 下間靖彦, 一村信吾

J Surf Anal   7 ( 2 ) 196 - 202  2000.06

• Effects of ozone treatment of 4H-SiC(0001) surface

R Kosugi, S Ichimura, A Kurokawa, K Koike, K Fukuda, S Suzuki, H Okushi, S Yoshida, K Arai

APPLIED SURFACE SCIENCE   159   550 - 555  2000.06  [Refereed]

View Summary

The effects of high-concentration ozone gas (similar to 25%) exposure at atmospheric pressure with and without ultraviolet (UV) irradiation to a 4H-SiC(0001) surface has been investigated by X-ray photoelectron spectroscopy (XPS). The C 1s XPS spectrum for the 4H-SiC surface after standard RCA cleaning showed the appearance of a chemically shifted peak on the higher binding energy side of the SiC bulk peak. The chemically shifted peak was also observed even for the surface prepared by dipping a sample with sacrificed oxide film into 5% HF solution. Curve-fitting analysis using the Gaussian function revealed that the chemically shifted peak consisted of three components. The chemically shifted peak could be sufficiently eliminated using ozone exposure with UV irradiation. The cleaning mechanism of the 4H-SiC surface by ozone exposure is discussed, referring to the analysis of peak intensity for each component under different surface conditions corresponding to RCA cleaning and ozone exposure with and without W irradiation. (C) 2000 Published by Elsevier Science B.V.

• Initial Oxidation of Si(100)$2{\times}1$ by Ozone: Transition of Growth Kinetics from Adsorption to Ultrathin Film Growth

Nakamura Ken, Kurokawa Akira, Ichimura Shingo

Jpn J Appl Phys   39 ( 4 ) L357 - L359  2000.04

View Summary

We have investigated the initial oxide growth kinetics on Si(100)$2{\times}1$ by highly concentrated ozone (${&gt;}80$%) using X-ray photoelectron spectroscopy. Initial oxidation of ${&lt;}0.6$ nm was found to proceed in accordance with Langmuir kinetics. However, a growth mode changed into linear kinetics at the oxide thickness of 0.6 nm on the surface at ${&gt;}550{\degC}$, while no further growth of oxide films ${&gt;}0.6$ nm was observed on the surface at ${&lt;}500{\degC}$ under the same pressure condition. This clear transition of kinetics has contributed to the successful growth of an oxide film ${&gt;}0.6$ nm which is difficult to synthesize using molecular oxygen under the same processing conditions.

• Initial oxidation of Si(100)2 x 1 by ozone: Transition of growth kinetics from adsorption to ultrathin film growth

K Nakamura, A Kurokawa, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   39 ( 4B ) L357 - L359  2000.04

View Summary

We have investigated the initial oxide growth kinetics on Si(100)2x1 by highly concentrated ozone (&gt;80%) using X-ray photoelectron spectroscopy. Initial oxidation of &lt;0.6 nm was found to proceed in accordance with Langmuir kinetics. However, a growth mode changed into linear kinetics at the oxide thickness of 0.6 nm on the surface at &gt;550 degrees C, while no further growth of oxide films &gt;0.6 nm was observed on the surface at &lt;500 degrees C under the same pressure condition. This clear transition of kinetics has contributed to the successful growth of an oxide film &gt;0.6 nm which is difficult to synthesize using molecular oxygen under the same processing conditions.

• Initial oxidation of Si(100)2 x 1 by ozone: Transition of growth kinetics from adsorption to ultrathin film growth

K Nakamura, A Kurokawa, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   39 ( 4B ) L357 - L359  2000.04  [Refereed]

View Summary

We have investigated the initial oxide growth kinetics on Si(100)2x1 by highly concentrated ozone (&gt;80%) using X-ray photoelectron spectroscopy. Initial oxidation of &lt;0.6 nm was found to proceed in accordance with Langmuir kinetics. However, a growth mode changed into linear kinetics at the oxide thickness of 0.6 nm on the surface at &gt;550 degrees C, while no further growth of oxide films &gt;0.6 nm was observed on the surface at &lt;500 degrees C under the same pressure condition. This clear transition of kinetics has contributed to the successful growth of an oxide film &gt;0.6 nm which is difficult to synthesize using molecular oxygen under the same processing conditions.

• ICHIMURA Shingo

Journal of High Pressure Institute of Japan   38 ( 2 ) 73 - 84  2000

View Summary

Curent technologies to establish UHV and XHV conditions and present methods to measure UHV/XHV conditions were summarized and discussed. From the view point of UHV/XHV genetarion, the importance of controlling outgassing from vacuum chambers was first explained based on the equation of evacuation. Then several methods effective to reduce the outgassing rate were introduced. Those methods are application of electrochemical polishing, vacuum pre-baking, BN and TiN coating on SUS, and also the adoption of other materials than SUS such as aluminum and copper. The outgassing from pumping system and also the reduction of it were also discussed. As to UHV/XHV measurement, several principal problems associated with XHV measurement were first discussed, which were followed by the introduction of new XHV gauges and new measurement methods developed to overcome those problems.

• Reduction of the interfacial Si displacement of ultrathin SiO2 on Si(100) formed by atmospheric-pressure ozone

A Kurokawa, K Nakamura, S Ichimura, DW Moon

APPLIED PHYSICS LETTERS   76 ( 4 ) 493 - 495  2000.01  [Refereed]

View Summary

We examined the structure around the interface of SiO2 and Si using medium-energy ion scattering spectroscopy (MEIS) to investigate the interfacial Si displacement of an ultrathin silicon dioxide formed by oxidation of a Si(100) substrate with atmospheric-pressure ozone at a substrate temperature of 375 degrees C. A thermally grown oxide with the same thickness as an ozone-formed oxide was also measured with MEIS for comparison. The ozone-formed oxide exhibited considerably less Si displacement in the oxide layers near the interface than a thermally grown oxide, which indicates that an ozone oxide is homogenous. These results explain well our previous findings that an ozone oxide exhibits a constant HF etching rate of silicon dioxide while a thermally grown oxide slows the etching rate near the interface. (C) 2000 American Institute of Physics. [S0003-6951(00)03704-9].

• Ultrathin silicon oxide film on Si(100) fabricated by highly concentrated ozone at atmospheric pressure

K Nakamura, S Ichimura, A Kurokawa, K Koike, G Inoue, T Fukuda

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A   17 ( 4 ) 1275 - 1279  1999.07  [Refereed]

View Summary

We have investigated ultrathin silicon oxide film growth by highly concentrated ozone at atmospheric pressure. Oxide film &gt;2 nm was grown on as-received Si(100) even at room temperature. The etching rate by dilute hydrofluoric acid solution of oxide fabricated on Si(100) at 350 degrees C by this method was almost the same as that of thermally grown oxide so that him density is equivalent to that of thermally grown oxide. The etching rate of this film also shows no dependence on the film depth. This is indicating that the transition layer due to the lattice mismatch of substrate and oxide is limited within a thinner region than that of thermally grown oxide. It also indicates that an oxide film with higher film density can be synthesized on the surface with preoxide film already formed to protect bare substrate surfaces. (C) 1999 American Vacuum Society. [S0734-2101(99)17204-X].

• 一村信吾

化学工学   63 ( 5 ) 264 - 268  1999.05

• Hydrofluoric acid etching of ultra thin silicon oxide film fabricated by high purity ozone

K Nakamura, A Kurokawa, S Ichimura

THIN SOLID FILMS   343   361 - 364  1999.04  [Refereed]

View Summary

Hydrofluoric acid etching indicates that ultra thin silicon dioxide film made by high purity ozone on Si(100)2 x 1 between 300 and 700 degrees C has the same film density as that of thermally grown silicon dioxide for device use on Si(100) at 750 degrees C in a wet environment. Rate of oxide film growth &gt; 6 Angstrom on Si(100)2 x 1 by ozone is, however, much lower at the substrate temperature between 300 and 500 degrees C than at 700 degrees C. This is indicating different kinetics and mechanism of oxide film growth &gt; 6 Angstrom by high purity ozone. (C) 1999 Elsevier Science S.A. All rights reserved.

• Shingo Ichimura, Kiyohide Kokubun, Masahiro Hirata, Sonoko Tsukahara, Kzuya Saito, Yoshinao Ikeda

Vacuum   53 ( 1-2 ) 291 - 294  1999

View Summary

The construction of a new vacuum system fabricated for pressure calibration in UHV/XHV region is explained together with the measurement of outgassing rate from an XHV chamber used in the system. The outgassing rate was measured using a test chamber by a throughput method after each treatment of the chamber surface such as electrolytic polishing, pre-baking in vacuum, and TiN coating. It was found that the outgassing rate of 3.7 × 10-9 Pa m s-1 after electrolytical polishing could be reduced to 1.0 × 10-13 Pa m s-1 after pre-baking twice followed by TiN coating. The outgassing rate was also measured by the pressure rise method using the whole XHV chamber, and the result was compared with that obtained with the test chamber.

• Ultraviolet-ozone jet cleaning process of organic surface contamination layers

DW Moon, A Kurokawa, S Ichimura, HW Lee, IC Jeon

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS   17 ( 1 ) 150 - 154  1999.01  [Refereed]

View Summary

To understand the ultraviolet (UV)-ozone jet cleaning process of organic surface contamination layers, adventitious hydrocarbon layers on Si, self-assembled octadecyltrichlorosilane monolayers on Si, and self-assembled C60H-(CH2)(12)-SH monolayers on Au were cleaned with pure ozone jet and UV irradiation. Cleaned surfaces were analyzed with in situ x-ray photoelectron spectroscopy measurements. Ozone molecules could react with the unsaturated C-C bonds in self-assembled C60H-(CH2)12-SH monolayers on Au surfaces at room temperature. However, the saturated C-C bonds in OTS hydrocarbon molecules adsorbed on Au surfaces reacted not with ozone molecules but with oxygen radicals generated by the dissociation of ozone molecules under UV irradiation. For adventitious carbon contamination on Si surfaces, only a fraction could be cleaned by ozone at room temperature but it could be almost cleaned with UV-ozone jet. (C) 1999 American Vacuum Society. [S0734-2101(99)02901-2].

K Nakamura, A Kurokawa, S Ichimura

SURFACE SCIENCE   402 ( 1-3 ) 165 - 169  1998.05  [Refereed]

View Summary

We observed by surface second harmonic generation (SHG) that initial the rate of second harmonics (SH) intensity decay during ozone adsorption on nitrogen-preadsorbed Si(111) was four times faster than on clean Si(111)-(7 x 7) because of the adsorption not only of atomic oxygen but also of oxygen molecules released by the dissociation of incident ozone molecules. The temperature dependence of the adsorption rate on nitrogen-adsorbed Si(111) was opposite to that on the clean Si(111)-(7 x 7) surface, but similar to that of molecular oxygen on Si(111)-(7 x 7). With increasing surface temperature, the sticking probability lessened in a similar way to that of molecular oxygen. This suggests that the sticking probability of molecular oxygen released by dissociating ozone molecules increases on nitrogen-adsorbed Si(111). (C) 1998 Elsevier Science B.V. All rights reserved.

• Ichimura Shingo

Materia Japan   37 ( 3 ) 166 - 170  1998

• K Kokubun, S Ichimura, M Hirata, S Sekine, A Kurokawa

VACUUM   48 ( 7-9 ) 727 - 729  1997.09

View Summary

In order to increase the ion-detection efficiency of pressure measurement using nonresonant laser ionization method, a Channeltron of aperture 19 mm was used in the ion-detection head and pressure measurement was carried out with H-2. The defection efficiency was increased about 1.5 times compared to a previous result. The volume of the ionization region estimated from the present measurement, 5.8 x 10(-4) mm(3), is close to that derived from the direct observation of the ion distribution in the ionization region, 6.4 x 10(-4) mm(3). (C) 1997 Elsevier Science Ltd.

• Comparison of initial oxidation of Si(111)7x7 with ozone and oxygen investigated by second harmonic generation

K Nakamura, A Kurokawa, S Ichimura

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS   15 ( 4 ) 2441 - 2445  1997.07  [Refereed]

View Summary

Initial oxidation by high purity ozone and molecular oxygen of Si(111)7x7 was investigated by second harmonic generation (SHG) with a 1.064 mu m Nd:YAG laser. Decrease of second harmonics (SH) intensity to almost zero after 5 L ozone gas exposure, in spite of the fact that molecular oxygen kept SH intensity for the same amount of exposure, indicated that ozone is inserted into the Si-Si backbond in the subsurface layers more effectively than molecular oxygen. In the initial exposure, rates of rapid decrease in SH intensity for both ozone and oxygen adsorption were in the same order of magnitude, although O 1s x-ray photoelectron spectroscopy (XPS) intensity showed high reactivity of ozone. This is because of a difference in the information depth between SHG and XPS so that oxygen species in the subsurface layers are not effective in decreasing SH intensity. This indicates that the process of attacking backbonds is underway even with an initial exposure of &lt;5 L. (C) 1997 American Vacuum Society.

• A new method for cleaning the surface of ultra high-purity iron by high-purity ozone exposure and UV irradiation

S Suzuki, S Ichimura, A Kurokawa, Y Ishikawa, M Isshiki, Y Waseda

MATERIALS TRANSACTIONS JIM   38 ( 5 ) 451 - 456  1997.05  [Refereed]

View Summary

A new method by applying high-purity ozone exposure and ultraviolet (UV) irradiation has been used for cleaning the surface of ultra high-purity iron with a carbon contaminated layer. The amount and chemical state of elements on the specimen surface were characterized by X-ray photoelectron spectroscopy. The intensity of the C 1s XPS peak due to carbon contamination was found to decrease with increasing ozone exposure al room temperature. UV irradiation during ozone exposure enhanced the cleaning rare. The XPS results show that contaminated carbon is mainly classified into major aliphatic carbon and minor carboxyl carbon, and their ratio depends upon the condition of ozone exposure. The role of ozone exposure and UV irradiation was discussed with respect to surface cleaning.

• Ken Nakamura, Akira Kurokawa, Shingo Ichimura

Surface and Interface Analysis   25   88 - 93  1997.02

View Summary

We observed an in situ process of ozone adsorption on Si(111)7 × 7 at different temperatures by second harmonic generation (SHG). On ozone exposure, the second harmonics (SH) intensity descreased close to a detectable limit on the surface at room temperature (RT). However, we observed the appearance of another SH intensity during ozone exposure at elevated substrate temperatures between 260 °C and 400 °C, after it decreased in the same way as that at RT. On these surfaces, the profile of SH intensity recovery by desorption of adsorbed species indicated that different adsorbed species were formed during surface exposure to ozone at different substrate temperatures: those at RT are weakly adsorbed species for termination of dangling bonds and insertion into backbonds, and those at higher temperatures have an Si-O-Si network which is more stable and desorbs at higher temperatures than 700 °C. We conclude that the SH intensity that appeared on the surfaces at elevated temperatures is due to more stable SiO2-like Si-O-Si bonding as an initial step of oxide formation. © 1997 by John Wiley &amp; Sons, Ltd.

• Analysis by surface-sensitive second harmonic generation of Si(111)7x7 exposed to high-purity ozone jet for oxide film formation

K Nakamura, A Kurokawa, S Ichimura

SURFACE AND INTERFACE ANALYSIS   25 ( 2 ) 88 - 93  1997.02  [Refereed]

View Summary

We observed an in situ process of ozone adsorption on Si(111)7 x 7 at different temperatures by second harmonic generation (SHG). On ozone exposure, the second harmonics (SH) intensity descreased close to a detectable limit on the surface at room temperature (RT). However, we observed the appearance of another SH intensity during ozone exposure at elevated substrate temperatures between 260 degrees C and 400 degrees C, after it decreased in the same way as that at RT. On these surfaces, the profile of SH intensity recovery by desorption of adsorbed species indicated that different adsorbed species were formed during surface exposure to ozone at different substrate temperatures: those at RT are weakly adsorbed species for termination of dangling bonds and insertion into backbonds, and those at higher temperatures have an Si-O-Si network which is more stable and desorbs at higher temperatures than 700 degrees C. We conclude that the SH intensity that appeared on the surfaces at elevated temperatures is due to more stable SiO2-like Si-O-Si bonding as an initial step of oxide formation. (C) 1997 by John Wiley & Sons, Ltd.

• Hoong-Sun Im, S. Ichimura

Applied Surface Science   108 ( 2 ) 197 - 204  1997

View Summary

Laser post-ionization sputtered neutral mass spectrometry (SNMS) has been applied to study the angular distribution of the sputtered constituents of Fe-40at%Cr alloys. Preferred Cr ejection was observed in the direction of the target normal under sputtering in atmosphere with a sufficient amount of oxygen gas, while there is no distinct difference in the angular dependence of the ratio of ejected components without oxygen. Comparing the results obtained by this method with those by the thin film deposition method, it is certified that the same results can be attained by both methods, although in-situ measurement of the angular distribution of the sputtered constituents is possible only by the laser SNMS method. This tendency is considered to be due to the formation of Fe segregated layers on the surface of the alloy by the presence of oxygen.

• ICHIMURA Shingo, NONAKA Hidehiko, KUROKAWA Akira, NAKAMURA Ken

Hyomen Kagaku   18 ( 12 ) 766 - 774  1997

View Summary

Fabrication of an ozone jet generator system and its application to the formation of ultra-thin silicon dioxide film was discussed. Superior features of using ozone and/or atomic oxygen in an oxidation process is highlighted through the comparison of reactivity among various oxidizing reagent, and also through the survey of their applications to SiO2 formation. Then the characteristics of the new ozone jet generator, which can supply high purity ozone flux and was specially designed to overcome the current problems in handling high purity ozone, was described in detail. Finally, the oxidation mechanism of Si with ozone, which was investigated by XPS and SHG methods, was discussed focusing on the role of atomic oxygen generated by the dissociation of ozone on silicon surface.

• High purity ozone oxidation on hydrogen passivated silicon surface

A Kurokawa, S Ichimura

APPLIED SURFACE SCIENCE   100   436 - 439  1996.07  [Refereed]

View Summary

High purity ozone was used to oxidize hydrogen passivated Si(111) surface. Initial oxide formation was investigated with X-ray photoelectron spectroscopy. The ozone oxidation was disturbed when the surface was gradually covered with hydrogen and finally the rate of oxide formation was reduced to one tenth when the surface was completely covered with hydrogen. This reduction rate is very small compared to the reduction rate for oxygen exposure which is reported to be 10(12). Ozone oxidation still proceeds on the hydrogen passivated surface where oxygen molecule does not adsorb at all. Three backbonds of a Si atom are changed to Si-O-Si bridges simultaneously when ozone oxidation proceeds on the hydrogen passivated surface.

• Ken Nakamura, Shingo Ichimura, Hazime Shimizu

Applied Surface Science   100-101   444 - 448  1996

View Summary

Oxygen adsorption was in situ observed by second harmonic generation (SHG) on both clean and hydrogen-preadsorbed Si(111)7 × 7. The sticking probability of molecular oxygen was decreased by monohydride formation, although it was not a completely passivating surface. This is a different effect of monohydride from that on Si(111)1 × 1 for passivation. Hydrogen adsorption at room temperature leading to both monohydride and polyhydride formation showed two different stages of sticking probability, with increasing exposure for hydrogen preadsorption, sticking probability was furthermore decreased with oxygen adsorption. This is expected due to the formation of polyhydride species on Si(111)7 × 7 which was found to be necessary for passivating reconstructed Si(111)7 × 7.

• S. Sekine, A. Iwasaki, A. Kurokawa, S. Ichimura, K. Kokubun, H. Shimizu

Vacuum   47   553 - 555  1996.01

View Summary

The second harmonic of a picosecond Nd:YAG laser was used to nonresonantly ionize Xe atoms in vacuum. The spatial distribution of the produced ions was observed by our ion-imaging method. Time of flight spectrum of the produced ions was also measured simultaneously. Xe2+and Xe3+ions were detected around the center of the ionization volume. The produced amount of multiply charged ions decreased rapidly with the distance from the center of ionization volume comparing to that of Xe+ions. The present method can be applied for the simultaneous measurement of total and partial pressure. Copyright © 1996 Elsevier Science Ltd.

• K. Kokubun, S. Sekine, S. Ichimura, A. Kurokawa, H. Shimizu

Vacuum   47   557 - 559  1996.01

View Summary

In order to increase the ion-detection efficiency of the pressure measurement method using nonresonant multiphoton ionization, an ion-detection head was improved. Using this head, pressure measurements were carried out for H2and Xe in the extreme high vacuum region. As a result, for H2, by optimizing an incident ion energy, the efficiency increased by a factor of about 2.5. For Xe, without optimizing the incident ion energy, it increased by a factor of about 1.5. Copyright © 1996 Elsevier Science Ltd.

• S Sekine, S Ichimura

REVIEW OF SCIENTIFIC INSTRUMENTS   67 ( 1 ) 325 - 327  1996.01

View Summary

An electron/ion pulse counting system was used for a high-counting-rate application under strong electromagnetic noise. The number of photoelectrons produced by a nonresonant multiphoton ionization of gaseous molecules was counted as a function of gas pressure in vacuum. The system was successfully operated under electromagnetic noise originated from a pulsed laser. The detector acted as a gated, accumulating counter with a capacity of 300 cps. A maximum counting rate of 2 X 10(10) cps was experimentally achieved when laser-produced photoelectrons arrived within a gate of 15 ns. (C) 1996 American Institute of Physics.

• S. Ichimura, K. Kokubun, H. Shimizu, S. Sekine

Vacuum   47   545 - 552  1996.01

View Summary

The current status and possibility of XHV measurement by laser ionization using second harmonics of a picosecond YAG laser are discussed. Under the condition that incident laser energy was 30 mJ/pulse and the laser beam was focused with a spherical lens (focal length f= 250mm) to a power density sufficient for the saturation Of H2ionization at the focal point, the minimum pressure in an XHV chamber was measured. From the minimum pressure estimated by extrapolation (5 × 10-11Pa) and the ion counting rate at that pressure (one count during 500 laser shots), the volume of the ionization region was expected to be 1.7 × 10-4mm3. The ionization region was then measured experimentally under the same laser beam conditions. It was found that the ionization region has a spindle shape with maximum diameter of 45 μm and the length of 1.2mm. The estimated volume is larger than the expected volume by a factor between 4 and 12. The ion detection efficiency of the electron multiplier is one of the major factors affecting the difference, and it can be reduced to within a factor of 3. On the basis of the results, the possibility of absolute measurement of XHV pressure by laser ionization is discussed. Copyright © 1996 Published by Elsevier Science Ltd.

• Shigeo Tanuma, Shingo Ichimura, Kazuhiro Yoshihara

Applied Surface Science   100-101   47 - 50  1996

View Summary

We have calculated the effective inelastic mean free paths (EIMFPs) for electrons in some elemental solids
i.e. Li, Na, K, Rb, Al, Si, Cu, Ag, and Au in the range 50-2000 eV using Monte Carlo simulation. We defined the effective inelastic mean free path as the straight distance between two successive inelastic collisions. This quantity is independent on the experimental configuration. In conclusion, the values of EIMFP could be expressed as γ × λ, where γ is a coefficient of the effect of the elastic scattering and λ the inelastic mean free path, in the range 100-2000 eV for all calculated elements. The γ values obtained from the calculations were 0.85-1.0. Above the 1000 eV region for alkali metals, Al and Si, we could ignore the effect of the elastic scattering because the γ values were larger than 0.95. We could not determine the γ values for Au and Ag in the range 50-100 eV because their intensities of the signals calculated by the Monte Carlo method did not vary exponentially with the distance between two successive inelastic collisions.

• SATOH Hitomi, TANAKA Akihiro, ICHIMURA Singo, JO Masatoshi, TANUMA Sigeo, YOSHIHARA Kazuhiro

Hyomen Kagaku   17 ( 8 ) 480 - 482  1996

View Summary

In this study, the authors measured the ratio of the peak area of photoelectrons from s-orbitals to that of the p-orbitals for six elements (Al, Si, Cu, Mo, Ag and Au) resulting in eight s : p ratios. We used two angles (90&deg; and 54.7&deg;) between the incident X-ray beam and the photoelectron detector to investigate elastic scattering effects on the distribution of photoemission from the samples. The data obtained were compared to calculated values. When elastic scattering effects are accounted for, the ratio of s- to p-orbitals by XPS should be independent of angle. The experimental results from five of the eight elemental ratios showed this angular independence. We believe that other effects, such as electron diffraction, will be need to be considered in order to get complete agreement.

• X-ray photoelectron spectroscopy (XPS) analysis of oxide formation on silicon with high-purity ozone

A Kurokawa, S Ichimura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   34 ( 12A ) L1606 - L1608  1995.12  [Refereed]

View Summary

Initial oxide formation on a Si(111) surface with high-purity ozone (more than 80% ozone concentration at the sample position) is investigated by X-ray photoelectron spectroscopy (XPS). The suboxide formed by oxidation is characterized from Si-2p spectra. From the comparison of the suboxides formed with ozone and oxygen exposures, it is clear that ozone forms less suboxide than oxygen. Ozone oxidizes a monohydride Si surface, which oxygen does not oxidize appreciably.

• ADSORPTION AND THERMAL OR PHOTODECOMPOSITION OF TRIETHYLGALLIUM AND TRIMETHYLGALLIUM ON SI(111)-7X7

K FUKUI, W MIZUTANI, H ONISHI, S ICHIMURA, H SHIMIZU, Y IWASAWA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 9A ) 4910 - 4916  1995.09

View Summary

Adsorption and thermal or photodecomposition of triethylgallium (TEG) and trimethylgallium (TMG) on Si(lll)-7 x 7 were investigated using a home-built scanning tunneling microscope (STM), Auger electron spectroscopy (AES), and thermal desorption spectroscopy (TDS). Adsorption of TEG and TMG at room temperature gave bright protrusions of Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) (x = 2, 3) on atop sites of Si adatoms with a slight preference for center adatoms over comer ones. The Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) species were decomposed by UV irradiation probably due to absorption of UV photons by these adsorbates. Thermal decomposition of TEG on the 7 x 7 surface led to severe carbon deposition, particularly at low initial coverage of TEG, in contrast to the result reported on Si(100)-2 x 1.

• ADSORPTION AND THERMAL OR PHOTODECOMPOSITION OF TRIETHYLGALLIUM AND TRIMETHYLGALLIUM ON SI(111)-7X7

K FUKUI, W MIZUTANI, H ONISHI, S ICHIMURA, H SHIMIZU, Y IWASAWA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 9A ) 4910 - 4916  1995.09

View Summary

Adsorption and thermal or photodecomposition of triethylgallium (TEG) and trimethylgallium (TMG) on Si(lll)-7 x 7 were investigated using a home-built scanning tunneling microscope (STM), Auger electron spectroscopy (AES), and thermal desorption spectroscopy (TDS). Adsorption of TEG and TMG at room temperature gave bright protrusions of Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) (x = 2, 3) on atop sites of Si adatoms with a slight preference for center adatoms over comer ones. The Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) species were decomposed by UV irradiation probably due to absorption of UV photons by these adsorbates. Thermal decomposition of TEG on the 7 x 7 surface led to severe carbon deposition, particularly at low initial coverage of TEG, in contrast to the result reported on Si(100)-2 x 1.

• ADSORPTION AND THERMAL OR PHOTODECOMPOSITION OF TRIETHYLGALLIUM AND TRIMETHYLGALLIUM ON SI(111)-7X7

K FUKUI, W MIZUTANI, H ONISHI, S ICHIMURA, H SHIMIZU, Y IWASAWA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 9A ) 4910 - 4916  1995.09  [Refereed]

View Summary

Adsorption and thermal or photodecomposition of triethylgallium (TEG) and trimethylgallium (TMG) on Si(lll)-7 x 7 were investigated using a home-built scanning tunneling microscope (STM), Auger electron spectroscopy (AES), and thermal desorption spectroscopy (TDS). Adsorption of TEG and TMG at room temperature gave bright protrusions of Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) (x = 2, 3) on atop sites of Si adatoms with a slight preference for center adatoms over comer ones. The Ga(C2H5)(x)(a) and Ga(CH3)(x)(a) species were decomposed by UV irradiation probably due to absorption of UV photons by these adsorbates. Thermal decomposition of TEG on the 7 x 7 surface led to severe carbon deposition, particularly at low initial coverage of TEG, in contrast to the result reported on Si(100)-2 x 1.

• 一村信吾

高圧ガス   32 ( 2 ) 154 - 158  1995.02

• APPLICATION OF STM NANOMETER-SIRE OXIDATION PROCESS TO PLANAR-TYPE MIM DIODE

K MATSUMOTO, S TAKAHASHI, M ISHII, M HOSHI, A KUROKAWA, S ICHIMURA, A ANDO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 2B ) 1387 - 1390  1995.02

View Summary

Ultra fine oxidized titanium (Ti) lines 18 nm wide and 3 nm high have been formed on the surface of a 4 nm Ti layer on a SiO2/Si substrate using the scanning tunneling microscope [STM] tip as-a selective anodization electrode. The dependence of the size of the oxidized titanium line on the various parameters is investigated. The formed oxidized titanium line has resistivity of 2 x 10(4) ohm cm, which is a value seven orders of magnitude higher than that of the deposited Ti layer. The oxidized Ti line is used in the planar type metal-insulator-metal [MIM] diode, and works as an energy barrier for the electron. The energy barrier height of the oxidized Ti line is found to be delta E(g) = 0.25 eV.

• APPLICATION OF STM NANOMETER-SIRE OXIDATION PROCESS TO PLANAR-TYPE MIM DIODE

K MATSUMOTO, S TAKAHASHI, M ISHII, M HOSHI, A KUROKAWA, S ICHIMURA, A ANDO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 2B ) 1387 - 1390  1995.02

View Summary

Ultra fine oxidized titanium (Ti) lines 18 nm wide and 3 nm high have been formed on the surface of a 4 nm Ti layer on a SiO2/Si substrate using the scanning tunneling microscope [STM] tip as-a selective anodization electrode. The dependence of the size of the oxidized titanium line on the various parameters is investigated. The formed oxidized titanium line has resistivity of 2 x 10(4) ohm cm, which is a value seven orders of magnitude higher than that of the deposited Ti layer. The oxidized Ti line is used in the planar type metal-insulator-metal [MIM] diode, and works as an energy barrier for the electron. The energy barrier height of the oxidized Ti line is found to be delta E(g) = 0.25 eV.

• Shigeyuki Sekine, Hazime Shimizu, Shingo Ichimura

Applied Surface Science   84 ( 4 ) 401 - 406  1995

View Summary

Polycrystalline CuNi alloys were sputtered by 3 kV Xe+ ions at elevated temperatures to analyze the ion-beam-induced diffusion. The time evolution of the composition of the sputtered materials from the start of the sputtering was measured by TOF-SNMS (time-of-flight sputtered neutral mass spectrometry). During removal of the Gibbsian segregation layer of copper, the sputtered flux consisted of almost only copper atoms. Then, the copper content gradually decreased due to the formation of a sputter-induced copper-depleted surface layer, and reached an almost steady state with still higher copper content than the bulk composition. From the temperature dependence of the composition at the quasi-steady state the activation energy of copper transportation through a high diffusivity path was derived to be 54 kJ mol-1 (0.56 eV). The high diffusivity path was assigned to copper diffusion through grain boundaries. © 1995.

• Akira Kurokawa, Shingo Ichimura, Jae Jeong, Joseph Toth, Kazuhiro Yoshihara, Yoshio Saitoh, Yoshihiro Satoh

Shinku   38 ( 3 ) 179 - 182  1995

• Development of oxidation sources in preparation of high-T-c oxide superconductor thin films using the molecular beam epitaxy method

H Nonaka, S Ichimura, T Shimizu, K Arai

CRITICAL REVIEWS IN SOLID STATE AND MATERIALS SCIENCES   20 ( 4 ) 285 - 338  1995  [Refereed]

View Summary

Film preparation of oxide superconductors, mainly of the 1-2-3 (RBa(2)Cu(3)O(x)) and Bi-containing (Bi-Sr-Ca-Cu-O) systems, by evaporation of either metals or metal compounds by low pressure is summarized, with a particular focus on the development of oxidation sources essential to the technique. Oxidizing reagents that enable the oxidation of metal evaporates to take place in high (0.1 to 10(-3) Pa) or even ultra-high (&lt;10(-5) Pa) vacuum are summarized using the experiments of those who tried to apply the molecular beam epitaxy method to atomically controlled fabrication of thin films of the material, especially for device processing. The evaporation in various kinds of oxidizing atmosphere, including the simple method of in situ annealing of the metal layers in oxygen to the more advanced in situ preparation of the films with strong oxidizing reagents such as atomic oxygen, ozone, nitric oxide, etc. along with the thermochemistry of the oxidation of metals by low pressure with these reagents is reviewed.

• ANNEALING BEHAVIOR OF IRRADIATION-INDUCED DAMAGE IN AN ALGAAS/GAAS HETEROSTRUCTURE BY LOW-ENERGY-ELECTRON BEAM

T WADA, T KANAYAMA, S ICHIMURA, Y SUGIYAMA, M KOMURO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   33 ( 12B ) 7228 - 7231  1994.12

View Summary

Evaluating the low-temperature mobility of the tyro-dimensional electron gas in AlGaAs/GaAs heterostructures, we have studied the nature of the damage induced in the heterostructure by low-energy electron-beam irradiation up to 7.5 keV at room temperature and at 90 K. The isochronal annealing revealed that at around 450 K the degraded mobility recovered quickly in the 90-K-irradiated sample and gradually in the sample irradiated at room temperature. However, the quality of both samples did not recover completely upon annealing at 675 K. The electron-beam irradiation was speculated to cause the formation of As-related defects.

• PRELIMINARY MEASUREMENT OF H-2 PRESSURE THROUGH DETECTION OF PHOTOELECTRONS IN VACUUM RANGE FROM 10(-3) TO 10(-6) PA

S SEKINE, K KOKUBUN, S ICHIMURA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   33 ( 9A ) L1274 - L1276  1994.09

View Summary

H-2 molecules in a vacuum chamber were nonresonantly ionized by an intense visible laser pulse, and the number of photoelectrons produced was measured as a function of H-2 pressure. The signal intensity was proportional to H-2 pressure in the range from 1 x 10(-3) to 1 x 10(-6) Pa. The present result showed experimentally that the detection of laser-induced photoelectrons can be applied for the measurement of pressure in the ultrahigh-vacuum range.

• PRELIMINARY MEASUREMENT OF H-2 PRESSURE THROUGH DETECTION OF PHOTOELECTRONS IN VACUUM RANGE FROM 10(-3) TO 10(-6) PA

S SEKINE, K KOKUBUN, S ICHIMURA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   33 ( 9A ) L1274 - L1276  1994.09

View Summary

H-2 molecules in a vacuum chamber were nonresonantly ionized by an intense visible laser pulse, and the number of photoelectrons produced was measured as a function of H-2 pressure. The signal intensity was proportional to H-2 pressure in the range from 1 x 10(-3) to 1 x 10(-6) Pa. The present result showed experimentally that the detection of laser-induced photoelectrons can be applied for the measurement of pressure in the ultrahigh-vacuum range.

• EFFECT OF OPTICAL-BREAKDOWN ON 2ND-HARMONIC GENERATION FROM SI(111)7X7 WITH NDYAG LASER

K NAKAMURA, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   33 ( 7B ) L1035 - L1037  1994.07

View Summary

Effect of optical breakdown on second harmonic generation (SHG) from Si(111)7 x 7 was investigated. After the irradiation of a laser beam with a threshold energy for the optical breakdown, the intensity of second harmonics (SH) polarized along the [011BAR] axis measured as a function of pump-polarization showed deviation from 90-degrees periodicity which is expected from the surface C3v symmetry, although low energy electron diffraction (LEED) still exhibited the 7 x 7 structure. The irradiation of a more intense laser beam led to structural disorder, resulting in complete disappearance of SH periodicity, and no pattern of LEED was exhibited.

• EFFECT OF OPTICAL-BREAKDOWN ON 2ND-HARMONIC GENERATION FROM SI(111)7X7 WITH NDYAG LASER

K NAKAMURA, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   33 ( 7B ) L1035 - L1037  1994.07

View Summary

Effect of optical breakdown on second harmonic generation (SHG) from Si(111)7 x 7 was investigated. After the irradiation of a laser beam with a threshold energy for the optical breakdown, the intensity of second harmonics (SH) polarized along the [011BAR] axis measured as a function of pump-polarization showed deviation from 90-degrees periodicity which is expected from the surface C3v symmetry, although low energy electron diffraction (LEED) still exhibited the 7 x 7 structure. The irradiation of a more intense laser beam led to structural disorder, resulting in complete disappearance of SH periodicity, and no pattern of LEED was exhibited.

• EXCIMER-LASER ABLATION OF CRYOGENIC NO2 FILMS

S SEKINE, S ICHIMURA, H SHIMIZU, H HASHIZUME

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   33 ( 3A ) L387 - L389  1994.03

View Summary

Cryogenic NO2 films were ablated by a XeCl excimer laser. Only NO2 molecules were detected by a time-of-flight method. Velocity distribution of ablated NO2 molecules was found to be almost thermal. The derived temperature of the fitted Maxwell-Boltzmann distributions depended on the thickness of cryogenic NO2 film in the range from 300 K to 1100 K. The fastest NO2 observed in the present experiment had a translational energy of 0.5 eV.

• 一村信吾

ぶんせき   ( 2 ) 88 - 96  1994.02

• Shigeyuki Sekine, Kiyohide Kokubun, Shingo Ichimura

Japanese Journal of Applied Physics   33 ( 9 ) L1274 - L1276  1994

View Summary

H2 molecules in a vacuum chamber were nonresonantly ionized by an intense visible laser pulse, and the number of photoelectrons produced was measured as a function of H2 pressure. The signal intensity was proportional to H2 pressure in the range from 1 × 10–3 to 1 × 10–6 Pa. The present result showed experimentally that the detection of laser-induced photoelectrons can be applied for the measurement of pressure in the ultrahigh-vacuum range. © 1994 IOP Publishing Ltd.

• Shigeyuki Sekine, Shingo Ichimura, Hazime Shimizu, Hiroko Hashizume

Japanese Journal of Applied Physics   33 ( 3 ) L387 - L389  1994

View Summary

Cryogenic NO2 films were ablated by a XeCl excimer laser. Only NO2 molecules were detected by a time-of-flight method. Velocity distribution of ablated NO2 molecules was found to be almost thermal. The derived temperature of the fitted Maxwell-Boltzmann distributions depended on the thickness of cryogenic NO2 film in the range from 300 K to 1100 K. The fastest NO2 observed in the present experiment had a translational energy of 0.5 eV. © 1994 The Japan Society of Applied Physics.

• S ICHIMURA, S SEKINE, HJ STEFFEN, K KOKUBUN, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   33 ( 1B ) L135 - L138  1994.01

View Summary

The spatial distribution of ions generated by nonresonant multiphoton ionization (NRMPI) of H-2 gas with a picosecond YAG laser was clearly observed with a new detection system consisted of a static lens, a microchannel plate (MCP) intensifier, a charge-coupled device (CCD) camera, and an image processor. The ions were distributed along a straight line, reflecting the ion generation along the laser beam path. The ionization region had a spindle shape with the maximum diameter at the focal point of a spherical lens used for laser beam focussing. The size of the ionization region was about 2.5 mm in length and 0.05 mm in diameter when the gas pressure was 1 x 10(-5) Pa and incident laser energy was 12 mJ/pulse. The laser power density at the focal point was about 2 x 10(13) W/cm(2).

• Toshimi Wada, Toshihiko Kanayama, Shingo Ichimura, Yoshinobu Sugiyama, Masanori Komuro

Japanese Journal of Applied Physics   33 ( 12S ) 722 - 721  1994

View Summary

Evaluating the low-temperature mobility of the two-dimensional electron gas in AlGaAs/GaAs heterostructures, we have studied the nature of the damage induced in the heterostructure by low-energy electron-beam irradiation up to 7.5 keV at room temperature and at 90 K. The isochronal annealing revealed that at around 450 K the degraded mobility recovered quickly in the 90-K-irradiated sample and gradually in the sample irradiated at room temperature. However, the quality of both samples did not recover completely upon annealing at 675 K. The electron-beam irradiation was speculated to cause the formation of As-related defects. © 1994 IOP Publishing Ltd.

• S. Ichimura, S. Sekine, K. Kokubun, H. Shimizu

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films   12 ( 4 ) 1734 - 1739  1994

View Summary

The spatial distribution of ions generated by nonresonant multiphoton ionization of Xe and H2with second harmonics of a picosecond YAG laser was imaged with a new detection system. Ions were observed as bright spots on a microchannel plate (MCP) intensifier and they appeared on a straight line, reflecting the ion generation along a laser beam path. The size of the ionization region, which has a spindle shape, was estimated from the image. The maximum diameter of the ionization region was ~60 μm, and the length was 3.6 mm for a Xe gas pressure of 5 X 10—5 Pa and an incident laser energy of 10 mJ/pulse for our measurement system. The size depended on the incident laser energy, and on the lens assembly used for the focusing of the laser beam, The possibility of relative pressure measurement by counting of the bright spot on the MCP intensifier was also investigated. © 1994, American Vacuum Society. All rights reserved.

• DIRECT IMAGING OF SPATIAL-DISTRIBUTION OF IONS GENERATED BY NONRESONANT MULTIPHOTON IONIZATION OF H-2 GAS

S ICHIMURA, S SEKINE, HJ STEFFEN, K KOKUBUN, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   33 ( 1B ) L135 - L138  1994.01

View Summary

The spatial distribution of ions generated by nonresonant multiphoton ionization (NRMPI) of H-2 gas with a picosecond YAG laser was clearly observed with a new detection system consisted of a static lens, a microchannel plate (MCP) intensifier, a charge-coupled device (CCD) camera, and an image processor. The ions were distributed along a straight line, reflecting the ion generation along the laser beam path. The ionization region had a spindle shape with the maximum diameter at the focal point of a spherical lens used for laser beam focussing. The size of the ionization region was about 2.5 mm in length and 0.05 mm in diameter when the gas pressure was 1 x 10(-5) Pa and incident laser energy was 12 mJ/pulse. The laser power density at the focal point was about 2 x 10(13) W/cm(2).

• KOKUBUN Kiyohide, ICHIMURA Shingo, SEKINE Shigeyuki, SHIMIZU Hazime

OYOBUTURI   63 ( 12 ) 1239 - 1242  1994

• EFFECTS OF ELECTRON-IRRADIATION ON 2-DIMENSIONAL ELECTRON-GAS IN ALGAAS/GAAS HETEROSTRUCTURE

T WADA, T KANAYAMA, S ICHIMURA, Y SUGIYAMA, S MISAWA, M KOMURO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   32 ( 12B ) 6262 - 6267  1993.12

View Summary

This paper describes how the two-dimensional electron gases in AlGaAs/GaAs heterostructures are degraded by low-energy electron irradiation. Both the electron mobility and the two-dimensional carriers are shown to decrease considerably by a 1 X 10(17)/cm2 irradiation with the incident electron energy of 8 keV. Comparing the experimental results both with the Monte Carlo simulation and with the theoretical mobility calculation, we speculated that the mobility degradation and the 2D carrier compensation are partly caused by the formation of complex defects in the GaAs buff er layer which are due to the excitations of core electrons of As and that the mobility is further degraded by the formation of short-range scatterers in the AlGaAs/GaAs heterointerface.

• EFFECTS OF ELECTRON-IRRADIATION ON 2-DIMENSIONAL ELECTRON-GAS IN ALGAAS/GAAS HETEROSTRUCTURE

T WADA, T KANAYAMA, S ICHIMURA, Y SUGIYAMA, S MISAWA, M KOMURO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   32 ( 12B ) 6262 - 6267  1993.12

View Summary

This paper describes how the two-dimensional electron gases in AlGaAs/GaAs heterostructures are degraded by low-energy electron irradiation. Both the electron mobility and the two-dimensional carriers are shown to decrease considerably by a 1 X 10(17)/cm2 irradiation with the incident electron energy of 8 keV. Comparing the experimental results both with the Monte Carlo simulation and with the theoretical mobility calculation, we speculated that the mobility degradation and the 2D carrier compensation are partly caused by the formation of complex defects in the GaAs buff er layer which are due to the excitations of core electrons of As and that the mobility is further degraded by the formation of short-range scatterers in the AlGaAs/GaAs heterointerface.

• PRELIMINARY PRESSURE MEASUREMENT IN THE RANGE OF 10(-9) PA USING A PICOSECOND PULSED-LASER

K KOKUBUN, S SEKINE, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 9B ) L1368 - L1369  1993.09

View Summary

Results of the preliminary pressure measurement using a picosecond pulsed YAG laser are presented. By this method, pressures in the range of 10(-9) Pa were measured for H-2 gas. Advantages of this method and the problem of noise are discussed compared with the method using an excimer laser.

• NONRESONANT MULTIPHOTON IONIZATION OF H2, CO AND CO-2 BY 2ND HARMONICS OF PICOSECOND YAG LASER

S SEKINE, K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 9A ) L1284 - L1285  1993.09

View Summary

A nonresonant multiphoton ionization method has been applied for pressure measurement in ultrahigh vacuum. Second harmonics of a commercial picosecond YAG laser was used for ionization of gases in order to reduce noise caused by scattered laser light. Saturation of ionization was observed for H-2, CO and CO2 gases at incident laser power density of about 10(13) W.cm-2.

• PRELIMINARY PRESSURE MEASUREMENT IN THE RANGE OF 10(-9) PA USING A PICOSECOND PULSED-LASER

K KOKUBUN, S SEKINE, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 9B ) L1368 - L1369  1993.09

View Summary

Results of the preliminary pressure measurement using a picosecond pulsed YAG laser are presented. By this method, pressures in the range of 10(-9) Pa were measured for H-2 gas. Advantages of this method and the problem of noise are discussed compared with the method using an excimer laser.

• NONRESONANT MULTIPHOTON IONIZATION OF H2, CO AND CO-2 BY 2ND HARMONICS OF PICOSECOND YAG LASER

S SEKINE, K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 9A ) L1284 - L1285  1993.09

View Summary

A nonresonant multiphoton ionization method has been applied for pressure measurement in ultrahigh vacuum. Second harmonics of a commercial picosecond YAG laser was used for ionization of gases in order to reduce noise caused by scattered laser light. Saturation of ionization was observed for H-2, CO and CO2 gases at incident laser power density of about 10(13) W.cm-2.

• MEASUREMENT OF EXTREME-HIGH-VACUUM PRESSURE BY LASER IONIZATION

K KOKUBUN, S ICHIMURA, S SEKINE, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 8A ) L1109 - L1111  1993.08

View Summary

Measurement of gas pressure using nonresonant multiphoton ionization has been performed. As a result, extreme-high-vacuum (XHV) pressure to 7 X 10(-10) Pa was successfully measured by this method. The experimental results are presented, and problems related to noise are discussed.

• MEASUREMENT OF EXTREME-HIGH-VACUUM PRESSURE BY LASER IONIZATION

K KOKUBUN, S ICHIMURA, S SEKINE, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   32 ( 8A ) L1109 - L1111  1993.08

View Summary

Measurement of gas pressure using nonresonant multiphoton ionization has been performed. As a result, extreme-high-vacuum (XHV) pressure to 7 X 10(-10) Pa was successfully measured by this method. The experimental results are presented, and problems related to noise are discussed.

• K Kokubun, S Ichimura, H Shimizu, S Sekine

Vacuum   44 ( 5-7 ) 657 - 659  1993

View Summary

A pressure measurement method for xhv using laser ionization has been developed. By means of nonresonant multiphonon ionization, the proportional relation between the amount of laser-generated ions and the gas pressure is experimentally verified in the range 1 × 10-3-2 × 10-8 Pa. Also, a nonresonant 4-photon ionization of the He atom, which has the highest ionization potential of all atoms and molecules, and saturations of ionization for Xe, Kr, O2 and especially for H2, which is a main residual molecule in uhv and xhv, are successfully observed. In addition, a high-sensitivity ion-detection system for the exact measurement of several atoms and molecules in xhv is prepared. Noise due to scattered laser light is discussed. © 1993.

• Hidehiko Nonaka, Takashi Shimizu, Shingo Ichimura, Kazuo Arai

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films   11 ( 5 ) 2676 - 2680  1993

View Summary

The reflection high-energy electron diffraction beam excited Auger electron spectroscopy (AES) was applied to in situ and real time observation of the growing surface of films during molecular-beam epitaxy deposition. A compact electron energy analyzer assembly which consists of an einzel lens, sector-type energy analyzer, microchannel plate detector, and magnetic shielding case was built to enable the measurement close to the substrate without disturbing the deposition. The system was checked by the in situ AES measurement of crystals surface during cleaning with ozone. The technique is applicable to analyze in situ the growing surface of more complicated materials such as oxide superconductors whose microstructures at an atomic level must be well controlled for better quality and for use in microelectronic devices such as the Josephson junction. © 1993, American Vacuum Society. All rights reserved.

• Kiyohide Kokubun, Sigeyuki Sekine, Shingo Ichimura, Hazime Shimizu

Japanese Journal of Applied Physics   32 ( 9 ) L1368 - L1369  1993

View Summary

Results of the preliminary pressure measurement using a picosecond pulsed YAG laser are presented. By this method, pressures in the range of 10-9 Pa were measured for H2 gas. Advantages of this method and the problem of noise are discussed compared with the method using an excimer laser. © 1993 The Japan Society of Applied Physics.

• Shigeyuki Sekine, Kiyohide Kokubun, Shingo Ichimura, Hazime Shimizu

Japanese Journal of Applied Physics   32 ( 9 ) L1284 - L1285  1993

View Summary

A nonresonant multiphoton ionization method has been applied for pressure measurement in ultrahigh vacuum. Second harmonics of a commercial picosecond YAG laser was used for ionization of gases in order to reduce noise caused by scattered laser light. Saturation of ionization was observed for H2, CO and CO2 gases at incident laser power density of about 1013 Wƃcm-2. © 1993 The Japan Society of Applied Physics.

• OXIDATION IN PREPARATION OF OXIDE SUPERCONDUCTING FILMS BY MBE USING NO2 AND O-3 GASES

H NONAKA, T SHIMIZU, S HOSOKAWA, S ICHIMURA, K ARAI

SURFACE AND INTERFACE ANALYSIS   19 ( 1-12 ) 353 - 357  1992.06  [Refereed]

View Summary

In order to prepare oxide superconducting films by molecular beam epitaxy (MBE), we developed a compact NO2 supersonic molecular beam source and a new ozone jet generator to supply oxidizing gases with high controllability. Using these sources, oxide superconducting films of REBa2CU3Ox (RE = Nd, Y) were prepared on either MgO or SrTiO3 substrates Because of the sufficiently low pressure during deposition, the oxidation process of the metals, especially of copper, by the oxidizing gases and the crystallization and surface flatness of the films were studied in situ by XPS and reflection high-energy electron diffraction (RHEED) together with effective cleaning of the substrates by the oxidizing gases.

• PREPARATION OF OXIDE SUPERCONDUCTING FILMS IN MBE USING NO2 AND O-3 GASES

T SHIMIZU, H NONAKA, S HOSOKAWA, S ICHIMURA, K ARAI

PHYSICA C   185   2003 - 2004  1991.12  [Refereed]

View Summary

Thin films of YBa2Cu3O7-delta (BCO) were prepared in MBE with two types of oxidizing gases. One is a NO2 supersonic molecular beam which is well collimated NO2 beam with a high flux density. The other is a high purity ozone gas with good controllability in flux density. Using RHEED during deposition we observed growth behaviors of YBCO with each oxidizing gas. The RHEED intensity oscillations under coevaporation conditions suggest unit by unit growth of YBCO. The overall RHEED oscillation with period of c-axis unit was observed during sequential deposition with O3.

• Shunsuke Hosokawa, Shingo Ichimura

Review of Scientific Instruments   62 ( 6 ) 1614 - 1619  1991

View Summary

An ozone jet generator to supply precisely controlled ozone flux to a specimen was constructed with the particular aim of its application for the preparation of superconducting oxide thin films by an MBE (molecular beam epitaxy) method. The ozone jet is supplied to the thin film growth chamber by evaporating the liquid (or solid) ozone accumulated in the ozone vessel of the generator. The necessary condensed ozone is produced from the ozone-oxygen mixture gas generated by a commercial ozonizer. The ozone flux can be changed by adjusting the temperature of the ozone vessel (i.e., the temperature of liquid ozone). Precise pressure and temperature control of the ozone vessel in liquefying ozone makes it possible to minimize dissolution of diatomic oxygen in the liquid ozone. As a result, the ozone jet generated from the liquid ozone possesses high purity. The precise temperature control also enables a very stable supply of the ozone jet, with a stability of less than 2.5% over 1.5 h. For the experimental condition of liquefying ozone at 95 K and 800 Pa, and evaporating at 85 K, an ozone jet with an ozone flux of 1×10 16 molecules/s and an ozone concentration of higher than 70% was obtained in the test vacuum chamber installed with this ozone jet generator. It was also confirmed by XPS spectra of Cu after oxide film formation that the ozone jet possesses a very high reactivity.

• S. Ichimura, S. Hosokawa, H. N. Nonaka, K. Arai

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films   9 ( 4 ) 2369 - 2373  1991

View Summary

The quality of ozone vapor produced with a new ozone generator was evaluated. The ozone vapor was produced by evaporation of liquid ozone after accumulating it in a ozone vessel at various temperatures between 75 and 95 K. Mass analysis of the ozone vapor revealed that the purity of ozone in the vapor depended on both the ozone vessel temperature during liquefaction and that during evaporation. The purity was — 70% when liquid ozone accumulation temperatures higher than 90 K were used. The activity of the ozone vapor was investigated by oxidation of a Cu foil under low pressure condition. The formation of a CuO layer by exposure to the ozone vapor (pressure: ~5X 10-4Pa) at 300°C was confirmed through x-ray photoelectron spectroscopy analysis. © 1991, American Vacuum Society. All rights reserved.

• HASHIZUME Hiroko, ICHIMURA Shingo, SHIMIZU Hajime

Hyomen Kagaku   12 ( 2 ) 103 - 109  1991

View Summary

Laser induced neutral particle emission was observed. When Al surface was irradiated by a Q-switched YAG 532nm beam with energy density below 2J&middot;cm-2, only neutral atoms were detected. The amount of ejected atoms and their kinetic energies were measured as a function of laser fluence. Both the results indicate that increase of the surface temperature exceeds several thousands Kelvin, and the mechanism of atom emission around this energy region follows statistical thermodynamics.

• Yoshihara Kazuhiro, Ichimura Shingo

Bulletin of the Japan Institute of Metals   30 ( 7 ) 595 - 600  1991

• ICHIMURA Shingo, GOTO Keisuke

Hyomen Kagaku   12 ( 6 ) 367 - 374  1991

• S. Ichimura, H. Shimizu, K. Kokuban, H. Hashizume, K. Goto

Vacuum   41   1788 - 1789  1990.12

View Summary

In sputtered neutrals mass spectrometry (SNMS) with a laser for post-ionization a bunch of ions is generated within a short period corresponding to a laser pulse width (typically, a few tens of nanoseconds). The number of ions exceeds 100 under some conditions, so that a peak counting ability close to 1010is necessary to detect all of them. The authors used an analog detection system for this purpose, but it was found to suffer from signal fluctuation, particularly when the primary ion beam current was low. They therefore developed a new counting system in which a bunch of ions incident on a microchannel plate is converted into photoradiating spots on a fluorescent screen. A charge coupled device camera records these spots and accumulates the signal for a (shutter opening) period. The signal is then transferred to a frame memory. Subsequently, a personal computer counts the &#039;events&#039; in the frame memory.

• S TANUMA, T SEKINE, K YOSHIHARA, R SHIMIZU, T HOMMA, H TOKUTAKA, K GOTO, M UEMURA, D FUJITA, A KUROKAWA, S ICHIMURA, C OSHIMA, M KURAHASHI, M KUDO, Y HASHIGUCHI, T SUZUKI, T OHMURA, F SOEDA, K TANAKA, A TANAKA, Y SHIOKAWA, T HAYASHI

SURFACE AND INTERFACE ANALYSIS   15 ( 8 ) 466 - 472  1990.08

View Summary

A matrix effect correction is required to improve the accuracy of quantitative AES analysis. The correction includes terms involving the atomic density (n), electron back‐scattering factor (R) and electron escape depth (L). Many schemes have been proposed by various people for corrections of the R and L terms. However, up to now, there have been no systematic investigations of the correction accuracy of the proposed schemes. We have evaluated the correction accuracy, based on measured intensity data for AuCu alloys of different compositions. Comparison was made between the observed intensity ratio K (=Iunk/Istd) and the calculated intensity, ratio K′ (= C(nunk/nstd)(Runk/Rstd)(Lunk/Lstd)), where C and I represent the concentration and intensity, respectively. The superscripts ‘unk’ and ‘std’ denote that the parameters are for unknown and standard specimens, here the pure elements. If the correction works well, the error Er (= K′  K)/(K) will become smaller. Evaluations were carried out on three schemes for the R correction and on seven schemes for the L correction using the Au 239 eV, Au 2024 eV and Cu 920 eV transitions. The root mean square (RMS) of the calculated errors showed several per cent for the best case and 20–30% for the worst case. The RMS error varied a few per cent between schemes for the R correction but it varied ∼30% for the L correction. Copyright © 1990 John Wiley &amp; Sons Ltd.

• MULTIPHOTON IONIZATION OF XE AND KR ATOMS BY AN ARF EXCIMER LASER

K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   29 ( 8 ) L1509 - L1510  1990.08

View Summary

The dependence of ionization signals of Xe and Kr atoms on the laser intensity has been studied using an ArF excimer laser. For both atoms, we observe a slope of 2 in the log-log plot of the ionization signal versus laser intensity, and saturation of ionization at laser pulse energies higher than about 100 mJ (1.7×10&lt;SUP&gt;10&lt;/SUP&gt; W/cm&lt;SUP&gt;2&lt;/SUP&gt;). The ionization of Kr can be interpreted as a 2-photon-resonant, 3-photon (2+1) ionization.

• MULTIPHOTON IONIZATION OF XE AND KR ATOMS BY AN ARF EXCIMER LASER

K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   29 ( 8 ) L1509 - L1510  1990.08

View Summary

The dependence of ionization signals of Xe and Kr atoms on the laser intensity has been studied using an ArF excimer laser. For both atoms, we observe a slope of 2 in the $\log$-$\log$ plot of the ionization signal versus laser intensity, and saturation of ionization at laser pulse energies higher than about 100 mJ ($1.7\times 10^{10}$ W/cm2). The ionization of Kr can be interpreted as a 2-photon-resonant, 3-photon ($2+1$) ionization.

• A NEW ION COUNTING SYSTEM DEVISED FOR MASS-SELECTIVE DETECTION OF SPUTTERED NEUTRALS IN LASER SNMS

S ICHIMURA, K GOTO, K KOKUBUN, H SHIMIZU, S MATSUURA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   29 ( 7 ) L1209 - L1212  1990.07

View Summary

A new ion counting system was devised for time-of-flight mass detection in sputtered neutral mass spectrometry (SNMS), using a pulse laser for postionization. A microchannel plate (MCP) intensifier used as a detector was gated by a retarding grid in front of the MCP for particular masses. High peak-counting ability (exceeding 10&lt;SUP&gt;10&lt;/SUP&gt; counts per second) of the system for ionization with a laser pulse (20–30 ns) was maintained for mass-selective detection. The performance of the new counting system at a high count rate was analyzed, and the detection limit and the accuracy were discussed.

• A NEW ION COUNTING SYSTEM DEVISED FOR MASS-SELECTIVE DETECTION OF SPUTTERED NEUTRALS IN LASER SNMS

S ICHIMURA, K GOTO, K KOKUBUN, H SHIMIZU, S MATSUURA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   29 ( 7 ) L1209 - L1212  1990.07

View Summary

A new ion counting system was devised for time-of-flight mass detection in sputtered neutral mass spectrometry (SNMS), using a pulse laser for postionization. A microchannel plate (MCP) intensifier used as a detector was gated by a retarding grid in front of the MCP for particular masses. High peak-counting ability (exceeding $10^{10}$ counts per second) of the system for ionization with a laser pulse (20–30 ns) was maintained for mass-selective detection. The performance of the new counting system at a high count rate was analyzed, and the detection limit and the accuracy were discussed.

• NONRESONANT MULTIPHOTON IONIZATION OF HE AND NE ATOMS

K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   29 ( 4 ) L673 - L674  1990.04

View Summary

The nonresonant multiphoton ionization of high-ionization-potential atoms, He and Ne, was successfully observed using a commercial high-power ArF excimer laser. The experimental results are presented.

• 一村信吾, 清水肇

ぶんせき   ( 4 ) 266 - 274  1990.04

• NONRESONANT MULTIPHOTON IONIZATION OF HE AND NE ATOMS

K KOKUBUN, S ICHIMURA, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   29 ( 4 ) L673 - L674  1990.04

View Summary

The nonresonant multiphoton ionization of high-ionization-potential atoms, He and Ne, was successfully observed using a commercial high-power ArF excimer laser. The experimental results are presented.

• S. Ichimura, K. Goto, K. Kokubun, H. Shimizu, H. Hashizume

Review of Scientific Instruments   61 ( 4 ) 1192 - 1195  1990

View Summary

A new counting system for charged particles, which is suitable for the counting of pulse trains arriving in a short time, was constructed. The system is composed of a microchannel-plate intensifier, a CCD camera, a frame buffer, a particle counter, and a personal computer. Ion (or electron) pulses incident on the microchannel plate are amplified and then converted to photoradiating spots on a fluorescent screen. The image of the bright spots on the screen is taken by the camera and stored in the frame buffer. The computer processes the stored data and counts the number of bright spots. The performance of the system was examined by applying it to the detection of ions generated by a pulse laser. More than 300 photoions generated by one laser pulse (pulse width: 30 ns) were successfully counted, indicating that the peak counting rate of the system exceeds 1010 cps.

• H. Nonaka, S. Ichimura, K. Arai, C. Le Gressus

Surface and Interface Analysis   16 ( 1-12 ) 435 - 439  1990

View Summary

Damageless conditions in AES measurement were examined carefully on both thermally oxidized and photochemical vapour deposited amorphous SiO2 films as a function of dose rate and total dose. The lower dose rate resulted in the formation of a higher density of oxygen‐deficient defects under the constant total dose condition. Among the films examined, it was found that F‐doped films prepared by photochemical vapour deposition best resisted electron damage. The results are discussed using the model of defect generation consisting of a cascade process, bond breaking and diffusion of oxygen. Copyright © 1990 John Wiley &amp
Sons Ltd.

• K. Yoshihara, R. Shimizu, T. Homma, H. Tokutaka, K. Goto, D. Fujita, A. Kurokawa, S. Ichimura, M. Kurahashi, M. Kudo, Y. Hashiguchi, T. Suzuki, T. Ohmura, F. Soeda, K. Tanaka, A. Tanaka, T. Sekine, Y. Shiokawa, T. Hayashi

Surface and Interface Analysis   16 ( 1-12 ) 140 - 143  1990

View Summary

The Japanese VAMAS‐SCA working group is composed of 19 institutes. Three kind of AuCu alloys (Au 75 at.‐%–Cu 25 at.‐%, Au 50 at.‐%–Cu 50 at.‐%, Au 25 at.‐%–Cu 75 at.‐%) were prepared, and these specimens, pure Au and pure Cu were distributed to the members of the VAMAS‐SCA working group. The surface concentrations of these alloys were calculated from the Auger peak amplitudes in two ways. One method used the published relative sensitivity factors, and the other used pure Au and Pure Cu as the standard materials. The mean values of the surface concentrations calculated with the published relative sensitivity factors were almost the same as those calculated with the standard materials. This means that the published relative sensitivity factors are reliable to some extent. The error of the surface concentration calculated with pure Au and pure Cu as the standard materials lay between about 3% and 10%, and that with the relative sensitivity factors lay between about 7% and 20%. The calculated surface concentrations of Au were larger than the bulk concentrations of Au when the matrix effect was neglected. Copyright © 1990 John Wiley &amp
Sons Ltd.

• Kiyohide Kokubun, Shingo Ichimura, Hiroko Hashizume, Hazime Shimizu, Yoshiro Oowadano, Yuji Matsumoto, Kazuhiro Endo

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films   8 ( 4 ) 3310 - 3313  1990

View Summary

For the purpose of applying the laser-ionization method to measuring gas pressure, the dependence of the ionization output signals of rare gases on the gas pressure and the laser intensity were studied using XeCl, KrF, and ArF excimer lasers. The proportional relation between the ionization signal and the gas pressure was experimentally verified to below 10 8 Torr. In the case of Kr gas, the dependence of the ionization signal on the laser intensity was in agreement with the theory of nonresonant multiphoton ionization, and saturation of ionization in the case of Xe was observed. © 1990, American Vacuum Society. All rights reserved.

• ICHIMURA Shingo, KOKUBUN Kiyohide, SHIMIZU Hazime

Shinku   33 ( 1 ) 15 - 20  1990

View Summary

A new ion counting system useful in pressure measurement with laser was constructed. The system is composed of a microchannel-plate intensifier, a CCD camera, a frame buffer, a particle counter, and a personal computer. By applying it to detection of acetone ions ionized by an excimer laser pulse, it was confirmed that the system has i) a high peak counting rate (exceeding 1010 cps), ii) linear response to the number of incident ions, and iii) higher accuracy than conventional analog detection system. The detection limit in the pressure measurement by laser with the present system is also discussed, and the measurement in the pressure range between 10-10 Pa and 100 Pa is projected.

• Kiyohide Kokubun, Shingo Ichimura, Hazime Shimizu

Shinku   33 ( 1 ) 7 - 14  1990

View Summary

For the purpose of applying the laser-ionization method to measuring gas pressure, particularly in the range of UHV and XHV, the laser-ionization characteristics for various kinds of gases have been studied using XeCl, KrF and ArF ex-cimer lasers. The proportional relation between the ionization signal and the gas pressure was experimentally verified to 1 × 10-8 Torr (1.3 × 10-6 Pa). In the case of rare gases and O2 gas, the dependence of the ionization signal on the laser intensity was in agreement with the theory of nonresonant multiphoton ionization. Saturation of ionization was observed in the case of Xe. © 1990, The Vacuum Society of Japan. All rights reserved.

• ICHIMURA Shingo

Hyomen Kagaku   11 ( 10 ) 604 - 611  1990

• DEPENDENCE OF THE NONRESONANT LASER IONIZATION OF RARE-GASES ON LASER WAVELENGTH

K KOKUBUN, S ICHIMURA, H HASHIZUME, H SHIMIZU, Y OOWADANO, Y MATSUMOTO, K ENDO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   28 ( 12 ) L2271 - L2272  1989.12

View Summary

The nonresonant multiphoton ionization of rare gases has been studied by means of XeCl, KrF and ArF excimer lasers. In the course of this study, it was observed that in the cases of the XeCl and KrF lasers, the ionization intensities of Xe gas were stronger than those of Kr gas, but in the case of the ArF laser, the former was weaker than the latter. This result is interpreted as an effect of laser wavelength.

• DEPENDENCE OF THE NONRESONANT LASER IONIZATION OF RARE-GASES ON LASER WAVELENGTH

K KOKUBUN, S ICHIMURA, H HASHIZUME, H SHIMIZU, Y OOWADANO, Y MATSUMOTO, K ENDO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   28 ( 12 ) L2271 - L2272  1989.12

View Summary

The nonresonant multiphoton ionization of rare gases has been studied by means of XeCl, KrF and ArF excimer lasers. In the course of this study, it was observed that in the cases of the XeCl and KrF lasers, the ionization intensities of Xe gas were stronger than those of Kr gas, but in the case of the ArF laser, the former was weaker than the latter. This result is interpreted as an effect of laser wavelength.

• DETECTION OF SPUTTERED PARTICLES BY MEANS OF NONRESONANT MULTIPHOTON SPECTROMETRY

H SHIMIZU, H HASHIZUME, S ICHIMURA

PROCEEDINGS OF THE 7TH SYMPOSIUM ON ION BEAM TECHNOLOGY     113 - 116  1989  [Refereed]

• S. Ichimura, H. E. Bauer, H. Seiler, S. Hofmann

Surface and Interface Analysis   14   250 - 256  1989.01

View Summary

Practical methods are investigated to reduce the charging which is often observed during AES analysis of insulating samples with keV electrons. It is shown that the negative charge caused by electron beams with keV energy can be either avoided or considerably reduced by the use of an additional electron beam or by the supply of low‐energy (500 eV) positive ions. It is also reported and discussed that the state of reduced or vanishing charging obtained by both methods can be maintained for long periods of time. Copyright © 1989 John Wiley &amp; Sons Ltd.

• S ICHIMURA, ZJ DING, R SHIMIZU

SURFACE AND INTERFACE ANALYSIS   12 ( 1-12 ) 161 - 161  1988.07

View Summary

The intensity of the measured spectrum, especially the Auger spectrum, is strongly affected by the contribution of backscattered electrons with high energy, since those energetic electrons can also excite Auger electrons at the surface. The aim of the present paper is to describe briefly how the energy distribution of backscattered electrons can be estimated and how the result can be applied for the quantitative analysis by electron spectroscopies, especially by AES.

• DETECTION OF SPUTTERED NEUTRAL ATOMS BY NONRESONANT MULTIPHOTON IONIZATION

H SHIMIZU, H HASHIZUME, S ICHIMURA, K KOKUBUN

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   27 ( 4 ) L502 - L505  1988.04

View Summary

A nonresonant multiphoton ionization method was applied for the detection of sputtered neutrals using a time-of-flight mass spectrometer. The preliminary results for Cu, Ni and Cu–Ni alloy samples are reported from the viewpoint of a semiquantitative surface analysis. Photoions from pure elements were a reflection of their sputtering yield ratios. The estimated composition of an alloy during sputtering at room temperature is almost the same as that of bulk. On the other hand, anomalous copper-enriched flux was detected at 800 K, and the result was explained by the enhanced segregation and diffusion of copper through the ion-damaged surface layer.

• DETECTION OF SPUTTERED NEUTRAL ATOMS BY NONRESONANT MULTIPHOTON IONIZATION

H SHIMIZU, H HASHIZUME, S ICHIMURA, K KOKUBUN

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   27 ( 4 ) L502 - L505  1988.04

View Summary

A nonresonant multiphoton ionization method was applied for the detection of sputtered neutrals using a time-of-flight mass spectrometer. The preliminary results for Cu, Ni and Cu–Ni alloy samples are reported from the viewpoint of a semiquantitative surface analysis. Photoions from pure elements were a reflection of their sputtering yield ratios. The estimated composition of an alloy during sputtering at room temperature is almost the same as that of bulk. On the other hand, anomalous copper-enriched flux was detected at 800 K, and the result was explained by the enhanced segregation and diffusion of copper through the ion-damaged surface layer.

• S ICHIMURA, T KOSHIKAWA, T SEKINE, K GOTO, H SHIMIZU

SURFACE AND INTERFACE ANALYSIS   11 ( 1-2 ) 94 - 102  1988.01

View Summary

The possibility of quantitative AES analysis using the whole EN(E) spectrum was examined for AuCu alloy samples. The EN(E) spectrum was measured under φ = 0° (normal) incidence of 10 keV electrons for the Au–44 at% Cu sample, and under φ = 0°, 30°, and 45° incidence of 10 keV primary electrons for the Au–20 at% Cu sample. Those spectra were compared with spectra which were obtained by linear combination of pure Au and Cu spectra measured under the same experimental conditions. Both measured and synthesized spectra coincided very well in the energy region lower than 1000 eV, except the region of slow secondary electrons. The results indicate that energy distribution of backscattered electrons of the AuCu alloy can be estimated well by linear combinations of pure sample spectra. They also indicate that, by comparison of the shape of the measured EN(E) spectrum with the synthesized one, the surface composition of the AuCu alloy sample can be estimated with reasonable accuracy (several % error). Copyright © 1988 John Wiley &amp; Sons Ltd.

• S. Ichimura, Ding Ze‐Jung, R. Shimizu

Surface and Interface Analysis   12 ( 2 ) 161 - 161  1988

• S. Ichimura, Ding Ze‐Jun, R. Shimizu

Surface and Interface Analysis   13 ( 2-3 ) 149 - 159  1988

View Summary

The simulation of electron/solid interactions is discussed, with emphasis on its applicability to the matrix correction in quantitative analysis by AES, and to its potential use in background substraction in AES. The Monte Carlo calculation models are first explained, which have been improved to allow the estimation of (i) back‐scattering correction factors, and (ii) energy profiles of back‐scattered electrons in the high‐energy region (i.e. elastically‐scattered electrons and the characteristic loss structures) and the slow secondary region. For this purpose, a dielectric approach is used for the treatment of the electron inelastic scattering in the solid. Then, the models are applied to samples with bi‐layer structures, and the change of Si Auger signals observed during sputter‐etching of a sample consisting of a Si thin film (7000 Å) on a W substrate is well explained. Changes in the energy distributions of back‐scattered electrons during the formation of very thin (5 to 100 Å) Cu films on a Si substrate are also estimated by the Monte Carlo calculation, together with the shapes of the elastic peak and the characteristic loss peaks. Copyright © 1988 John Wiley &amp
Sons Ltd.

• K. Yoshihara, R. Shimizu, T. Homma, H. Tokutaka, K. Goto, M. Uemura, D. Fujita, A. Kurokawa, S. Ichimura, C. Oshima, M. Kurahashi, M. Kudo, Y. Hashiguchi, Y. Fukuda, T. Suzuki, T. Ohmura, F. Soeda, K. Tanaka, A. Tanaka, T. Sekine, Y. Shiokawa, T. Hayashi

Surface and Interface Analysis   12 ( 2 ) 125 - 130  1988

View Summary

The Japanese VAMAS‐SCA working group is composed of 19 institutes. Three kinds of Au‐Cu alloys (Au25 at%‐Cu75 at%, Au50 at%‐Cu50 at%, Au75 at%‐Cu25 at%) were prepared, and these specimens were distributed to the members of Japanese VAMAS‐SCA working group and Auger peak amplitude ratios were measured to clarify the correlation factor of different types of spectrometers. The comparison was carried out by using the relative sensitivity factor for Au and Cu. The relative sensitivity factor for lower energy varied from spectrometer to spectrometer, but that for higher energy did not vary so much. Therefore, to carry out the inter‐laboratory comparison of the data, the transfer of the data of peak amplitude at higher energy should be recommended. Copyright © 1988 John Wiley &amp
Sons Ltd.

• Hidehiko Nonaka, Kazuo Arai, Yoshiyuki Fujino, Shingo Ichimura

Journal of Applied Physics   64 ( 8 ) 4168 - 4174  1988

View Summary

Amorphous silicon dioxide films were deposited from oxygen, disilane (Si2H6), and perfluorosilanes (Si2F6 or SiF4) by photochemical vapor deposition using a deuterium lamp at a substrate temperature of as low as 200 °C. It was found that by mixing Si2F6, defects such as H and OH in the films were effectively removed with an enhancement in the growth rate and a slight doping of fluorine into the films, while SiF4 had no effect except a little doping of fluorine. The generation and extinction of defects including H, OH, and SiSi were investigated quantitatively by measuring infrared spectra and vacuum ultraviolet absorptions at the optical band edge. The model on the deposition process was proposed that photodissociated F-containing radicals eliminate H and activate the growing surface, resulting in enhancing the deposition rate.

• Makoto Kato, Akinori Mogami, Motohiro Naito, Shingo Ichimura, Hazime Shimizu

Review of Scientific Instruments   59 ( 9 ) 1947 - 1950  1988

View Summary

Mass resolution of a time-of-flight mass spectrometer with a two-stage electrostatic reflector is calculated for secondary neutral mass spectrometry. The instrument parameters are optimized for energy and space focusing: correcting the flight time difference due to the energy width ΔE of sputtered particles and the spatial width Δs of an ionizing laser beam. The effect of Δs can be compensated by applying an acceleration field to the ionizing region, and the maximum resolution becomes about 1000 for ΔE = 10 eV and Δs = 1.0 mm.

• SYNERGISTIC ENHANCEMENT OF DIRECT SYNCHROTRON RADIATION ETCHING OF A RESIST BY A LOW-ENERGY OXYGEN BEAM

H MURAKAMI, S ICHIMURA, H SHIMIZU, KUDO, I, N ATODA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   26 ( 11 ) L1774 - L1776  1987.11

View Summary

The effect of the simultaneous irradiation of a low-energy oxygen ion beam with synchrotron radiation (SR) was investigated. The purpose was the enhancement of the direct resist etching by SR. Although the removal by sputtering of the resist was observed due to the wide energy width of the ion beam used, it was confirmed that the net SR etching, which was estimated after subtraction of the sputtering contribution, increased about two times. Possibilities for the enhancement of this &quot;synergistic effect&quot; induced by low-energy ion beam bombardment to improve the direct SR etching and make it more practical are also discussed.

• SYNERGISTIC ENHANCEMENT OF DIRECT SYNCHROTRON RADIATION ETCHING OF A RESIST BY A LOW-ENERGY OXYGEN BEAM

H MURAKAMI, S ICHIMURA, H SHIMIZU, KUDO, I, N ATODA

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   26 ( 11 ) L1774 - L1776  1987.11

View Summary

The effect of the simultaneous irradiation of a low-energy oxygen ion beam with synchrotron radiation (SR) was investigated. The purpose was the enhancement of the direct resist etching by SR. Although the removal by sputtering of the resist was observed due to the wide energy width of the ion beam used, it was confirmed that the net SR etching, which was estimated after subtraction of the sputtering contribution, increased about two times. Possibilities for the enhancement of this &quot;synergistic effect&quot; induced by low-energy ion beam bombardment to improve the direct SR etching and make it more practical are also discussed.

• PRELIMINARY-RESULTS OF VACUUM PRESSURE MEASUREMENT BY LASER IONIZATION METHOD

S ICHIMURA, K KOKUBUN, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   26 ( 5 ) L573 - L575  1987.05

View Summary

The possibility of vacuum pressure measurement by ionizing gaseous atoms or molecules with laser radiation was studied. Xe ions were successfully detected after irradiation by a focused Xe–Cl excimer laser, indicating that non-resonant 4 photon ionization was realized with the present system. It was confirmed that Xe signal intensity, as measured by a quadrapole mass analyzer, changed in proportion to Xe gas pressure from 10&lt;SUP&gt;−5&lt;/SUP&gt; Torr to 10&lt;SUP&gt;−9&lt;/SUP&gt; Torr. Xe isotopes were also measured and the results correlated well with their natural abundance.

• PRELIMINARY-RESULTS OF VACUUM PRESSURE MEASUREMENT BY LASER IONIZATION METHOD

S ICHIMURA, K KOKUBUN, H SHIMIZU

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   26 ( 5 ) L573 - L575  1987.05

View Summary

The possibility of vacuum pressure measurement by ionizing gaseous atoms or molecules with laser radiation was studied. Xe ions were successfully detected after irradiation by a focused Xe–Cl excimer laser, indicating that non-resonant 4 photon ionization was realized with the present system. It was confirmed that Xe signal intensity, as measured by a quadrapole mass analyzer, changed in proportion to Xe gas pressure from $10^{-5}$ Torr to $10^{-9}$ Torr. Xe isotopes were also measured and the results correlated well with their natural abundance.

• H SHIMIZU, S ICHIMURA, H MURAKAMI, H AGARI

JOURNAL OF NUCLEAR MATERIALS   145   408 - 411  1987.02

View Summary

Surface ion damage was studied for Cu/Ni, Au/Cu, Ag/Cu, Co/Ni, and Fe/Ni alloys during noble gas ion bombardment at elevated temperatures. Tests were also made for a coarse-grained Cu/Ni alloy at liquid nitrogen temperature. Results related to the effect of surface segregation on (a) the angular distribution of the sputtered atoms, and (b) the grain boundary erosion are presented. It was found that the segregated atoms have a tendency to be sputtered preferentially in the direction of the target surface for the case of Cu/Ni, and Co/Ni alloy at elevated temperatures. Such a tendency was observed for the sputtering of Cu/Ni alloy even at 100 K. However, it was not observed for Au/Cu, Ag/Cu, although the segregation phenomena were drastically observed. After sputtering of the Cu/Ni alloys at 873 K, the grain boundaries were no longer straight and some had developed zigzag shapes 2-3 μm in width. The cross section of the specimen showed the existence of large voids of 20-30 μm in depth and 3-5 μm in width just beneath the eroded grain boundaries, presumably due to the ion induced Kirkendall effect (IKE) . © 1987.

• Ding Ze‐jun, Ryuichi Shimizu, Shingo Ichimura

Surface and Interface Analysis   10 ( 5 ) 253 - 258  1987

View Summary

The backscattering factor R, which corrects matrix effects in quantitative AES analysis, was obtained from Monte Carlo calculations for the AuCu alloy system being proposed as test standard samples for quantitative surface chemical analysis. The Monte Carlo algorithm is based on the combined use of the Gryzinski's excitation function with the Bethe's stopping power for inelastic scattering and elastic scattering cross section obtained by partial wave expansion method. The calculation of R for 5 keV and 10 keV electrons at angles of incidence 0° and 45° lead to the functional representation R(Z, U) = A(Z)UB(Z) + C(Z), where Z is the mean atomic number of the sample and U the ratio of the primary energy to the binding energy. This representation describes the calculated R values within the maximum error 2%. Copyright © 1987 John Wiley &amp
Sons Ltd.

• SHIMIZU Hazime, ICHIMURA Shingo

OYOBUTURI   55 ( 4 ) 384 - 388  1986

• H TANINO, K HOH, M HIRATA, N ATODA, S ICHIMURA

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B   3 ( 1 ) 232 - 236  1985

View Summary

Novel methods are proposed to enlarge the vertical (normal to the plane of electron orbit) width of the exposed area in synchrotron radiation (SR) lithography. They are the shaping of the cross section of the SR beam by a fixed toroidal mirror with specified parameters and the superposition of the reflected SR beams from fixed planar mirrors onto the upper and lower peripheries of the straight beam. An experimental verification is presented, and merits and demerits of these methods are compared with those of other methods.

• S ICHIMURA, H SHIMIZU, H MURAKAMI, Y ISHIDA

JOURNAL OF NUCLEAR MATERIALS   128 ( DEC ) 601 - 604  1984

View Summary

The angular distribution of atoms sputtered from binary alloys (Cu/Ni, Co/Ni, and Fe/Ni) were investigated in relation to the surface segregation phenomenon of one component of the alloys. For the Cu/Ni alloy which has a tendency of strong Cu segregation at the alloy surface, the preferred Ni ejection was observed in the direction of target normal under the sputtering at both RT and 300°C. The preferred Co ejection in target normal directions was clearly discerned only at 300°C for the sputtering of the Co/Ni alloy, while no distinct preferred ejection of one component was observed for the Fe/Ni alloy. © 1984.

• ICHIMURA Shingo, SHIMIZU Hazime, HIRATA Masahiro

Shinku   27 ( 4 ) 267 - 279  1984

• Lithography Experiments using Synchrotron Radiation from ETL Storage Ring

Hoh Koichiro, Hirata Masahiro, Atoda Nobufumi, Tanino Hiroshi, Ichimura Shingo, Onuki Hideo

Jpn J Appl Phys   22 ( 4 ) 765 - 765  1983.04

• S ICHIMURA, M HIRATA, H TANINO, N ATODA, M ONO, K HOH

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B   1 ( 4 ) 1076 - 1079  1983

View Summary

Direct engraving of mask patterns in a resist film was tried by exposing with synchrotron radiation. Using a stencil mask made of a Si//3N//4 substrate, submicron structures could be successfully replicated. Fundamental aspects of resist decomposition by synchrotron radiation were also investigated by mass and electron spectroscopy.

• N ATODA, H KAWAKATSU, H TANINO, S ICHIMURA, M HIRATA, K HOH

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B   1 ( 4 ) 1267 - 1270  1983

View Summary

With synchrotron radiation from the storage ring ETL-TERAS, the influence of Fresnel diffraction on replicated patterns was investigated. Spatial intensity distributions due to the diffraction were calculated with Fresnel integrals and compared with replicated patterns. Pattern degradation due to the diffraction depends on a parameter U//0 equals W/(G//p lambda /2)** one-half , where W is the pattern width, G//p the mask-to-wafer distance, and lambda the wavelength. From the calculation and the experiments it is concluded that the value of U//0 is needed to be larger than about three for a satisfactory pattern replication. Work with an experimental stencil mask with patterns of submicron dimensions is also described briefly.

• S ICHIMURA, R SHIMIZU, JP LANGERON

SURFACE SCIENCE   124 ( 2-3 ) L49 - L54  1983

View Summary

Backscattering factors for quantitative Auger analysis which were obtained by Monte Carlo calculations were analytically represented by using simple functions. This should enable the backscattering correction procedure in quantitative Auger analysis to be of more practical use. © 1983.

• R SHIMIZU, S ICHIMURA

SURFACE SCIENCE   133 ( 1 ) 250 - 266  1983

View Summary

A Monte Carlo simulation of the scattering processes of kV electrons penetrating into aluminum was performed. The simulation is based on the use of different types of differential cross-sections for individual elastic and inelastic scattering: (i) Elastic scattering; the differential cross-sections derived by partial wave expansion method. (ii) Inelastic scattering; Gryzinski&#039;s excitation function for inner-shell electron excitation, Streitwolfs excitation function for conduction electron excitation, and Quinn&#039;s mean free path for plasmon excitation. For verification the energy loss spectra obtained from the Monte Carlo calculations were then compared with experiment done with commercial type Auger microprobes, JAMP-3, for angle of incidence 45° and JAMP-10 for normal incidence at primary electron energies of 1.5 and 3.0 keV, respectively. The results show satisfactory agreement between theory and experiment. © 1983.

• K OBORI, R SHIMIZU, T OURA, S ICHIMURA

JOURNAL OF APPLIED PHYSICS   54 ( 1 ) 150 - 154  1983

View Summary

The applicability of the Monte Carlo calculation technique for quantitative analysis of particulate samples with an electron probe microanalyzer was verified through comparison between theoretical and experimental results for an NBS K-411 series of glass particulates. Good agreement between theory and experiment suggests that the Monte Carlo calculation technique will be a useful tool for performing quantitative electron probe microanalysis of individual particulate samples.

• LARGE AREA EXPOSURE IN SYNCHROTRON RADIATION LITHOGRAPHY UTILIZING THE STEERING OF THE ELECTRON-BEAM IN THE STORAGE RING

H TANINO, K HOH, M HIRATA, S ICHIMURA, N ATODA, T TOMIMASU, T NOGUCHI, S SUGIYAMA, T YAMAZAKI

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   22 ( 11 ) L677 - L679  1983

View Summary

It is demonstrated that the vertical (normal to the plane of electron orbit) width of exposed region in synchrotron radiation lithography can be expanded by a factor of more than three by steering the electron beam in the storage ring with a horizontal magnetic field, without losing intensity and homogeneity. The vertical distribution of the developed thickness in the resist and its vertical shift with the steering magnetic field are evaluated. The perturbation in the electron orbit is also estimated from the shifts of soft X-rays and visible illuminated regions.

• Lithography Experiments using Synchrotron Radiation from ETL Storage Ring

Hoh Koichiro, Hirata Masahiro, Atoda Nobufumi, Tanino Hiroshi, Ichimura Shingo, Onuki Hideo

Japanese Journal of Applied Physics   22 ( 4 ) 765 - 765  1983

• MASS-SPECTROSCOPIC AND ELECTRON-SPECTROSCOPIC OBSERVATION OF RESIST DECOMPOSITION BY SYNCHROTRON RADIATION

S ICHIMURA, M HIRATA, H TANINO, N ATODA, K HOH, M ONO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   22 ( 7 ) L406 - L408  1983

View Summary

Analytical techniques of mass- and electron-spectroscopy were applied to the observation of lithography by synchrotron radiation (SR). During the exposure of positive resist to SR, the tendency of side-chain components easily dissociating was shown by mass spectroscopy. &lt;I&gt;In-situ&lt;/I&gt; analysis with electron spectroscopy showed that the height of a peak appearing at low energy increased during the exposure when the power density of SR was high. This increase was closely related to the reduction in the film thickness by SR due to the dissociation of constituent molecules of the resist.

• MASS-SPECTROSCOPIC AND ELECTRON-SPECTROSCOPIC OBSERVATION OF RESIST DECOMPOSITION BY SYNCHROTRON RADIATION

S ICHIMURA, M HIRATA, H TANINO, N ATODA, K HOH, M ONO

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   22 ( 7 ) L406 - L408  1983

View Summary

Analytical techniques of mass- and electron-spectroscopy were applied to the observation of lithography by synchrotron radiation (SR). During the exposure of positive resist to SR, the tendency of side-chain components easily dissociating was shown by mass spectroscopy. In-situ analysis with electron spectroscopy showed that the height of a peak appearing at low energy increased during the exposure when the power density of SR was high. This increase was closely related to the reduction in the film thickness by SR due to the dissociation of constituent molecules of the resist.

• LARGE AREA EXPOSURE IN SYNCHROTRON RADIATION LITHOGRAPHY UTILIZING THE STEERING OF THE ELECTRON-BEAM IN THE STORAGE RING

H TANINO, K HOH, M HIRATA, S ICHIMURA, N ATODA, T TOMIMASU, T NOGUCHI, S SUGIYAMA, T YAMAZAKI

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   22 ( 11 ) L677 - L679  1983

View Summary

It is demonstrated that the vertical (normal to the plane of electron orbit) width of exposed region in synchrotron radiation lithography can be expanded by a factor of more than three by steering the electron beam in the storage ring with a horizontal magnetic field, without losing intensity and homogeneity. The vertical distribution of the developed thickness in the resist and its vertical shift with the steering magnetic field are evaluated. The perturbation in the electron orbit is also estimated from the shifts of soft X-rays and visible illuminated regions.

• S ICHIMURA, R SHIMIZU, T IKUTA

SURFACE SCIENCE   115 ( 2 ) 259 - 269  1982

View Summary

The validity and utility of the backscattering correction factors obtained from Monte Carlo calculations for quantitative analysis by Auger electron spectroscopy (AES) were examined through practical quantification of surface concentrations of binary alloys. Quantifications were attempted, first, to access the surface composition of a sputter-deposited NiPt layer, which is probably the most appropriate test-sample with known surface composition for surface analysis. The quantification by AES has led to the result that the surface composition of the layer agrees well with the bulk composition of the sputtered NiPt alloy, as expected. The composition of a sputtered AuCu alloy surface was, then, examined according to the same correction procedure as for the NiPt layer, leading to the confirmation that no preferential sputtering is observed for AuCu alloys by AES as Färber et al. reported. © 1982.

• ICHIMURA Shingo, SHIMIZU Ryuichi

Shinku   25 ( 10 ) 645 - 659  1982

• BACKSCATTERING FACTOR IN AU-CU ALLOYS FOR QUANTITATIVE-ANALYSIS BY SCANNING AUGER-ELECTRON MICROSCOPY

S ICHIMURA, R SHIMIZU, T IKUTA

SCANNING ELECTRON MICROSCOPY     231 - 236  1981  [Refereed]

• APPLICATION OF MONTE-CARLO TECHNIQUE TO QUANTITATIVE AUGER ANALYSIS - AN APPROACH FOR QUANTITATIVE CORRECTION OF ELECTRON BACKSCATTERING EFFECT

R SHIMIZU, S ICHIMURA

SCANNING ELECTRON MICROSCOPY     221 - 230  1981  [Refereed]

• S ICHIMURA, M ARATAMA, R SHIMIZU

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY   18 ( 1 ) 34 - 36  1981

View Summary

A Monte Carlo simulation approach was applied for an interpretation of quantitative analysis using AES. The theoretical calculation has revealed that the shape of the energy distributions of backscattered electrons hardly changes as concentration (x) of Al//xGa//1// minus //xAs changes from x equals 0 to 1 and this leads to the linearity observed by J. R. Arthur and J. J. LePore.

• S ICHIMURA, M SHIKATA, R SHIMIZU

SURFACE SCIENCE   108 ( 1 ) L393 - L398  1981

View Summary

Surface segregations of Cu and S in a CuNi (50wt%) alloy at elevated temperatures of ∼600°C were studied under scanning Auger electron microscope, JAMP-3. Scanning images of S, Cu and Ni Auger signals have revealed that the surface segregations of both Cu and S take place preferentially depending on grains and the contrasts in S and Cu Auger images are complementary. This leads to another confirmation of the previous work, namely, that the surface segregation of Cu is considerably suppressed by the existence of S at the outermost atom layer. © 1981.

• S ICHIMURA, R SHIMIZU

SURFACE SCIENCE   112 ( 3 ) 386 - 408  1981

View Summary

The electron backscattering effect which is important for the quantitative interpretation of &quot;matrix effects&quot; in AES is investigated by applying the Monte Carlo calculation technique. The present calculation model is based on the use of a precise elastic scattering cross-section obtained by the partial wave expansion method, as well as on the combined use of Gryzinski&#039;s excitation function and Bethe&#039;s stopping power for inelastic scattering. Systematic calculations of the backscattering factors were performed for over 25 materials including pure elements, compounds, and alloys, which have been widely used as standard materials for practical Auger analysis. The results should enable the accuracy of quantitative analysis by AES to be improved. © 1981.

• K GOTO, S ICHIMURA, R SHIMIZU

REVIEW OF SCIENTIFIC INSTRUMENTS   51 ( 1 ) 95 - 97  1980

View Summary

A digital integration technique based on the use of V/F and D/A converters accompanied by the digital scanning and the synchronous square-wave modulation has been introduced in the scanning Auger electron microscopy. This integrator allows us to perform integration in very high efficiency leading to high signal to noise ratio and to high spatial resolution of the Auger pictures.

• T OKUTANI, M SHIKATA, S ICHIMURA, R SHIMIZU

JOURNAL OF APPLIED PHYSICS   51 ( 5 ) 2884 - 2887  1980

View Summary

Angular distributions of sputtered Si atoms from polycrystalline Si targets were measured for Ar+ions of 3 and 10 keV, at angles of incidence of 0°(normal incidence) and 60°. The results were compared with the theoretical ones obtained from Monte Carlo calculations by Kang et al. Theory describes qualitatively the experimental results fairly well. Some discrepancy between the theoretical and experimental results was, however, found in the preferred ejection angles. The preferred ejection angle of the experimental results for 10 keV at angle of incidence of 60°agrees very well with that suggested by the universal curve of the correlation between the preferred ejection angle and sputtering yield, which has been proposed by Betz et al.

• S ICHIMURA, M ARATAMA, R SHIMIZU

JOURNAL OF APPLIED PHYSICS   51 ( 5 ) 2853 - 2860  1980

View Summary

A Monte Carlo calculation technique based on both the partial wave expansion method for elastic scattering and Krefting and Reimer&#039;s treatment for inelastic scattering was applied for quantitative study by Auger electron spectroscopy. The theory has described the experiment of energy and angular distributions of backscattered electrons with considerable success. Dependence of the Auger signal generation on primary electron energy was investigated with a scanning Auger electron microscope, and the result was compared with the theory for a number of elements of practical interest. Through this, we have found that the present Monte Carlo approach allows us to evaluate contributions of backscattered electrons to Auger signal generation leading to more comprehensive quantitative AES study.

• K. Goto, S. Ichimura, R. Shimizu

Review of Scientific Instruments   50   46 - 47  1979.12

View Summary

The modulation frequency on the cylindrical mirror analyzer of a scanning Auger microscope has been synchronized to the digital scanning system. This technique allows one to obtain an Auger image free from moiré patterns which arise from the beat between scanning and modulation frequencies, and permits operation at frequency settings which optimize use of the electronics in the detection system.

• S. Ichimura, R. Shimizu

Journal of Applied Physics   50   6020 - 6022  1979.12

View Summary

Electron beam damage to thin-film SiO2was observed with a scanning Auger electron microscope. After a certain degree of electron beam exposure, changes in both the surface topography and chemical composition were investigated. The result suggested that there is a close relationship between the beam damage and the dissipation of incident energy in thin-film SiO2.

• R. Shimizu, T. Shinike, S. Ichimura, S. Kawaii, T. Tanaka

J Vac Sci Technol   15   922 - 926  1978.01

View Summary

The performance of single-crystal LaB//6 cathode was examined by measuring the brightness and current stability under the same conditions as for the conventional W hairpin cathode. The LaB//6 cathode was mounted in Vogel-type electron gun assembly of an electron probe microanalyser JAX-3 specifically modified for this purpose. The result shows that the present LaB//6 cathode provides not only high brightness of 2 multiplied by 10**5 A/cm**2 str. at 20 kV, but also high-current stability better than 1 multiplied by 10** minus **3 Ah** minus **1 in standard operation without any specific aid for current stabilization. Thus an order of magnitude increase in both the brightness and service lifetime can easily be obtained provided that the vacuum of the system is adequate, namely better than 1 multiplied by 10** minus **5 Torr (1. 33 multiplied by 10** minus **3 Pa). This substantial improvement of the present single-crystal LaB//6 cathode over the conventional W hairpin was also confirmed in a practical way by use in a commercial-type scanning Auger electron microscope, JAMP III.

• R. Shimizu, M. Aratama, S. Ichimura, Y. Yamazaki, T. Ikuta

Applied Physics Letters   31   692 - 694  1977.12

View Summary

Spatial distributions of Auger signals generated in an aluminum target in scanning Auger electron microscopy were obtained by Monte Carlo calculations including secondary electron generation. In the low-energy region, the cross sections calculated by the partial wave expansion method were used instead of the screened Rutherford cross section to describe the elastic scattering process. The result suggests that secondary electrons of high energy are a significant source of Auger signals, particularly LVV-Auger electrons, in scanning Auger electron microscopy.

• An Application of Square Wave Modulation Technique to Scanning Auger Electron Microscopy

Goto Keisuke, Ichimura Shingo, Shimizu Ryuichi

Jpn J Appl Phys   16 ( 11 ) 2087 - 2088  1977.11

• An Application of Square Wave Modulation Technique to Scanning Auger Electron Microscopy

Goto Keisuke, Ichimura Shingo, Shimizu Ryuichi

Japanese Journal of Applied Physics   16 ( 11 ) 2087 - 2088  1977

### Books and Other Publications

• Spectroscopy for Material Research

Shingo Ichimura, Satoshi Hashimoto, Yoshitoki IIjima( Part： Joint editor)

2020.11 ISBN: 9784065207871

• ナノ粒子計測

一村, 信吾, 日本分析化学会( Part： Joint author, まえがき、第1章、2.4節、4.1.1項)

共立出版  2018.11 ISBN: 9784320044562

• Nanotechnology Standards/ Current Standardization activities of Measurement and Characterization for Industrial Applications

Shingo Ichimura, Hidehiko Nonaka( Part： Joint author, Chapter 6: Current Standardization activities of Measurement and Characterization for Industrial Applications)

Springer  2011

• オージェ電子分光法（表面分析技術選書)

一村信吾他( Part： Joint author, 第3章:定性と定量)

丸善株式会社  2001

• 超精密計測がひらく世界

一村信吾( Part： Joint author, 第9章:真空中の原子・分子を一つ一つ見て数える)

講談社  1998

• 超高真空

清水, 肇, 榎本, 祐嗣, 一村, 信吾( Part： Joint author, 第2章： 「雰囲気のコントロール」、「温度のコントロール」、「ビームの発生」、)

オーム社  1997.11 ISBN: 4274023605

• シンクロトロン放射光の基礎

一村信吾他( Part： Joint author, 3.3.4章： 極高真空発生・計測技術)

丸善株式会社  1996

• 固体表面分析

一村信吾他( Part： Joint author, 2.3章： オージェ電子分光法)

講談社サイエンティフィック  1995

• マイクロビームアナリシス-現状と展望-、

一村信吾他( Part： Joint author, 5.1章： レーザを用いたアトムカウンティングとSNMS)

日本学術振興会  1992

• 超高真空実験マニュアル

一村信吾他( Part： Joint author, 7.2章： 真空装置用光学材料と光源)

日刊工業新聞社  1991

### Misc

• Significance of standardization in an era of global competition - case example in nanotechnology-

ICHIMURA Shingo

Abstract of annual meeting of the Surface Science of Japan   33 ( 0 ) 85 - 85  2013

• 一村 信吾

標準化と品質管理   63 ( 5 ) 96 - 99  2010.05

• KAMEDA Naoto, NISHIGUCHI Tetsuya, MORIKAWA Yoshiki, KEKURA Mitsuru, USHIYAMA Tomoharu, NONAKA Hidehiko, ICHIMURA Shingo

Journal of the Vacuum Society of Japan   53 ( 3 ) 230 - 233  2010.03  [Refereed]

View Summary

&nbsp;&nbsp;SiO2 film was made on Si(100) by two-step film growth process at 100&deg;C to improve the interface properties. The first part of the process is the direct Si oxidation using UV-excited ozone (O(1D)), which is generated by the UV irradiation to high concentrated (>90%) ozone gas. In the second part, O(1D) and Hexamethyldisilazane chemical vopor deposition (CVD)(O(1D)-CVD) process is used. The SiO2 film thickness of the direct Si oxidation for 10 min. in the two-step SiO2 film was estimated to be about 3.2 nm from the etching rate in change a buffered HF solution. Interface trap density Dit of the two-step SiO2 film with direct Si oxidation of 10 min. is almost equal to that of Si direct oxidation film alone. This result indicates that two-step oxidation process can be applied for the practical fabrication.<br>

• Infrared Absorption of an Ozone Molecule: Application for Measuring Its Partial Pressure and Evaluating Molecular Dissociation

Nakamura Ken, Kameda Naoto, Nishiguchi Tetsuya, Nonaka Hidehiko, Ichimura Shingo

Abstract of annual meeting of the Surface Science of Japan   30 ( 0 ) 398 - 398  2010

• Cluster Ion Beam Source Using Vacuum Electrospray of Ionic Liquids for Secondary Ion Mass Spectrometry (SIMS)

Yukio Fujiwara, Naoaki Saito, Hidehiko Nonaka, Taisuke Nakanaga, Shingo Ichimura

7th International Symposium on Atomic Level Characterizations for New Materials and Devices '09     471 - 474  2009.12

Article, review, commentary, editorial, etc. (international conference proceedings)

• KAMEDA Naoto, NISHIGUCHI Tetsuya, MORIKAWA Yoshiki, KEKURA Mitsuru, NONAKA Hidehiko, ICHIMURA Shingo

Journal of the Vacuum Society of Japan   52 ( 4 ) 245 - 247  2009.04

View Summary

&nbsp;&nbsp;We have developed a high efficiency ozone killer for reduced pressure and high concentration ozone using ultra-violet (UV) light irradiation to ozone gas. The highly concentrated ozone gas (&sim;100%) of 30-110 Pa with a flow rate of 50 sccm&dagger; can be decomposed to the concentration as low as 5% by UV light (200 nm-300 nm, 15 mW/cm2) irradiation. However, the residual ozone gas concentration increases the supplied ozone flow rate, since ozone molecule must stay in the ozone killer to absorb a UV photon. The photo-type ozone killer can be practically applied to actual processes by optimizing the dimension of the killer for a given pressure and gas flow rate.<br>

• FUJIWARA Yukio, KONDOU Kouji, TERANISHI Yoshikazu, WATANABE Kouji, NONAKA Hidehiko, SAITO Naoaki, ITOH Hiroshi, FUJIMOTO Toshiyuki, KUROKAWA Akira, ICHIMURA Shingo, TOMITA Mitsuhiro

Journal of the Vacuum Society of Japan   52 ( 4 ) 231 - 236  2009.04

View Summary

&nbsp;&nbsp;A new ion source using massive molecules called metal cluster complexes has been developed. Metal cluster complexes are chemically-synthesized organometallic compounds, which have a wide range of chemical compositions with high molecular weight. The ion source is compact enough to be installed in commonly used secondary ion mass spectrometry (SIMS) systems. Using the ion source, sputtering characteristics of silicon bombarded with normally incident Ir4(CO)7+ ions were investigated. Experimental results showed that the sputtering yield at 10 keV was 36, which is higher than that with Ar+ ions by a factor of 24. In addition, SIMS analyses of boron-delta-doped silicon samples and organic films of poly(methyl methacrylate) (PMMA) were performed. Compared with conventional O2+ ion beams, Ir4(CO)7+ ion beams improved depth resolution by a factor of 2.5 at the same irradiation conditions; the highest depth resolution of 0.9 nm was obtained at 5 keV, 45&deg; with oxygen flooding of 1.3&times;10-4 Pa. Furthermore, experimental results confirmed that Ir4(CO)7+ ion beams significantly enhanced secondary ion intensity in high-mass region.<br>

• WATANABE Kouji, KONDOU Kouji, FUJIWARA Yukio, SAITO Naoaki, NONAKA Hidehiko, ICHIMURA Shingo

Journal of the Vacuum Society of Japan   52 ( 3 ) 117 - 120  2009.03

View Summary

&nbsp;&nbsp;A ruby capillary which is available as an industrial product for the wire bonding machines for the microelectronics has been adopted to focus ion beams passively for the first time. An Ar+ ion beam with a beam current density of 3&times;10-6 A&bull;cm-2 at an energy of 4 keV has been found to penetrate steadily the ruby capillary and the behavior of the beam through the capillary has been investigated in details. It has been also found that a large amount of secondary electrons are generated when the ion beam hits the capillary and a negative bias should be applied to the Faraday cup to measure the ion beam current through the capillary though the positive ion beam is to be measured.<br>

• KAMEDA Naoto, SAITO Shigeru, NISHIGUCHI Tetsuya, MORIKAWA Yoshiki, KAKURA Mitsuru, NONAKA Hidehiko, ICHIMURA Shingo

Journal of the Vacuum Society of Japan   51 ( 3 ) 228 - 231  2008.03

View Summary

&nbsp;&nbsp;We have oxidized Si wafer at lower than 200&deg;C using an electronically excited oxygen atom that is generated by the irradiation of UV light to low pressure highly concentrated ozone gas. We used high-pressure mercury lamp, as the light source because it has a strong emission between 210 nm and 300 nm by which ozone is effectively absorbed and photo-excited. SiO2 film formation with its thickness fluctuation of less than 0.2 nm within light-irradiated area has been easily achieved as long as the intensity of the light irradiated to low-pressure ozone is uniform within 10 percent. The SiO2 film thickness is 3.3-4.1 nm at 200&deg;C for 10 min on the 8&Prime;Si(100) wafer. By the sample rotation during oxidation process, we could oxidize the SiO2 film homogeneously on the 8&Prime; wafer.<br> &nbsp;&nbsp;This film can be applied to a buffer layer between deposited film and poly-Si substrate of the gate dielectric film of the low temperature poly-Si thin film transistor.<br>

• Hidehiko Nonaka, Shingo Ichimura, Ryoji Kosugi, Kenji Fukuda, Kazuo Arai

Journal of the Vacuum Society of Japan   51 ( 3 ) 221 - 223  2008

View Summary

The highly concentrated (almost 100 vol.%) ozone gas has been utilized to dry oxidation of SiC single crystal substrates by using a quartz furnace with local heating by a halogen heater. When the flow velocity of ozone was kept as high as 5 m·cm-1 or more, the strong oxidizing power of ozone enabled rapid oxidation of SiC at a considerably lower temperature than that for the oxidation in oxygen. The ozone oxidation also resulted in a lower interface state density in the device charactrization for the MOS structure probably because the ozone oxidation was effective in reducing carbon-related defects.

• Ken Nakamura, Hidehiko Nonaka, Naoto Kameda, Tetsuya Nishiguchi, Shingo Ichimura

Journal of the Vacuum Society of Japan   51 ( 3 ) 224 - 227  2008

View Summary

Fourier-Transformed Infrared absorption spectroscopy (FT-IR) was applied to analysis of initial photochemical reaction of ozone (O3) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature in the gas phase under the irradiation of an ultraviolet (UV) light, as the side reaction during the fabrication of a silicon oxide (SiO2) film by photo-assisted chemical vapor deposition (CVD). FT-IR spectrum indicated the photodissociation of O3 by the UV light, shown by the decreases in the intensity of peaks assigned to an O3 molecule in the spectrum. Under the confirmation of this photodissociation of an O3 molecule, while the UV light is known to induce no photochemical reaction of HMDS, FT-IR spectrum indicated the photochemical reaction of HMDS by its scission of Si-N-Si bond and formation of C = O bond and SiO2 in a mixture of O3 and HMDS gases, thus showing that direct reaction of photodissociated species from O3, possibly atomic oxygen, with HMDS.

• Naoto Kameda, Tetsuya Nishiguchi, Yoshiki Morikawa, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   50 ( 3 ) 208 - 210  2007

View Summary

We have grown SiO2 film on the polycrystalline Si layer using excited ozone gas, which is produced by ultra-violet light irradiation to ozone gas, and characterized the electric properties of the SiO2 film at the MIS capacitor configuration. Even at room temperature, the SiO2 of ∼8.5 nm thick can be grown in 60 min. on 1.5 × 1.5 cm2 poly-Si chips. The leakage current density across the SiO2 film was well fitted to the F-N tunnel current over 6 MV/cm and the breakdown occurred at above 12 MV/cm showing that the film properties satisfy the device quality. The oxidation rate of Si by the excited ozone gas did not show difference on between Si(100) and Si (111) wafers. These results indicate that excited ozone gas can form homogenous SiO2 film on the poly-silicon layer with grains with various silicon crystal orientations at the surfaces.

• Report on the 2nd Plenary Meeting of the ISO TC 229 (Nanotechnology)

ICHIMURA Shingo

Hyomen Kagaku   27 ( 11 ) 673 - 674  2006.11

• Aki Tosaka, Tetsuya Nishiguchi, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   49 ( 3 ) 123 - 125  2006

View Summary

Silicon oxidation process using UV-light excited ozone, i.e., ca. 100% ozone atmosphere irradiated by KrF excimer laser light (λ = 248 nm), is one of the most promising techniques to fabricate a high-quality SiO 2 film at low temperatures. To clarify the mechanism of the silicon oxidation and to optimize the conditions of oxidation, we have done a time-resolved measurement of ozone density. The result shows that there are three stages of ozone density change. The calculated ozone density based on a reaction model fits the observed density at the first stage.

• Y. Teranishi, K. Kondou, Y. Fujiwara, H. Nonaka, K. Yamamoto, T. Fujimoto, S. Ichimura

Digest of Papers - Microprocesses and Nanotechnology 2005: 2005 International Microprocesses and Nanotechnology Conference   2005   146 - 147  2005.12

• 藤本俊幸, 溝田武志, 野中秀彦, 黒河明, 一村信吾

J Surf Anal   12 ( 1 ) 2 - 8  2005.03

• Atsushi Suzuki, Akira Kurokawa, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   48 ( 3 ) 139 - 141  2005

View Summary

Taking into account the utilization of partial pressure measurement under various temperatures and humidity, their influence on this measurement with a capacitance manometer and a quartz friction pressure gauge (Q-gauge) is studied. With increasing humidity, a Qgauge pressure reading, calibrated by air gas, decreases as well as when the hydrogen leakage is detected. To avoid this error by humidity for the hydrogen sensing, we tried to compensate influence of humidity using a humidity coefficient which is calculated from the humidity dependence of the Q-gauge pressure reading at constant temperature, and suppressed to one-fifth of the fluctuation of the Qgauge pressure reading background due to humidity change. Regarding to influence of temperature on the Q-gauge pressure reading, it is calibrated by the temperature dependence at low humidity. Finally, influences of temperature and humidity on the hydrogen sensing can be reduced by the calculation below the reading by 0.6 at.% of hydrogen gas.

• Naoaki Saito, Masataka Ohkubo, Masahiro Ukibe, Akihiro Kushino, Akira Kurokawa, Takeshi Mizota, Tomoya Kinumi, Yasushi Shigeri, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   48 ( 3 ) 211 - 213  2005

View Summary

We have started the development of a new time-of-flight mass spectrometer equipped with Nb/Al superconducting-tunnel-junction detectors. Metal cluster ions were employed to investigate the properties of the superconducting ion detectors. In addition to mass spectroscopy with wide mass range, we have performed impact energy measurement, which enables charge-state discrimination.

• Aki Tosaka, Tetsuya Nishiguchi, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   48 ( 5 ) 309 - 312  2005

View Summary

UV light-exited ozone has been applied for rapid low-temperature oxidation of silicon in a wafer-transfer type chamber. Oxidation was made in almost 100% ozone atmosphere with KrF excimer laser (248 nm) which enables the effective supply of O (1D) atoms to the processed surface. In this system, SiO2 film with a thickness of more than 3.5 nm is achieved even as low as 200°C. Uniform 2.9 nm film formation over 5-inch wafer with a thickness fluctuation of 0.1 nm was also obtained when KrF laser irradiation area was enlarged by a cylindrical concave lens. Current-voltage measurement has been employed to characterize SiO2 films and it is confirmed that the catastrophic breakdown field strength was 13 MV/cm. Processing pressure dependence of density of O(1D) atoms which contributing to the oxidation was estimated. Experimental result that the thickness of SiO 2 film increases by decreasing the processing pressure agrees with our estimated result at the pressure range between 340 Pa and 820 Pa.

• Tetsuya Nishiguchi, Takeshi Noyori, Yoshiki Morikawa, Mitsuru Kekura, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   48 ( 5 ) 313 - 316  2005

View Summary

We have deposited silicon dioxide (SiO2) film at temperatures lower than 300°C by supplying Hexamethyldisilazane (HMDS) and 03 gas with nearly 100% concentration alternately and cyclically. The 100%-03 gas has confirmed to be reactive enough to decompose the HMDS gas into CO2, H2O as well as the precursors leading to SiO2 deposition such as SiO even at room temperature. The physical characterization of thus deposited film gives a refractive index of 1.45-1.51, no Si-CH3 bond content and a process-dependent Si-OH content in the film. The film deposited by 10 Pa-HMDS and 2700 Pa-100%-O3 alternate supply has had a minimum Si-OH content and a good insulating property, i.e., leakage current density of lower than 10-7 A/cm2 at the electric field application of 4 MV/cm. This property is better than the film deposited by plasma-enhanced chemical-vapor-deposition using SiH4/O2 gas at 350°C.

• Atsushi Suzuki, Akira Kurokawa, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   48 ( 7 ) 448 - 450  2005

View Summary

For safety hydrogen sensing, the pressure measurement with a capacitance manometer and a quartz friction pressure gauge (Q-gauge) were investigated. Q-gauge pressure reading decreases when hydrogen gas is introduced into air supplied from atmosphere without any change of pressure measured by a capacitance manometer. This result indicates that the present pressure measurement using two pressure gauges is possible to detect the hydrogen leakage into air. In addition, a decrease of Q-gauge pressure reading correlates with a flow rate of the hydrogen gas, and increases with hydrogen concentration in air. Then it was shown that the low detection limit of hydrogen concentration is below 1%. Response time for hydrogen introduction is faster than 30 seconds, which meets the requirements for the hydrogen gas leak sensor. As above, the present safe pressure measurement using a capacitance manometer and a Q-gauge is satisfactorily useful for the hydrogen gas leak sensing.

• Now is Time to Challenge the Development of New Scientific Instruments

ICHIMURA Shingo

Hyomen Kagaku   25 ( 4 ) 191 - 191  2004.04

• 一村 信吾

マテリアルステージ   4 ( 1 ) 91 - 99  2004.04

• 一村信吾, 野中秀彦, 黒河明, 西口哲也

ケミカルエンジニヤリング   49 ( 2 ) 137 - 143  2004.02

• Akira Kurokawa, Sonoko Tsukahara, Takichi Kobayashi, Hisao Hojyo, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   47 ( 3 ) 151 - 154  2004

View Summary

A concentration measuring method for a binary gas system, which was based on the viscosity measurement, was investigated. The method utilizes two types of pressure gauges, a capacitance manometer which depends just on pressure and a quartz friction pressure gauge which depends on both viscosity and pressure of a binary gas. The concentration of the binary gas can be estimated from the viscosity because the viscosity is given as a function of concentration of the binary gas. Firstly we applied the pressures-observing system to evaluate concentration of ozone in an O3/O2 gas mixture. The results indicated that this method allows a concentration measurement of ozone with an accuracy of Δ Cozone = 0.2 vol%, near atmospheric pressure. Secondly, we used an impedance measurement system of a quartz oscillator and we estimated the accuracy at A Cozone = 0.05 vol%.

• 最新の酸化膜作製技術とその応用

一村 信吾, 斎藤 芳男

應用物理   72 ( 6 ) 777 - 778  2003.06

• 一村信吾, 野中秀彦, 黒河明, 中村健

電子材料   42 ( 5 ) 36 - 41  2003.05

• 一村信吾, 野中秀彦

クリーンテクノロジー   13 ( 3 ) 16 - 19  2003.03

• 田中 彰博, 一村 信吾, 田沼 繁夫

Journal of surface analysis   8 ( 3 ) 514 - 525  2002.11

• 一村 信吾

Journal of surface analysis   8 ( 3 ) 423 - 432  2002.11

• Application of 100% ozone gas process to rapid low-temperature oxidation

H Nonaka, S Ichimura, T Nishiguchi, Y Morikawa, M Kekura, M Miyamoto

10TH IEEE INTERNATIONAL CONFERENCE ON ADVANCED THERMAL PROCESSING OF SEMICONDUCTORS - RTP 2002     119 - 123  2002  [Refereed]

View Summary

100% ozone oxidation process has been applied for the first time to rapid low-temperature oxidation of silicon to fabricate device quality SiO2 films. A new quartz cold wall-type furnace equipped with a halogen lamp heater was built for safe and efficient handling of 100% ozone gas supplied from a pure ozone generator which we have developed. The working pressure of the furnace was typically 900 Pa, which resulted in the growth of 4 nm SiO2 film within 4 min at 400 degreesC. A very low excitation energy observed for the SiO2 film growth indicates that the actual reacting species in the process are active oxygen radicals generated from the thermal decomposition of ozone molecules at the sample surface. The electrical properties of ozone-oxidized SiO2 films were evaluated by measuring the C-V and I-V characteristics of the MIS structure with Al electrodes. The films fabricated at 400-600 degreesC with thickness of 5-11 nm all show the properties matching the device quality, i.e. low interface state density (&lt;5x10(10) cm(-2) eV(-1)) and high breakdown voltage (&gt;13 MVcm(-1)).

• Electron emitter using MIM tunneling junction on ferromagnetic substrate

ITOH Hiroshi, NONAKA Hidehiko, ICHIMURA Shingo

44 ( 3 ) 377 - 377  2001.03

• Atomic force microscopy observation of layer-by-layer growth of ultrathin silicon dioxide by ozone gas at room temperature

MAEDA T, KUROKAWA A, SAKAMOTO K, ANDO A, ITOH H, ICHIMURA S

J. Vac. Sci. Technol. B   19 ( 2 ) 589 - 592  2001

• Directional mass analysis of ozone dissociation during thin oxide formation with highly concentrated ozone

A Kurokawa, K Nakamura, S Ichimura

CHARACTERIZATION AND METROLOGY FOR ULSI TECHNOLOGY 2000, INTERNATIONAL CONFERENCE   550   191 - 195  2001  [Refereed]

View Summary

A directional mass analyzer (DMA) selectively detects the molecules flying from a sample surface. The analysis with the DMA for ozone oxidation of silicon surfaces, which gives the reaction rate of ozone molecule on substrate surface, was applied for in-situ analysis for ultra-thin oxide fabrication with highly concentrated ozone. Since atomic oxygen generated by the ozone dissociation dominantly contributes to the substrate oxidation, in-situ monitoring of the dissociation rate will help control oxidation processes. The analysis showed that the dissociation rate of ozone on a pre-oxidized Si surface increased when the substrate temperature increased up to 400 degreesC, then the tool is especially useful for ozone oxidation at low temperature.

• A. Kurokawa, S. Ichimura, H. Nonaka, H. Hojyo

Shinku/Journal of the Vacuum Society of Japan   44 ( 3 ) 167 - 170  2001

View Summary

To measure concentration of binary mixture gas we developed a new method that uses a Quartz gauge together with a capacitance manometer. Because a Quartz gauge's sensor is sensitive to both gas viscosity and gas pressure while a capacitance manometer is just sensitive to gas pressure, the viscosity of the gas can be estimated from pressure indication from both the gauges. If the gas is binary mixture gas and the viscosity of the gas changes monotonically with the concentration, the pressure deviation will give the concentration of binary mixture gas. This method has several merits. One is that we can apply to explosive gases because the sensors do not have any source to ignite such as a heated wire, an energetic light, and an electron source. The other is that because of no source to decompose the gas, this method does not change the concentration of the sample gas after the measurement. Then it is not necessary to discard the sampled gas, and the consequently the effective amount of the sample is negligible.

• H. Nonaka, A. Kurokawa, S. Ichimura, T. Nishiguchi, Y. Morikawa, M. Miyamoto

Shinku/Journal of the Vacuum Society of Japan   44 ( 3 ) 221 - 224  2001

View Summary

We built a new type ozone killer based on the redox reactions between cuprous and cupric oxides and applied it to the decomposition of low-pressure highly concentrated ozone. The analysis of the exhaust gas from the ozone killer by low-temperature thermal desorption measurement shows that ozone flux of 1.6 PaLs-1 can be decomposed completely to oxygen when the copper fins in the ozone killer were heated to 470°C. The copper fins, however, must be kept at even higher temperatures to decompose continuous and larger-flux of ozone since the oxidation of the fins turned out to proceed into the bulk at 470°C.

• 野中秀彦, 西口哲也, 森川良樹, 宮本正春, 一村信吾

J Surf Anal   7 ( 3 ) A.20-A.21  2000.12

• Fabrication of spin-polarized electron emitter from MIM tunnel junction II

Itoh Hiroshi, Nonaka H., Ichimura Shingo

Meeting abstracts of the Physical Society of Japan   55 ( 2 ) 785 - 785  2000.09

• Development of "Extreme technology" in Vacuum

ICHIMURA Shingo

62   129 - 129  2000.05

• Experimental Production of a Large Capacity-High Purity Ozone Beam Generator

MORIKAWA Yoshiki, NISHIGUCHI Tetsuya, MIYAMOTO Masaharu, ICHIMURA Shingo, NONAKA Hidehiko, KAWADA Masakuni, MURAKAMI Hiroshi

43 ( 3 ) 427 - 427  2000.03

• MIM, MIS-type electron emitter fabricated by ozone

Itoh Hiroshi, Nakamura Ken, Kurokawa Akira, Ichimura Shingo

Meeting abstracts of the Physical Society of Japan   55 ( 1 ) 755 - 755  2000.03

• Initial stage of ozone oxidation investigated by STM

Itoh Hiroshi, Nakamura Ken, Kurokawa Akira, Ichimura Shingo

Meeting abstracts of the Physical Society of Japan   55 ( 1 ) 787 - 787  2000.03

• 黒河 明, 一村 信吾, 中村 健

電総研ニュース   ( 600 ) 10 - 12  2000.01

• Growth mechanism of SiO2 ultra-thin film on Si(100) by highly concentrated ozone supplied at low and high pressure conditions

S Ichimura, K Nakamura, A Kurokawa, H Itoh, K Koike

PHYSICS AND CHEMISTRY OF SIO2 AND THE SI-SIO2 INTERFACE - 4   2000 ( 2 ) 67 - 77  2000  [Refereed]

View Summary

The growth mechanism of SiO2 thin film on Si(100) substrate by ozone was investigated. Two types of ozone generators were specially designed and fabricated for this purpose. The first ozone generator (type 1) supplies high purity ozone gas (&gt;80%) under low pressure condition (typically; 10(-4) Pa), while the second one (type 2) supplies about 25% ozone gas at atmospheric pressure condition. The initial stage of the SiO2 film growth on Si(100) was investigated using the type 1 generator. It was found for the ozone exposure at the substrate temperature of 700 degrees C that the SiO2, film thickness showed stepwise increase with exposure time up to 0.6 nm, and then showed linear increase with time for further increase of the ozone exposure. The linear increase with prolonged ozone exposure was observed only when the substrate temperature was &gt; 550 degrees C. Step and terrace structures were clearly observed by AFM on the SiO2 film with thickness of 0.6 nm when the Si substrate originally had the structures. By applying the type 2 generator, about 2.5 nm thick SiO2 film could be formed on the Si(100) substrate kept at 350 degrees C, The AFM observation of the SiO2, film revealed that the step/terrace structures were still observable, although the contrast of the structures were not so clear as that observed on the 0.6 nm thick SiO2 film. The formed SiO2 film was then chemically etched with dilute HF solution to reveal the interface. It was confirmed by the STM observation of the interface that the sharpness of the Si/SiO2, interface was not deteriorated by the SiO2, film growth at 350 degrees C, and that the film growth by ozone occurs in layer-by-layer manner.

• Akira Kurokawa, Shingo Ichimura, Ken Nakamura, Hiroshi Itoh

Shinku/Journal of the Vacuum Society of Japan   43 ( 3 ) 247 - 250  2000

View Summary

The sample contamination in a loadlock chamber, caused by particle sticking, adsorption of gas and moisture in a loadlock chamber and back stream from pumping systems, was investigated. In order to eliminate the first two sources of contamination, a clean silicon sample was prepared in a glove box filled with particle-free nitrogen gas, and the sample was transferred to the loadlock chamber without exposing to air. To observe the contamination during pumping, the last source of contamination, a clean sample was set in the loadlock chamber and after evacuation surface contaminant was evaluated by C1s intensity of XPS spectra. Several evacuation procedures were compared and we concluded that oil-free pumping system is essentially important for contaminant-free introduction of a clean sample.

• Tetsuya Nishiguchi, Yoshiki Morikawa, Masaharu Miyamoto, Hidehiko Nonaka, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   43 ( 3 ) 201 - 204  2000

View Summary

In order to obtain an active ozone beam and make full use of ozone oxidation ability, we used laser ablation method. High concentration ozone from an ozone jet generator was solidified on a sapphire substrate and then pulsed KrF laser was irradiated to the solid ozone. Ablated species and their velocity distribution have been investigated using time-of-flight method through a quadrupole mass filter. Ablated species were mainly a mixture of ozone, molecular oxygen and atomic oxygen. As for their velocity distribution, ozone showed a thermal equilibrium, while molecular oxygen showed many slower components. Ablated ozone yields were strongly dependent on laser power and showed a maximal. The ratio of ozone against molecular oxygen in the mixture increased as the substrate temperature became higher, probably because of increase in the purity of the solid ozone on the substrate. Ozone velocity varied from 1500 K to 2500 K depending on the laser power and the substrate temperature, which means that we can supply an ozone beam that has controlled purity and velocity.

• Hidehiko Nonaka, Tetsuya Nishiguchi, Yoshiki Morikawa, Masaharu Miyamoto, Shingo Ichimura

Materials Research Society Symposium - Proceedings   617   J131 - J136  2000

View Summary

Species ablated from solid ozone by a UV laser were investigated using a time-of-flight method through a quadrupole mass filter. The results show that UV-laser ablation of solid ozone can produce a pulsed ozone beam with a translational energy far above that of room temperature. High-concentration ozone from an ozone jet generator is solidified on a sapphire substrate attached to a copper block which is cooled to 30 to 60 K on a cryocooler head and the solid ozone is irradiated by pulsed laser light from a KrF laser (248 nm). The ablated species were a mixture of ozone and molecular oxygen as well as atomic oxygen due to photodissociation of ozone. At a substrate temperature of 30 K, the total amount of ablated ozone increases as the laser fluence increases to 13 mJcm-2. Beyond this fluence, enhanced decomposition of ozone occurs. Gaussian fitting of the time-of-flight signals of the ablated ozone reveals an average thermal energy exceeding 1,500 K. The velocity also increases when the laser fluence enters saturation at 2,300 K at 13 mJcm-2.

• 黒河 明, 一村 信吾, 中村 健

電子技術総合研究所彙報   63 ( 12 ) 501 - 507  1999.12

• A. Kurokawa, S. Ichimura, K. Nakamura

Denshi Gijutsu Sogo Kenkyusho Iho/Bulletin of the Electrotechnical Laboratory   63   19 - 25  1999.12

View Summary

To investigate the interfacial Si-displacement of an ultrathin silicon dioxide formed by oxidation of a Si(100) substrate with atmospheric-pressure ozone at a substrate temperature of 375 °C, we examined the structure around the interface of SiO2 and Si using medium-energy ion scattering spectroscopy (MEIS). A thermally grown oxide with the same thickness as an ozone-formed oxide was also measured with MEIS for comparison. The ozone-formed oxide film exhibited considerably less Si-displacement in the oxide layers near the interface than a thermally grown oxide film, which indicates that an ozone oxide film is homogenous. These results explain well our previous findings that an ozone oxide film exhibits a constant HF etching rate while a thermally grown oxide film slows the etching rate near the interface.

• 黒河 明, 一村 信吾, 中村 健

Science & technonews Tsukuba   ( 52 ) 23 - 25  1999.10

• 一村 信吾

季刊筑波研究コンソ-シアム   3 ( 2 ) 77 - 97  1999.09

• Characteristics of the Ozone by the Microwave Ion Source

MURAKAMI Hiroshi, KAMEYAMA Ikuya, ICHIMURA Shingo, SUKENOBU Satoru

42 ( 3 ) 479 - 480  1999.03

• Directivity of Directional Mass Analyzer for Observation of Ozone Reaction

KUROKAWA Akira, ICHIMURA Shingo, NAKAMURA Ken

42 ( 3 ) 468 - 468  1999.03

• Development of high purity one ATM ozone source - Its application to ultrathin SiO2 film formation on Si substrate

K Koike, G Inoue, S Ichimura, K Nakamura, A Kurokawa, H Nonaka

ULTRATHIN SIO2 AND HIGH-K MATERIALS FOR ULSI GATE DIELECTRICS   567   121 - 126  1999  [Refereed]

View Summary

A high-concentration ozone generator operating at atmospheric pressure has been developed for fabrication of ultra thin silicon oxide films. The generator can supply atmospheric pressure of ozone jet with ozone concentration up to 80 vol%. The ozone jet is generated by desorbing ozone at nearby room temperature. which has been condensed on silica-gel by passing ozone/oxygen mixture gas from a commercial ozonizer at a low temperature (&lt;-50 degrees C); at the temperature ozone is more selectively adsorbed on silica-gel than oxygen. The high purity ozone jet with a concentration of 25 vol% at a pressure of Ix 10(5) Pa had so large oxidation power that SiO2 film as thick as 3.3 nm grew on a Si surface after 60 min exposure at 375 degrees C. The density of the film was equivalent to that of the film formed by a conventional thermal oxidation process: judging from etching rate with dilute HF solution.

• Ultrathin silicon dioxide formation by ozone on ultraflat Si surface

A Kurokawa, T Maeda, K Sakamoto, H Itoh, K Nakamura, K Koike, DW Moon, YH Ha, S Ichimura, A Ando

ULTRATHIN SIO2 AND HIGH-K MATERIALS FOR ULSI GATE DIELECTRICS   567   21 - 26  1999  [Refereed]

View Summary

We prepared an atomically flat silicon substrate which had a step-terrace structure and observed the topography of the ozone-oxidized surface to clarify whether homogeneous oxidation occurs with ozone. The oxide was formed with high-concentration ozone gas with a thickness of 2.5nm at a temperature of 350 degrees C. The oxide surface still maintained the same step-terrace structure as observed before oxidation, which revealed that ozone-oxidation occurs layer-by-layer and produces an atomically flat oxide. XPS and MEIS analyses show that the stoichiometry of ozone oxide grown at 350 degrees C is the same as that of an oxide grown thermally at 750 degrees C.

• K Koike, G Inoue, S Ichimura, K Nakamura, A Kurokawa, H Nonaka

ULTRATHIN SIO2 AND HIGH-K MATERIALS FOR ULSI GATE DIELECTRICS   567   121 - 126  1999

View Summary

A high-concentration ozone generator operating at atmospheric pressure has been developed for fabrication of ultra thin silicon oxide films. The generator can supply atmospheric pressure of ozone jet with ozone concentration up to 80 vol%. The ozone jet is generated by desorbing ozone at nearby room temperature. which has been condensed on silica-gel by passing ozone/oxygen mixture gas from a commercial ozonizer at a low temperature (&lt;-50 degrees C); at the temperature ozone is more selectively adsorbed on silica-gel than oxygen. The high purity ozone jet with a concentration of 25 vol% at a pressure of Ix 10(5) Pa had so large oxidation power that SiO2 film as thick as 3.3 nm grew on a Si surface after 60 min exposure at 375 degrees C. The density of the film was equivalent to that of the film formed by a conventional thermal oxidation process: judging from etching rate with dilute HF solution.

• S. Ichimura, H. Nonaka, A. Kurokawa, K. Nakamura

Vide: Science, Technique et Applications     100 - 109  1998.12

View Summary

A new ozone jet generator which can supply high purity ozone beam was specially fabricated, and applied to the formation and characterization of oxide thin films. After careful investigation of SiO2 thin film formation on Si substrates using either ozone or molecular oxygen, it was confirmed that; i) an atomic oxygen generated at dissociation of ozone attacks a back bond of Si to form Si-O-Si bonding, ii) the suboxide (SiOx; x&lt;2) formation at the SiO2/Si interface was suppressed by the ozone oxidation, and iii)a stable SiO2 film was formed by the ozone exposure at a higher substrate temperature (&gt;about 300°C). It was also confirmed that ozone exposure during surface analysis using an electron beam could diminish (and erase) sample charging even the the thickness of a SiO2 sample is in the order of sub mm.

• Measurement of the Outgassing Rate from the XHV Chamber Fabricated for Pressure Measurement and Calibration in UHV/XHV Region

ICHIMURA Shingo, KOKUBUN Kiyohide, HIRATA Masahiro, TSUKAHARA Sonoko, SAITO Kazuya, IKEDA Yoshinao

41 ( 3 ) 336 - 336  1998.03

• Distribution of Auger Electron Analyzed by Instrument for Surface Electron Spectroscopic Tomography

KUROKAWA Akira, ICHIMURA Shingo

41 ( 3 ) 365 - 365  1998.03

• Ozone-Oxidation of Hydrogen-Terminated Si Surface

KUROKAWA Akira, ICHIMURA Shingo, NAKAMURA Ken

41 ( 3 ) 390 - 390  1998.03

• Information Depth of Second Harmonic Generation (SHG) on Silicon Surfaces

NAKAMURA Ken, ICHIMURA Shingo

41 ( 3 ) 389 - 389  1998.03

• Application of high-purity ozone beam to silicon-oxide thin-film formation and surface cleaning

ICHIMURA Shingo, KUROKAWA Akira, NAKAMURA Ken, NONAKA Hidehiko

OYOBUTURI   67 ( 6 ) 673 - 677  1998

• Hydrogen passivation and ozone oxidation of silicon surface

A Kurokawa, K Nakamura, S Ichimura

HYDROGEN IN SEMICONDUCTORS AND METALS   513   37 - 42  1998  [Refereed]

View Summary

The oxidation of H/Si(100) and H/Si(111) with high concentration. ozone gas was investigated with X-ray photoelectron spectroscopy(XPS). The ozone oxidation of partially hydride-covered surface was observed. The hydrogen termination reduced the rate of oxygen insertion into silicon backbond. The reduction of oxygen insertion rate by the H-termination for H/Si(100) was larger than that for H/Si(111). The dissociation rate of ozone molecule on H/Si was estimated to be similar or equal to 0.2 with a directional mass analyzer.

• In-situ surface and interface characterization by optical second harmonic generation (SHG) of silicon dioxide fabrication with high purity ozone

K Nakamura, A Kurokawa, S Ichimura

CHARACTERIZATION AND METROLOGY FOR ULSI TECHNOLOGY   449   326 - 330  1998  [Refereed]

View Summary

Second harmonic generation (SHG) on silicon surfaces, giving signals only from surfaces and interfaces, was applied for in-situ analysis of ultra-thin oxide fabrication by high purity ozone. In addition to its capability of in-situ measurement, the characteristics of SHG analysis by use of fundamental Nd:YAG laser beam on silicon surfaces is highlighted with such merit as continuous observation of surface and film growth processes and information depth limited to outermost surface layer. However, such limitation as angular condition of optical path must be also considered due to the symmetry of surface structure.

• Yoshinao Ikeda, Kazuya Saito, Sonoko Tsukahara, Shingo Ichimura, Kiyohide Kokubun, Masahiro Hirata

Shinku/Journal of the Vacuum Society of Japan   41 ( 5 ) 507 - 511  1998

View Summary

Coating of titanium nitride TiN film on stainless steel by hollow cathode discharge method under the controlled conditions has been developed and could reduce outgassing rate at the extremely high vacuum due to the hydrogen barrier effect of TiN1-3). This paper reports 1. further reduction of hydrogen permeation constant K of TiN film, 2. application of this technique to practical chamber preparation, and 3. reduction of outgassing rate of the resulting chamber. Hydrogen permeation constant of TiN films prepared by a laboratory equipment was decreased by improving the film structure to more dense and larger grains. The minimum hydrogen permeation constant K of TiN film at 500°C was 6 × 10-13Pa1/2·m2·s-1. Considering the above result, the practical condition of manufactuaring equipment was adjusted to make large samples for new XHV chambers fabricated for standard pressure measurement by Electrotechnical Laboratory in Japan. The resulting outgassing rate of a TiN coated chamber was measured by switching between two pumping paths (SPP) method at room temperature. At the ultimate pressure the outgassing rates of the stainless steel chamber was 3 × 10-12 Pa·m·s-1 after the prebaking of (430°C × 100 h + 500°C × 100 h) and after TiN coating on the chamber it decreased to less than 1 × 10-13 Pa·m·s-1, the lowest value obtained for stainless steel.

• S. Ichimura, H. Nonaka, A. Kurokawa, K. Nakamura

Proceedings of the International Conference on Electric Charge in Solid Insulators, CSC     100 - 109  1998.01

View Summary

A new ozone jet generator which can supply high purity ozone beam was specially fabricated, and applied to the formation and characterization of oxide thin films. After careful investigation of SiO2 thin film formation on Si substrates using either ozone or molecular oxygen, it was confirmed that; i) an atomic oxygen generated at dissociation of ozone attacks a back bond of Si to form Si-O-Si bonding, ii) the suboxide (SiOx; x&lt;2) formation at the SiO2/Si interface was suppressed by the ozone oxidation, and iii) a stable SiO2 film was formed by the ozone exposure at a higher substrate temperature (&gt;about 300 °C). It was also confirmed that ozone exposure during surface analysis using an electron beam could diminish (and erase) sample charging even the thickness of a SiO2 sample is in the order of sub mm.

• 野中秀彦, 一村信吾

表面科学   18 ( 12 ) 810  1997.12

• 一村信吾, 中村健, 黒河明, 野中秀彦, 村上寛

電子情報通信学会技術研究報告   97 ( 220(CPM97 52-60) ) 13 - 18  1997.08

• 野中秀彦, 一村信吾

Ionics   23 ( 7 ) 63 - 68  1997.07

• Surface oxidation of Si (111) by high purity ozone and negative ions produced by Rydberg electron transfer

H Nonaka, A Kurokawa, K Nakamura, S Ichimura

AMORPHOUS AND CRYSTALLINE INSULATING THIN FILMS - 1996   446   53 - 58  1997  [Refereed]

View Summary

The sub-initial oxidation of Si (111) surface by a high-flux pure ozone was investigated using X-ray photoelectron spectroscopy. In addition to the advantage of the pure ozone which can efficiently oxidize the Si surface at room temperature, the high-flux ozone was found to further enhance the oxidation. The possibility of producing negative ions of oxidizing gases using Rydberg electron transfer was also investigated.

• Ozone cleaning of carbon-related contaminants on Si wafers and other substrate materials

H Nonaka, A Kurokawa, S Ichimura, DW Moon

SCIENCE AND TECHNOLOGY OF SEMICONDUCTOR SURFACE PREPARATION   477   493 - 498  1997  [Refereed]

View Summary

We have investigated a novel surface cleaning technique of native oxide on Si wafer, in which carbon-related contaminants are removed effectively at room temperature with a pure ozone beam from an ozone jet generator that we developed. Although ozone alone was likely to be little reactive to saturated carbons and byproducts in the reaction of ozone with unsaturated carbons which could be assigned to either carbonyl-or carboxyl-related compounds, a high-dose pure ozone under ultraviolet light irradiation to generate atomic oxygen by the photo-dissociation of ozone removed most of them at room temperature. The effectiveness of the ozone cleaning was also demonstrated for selected oxide surfaces.

• Comparison of high-purity-ozone oxidation on Si(111) and Si(100)

A Kurokawa, S Ichimura, DW Moon

SCIENCE AND TECHNOLOGY OF SEMICONDUCTOR SURFACE PREPARATION   477   359 - 364  1997  [Refereed]

View Summary

The oxidation of Si(111) and Si(100) surfaces with the high-purity ozone(mo-e than 98 mole %) was investigated with X-ray photoelectron spectroscopy (XPS). Thin oxide less than 3nm thickens was formed in an experimental chamber and the results showed that ozone oxidizes the (111) surface faster than (100) surface. Ozone does not show the temperature dependence on oxidation within the temperature range of 250-500 degree C for both (111) and (100) surfaces. Ozone proceeds the oxide formation at 700 degree C where oxygen does not proceed oxide formation rapidly.

• Hiroshi Murakami, Hug J. Kang, Akira Kurokawa, Ken Nakamura, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   40 ( 3 ) 333 - 335  1997

• Akira Kurokawa, Shingo Ichimura

Shinku/Journal of the Vacuum Society of Japan   40 ( 3 ) 177 - 179  1997

• On the 9th International Conference on Quantitative Surface Analysis "QSA-9"

TANUMA Shigeo, ICHIMURA Shingo

17 ( 10 ) 619 - 620  1996.10

• 一村信吾

工業技術   37 ( 8 ) 30 - 31  1996.08

• 黒河 明, 一村 信吾

電子技術総合研究所調査報告   ( 226 ) 83 - 88  1996.03

• 中村 健, 一村 信吾

電子技術総合研究所調査報告   ( 226 ) 55 - 62  1996.03

• Shigeyuki Sekine, Shingo Ichimura, Akira Kurokawa, Akira Iwasaki

Shinku/Journal of the Vacuum Society of Japan   39 ( 3 ) 115 - 117  1996

• Low temperature oxidation processing with high purity ozone

A Kurokawa, S Ichimura, HJ Kang, DW Moon

RAPID THERMAL AND INTEGRATED PROCESSING V   429   269 - 274  1996  [Refereed]

• XHV Pressure Measurement by Laser Ionization -Possibility of Molecular Density Measurement-

ICHIMURA Shingo, SEKINE Shigeyuki, KOKUBUN Kiyohide, SHIMIZU Hazime

38 ( 9 ) 790 - 790  1995.09

• Improvement of the Sensitivity of XHV Pressure Measurement by Laser Ionization Method

KOKUBUN Kiyohide, SEKINE Shigeyuki, ICHIMURA Shingo, KUROKAWA Akira, SHIMIZU Hazime

38 ( 9 ) 791 - 791  1995.09

• Sensitivity of Ion-Imaging Method and Mass Analysis using an Imaging Detector

SEKINE Shigeyuki, ICHIMURA Shingo, KUROKAWA Akira, IWASAKI Akira, KOKUBUN Kiyohide, SHIMIZU Hazime

38 ( 9 ) 792 - 792  1995.09

• Adsorption of Benzene on Si(111)7×7 at Room Temperature Observed by Second Harmonic Generation (SHG)

NAKAMURA Ken, ICHIMURA Shingo

真空   38 ( 9 ) 778 - 778  1995.09

• Observation of Surface by Surface Electron Spectroscopic Tomography

KUROKAWA Akira, ICHIMURA Shingo, YOSHIHARA Kazuhiro

真空   38 ( 9 ) 777 - 777  1995.09

• 一村信吾

エレクトロニクス   39 ( 10 ) 89 - 92  1994.10

• Direct Estimation of the Ionization Region for XHV Measurement by Laser Ionization

ICHIMURA Shingo, SEKINE Shigeyuki, KOKUBUN Kiyohide, KUROKAWA Akira, SHIMIZU Hazime

37 ( 9 ) 784 - 785  1994.09

• 4a-Q-11 Second-order Nonlinear Optical Properties of Si(111)7×7 Investigated by Monohydride and Polyhydride Adsorption

Nakamura K, Ichimura S, Shimizu H

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1994 ( 2 ) 415 - 415  1994.08

• 31a-WC-12 Second-Order Nonlinear Optical Properties of Si(111)7x7 Effected by Hydrogen Adsorption

Nakamura K, Ichimura S, Shimizu H

Abstracts of the meeting of the Physical Society of Japan. Annual meeting   49 ( 2 ) 494 - 494  1994.03

• Shigeyuki Sekine, Kiyohide Kokubun, Shingo Ichimura, Akira Kurokawa, Hazime Shimizu

Shinku   37 ( 3 ) 285 - 288  1994

• T WADA, T KANAYAMA, S ICHIMURA, Y SUGIYAMA, M KOMURO

PHYSICS AND APPLICATIONS OF DEFECTS IN ADVANCED SEMICONDUCTORS   325   67 - 72  1994

View Summary

The effects of low-energy electron irradiation on the two-dimensional electron gases (2DEG&#039;s) in AlGaAs/GaAs heterostructures have been investigated. Not only the electron mobility of the 2DEG&#039;s but also the two-dimensional (2D) carriers are found to be reduced by the electron irradiation with the incident energies between 3.5 k and 8 keV and the electron dose of 1×1016 and 1×1017/cm2. The degraded mobility and the removed carriers by the low-energy electron irradiation are shown to recover by isochronal annealing to some extent, but not completely below 400 °C. It is also found that considerable amount of scatterers which are created by an electron irradiation at room temperature are also created by an irradiation at 90 K. Comparing the experimental results with the Monte Carlo simulation, we speculate that the mobility degradation and the 2D carrier compensation are partly caused by the formation of complex defects in the GaAs buffer layer which are due to the excitations of core electrons of As, and that the mobility is further degraded by the formation of short-range scatterers in the heterointerface.

• Shigeyuki Sekine, Kiyohide Kokubun, Shingo Ichimura, Hazime Shimizu

shinku   37 ( 9 ) 714 - 717  1994

View Summary

The measurement of gas pressure in ultrahigh vacuum was carried out by detecting laser-generated photoelectrons. Xenon atoms filling a vacuum chamber were nonresonantly ionized by a picosecond laser pulse. The laser intensity dependence of the number of ions produced was measured, and almost all xenon atoms in a focal area were found to be ionized. The number of photoelectrons produced was also measured as a function of xenon pressure. The signal intensity was proportional to xenon pressure in the range from 10-2 to 10-7 Pa. © 1994, The Vacuum Society of Japan. All rights reserved.

• Kiyohide Kokubun, Shigeyuki Sekine, Shingo Ichimura, Akira Kurokawa, Hazime Shimizu

shinku   37 ( 9 ) 711 - 713  1994

View Summary

By means of nonresonant multiphoton ionization using a picosecond pulsed YAG laser, pressure measurement for H2, CO and CO2 gases was carried out in the XHV pressure range. It was experimentally verified that pressure measurement was possible in the range of 10-11 Pa, and this pressure measurement method had pressure sensitivity of the same order of magnitude for the three molecules. © 1994, The Vacuum Society of Japan. All rights reserved.

• 14a-DH-7 A STM study of trimethyl-and triethyl-gallium decomposition on Si surfaces.

Fukui K., Mizutani W., Onishi H., Ichimura S., Shimizu H., Iwasawa Y.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1993 ( 2 ) 531 - 531  1993.09

• 一村 信吾, 細川 俊介, 清水 肇

電子技術総合研究所彙報   57 ( 4 ) p300 - 313  1993.04

• 国分 清秀, 清水 肇, 一村 信吾

電子技術総合研究所彙報   57 ( 4 ) p336 - 343  1993.04

• Shigeyuki Sekine, Kiyohide Kokubun, Shingo Ichimura, Hazime Shimizu

Shinku/Journal of the Vacuum Society of Japan   36 ( 3 ) 322 - 324  1993

• K. Kokubun, H. Shimizu, S. Ichimura

Denshi Gijutsu Sogo Kenkyusho Iho/Bulletin of the Electrotechnical Laboratory   57   38 - 44  1993.01

View Summary

Residual gases in an extreme-high vacuum (XHV) system are measured at each pumping step. On the basis of the analysis, the pumping capacity of each vacuum pump is estimated. As a result, it is found that, in the case of a liquid N2-cooled shroud, the titanium-sublimation pump has a high capacity for evacuating of Ch4and Ar as well as H2gas, and a pumping system which consists of two turbo molecular pumps and a rotary pump has a pumping capacity for almost all gases in the region of ultra high vacuum, but loses the capacity for H2gas in the XHV region.

• S. Sekine, H. Hashizume, S. Ichimura, H. Shimizu

Denshi Gijutsu Sogo Kenkyusho Iho/Bulletin of the Electrotechnical Laboratory   57   16 - 23  1993.01

View Summary

The molecular beam was obtained by a laser ablation of condensed NO2on a cold substrate. The ejected particles were NO2molecules and had a sharp angular distribution around surface normal. The translational energy was measured as a function of (1) laser power density and (2) an amount of the adsorbed NO2. The beam had approximately thermal distribution of the translational energy and the temperature was in the range from 200 K to 1200 K. In experiment to demonstrate the beam as an oxygen source the surface of a copper target was fully oxidized to CuO.

• S. Ichimura, S. Hosokawa, H. Shimizu

Denshi Gijutsu Sogo Kenkyusho Iho/Bulletin of the Electrotechnical Laboratory   57   2 - 14  1993.01

View Summary

An ozone jet generator was constructed to supply oxidizing reagent with high reactivity and low kinetic velocity, and was applied to the preparation of superconducting oxide thin films by an MBE method. Ozone jet was generated by evaporating the liquid (or solid) ozone accumulated in the ozone vessel of the generator. Precise pressure and temperature control of the ozone vessel in liquefying and evaporating ozone makes it possible to generate ozone jet with high purity, controllability, and reactivity which was evaluated by mass analysis, XPS analysis, etc. Some applications of the ozone jet generator in fabrication of superconducting oxide thin films were also reported.

• New technique for extreme high vacuum (XHV) measurement

KOKUBUN Kiyohide, ICHIMURA Shingo, SHIMIZU Hazime, OKANO Tatsuo, TERADA Keiko

OYOBUTURI   61 ( 12 ) 1284 - 1285  1992

• NONAKA Hide-hiko, HOSOKAWA Shunsuke, SAKAI Shigeki, ICHIMURA Shingo

OYOBUTURI   61 ( 5 ) 512 - 513  1992

• 28p-APS-52 Preparation and growth mechanism of YBa_2Cu_3O_<7-δ>thin films by sequential deposition

Shimizu T., Nonaka H., Hosokawa S., Ichimura S., Arai K.

46 ( 3 ) 339 - 339  1991.09

• 細川 俊介, 一村 信吾

電子技術総合研究所彙報   55 ( 3 ) p395 - 401  1991.03

• KOKUBUN Kiyohide, SHIMIZU Hazime, ICHIMURA Shingo, Kawahara Humio, KONDO Minoru

Shinku   34 ( 3 ) 223 - 225  1991

• KOKUBUN Kiyohide, SHIMIZU Hazime, ICHIMURA Shingo, KAWAHARA Humio, KONDO Minoru

Shinku   34 ( 1 ) 14 - 16  1991

• 国分 清秀, 清水 肇, 一村 信吾

電子技術総合研究所彙報   54 ( 12 ) p1507 - 1512  1990.12

• 一村信吾

学術月報   43 ( 9 ) 832 - 835  1990.09

• Effect of Laser Wavelength on Nonresonant Multiphoton Ionization

Kokubun K., Ichimura S., Shimizu H.

45 ( 4 ) 33 - 33  1990.03

• 越川 孝範, 一村 信吾

真空   33 ( 2 ) p69 - 71  1990.02

• KOKUBUN Kiyohide, ICHIMURA Shingo, HASHIZUME Hiroko, SHIMIZU Hazime

Shinku   33 ( 3 ) 104 - 106  1990

• 大門 寛, 一村 信吾

真空   32 ( 2 ) 85 - 91  1989

• Kiyohide Kokubun, Hiroko Hashizume, Hajime Shimizu, Shingo Ichimura, Yoshiro Oowadano, Yuji Matsumoto, Kazuhiro Endo

Shinku/Journal of the Vacuum Society of Japan   32 ( 3 ) 399 - 402  1989

• 31a-G1-3 稀ガスの非共鳴多光子吸収イオン化(量子エレクトロニクス・原子・分子合同セッション)

国分 清秀, 橋詰 宙子, 清水 肇, 一村 信吾, 大和田野 芳郎, 松本 裕治

年会講演予稿集   43 ( 2 ) 286 - 286  1988.03

• 31a-G1-3 稀ガスの非共鳴多光子吸収イオン化(量子エレクトロニクス・原子・分子合同セッション)

国分 清秀, 橋詰 宙子, 清水 肇, 一村 信吾, 大和田野 芳郎, 松本 裕治

年会講演予稿集   43 ( 4 ) 18 - 18  1988.03

• Takuichi Ohmura, Akira Kurokawa, Ryuichi Shimizu, Teiichi Homma, Daisuke Fujita, Keisuke Goto, Masao Uemura, Heizo Tokutaka, Kazuhiro Yoshihara, Masayasu Kurahashi, Shingo Ichimura, Chuhei Oshima, Fusami Soeda, Yasuo Fukuda, Yoshihiro Hashiguchi, Kozo Tanaka, Masahiro Kudo, Takayoshi Hayashi, Akihiro Tanaka, Yoshiro Shiokawa, Tetsu Sekine

Shinku   31 ( 8 ) 744 - 754  1988

View Summary

Under the auspices of the 141 comittee (Microbeam Analysis) of Japan Society for Promotion of Science, the AES working group has commenced its work on 1) the establishment of the measurement conditions and 2) the comparison of standard spectra obtained by various spectrometers. Attention was particularly paid to taking the Auger signals at an optimum position of the specimen with respect to the energy analyzer. Systematic investigations on the procedures for energy analyzers, cylindrical mirror analyzers (CMA), are reported in the first section of the present paper. Three kinds of calibration procedures were proposed for attaining the optimum positioning of the specimen with respect to the CMA. Elastic peak varied sensitively in intensity and peak shape, around the optimum position of the specimen. The comparison of AES instruments installed at several institutes was carried out by measurement of the derivative Auger peak intensity ratio for pure gold and copper under a specific measurement condition, proposed in the first section. The results are shown by the Youden plot following the laborious work performed by the ASTM comittee E-42. © 1988, The Vacuum Society of Japan. All rights reserved.

• 一村 信吾

真空   30 ( 8 ) p673 - 678  1987.08

• H. Murakami, S. Ichimura, H. Shimizu, I. Kudo, S. Komaki, T. Tajima, Y. Tanaka, H. Naitho

83 - 86  1986.12

View Summary

Synchrotron Radiation (SR) is now attracting much attention as a promising source for X-ray lithography because of its high intensity and small divergence. In the usual way of fine pattern replication using SR, resist has been processed by wet chemical etching after exposure. Lithography by SR, however, generally requires vacuum conditions by the strong absorption of SR by air. Therefore, the resist process should be dry which in turn enables avoiding any pattern deterioration due to swelling during wet development. Recently, direct removal of resist materials by SR irradiation only has been observed. The objective of the present paper is to describe the design concept and the fundamental characteristics of a low energy reactive ion source, which has been designed for simultaneous use with SR to increase the direct engraving rate.

• Masanori Komuro, Hiroshi Hiroshima, Hajime Shimizu, Masatoshi Ono, Shingo Ichimura, Hiroshi Murakami, Mieko Sato

Denshi Gijutsu Sogo Kenkyusho Chosa Hokoku/Circulars of the Electrotechnical Laboratory    1984.01

View Summary

Point ion sources utilizing the ionization of atoms and molecules in high electric fields have been studied at several laboratories in the U. S. A. , European countries and Japan for a drastic improvement in the performance of apparatuses that use finely focused ion beams. It is the main objective of this report to investigate the present status of studies on the basic phenomena and applications of the field point ion sources. In Chapter 1, the technology for application of high-brightness ion sources is surveyed. Chapter 2 provides a scientific foundation for the gas-phase field ionization source. Chapter 3 discusses the present technology of ion optics for ion micro-beams of high brightness. Chapter 4 discussed improvements of gas-phase field ion sources. Refs.

• Lithography Experiments Using Synchrotron Radiation from ETL Storage Ring : LATE NEWS

HOH Koichiro, HIRATA Masahiro, ATODA Nobufumi, TANINO Hiroshi, ICHIMURA Shingo, ONUKI Hideo

Japanese journal of applied physics. Supplement   22 ( 1 ) 611 - 612  1983.02

• Shimizu Ryuichi, Ichimura Shingo

Denshi kenbikyo   16 ( 2 ) 136 - 141  1981

• Monte Carlo simulation for laser excition processes

FUJIWARA Etsuo, KATO Yoshiaki, ICHIMURA Shingo, SHIMIZU Ryuichi

The Review of Laser Engineering   8 ( 3 ) 524 - 537  1980

View Summary

Two types of Monte Carlo simulation programs for electron-beam excitation processes for a gaseous laser have been developed. One of them : type (A) was used for studying spatial distribution and uniformity of the energy deposition of the electron-beam inside the laser gas. Also the efficiency for energy deposition have been obtaind. E-beam excitation of laser gas from one side results in very nonuniform spatial excitation. Whereas uniform energy deposition is obtained by two-sides excitation or cylindrical excitation.<BR>The other program : type (B) treats individual processes of excitations, ionizations, and trajectories of secondary electrons. The average energy to produce an electron-ion pair for argon was determined to be 26.5 eV and 26.9 eV for incidence electron energy of5 keV and 50 keV respectively. For the electron-beam excited KrF laser, the upper laser level is formed about 72% via ions and 28% via excited states.

• Ryuichi Shimizu, Shingo Ichimura, Mikio Aratama

Proceedings, Annual Conference - Microbeam Analysis Society     30 - 34  1979.01

View Summary

A basic study is provided of the atomic number effect for quantitative AES analyses by Monte Carlo calculation technique. Since the direct simulation of each individual inelastic scattering process used in the previous papers applies to only a few materials, the authors have attempted to incorporate a semi-empirical stopping power formula proposed by E. R. Krefting and L. Reimer instead of the individual inelastic scattering. The result describes the dependence of Auger electron intensity on primary energy obtained with a commercial SAM, JEOL JAMP III, with considerable accuracy.

### Industrial Property Rights

• 酸化膜改質方法及び酸化膜改質装置

5487522号

西口哲也, 斉藤 茂, 亀田直人, 野中秀彦, 一村信吾

Patent

• 酸化膜形成方法

5403683

亀田直人, 野中 秀彦, 一村 信吾

Patent

• オゾン分解装置及びプロセスシステム

5391452

亀田直人, 西口哲也, 野中秀彦, 一村信吾

Patent

• オゾン濃度測定方法及びその装置

5239053

西口哲也, 野中秀彦, 一村信吾

Patent

• オゾン分解装置

5299857

西口哲也, 野中秀彦, 一村信吾

Patent

• AFMカンチレバー共振特性評価法

5224084

井藤浩志, 一村信吾

Patent

• ゲート絶縁膜の形成方法、半導体素子の製造装置

5702288

亀田直人, 西口哲也, 森川良樹, 花倉 満, 一村信吾, 野中秀彦

Patent

### Presentations

• Standardization of output data format for measurement and analysis instruments: current situation and future plan

Shingo ICHIMURA  [Invited]

Presentation date： 2022.01

Event date：
2022.01

• Japanese activities in ISO/TC 229 for international standardization of nanotechnologies

S. Ichimura  [Invited]

12th Nanotechnology Assocoation Conference

Presentation date： 2020.01

Event date：
2020.01

• Toward Construction of Measurement/Characterization Platform for Open Innovation

S. Ichimura  [Invited]

8th Intern. Symp. on Practical Surface Analysis (PSA-19)

Presentation date： 2019.11

Event date：
2019.11

• International Standardization of Nanotechnologies -Significance and Current Status-

S. ichimura  [Invited]

ImPACT International Symposium on InSECT 2016

Presentation date： 2016.04

• Significance of standardization in an era of global completion-case example of nanotechnology-

S. Ichimura  [Invited]

2nd KVS-VSJ-SSSJ Joint Symposium

Presentation date： 2013.11

• Standardization for Nano-technologies in an Era of Global Competion

S. ichimura  [Invited]

The 3rd Intern. Symp. on Advanced Composite Materials

Presentation date： 2012.11

• Recent standardization activities relating to measurement and characterization of nanotechnologies

S.Ichimura  [Invited]

The 3rd Intern. Symp. on SPM Standardization (SPM2012)

Presentation date： 2012.03

• Reseaerch activities of nanotechnology, materials and manufacturing technologies developed in AIST

S. Ichimura  [Invited]

Korea-China-Japan Manufacturing Industry Strategy Forum 2011

Presentation date： 2011.11

• Standardization of nano-structure/material measurement and characterization

S. Ichimura, H. Itoh, D. Fujita  [Invited]

18th International Vacuum Congress (IVC-18) and International Conference on Nanoscience and Technology (ICN+T 2010) and ICSS-14 and VASSCAA-5

Presentation date： 2010.08

• Standardization of Measurement and Characterization Methods for Nano-materials/structures

S. Ichimura  [Invited]

APEC Nanoproducts Measurement and Technology Forum

Presentation date： 2009.10

• Current standardization activities for nanomaterials/structure measurement and characterization

S. Ichimura, H. Itoh  [Invited]

International Union of Material Research Society-International Conference in Asia (IUMRS-ICA) 2008

Presentation date： 2008.12

• Current Activities of ISO TC229 on Nanotechnology for the Development of Purity Evaluation and Quality Assurance Standards for Carbon Nanotubes

S. Ichimura  [Invited]

2008 Materials Research Society (MRS) Fall Meeting

Presentation date： 2008.11

• Standardization of Measurement and Characterization Methods for Nanotechnology

S. Ichimura  [Invited]

Nanosymposium 2007

Presentation date： 2007.12

• Standardization of Measurement and Characterization Methods for Nanotechnology: Brief overview and practical examples

S.Ichimura  [Invited]

International Conference on Nanoscience & Technology, China 2007 (ChinaNANO 2007)

Presentation date： 2007.06

• Scanning Probe Microscopy in Global Standards

D. Fujita, H. Itoh, S. Ichimura, T. Kurosawa  [Invited]

Workshop on NC-AFM

Presentation date： 2006.07

• Distinctive feature of ozone and atomic oxygen in surface oxidation and oxide film growth

S.Ichimura  [Invited]

11th European Conf. on Applications of Surface and Interface Analysis (ECASIA05)

Presentation date： 2005.09

• Ultrathin SiO2 film growth on Si by highly concentrated ozone

S. Ichimura, A. Kurokawa, K. Nakamura, H. Itoh, H. Nonaka, K. Koike  [Invited]

Int. Conf. Metallurgical Coatings and Thin Films (ICMCTF2000)

Presentation date： 2000.04