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We investigated a high electron mobility Ge FinFET fabricated by defect-free and roughness-free atomic layer neutral beam etching (NBE) compared with one fabricated by conventional plasma etching (PE). The etching interface roughness and defect were estimated by high-resolution transmission electron microscopy (TEM). In the case of using atomic layer defect-free NBE, the root-mean-square roughness of the Ge Fin sidewall surface is 1/3 times smaller than that using PE. Then, the electron mobility of Ge FinFET was improved by 1.65 times compared with that of a PE etched FinFET sample. For the subthreshold swing, the defect density of the interface between the Ge and gate dielectric film was improved by NBE. Ioff average currents of NBE and PE were around 18.1 and 57.6 nA/μm, respectively. As a result, NBE reduces the off-leakage current to 1/3 times less than PE. This corresponded to the differences in surface roughness and defect generation between NBE and PE. Therefore, we found that NBE could achieve a good performance by defect-free and atomically-flat etching the surface.

We have demonstrated a thermally managed Si nanopillar/SiGe composite structure. Our fabricated defect-free Si nanopillar channel structure showed a 1/100 times lower thermal conductivity than Si bulk thanks to the control of the phonon transports. The results of thermal conductivity measurements clarified that the nanopillar structure could eliminate electron-phonon scattering. As such, this structure represents a promising solution for advanced CMOS technologies.

Current nanodevices face many difficulties, one of which is the well-known issue of short-channel effects (SCEs). SCEs cause significant degradation in device characteristics. To overcome this issue, 2D materials have been studied since 2000. This article reveals the motivation for research on 2D materials for device application.

X-ray photoelectron spectroscopy (XPS) is used to analyze 4-META resin and enamel that are debonded at an adhesive interface. The XPS spectra showed two chemical states for Ca: one resulted from Ca of hydroxyapatite and the other, an unknown chemical state, suggested that Ca was chemically bonded with 4-META. We postulate that for a chemical reaction of 4-META and hydroxyapatite, the chemical structure of carboxyl groups will resemble that of calcium phthalate. Hence, calcium phthalate was used as a reference material. Additionally, the spectra obtained from the adhesive interface and the mixture of calcium phthalate with hydroxyapatite particles were compared using peak deconvolution analysis. XPS analysis revealed that the chemical bond of 4-META with enamel resembled the chemical state of Ca in calcium phthalate. Consequently, we suggest that Ca of the enamel and the carboxyl group of 4-META were chelate-bonded at the interface.

We have experimentally clarified the origin of low-frequency noise, which limits the coherence-time in Si quantum bit (qubit), utilizing cryo-CMOS. At cryogenic temperature (2.5 K), significantly enhanced $1/f$ noise is observed in Si MOSFETs, while it is not seen at room temperature. Interface trap density dependence of noise in Si MOSFETs, changing the surface orientation, revealed that the cryogenic $1/f$ noise is governed by carrier number fluctuation and we identified that the origin of the $1/f\mathrm{noise}$ is interface trap at cryogenic temperature, for the first time. The present study demonstrates that the experiments using well-investigated MOSFETs can provide new knowledge on Si qubits, which it is hardly possible to investigate using Si qubit as itself.

This study was aimed at investigating the protective effects of glass ionomer cement (GIC) and surface pre-reacted glass ionomer (S-PRG) fillers used as dental restorative materials on demineralization of bovine enamel. GlasIonomer FX ULTRA (FXU), Fuji IX GP Extra (FIXE), CAREDYNE RESTORE (CDR) were used as GICs. PRG Barrier Coat (BC) was used as the S-PRG filler. They were incubated in a lactic acid solution (pH = 4.0) for six days at a temperature of 37 &deg, C. The mineral was etched from the enamel surface, and a large number of Ca and P ions were detected in solution. The Al, F, Na, Sr, and Sr ions were released in GICs and S-RPG fillers. The Zn ion was released only in CDR and the B ion was released only in BC. The presence of apparent enamel prism peripheries was observed after six days of treatment for the group containing only enamel blocks. pH values for the FXU, FIXE, CDR, BC, and enamel block groups after six days were 6.5, 6.6, 6.7, 5.9, and 5.1, respectively. Therefore, the observed pH neutralization effect suppressed progression of caries due to the release of several ions from the restoratives.

This study developed a promising approach (low-temperature plasma polymerization with allylamine) to modify the titanium (Ti) surface, which helps the damaged tissue to heal faster. The Ti surface was first cleaned by argon (Ar) plasma, and then the functional amino-groups were coated on the Ti surface via plasma polymerization. The topography characteristics, wettability, and optimal plasma modification parameters were investigated through atomic force spectroscopy, secondary ion mass spectroscopy, and response surface methodology (RSM). Analytical results showed that the formation of a porous surface was found on the Ar plasma-modified Ti surfaces after Ar plasma modification with different parameters. The Ar plasma modification is an effective approach to remove surface contaminants and generate a porous topography on the Ti surface. As the Ti with Ar plasma modification was at 100 W and 190 m Torr for 12 min, the surface exhibited the maximum hydrophilic performance. In the allylamine plasma modifications, the contact angle values of the allylamine plasma-modified Ti surfaces varied between 70.15&deg, and 88.26&deg, in the designed parameters. The maximum concentration of amino-groups (31.58 nmole/cm2) can be obtained from the plasma-polymerized sample at 80 W and 150 mTorr for 22 min. Moreover, the cell response also demonstrated that the allylamine plasma-modified Ti sample with an optimal modification parameter (80 W, 22 min, and 150 mTorr) possessed great potential to increase cell adhesion ability. Thus, the optimal parameters of the low-temperature plasma polymerization with allylamine can be harvested using the RSM design. These data could provide new scientific information in the surface modification of Ti implant.

The aim of this study was to improve the cytocompatibility and differentiation of human bone marrow-derived mesenchymal stem cells on the surface of titanium implants by immobilizing biofunctional molecules on their surface. Gly-Arg-Gly-Asp-Ser (GRGDS) peptides, human plasma fibronectin (pFN), or type I collagen from calf skin (Col) was covalently immobilized on the titanium surfaces. Twice as many cells attached to the Col- and pFN-immobilized titanium surfaces than attached to the as-polished surface control. The ALP activity of the cells, as well as the mineralized nodule formation, was significantly higher on the Col- and pFN-immobilized titanium surfaces than on the as-polished surfaces. These results indicate that the immobilization of biofunctional molecules such as Col and pFN on titanium surfaces enhances the attachment, spreading, proliferation, and differentiation of human bone marrow-derived mesenchymal stem cells, which may lead to a more rapid bone-titanium integration.

We fabricated high aspect ratio 10-nm Si nanopillar (NP) array structures with a few-tenths-nm-gap arranged by fusing biotemplate and neutral beam etching processes to investigate the wettability [e.g., contact angle (CA)] with and without surface silicon oxide film. The NP array with silicon native oxides in all gaps exhibited super-hydrophilicity due to the chemical liquid-solid interface interaction and larger surface area than the Si flat surface thanks to the NP structure. These phenomena can be explained by using the Wenzel model. In contrast, when we selectively removed the native oxide on Si NP surface with our radical treatment, a gap variation from 11 to 43 nm stably resulted in a CA of more than 96° (hydrophobicity) with a maximum of 115°. This can be explained by using the Cassie–Baxter model with a filling factor. Our findings demonstrate that controlled surface wettability can be achieved by combining our controllable gap silicon NP array structures and the surface with or without silicon native oxides. The gap of a Si NP fills with water due to the capillarity on a silicon native oxide, but on a pure stable silicon one with a defect-free surface, does not completely fill. We found that Si NP structures with controllable gaps exhibit a surface wettability ranging from super-hydrophilicity to high-hydrophobicity.

Hydroxyapatite (HA) coatings on titanium implants enhance rapid bone formation around the implant due to their osteoconductive property. The present study aimed to achieve a thin and uniform HA film coating on titanium implants by solution plasma treatment (SPT). Commercially pure titanium and porous titanium disks were employed. A pulse plasma generator was used on the disks for 30 min. Morphologic and crystallographic features of the deposited films were examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). To evaluate the wettability of the disks, water droplet (20 &micro, L) surfaces were measured using a contact angle analyzer. The initial attachment of osteoblast-like cells (MC3T3E1) on the titanium substrates before and after solution plasma treatment was evaluated by counting the number of attached cells after incubation for 4 h. After immersion in the mineralizing solution for up to seven days, no crystals were observed on the polished-Ti surface. A more uniform and dense precipitation of round and grown crystals with diameters of approximately 1&ndash, 5 &micro, m was observed on Ti-SPT. XRD clearly showed that the precipitated crystals on titanium disks were HA. The contact angle of the polished-Ti increased with time (&theta, = 37&deg, &ndash, 51&deg, ). The surface of the Ti-SPT remained hydrophilic (&theta, ˂ 5&deg, ) after up to 30 days of aging. The number of attached cells on the Ti-SPT after aging for 30 days remained above 85% of that on the Ti-SPT without aging. SPT in a mineralizing solution can be used to acquire a homogenous precipitation of HA on porous-surfaced titanium implants.

The aim of this study was to evaluate the effects of three different chemotherapeutic agents, following air-abrasive debridement, on surface chemical properties and cytocompatibility. Disks contaminated with Streptococcus gordonii biofilm were treated with air-abrasion and immersion in either 0.9% NaCl (Air + NaCl), 0.05% alkaline electrolyzed water (AEW) (Air + AEW), or 3% H2 O2 (Air + H2 O2 ). Noncontaminated and untreated titanium disks served as a control (As-polished). The efficacy of biofilm removal, magnitude of initial cytocompatibility toward human bone marrow mesenchymal stem cells, and surface chemical properties were determined. In all treatment groups, biofilms containing microorganisms were observed to be completely removed. The data showed discrepancies for cell affinities among treatment groups, whereby: (1) the number of cells attached to the Air + AEW treated surfaces was approximately two times greater than that to the Air + NaCl treated surfaces; and (2) cell spreading was significantly enhanced on the Air + AEW treated surfaces compared with the Air + NaCl or Air + H2 O2 treated surfaces. X-ray photoelectron spectroscopy data showed that the mean relative concentrations of nitrogen to titanium on the As-polished, Air + NaCl, Air + AEW, and Air + H2 O2 surfaces were 0.0079, 0.0237, 0.0071, and 0.0210, respectively, which would provide a clear understanding that these discrepancies could be attributed to sufficient removals of organic-nitrogen deposits at the same magnitude as the As-polished following the Air + AEW treatment. This study clarifies that chemical surface treatment with AEW, as an adjunctive to air-abrasive debridement may be beneficial in restoring surface properties for tissue integration. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:183-191, 2020.

We have demonstrated position controlled CVD growth of metal dichacogenide (WS 2 and SnS 2 ) by using patterned Si substrates. It was found that step edges effectively induced crystal nucleation and lateral crystal growth of 2D materials proceeded from there. Gas source CVD system applicable to industrial production has also been developed and WS 2 and SnS 2 synthesis have been confirmed.

We evaluate the impact of tunnel junction quality on the performance of tunnel field-effect transistors (TFETs). The interface between epitaxially grown channel and source surface was used as tunnel junctions. Performing a sequential surface cleaning procedure prior to epitaxial channel growth for heavily arsenic- and boron-doped Si surfaces improved the interface quality both for p- and n-TFETs. Simultaneously, the subthreshold swing (SS) values of the TFETs improved step-by-step with interface quality.

We investigated the enamel demineralization-prevention ability and shear bond strength (SBS) properties of 4-methacryloxyethyl trimellitic anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB)-based resin containing various amounts (0-50%) of bioactive glass (BG). Disk-shaped specimens were immersed in distilled water and ions released were analysed by inductively coupled plasma atomic-emission spectroscopy. Samples were also immersed in lactic acid solution (pH 4.6) to estimate acid-neutralizing ability. Brackets were bonded to human premolars with BG-containing resins and the bonded teeth were alternately immersed in demineralizing (pH 4.55) and remineralizing (pH 6.8) solutions for 14 d. The enamel hardness was determined by nanoindentation testing at twenty equidistant distances from the external surface. The SBS for each sample was examined. The amounts of ions released [calcium (Ca), sodium (Na), silicon (Si), and boron (B)] and the acid-neutralizing ability increased with increasing BG content. After alternating immersion, the specimens bonded with the BG-containing resin with high BG content were harder than those in the other groups in some locations 1-18.5 μm from the enamel surface. Bioactive glass-containing (10-40%) resin had bond strength equivalent to the control specimen. Thus, the SBS obtained for BG-containing resin (6.5-9.2 MPa) was clinically acceptable, suggesting that this material has the ability to prevent enamel demineralization.

The aim of this study was to examine the effect of NaOCl pretreatment on the biomechanical fixation of implant at the early healing stage of a rat model. Polished titanium cylindrical implants and disks were prepared, and one-half of these samples were dual acidetched. Then, one-half of both surfaces were chemically-cleaned by pretreatment with 5% NaOCl solution for 24 h. Morphological analyses showed that there was no significant difference between before and after NaOCl treatment. The wettability measurement demonstrated that NaOCl treatment secondarily converted both titanium surfaces from hydrophobic to superhydrophilic, accompanied by the removal of hydrocarbons from the titanium surfaces. Biomechanical push-in test indicated that the bone-titanium integration strength of the NaOCl-treated implants were significantly greater than that of the untreated implants (p

We investigated the effects of CO2 laser irradiation combined with acidulated phosphate fluoride (APF) application on the demineralization of enamel. APF gel was applied to the buccal enamel of human premolars and CO2 laser was applied. After the specimens were immersed in demineralization solution for 72 h, they were subjected to depth-dependent micro-CT and nanoindentation analyses. Micro-X-ray diffraction and X-ray photoelectron spectroscopy were performed to analyze the surfaces. Some surface regions of the enamel in specimens that were laser-irradiated with low output and APF-treated showed significantly higher values of MD and hardness than specimens treated with APF alone. A higher fluoride concentration in the enamel surface was observed in specimens treated with CO2 laser irradiation plus APF gel application. In conclusion, CO2 laser irradiation with low output is preferable to improve acid resistance.

The insertion of an amorphous WSi n (n = 12) film composed of W-atom-encapsulated Sin cage clusters is demonstrated to reduce the SBH to 0.32 eV at W/n-Si and to 0.51 eV at W/Ge/p-Si junctions, while significantly extending the estimated TDDB lifetime to > 10 years at 100 °C under 5 MV/cm stress for Cu MOS capacitors. This film was formed with an excellent contact hole coverage by using WF6 and SiH4 gas sources in a hot-wall thermal reactor. These film properties enable the direct Cu contact at S/D in CMOS.

Now, double-Gate device technology is widely used for enhancement of device characteristics of the scaled MOSFETs. Moreover, independent-double-gate devices have been proposed to enable V th adjustment. It is revealed that SRAM performance have been increased by introducing the independent-double-gate FinFET.

The authors developed extremely selective etching for making an atomically flat, defect-free germanium fin (Ge Fin) structure. The etching uses a hydrogen bromide (HBr) neutral beam (NB), and they investigated the etching reaction differences between the HBr NB and a Cl2 NB. No sidewall etching by HBr NB occurred at 90 °C, although that by Cl2 NB occurred at more than 90 °C. This was due to the different boiling points of GeBr4 and GeCl4 as the reacted layer was formed by NB irradiation on the Ge surface. As a result, the Ge sidewall etching by Cl2 NB occurred above 90 °C, whereas that by HBr NB did not occur at 90 °C. Additionally, nonvolatile bromide protected layers, such as GeBr4 and SiBrxOy, were deposited on the Ge sidewall and the SiO2 top surface in case of using HBr, respectively. Then, the authors succeeded in fabricating the atomically flat, defect-free Ge Fin structure with the extremely selective HBr NB etching. This result shows that HBr NB can more precisely achieve sub-10-nm scale atomic layer Ge etching for 3D Fin-type MOSFETs.

In case of using pure chlorine chemistry, Ge etching reactivity is three times higher than Si etching reactivity because of the larger lattice spacing in Ge. As a result, during the chlorine plasma etching of a Ge Fin structure, there are serious problems such as a large side-etching and large surface roughness on the Ge sidewall. Conversely, the authors found that several-ten nanometer-width Ge Fin structures with defect-free, vertical, and smooth sidewalls were successively delineated by chlorine neutral beam etching. Based on these results, the problems caused by chlorine plasma etching are considered to be due to the enhancement of chemical reactivity caused by defect on the sidewall with the irradiation of ultraviolet/vacuum ultra violet (UV/VUV) photons. Namely, it is clarified that the neutral beam etching could achieve real atomic layer etching by controlling the defect without any UV/VUV photons on the sidewall surface for future nanoscale Ge Fin structures.In case of using pure chlorine chemistry, Ge etching reactivity is three times higher than Si etching reactivity because of the larger lattice spacing in Ge. As a result, during the chlorine plasma etching of a Ge Fin structure, there are serious problems such as a large side-etching and large surface roughness on the Ge sidewall. Conversely, the authors found that several-ten nanometer-width Ge Fin structures with defect-free, vertical, and smooth sidewalls were successively delineated by chlorine neutral beam etching. Based on these results, the problems caused by chlorine plasma etching are considered to be due to the enhancement of chemical reactivity caused by defect on the sidewall with the irradiation of ultraviolet/vacuum ultra violet (UV/VUV) photons. Namely, it is clarified that the neutral beam etching could achieve real atomic layer etching by controlling the defect without any UV/VUV photons on the sidewall surface for future nanoscale Ge Fin structures.

Several-ten nanometer-width Ge Fin structure with defect-free, vertical and smooth sidewall were successively delineated by a neutral beam etching method using pure Cl 2 gas chemistry for developing three dimensional channel FETs. The cross-sectional profile of the Ge Fins tended to have bottom tails without undercuts beneath etching masks in the best etching conditions. The bottom tails were eliminated by increasing Cl neutral beam energy and increasing substrate temperature. Very precise dimension control became possible by adjusting those two conditions. High resolution TEM observations revealed that the Ge Fin sidewalls, which were supposed to be FET channels, etched by the neutral beam seemed very smooth in a substantially atomic level while those ones etched in a plasma had relatively rough surfaces due to plasma damages.

A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully immobilized on the titanium surface and improved the compatibility of the surface with HPDLCs. The Col-immobilized titanium surface could be used for forming ligament-like tissues around titanium dental implants.

We compared the electrical characteristics, including mobility and on -state current Ion, of n+-poly-Si/PVD-TiN stacked-gate FinFETs with different fin heights Hfin. The mobility was enhanced in devices with taller fins due to increased tensile stress. However, as gate length Lg decreases, Ion for devices with tall fins becomes worse, probably due to a high parasitic resistance Rp. Furthermore, Vth variation increased with increasing Hfin due to rough etching of the fin sidewall. Process technologies for reducing Rp and etching technology that yields smooth precise profiles are essential to exploit the high performance of tall FinFETs.

In this letter, we propose a synthetic electric field (SE) effect to enhance the performance of tunnel field-effect transistors (TFETs). The novel SE-TFET architecture utilizes both horizontal and vertical electric fields induced by a gate electrode that is wrapped around an ultrathin epitaxial channel. The drain current of the SE-TFET is increased up to 100 times in comparison with those of conventional TFETs. The subthreshold slope of the SE-TFET also improved, and enhanced to 52 mV/decade by scaling the channel width and channel thickness.

Gate-induced drain leakage (GIDL) has become a crucial factor of determining current characteristics in ultra-small devices where the junction doping concentration is abruptly graded. It should be effectively suppressed for the low standby power operation (LSTP) of highly scaled metal–oxide–semiconductor field effect transistor (MOSFET) devices. In this work, the effects of doping profile on GIDL current are thoroughly investigated. In order to adjust the doping profile, we set up two variables: peak-to-gate edge distance and doping gradient. Underlap length can be also determined by the difference of these two variables. Based on analyses of the combinational effects of peak-to-gate distance and doping gradient, the methods of minimizing GIDL are searched for LSTP operation of silicon (SOI) FinFET on 32 nm technology node. The effective suppression of GIDL current can be achived by a number of combinations made by those two variables, rather than by a unique solution. 2-D and 3-D maps plotting the permissible pairs of variables will be given as the results by numerical simulations. Also, on the way to the aim, a quantitative method of extracting GIDL will be also introduced, which is more physically reasonable compared with existing one.

This study investigated the corrosion properties of ion implanted nickel-titanium wire (Neo Sentalloy Ionguard) in artificial saliva and fluoride mouth rinse solutions (Butler F Mouthrinse, Ora-Bliss). Non ion implanted nickel-titanium wire (Neo Sentalloy) was used as control. The anodic corrosion behavior was examined by potentiodynamic polarization measurement. The surfaces of the specimens were examined with SEM. The elemental depth profiles were characterized by XPS. Neo Sentalloy Ionguard in artificial saliva and Butler F Mouthrinse (500 ppm) had a lower current density than Neo Sentalloy. In addition, breakdown potential of Neo Sentalloy Ionguard in Ora-Bliss (900 ppm) was much higher than that of Neo Sentalloy although both wires had similar corrosion potential in Ora-Bliss (450 and 900 ppm). The XPS results for Neo Sentalloy Ionguard suggested that the layers consisted of TiO(2) and TiN were present on the surface and the layers may improve the corrosion properties.

Finely powdered enamel was used to develop a prosthetic resin composite that has good mechanical properties and no potential to abrade opposing tooth structure. Bovine teeth were ground into powder and then the enamel particles were separated from the powder by centrifugation in bromoform-ethanol solution. The resin matrix consisted of UDMA (60 mole %) and Tri-EDMA (40 mole %). Camphorquinone (0.5 mass %) was added to the monomer as a photo-initiator. Fillers were incorporated directly into the resin matrix in amounts of 80 or 85 mass %. The flexural strength and Vickers hardness (Hv) were measured. The average flexural strength and Hv values for specimens having 85 mass % filler that had been subjected to heat treatment at 100 degrees C after light-curing were 95.2 and 109.8 MPa, respectively, which are higher than those for most commercial prosthetic resin composites. These findings suggest that a novel prosthetic resin composite with good mechanical properties can be made by loading finely powdered enamel into the resin matrix.

A sputtered titanium nitride (TiN) metal gate has systematically been investigated, and the dependences of TiN work function (TiN) and device performance on nitrogen gas flow ratio [RN=N2/(N2+Ar)] in sputtering and rapid thermal annealing (RTA) temperature (TR) are clarified. It is experimentally found that TiN slightly decreases from 4.87 to 4.78 eV with increasing RN from 17 to 83%, and it markedly decreases with increasing TR. The analysis of the electrical characteristics of fabricated metal–oxide–semiconductor field-effect transistors (MOSFETs) shows that the optimal RN range is 17–50%, and a higher RN offers a lower Vth owing to the lower TiN. The origin of TiN decrease with increasing RN and TR is discussed. The obtained results indicate that TiN can be controlled by sputtering and RTA conditions, and are very useful for setting the appropriate Vth for lightly doped channel devices such as a FinFET.

This paper presents the fin-height controlled TiN-gate FinFET CMOS technology based on the experimental carrier mobility data. The good current matching by tuning the N-channel fin-height and the excellent transfer performance in the fabricated TiN-gate CMOS inverter are demonstrated. The developed technologies are attractive to materialize the high-performance FinFET CMOS circuits.

We have developed a novel wafer-scale uniform layer-by-layer etching technology based on the etching reaction of oxygen molecules with Ge surfaces. The advantages of this etching technology are as follows. (1) Layer-by-layer etching can be achieved, yielding an atomically flat step-terrace surface. (2) Because of the very small activation energy (

The titanium nitride (TiN) gate electrode with a tunable work function has successfully been deposited on the sidewalls of upstanding Si-fin channels of FinFETs by using a conventional reactive sputtering. It was found that the work function of the TiN (phiTiN) slightly decreases with increasing nitrogen (N2) gas flow ratio, RN=N2/(Ar+N2) in the sputtering, from 17% to 100%. The experimental threshold voltage (Vth) dependence on the RN shows that the more RN offers the lower Vth for the TiN gate n-channel FinFETs. The composition analysis of the TiN films with different RN showed that the more amount of nitrogen is introduced into the TiN films with increasing RN, which suggests that the lowering of phi TiN with increasing RN should be related to the increase in nitrogen concentration in the TiN film. The desirable Vth shift from -0.22 to 0.22 V was experimentally confirmed by fabricating n+ poly-Si and TiN gate n-channel multi-FinFETs without a channel doping. The developed simple technique for the conformal TiN deposition on the sidewalls of Si-fin channels is very attractive to the TiN gate FinFET fabrication

We report successful growth of high-quality thin films with clean and completely precipitate-free surface, suitable for device applications, by applying a new concept and method to the substrates. The concept consists in generation of artificial steps of controlled height and width, and desired shape on the surface of the substrate. The width of the step is chosen so that it is equal to the double of the migration (surface diffusion) length of the atomic species in the growth process of the film. If precipitates occur, they will be selectively gathered to the step edge where the free energy is lowest. Using this new method, we have successfully obtained by MOCVD high-quality precipitate-free Bi-2223 and Bi-2223/Bi-2212-superlattice thin films on (100) SrTiO3 substrates with artificial steps of controlled width and height. These as-grown films have been further used to fabricate patterned intrinsic Josephson junctions. Completely precipitate-free films offer a strong advantage for integration, and generate new possibilities for the device fabrication.

This paper presents, for the first time, the experimental electron mobility in FinFETs with a (111) channel surface fabricated by the orientation-dependent wet etching. The maximum electron mobility (ueff) is around 300-cm2 /V-s, which is close to that in the (111) bulk MOSFETs. Moreover, the value of ueff is comparable or better than the reported ones in the usual FinFETs with a (110) channel surface prepared with careful surface treatments. This result indicates that the quality and channel surface roughness of the Si-fins by the orientation-dependent wet etching are much better than those fabricated by the conventional reactive ion etching (RIE) process.

YBCO films deposited from a stoichiometric (Y123) target via a large-area PLD system have consistently been found to be Y-rich in composition as well as characterized by pores. Use of an off-stoichiometric target with increased Ba and Cu content proved to be an effective method to compensate for the deficiency in barium and copper in the films. Films with composition closer to the ideal stoichiometric ratio have been obtained from the off-stoichiometric target, including significantly reduced pore density, improved microstructure and higher critical current density ( J c ) in excess of 2 MA/cm 2 at 77.3 K over a 2 ″ -diameter area. Furthermore, it was found out that the dense and smooth YBCO film deposited from the off-stoichiometric target needed ex situ oxygen annealing to reach fully-oxygenated state.

胃癌術後例の血中ビタミンB1値について検討した.対象は胃癌術後3カ月以上経過した112例で,ビタミンB1値を測定し大腸癌術後症例25例のB1値と比較した.また胃癌術後例で低値を示した症例にビタミンB製剤の内服投与を行いB1値の変動を検討した.さらに胃癌術後例にアンケートを行いビタミンB1低値例の背景因子を検討した.結果,胃切除後例の血中ビタミンB1値は平均2.9μg/dl,大腸癌術後例は3.0μg/dlで両群に有意差はなかった.またビタミンB1欠乏は胃癌術後例の12例(10.7%),大腸癌術後例の1例(4%)にみられ,両群に有意差はなかった.またビタミンB製剤の内服で全例B1値が上昇した.アンケートの結果では低値例では正常例と比し体重減少率が高かった.以上からB1値の低下は胃切除術に起因したものではないが,低値を示す例があり,適切な食事指導や投薬などの細かな配慮が重要であると考えられた.

The anodic corrosion behavior of an experimental Ag-15Pd-18Cu-12Au alloy in 0.1% Na(2)S solution in relation to its microstructure was investigated using potentiodynamic and potentiostatic polarization techniques with analyses of corrosion products by X-ray diffractometry, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The role of Pd in improvement of the corrosion resistance was also investigated. In the potential/current density curve, three distinct current peaks, at -520 mV (peak I), -425 mV (peak II) and -175 mV (peak III), were observed. The Ag-rich alpha(2) matrix with coarse Cu and Pd-rich lamellae was the most corrosion-susceptible region, and this region was preferentially corroded at peak I with the formation of granular deposits of Ag(2)S. A small amount of Ag-Cu mixed sulfide deposited on the Cu and Pd-rich coarse particles and dissolution of Ag as AgO(-) might have occurred in parallel with Ag(2)S formation at peak II. Enrichment of Pd on the alloy surface occurred at peak III due to preferential dissolution of Ag and Cu. A high level of corrosion resistance was attained with the formation of a thin Pd-rich sulfide film, which enhanced the passivity of the alloy in an alkaline sulfide solution. It was found that passivity is an important phenomenon not only for base metal alloys but also for noble metal alloys to maintain high levels of resistance to corrosion and tarnishing in sulfide environments.

The effectiveness of amorphous metal gate (MG) in suppressing low-frequency noise (LFN) for FinFETs has been thoroughly investigated. It was demonstrated that the amorphous TaSiN MGs with various atomic compositions provide flexible tuning of threshold voltage (V t ) as well as small V t variability, namely AVt. It was found that the TaSiN-MG FinFETs exhibit drastic reduction of LFN in comparison to the poly-crystalline TiN MG case. Modelling by 3D-TCAD reveals that work function variation (WFV) of the MG has a significant impact on LFN generation. Suppression of A Vt and LFN is highly beneficial to conduct further scaling of analog/digital components in SoC.

Three commercially available porcelains bonded to titanium were evaluated to determine the weakest zone of the titanium-porcelain bonding structures. Tensile bond tests were performed for these specimens (NO, DU, and VI) and for Ni-Cr alloy-porcelain bonding samples that served as controls. The maximum bond strengths between porcelain and titanium and the Ni-Cr alloy subjected to different metal surface treatments were compared. Sand blasting effectively increased bond strengths in titanium-porcelain bonding materials. No statistically significant differences in the maximum bond strengths were found between the NO sample and a control; however, sample NO exhibited greater maximum bond strength than DU and VI samples. The bond strengths increased with increasing area fractions of porcelain failure on fracture surfaces. The weakest zones were investigated based on the oxygen chemical states determined by electron spectroscopy for chemical analysis, which include bridging oxygen (Si-O-Si), nonbridging oxygen (Si-O(-) M(+)), and titanium oxide (O(2-)) states. We concluded that the titanium oxide layer is the weakest zone of titanium-porcelain bonding structures.

Fluctuation in drain induced barrier lowering (DIBL) has been investigated in detail for FinFETs with regard to work function variation (WFV) in the metal gates (MGs). The FinFETs with a polycrystalline TiN MG exhibit significantly larger fluctuation in DIBL than that for an amorphous TaSiN MG because of the WFV. The granular WFV of TiN was modeled using 3D TCAD simulation. By reproducing the DIBL fluctuation caused by the WFV, mechanism of how the WFV causes the DIBL fluctuation is discussed.

The corrosion behaviors of a commercial Ni-Ti alloy orthodontic wire and a polished plate with same composition in 0.9% NaCl and 1% lactic acid solutions were examined using an electrochemical technique, an analysis of released ions, and a surface analysis by X-ray photoelectron spectroscopy (XPS). The effect of polishing the wire on the corrosion was also examined. The XPS analysis demonstrated the presence of a thick oxide film mainly composed of TiO2 with trace amounts of Ni hydroxide, which had formed on the wire surface during the heat treatment and subsequent pickling processes. This oxide layer contributed to the higher resistance of the as-received wire to both general and localized corrosion in 0.9% NaCl solution, compared with that of the polished plate and the polished wire. The thick oxide layer, however, was not stable and did not protect the orthodontic wire from corrosion in 0.1% lactic acid solution.

Three precious metal alloys, Type IV gold alloy, 14 K gold alloy, and silver-based alloy, were treated with different surface modifications including a metal primer (VBATDT) application, a SiOx coating method, high-temperature oxidation, modification method with a liquid Ga-Sn alloy, and tin electroplating. Then thin PMMA films were bonded with a resin containing 4-META. Water durability at the adhesion interface was evaluated after water immersion, followed by thermal cycling used liquid nitrogen. The weakest zone at the interface was investigated using XPS only for the Ag-Pd alloy specimens that had been surface-treated with as-polishing, adhesive primer, and the SiOx coating method, since peeling of the PMMA film on the surface of specimens surface-treated by other methods was not observed. Metal elements were detected from the resin side at the adhesion interface. The chemical states of Cu in the resin before argon ion etching were characterized as metal oxides and/or states of chemical interaction with 4-META, VBATDT, or SiOx.

Variability of TiN FinFET performance is comprehensively studied. It is found that the variation of the in the FinFET occurs and the standard deviations of the of nMOS and pMOS FinFETs are almost the same. From the analytical results, it is found that the variation of the TiN FinFET is due to the work function variation (WFV) of TiN metal gate. The WFV is also responsible for the on-current variation.

A compact model (CM) for fin-type FETs (FinFETs) was successfully developed and applied to variability analysis of a fabricated state-of-the-art metal-gate (MG) FinFET. By combining the statistical measurements with the CM calibration, V th variation was, for the first time, broken down into structure-based (silicon fin thickness and gate length) and material-based (gate work function) components. As a result, the measured variation of MG FinFET performance was successfully reproduced by the CM. Characterization using the CM with the measured statistical data provides insight on the gate work function variation of 16 meV in short-channel molybdenum (Mo) gate FinFETs.

Cointegration of titanium nitride (TiN)-gate high-performance tied-gate three-terminal FinFETs with symmetric gate-oxide thicknesses (tox1=tox2=1.7 nm) and variable threshold-voltage Vth independent-gate four-terminal (4T) FinFETs with asymmetric gate-oxide thicknesses (tox1=1.7 nm for the driving-gate-oxide, and tox2=3.4 or 7.0 nm for the control-gate-oxide) has been successfully developed using conventional reactive sputtering, two-step Si-fin and gate-oxide formation, and resist etch-back processes. A significantly improved subthreshold slope and an extremely low OFF-state current Ioff are experimentally confirmed in the asymmetric gate-oxide thickness 4T FinFETs by increasing the control-gate-oxide thickness to twice or more the driving-gate-oxide thickness. The developed techniques are attractive for high-performance and low-power FinFET very large-scale integration circuits

A case of lichen planus of the buccal mucosa in a 52-year-old female is reported. Her teeth were cemented by a fixed bridge in a dental clinic three years earlier. A few days later, she had a constant pain in her oral mucosa that was worsening. She visited our hospital with this swelling, so the lesion was examined. Lichen planus was recognized in the biopsy specimen of the lesion. She had a medical history of metal allergy. Patch test for dental metal sensitivity was used to investigate the problem. Positive reactions were observed for tin, copper, chromium, gold, and palladium. Investigation was done by metal biopsy of the surface of the resin disk inscribed on her prostheses. The minute amounts of biopsy on the resin disk were analyzed by ESCA. It was found that her prostheses were made of Au-Ag-Pd and Ag-In-Sn alloys. These results suggested that this case may have lichen planus caused by allergy to dental alloys. Therefore, her metal prostheses were removed and a temporary restoration of resin for 10 months was done. Finally, a titanium prostheses was applied. Her condition has remained good without any allergic reaction. It seemedthat this treatment was successful because her lesion recovered.

Adhesion of 4-META to Au-In alloy was improved by adding In equivalent to .15% of Au content. On the basis of the results of Au-In alloys analyzed by XPS, the present study investigated the reason why adhesion of the Au-In alloy was improved. The O 1s spectrum could be separated into three oxygen chemical states, In2O3, chemisorbed H2O, and physisorbed H2O. The amount of chemisorbed H2O decreased remarkably with increasing amount of In. It is considered that the poor adhesive ability of the pure gold and alloys containing only small amounts of In was due to the chemisorbed H2O molecules and insufficient indium oxide on the alloy surface. It was established that excellent adhesion requires an oxide with chemical affinity for 4-META to cover at least 50% of the alloy surface.

To eliminate precipitates–segregates that can easily occur on the thin film surfaces of the multicomponent materials for electronics, a new approach is proposed, consisting of the following aspects: first , on the substrates, artificial steps of predefined height and width are produced, and second , films are grown on such substrates. The width of the step is taken equal to the ‘double of the migration length’ of the atomic species depositing on the substrate. In these conditions, precipitates migrate and gather at the step edges where the free energy is lowest and the resulting totally precipitate-free surface of the film on the step is suitable for device applications or integration purposes. The method has several other important advantages and they are discussed in the text. Using this new approach we present successful fabrication of a mesa structure showing intrinsic Josephson effect. We have used thin films of Bi-2212/Bi-2223 superstructure grown by MOCVD on (001) SrTiO 3 single crystal substrates with artificial steps of about 20 μm width.

Cu oxide has been deoxidized in an extremely low oxygen partial pressure atmosphere. The oxygen was evacuated to 10-28 atm using a newly developed oxygen reduction system (ORS). It was experimentally demonstrated that the surface oxide of Cu film was completely removed by exposure to such an environment at 200 °C. The proposed deoxidization reaction can be used as a new Cu surface cleaning technique.