bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Substrate Effect in Chemically Amplified Resist on Silicate-Glass
Authors: Mori Shigeyasu , Takashi Fukushima Takashi Fukushima , Yuichi Sato Yuichi Sato
Published: October 2002

The substrate effect of chemically amplified (CA) resists on boron-phosphorous-silicate-glass (BPSG), boron-silicate-glass (BSG), phosphorous-silicate-glass (PSG) and non-doped-silicate-glass (NSG) has been investigated using a surface analysis technique. The resist pattern of a negative-tone CA resist on BPSG, PSG and BSG substrates has an undercut profile, and that of a positive-tone CA resist on these substrates has a footing profile. To clarify the interaction between CA resists and BPSG, BSG, PSG and NSG substrates, the surface of these substrates was analyzed by electron spectroscopy for chemical analysis (ESCA). It was found that there are boron oxides and/or phosphorous oxides on the surface. These oxides are considered to contribute to the undercut profile of the negative resist and footing profile of the positive resist, and to quench photo-generated acids in the resists. Further, cleaning of the surface of a BPSG substrate with H2SO4/H2O2 is results in improvement of the pattern profile.
Relationship between Remaining Solvent and Acid Diffusion in Chemically Amplified Deep Ultraviolet Resists
Authors: Itani Toshiro , Yoshino Hiroshi , Hashimoto Shuichi , Yamana Mitsuharu , Norihiko Samoto Norihiko Samoto , Kunihiko Kasama Kunihiko Kasama
Published: October 2002

For clarification of the diffusion path of photogenerated acid in the resist film, the prebake temperature dependence and tert-butoxycarbonyl ( t-BOC) blocking level dependence on acid diffusion were investigated for chemically amplified deep ultraviolet (DUV) positive resists. The resists consisted of a t-BOC protected polystyrene base resin and a 2,4-dimethylbenzenesulfonic acid derivative as a photoacid generator (PAG). The concentration of remaining solvent in the resist film decreased as the prebake temperature or t-BOC blocking level increased. The acid diffusion coefficient was almost independent of exposure dose; however, it decreased with increasing prebake temperature or blocking level. Therefore, it was considered that the concentration of remaining solvent in the resist film corresponds to one of the acid diffusion paths. Moreover, hydrophilic OH sites, whose concentration was the reciprocal of the blocking level, were also considered to correspond to a diffusion path in the polymer matrix, based on the fact that the acid diffusion length increased gradually with decreasing t-BOC blocking level, even when the solvent concentration remained constant. Based on the experimental analysis results, the existence of two diffusion paths, as well as of explicit relationships among the remaining solvent, t-BOC blocking level and acid diffusion length was confirmed.
Optimization of a High-Performance Chemically Amplified Positive Resist for Electron-Beam Lithography
Authors: Tetsuro Nakasugi Tetsuro Nakasugi , Hitoshi Tamura Hitoshi Tamura , Hiromi Niiyama Hiromi Niiyama , Satoshi Saito Satoshi Saito , Naoko Kihara Naoko Kihara , Takuya Naito Takuya Naito , Makoto Nakase Makoto Nakase
Published: October 2002

We report on sub-0.1 µm electron-beam (EB) lithography using a new chemically amplified positive resist with a stabilizing additive. Diphenylamine (DPA) was incorporated into the resist formulation as a stabilizing additive. DPA improves the post-exposure delay (PED) stability. Even after a PED of 60 min in a clean-room atmosphere (NH3 concentration ∼20 ppb), no insoluble surface layer was observed for the resist with DPA. High sensitivity and resolution could be achieved by optimizing process conditions such as baking and developer. 0.1 µm lines-and-spaces (L/S) patterns and 0.08 µm hole patterns were obtained using a 50 kV variably shaped beam EB system. The practical sensitivity was 6 µC/cm2 for L/S patterns. Our resist system also shows good performance as an etching mask. A 0.1 µm diameter hole which was 0.5 µm etched in silicon oxide using a 0.5 µm thick resist could be obtained in this experiment.
Focused Ion Beam Lithography Using Ladder Silicone Spin-on Glass as a Positive Resist
Authors: Suzuki Kohei , Yamashita Motoji , Nobuyuki Kawakami Nobuyuki Kawakami , Akimitsu Nakaue Akimitsu Nakaue
Published: October 2002

Focused ion beam lithography using ladder silicone spin-on glass as a positive resist has been demonstrated. This lithographic technique utilizes the structural change of ladder silicone spin-on glass (LS-SOG) to a silicon-dioxide-like structure. A 60-nm-width space pattern and a 90-nm-diameter hole pattern have been fabricated using ion doses of 6.2×1013/ cm2 and 1.2×1014/ cm2, respectively. The development mechanism and the sensitizing effect of post-exposure baking have been investigated using fourier transform infrared spectroscopy (FTIR).
Cl Atom Desorption by Chemical Reaction with Al Atom on Si(111) 7 × 7 Studied by Scanning Tunneling Microscopy
Authors: Masakazu Baba Masakazu Baba , Shinji Matsui Shinji Matsui
Published: October 2002

The chemical reactivity of Al-Cl and Cl-Si atoms has been studied by in-situ scanning tunneling microscopy (STM). Cl atoms are first adsorbed at room temperature on a Si(111)7×7 surface in an ultra-high vacuum STM. Next, Al atoms are evaporated on this surface. As a result, the Al atoms desorb the Cl atoms from the Si surface, because Cl atoms react more strongly with Al atoms than with Si adatoms.
Low-Temperature Growth of SiO2 Films by Electron-Induced Ultrahigh Vacuum Chemical Vapor Deposition
Authors: Nakano Koji , Tetsuhiro Horie Tetsuhiro Horie , Hitoshi Sakamoto Hitoshi Sakamoto
Published: October 2002

Room temperature growth of SiO2 films was carried out using the method of electron-induced ultrahigh vacuum chemical vapor deposition with disilane ( Si2H6) and oxygen ( O2). The films were grown selectively on a Si(100) surface irradiated by an electron beam with an energy of 0.6–17 keV and a current density of 0.03–2.7 mA/cm2. The [O2]/[Si2H6] gas mixing ratio of 2 was most effective for obtaining the highest growth rate of the films. From the results of film characterization by refractive index, stoichiometry and catastrophic breakdown electric field measurements, we found that the films are much the same as thermally oxidized SiO2 films. Dependence of the growth rate on the incident angle of the electron beam on a surface and on the primary electron energy suggested that the growth kinetics of the SiO2 films are managed by an amount of secondary electrons generated from the film surface.
Electron Beam Assisted Chemical Etching of Single Crystal Diamond Substrates
Authors: Jun Taniguchi Jun Taniguchi , Iwao Miyamoto Iwao Miyamoto , Naoto Ohno Naoto Ohno , Satoshi Honda Satoshi Honda
Published: October 2002

Electron beam assisted chemical etching (EBACE) with oxygen gas is applicable to direct fine patterning of single crystal diamond substrates. A scanning electron microscope (SEM) combined with an oxygen gas introduction system was used for EBACE of diamond. In order to prevent surface charge-up during etching and SEM observation, a hydrocarbon contamination layer, which has conductivity and can be deposited during electron beam irradiation using oil vapor in a vacuum system, was used. Etching characteristics of single crystal diamond substrates by EBACE with oxgen gas were mainly investigated. It was found by in-situ SEM observation that hole, line and rectangular patterns with several µm2 area and sub-µm depth into the diamond substrates were successfully fabricated by EBACE utilizing spot, line and raster scanning modes of the SEM. The depths of holes and rectangular patterns were proportional to electron beam exposure times. Etched areas of line and rectangular patterns were larger than scanned area. An etching yield of 1.99 ×10-2 carbon atoms of diamond per electron has been observed for EBACE using oxygen gas.
Characterization of Directly Deposited Silicon Films Using Low-Energy Focused Ion Beam
Authors: Junichi Yanagisawa Junichi Yanagisawa , Noriyuki Onishi Noriyuki Onishi , Hiromasa Nakayama Hiromasa Nakayama , Kenji Gamo Kenji Gamo
Published: October 2002

Direct deposition of silicon and silicon-oxide films using a 100 eV Si2+ focused ion beam (FIB) was performed and the dependence of the film composition on the irradiation interval (time between consecutive exposures of the pixel) and the oxygen pressure was investigated. From the Auger electron spectroscopy (AES) measurement, it was found that the amount of oxygen incorporated in the deposited film increased with increasing irradiation interval and oxygen pressure, and that the oxygen was chemically bonded with silicon. For a deposition performed in an oxygen atmosphere at a pressure of 8 ×10-6 Torr, oxygen inclusion was about 80% of thermally oxidized SiO2. Resistivity of the deposited silicon-oxide film was about 2 MΩ·cm. The present result suggests that both pure Si and silicon-oxide films can be formed using the same low-energy Si2+ FIB direct deposition only by changing the deposition atmosphere.
Evaluation of the Mott Polarimeter in the Electron Spin Polarization Scanning Electron Microscopy
Authors: Masatoshi Kotera Masatoshi Kotera , Keiji Tamura Keiji Tamura
Published: October 2002

In order to determine the optimum conditions for the Mott polarimeter which give the highest signal contrast and maximize the electron detection efficiency, electron scattering phenomena in the target are quantitatively discussed. The Mott scattering cross section for spin polarized electrons is used in this analysis. The angular deflection and the spin polarization transfer of electrons for a single scattering event are calculated sequentially using the Monte Carlo method, and three-dimensional trajectories of electrons are simulated. Based on the agreement with the experimental results of the asymmetry variation with the target thickness, the calculation is extended to determine the optimum target thickness under a definition of the figure of merit of the Mott polarimeter.
Dielectric Properties of ( 1-x)CaTiO3–xLa(Zn1/2Ti1/2)O3 Ceramics at Microwave Frequencies
Authors: Yeo Dong Hun , Kim Jae Beom , Moon Jong Ha , Seok Jin Yoon Seok Jin Yoon , Hyun Jai Kim Hyun Jai Kim
Published: October 2002

The microwave dielectric properties and sintering conditions of the (1- x)CaTiO3– xLa(Zn1/2Ti1/2)O3 system were investigated for the development of a microwave dielectric material having a high Q·f
0, moderate ε

r
and zero τ
f
. A microwave dielectric material having ε

r
of 50, Q·f
0 of 38000, and τ
f
of zero was obtained from the compound 0.5CaTiO3–0.5La(Zn1/2Ti1/2)O3. The sintering temperature of compounds decreased with increasing amount of La(Zn1/2Ti1/2)O3 and a cooling rate of less than 3° C/min was optimum for obtaining the best Q·f
0 for all compositions tested.
Spontaneous Layer Twist in a Stripe Texture of Chiral Ferroelectric Smectics Observed by Synchrotron X-Ray Microdiffraction
Authors: Takanishi Yoichi , Iida Atsuo , Ishikawa Ken , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: October 2002

We noticed stripe domains accompanied with a zigzag defect loop, which cannot be explained as simple zigzag walls. The structure was analyzed using a synchrotron X-ray microbeam with a space resolution of 5×5 µ m2. We propose that the structure is a chevron structure with a spontaneous layer twist, which is predicted to exist by the continuum theory but has not yet been observed experimentally.
Molecular Dynamics Simulation of Electrostatic Structural Phase Transition in Ferroelectric Poly(vinylidene fluoride)
Authors: Nobuyuki Takahashi Nobuyuki Takahashi
Published: October 2002

Molecular dynamics simulations have been performed for a model crystal of ferroelectric poly(vinylidene fluoride) to examine the effects of the long-range part of the electrostatic interaction on the crystal structure and the polarization. The initial polar structure of the form-I crystal is transformed spontaneously to a nonpolar crystal structure in the absence of the long-range part of the electrostatic interaction. The significant role of the electrostatic interaction on the order of dipoles is demonstrated for this ferroelectric polymer.
Structure Analysis of ZnO–TeO2 Glasses by Means of Neutron Diffraction and Molecular Dynamics
Authors: Matsumoto Hiroshige , Mabuchi Toshiro , Yuzo Shigesato Yuzo Shigesato , Itaru Yasui Itaru Yasui
Published: October 2002

Structures of x ZnO–(1-x) TeO2 glasses (x=0.1, 0.2, 0.3) were investigated by means of neutron diffraction and molecular dynamics. Modified Keating three-body potential and imaginary negative point charge were applied to the simulation, which successfully represented complex structure units in tellurite glasses. It was concluded that TeO3+1 was a dominant component in the network structure of the zinc tellurite glasses. The fraction of the TeO3+1 unit was almost independent of the amount of ZnO. Zinc atoms are considered to play a role in network formation in the glasses, which was estimated on the basis of the coordination state of tellurium.
Dependence of Temperature of Collision-Cooled Ions Stored in an RF Trap on Trapping Parameters
Authors: Yoshiki Moriwaki Yoshiki Moriwaki , Maki Tachikawa Maki Tachikawa , Tadao Shimizu Tadao Shimizu
Published: October 2002

The kinetic property of ions stored in an RF-quadrupole trap is investigated theoretically and experimentally. We observed the dependence of the temperature of the ions on the trapping parameter (q
z) and the number of ions in the presence of He buffer gas. The results are well explained by a model which represents the collisional energy transfer between ions and neutral molecules assuming a kinematic collision between them.
Polarizing Fabric Screen for Liquid Crystal Display System
Authors: Masao Uetsuki Masao Uetsuki
Published: October 2002

Using a polarizing fiber of poly(vinyl alcohol) and a nonpolarizing fiber of 6-nylon as a weft and a warp, respectively, a polarizing fabric was woven in a satin fashion. After calendering the fabric and coating with a transparent resin, aluminum vapor was deposited on the rear surface to produce a reflective layer. The outer surface of the aluminum layer was pasted with a poly(vinyl chloride) sheet to complete the polarizing fabric screen, which filtered nonpolarized illuminant light to facilitate visualization of dim images from a liquid crystal projector. When the polarizing fiber array was oriented vertically, the light forming the image was diffused trapezoidally in a horizontal plane to increase the viewing angle and the light recurrence of the projected image giving a clear picture with no hotspot even in a relatively bright room.
Stress of Corrugated Fiberboard Made by Compression under Uniform Bending of Moment Axis in Machine Direction (On Single Wall Fiberboard with Symmetrical Thickness Strength)
Authors: Matsushima Satoru , Matsushima Shigeo , Yano Tadasi
Published: October 2002

We investigated stress generation in a semichemical corrugated medium (SM) by compressional forces under uniform bending with the bending moment axis of the machine direction (MD) in single-wall corrugated fiberboard (SWCF), and attempted to derive an elastic expression for its generation stress σ sp. Using this expression, the analysis of σ sp was carried out. Values of the lateral force W
sx and fixed moment M
s0 per unit length at the joint between kraftliner (KL) and SM are determined, and relationships between those values and the shape of SWCF are considered. The following results are obtained from the expression. The maximum value σ pmax
of σ sp is found at the joint on the outer surface of SM. W
sx, M
s0 and σ pmax
increase markedly with the increase of wavelength L and decrease markedly with the increase of wave height h for SM.
Electrical Characteristics of Polycrystalline Silicon Thin Film Transistors to Improve an ON/OFF Current Ratio
Authors: Min Byung-Hyuk , Cheol-Min Park Cheol-Min Park , Min-Koo Han Min-Koo Han
Published: October 2002

We have proposed and fabricated novel polycrystalline silicon thin film transistors (poly-Si TFTs) to have the properties of an offset gated structure in OFF state, while acting as a non-offset structure in ON state. The fabrication process is compatible with the conventional non-offset poly-Si TFT process and does not require any additional photolithographic step. Our experimental results show that the leakage current of the new device is two orders of magnitude lower than that of the non-offset device, while the ON current of the new device is almost identical with that of the non-offset device. Compared with the conventional device, it is found that the leakage current increase slowly with the negative gate voltage decrease and the ON/OFF current ratio is improved remarkably.
Octahedral-Structured Gigantic Precipitates as the Origin of Gate-Oxide Defects in Metal-Oxide-Semiconductor Large-Scale-Integrated Circuits
Authors: Itsumi Manabu , Akiya Hideo , Ueki Takemi , Tomita Masato , Yamawaki Masataka
Published: October 2002

Analysis by TEM-energy-dispersive-X-ray-spectroscopy indicates that the majority of the octahedral structure found just under the oxide defect with Czochralski Si is void. This is contrary to previously reported results suggesting that the octahedral structures found in Si bulk are filled with amorphous SiO2. We investigate three models to explain our results. The first model, which we think most probable, suggests that the void formation occurs during Si crystal growth. The second model indicates that octahedral structures full of SiO2 are formed during Si crystal growth and, after wafer slicing, much of the SiO2 is removed. The third model suggests that the void is formed during copper decoration. We show some experimental results that are inconsistent with the second and third models.
Analysis of Mechanisms for Hot-Carrier-Induced VLSI Circuit Degradation
Authors: Huh Yoonjong , Yang Dooyoung , Sung Hyeokjae l'Yee and Yungkwon
Published: October 2002

In this paper we discuss in detail the mechanism for hot-carrier induced circuit degradation in actual 64Mb DRAM (dynamic random access memory), by investigating the DRAM specification parameter shift due to transistor aging in each of the constituent circuits. It was found that hot-carrier induced transistor aging of the circuit block does not directly affect the internal clock speed degradation, however, it does greatly reduces the design margin of a circuit which suffers from heavy loads. In addition, an in-depth study of the dynamic hot-carrier degradation behavior of N-channel transistors more common in actual VLSI circuits was carried out based on the alternating stress and charge pumping techniques.
Fabrication and Transport Properties of Silicon Quantum Wire Gate-All-Around Transistor
Authors: Morimoto Kiyoshi , Hirai Yoshihiko , Koichirou Yuki Koichirou Yuki , Kiyoyuki Morita Kiyoyuki Morita
Published: October 2002

A novel fabrication method of silicon quantum wire gate-all-around transistor (GAAT), in which the gate oxide and the gate electrode are wrapped around ultrafine silicon quantum wire, has been proposed. In order to verify one-dimensional (1D) subband effects, we have studied quantum transport in Si quantum wire GAAT with a width of 50 nm at 1.5 K in zero-magnetic field and in fields up to 10 T. Electrical population and magnetic depopulation of 1D subbands are clearly observed.
Extremely Large Amplitude Random Telegraph Signals in a Very Narrow Split-Gate MOSFET at Low Temperatures
Authors: Hiroki Ishikuro Hiroki Ishikuro , Takuya Saraya Takuya Saraya , Toshiro Hiramoto Toshiro Hiramoto , Toshiaki Ikoma Toshiaki Ikoma
Published: October 2002

We have observed very large amplitude (≈90%) random telegraph signals (RTS) near the pinch-off voltage at very low temperature (1.5 K) in a very narrow, short channel n-MOSFET fabricated by a split-gate technique on an silicon on insulator (SOI) substrate. This large amplitude of RTS can be explained by numerical calculation which takes the potential of the charged trap into account.
Substrate Engineering for Reduction of Alpha-Particle-Induced Charge Collection Efficiency
Authors: Yamashita Tomohiro , Komori Shigeki , Kuroi Takashi , Masahide Inuishi Masahide Inuishi , Hirokazu Miyoshi Hirokazu Miyoshi
Published: October 2002

Measurements of alpha-particle-induced charge collection efficiency (CCE) together with simulation analysis have been carried out for several types of substrates: a double well, a p-well in a p- epitaxial layer grown on p+ substrate (epi-substrate) and a p-well with a buried defect layer. As a result, the following have been clarified. CCE for the double well is low because the bottom n-layer acts as an effective electron absorber. CCE for the p-well in the epi-substrate increases with increase in the thickness of the epilayer because the potential difference between the heavily doped substrate and the lightly doped epilayer forms a barrier which prevents electrons from traveling into the substrate. Even for the p-well in a thin epilayer, CCE is comparable to that for the p-well in the conventional p- substrate. CCE for the p-well with a buried defect layer formed by high-energy and high-dosage ion implantation is as low as CCE for the double well because the carrier lifetime is short in the buried layer due to lattice defects.
Influence of N2O Oxynitridation on Interface Trap Generation in Surface-Channel p-Channel Metal Oxide Semiconductor Field Effect Transistors
Authors: Toshimasa Matsuoka Toshimasa Matsuoka , Shigenari Taguchi Shigenari Taguchi , Kenji Taniguchi Kenji Taniguchi , Chihiro Hamaguchi Chihiro Hamaguchi , Seizo Kakimoto Seizo Kakimoto , Keiichiro Uda Keiichiro Uda
Published: October 2002

The influence of N2O oxynitridation on hot-carrier-induced degradation of surface-channel p-channel metal oxide semiconductor field effect transistors was investigated. N2O oxynitridation reduces electron trapping due to the high barrier height for electron injection. N2O oxynitridation has little effect on electron and hole energies for interface trap creation. For drain avalanche hot electron injection, the role of a nitrogen-rich region as the diffusion barrier of hydrogen species is to reduce interface trap generation by chemical reaction between hydrogen atoms and Si3≡Si–H precursors at the Si/SiO2 interface. However, interface trap generation is enhanced by the existence of nitrogen atoms near the Si/SiO2 interface for channel hot hole injection. The enhancement of hole trapping may be due to a decrease in the compressive stress near the Si/SiO2 interface by nitrogen incorporation.
A High Performance p-Channel Transistor: β-MOS FET
Authors: Yoh Kanji , Koizumi Ryouji , Hashimoto Naotaka , Ikeda Shuji
Published: October 2002

We have fabricated a β (Bipolar Enhanced Transistor Action) MOS FET device which operates in combined FET and bipolar modes, while perfectly maintaining the MOSFET circuit configuration with extended operational voltage up to -4 volts due to gate-voltage-controlled base resistance of the parasitic lateral bipolar transistor. Three types of gate-to-substrate contact were investigated including ultrathin tunnelling barriers. The p-channel β-MOS FET showed dramatic improvements in transconductance by a factor of 4 while maintaining the same threshold voltage (≈-1 V) compared with conventional MOS structures. This result of 1.3 µm β-MOS FET is favorably compared with one tenth of a micron p-MOS FET.
Fabrication of P-Channel MOS TFT's on Rapid Thermal CVD Polycrystalline Silicon-Germanium Films
Authors: Lee Seo-Kyu , Kim Hyung-Geun , Chung Wook-Jin , Bong-Koo Kang Bong-Koo Kang , Ohyun Kim Ohyun Kim
Published: October 2002

P-channel metal-oxide-semiconductor (PMOS) thin-film transistors (TFT's) have been fabricated on rapid thermal chemical vapor deposition (RTCVD) polycrystalline silicon-germanium (poly-Si0.82Ge0.18) films for the first time. The transistors with a channel length of 1.5 µm exhibit good electrical characteristics. The device performance is degraded in proportion to oxygen content, based on measurements using secondary ion mass spectrometry (SIMS). After electron cyclotron resonance (ECR) plasma hydrogenation under optimal conditions, the density of trap states is markedly decreased in short-channel devices, resulting in relatively low leakage current (∼12.1pA/µm) and high field-effect hole mobility (∼13.4cm2/V·s).
Advanced Quality in Epitaxial Layer Transfer by Bond and Etch-back of Porous Si
Authors: Sato Nobuhiko , Sakaguchi Kiyofumi , Yamagata Kenji , Fujiyama Yasutomo , Jun Nakayama Jun Nakayama , Takao Yonehara Takao Yonehara
Published: October 2002

We report recent qualitative advances in bonding and etch-back of silicon on insulator (SOI) using structure-sensitive selective etching of porous Si. The defect density in the epitaxial layer grown on the porous Si is lowered to 3.5×102/cm2 by raising the H2 prebake temperature in conjunction with the “preinjection technique” in which a small amount of Si is supplied during the high-temperature H2 prebake prior to epitaxial growth. H2 annealing also gives a smooth SOI surface comparable to the bulk polished wafer. Improved thickness uniformity of ±1.8% is achieved using the single wafer processing epi-reactor. The electrical characteristics are evaluated by fabricating pn-junction diode.
Advantages of Ultra-Thin SIMOX/CMOS based on Well-Established 0.8 µm Mass-Production Technologies for Low Power 1 V Phase Locked Loop Circuits
Authors: Tsuboi Osamu , Warashina Suguru , Sukegawa Kazuo , Kawai Shinichi , Kawamura Seiichiro , Sekine Shinichi , Takada Keniji , Suzuki Hirokazu
Published: October 2002

This paper describes the various advantages of silicon on insulator (SOI) circuits when well-established 0.8 µm Complementary Metal Oxide Semiconductor (CMOS) mass-production technologies for ultra-low power 1 V phase locked loop (PLL) circuits are applied. From experiments on circuit operation, a parasitic capacitance of SOI is estimated about 20% reduced to bulk, and it is found that the most prominent advantage of SOI is 80% faster operation than bulk at low supply voltage due to less drain capacitance and less short channel effects of p-channel MOS field effect transistor (pMOSFET).
Analysis of Si–Ge Source Structure in 0.15 µm SOI MOSFETs Using Two-Dimensional Device Simulation
Authors: Arisumi Osamu , Matsuzawa Kazuya , Shigyo Naoyuki , Terauchi Mamoru , Akira Nishiyama Akira Nishiyama , Makoto Yoshimi Makoto Yoshimi
Published: October 2002

We describe the technological potential of the bandgap engineering technique involving a Si–Ge source structure in a fully-depleted SOI MOSFET to suppress the floating-body effect. The Si–Ge layer fabricated in the source region acts as an absorber for excess holes in the channel region. The detailed mechanism as well as the structure dependence in SOI MOSFETs with a gate length of 0.15 µm have been studied using a two-dimensional device simulation. It has been found that the improvement in B
V
ds is strongly dependent on the lateral position of the Si–Ge layer relative to the source-to-channel pn junction. It is further predicted that encroachment of the Si–Ge layer into the channel region achieves the maximum B
V
ds improvement. The B
V
ds improvement is predicted to reach 1.5 V if it proves possible to lower the energy barrier at the pn junction in the case where ΔE
g=0.2 eV.
Fabrication of Lead Iron Niobate Films on Si Substrate by Pulsed Laser Deposition
Authors: Xin-Rong Wang Xin-Rong Wang , Shou-Shan Fan Shou-Shan Fan , Qun-Qing Li Qun-Qing Li , Bing-Lin Gu Bing-Lin Gu , Xiao-Wen Zhang Xiao-Wen Zhang
Published: October 2002

Ferroelectric Pb(Fe1/2Nb1/2)O3 (PFN) films were heteroepitaxially grown on Si (100) substrates by pulsed laser deposition. The optimum conditions to form the (100) oriented PFN perovskite phase were at a substrate temperature of 700°C with an oxygen pressure of 200 mTorr. The Pb content in the target was found to be essential to the formation of the perovskite phase in PFN films. Heterostructures consisting of PFN/La0.5Sr0.5CoO3 (LSCO) films were prepared on Si (100) substrates to evaluate the dielectric and ferroelectric properties of the films. Ferroelectricity in these films was confirmed by the presence of hysteresis loops, with a remnant polarization of 0.2 µC/cm2 and coercive field of 5.12 kV/cm. The room-temperature dielectric constant measured at 10 kHz was 194 and the dissipation factor was 0.7.
Second-Harmonic Generation in Smectic A Phase of Ferroelectric Liquid Crystal Induced by Electroclinic Effect
Authors: Uto Kentaro Kobayashi , Svensson Masanori Ozaki , Bertil Helgee Bertil Helgee , Kent Skarp Kent Skarp
Published: October 2002

Second-harmonic generation (SHG) of ferroelectric liquid crystal (FLC) has been studied in the smectic A (Sm A) phase in 4'-(1-butoxycarbonyl-1-ethoxy)-3'-nitrophenyl 4-[4-(ω-alkenyloxy)phenyl]benzoate (1BC1ENPAPB) with large electroclinic (EC) effect and a large spontaneous polarization. Type I phase-matching has been observed in the angular dependence of SHG intensity in the Sm A phase. SHG intensity caused by the EC effect is proportional to the square of applied electric field, and it has been found that the effective optical coefficient is proportional to electric field.
Hydrogen Sensing with NaY Zeolite-Entrapped Copper Dicyanoanthraquinone Diimines
Authors: Chang Jun Shang , Lilian Kao Liu Lilian Kao Liu , Chong Mou Wang Chong Mou Wang
Published: October 2002

Intrazeolite copper dicyanoanthraquinone diimines were synthesized within NaY zeolite using a “ship-in-a-bottle” technique. IR absorption spectra confirmed the formation of Cu-DCNAQI in NaY. The compound material not only showed high stability against photocorrosion during IR irradiation but also exhibited remarkable sensitivity to hydrogen with negligible interference from exygen.
Characterization of Antenna Effect by Nondestructive Gate Current Measurement
Authors: Lin Horng-Chih , Chien Chao-Hsin , Huang Tiao-Yuan
Published: October 2002

A novel method is proposed for the effective characterization of plasma-charge-induced damage on thin gate oxides. We have found that the gate current measured at V

g
(gate voltage)= V

t
h
(threshold voltage) under a low drain bias ( e.g., 0.1 V) is a good indicator of the damage. Since the proposed method requires only low bias voltages, it does not cause additional damage to the devices. The proposed gate current measurement is also easy to incorporate to device measurement routines without an extra stressing step, and thus provides a simple and efficient damage indicator for studying plasma-charge-induced damage.
Magnetism and Magnetoresistive Properties in FexCu100-x Alloys Produced by Mechanical Alloying
Authors: Ueda Yuji , Ikeda Shoji , Satoshi Moriwaki Satoshi Moriwaki , Mizushi Matsuda Mizushi Matsuda
Published: October 2002

Metallic granular Fe

x

Cu100-
x

alloys with Fe concentration of x=10–90 are prepared by mechanical alloying (MA). The alloy structure, magnetoresistance (MR), and magnetism have been investigated for as-milled and annealed samples. After milling for 50 h, the samples consist of a supersaturated solid solution of single fcc phase over the wide Fe concentration range x=10–60. The magnetization of the as-milled samples deviates downward from a simple dilution law, decreases with decreasing x and vanishes at x≃20. The maximum MR ratio, under 15 kOe at room temperature, is 1.2% for the sample with x=28 annealed at 250° C for 1 h. The samples with x=18–28 show reentrant spin-glass-like behavior. However, the samples with x greater than 25 show ferromagnetic behavior at room temperature.
Single Longitudinal Mode Properties of External Cavity Tapered and Straight Broad-Stripe Lasers with Bandpass Filter
Authors: Hayakawa Toshiro , Yamanaka Fusao , Toshiaki Kuniyasu Toshiaki Kuniyasu , Toshiaki Fukunaga Toshiaki Fukunaga
Published: October 2002

The single longitudinal mode properties of external cavity broad-stripe lasers combined with bandpass filters have been investigated. With tapered amplifiers, the emission wavelength changes periodically as a function of the driving current due to shifting of the internal Fabry-Perot mode and the narrow bandwidth of the filter. In contrast, with straight amplifiers, the peak wavelength monotonically varies. This is due to changes in the transverse mode of straight amplifiers.
Scanning Tunneling Microscopy Study of Initial Growth of CaF2 and BaF2 on Si(111)
Authors: Sumiya Touru , Miura Tadao , Haruko Fujinuma Haruko Fujinuma , Shun-ichiro Tanaka Shun-ichiro Tanaka
Published: October 2002

Scanning tunneling microscopy (STM) has been used to investigate nucleation and initial growth in the heteroepitaxies of calcium fluoride ( CaF2) and barium fluoride ( BaF2) on Si(111) surfaces in situ. The fluoride depositions and the STM measurements are performed at a substrate temperature of about 400° C. STM images clearly show that a BaF2-deposited surface has a different morphology from that of CaF2-deposited surface. Preferential nucleation and island growth of BaF2 only occur at steps and domain boundaries on a Si(111)-7×7 reconstructed surface. On the other hand, CaF2 islands nucleate not only at steps and domain boundaries but also in domain-boundary-free regions of a Si(111) surface. We attribute the difference in the morphologies to the much higher mobility and diffusion length of a BaF2 molecule in comparison to those of a CaF2 molecule on a Si(111) surface at 400° C. We also report the first STM measurement of a (CaF2+BaF2)-coexisting surface at 480° C.
Interaction of Ga Adsorbates with Dangling Bonds on the Hydrogen Terminated Si(100) Surface
Authors: I. Lutwyche Tomihiro Hashizume , Satoshi Watanabe Satoshi Watanabe , Ken Nakajima Ken Nakajima , Toshio Nishi Toshio Nishi , Yasuo Wada Yasuo Wada
Published: October 2002

Adsorption of Ga on the hydrogen terminated Si(100)–2×1–H surface has been investigated by scanning tunneling microscopy (STM). We have found that the thermally deposited Ga atoms preferentially adsorb on the hydrogen-missing dangling bonds and on the surface impurities. We desorb hydrogen atoms by the STM current and fabricate atomic-scale dangling-bond wires, in the similar way as was reported by Lyding et al. [Appl. Phys. Lett. 64 (1994) 2010]. In order to fabricate more detailed dangling bond structures, several methods of manipulating (detaching, attaching and moving) the individual hydrogen atoms are tested. We are able to thermally deposit Ga atoms on a dangling-bond wire and fabricate an atomic-scale Ga wire on the Si surface.
Heat Capacity and the Structure of Chalcogenide Glasses by Modulated Differential Scanning Calorimetry (MDSC)
Authors: Kasap Safa O. , Maeda Tomas Wagner
Published: October 2002

The recent novel temperature-modulated differential scanning calorimetry (MDSC) technique has been applied to characterize the thermal properties of Te

x

Se100-
x

, As

x

Se100-
x

and Ge

x

Se100-
x

chalcogenide glasses in the glass transition region. All samples in this work were given the same thermal history. The reversing and non-reversing heat flows through the glass transformation region during both heating and cooling schedules were measured. The values of the relaxation enthalpy ΔH and heat capacity C
p which characterize the thermal events in the glass transition region, were determined. The ΔH vs composition behavior shows a linear increase of ΔH with Te in Se100-
x

Te

x

glasses whereas for the Se100-
x

As

x

and Se100-
x

Ge

x

glasses ΔH evinces maxima at 16.6, 28.5, 40 at% As, and maxima at 20, 33, 40 at% Ge, respectively. The C
p vs composition plot shows a linear decrease of C
p with Te in Se100-
x

Te

x

glasses. In contrast, C
p vs composition behavior for the Se100-
x

As

x

and Se100-
x

Ge

x

glasses, reveal minima at 16.6, 28.5, 40 at% As and maxima at 20, 33, 40 at% Ge respectively. We compare our MDSC results with previously published works on glass transition in these glasses and discuss the results in terms of recent structural models for chalcogenide glasses.
Influence of Optical Purity on the Smectic-Cβ
* Phase of Antiferroelectric Liquid Crystals
Authors: Sako Teiyu , Kimura Yasuyuki , Hayakawa Reinosuke , Okabe Nobuhiro , Suzuki Yoshiichi
Published: October 2002

The Smectic- Cβ
* (SmCβ
*) phase, which appears between the SmA and SmC
A

* phases in an optically pure liquid crystal of MHPOBC, has been studied by means of simultaneous measurements of the dielectric constant ε and the electroclinic coefficient κ under a dc bias electric field. The result of electroclinic coefficient measurement shows that the SmCβ
* phase is obviously different from the SmC* phase and can be considered as a ferrielectric phase. From the simultaneous measurement of ε and κ, we can observe the difference in the phase transition behaviors between pure and slightly racemized MHPOBC samples and confirm that the decrease of optical purity causes the change from the SmCβ
* phase to the SmC* phase.
High Pressure High Temperature Steam Oxidation Poly Buffer LOCOS (HP-HTPBL) Field Isolation Process for Reduced Encroachment and Low Stress
Authors: Deleonibus Simon , Martin François , Kim Sang S. , Emami Alan , Florin Brigitte , Michel Heitzmann Michel Heitzmann , Charles Leroux Charles Leroux
Published: October 2002

The characterization of High Pressure-High Temperature Poly Buffer LOCOS (HP-HTPBL) isolation for 0.2 µ m design rules Non Volatile Memories is presented. Reduced bird's beak and improved charge to breakdown (Q
bd) are obtained by combining High Pressure (25 atmospheres) 1100° C steam oxidation and 30° C/min ramp-up and 12° C/min ramp-down temperature rates. The fast temperature ramp-up inhibits the crystallization of the amorphous silicon (a-Si) buffer layer into large grain and limits the grain boundaries oxygen diffusion during the field oxidation process. Low warpage variations are obtained on 200 mm diameter wafers by the reduction of the cumulative oxidation induced stress.
Slot Antenna Coupled Thin-Film YBCO Josephson Mixers
Authors: Nozue Takashi , Hasegawa Akihisa , Yamashita Yoshizumi Yasuoka
Published: October 2002

Antenna coupled thin-film Y1Ba2Cu3O7-
x

Josephson mixers, consisting of a slot antenna on a fused quartz substrate and a YBCO Josephson junction on a MgO substrate, were fabricated and mixing experiments were carried out in the 50 GHz millimeter wave region. The mixing signal (IF output) obtained using the antenna coupled Josephson mixer was 12 dB greater than that obtained using the mixer without the antenna.
Electrical Feedback Using a Saturable Absorber as an Internal Photodetector in Self-Pulsating Two-Section Laser
Authors: Mitsuaki Shimizu Mitsuaki Shimizu
Published: October 2002

The self-pulsating frequency of a two-section semiconductor laser was stabilized by a new compact electrical feedback method. The electrodes of the saturable absorber and the gain region were connected with an alternating current (AC) coupling circuit. Because the saturable absorber serves as a detector of light power in the lasers, it can be used to provide feedback from the saturable absorber to the gain region. The delay time of feedback depended mainly on the length of the circuit and determined the self-pulsating frequency. Pulse narrowing was also observed, and short optical pulses with 30 ps width were obtained.
Proposal for Generation of a Coherent Pulse Ultra-Broadened from Near-Infrared to Near-Ultraviolet and Its Monocyclization
Authors: Mikio Yamashita Mikio Yamashita , Hiroyasu Sone Hiroyasu Sone , Ryuji Morita Ryuji Morita
Published: October 2002

An approach for generation of an ultrabroad-band optical pulse (∼550 THz width) is proposed, which is based on mutual induced phase modulation of three synchronized femtosecond pulses in a short fiber. These pulses having equidistant carrier frequencies and constant carrier-phase differences are obtained from the fundamental (ω01), the second-harmonic (2ω01) and the second-harmonic-pulse pumped parametric (3ω01/2) waves. These are generated under the phase-matched, frequency-conserved and gain-maximized conditions by one common femtosecond pulse. Computer analysis shows that chirp of the composite wave at the fiber output can be compensated for by a spatial phase modulator and a 1.76-cycle pulse is generated.
Microstrip Gas Chamber for X-Rays and Neutrons
Authors: Yasushi Hayakawa Yasushi Hayakawa , Yutaka Maeda Yutaka Maeda
Published: October 2002

The prototype of a microstrip gas chamber (MSGC) has been constructed and tested as an X-ray detector. The calculation of the electric field around microstrips suggests that the process of gas amplification, which is realized with a smaller potential difference than that of a multiwire proportional chamber (MWPC), is unique. The result, however, shows that the MSGC operates like a conventional MWPC and has energy resolution better than 30% in terms of full width at half-maximum at 5.9 keV. In addition, this gas chamber can be used as a neutron detector by filling it with 3He and CF4 gases.
Effects of Growth Temperature on Solid Incorporation of AlAs1-
xSbx Using Tertiarybutylarsine as Arsenic Source Precursor
Authors: Wei-Kuo Chen Wei-Kuo Chen , Jehn Ou Jehn Ou , Ching-Hao Hsu Ching-Hao Hsu
Published: October 2002

We have investigated the effects of growth temperature on the solid incorporation of AlAsSb epilayers grown by metalorganic vapor-phase epitaxy using TMAl, TBAs and TMSb as source precursors. The solid incorporation of AlAsSb was found to be strongly affected by the pyrolysis reactions and kinetics of the source precursors, in particular, TMAl and TBAs. Our experimental results indicated that the Al incorporation efficiency increases with the growth temperature and saturates at temperatures above ∼625°C. On the other hand, the growth behavior of As is anomalous: the As incorporation efficiency increases initially with growth temperature, and decreases monotonously at temperatures above ∼550°C. The reduced As incorporation efficiency at high temperatures may be closely related to the β-elimination process of TBAs, and to the formation of adducts in the gas phase.
Direct Determination of Bare Confinement Potentials in AlGaAs/GaAs Split-Gate Quantum Wires by Far-Infrared Spectroscopy
Authors: Wang Shinan , Yamanaka Koji , Hirakawa Kazuhiko , Noguchi Mitsuhiro , Ikoma Toshiaki
Published: October 2002

We have investigated the far-infrared (FIR) photoresponse of the magnetoresistance of the quasi-one-dimensional electron systems in AlGaAs/GaAs split-gate single quantum wire (QWR) structures. It was found that the QWR structures exhibit photoinduced resistance change due to resonant FIR absorption between the magnetoelectric subbands. From a spectroscopic analysis based on the generalized Kohn's theorem, the lateral bare confinement potential, V
b, in the split-gate QWR structures has been determined directly. The V
b obtained is in good agreement with a theoretical prediction based on simple electrostatics, indicating that FIR spectroscopy is a suitable tool for characterizing the electronic structures in quantum wire structures.
Chemical and Structural Characterization of Cu(In,Ga)Se2/Mo Interface in Cu(In,Ga)Se2 Solar Cells
Authors: Wada Takahiro , Kohara Naoki , Takayuki Negami Takayuki Negami , Mikihiko Nishitani Mikihiko Nishitani
Published: October 2002

Interfaces between the Cu(In,Ga)Se2 (CIGS) absorber and the Mo back contact in CIGS solar cells were investigated by secondary ion mass spectroscopy (SIMS) and analytical transmission electron microscopy (TEM). The solar cell with MgF2/ITO/ZnO/CdS/CIGS/Mo/glass structure exhibited an efficiency of over 15%. In the SIMS depth profile, the Se intensity had a peak at the CIGS/Mo interface. Cross-sectional TEM observation showed that there were two layers at the interface. One was a MoSe2 layer and the other was an amorphous layer. The thickness of the interface layers depends on the deposition conditions of the Mo layers.
An Application of Polyphenylsilsesquioxane (PPSQ) to Organic Anti Reflective Coating (ARC)
Authors: Minami Shintaro , Etsushi Adachi Etsushi Adachi , Hiroshi Adachi Hiroshi Adachi
Published: October 2002

A Polyphenylsilsesquioxane (PPSQ) is an inorganic polymer that has a cis-syndiotactic double chain structure [J. F. Brown, Jr.: J. Polym. Sci. 1C (1963) 83]. By mixing a dye that strongly absorbs the i-line with PPSQ in solution, PPSQ obtained by means of conventional spin-coating can be used as an anti reflective coating (ARC). Since the PPSQ ARC has a large absorbance k value, its reflectance depends little on its thickness, and the thickness uniformity of PPSQ film is superior even if it is formed by spin coating. By using this PPSQ ARC, no reflective notching or linewidth variation of the photoresist pattern are observed.
Order Re-Equilibration Kinetics within the B2 and DO3 Phases of Fe3Al
Authors: Byungwoo Park Byungwoo Park
Published: October 2002

The re-equilibration kinetics of short-range order within the B2 disordered phase, and of short- and long-range order within the DO3 ordered phase have been studied in Fe3Al with in situ X-ray scattering. For quenches within the B2 phase, the diffuse intensity I
S(t) and correlation length ξ(t) relax exponentially at the same rate. For shallow quenches within the DO3 phase, the long-range-order Bragg intensity I
L(t) as well as I
S(t) and ξ(t), all relax exponentially but with different rates. For deep quenches, however, nonexponential behavior of I
S(t) and ξ(t) is observed, consistent with formation of new long-range order from fluctuations.
Measurement of the Steady-State Minority Carrier Diffusion Length in a HgCdTe Photodiode
Authors: Jung Han , Hee Chul Lee Hee Chul Lee , Choong-Ki Kim Choong-Ki Kim
Published: October 2002

A new method is reported for estimating the steady-state effective minority carrier diffusion length. The diffusion length is determined by measuring photocurrents which decrease exponentially with the distance between the junction edge and the region into which environmental infrared light penetrates. The region exposed to infrared radiation can be defined using an optical shadow mask. Using this method, the steady-state effective minority carrier diffusion length of photodiodes fabricated on p-type bulk Hg0.7Cd0.3Te was determined to be 19 µ m at all points on the wafer.
Beam Smoothing in a Passive Q-Switched Laser with an Additional Stimulated Brillouin Scattering Output Coupler
Authors: Kim Hyun Su , Han Ki Gwan , Kim Nam Seong , Yun Sup Shin Yun Sup Shin , Hong Jin Kong Hong Jin Kong
Published: October 2002

We report a simple method of improving the spatial profile of a passive Q-switched Nd:glass laser. In this method, a stimulated Brillouin scattering (SBS) cell has been used as an additional output coupler. The resultant spatial profile of the beam transmitted through the SBS cell has a super-Gaussian-like shape. Furthermore, the single-pulse operating range could be extended to a pumping level higher than that previously known as two- or three-pulse regions in conventional passive Q-switched lasers.
Fabrication of Proton-Exchanged High-Index LiNbO3 Waveguides Using m-Toluic Acid
Authors: Chi-Yen Shen Chi-Yen Shen , Shuming Tong Wang Shuming Tong Wang
Published: October 2002

High-index optical waveguides have been fabricated from lithium niobate ( LiNbO3) using a simple proton-exchange process. In this study, proton-exchanged planar optical waveguides have been fabricated from z-cut LiNbO3 using a new proton source: m-toluic acid. These waveguides were characterized optically and the refractive index was found to vary with depth of waveguides. The variation of the refractive index exhibited a graded index profile with the maximum surface index change Δn = 0.14 measured at a wavelength of 0.633 µ m. The diffusion constant D
o and the activation energy Q for the proton-exchange process were measured to be 2.35×108 µ m2/h and 75.63 kJ/mol, respectively.