The morphological evolution of zinc during electrodeposition from an alkaline zincate solution, i.e., corresponding to charging operation in secondary zinc batteries, was investigated. The initiation and propagation of mossy structures were particularly focused; mossy structures represent one of the undesired, irregular morphologies at low cathodic overpotential. Scanning electron microscopy observations showed that mossy structures formed transiently from layer-like morphology followed by the formation of protrusions with a size of submicrometers. These protrusions still exhibited layer-like features in the initial stage. In addition to this transition behavior, the propagation of mossy structures was monitored in situ by optical microscopy. At -5.0 mA cm(-2), mossy structures formed successively and propagated, while there was no clear change in layer-like morphology during deposition outside these characteristic structures. At -20 mA cm(-2), the layer-like growth proceeded for longer duration and the population of the mossy structures apparently decreased. However, they continuously increased in size followed by successive formation of mossy structures once initiated. From these results, growth mode of zinc at low cathodic overpotential transiently changed from layer-like growth to mossy structure evolution accompanied with dynamic variations in local current density. (c) 2016 Elsevier Ltd. All rights reserved.

We report the fabrication and evaluation of the Cu/Bi bilayer absorber with electrodeposition. We designed the Cu/Bi absorber to satisfy the requirements for scanning transmission electron microscope (STEM). The residual resistivity ratios of films of Cu and Bi with electrodeposition was and , respectively; these values are sufficient for the requirements of STEM. We found that the Cu/Bi bilayer absorber TES microcalorimeter experienced a pulse-shape variation and we considered that these variations were caused by the quality of the contact surface between the absorber and TES. In addition, we examined the structure of the absorber using focus ion beam analysis and STEM. The results suggest that an oxidation between the Cu and seed layer, in which the layer is an electrode for electrodeposition, yielded variations. Moreover, thermal simulation suggests that the thermal conduction between the absorber and TES caused variations. The results of this study will improve the process of Bi electrodeposition.

We present a novel optical device for the analysis of chemical surface properties utilizing surface-enhanced Raman scattering. The device, a transmission-type plasmonic sensor (TPS), offers the advantages of high sensitivity, nondestructive sample characterization, simple setup, and low-cost fabrication. The TPS is composed of Ag nanoparticles (NPs) deposited on a convex quartz glass substrate. The enhanced Raman spectrum is acquired by focusing a laser beam perpendicular to the sample surface through the substrate. The laser beam generates plasmon polarization in droplet-shaped Ag NPs at the sensor/sample interface. Our results indicate the potential of the device as a versatile surface-analytical tool.

We have fabricated Co-Pt nanodot arrays by combining electrodeposition with electron beam lithography (EBL) for applications in ultra-high density magnetic recording media, such as bit-patterned media (BPM). In this work, we analyzed the initial nucleation and growth of Co-Pt inside nanopores to achieve nanodot arrays with high deposition uniformity, as well as magnetic properties. At -900 mV (vs. Ag/AgCl), multiple nuclei of 2.0-3.0 nm in size were randomly distributed, even in nanopores with a 10 nm diameter, which could result in a lack of uniformity in the magnetic properties. The number of nuclei was then reduced by applying a less negative potential (>-700 mV vs. Ag/AgCl) to deposit a single nucleus inside each nanopore. As a result, a single grain of 5.0-10 nm in size was successfully deposited inside the nanopore, which could induce uniform magnetic properties in each nanodot. In addition, at less negative potentials, the coercivity of the Co-Pt films increased, which was induced by the epitaxial-like growth of Co-Pt from the Ru substrate. Cross-sectional TEM analysis suggested that Co-Pt deposited with a less negative potential was single crystalline with uniform hcp lattice fringes in the direction perpendicular to the Ru interface, indicating the formation of highly uniform nanodot arrays with high perpendicular magnetic anisotropy. (C) 2015 Elsevier Ltd. All rights reserved.

ラマン散乱分光法は非破壊で動的な化学構造の変化を測定することができる．また高速での測定も可能なのでさまざまな外部入力と同時に測定することもできる．本報告では，摺動時の摩擦力などの機械物性とラマンスペクトルを高速で同時測定を行った結果を紹介する．

In this study, we construct composite structures of CoPt multilayer alloy nanowires by electrodeposition using a polycarbonate template membrane (PT). The holes in PT are subsequently filled with CoPt multilayer alloy films to form nanowires. The composition of the films can be controlled by modifying the potential to produce high anisotropy CoPt alloy multilayer nanowires. The CoPt multilayer nanowires have a periodic structure like bamboo with a chemical composition of (Co80Pt20/Co30Pt70)n. Polycrystalline and ferromagnetic characteristics were visible in a single layer of Co80Pt20 nanowire. A vertical 3D magnetic domain wall memory has a ferromagnetic bit layer and a domain wall layer. Thus (Co80Pt20/Co30Pt70)n multilayer nanowires can be used in domain wall controlled 3D memory devices like racetrack memory.

ラマン分光法は、高分解能で化学構造を分析する方法として優れているが、これに高速での動的観察機能を開発して動的機械物性と化学構造の同時観察を試みている。今回は、トライボロジー現象を例に摺動時の摩擦力と化学構造の変化について報告する。

<p>New technique for analyzing buried interface has developed based on surface-enhanced Raman scattering spectroscopy. It consists of plasmonic sensors and spectrometer equipped with high precision mechanisms. Performance of the system involves in-situ measurement of interfaces, i.e. liquid/solid or solid/solid, with high sensitivity and high depth resolution on a variety of samples. Additional functions are in-situ temperature measurement by anti-Stokes/Stokes ratio, simultaneous acquisition with laser heating, time-resolved measurement, and pulsed laser Raman spectroscopy. A depth profile of layered ultra-thin films, i.e. diamond-like carbon (DLC) or highly oriented pyrolytic graphite (HOPG), was analyzed in atomic scale resolution at solid/solid interface. Molecular configuration and bonding feature of liquid organic molecules, i.e. lubricants for magnetic disks or reducing agents for a plating, were analyzed at liquid/solid interface. Oxidation process or decomposition process of ultra-thin DLC films was analyzed for a variety of DLC films. Spectral change with irradiation time by pulsed laser heating exhibited a kinetic change of molecular structures in a chemical reaction with in-situ heating temperature measurement.</p>

Toward an establishment of a new production method of solar cell substrates, electrodeposition of Si was investigated in molten KF-KCl (eutectic composition, 45:55 mol%) after the introduction of SiCl4. Gaseous SiCl4 was directly introduced into the molten salt at 1023 K by a vapor transport method using Ar carrier gas. The dissolution ratio of SiCl4 exceeded 80% even with the use of a simple tube for the bubbling. Galvanostatic electrolysis was conducted at 923 K on a Ag substrate at 155 mA cm(-2) for 20 min in molten KF-KCl after the dissolution of 2.30 mol% SiCl4. Although compact Si layer was formed, the smoothness was lower compared to that obtained from the melt after the addition of K2SiF6. The anionic molar fraction is probably one of the factors affecting the morphology of deposit.

Electrolytic production process for solar-grade Si utilizing liquid Si-Zn alloy cathode in molten CaCl2 has been proposed. Toward the establishment of the process, the behavior of liquid Zn metal was investigated in molten CaCl2 at 1123 K. The evaporation of Zn metal was largely suppressed by an immersion into molten salt, which enables the use of Zn electrode in spite of the high vapor pressure of Zn. The cyclic voltammetry suggested the reduction of SiO2 at 1.45 V vs. Ca2+/Ca on a Zn cathode. After the potentiostatic electrolysis at 0.9 V, Si particles with diameters of 2-30 mu m were precipitated in the solidified Zn matrix by the slow cooling process of the produced liquid Si-Zn alloy. The alloying rate between solid Si and liquid Zn was measured as 4.56 mu m s(-1), and it linearly decreased with the Si content in liquid Zn phase.

© Copyright 2016 by ASME.A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580°C and 366°C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250μs at the heating temperature of 580°C. The result shows no damage can be estimated in DLC films for HAMR because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.

© Copyright 2016 by ASME.A chemical depth profile in lubricant films, carbon films, and their interfaces is an informative parameter for hard disk media because molecular features of lubricants bonded to a surface of carbon overcoats (COCs), which usually consist of a nitrogen doped layer, are important to achieve high tribological performance. However, it was difficult to analyze their interfaces with high depth resolution because thickness of lubricant films and COC films are so thin, i.e. 1.5nm and 2nm, respectively. We have developed new method using plasmonic sensors, which has measurement capability for chemical structures with depth resolution of 0.1nm by surface-enhanced Raman spectroscopy (SERS). We examined the lubricant film composed of perfluorinated polyether (PFPE) with phosphazene derivative (A2OH) on a diamond-like carbon (DLC) film. The result shows that the functional group is adsorbed on the DLC surface, where lower shift in the wave number of phenyl group is observed. The depth profile of the intensity ratio of D-peak to G-peak shows the maximum at around the surface of the DLC film. A variety of organic components in the DLC films, fabricated by a chemical vapor deposition (CVD), were observed in it. Besides, the depth profiles shows that organic materials, involving methyl, ethyl, or ethylene groups, Co(OH)x exist in the film.

To elucidate the catalytic reaction mechanism of BH₄^－ (a reducing agent) on metal surfaces during electroless deposition, its oxidation reaction was investigated theoretically using density functional theory (DFT) calculation. Particularly in this study, dehydrogenation reaction of BH₄^－ was modeled and analyzed because it is the most important elementary step of overall oxidation for the catalytic behavior of metal surfaces. To ascertain the tendencies of catalytic activity of metal surfaces, the reaction on Cu(111) and that on Pd(111) were compared. Actually, Cu shows little catalytic activity toward BH₄^－ oxidation, whereas Pd shows strong catalytic activity. Results of reaction energy calculations show that the BH₄^－ dehydrogenation occurs with difficulty on Cu(111), but it occurs easily on Pd(111), which corresponds to experimental results. Detailed analyses of reaction system electronic structures show that the d-band states of each surface are important to assess the background of the difference. Because the Pd surface has a high-energy d-band, it can interact with high-energy unoccupied orbitals of BH₄^－, leading to electron donation from the surface toward BH₄^－. This electron donation effect from Pd provides dissociation activity of the B-H bond, which promotes dehydrogenation of BH₄^－.

The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

A new approach to produce high purity solar grade silicon (SOG-Si) using wet-chemical and electrochemical processes was proposed. First, diatomaceous earth was used as a source of silica and wet-chemical purification by acid leaching and solvent extraction processes were applied for eliminating heavy metal and light element such as boron, respectively. In particular, the solvent extraction using channel flow reactor demonstrated extremely high efficiency for eliminating boron to 7N (99.99999%) level purity. Secondly, the high-purity silica was reduced to silicon by the direct electrolysis method using molten CaCl2 as an electrolyte and Si plate as cathode. We proposed the continuous electrolysis system by feeding silica granules to the Si cathode set at the bottom of the cell. It was confirmed that the reduction proceeded steadily to form crystalline Si with a sufficient reduction rate. We also attempted electrodeposition of Si films and have developed a process using KF-KCl + K2SiF6 molten salt, from which uniform layer of Si with a thickness larger than 100 mu m could be formed. (C) 2015 Elsevier Ltd. All rights reserved.

Electrochemical approaches for the fabrication of functional micro–nano structures and devices were comprehensively described primarily on the basis of the results obtained from previous studies conducted by the author's group with the aim of demonstrating the potential for achieving further precise controllability. First, a theoretical study was conducted for investigating the processes, mainly focusing upon electroless deposition to present an approach for analyzing its reaction mechanism from the molecular level. These approaches could be powerful tools for elucidating the overall process and could contribute toward achieving the precise design of processes. Second, some experimental approaches for achieving the precise control of micro–nano fabrication of functional structures, such as maskless and electroless fabrication of metal nano-patterns, lateral enhanced electrodeposition to form ultrathin layers, as well as the nanostructures for various devices by through-mask electrochemical deposition, were introduced to demonstrate high capability of the processes for nanoscale fabrication in various applications.

A new method for electroplating Si using a water-soluble KF-KCl molten salt electrolyte and high-purity gaseous SiCl4 has been proposed. To gain a fundamental understanding of the process, the electrodeposition of Si from Si(IV) complex ions on a Ag electrode in a molten KF-KCl-K2SiF6 system was investigated by cyclic voltammetry at 923 K. The reduction of Si(IV) ions to metallic Si was observed as a single 4-electron wave, which is explained by an EqEr (quasireversible-reversible electron transfer reactions) mechanism. The diffusion coefficient of the Si(IV) ions in the electrolyte was determined to be 3.2 x 10(-5) cm(2) s(-1) at 923 K by chronoamperometry. (C) 2015 The Electrochemical Society. All rights reserved.

A Pi-structured Bi-Te micro-thermoelectric device with a large upper electrode, i.e., an umbrella-type device, was fabricated via electrodeposition, and the effect of the size of the electrode was evaluated. The Bi-Te thermoelectric materials were electrodeposited from HNO3-based aqueous electrolyte. The device consisted of eight arrays, each consisting of 110 thermoelectric units, each of which was electrodeposited onto the patterned substrate with an array of 50 x 50 mu m(2) holes that were 20 mu m deep. The deposition conditions for the n-type and p-type Bi-Te films were optimized to enable patterned electrodeposition of the materials to yield dense and uniform deposits. Accordingly, the materials were selectively deposited in a pattern to fabricate the thermoelectric micro-device. The resultant umbrella-type device, whose electrode is 1.65 times larger than smaller electrode, generated 4.57 times more power than the device with a smaller electrode. Therefore, we confirmed the improvement power by using an umbrella-type device. (C) 2014 Elsevier Ltd. All rights reserved.

TiO2 nanotubes are widely investigated materials for photoelectrochemical water splitting, but the presence of trap states limits their performance by facilitating the recombination of electron/hole pairs. In this investigation we unequivocally demonstrate that the photocurrent improvement observed in TiO2 nanotubes after performing electrochemical doping with hydrogen or lithium ions is due to trap state passivation. Specifically, electrochemical impedance spectroscopy evidences that trap state defects disappear upon electrochemical doping, concurrent with an increase in the electron lifetime and faster photocurrent transients. This results in a two-fold enhancement in the photocurrent under simulated sunlight at 1.0 V vs. SCE. Li intercalation was confirmed and the structure as well as the composition of the modified nanotubes was elucidated by GDOES, XPS, and TEM.

The electrochemical reduction behavior of stratified SiO2 granules in molten CaCl2 at 1123 K (850 A degrees C) was investigated to develop a new process for producing solar-grade silicon. The cross sections of the electrolyzed electrode prepared from a graphite crucible filled with SiO2 granules were observed and analyzed. The visual and SEM observations indicate that the overall reduction proceeds via two different routes. In one route, the reduction proceeds along the granule surfaces from the SiO2 near the conductor to the distant SiO2. In the other route, the reduction proceeds from the granule surface to the core of each granule. The reduction along the granule surfaces is faster than that from the surface to the core. Fine SiO2 granules are expected to be favorable for a high reduction rate. (C) The Minerals, Metals & Materials Society and ASM International 2014

The kinetic characteristics of electrochemical reduction of SiO2 granules in molten CaCl2 were investigated to develop a new process for producing solar-grade silicon. The reduction rate was-evaluated based-on-the time dependence of the reduction fractions measured from the growth of the reduced Si layer and the weight change of the samples during electrolysis. The samples were prepared by potentiostatic electrolysis of SiO2 granules in molten CaCl2 at 1123 K. The results indicated that the reduction was fast at the initial stage of electrolysis, and gradually slowed as the reaction progressed. The apparent current density reached 0.7 A cm(-2) at the initial stage, which was comparable to the commercial Hall-Heroult process for aluminum production. (C) 2014 The Electrochemical Society. All rights reserved.

A novel approach toward the purification of silica and removal of boron impurities via solvent extraction with 2-ethyl-1,3-hexanediol using a microchannel device is presented. The microchannel, fabricated on Si substrates using lithographic techniques, had 100 mu m width, 100 mu m depth, and 10 mm length. Amorphous silica spiked with a trace amount of boric acid and refined diatomaceous earth used as silica feedstock were purified. Residual boron content was determined by inductively coupled argon plasma atomic emission spectrometry. Following extraction using a microchannel device, the residual boron content was less than 1.0 ppm for the former silica feedstock and than 2.5 ppm for the latter one, and the contact reaction period was 0.03 seconds for both type of silica feedstock. These are lower and significantly shorter due to much shorter diffusion distance and much larger specific interfacial area as compared to those observed when using a conventional separatory funnel, for both types of silica feedstock. Hence, it is suggested that microchannel devices can be utilized as an attractive approach toward the production of high-purity silica as a source for solar-grade silicon. (C) 2014 The Electrochemical Society. All rights reserved.

A NiP imprinting mold with patterns, whose size is from nanometer to submicrometer (170, 500, and 1000nm diameter), was fabricated by electroless deposition of NiP on a 3-aminopropyltriethoxysilane (APTES) modified master mold. The NiP deposit as a replicate mold was then detached from the master mold. The initial NiP deposition in patterns of the master mold was investigated
moreover, nanoindentation was successfully performed on a single NiP pattern for investigating the hardness. The NiP had a similar grain size in different sizes of patterns of the master mold during the initial deposition, as well as the same hardness of the NiP patterns (approximately 12 GPa) was observed. These results indicated that the initial NiP deposition and hardness of NiP were not size dependent above 170 nm. The surface morphology of the NiP detached from the master mold and NiP pattern of different sizes were investigated as well. © 2013 The Japan Society of Applied Physics.

電解析出法とリソグラフィによりhcp-Co_<80>-Pt_<20>及びL1_0-Fe-Ptの薄膜とナノドットアレイをhcp-Ru(002)/Si基板上に形成し,特性評価を行った.また,初期からの析出制御を目的に,印加電位及びドット径がCo-Ptの析出挙動に及ぼす影響を解析した.電子線描画法を用いたプロセスでは2Tb/in.^2に相当する18nm周期,10nm径のナノドットパターンが均一に形成されていることを確認した.初期析出過程の解析の結果,比較的貴な印加電位(-400mV,-500mV vs Ag/AgCl)では核成長が優先的に生じるため,Co-Ptの粒径が増大する傾向が確認され,印加電位及びドット径によりCo-Ptの粒径制御が可能であることが示唆された.Fe-Pt合金の特性評価の結果,膜厚10nmにおいて9.0kOe,また膜厚25nmにおいて9.8kOeの保磁力が得られ,初期段階からの保磁力の向上が示された.さらに,650℃でのアニール処理により膜厚10nmにおいてL1_0構造への相転移が確認された.UV-ナノインプリント法を用いたプロセスでは,35nm径,100nm周期のFe-Ptナノドットアレイが広範囲に形成されていることを確認した.

Oxidation of the reductants is a dominant factor in the electroless deposition process. In order to obtain fundamental knowledge about the reaction mechanism of reductant oxidation for more precise control of the solid-liquid interface in this process, we have attempted to characterize the behavior of reductants adsorbed on Cu surface by using plasmon antenna enhanced Raman scattering. The concentric-patterned antenna coated with Cu, which consisted of a dimple array with single hole or a single hole with coaxial dimples, was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmons. By using this antenna and comparing the spectra to the results of Density Functional Theory (DFT) calculations, Raman peaks of adsorbed reductants on Cu were identified. Furthermore, we examined the conformation of adsorbed reductants by DFT calculation of the adsorption model of reductants on fcc-Cu(111) surface. As a result, the nature of reductant adsorption on Cu surface has been investigated from a computational point of view and an experimental point of view, and such in-situ characterization will be useful for analysis of a variety of systems at solid-liquid interface. (c) The Electrochemical Society of Japan, All rights reserved.

An electroless NiP imprinting mold was fabricated through replication of a cyclo-olefin polymer (COP) master mold. The NiP was electrolessly deposited on a nanopatterned COP master mold, pretreated by ultraviolet (UV) irradiation prior to modification with 3-aminopropyltriethoxysilane (APTES). The NiP deposit as a "replicate" was then detached from the COP master mold. Additionally, by optimizing the UV irradiation period, APTES could be formed on the COP master mold for electroless deposition without disturbing the nanopattern geometry of the COP master mold. The water contact angle and surface morphology of the COP surface, and the adhesion strength between deposited NiP and the COP surface were investigated. © 2013 The Electrochemical Society of Japan, All rights reserved.

Direct electrolytic reduction of SiO2 was investigated in molten CaCl2 at 1123K as a fundamental study to develop a continuous process for solar-grade Si production. Several different types of SiO 2 granules, as well as SiO2 pellets, were successfully reduced to Si on the bottom cathode of a Si plate. Three parameters were varied in the reduction of SiO2 granules: electrode potential, layer thickness of the SiO2 granules, and SiO2 particle size. The reduction rate was evaluated by the magnitude of the reduction current. The main factor determining the reduction rate was the diffusion of O2- ions inside the reduced porous Si layer filled with the electrolyte. Another factor which influenced the reduction rate was the contact resistance between Si granules. © The Electrochemical Society of Japan 2013.

我々は,電気化学的手法である電解析出法とリソグラフィ技術を用いて,ビットパターンメディア(BPM)への応用を目的とした強磁性ナノドットアレイの形成を試みている.本研究では強磁性体としてhcp-Co-Pt(002)とL1_0-Fe-Ptに着目し,下地層としてhcp-Ru(002)層を用いることで,極薄膜での磁気特性向上を試みた.また,電子線描画法により形成したナノドットパターンに対して電解析出法によりCo-Pt及びFe-Ptを充填し,強磁性ナノドットアレイの形成及び初期析出過程の解析を試みた.その結果Ru下地層を用いることで,形成されたCo-Pt薄膜の保磁力向上,結晶性向上が確認された.電子線描画法を用いたプロセスでは2Tb/in.^2に相当する18nm周期,10nm径のCo-Ptナノドットアレイの形成を確認した.初期析出解析を行なった結果,印加電位によりナノドット内におけるCo-Ptの粒径が制御可能であることが示された.Fe-Ptに関しては,アニール処理によりL1_0構造への相転移が確認され,保磁力の向上が示された.

The electrodeposition of silicon from silicon tetrachloride in the hydrophobic room temperature ionic liquid trimethyl-n-hexyl ammonium bis-(trifluoromethylsulfonyl) imide was investigated by cyclic voltammetry and chronoamperometry. In situ electrochemical quartz crystal microbalance (EQCM) impedance spectroscopy was used to estimate the mass of films during deposition. The charge efficiency estimated from EQCM measurements is similar to 190-250% for four-electron silicon reduction. However, compositional analysis by XPS shows that the EQCM current efficiency estimates are artificially high due to ionic liquid inclusion in the films. Taking the mass concentration of impurities into account, the bestcase estimate of current efficiency is found to be approximately 130% for constant potential deposition, suggesting silicon may not have been completely reduced at the potentials investigated, or a chemical reaction step occurs. We also consider that the EQCM analysis may include too many deviations from assumptions for accurate estimation of mass with the conditions studied. (C) 2012 Elsevier Ltd. All rights reserved.

The electrodeposition of silicon from silicon tetrachloride in the hydrophobic room temperature ionic liquid trimethyl-n-hexyl ammonium bis-(trifluoromethylsulfonyl) imide was investigated by cyclic voltammetry and chronoamperometry. In situ electrochemical quartz crystal microbalance (EQCM) impedance spectroscopy was used to estimate the mass of films during deposition. The charge efficiency estimated from EQCM measurements is similar to 190-250% for four-electron silicon reduction. However, compositional analysis by XPS shows that the EQCM current efficiency estimates are artificially high due to ionic liquid inclusion in the films. Taking the mass concentration of impurities into account, the bestcase estimate of current efficiency is found to be approximately 130% for constant potential deposition, suggesting silicon may not have been completely reduced at the potentials investigated, or a chemical reaction step occurs. We also consider that the EQCM analysis may include too many deviations from assumptions for accurate estimation of mass with the conditions studied. (C) 2012 Elsevier Ltd. All rights reserved.

This paper described characterization of hydrazine adsorption on Cu surface with high-selectivity of component at right angle down to single molecular level using a plasmonic antenna enhancing Raman scattering. The antenna deposited by Cu with concentric pattern was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmon. By using this antenna, Raman peaks of adsorbed hydrazine on Cu was provided at 385 cm(-1). Furthermore, these peaks were only observed at 1-2 nm from the antenna surface which meant that this approach had a potential to define the structure of adsorbed hydrazine just only on the plasmon antenna. The structure of adsorbed hydrazine was gauche-conformation. This data corresponded to the Density Functional Theory (DFT) of adsorption model of hydrazine on fcc-Cu (1 1 1) surface. These results suggest that this method creates a wide range of spin-off effects to the characterization of solid-liquid interface. (c) 2012 Elsevier Ltd. All rights reserved.

The TiO2 nanotube system exhibits properties of interest in photoelectrochemical water splitting for hydrogen production, including high surface area and vectorial charge transport along the nanotube length. Changes in the anodizing electrolyte chemistry provide the means to control nanotube morphology as well as their length and width. Despite the large amount of work available on nanotube synthesis, however, a thorough assessment of the effect of anodization conditions on the photoelectrochemical performance is still unavailable. In this paper, we characterize TiO2 nanotubes produced by varying the water content of the organic anodization electrolyte and investigate the influence of the electrolyte on their photoelectrochemical performance. We find that the photocurrent efficiency of the nanotubes is optimized by using an 11 vol % water:ethylene glycol ratio. We also demonstrate that a double-anodization technique produces a cleaner surface, resulting in higher photon-to-current conversion efficiencies of up to 30% at 350 nm. Raman spectroscopy, X-ray diffraction, and electrochemical impedance studies support the notion that the variation in crystallinity as a function of water content is the main factor in determining the photocurrent efficiency of the nanotube system.

We demonstrated fabrication of nanogap electrodes with flat and thin Au films by using laterally enhanced growth of Au electrodeposition and applied the electrodes for electrical measurement of poly(3-methylthiophene) (P3MT) nanowires. The Au electrodeposition was performed on nnicrogap electrodes following an organic modification process on an insulator surface of the microgap electrodes. Then, P3MT nanowires were aligned between the nanogap electrodes for transistor property measurement. The result suggested that the fabricated nanogap electrodes were suitable to apply for electrical properties measurement of such organic nanowires because of small difference in height between top of the electrodes and the insulator surface. (C) The Electrochemical Society of Japan, All rights reserved.

Mechanical stress was applied to a Si single crystal wafer to evaluate the changes in its surface properties arising from the lattice strain induced by mechanical stress. The stress was applied quantitatively to the wafer in order to investigate the correlation between the degree of strain and the electrochemical properties of its surface. Finite element method (FEM) structural analysis was used to estimate the degree of strain on the surface, and the open circuit potential was measured in order to investigate the surface electrochemical properties. The analysis suggested that the surface of the wafer was under tensile strain, and the open circuit potential shifted toward the negative direction with the strain. This indicates that mechanical stress applied to a Si surface can change its electronic properties by changing the surface crystal structure. (C) 2012 Elsevier B.V. All rights reserved.

A nanoimprint lithography mold was fabricated through electroless deposition combined with self-assembled monolayer (SAM) modification. To copy nanopatterns as "replicates", NiP was electrolessly deposited on a nanopatterned master mold (made of SiO2/Si), whose surface was modified with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS). NiP deposits were then manually detached from the mold. SAM improves Pd catalyst coverage for electroless deposition, further improving the morphology of the electroless deposition of NiP on the nanopatterned master mold and controlling the adhesion strength between electroless deposited NiP and the nanopatterned master mold to a level appropriate for smooth detachment. The initial catalyzation process and mechanical properties (such as, the hardness and adhesion strength of the SiO2 substrate) of electroless deposited NiP were also systematically investigated. (c) 2012 Elsevier Ltd. All rights reserved.

Mechanical stress was applied to a Si single crystal wafer to evaluate the changes in its surface properties arising from the lattice strain induced by mechanical stress. The stress was applied quantitatively to the wafer in order to investigate the correlation between the degree of strain and the electrochemical properties of its surface. Finite element method (FEM) structural analysis was used to estimate the degree of strain on the surface, and the open circuit potential was measured in order to investigate the surface electrochemical properties. The analysis suggested that the surface of the wafer was under tensile strain, and the open circuit potential shifted toward the negative direction with the strain. This indicates that mechanical stress applied to a Si surface can change its electronic properties by changing the surface crystal structure. (C) 2012 Elsevier B.V. All rights reserved.

A nanoimprint lithography mold was fabricated through electroless deposition combined with self-assembled monolayer (SAM) modification. To copy nanopatterns as "replicates", NiP was electrolessly deposited on a nanopatterned master mold (made of SiO2/Si), whose surface was modified with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS). NiP deposits were then manually detached from the mold. SAM improves Pd catalyst coverage for electroless deposition, further improving the morphology of the electroless deposition of NiP on the nanopatterned master mold and controlling the adhesion strength between electroless deposited NiP and the nanopatterned master mold to a level appropriate for smooth detachment. The initial catalyzation process and mechanical properties (such as, the hardness and adhesion strength of the SiO2 substrate) of electroless deposited NiP were also systematically investigated. (c) 2012 Elsevier Ltd. All rights reserved.

4Tb/in2以上の記録密度に対応する極薄潤滑膜/DLC保護膜の化学構造を、プラズモンセンサと表面増強ラマン散乱分光法で測定することに成功した。また膜の深さ方向の化学構造変化も0.1mmの分解能で測定した。

We investigated the laterally enhanced growth of electrodeposited Au for fabricating nanogap electrodes. To enhance the lateral growth, we carried out electrodeposition over patterned electrodes onto a SiO2 surface modified with self-assembled monolayers (SAMs) or dendrimers with amine groups. The morphology and thickness of the Au films were controlled by adjusting deposition conditions such as duration, applied potential, and Au ion concentration in the bath. To investigate the mechanism of the laterally enhanced growth, the surface states of SAM- or dendrimer-modified SiO2 were analyzed by X-ray photoelectron spectroscopy (XPS). The XPS results indicate the existence of organic molecules and Au ions on the SiO2 surface, which suggests that laterally enhanced growth is induced by the Au ions coordinated on the amine groups of the organic molecules. To further analyze the mechanism of the laterally enhanced growth, we investigated the relationship between the morphology of the laterally enhanced growth of Au and the amount of Au ions on organic molecules. The laterally enhanced growth of Au is expected to be useful for fabricating thin film nanogap electrodes. (C) 2012 Elsevier Ltd. All rights reserved.

The influence of water molecules on the reaction behavior of hypophosphite ion, which acts as a reducing agent for electroless deposition, on metal surfaces was elucidated by calculating the adsorption structure of hydrated hypophosphite ion on a Pd surface using Monte-Carlo simulation and density functional theory calculations. Through geometrical optimization, the most favorable structure of the hydrated hypophosphite ion was obtained, in which six water molecules interact with the oxygen of hypophosphite ion and no water interacts with the hydrogen of hypophosphite ion. Further calculations indicated that the hydrated hypophosphite ion adsorbed on the Pd surface via hydrogen. (C) The Electrochemical Society of Japan, All rights reserved.

To elucidate the mechanism of catalytic activity of metal surfaces on the reaction of hypophosphite ions, which act as a reducing agent for electroless deposition, molecular orbital interactions between hypophosphite ions and metal surfaces were analyzed using density functional theory. Pd (111) and Cu (111) were chosen as the surfaces with high and low catalytic activity, respectively. The electronic states of adsorption systems were analyzed using the Mulliken population analysis. The position of the d-band plays a key role in determining the catalytic activity on P-H bond cleavage of hypophosphite. The Pd surface has a d-band near the Fermi level and contains a vacancy; this enables the donation and back-donation effect to occur on the adsorbed hypophosphite and promotes P-H bond cleavage. On the other hand, the Cu surface has a d-band in the deep energy area and contains no vacancy; the donation and back-donation effect is not induced and P-H bond cleavage is not promoted. This difference in the degree of promotion of P-H cleavage is responsible for the difference in the catalytic activity on P-H cleavage and dehydrogenation of hypophosphite ions, which in turn explains the difference in the catalytic activity during the entire hypophosphite oxidation process. (C) The Electrochemical Society of Japan, All rights reserved.

An electroless deposition process for fabricating CoNiP nanodot arrays (less than 50 nm in height) with high magnetic coercivities was investigated. To fabricate such nanostructures, we improved the crystallinity of the CoNiP deposits in the initial deposition stage by applying an fcc-Cu(1 1 1) underlayer with low lattice mismatch to hcp-Co(0 0 0 2), and an autocatalytic electroless deposition process at the Cu surface was carried out by using dual reducing agents, H(2)PO(2)(-) and N(2)H(4). CoNiP films demonstrated high perpendicular magnetic coercivities in the initial deposition stage since the highly crystalline hcp(0 0 0 2) CoNiP layers were grown parallel to the Cu underlayers. Nanopatterned substrates were formed by UV-nanoimprint lithography. CoNiP was electroless deposited on the nanopatterned substrates. As a result. CoNiP was deposited selectively from the bottom of the nanopores with few defects in a large area. Perpendicular coercivities higher than 3000 Oe were obtained for nanodots even with heights of 50 nm. Thus, an electroless deposition process that can be used to form nanostructures with high crystallinities in the initial stage without any anomalous deposition was demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.

Ultra-thin DLC films and lubricant films are requested for high density magnetic recording. It was difficult for Raman spectroscopy to measure their molecular structures because of its low sensitivity. Newly-developed plasmonic sensor successfully acquired Raman spectrum of DLC films or lubricant/DLC interfaces with sub-nanometer thickness. Crystal structure of ultra-thin DLC films were slightly changed compared with that of thick films. Specifically, a graphite-like structure increases with decreasing thickness. It was found that organic and inorganic contaminations exist on a magnetic layer or a magnetic layer/DLC interface. According to the Raman spectrum analysis, a feature of adsorbed lubricant molecules of lubricant on the DLC film was confirmed.

We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL) Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness As a result we obtained CoPt nanodot arrays with 150-nm diameter 300-nm pitches and 20-nm heights which have uniform structures on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk The perpendicular coercivity of the CoPt nanodot arrays was as high as 5 4 kOe From these results we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity (C) 2010 Elsevier Ltd All rights reserved

We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL) Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness As a result we obtained CoPt nanodot arrays with 150-nm diameter 300-nm pitches and 20-nm heights which have uniform structures on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk The perpendicular coercivity of the CoPt nanodot arrays was as high as 5 4 kOe From these results we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity (C) 2010 Elsevier Ltd All rights reserved

An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h(+)) was involved in the etching reaction and the collection of the h(+) was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition. (C) 2010 Elsevier B.V. All rights reserved.

Discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied as routes to achieve higher density hard disk drives. In the DTM and BPM, it is essential to isolate the data tracks or bits with non-magnetic materials to reduce the magnetic noise from adjacent tracks or bits. In contrast to the conventional procedure of physically etching the media, we attempted to isolate the tracks or bits with soft regions using an area-selective ion irradiation method. We prepared hard and soft nano-composite structures by nanoimprinting, followed by ion irradiation. In this study, we confirmed the magnetic reversal process of the hard and soft regions of the nano-composite structure using magnetic force microscopy (MFM) with various external applied magnetic fields. The analysis of the magnetization reversal process of patterned Coupled Granular Continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

Synchrotron radiation-induced total reflection X-ray fluorescence (SR-TXRF) analysis is a high sensitive analytical technique that offers limits of detection in the femtogram range for most elements. Besides the analytical aspect, SR-TXRF is mainly used in combination with angle-dependent measurements and/or X-ray absorption near-edge structure (XANES) spectroscopy to gain additional information about the investigated sample. In this article, we briefly discuss the fundamentals of SR-TXRF and follow with several examples of recent research applying the above-mentioned combination of techniques to analytical problems arising from industrial applications and environmental research. (C) 2010 Elsevier Ltd. All rights reserved.

An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h(+)) was involved in the etching reaction and the collection of the h(+) was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition. (C) 2010 Elsevier B.V. All rights reserved.

This paper describes the fabrication process of CoPt nandot arrays on a glass disk substrate with a CoZrNb underlayer as a soft magnetic underlayer (SUL) by using an electrochemical process, and also the analysis on the magnetic properties of these fabricated CoPt nanodot arrays. We formed nano-patterned substrates by UV-nanoimprint lithography (UV-NIL) on the glass disk substrate. CoPt was electrodeposited into the nano-patterned substrates optimizing the electrodeposition condition and bath composition as well as a Cu intermediate layer. The construction of the nanodot arrays were CoPt nanodot arrays (20 nm)/Cu (5 nm)/CoZrNb (100 nm)/Cr (5 nm)/Glass disk. Magnetic signals were clearly observed on the dc magnetized state and multi domain were observed in each nanodot on the ac magnetized state by magnetic force microscopy (MFM). The perpendicular coercivity of the CoPt nanodot arrays was 430 kA/m. These results showed electrochemical process can be used for the manufacture of magnetic recording media.

The electrochemical behavior of Al-Si alloy films in zincate solution was investigated to elucidate the effects of zincate pretreatment on the Zn morphology and subsequent electroless NiP deposition, which is used for under bump metallization (UBM) in integrated circuit (IC) chip packaging. To investigate the electrochemical behavior of the Al-Si films during the zincate pretreatment, the immersion potential and the surface morphology during Zn and NiP deposition were evaluated using Al-Si electrodes that had been fabricated onto two types of Si substrates with different specific resistances. A heterogeneous point was observed for samples fabricated onto Si substrates with high specific resistance (45-95 Ωm), but no such point was observed on samples fabricated onto Si substrates with low specific resistance (0.00001-0.00002 Ωm). This result suggests that the morphology of the deposits was affected considerably by the specific resistance of the Si substrate.

Copper electrolysis is carried out in a stagnant 0.05 M CuSO4 aqueous electrolyte under alternating current (AC) condition. Transient mass transfer rate of Cu2+ ion caused by copper electrodeposition with AC is studied theoretically and experimentally with the holographic interferometer. The effect of buoyancy convection developing along the vertical plane electrodes on the transient concentration boundary layer (CBL) structure accompanying with AC is focused on. Two different electrode configurations, the horizontal cathode over anode and the vertical electrode settings, are employed for this purpose. The CBL thickness tends to increase over long duration time in the former configuration, while it converges to a steady-state value in the latter. Both calculated and measured concentration profiles in the vertical electrode configuration exhibit the characteristic transient behaviors composed of the pulsating CBL (PCBL) in the vicinity of the cathode surface and the stationary CBL (SCBL) outside the PCBL The appearance of the SCBL is ascribed to mass transfer by advection, and the overall CBL thickness depends on the hydrodynamic conditions such as the magnitude of buoyancy convection. (C) 2010 Elsevier Ltd. All rights reserved.

To increase the areal density of hard disk drives (HDDs), discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied. In the DTM and BPM, it is essential to isolate data tracks or bits. Unlike isolating the data tracks or bits using the conventional procedure involving physical etching, we attempted to isolate the tracks or bits with a soft guard band using an area-selective ion irradiation method. We prepared hard and soft (H/S) patterned films by nanoimprinting followed by ion irradiation. We confirmed the magnetic isolation of tracks and bits using magnetic force microscopy (MFM) images and magnetooptical Kerr effect (MOKE) signals. The results of an analysis of the magnetic properties of patterned coupled granular continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

We attempted to fabricate patterned media using the electrochemical deposition process along with nanopatterned substrates prepared by the electron beam lithography (EBL), UV nanoimprint lithography (UV-NIL), and spin-on-glass nanoimprint lithography (SOG-NIL) approaches. CoPt was electrodeposited into the nanopatterned substrates and chemical mechanical polishing was carried out to planarize the surface. It was clarified that CoPt nanodot arrays were successfully deposited into the patterned nanopores fabricated by UV-NIL and SOG-NIL as well as by EBL with high area selectivity and uniformity. The density of the CoPt nanodot arrays deposited into the nanopores fabricated by EBL was equal up to an areal recording density of 250 Gbit/in(2). (C) 2008 Elsevier B. V. All rights reserved.

We present fabrication methods of functional three-dimensional (3-D) micromesh structures coated with titanium dioxide (TiO(2)) microparticles and biocatalysts. The 3-D micromesh structures are useful for fabricating highly efficient microreactors because of their large surface area. In this study, TiO(2)-embedded SU-8 micromesh structures were formed by coating a TiO(2)/SU-8 mixture onto the surface of SU-8 micromesh structures. Biocatalyst-immobilized micromesh structures were also formed by coating a biocatalyst/photopolymer mixture onto SU-8 micromesh structures.

Microreactors and micro-fluidic devices require micro-tube structures to reserve and manipulate extremely small volume of liquid specimen, and nano-hole on the micro-tube is useful for its injection, aspiration and filtration, etc. In the present study, we attempted to develop a precise etching process to form nano-hole to the edge part of the micro glass tube by controlling SiO2 etching conditions with diluted aqueous HF solution. The arrayed micro-glass-tubes were fabricated by electrochemical etching of Si wafer followed by wet-thermal oxidation. The bottoms of arrayed micro-glass-tubes were exposed from Si wafer, which possessed pyramid-shape edges. The etching with optimized concentration of HF formed uniform nano-holes only at every bottom edge, indicating self-alignment of the etching process. The diameter of the nano-holes was controllable in the range of ca. 100-500 nm by adjusting the immersion duration and thickness of the glass tube. Nonlinear diffusion of fluoride species to the bottom edges could be the origin of the self-aligned formation of nano-holes at the bottom edges. (C) 2007 Elsevier Ltd. All rights reserved.

Nanoscale dot patterns of cobalt alloy were formed on a silicon substrate using the ultra-violet nanoimprint lithography (UV-NIL) technology in combination with an electrodeposition process. We developed an improved UV-NIL equipment that can evacuate the chamber during imprinting. Using this equipment, we successfully imprinted 240-nm dot patterns with 500 nm pitch on a photocurable resin with high dimensional accuracy. Thickness control of the resin and imprinting under vacuum are important issues to obtain fine nanopatterns. Using these resin patterns as a mask layer, 300-nm cobalt alloy patterns are successfully formed by the electrodeposition process. (c) 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The oxidation mechanism of hydrazine and hydroxylamine were investigated using molecular orbital (MO) calculation. Two pathways for their reactions were verified. One is initiated by hydrogen elimination from the reducing agent, followed by coordination of hydroxyl group to center nitrogen atom accompanied with electron emission. Another is initiated by coordination of hydroxyl group to hydrogen atom to form H2O, which is eliminated later, followed by electron emission. The calculated results indicated that the oxidation reactions of hydrazine preferentially proceeded via the second pathway. It was also indicated that only the first electron emission steps of the hydrazine oxidation took place on Cu surface, while the following reactions proceeded at near the solid/liquid interface. The oxidation of hydroxylamine also proceeded via the elimination reaction of H2O. After the oxidation, calculated heats of reactions suggested that OH radical, generated from N2O as a product, decomposed hydroxylamine.

The covalent attachment of alkyl groups to silicon surfaces, via carbon-silicon bond formation, has been attempted using gas-surface reactions starting from Cl-terminated Si(111) or H:Si(111) under ultraviolet light irradiation. The formation of Cl-terminated Si(111) and its resulting stability were examined prior to deposition of organic molecules. High-resolution electron energy loss spectroscopy (HREELS) was utilized for detecting surface-bound adsorbates. The detection of photo-deposited organic species on CI:Si(111) from gas-phase CH4 or CH2=CH2 was not significant. On H:Si(111), it was evident that after the photoreaction with gas-phase C2H5Cl, C2H5 groups were chemically bonded to the surface Si atoms through single covalent bonds. The C2H5 groups were thermally stable at temperatures below 600 K. Alkyl monolayers prepared on silicon surfaces by dry process will lead to a new prospective technology of nanoscale fabrication and biochemical applications. (c) 2006 Elsevier B.V. All rights reserved.

We succeeded in fabricating 256-pixel arrays of Ti/Au transition edge sensor (TES) microcalorimeters with electrodeposited microabsorbers made of Bi, and report on their test results. We confirmed till pixels tested so far were alive, however most of the microabsorbers were stripped off during cooling cycles. We investigated some pixels by irradiating with 5.9 keV X-rays, and confirmed that they actually worked as microcalorimeters. The X-ray pulses are represented by a sum of two components with different decay times. The ratio of the two components fluctuates from pulse to pulse, which limits the energy resolution to similar to 200 eV. We discuss the pulse shape of two decay-time components considering thermal conductivities, i.e., inside microabsorbers, between microabsorbers and TES. (c) 2005 Elsevier B.V. All rights reserved.

The oxidation mechanism of aldehydes, which are commonly used as reductants for an electroless deposition process, was studied by using Density Functional Theory (DFT) calculations. The reaction pathway of the three aldehydes, i.e., formaldehyde, acetaldehyde and glyoxylic acid, with different functional groups, were examined by calculating energy profiles of all intermediate species. It was indicated that the pathway in an isolated system proceeds via dianion-free intermediate species. Taking the solvation effect into consideration, it was indicated that the oxidation reactions of the three aldehydes preferably proceed at the solid/liquid interface. In combination with a Cu metal cluster as a model of metal surface, it was also indicated that the oxidation reactions proceed preferentially at the Cu surface. It was expected that the adsorption/desorption energy at the Cu surface of glyoxylic acid, which has an electron-accepting carboxyl group, was smaller and substituent effect lead to its high reducibility. (C) 2005 Elsevier Ltd. All rights reserved.

Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 mu m(2) in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the pattemed defects were also attempted. (C) 2005 Elsevier Ltd. All rights reserved.

Electrochemical behavior of At and At alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the At and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films. (C) 2005 Elsevier Ltd. All rights reserved.

Fabrication process for picoliter volume SiO2 glass tube array partially embedded in Si wafer was developed. As a template for the glass tubes, macropore array was formed at the surface of n-Si(1 0 0) wafer by photo-assisted electrochemical etching process. The area-selective formation of the array was achieved by applying Au/Cr micropatterns formed at the back-side surface of the substrate as the shade mask, which controls the illumination condition to optimize the etching reaction conditions. Subsequently, surface of the macropores was wet-thermally oxidized to form glass layer, and the bulk Si region was removed by alkaline etching, remaining the "glass tubes". As a result of complete removal of the bulk Si, released glass tubes were obtained. By partial removal of the bulk Si part, the glass tubes were exposed, fixed in the remaining Si substrate in the form of well-ordered array. It was confirmed that the depth, the exposed region and the wall thickness of each glass tube were controllable by adjusting the parameters such as the duration of the Si electrochemical etching, the alkaline etching and the wet-thermal oxidation, respectively. In order to demonstrate microreaction in the glass tube, aqueous rhodamine B solution was injected into the tubes and excitation light was irradiated to them. As a result, the fluorescence of rhodamine B was clearly detected, confirming the applicability of the glass tubes for various kinds of devices and systems such as microreactors. (C) 2005 Elsevier Ltd. All rights reserved.

To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

Pd cluster seeds for a double-layered perpendicular magnetic recording medium composed of a Co/Pd multilayered film and a CoZrNb soft magnetic underlayer (SUL) were fabricated with an electrochemical treatment. By immersing the SUL into an aqueous PdCl2 solution, the substitution of Pd for Co at the surface of the SUL took place, which was caused by the difference in electrochemical redox potential between Pd and Co. Uniformly distributed Pd clusters with 8 nm in diameter were successfully formed with the treatment for the optimized duration. Use of the Pd clusters as the seeds for deposition of the Co/Pd multilayered film increased the perpendicular coercivity and reduced the size of magnetic cluster of the film. These results suggested that the Pd cluster seeds led to the formation of magnetically isolated Co/Pd multilayered grains, improving the magnetic properties of Co/Pd multilayered film.

Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

The oxidation mechanism of TiCl3 as a reductant for an electroless deposition process was studied by ab initio molecular orbital method. The reaction process of TiCl3 proceeds with the substitution of Cl- to OH-. Net charge and spin density of the reactant, product, and intermediates were evaluated. It was suggested that the electron emission of TiCl3, which is originated by the oxidation of Ti(III) to Ti(IV), took place when Cl is replaced by OH- to form Ti(OH)(4). The catalytic activity of the metal surface, which is one of the most important factors for the electroless deposition process, was studied using a Pd-4 Cluster as a model surface. It was suggested that the Pd-4 cluster enhanced the reaction of TiCl3 to emit the electron. The effect of solvation is also taken into account in terms of the dielectric field constant. It was indicated that the heat of oxidation reaction shifted to an exothermic reaction with decreasing dielectric constant, indicating that the reaction preferentially proceeds in the vicinity of solid/liquid interface. However, it was indicated that the reaction could proceed in the bulk solution, suggesting that appropriate stabilization such as formation of complex is required for the application of the TiCl3 to the electroless deposition process.

Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

The oxidation mechanism of dimethylamine borane (DMAB), which acts as a reductant in the electroless deposition process, was studied using ab initio molecular orbital approaches such as Hartree-Fock (HF) and second order Møller-Plesset (MP2) calculations. The overall oxidation process of the DMAB was divided into each elementary reaction in which OH- substitutes H one by one and eventually forms B(OH)4-. The oxidation mechanism of DMAB in the isolated state, which was previously proposed by us, was refined using more accurate basis sets, and the effects of solvation and interaction with metal surface sites on the oxidation mechanism were also studied. Taking the solvation effect into consideration using the self-consistent reaction field method with an isodensity polarized continuum model (SCRF-IPCM), the heat of oxidation was transferred to an exothermic reaction with decreasing dielectric constant. This indicated that the reaction preferably proceeds at the solid|liquid interface. Combined with Cu(111) and Pd(111) neutral cluster models as metal surface sites, it was found that the oxidation reaction proceeds preferentially at the metal surface sites. It was also suggested that the catalytic activity of the deposited metal is caused by its electron acceptivity. © 2003 Elsevier Science B.V. All rights reserved.

As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

Attempt was made to develop novel maskless and electroless fabrication process of metal nanostructures by controlling local surface activity for the deposition reaction at silicon wafer surfaces. P-Si(100) wafers were cleaned to obtain hydrogen-terminated surface and nanoscopic patterns were formed on the surface by nanoindentation technique using a scanning probe microscope (SPM) with a diamond probe. By controlling the parameters such as the indentation force (within the order of 1 - 10 muN), nanoscopic patterns with different degrees of defects were formed. The scanning surface potential microscopy (SPoM) analysis clarified that these sites locally possessed negative shift in potential, i.e., higher activity for the reductive deposition of metal ions, which increased with an increase in the degree of defect. In order to achieve spontaneous (electroless) and selective deposition at those patterns, conditions of the solution were optimized and the formation of metal nanostructures, such as Cu nanodot arrays and wires, has been achieved. Capability of the present process to form nanostructures whose feature size is as small as 50 nm was demonstrated. (C) 2003 Elsevier Ltd. All rights reserved.

Signal and noise characteristics of Co/Pd multilayer perpendicular magnetic recording media are discussed based upon MFM analysis. The noise of the Co/Pd multilayer media is originated mainly from irregularities in the magnetic transition regions, and can be drastically suppressed by increasing the thickness of the carbon underlayer although a large number of reversed magnetic domains between the magnetic transitions still exist. The fine magnetic clusters formed in the medium with a thick carbon underlayer result in clear magnetic transition boundaries of recorded bits in the high recording density region. By examining the profile of the M-H loops. the decrement in the x value, which is defined as the slope of M-H loop at the value of coercivity, improves the signal to noise (S/N) ratio for the Co/Pd multilayer media. (C) 2001 Elsevier Science B.V. All rights reserved.

Molecular orbital study was applied to investigate electroless deposition processes, focusing upon reducibility of reductants as well as the effect of catalytic activity of the metal surfaces. Elementary reaction pathways of the reductants such as dimethylamine borane, hypophosphite ion, formaldehyde, and titanium trichloride were quantitatively examined in terms of the heat of reaction. It was indicated that the reaction via 5-coordinate intermediates was favorable for these species and that the value could be used for quantitative evaluation of the reducibility of the reductant species. The analysis of solvation effect on the reactions suggested that the reactions preferably proceed at the interfacial region, i.e. the surface of the metal, rather than in the 'bulk' solution region. The effect of catalytic activity of metal surfaces was investigated using a cluster-model surface. It was suggested that the elementary reactions were stabilized on the metal surfaces to enhance the electron emission from the reductants. On the other hand, difference in the stabilization effects for the reaction of hypophosphite ion was obtained due to the variation in the metal species, it was expected that the copper surface is not catalytically active for the reaction, which corresponds to the experimentally known results. (C) 2001 Elsevier Science Ltd. All rights reserved.

The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled stale, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties. (C) 2000 The Electrochemical Society. S0013-4651(00)02-081-4. All rights reserved.

The substrate (Ni)-catalyzed electroless gold plating process invented by Iacovangelo and Zarnoch has been investigated for plating gold on electroless nickel substrates for application to bonding of electronic devices. The process was found to yield uniform and adherent gold films on Ni-B substrates, whereas on Ni-P substrates acceptable gold films were obtained only when the P content was low and a pretreatment procedure was introduced to prevent the formation of surface oxide or to remove it completely. Unlike the conventional galvanic displacement process, the substrate-catalyzed process does not attack the nickel substrates and yields gold films with a very low porosity. Compared with autocatalytic electroless gold plating baths, the substrate-catalyzed bath is inherently more stable, although the maximum gold thickness obtainable is naturally limited. Results of these evaluations are presented in detail. (C) 2000 The Electrochemical Society. S0013-4651(99)106-062-0. All rights reserved.

Gradient control of magnetic properties in electroless-deposited CoNiP films was attempted and microstructural origin of the graded properties was investigated. Control of the single and dual gradient in magnetic properties, such as coercivity, Hc, in the direction of the film thickness was achieved by controlling the rotational speed of substrates during the deposition. The results of cross-sectional scanning electron microscopy and transmission electron microscopy investigations clarified that the size of the crystallites changed according to the speed of the rotation, forming the `graded' microstructure in the film thickness direction, which resulted in the graded properties.

Gradient control of magnetic properties in electroless-deposited CoNiP films was attempted and microstructural origin of the graded properties ties was investigated. Control of the single and dual gradient in magnetic properties, such as coercivity, Hc, in the direction of the film thickness was achieved by controlling the rotational speed or substrates during the deposition. The results of cross-sectional scanning electron microscopy and transmission electron microscopy investigations clarified that the size of the crystalites changed according to the speed of the rotation, forming the "graded" microstructure in the film thickness direction, which resulted in the graded properties. (C) 2000 The Electrochemical Society. All rights reserved.

The mechanism of direct copper plating on nonconductive resin substrates was studied using high-resolution TEM, SEM and XPS. Substrates were catalyzed by Pd/Sn catalyst and subsequently immersed in alkaline solution containing either copper ions or sulfide ions before electroplating. After conversion in the alkaline solution containing copper ions, catalyst colloid particles formed clusters and crystallinity improved. Sulfide compounds, however, formed by conversion in alkaline solution containing sulfide ions. Both conversion techniques markedly promoted propagation in electroplating. The effect is explained by propagation in which improved palladium colloid crystallinity and palladium sulfide formed in conversion play a critical role in determining the propagation rate.

The read-write characteristics of a perpendicular/longitudinal composite medium prepared by sputtering were investigated. The composite medium exhibited a higher voltage than a perpendicular single-layered medium, although the noise of these media was almost the same. The noise of the composite medium increased slightly with the recording density, suggesting that it was affected by the longitudinal underlayer. However, the noise reduction effect of the composite medium was observed by comparing with the simple superposition of the noise of each single layered medium. As a result, it was found that the perpendicular/longitudinal composite medium exhibited a higher S/N value than the perpendicular single-layered medium.

The possibility of electrodeposition of soft gold from a thiosulfate-sulfite bath was explored for electronics applications. The bath does not contain cyanide, and it is operated at a near neutral pH and a mildly elevated temperature. The bath is stable, does not undergo spontaneous decomposition without the addition of any stabilizer, and yields gold deposits with a hardness sufficiently low for use as gold bumps on semiconductor devices. Factors affecting the hardness were investigated in detail. It is shown that the use of high concentrations of the complexing agents and/or the addition of thallium(I) ions decreases both hardness and sulfur content of the deposit. The lowest Vickers hardness values achieved were approximately 80 kg mm(-2) in the as-deposited state and 50 kg mm(-2) after annealing at 350 degrees C for 30 min in air. The relationship between hardness and microstructure of the deposit was also examined.

The recording characteristics of a composite medium with a longitudinal magnetization recording layer as a underlayer of a perpendicular magnetization recording layer were evaluated by using ring-type heads. The results suggest that the residual magnetization mode of the medium is a phase synchronization mode, which forms a horseshoe-shaped magnetization region composed of the strong perpendicular magnetization region of the perpendicular layer and the longitudinal magnetization region of the underlayer. The reproduced voltage of the medium is higher than that obtained by simple superposition of the outputs of the perpendicular top layer and the longitudinal under-layer, and the waveform of the medium shows an almost single-peaked pulse. The recording density response and peak shift characteristics are not restricted by the characteristics of the underlayer. The magnetization state of the medium can be controlled by the medium and head parameters, indicating the importance of optimizing these parameters.

高速銅電析による電解銅箔のピラミッド状析出表面モルフォロジーの制御因子のなかで添加剤である塩素イオン, およびにかわの効果に着目して詳細な検討を加えた。Cl^-50ppmおよびにかわ2ppmを添加した場合の標準浴条件において, 表層付近ほど柱状組織が明確に発達していることを確認した。この柱状組織形成において塩素イオンは促進作用, にかわは抑制作用があり, 〈110〉配向の結晶粒子が優先的に成長した結果である。成長面 (マット面) の観察から, にかわがピラミッド状析出の鋭角化および均一性向上に寄与していることが明らかとなった。

The peak shift characteristics of perpendicular-longitudinal composite media in combination with a ring-typehead were investigated. It was found that the composite media had excellent peak shift characteristics in the region where the underlayer-medium showed worse characteristics. In the case of the composite media, strong perpendicular magnetization of the perpendicular recording layer suppressed the unfavorable effect of the underlayer. The underlayer's magnetization had great influence on the peak shift characteristics of the composite media, especially in the higher recording region. It is suggested that the peak shift characteristics are mainly subject to the condition of perpendicular magnetic reversal formed in the composite media.

Effects of saturation flux density (Bs) of read/write head on the recording characteristics of perpendicular/longitudinal composite medium were investigated. It was found that the recording sensitivity was improved by applying the higher Bs head. In higher density region, the reproduced-voltage-enhancement was enlarged with high Bs head, however, at the higher MMF region, the read/write characteristics was worse because the head field penetration becomes broad. Therefore, it was necessary to optimize the medium parameters in account to the head parameter.

The growth morphologies of electrodeposited silver under potential control on an Au (111) surface from the solutions of 5mM AgNO₃/0.5M HNO₃ and 5mM KAg (CN)₂/0.5M KCN were investigated using Scanning Tunneling Microscopy (STM) in air. The silver films were deposited between 20mV and 100mV overpotential. From 5mM AgNO₃/0.5M HNO₃, silver was deposited like a single crystal along the gold substrate at 20mV overpotential. At 50mV overpotential large grains (300-500nm) were formed. Finally, at 100mV overpotential rough films were formed. From 5mM KAg (CN)₂/0.5M KCN, silver was deposited like a single crystal at 20mV overpotential, and between 50mV and 100mV, smaller grain deposition with 50-100nm particles were clearly deposited compared to the deposit from 5mM AgNO₃/0.5M HNO₃.

Effects of saturation flux density (Bs) of read/write head on the recording characteristics of perpendicular/longitudinal composite medium were investigated. It was found that the recording sensitivity was improved by applying the higher Bs head. In higher density region, the reproduced-voltage-enhancement was enlarged with high Bs head, however, at the higher MMF region, the read/write characteristics was worse because the head field penetration becomes broad. Therefore, it was necessary to optimize the medium parameters in account to the head parameter. © 1995 IEEE

The dendrite growth behavior of Li metal galvanostatically electrodeposited on Ni substrate in a LiClO(4)-propylene carbonate electrolyte solution was in situ observed by a laser scanning confocal microscope with a metallographic microscope. A Li dendrite precursor is stochastically evolved on Ni substrate probably through a solid electrolyte interphase layer produced by the surface chemical reaction between a reduced Li metal and an organic electrolyte. The measured length of randomly growing Li dendrite arms was statistically analyzed. The initiation period of the dendrite precursor becomes shorter with increasing current density and decreasing LiClO(4) concentration. Once it has been initiated, the ionic mass transfer rate starts to govern the growth process of the dendrite arm length, exceeding over the surface chemistry controlling step. The dendrite arm length averaged over the substrate surface grows linearly proportional to the square root of time. The lower the concentration of LiClO(4), the steeper the inclination of the line at 5 mA cm(-2), whereas the concentration dependence of inclination is not evident at 0.5 mA cm(-2). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3486468] All rights reserved.

The electrochemical anodization of silicon films in aqueous solutions containing hydrofluoric acid was investigated. The films were deposited onto fused quartz chips from poly-crystalline, phosphorous doped silicon using magnetron physical vapor deposition in argon plasma. X-ray diffraction from these films showed that the atomic structure of silicon was amorphous. Current-potential profiles of the films in hydrofluoric acid solutions showed a linear increase in current with increasing anodic potential, unlike the diffusion limited profiles obtained from arsenic-doped silicon (100) crystals. In order to form microstructures within selected regions of the silicon, an epoxy resin was lithographically patterned onto the surface of the silicon prior to anodization. Three-dimensional profiles of the film's surface after removal of the resin revealed that the regions of silicon protected by the resin had formed microstructures.

In order to elucidate the reactivity difference of hypophosphite ions used as reducing agents for electroless deposition on different metal surfaces, such as Pd and Cu, electronic structures of the activation states of hypophosphite ion oxidation on these surfaces were intensively analyzed by using Density Functional Theory (DFT). In the calculation, we focused on the dehydrogenation reaction which should be a rate-determining step in the elementary reaction steps. From the calculation results, a particular orbital interaction between the hypophosphite ion and the metal surface was observed. On Pd (111), the s-orbital of H in the hypophosphite ion interacts singly with the d- or p-orbital of Pd (111). This interaction induces an anti-bonding interaction between H and P in the hypophosphite ion, which is responsible for P-H cleavage. On the other hand, on Cu (111), the s-orbital of H and the s-orbital of P in a hypophosphite ion interact simultaneously with the p-orbital of Cu (111). This interaction barely induces an anti-bonding interaction between H and P in the hypophosphite ion. Such a difference in orbital interaction structures should be related to P-H cleavage activity and the reactivity difference of hypophosphite ion on each metal surface. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623782] All rights reserved.

In order to elucidate the reactivity difference of hypophosphite ions used as reducing agents for electroless deposition on different metal surfaces, such as Pd and Cu, electronic structures of the activation states of hypophosphite ion oxidation on these surfaces were intensively analyzed by using Density Functional Theory (DFT). In the calculation, we focused on the dehydrogenation reaction which should be a rate-determining step in the elementary reaction steps. From the calculation results, a particular orbital interaction between the hypophosphite ion and the metal surface was observed. On Pd (111), the s-orbital of H in the hypophosphite ion interacts singly with the d- or p-orbital of Pd (111). This interaction induces an anti-bonding interaction between H and P in the hypophosphite ion, which is responsible for P-H cleavage. On the other hand, on Cu (111), the s-orbital of H and the s-orbital of P in a hypophosphite ion interact simultaneously with the p-orbital of Cu (111). This interaction barely induces an anti-bonding interaction between H and P in the hypophosphite ion. Such a difference in orbital interaction structures should be related to P-H cleavage activity and the reactivity difference of hypophosphite ion on each metal surface. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623782] All rights reserved.

The elementary steps of the reactions of hypophosphite ions with Cu, Ni, and Pd were calculated theoretically using Density Functional Theory (DFT) to demonstrate the reaction mechanism and gain insight at the molecular level. The elementary steps of these reactions are adsorption, dehydrogenation, and oxidation (hydroxyl base attack). In the adsorption step, hypophosphite ions adsorb onto each surface spontaneously with stabilities in the order of Ni (111) &gt; Pd (111) &gt; Cu (111). In the dehydrogenation step, hypophosphite ions dehydrogenate on Ni (111) and Pd (111) with small reaction barriers, whereas they react on Cu (111) with a large reaction barrier. The large reaction barrier on Cu (111) is not compensated for by the adsorption energy on the surface. In the oxidation step, dehydrogenated anions on each metal surface react spontaneously with the hydroxyl base. The reaction barriers on each metal surface in this step are not so significant compared to the adsorption energies on each surface, suggesting that a reaction barrier of hypophosphite ion oxidation should exist in the dehydrogenation step and only be observed for Cu (111). This proposition elucidates the experimental catalytic behaviors of metal surfaces in the electroless deposition process using hypophosphite ions. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3609000] All rights reserved.

To elucidate the influence of surface defects, such as steps, on the oxidation of a reducing agent that is used in the electroless deposition process, we theoretically analyzed the reaction behavior of hypophosphite ion around the defect using density functional theory calculations. The reason why we chose the hypophosphite ion is that it is a typical reducing agent and reacts through a universal reaction mechanism. In this analysis, we focused on the dehydrogenation reaction, which is the rate-determining step in the oxidation pathway. Pd and Cu surfaces were chosen as the metal surfaces, because they exhibit completely different catalytic activity from each other, both experimentally and theoretically. Our calculations showed that the surface defect stabilized the final state of dehydrogenation on both Pd and Cu surfaces, which indicates that the defect accelerates the oxidation of the hypophosphite ion. In the final state of dehydrogenation, dissociated hydrogen adsorbs on the hollow site, which appears on the slope of the defect. More detailed analyses of the final state indicate that the stabilization effect by the surface defect originates from the highly efficient interactions between the dissociated hydrogen and the slope. The molecular orbital structure on this slope is distorted, which leads to high electron density around the slope that enables the highly efficient interactions between the hydrogen and the slope. © 2013 Elsevier Ltd.

The acceleration effect of thiourea on an electroless Ni deposition reaction was analyzed through experimental and theoretical approaches. In the experimental approach, the entire deposition process was physically separated into the anodic and the cathodic reactions by preparing two cells connected by a salt bridge. The cells contained either a bath without metal (Ni) ions or a bath without a reducing agent (hypophosphite ions). The current flowing between the two separated baths increased when thiourea was added only to the anodic reaction bath, which indicated that the acceleration effect of thiourea was mainly on the anodic reaction of the hypophosphite ions. Based on this experimental result, in the theoretical calculation approach, a co-adsorption system consisting of thiourea, hypophosphite, and a Ni metal surface was analyzed using density functional theory. Among all the elementary steps of a hypophosphite reaction, thiourea primarily should promote the adsorption step owing to the following two factors. One was the molecular interaction between thiourea and the hypophosphite ion. The other was the restructuring of the electronic states of the Ni surface owing to the adsorption of thiourea, which enhanced the interaction between hypophosphite and its adsorption site on the Ni surface. © 2012 Elsevier Ltd.

The acceleration effect of thiourea on an electroless Ni deposition reaction was analyzed through experimental and theoretical approaches. In the experimental approach, the entire deposition process was physically separated into the anodic and the cathodic reactions by preparing two cells connected by a salt bridge. The cells contained either a bath without metal (Ni) ions or a bath without a reducing agent (hypophosphite ions). The current flowing between the two separated baths increased when thiourea was added only to the anodic reaction bath, which indicated that the acceleration effect of thiourea was mainly on the anodic reaction of the hypophosphite ions. Based on this experimental result, in the theoretical calculation approach, a co-adsorption system consisting of thiourea, hypophosphite, and a Ni metal surface was analyzed using density functional theory. Among all the elementary steps of a hypophosphite reaction, thiourea primarily should promote the adsorption step owing to the following two factors. One was the molecular interaction between thiourea and the hypophosphite ion. The other was the restructuring of the electronic states of the Ni surface owing to the adsorp

Thiourea is well known and widely used additive for controlling the rate of electroless Ni deposition, and it is known to show complicated behavior in acidic/alkaline electroless deposition baths. To understand this, several experiments and theoretical calculations were performed. In the experiments, the adsorption of thiourea and the reducing agent (i.e., hypophosphite ions) on a Ni surface was characterized with a high-selectivity component at a right angle down to the sub-monolayer level using surface-enhanced Raman spectroscopy. By comparing the results with those obtained from the theoretical calculation, co-adsorption of thiourea and hypophosphite ions on the Ni surface was confirmed. Moreover, the acceleration or suppression effects of thiourea on the oxidation of hypophosphite ions on a Ni surface in acidic/alkaline bath were analyzed from the experimental and computational perspectives. Accordingly, an explanation that unifies both the acceleration and suppression mechanisms of thiourea in terms of its own fundamental characteristics is proposed; this will be one of the most important processes for industrial applications of electroless Ni deposition. (C) 2013 The Electrochemical Society. All rights reserved.

To elucidate the influence of surface defects, such as steps, on the oxidation of a reducing agent that is used in the electroless deposition process, we theoretically analyzed the reaction behavior of hypophosphite ion around the defect using density functional theory calculations. The reason why we chose the hypophosphite ion is that it is a typical reducing agent and reacts through a universal reaction mechanism. In this analysis, we focused on the dehydrogenation reaction, which is the rate-determining step in the oxidation pathway. Pd and Cu surfaces were chosen as the metal surfaces, because they exhibit completely different catalytic activity from each other, both experimentally and theoretically. Our calculations showed that the surface defect stabilized the final state of dehydrogenation on both Pd and Cu surfaces, which indicates that the defect accelerates the oxidation of the hypophosphite ion. In the final state of dehydrogenation, dissociated hydrogen adsorbs on the hollow site, which appears on the slope of the defect. More detailed analyses of the final state indicate that the stabilization effect by the surface defect originates from the highly efficient interactio

In order to elucidate the origin of magnetic properties and microstructure of electroless-deposited CoNiP films with perpendicular magnetic anisotropy, their initial growth processes were investigated mainly focusing upon the effects of bath factors. It was clarified that coercivity and grain size of the films changed widely with an increase in the ammonia concentration in the bath without varying the average film composition and crystal orientation. Detailed analysis of the growth processes clarified that an increase in ammonia concentration in the bath inhibited the growth of each crystallite, resulting in small grain size and coercivity, whereas it hardly affected the deposition activity of the catalytically-treated substrate surface and average film composition. (C) 1997 Published by Elsevier Science Ltd.

The growth process of etectroless nickel-phosphorous (NiP) films on nonconducting substrate was investigated quantitatively using tapping mode atomic force microscopy (TMAFM) with focus upon the nucleation density on the substrate surface. Three kinds of catalyzing processes were used for polyimide substrates to obtain nucleation densities of 900, 750, and 550 nuclei/μm2. The TMAFM observation showed that the film growth proceeds mainly through successive nucleation of fine "particles" with several nanometers in diameter and their three-dimensional growth, and that the nucleation density influences the state of aggregation of the particles and hence the resulting surface topography. The lower nucleation density developed the rougher surface with larger "grains" with a diameter of ca. 80 nm. However, the effect of nucleation density decayed with film growth and eventually vanished at a thickness of ca. 2000 nm due to successive nucleated. For comparison, the growth process of NiP on NiP coated Al substrate, which is used for rigid magnetic disk applications and has a higher nucleation density of 3000 nuclei/μm2, was also examined. This process resulted in a smooth surface without the formation of "aggregates." Based upon these results, the root-mean-square roughness and scaling analyses were performed to evaluate quantitatively the differences in growth process.

Effect of deposition site condition on the growth process of electroless CoNiP films was investigated by employing the intermediate 'treatment' step during the deposition. The effect of chemical species in the bath on the deposition sites, i.e., the film growth process, was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By changing the pH of the solutions for the 'treatment' step, it was found that the 'treatment' with higher pH solution resulted in the formation of smaller grains which possess lower perpendicular coercivity, Hc(perpendicular to). From these results, ammonia in the deposition bath results in the inhibition of the growth of crystallites, which leads lower Hc(perpendicular to). Based upon this, a model of the growth process of the CoNiP films was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.

The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection X-ray fluorescence (TXRF) and X-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16 nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide.