bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Properties of Ag(AlxGa1-x)S2 Crystals by Iodine Transport Method
Authors: Nozomu Tsuboi Nozomu Tsuboi , Yasunari Hashimoto Yasunari Hashimoto , Masaki Kurasawa Masaki Kurasawa , Satoshi Kobayashi Satoshi Kobayashi , Futao Kaneko Futao Kaneko
Published: October 2002

The growth of chalcopyrite Ag(Al
x
Ga1-x
)S2 crystals is demonstrated in the entire alloy composition range using the conventional iodine transport method. The composition of the grown crystals corresponds to that of starting materials. With increasing x, lattice constants decrease, following Vegard's law. The vibration modes for Raman scattering lines are assigned on the basis of the reported AgGaS2 data. The compositional dependence of the A1 mode spectrum is discussed in comparison with that for Cu–III–VI2 compounds. Two bands observed in photoluminescence excitation spectra for a dominantly deep emission at 77 K correspond to band-to-band transitions, which are related to the uppermost valence band and the lower two closed valence bands. The changes in photon energies of these photoluminescence excitation bands indicate an increase in the energy gap from 2.7 eV to approximately 3.6 eV with x. The spectral broadening of the A1 mode line and the two photoluminescence excitation bands around x=0.5 is considered to be due to the clustering effect.
Epitaxial Growth of GaN on LaAlO3(100) Substrate by RF Plasma Assisted Molecular Beam Epitaxy
Authors: Lee Jeoung Ju , Kang Kwang Yong , Park Young Sin , Yang Chang Soo , Kim Hyeon Soo , Kim Kun Ho , Kang Tae Won , Park Sung Ho , Lee Jeong Yong
Published: October 2002

About 0.4-µm-thick GaN films were epitaxially grown on a LaAlO3(100) substrate by rf plasma assisted molecular beam epitaxy. The growth mode was monitored by reflection high-energy electron diffraction and the crystalline quality of the GaN films was characterized by X-ray diffraction and transmission electron microscopy. The matching face relationship between GaN and the LaAlO3(100) substrate was [0001]GaN ∥[100]LaAlO3 and [0110]GaN ∥[011]LaAlO3, and a lattice mismatch of ∼3% for the [011] plane was estimated.
Advanced Detection of Initial State of Iron Rust Based on Dual-Mode Sensing of a Touch-Type Corrosion Sensor with Magneto Supply
Authors: Yonemoto Naruto , Shida Katsunori
Published: October 2002

Some nondestructive diagnostic methods, including various types
of corrosion sensors, have been investigated. Under these conditions,
a new sensor structure that is composed of a pair of electrodes and a
magneto supply is proposed. Dual-mode sensing, surface-mode sensing
and penetration-mode sensing, based on two different characteristics
of the monostructural sensor are realized by changing the direction of
the magnetic field. The sensor, in the surface mode with a large
impedance, detects first the initial state of iron rust, and then the
corrosion state of the iron rust which was detected in the surface
mode is diagnosed in the penetration mode with high precision. As a
result, an advanced instrumentation of the touch-type corrosion sensor
using dual-mode sensing is anticipated.
Comparison of Growth of Laminar Flows in Capillary: Poiseuille Flow, Electroosmotic Flow and Electroosmotic Circulation
Authors: Osuga Toshiaki
Published: October 2002

Growth of electroosmotic circulation (EOC) of a liquid in a closed capillary, which is generated after the
application of an electric field between the two
electrodes which cover the ends of the silica
capillary, is examined numerically. The applied
electric field accelerates the excess cations in the
electric double layer on the inner surface of the
capillary. The occurrence of collisions between the
accelerated cations and the neutral molecules induces
electroosmotic flow (EOF). A forward flow, caused by
the EOF, initiates the EOC. The EOC generates a
uniform cross-sectional force to create a return flow
for conserving zero total flux, and approaches a
steady parabolic flow profile, which is similar to the flow profile of the Poiseuille flow. Flow spectra
reveal that the forward and return flows enhance each
other under zero total flux and accelerate the growth
of the EOC, which is more rapid than that of the EOF and the
Poiseuille flow.
Investigation of Pulsed Laser Removal of Cr and MoSi Film on a Quartz Substrate
Authors: Chiba Akira , Suzuki Kazuhito
Published: October 2002

Cr and MoSi film removal from a quartz substrate was investigated using a Nd:YAG laser
repair system with a wavelength of 532 nm and pulse duration of 4 ns. Characteristics of the
debris, removal size, and transmittance were clarified from the
results of scanning electron microscope (SEM) observation and
optical measurements. The debris resulting from Cr and MoSi removal consisted of spherical
particles and pulverized powder, respectively. The difference in removal size between Cr and
MoSi was consistent at about 200 nm. In order to obtain the optimum optical transmittance, it
was found that the laser energy required for Cr removal is 1.45 times higher than that required
for MoSi removal. An approximate formula for estimating the actual laser energy required was
proposed. The actual laser energy was estimated to be 1/500 in comparison with the operational
energy measured using an in-house power monitor. An ablation model for the removal
mechanism based on melting and vaporization was constructed. The saturated formula was in
agreement with the results of experiments.
Optical Absorption and Electrical Conductivity of Amorphous Carbon Thin Films from Camphor: A Natural Source
Authors: Mominuzzaman Sharif Md. , Krishna Kalaga Murali , Soga Tetsuo , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

Thin films of carbon have been deposited on n-type single-crystal silicon and quartz substrates by simple ion beam sputtering of camphoric carbon, obtained from camphor, a natural source. Optical absorption coefficients of 104–105 cm-1 have been obtained for the as-deposited and annealed films and the absorption coefficient increased upon annealing. The optical band-gap energy of the as-deposited camphoric carbon thin film derived from optical absorption measurements is 0.5 eV. Effects of annealing on various optical and electrical properties are studied, in light of the semiconducting nature of these films, through the electrical conduction mechanism. The results obtained are discussed and compared with the literature.
Effective Segregation Coefficient of Tellurium in ZnSe1-xTex and BeyZn1-ySe1-xTex Bulk Crystals Grown Using Traveling Solvent Method
Authors: Maruyama Kenji , Suto Ken , Nishizawa Jun-ichi
Published: October 2002

Effective segregation coefficient of tellurium in ZnSe1-x
Te
x
and Be
y
Zn1-y
Se1-x
Te
x
bulk crystals was evaluated. ZnSe1-x
Te
x
and Be
y
Zn1-y
Se1-x
Te
x
bulk crystals were grown using the traveling solvent method with tellurium solution. The growth rate was 3 mm/day at a peak temperature of 1047°C. ZnSe1-x
Te
x
mixed crystals contain tellurium from 1.2 to 6.5 at.% (0.02<x<0.13). Be
y
Zn1-y
Se1-x
Te
x
bulk mixed crystals contain tellurium from 1.8 to 19.5 at.% and beryllium from 0.02 to 5.0 at.% (0.03<x<0.39, 0.0004<y<0.10). Tellurium effective segregation coefficient was k=0.55 ±0.15 for ZnSe1-x
Te
x
and was k=0.6 ±0.4 for Be
y
Zn1-y
Se1-x
Te
x
. We considered that these values were slightly less than unity due to the atomic sizes and the electronegativity.
Resonant Raman Effect on a CuGaSe2 Crystal Grown by the Traveling Heater Method
Authors: Kazuki Wakita Kazuki Wakita , Takayuki Miyazaki Takayuki Miyazaki , Yasuhiro Kikuno Yasuhiro Kikuno , Souichi Takata Souichi Takata , Nobuyuki Yamamoto Nobuyuki Yamamoto
Published: October 2002

Resonant Raman scattering phenomena in the case of CuGaSe2 crystals grown by the traveling heater method have been investigated.
Seven resonant Raman peaks which are assigned to one A1, one B2(L) and five E(L) modes, have been observed over a wide excitation energy range (1.54–1.66 eV).
The enhancement of these Raman peaks is due to incoming resonance mediated by the donor–acceptor pair transition states which are observed as a luminescence peak.
The breakdown of the Raman selection rule is attributed to the resonance effect.
Temperature dependence of Raman intensity also suggests that the transition states of the donor–acceptor pair act as intermediate states of the resonant Raman scattering.
Band Line-up of InAsP/InAlGaAs Quantum Well
Authors: Anan Takayoshi , Nishi Kenichi , Tokutome Keiichi , Sugou Shigeo
Published: October 2002

A band line-up of InAs0.45P0.55/In0.53(Al
x
Ga1-x
)0.47As heterojunction was investigated.
Type-I and type-II band line-ups were obtained according to the Al relative
composition x of InAlGaAs. This band line-up variation can be explained by
assuming the conduction band discontinuity of InAsP/InP to be 0.35. A large
conduction band discontinuity with type-I band line-up can be obtained with an Al
relative composition x larger than 0.6 in this material system, which is promising for
the multi-quantum well structure of 1.3-µm lasers with good temperature
performance.
Artificial Control of Spin Order and Magnetic Properties in LaCrO3–LaFeO3 Superlattices
Authors: Ueda Kenji , Tabata Hitoshi , Kawai Tomoji
Published: October 2002

Magnetic properties have been artificially controlled in LaFeO3–LaCrO3 superlattices by
arranging the atomic order of B site ions with changing the stacking direction and
periodicity. When Fe and Cr layers are atomically stacked along the
<111> direction,
ferromagnetism appears, as shown in our previous study. In the case of the
superlattices formed along the <100> direction, on the other hand, an antiferromagnetic
property appears and the Neel temperatures systematically change from 250 K to >400 K, corresponding
to the stacking periodicity. Although the total numbers of Fe and Cr
ions are the same in (111) and (100) stacking, quite a different magnetic character can
be created in the artificial superlattices.
Magneto-Optical Spectra in Co/MgO, Ni/MgO, Co/Ag and Ni/Ag Multilayers
Authors: Sato Hideki , Miyazaki Terunobu
Published: October 2002

We investigated magnetization and magneto-optical spectra in Co/MgO, Ni/MgO, Co/Ag and
Ni/Ag multilayers. All samples were prepared by magnetron sputtering. Crystal structures were
determined by a small or middle angle X-ray diffraction pattern. More than four superlattice peaks
were observed in all multilayers including MgO layers. Sharp superlattice peaks were observed in all
multilayers including Ag layers. Magnetization decreases with a smaller ferromagnetic layer thickness
in both Ag and MgO systems at room temperature. The same tendency was observed at 5 K.
However, the results in the magneto-optical spectra show a contrast between MgO systems and Ag
systems. The shape of the off-diagonal element of the conductivity
tensor (ωσ
x
y
) changes drastically
with the ferromagnetic layer thickness in MgO systems. However, the shape of the tensor ωσ
x
y

does not depend on the ferromagnetic layer thickness in Ag systems. This contrasting result reflects
the difference of the effect of interfaces on electrons in the ferromagnetic layers between insulating
MgO and metal Ag.
Transverse Biased Initial Susceptibility Measurements of Magnetization Reversal in Fe/MgO(100) Thin Films
Authors: Contreras Carmen , Menéndez José L. , Cebollada Alfonso , Calleja Javier F.
Published: October 2002

Transverse biased initial susceptibility (TBIS) measurements
were performed on Fe(100)/MgO(100) thin films, using a magnetooptical
Kerr effect system. A peak detected in the TBIS curve when the
magnetic field is applied along one of the easy axes, corresponding to
a small step in the hysteresis loop, is associated with the uniaxial
in-plane anisotropy superimposed on the crystalline biaxial. We proved
that TBIS is a suitable and sensitive technique for the study of this
phenomenon, and provides an accurate description of the magnetization
reversal process.
A Simulation of Magneto-Optical Signals in Near-Field Recording
Authors: Saito Kimihiro , Nakaoki Ariyoshi , Kaneko Masahiko
Published: October 2002

The diffraction from two-dimensional magneto-optical marks has
been calculated using the plane wave expansion method and the Fourier
modal method. The modulation transfer function (MTF) in near field
magneto-optical recording has been simulated for the first time on the
basis of the strict vector diffraction theory. The simulated result
proved that the magneto-optical signal is reduced by only 3 dB at
a spatial frequency of NA/λ, for an air gap of 50 nm between a solid
immersion lens with an effective numerical aperture (NA) of 1.5 and a
magneto-optical disk surface.
Theoretical Investigation of Charge-Up Dynamics in Teflon Film Induced by Electron Beam
Authors: Palov Alexandre , Fujii Haruhisa , Hiro Sanju
Published: October 2002

A method for describing charge-up dynamics in Teflon films
induced by electron beams from a microscopic viewpoint is
proposed. The physical model of the ≈1 eV–35 keV electron scattering
in the insulating polymer has been used to calculate the average
charge distribution inside Teflon films. The electric field and
potential as a function of the injection time have been calculated
from Poisson's equations. The relaxation of the charge density under
the action of its own electric field has not been considered in the
present method. The calculated dynamics of the surface potential is in
good agreement with available experimental data.
Pt and RuO2 Bottom Electrode Effects on Pb(Zr,Ti)O3 Memory Capacitors
Authors: Min Jeong Young Park , Il Moon Sang , Won Jeong Kyu , Hoon Kim Sung , Tae Song Joon , Junsin Yi Junsin Yi
Published: October 2002

This study examines the effects of bottom electrodes for metal ferroelectric metal (MFM) capacitor applications. We investigated the following parameters of bottom electrodes and Pb(Zr0.53Ti0.47)O3 (PZT) thin films: substrate temperature, rf power, gas flow rate, Ar/O2 ratio, electrode material, and post-annealing effect. Bottom electrodes grown at 300°C for Pt and 200°C for RuO2 exhibited a film resistivity of 10-4 Ω·cm, had a surface roughness of approximately 55 Å and a preferred crystal orientation. Rapid thermal annealing (RTA) treatments on a Pt electrode at 600°C for 30 s improved the resistivity to 5×10-6 Ω·cm and generated the (111) preferred crystal orientation. PZT films exhibited a strong PZT (101) peak for an optimized Pt bottom electrode and (111), (200), (112) planes without preferred PZT orientations for the RuO2 electrode. A well-fabricated Pd/PZT/Pt capacitor showed a leakage current density in the order of 6×10-5 A/cm2, a dielectric constant (ε
r) of 365, a remanent polarization (P
r) of 27 µC/cm2, and a coercive field (E
c) of 50.5 kV/cm. This paper discusses the bottom electrode properties as well as their recommended conditions in memory device applications of thin-film PZT capacitors.
Dielectric and Electrical Characteristics of Titanium-Modified Ta2O5 Thin Films Deposited on Nitrided Polysilicon by Metalorganic Chemical Vapor Deposition
Authors: Chang Chich Shang , Wu Tai Bor , Shih Wong Cheng , Chao Lan Lin
Published: October 2002

Titanium-modified tantalum oxide thin films with a composition
of (Ta2O5)0.922–(TiO2)0.078, and pure
Ta2O5 thin films of 12 nm thickness were prepared on a
nitrided poly-Si electrode by liquid source delivery metalorganic
chemical vapor deposition at 390°C. The effective dielectric
constant of the Ti-modified Ta2O5 thin films is higher than
that of the pure Ta2O5 thin films whether they were
crystallized or not. The highest value of the effective dielectric
constant is 30.2 for the Ti-modified Ta2O5 thin films after
being subjected to rapid thermal oxygen annealing (RTO) at
800°C for 30 s, but that of the pure Ta2O5 is only
22.4 under the same heat treatment conditions. Moreover, the former
also has a high and stable insulating characteristic against bias
voltage, i.e., a low leakage current of 1×10-8 A/cm2
can be maintained at 2.5 MV/cm after RTO at 850°C for
90 s. However, that of pure Ta2O5 only reaches 1×
10-7 A/cm2 under the same treatment conditions. The
relationship of current versus time (I–t) measured at room
temperature also reveals the superior insulating property of
Ti-modified Ta2O5 compared to that of pure Ta2O5
thin films. An excellent leakage current characteristic along with
high capacitance suggests that the Ti-modified Ta2O5 thin
film is a more promising material than the pure Ta2O5 film
for use in the fabrication of capacitors for G-bit dynamic random
access memories.
Sintering Behavior and Microwave Dielectric Properties of (Ca, La)(Ti, Al)O3 Ceramics
Authors: Moon Jong Ha , Jang Hyun M. , Park Hyun S. , Shin Jong Y. , Kim Ho S.
Published: October 2002

The dielectric and sintering properties of (1-x)CaTiO3–xLaAlO3 were investigated. The
greater the amount of LaAlO3, which has a lower sintering temperature than CaTiO3, the
higher the relative density is obtained. As x increased in (1-x)CaTiO3–xLaAlO3, the following
phase transformation occurred: orthorhombic (x ≤0.4) →pseudocubic (x=0.5) →rhombohedral (x≥0.6).
The microwave dielectric properties of
ε
r=37, Q·f
0=47,000 (at 7 GHz), and τf=5 ppm/°C were obtained at 0.65CaTiO3–0.35LaAlO3. Also, various compounds of low melting point were added to 0.5CaTiO3–0.5LaAlO3 in order to decrease
the sintering temperature. When 3 wt% of 0.97Bi2O3–0.03Al2O3 or 0.76Bi2O3–0.24NiO as
sintering additive was added, the sintering temperature was lowered from 1600°C to 1450°C,
and the relative dielectric constant (ε
r) and the temperature coefficient of the resonant
frequency (τf) were not changed, whereas the Q·
f
0 values were lowered by about 15% and 34%, respectively.
Near-Infrared Photoluminescence in Mo-Doped Single Crystals of CuAlS2
Authors: Takao Nishi Takao Nishi , Naohiro Ishibashi Naohiro Ishibashi , Yuji Katsumata Yuji Katsumata , Katsuaki Sato Katsuaki Sato
Published: October 2002

Near-infrared photoluminescence (PL) spectra were measured at 6 K in single crystals of CuAlS2 doped with different amounts of Mo. A fine-structure PL emission was observed around 1,600 nm (0.775 eV) in both lightly and heavily doped crystals. The emission was tentatively assigned to the ligand-field transition in 4d3-manifold of Mo3+ ions taking into account the reported PL spectrum in Nb2+ (4d3)-doped GaAs. On the other hand, a broad emission band around 1,500 nm (0.826 eV) was only observed in heavily-doped crystals and was tentatively assigned to an intra-center transition of the Mo2+–X complex.
Pulse Crosstalk Analysis of Bondwires in High-Speed Plastic Packages
Authors: Yun Sang-Ki , Lee Hai-Young
Published: October 2002

Pulse transmission integrity and crosstalk of bondwires buried
in plastic packages are analyzed using the method of moments and the
Fourier transform algorithm, showing that the quasi-static crosstalk
model of simulation program with integrated circuit emphasis (SPICE)
is inappropriate for designing high-speed plastic packages. Plastic
packaging material, which increases the self and mutual capacitances,
is found to be helpful for pulse transmission integrity due to the
dielectric compensation effect. However, it is also observed that the
plastic material increases the pulse crosstalk due to the
radiation-enhanced mutual coupling effect. By investigating the
geometrical and material dependence of the pulse transmission and
crosstalk, we observe that the radiation-enhanced coupling effect is
significant for most typical bondwire geometries in common plastic
molding materials. These calculation results can be effectively used
for designing plastic-mold packages of high-speed digital integrated
circuits and monolithic radio frequency integrated circuits (RFICs).
Response of Longitudinal Waves Normally Impinging upon Layered Chiral Media
Authors: Ro Ruyen
Published: October 2002

Chiral materials are noncentrosymmetric due to handedness in
their microstructures. The elastic field behavior in a chiral medium
can be easily described using governing equations and constitutive
relations for noncentrosymmetric, isotropic micropolar materials. In
this study, reflection and transmission characteristics of layered
chiral media bounded by two semi-infinite achiral media for normally
incident longitudinal waves are investigated. A matrix-propagating
method for determining the scattering matrix of layered chiral media
is elucidated. Scattering characteristics of four-layer chiral media
are simulated and verified.
Evaluation and Countermeasures of Convective Heat Transfer on Thermal Conductivity Measurement Using the Peltier Effect and Application to Supercritical CO2
Authors: Chen Zai-hua , Tozaki Ken-ichi , Nishikawa Keiko
Published: October 2002

In the previous paper, the present authors reported a newly developed method of thermal conductivity measurement for fluids using a thermoelectric module. It was very simple and effective for samples in supercritical states. However, the countermeasures against thermal perturbation were insufficient. In the present work, some improvements have been made on the apparatus to eliminate thermal convection. The convective heat transfer effect on the measurement has been evaluated by varying the temperature difference across the sample layer. It has been found that the convection-free conductivity for critical and supercritical fluids can be determined by extrapolation of the temperature difference to 0. The thermal conductivity of supercritical CO2measured by the improved method is presented, including the states near the critical point.
Theoretical Estimation of the Energy Differences among OH-, F-, and H-terminations of the Si Surface
Authors: Tadatsugu Hoshino Tadatsugu Hoshino , Yasushiro Nishioka Yasushiro Nishioka
Published: October 2002

Energy changes during the conversion reaction among OH-, F-, and H-terminated Si surfaces have been evaluated by first-principles calculations with the density functional theory and the reaction field method for solvent effect. First, the reaction paths for the conversion of surface terminating species were examined in terms of the interactions with HF or H2O and, next, the potential energy curves were estimated, incorporating the effect of the solvent. It was suggested that the OH-termination is easily converted into the F-termination and the reverse reaction also possibly occurs at room temperatures, whereas the conversion between the H- and OH-terminations is not probable. The replacement of F by H is not favorable, and instead, Si etching would be required for the generation of the H-terminated surface.
Target for a Pb(Zr,Ti)O3 Thin Film Deposited at a Low Temperature Using a Quasi-Metallic Mode of Reactive Sputtering
Authors: Je-Deok Kim Je-Deok Kim , Shinya Kawagoe Shinya Kawagoe , Kimihiro Sasaki Kimihiro Sasaki , Tomonobu Hata Tomonobu Hata
Published: October 2002

Using a (ZrTi+PbO) composite target in the quasi-metallic mode reactive sputtering (QMMRS) system, perovskite Pb(Zr,Ti)O3 films were deposited at a rate of 8 nm/min at the substrate temperature of 450°C. X-ray diffraction analysis of a film deposited at a substrate temperature of 450°C and with O2/Ar = 2.1%, using a powder target with a stoichiometric composition of PZT of Pb:Ti:Zr =1:0.5:0.5, revealed that it had almost the same crystal structure as that of a film produced using a (ZrTi+30%PbO) composite target. The deposition rate was 3 nm/min. To fabricate PZT thin films at a high deposition rate using QMMRS, a (Pb+ZrO2+Ti) mixture target was prepared. Although it is possible to produce a film with a high deposition rate at 450°C, perovskite PZT film could not be obtained. This may be due to differences in sputtering yield for Zr and ZrO2 atoms or in the heat of formation of PbO and ZrO2 molecules. A new solid target that is free from the problems associated with the (Pb+ZrO2+Ti) mixture target is currently being developed.
Electroluminescent Properties of a Novel σ*–π* Conjugated Polymer, Poly[1,1-(2,3,4,5-tetraphenylsilole)]
Authors: Xu Yonghua , Fujino Takahiro , Naito Hiroyoshi , Dohmaru Takaaki , Oka Kunio , Sohn Honglae , West Robert
Published: October 2002

The optical and electronic properties of a
σ*–π* conjugated polymer,
poly[1,1-(2,3,4,5-tetraphenylsilole)] (PTPS), have been studied. PTPS
shows emissions of σ*–π and
π*–π transitions at 356 and 520 nm, respectively. PTPS light-emitting
diodes (LEDs) with a single layer structure emit green-yellow light, corresponding to
the π*–π transition, with an external quantum
efficiency of 3×10-2%. The effect of
the doping of poly(methylphenylsilane) (PMPS), a good hole transport material, into
PTPS has also been studied. The shapes of the photoluminescence spectra of
PMPS:PTPS films are the same as those of a PTPS film, indicating efficient energy
transfer from PMPS to PTPS. PTPS:PMPS LEDs emit essentially the same green-yellow light as PTPS LEDs and exhibit better device characteristics than those
without PMPS, that is, smaller turn-on voltages, larger current densities, and larger
external quantum efficiencies. The PMPS:PTPS (PMPS: 30 wt%) LEDs show a
luminance of 27 cd/m2 at a driving current density of 13 mA/cm2.
Highly Accurate Process Proximity Correction Based on Empirical Model for 0.18 µm Generation and Beyond
Authors: Kotani Toshiya , Tanaka Satoshi , Yamamoto Kazuko , Kobayashi Sachiko , Uno Taiga , Inoue Soichi
Published: October 2002

The main factors affecting correction accuracy of simulation-based process proximity
correction (simulation-based PPC) performed under actual process conditions are investigated
in order to obtain highly accurate correction values within allowable correction time. Four
important factors are considered for accurate simulation-based PPC. First, the approximation
to a one-dimensional (1D) proximity region perpendicular to the corrected edge is effective for
edges longer than 1.0–1.5 µm of corrected pattern since the optical proximity effects (OPEs)
induced by non-perpendicular direction of the edge are negligible. Second, the reliability of
measured data is improved due to removal of systematic errors by statistical methods. Third,
the empirical model based on multiple Gaussian functions is necessary for accurate prediction
of process proximity effects (PPEs) induced by mask fabrication, development and etching
processes. Finally, for obtaining accurate and fast corrections, it is important to optimize the
proximity region according to the degree of PPEs induced by long range
effects, like micro-loading effects.
Critical Dimension Controllability Evaluation Based on Process Error Distribution for 150 nm Devices
Authors: Fujimoto Masashi , Yamanaka Koji , Hashimoto Takeo , Kasama Kunihiko
Published: October 2002

In this study, the critical dimension (CD) controllability of 150 nm patterns was
evaluated by aerial image simulation. We considered three types of process errors (dose errors,
focus errors, and mask CD errors) and evaluated the CD error distribution by calculating both
the CD and the probability for each of the various combinations of process errors. The effects
of high numerical-aperture (NA) KrF exposure on CD controllability were investigated in
detail. In contact hole patterns and line patterns with various pitches, the CD controllability
was significantly improved by increasing the NA, up to about 0.72. However, NA of more
than 0.72 does not seem to have further significant effects on the CD controllability. We also
investigated the CD controllability in ArF exposure. ArF exposure is expected to exhibit
better CD controllability for contact hole patterns and line patterns with various pitches, even
under lower NA conditions than KrF exposure.
Fabrication Process and Interfacial Study of High-TcJosephson Junctions fabricated using the Focused Ion Beam Technique
Authors: Morohashi Shin'ichi , Wen Jianguo , Enomoto Youichi , Koshizuka Naoki
Published: October 2002

We describe the fabrication processes of high-TcJosephson junctions fabricated using the focused ion beam (FIB) technique, and the junction interfaces using cross-sectional transmission electron microscopy. This FIB technique has the two functions of etching and deposition. Using each of the FIB functions independently, and also together, we have fabricated junctions with three types of structures. The two types of junctions fabricated using each of the FIB functions independently are classified as grain boundary junctions with multi-grain boundaries, and the junction fabricated using both FIB functions is a proximity-effect type junction.
A Study of Loading Effect during Electron-Beam Exposure and Etching Process in Photomask Fabrication
Authors: Choi Ji-Hyeon , Kim Byung-Gook , Jeon Chan-Uk , Cho Sung-Yong , Choi Seong-Woon , Sohn Jung-Min
Published: October 2002

As the requirements of critical dimension (CD) uniformity on photomasks continue to tighten with
advanced logic and memory devices, the dry etching process should be adopted to meet the needs of the
optical proximity effect correction (OPC) and reduced bias process [W. T. Chen and M. Kamma: Proc. SPIE 3412 (1998) 149.]. There are severe CD variations in
the dry etching process due to chrome (Cr) pattern density with various clear and dark fields. Through
experiments, on the CD variation was investigated in the wet etching process, as well as in the dry etching
process. This work focused on the tracing-determining the actual cause of the loading effect. It was
revealed that what accounts for a major portion of the loading effect is not the Cr dry etching process, but
the rescattering of electrons of the electron-beam exposure system. Rescattered electrons in this article
refers to electrons that are reflected between the specimen and the lower parts of the electron-beam
column and expose the unexposed area. In this paper, the existence of rescattered electrons was
experimentally confirmed with a 10 kV acceleration-voltage system and the CD variation by reflected
electrons was also investigated.
Phantom Exposure of Chemically Amplified Resist in KrF Excimer Laser Lithography
Authors: Kawai Yoshio , Deguchi Kimiyoshi , Nakamura Jiro
Published: October 2002

The phantom exposure of a chemically amplified resist in KrF
excimer laser lithography can be attributed to acids generated in
the ambient air exposed to KrF excimer laser light. These acids
diffuse into the resist film and act as catalytic acids. Phantom
exposure expanded to more than 10 mm outside the exposure field,
and degrades the patterning characteristics. The critical dimension
(CD) uniformity can be improved by using an overcoat to protect the
resist from the acid.
Application of Zirconium Silicon Oxide Films to an Attenuated Phase-Shifting Mask in ArF Lithography
Authors: Matsuo Takahiro , Onodera Toshio , Nakazawa Keisuke , Ogawa Tohru , Morimoto Hiroaki , Haraguchi Takashi , Fukuhara Nobuhiko , Matsuo Tadashi , Otaki Masao , Takeuchi Susumu
Published: October 2002

We have investigated the durability under ArF excimer laser light of bi-layer zirconium
silicon oxide (ZrSi
x
O
y
) films used as the shifter of an attenuated phase-shifting mask (Att-PSM). We have achieved excellent stability by using the structure of the transparent film
(TF) on the absorptive film (AF) rather than the structure of AF on TF. We can estimate a
sufficient lifetime of more than three years in mass production for TF/AF/quartz structure.
By XPS analysis, it has been clarified that the surface of TF is stable to ArF irradiation and
the surface of AF is easily oxidized by the irradiation. TF/AF/quartz is the optimum
structure for the prevention of surface oxidation. 0.13 µm line patterns have been achieved
with a sufficient process margin by using optimized bi-layer ZrSi
x
O
y
films as an Att-PSM and
off-axis illumination in ArF lithography.
Development of a 2 kHz F2 Laser for 157 nm Lithography
Authors: Nagai Shinji , Takehisa Kiwamu , Enami Tatsuo , Nishisaka Toshihiro , Fujimoto Junichi , Wakabayashi Osamu , Mizoguchi Hakaru , Takahashi Akihiko
Published: October 2002

We have developed a 2 kHz repetition rate discharge-pumped molecular fluorine laser oscillating at
157 nm. It has achieved an average power of 22 W at the repetition rate of 2 kHz with a newly developed
solid-state pulse power module which has a maximum input energy of 6 J/pulse. The multi-kilohertz F2
laser is a key device for 157 nm lithography aimed at the design rule
of below 0.10 microns.
Aberration Tolerance for 130 nm Lithography from Viewpoint of Process Latitude
Authors: Saito Takashi , Watanabe Hisashi , Sasago Masaru
Published: October 2002

In this paper, aberration tolerance of a projection lens for 130 nm patterning using ArF
lithography is described. The influences of the three kinds of lens aberration were analyzed
with aerial image simulation. Four mask types were evaluated, each mask has a vertical and
horizontal isolated line as well as vertical and horizontal (V&H) dense lines. The common
process latitudes for four patterns were calculated, then the aberration tolerance was
evaluated for each mask type. From the viewpoint of the process latitudes, the aberration
tolerance was about 0.14λ in case of the Levenson-type mask for the vertical isolated line
only. When the common process latitude for V&H isolated and dense lines was considered,
the aberration tolerance decreased to 0.02λ in the case of spherical aberration. We also
found that the influence of aberrations differed depending on the mask type. Therefore, the
mask types should be selected considering their characteristics with respect to the
aberrations.
Thermal Characteristics of Scattering Stencil Reticle for Electron Beam Stepper
Authors: Morita Kenji , Hirayanagi Noriyuki , Suzuki Shouhei , Kawata Shintarou , Mizukami Hiroshi , Takahashi Satoshi , Miki Yuichiro
Published: October 2002

We are developing an electron beam (EB) stepper as one of the next-generation
lithography systems for feature sizes of less than 100 nm. As a reticle for the EB stepper
using a high-power EB (accelerating voltage:100 kV, current on reticle:100 µA), a scattering
stencil reticle with a grid-grillage structure is investigated. We evaluated the deformation
of a scattering stencil reticle, due to thermal expansion and bending by gravity. These
phenomena are computer simulated. Immediately after the EB is illuminated, the
temperature of the 2-µm-thick membrane of the reticle increases about 4 K. The induced
pattern distortion is about 2 nm and gravitational horizontal deformation is less than 1 nm.
Thermal and gravitational vertical deformations are about 3 nm and about 6 nm,
respectively. From these results, the induced image horizontal distortion is about 0.5 nm and
vertical distortion is about 0.4 nm on the wafer for a demagnification(1/4) system, due to
thermal expansion and bending by gravity. This shows that a scattering stencil reticle with a
2-µm-thick membrane is applicable to an EB stepper for high throughput and high
resolution, and has advantages compared with a conventional EB lithography mask from the
viewpoint of thermal problems.
Novel Alignment Method for Planarized Substrates in Electron Beam Lithography
Authors: Yamamoto Jiro , Moniwa Akemi , Murai Fumio , Terasawa Tsuneo
Published: October 2002

We have developed an alignment mark structure for planarized
substrates, that enables high alignment accuracy in electron beam
lithography. Not only heavy metals but also light elements are used
as marks. For multilevel metalization processes, we confirmed the
advantages of buried heavy-metal marks by detection-signal
simulation and exposure experiments. This mark structure allows the
detection of alignment marks using an electron beam, even when they
are covered by a SiO2 film up to a few micrometers thick or
with metal films that prevent detection by an optical method. Buried
light-element alignment marks, such as a SiO2 mark in a Si
substrate, are also effective. Such marks are suitable for use prior
to the gate-fabrication process, especially for the shallow groove
isolation (SGI) process, because they do not cause heavy-metal
contamination. Marks consisting of periodic narrow lines made with
light elements are particularly suitable for wafer planarization processes.
Low-Energy E-Beam Proximity Lithography (LEEPL): Is the Simplest the Best?
Authors: Utsumi Takao
Published: October 2002

Low-energy e-beam proximity lithography (LEEPL) is proposed as the simplest integrated circuit
lithography for minimum feature sizes ≤0.1 µm. This new e-beam lithography is similar to 1× X-ray
proximity lithography except that the X-ray beam is replaced with a beam of low-energy electrons of 2 kV.
This low e-beam energy permits the use of single-crystal 0.5-µm-thick silicon stencil masks without an
absorbing metal layer of high atomic number. This membrane mask is thick enough for good heat
conduction and thin enough for feature sizes ≤0.1 µm. Mask distortion caused by fabrication can be
corrected by a fine-tuning deflector. Therefore, a mask with a residual distortion of more than 100 nm is
acceptable. This eliminates the main difficulty of X-ray proximity lithography. The proposed system is
not affected by a space-charge effect in the electron optics column, and a proximity effect with respect to
both wafer and mask writings, and it is fundamentally low-power lithography which needs no special
cooling system. The analysis shows that the e-beam column can be made entirely of electrostatic
components to achieve sufficient resolution. For an appropriate resist process for this low-energy e-beam,
we propose a bilayer process such as the chemical amplification of resist lines (CARL) process which
consists of a chemically amplified thin deep ultraviolet (DUV) photoresist and a thick planarizing layer as a
starting point. We estimated a throughput of about 40 12 inch wafers per hour and a resolution of a
significantly less than 50 nm.
Alignment Mark Optimization to Reduce Tool- and Wafer-Induced Shift for XRA-1000
Authors: Ina Hideki , Sentoku Koichi , Matsumoto Takahiro , Sumitani Hiroaki , Suita Muneyoshi
Published: October 2002

As semiconductor device geometry shrinks down to the 100 nm order for the most critical layers,
requirements for overlay accuracy have become increasingly strict in the semiconductor manufacturing
process. One contribution to overlay error (particularly alignment error) originates from the process and
tool interaction. Therefore, it is necessary to improve the alignment accuracy of both the process and the
tool. Alignment errors can be separated into tool-induced shift (TIS), wafer-induced shift (WIS), and
TIS-WIS interaction. In this study, optimization of the alignment mark will be proposed in order to
reduce not only TIS, but also WIS for the XRA-1000, which is the volume production stepper of proximity X-ray lithography (PXL).
Characterization of 193 nm Chemically Amplified Resist during Post Exposure Bake and Post Exposure Delay
Authors: Lee Eun-Mi , Sung Moon-Gyu , Lee Young-Mi , Sohn Young-Soo , Oh Hye-Keun
Published: October 2002

We investigated the property change of a positive type 193 nm chemically amplified
resist (CAR) during post exposure bake (PEB) and post exposure delay
(PED). Upon PEB the thickness and optical property are changed.
These changes depend on the exposure energy and the PEB conditions.
The thickness and the imaginary refractive index changes during PEB are
determined. The thickness reduction and the refractive index changes are related to the de-protection of
the resist. By modeling these relationships the concentration of
de-protected site of the resist and the parameters are determined.
The PED effect is also considered and included in the model.
The de-protection parameters needed for the 193 nm lithography are
extracted. The obtained parameters are used with the lithography simulation for profile calculation,
and the results are compared with the observed SEM resist profile.
Photoacid Structure Effects on Environmental Stability of 193 nm Chemically Amplified Positive Resists
Authors: Yoshino Hiroshi , Itani Toshiro , Takimoto Michiya , Tanabe Hiroyoshi
Published: October 2002

The effects of a generated photoacid structure on environmental stability at post-exposure bake (PEB) and during post-exposure delay (PED) were investigated for a 193 nm
chemically amplified positive resist composed of an ethoxyethyl-blocked alicyclic copolymer
and an iodonium sulfonate photoacid generator (PAG). It was found that the influence of
airborne contaminants at PEB was less than that during PED. The relationship between
environmental stability and generated photoacid properties such as acid strength, reactivity to
amine, acid molecular size, reaction efficiency, and activation energy for the deblocking
reaction, are discussed. The environmental stability was greatly dominated by the acid
strength of generated photoacid, which contributed to the reactivity of the acid with base
contaminants. In addition, a good correlation was obtained between the acid molecular size
and the lithographic performance. Weak acid (pKa ∼-7) with moderate size (∼100 Å3)
exhibited both high environmental stability and high lithographic performance. The high
environmental stability of the resist with weak acid was almost the same as that of the 248 nm
acetal-type resist, and it is sufficient for practical use.
Design Concepts of Single-Layer Resists for Vacuum Ultraviolet Lithography
Authors: Kishimura Shinji , Katsuyama Akiko , Sasago Masaru , Shirai Masamitsu , Tsunooka Masahiro
Published: October 2002

We investigated the possible use of single-layer resists in vacuum ultraviolet (VUV) lithography. The transmittances in the VUV region of commonly used polymers for photoresists were almost the
same. These values were about 20% at 157 nm per 1000 Å-thickness at most. The transmittance
at 157 nm of a poly (p-hydroxystyrene) (PHS)-type polymer was slightly increased by halogenation of
the aromatic group. Negative working behavior was observed for PHS-type resists. It is thought that
both crosslinking and deprotection occurred in PHS-type polymers. A methacrylate-type resist
showed high contrast due to the photodecomposition of the base polymer and photo-deprotection in
addition to acidic deprotection. It was estimated that the resolution capability of this resist was 80 nm
lines and spaces (L/S) (λ157 nm, NA 0.65) using a PROLITH/3D lithography simulator with
experimental dissolution data.
Theoretical Calculation of Photoabsorption of Various Polymers in an Extreme Ultraviolet Region
Authors: Matsuzawa Nobuyuki N. , Oizumi Hiroaki , Mori Shigeyasu , Irie Shigeo , Shirayone Shigeru , Yano Ei , Okazaki Shinji , Ishitani Akihiko , Dixon David A.
Published: October 2002

We have calculated the linear absorption coefficients of various
resist polymers using the mass absorption coefficients at 13 nm and
the density obtained from the graph-theoretical treatment derived
by Bicerano. The values indicate that the transmittance at 13 nm of
conventional resists used in 193-nm, 248-nm and 365-nm
lithography is about 30% when the thickness is 3000 Å and 60–70%
when it is 1000 Å. This shows that conventional resists are suitable
for an EUVL (extreme ultraviolet lithography) thin-layer resist (TLR)
process using a hard-mask layer, but their large photoabsorption
makes them unsuitable for a single-layer resist (SLR) process. To
design polymers that are suitable for an SLR process, we further
calculated the absorption of about 150 polymers. The results
suggest that the introduction of aromatic groups into a polymer not
only reduces the absorption at 13 nm but also increases the etching
resistance.
Study on the Properties of Interlayer Low Dielectric Polyimide during Cl-Based Plasma Etching of Aluminum
Authors: Kim Sang Hoon , Moon Ho Sung , Woo Sang Gyun , Ahn Jinho
Published: October 2002

The properties of polyimide for interlayer dielectric applications are investigated during plasma etching
of aluminum on it. Chlorine-based plasma generally used for aluminum etching results in an increase in the
dielectric constant of polyimide, while SF6 plasma exhibits a high polyimide etch rate and a reducing effect
of the dielectric constant. The leakage current of polyimide is significantly suppressed after plasma exposure.
An optimal combination of Al etch with Cl2 plasma and polyimide etch with SF6 plasma is expected to be a
good tool for realizing multilevel metallization structures.
High-Speed Maskless Laser Patterning of Thin Films for Giant Microelectronics
Authors: Yavas Oguz , Takai Mikio
Published: October 2002

Maskless patterning of indium tin oxide (ITO) thin films was studied using a diode
pumped Q-switched Nd:YLF laser. The wavelength was systematically varied from infrared
to ultraviolet to investigate the effect of different conditions for light absorption by the ITO
film and the glass substrate. Electrically isolating lines could be etched at all wavelengths
used. However, residue-free removal of the ITO film could be achieved only when the glass
substrate was strongly absorbing the incoming laser light. In all other cases, i.e., strong light
absorption by the film only, weak absorption by the film and transmission by the substrate,
or strong absorption by the film but weak absorption by the substrate, a
ripple-like morphology in the etched groove was produced due to incomplete material removal.
In case of ITO films on fused quartz substrates, therefore, the ripple-like morphology in
the etched groove was observed at all wavelengths used. The results are consistent with
thermal vaporization as the mechanism for the material removal which was confirmed by the
predictions of numerical computations for the laser-induced temperature rise.
Conditions for Fabrication of Highly Conductive Wires by Electron-Beam-Induced Deposition
Authors: Hiroshima Hiroshi , Suzuki Norihito , Ogawa Naomi , Komuro Masanori
Published: October 2002

Conductive wires were fabricated by electron-beam-induced deposition
(EBID) using WF6 gas. It was difficult to fabricate highly conductive wires with good
reproducibility unless samples were cleaned before EBID. Contamination appears
to reduce the conductivity of the wires. O2 plasma cleaning of samples before EBID
seems to reduce contamination growth; however, it is not effective for regions in the
vicinity of Au patterns. We found that by combining annealing at 300°C and O2
plasma cleaning, highly conductive wires could be fabricated with relatively good
reproducibility in such regions. A linear relation was found between wire
conductance and linedose at lindoses of more than 70 µC/cm. The change in
deposition yield estimated from the conductance was about 12% when the gas flux
was halved. Wires with a length of less than 40 nm were less conductive than longer
wires because of a shortage in gas supply.
Electron Beam Doping (Superdiffusion) in Damage-Free Regions of Semiconductors by the Kick-Out Mechanism (Secondary-Ion Mass Spectrometer and Photoluminescence Measurements)
Authors: Wada Takao , Fujimoto Hiroshi
Published: October 2002

Zn atoms were doped into the damage-free regions of GaAs by a 750 keV electron
beam doping method at room temperature. The experimental structures were GaAs (layer 3)/Zn//Zn/GaAs (layer 1), whose Zn/GaAs consists of Zn evaporated layers on
GaAs wafers. The Zn overlayer surface is only in contact with another Zn substrate
surface. The surfaces of layer 3 (GaAs) were irradiated with a
fluence of ∼5×1017 electrons cm-2 at 100°C in N2 gas. The 750 keV electrons do not penetrate the Zn layers,
because of larger thickness for the ranges of electrons. The diffusion profiles of Zn into
GaAs were measured with a secondary-ion mass spectrometer. Photoluminescence
spectra for electron beam Zn-doped GaAs were investigated.