bluuebunny/crossref_metadata_2025 huggingface dataset:
Kikuchi-Band Analysis of X-Ray Photoelectron Diffraction Fine Structure of Si(100) by Precise Angle-Resolved X-Ray Photoelectron Spectroscopy
Authors: Katayama Toshiharu , Yamamoto Hidekazu , Mashiko Yoji , Koyama Hiroshi , Kawazu Satoru , Umeno Masataka
Published: October 2002

X-ray photoelectron diffraction fine structure of Si(100) is studied
with precise angle-resolved X-ray photoelectron spectroscopy. Polar-angle intensity distributions of the Si 2p photoelectron emission excited
by Al Kα X-rays are measured from H-terminated Si(100) along some
azimuthal angles, and are qualitatively interpreted using both forward-focusing peaks along zone axes and Kikuchi bands associated with planes
of low indices ({220}, {400}, {111} and {311}). To confirm the
interpretation experimentally, we prepare ultrathin Si(100) layers on SiO2
from silicon-on-insulator (SOI) wafers. The thicknesses of the ultrathin
Si(100) layers are adjusted so that the SOI layer is thick enough to exhibit
the forward-focusing peak along [100] but slightly thinner than the
thickness in which the contribution of the Kikuchi pattern weakens. It is
observed experimentally, for the first time, that the intensities of X-ray
photoelectron diffraction fine structure due to Kikuchi lines decreases for
such ultrathin Si(100), while the forward-focusing peak remains
unchanged, as expected from our interpretation.
Behavior of the Ion Sheath Instability in a Negative Ion Plasma
Authors: Kazunori Koga Kazunori Koga , Yoshinobu Kawai Yoshinobu Kawai
Published: October 2002

The ion sheath instability with half the ion plasma
frequency was observed around the separation grid
in a double plasma containing negative ions,
where the dominant negative ion species was specified from
the dispersion relation of the ion acoustic wave.
Detailed behavior of ion sheath instability was
examined as a function of concentration of negative ions
and bias potential of the separation grid.
By measuring the sheath structure formed around
the separation grid, it was found that
when the negative ion density was increased,
the ion sheath instability was suppressed.
Furthermore, the peak frequency decreased
with an increasing concentration of negative ions.
A Gated, Four-frame Pinhole Camera with Quantitative Image Acquisition
Authors: Bing Shan Bing Shan , Takeshi Yanagidaira Takeshi Yanagidaira , Katsuji Shimoda Katsuji Shimoda
Published: October 2002

A gated, multiframe microchannel plate soft X-ray sensor with quantitative acquisition has been developed. The system is composed of an image acquisition system and a gated pinhole camera capable of taking four successive frames at a time resolution of ∼220 ps. The response of the system has been quantitatively investigated. To perform a quantitative evaluation of the captured X-ray images, the image acquisition and measurement of the phosphor current are executed simultaneously in the experiment. The system has been examined using a plasma X-ray source generated by a plasma focus device with an additional gas puff. The compression and bifurcation process of plasma hot spots in a neon puffed experiment has been successfully recorded. Quantitative analysis of the images indicates that an order of 1016photons/(s·mm2·mrad2) emissions originate from the plasma in a soft X-ray region 6–14 Å.
Reshaping of Single-Crystal Silicon Microstructures
Authors: Yang Eui-Hyeok , Fujita Hiroyuki
Published: October 2002

This paper deals with the reshaping technology for realizing three-dimensional (3-D)
microstructures through plastic deformation of single-crystal silicon (SCS) films by applying
Joule heating. SCS beams are used for determining the behavior of SCS microstructures
during reshaping. The reshaped SCS structure has a sharp corner at a point where stress and
heat are concentrated. The plastic deformation caused by flow stress results in permanent 3-D shapes.
Atomic-Scale Electron Beam Processing
Authors: Kizuka Tokushi , Yanaka Takashi
Published: October 2002

Atomic-scale electron beam processing was demonstrated using high-resolution
transmission electron microscopy. Nanometer-size holes were produced through mag
nesium
oxide films. The minimum hole size was 0.84 nm and the minimum distance between
the
holes was 0.63 nm.
Dependence of Optical Constants on Film Thickness of Phase-Change Media
Authors: Miao X. S. , Chong T. C. , Huang Y. M. , Lim K. G. , Tan P. K. , Shi L. P.
Published: October 2002

The optical constants of phase-change films are assumed to be constant regardless of film thickness in conventional optical design and thermal simulation of multilayer structure optical disks. However this assumption is not valid when the phase-change film thickness in the optical disks becomes very small. In this study, the dependence of the optical constants on the thickness of Ge1Sb2Te4 phase-change films is investigated. The changes of the extinction coefficient k and the refractive index n (especially k) become significant when film thickness is in the range of 10 nm–30 nm, and become larger at shorter wavelengths such as the blue region. This dependence of optical constants (n and k) on the film thickness can be explained and confirmed based on the discontinuous film model of very thin film. These results are significant in improving the accuracy of optical design and thermal simulation of phase-change optical disks, as well as in the study of phase-change optical disks at shorter wavelengths.
Study of the Partial Crystallization Properties of Phase-Change Optical Recording Disks
Authors: Shi L. P. , Chong T. C. , Tan P. K. , Miao X. S. , Huang Y. M. , Zhao R.
Published: October 2002

The partial crystallization properties of Ge1Sb2Te4 phase-change optical disks are studied using two methods. The first one involves annealing of the samples in a vacuum oven while controlling annealing time and temperature, while the second one involves the use of a static tester. A difference in reflectivity was observed, indicating that different crystallization fractions give rise to different reflection levels. The optical constants of amorphous, partial and full crystaline states were measured by spectroscopic ellipsometry. The optical constant of the partial crystalline state was calculated under the assumption that the partial crystalline state is a combination of full crystalline and amorphous states. The crystallization fraction was determined by simulating the refractive index of the partial crystalline state. The stability of the partially crystalized disk was measured for more than 200 days demonstrating that the partially crystallied disk is very stable. A possible recording strategy using the multilevel reflection to realize multi-level reflection modulation recording in write-once media is discussed.
Reduction of Spontaneous Surface Segregation in (InP)2/(GaP)2 Quantum Wells Grown on Tilted Substrates
Authors: Cheng Yi-Cheng , Tai Kuochou , Chou Shu-Tsun , Huang Kai-Feng , Lin Wen-Jen , Lin Alpha C. H.
Published: October 2002

We have studied the growth mechanism of (InP)2/(GaP)2 short-period superlattices (SPS) and In0.5Ga0.5P quantum wells grown on tilted substrates using solid-source molecular beam epitaxy (SSMBE). Both the (InP)2/(GaP)2 SPS and In0.5Ga0.5P quantum wells show blue shifts of photoluminescence (PL) wavelengths when the substrate's tilting angle is increased. The blue shift is more prominent in the SPS structure than in the In0.5Ga0.5P quantum wells. By comparing PL, polarized PL spectra and transmission electron micrographs, we confirm that the ordering effect exists in both the (InP)2/(GaP)2 SPS and In0.5Ga0.5P quantum wells when the substrate tilt angle is small, and can be greatly reduced when the substrate tilt angle is increased. We believed that the height and density of steps on substrates with larger tilt angles repress the segregation of group III adatoms.
New Equalizer to Improve Signal-to-Noise Ratio
Authors: Miyanabe Shogo , Kuribayashi Hiroki , KaoruYamamoto KaoruYamamoto
Published: October 2002

Signal-to-noise ratio (SNR) of an optical memory disc deteriorates as the recording density
increases. The authors have coped with this problem and developed a new equalizer which can
improve the SNR by boosting higher frequency components on the readout signal without
increasing the inter-symbol interference (ISI). The authors measured the jitter values on a
prototype disc applying the new equalizer. The disc had a capacity of 15 Gbytes, a track pitch of
0.37 µm and a minimum pit length of 0.25 µm. An optical head with a second harmonic
generation (SHG) blue laser with a wavelength of 430 nm and an objective lens with a NA of 0.6
was used. As a result, it was confirmed that the new equalizer could improve not only the SNR
but also the tilt margins. Furthermore, the correlation between the jitter and the bit error rate
observed on a conventional equalizer was found unchanged even with the
new equalizer.
Signal Processing Algorithms for Doppler Effect Based Nanometer Positioning Systems
Authors: Wu Wen-Jong , Lee Chih-Kung , Hsieh Chi-Tang
Published: October 2002

Interferometers based on laser Doppler effect are used as the vehicle to examine the
cross relationship and performance impact among sub-systems such as optical layout,
mechanical layout, signal processing algorithm, and signal processing circuitry. The
classification of interferometers into the three main categories (e.g. homodyne, heterodyne and
quadrature) and their influence on signal processing algorithms and circuitry which impact
interferometer performance is examined. A quadrature configuration, found to have some
unique advantages, is detailed. Also presented is an experimental laser encoder set-up equipped
with a real-time signal processing circuitry based on a high performance field programmable gate
array (FPGA) circuitry with a PC interface for quadrature signal decoding that was constructed
to verify the quadrature configuration presented. The experimental data obtained that verifies
how this new system architecture can fulfill the stringent demands of today's high performance,
high accuracy metrology systems is also examined.
Analysis of the Crosstalk in a High-Density Optical Disc System
Authors: Yanagisawa Takuma , Nomoto Takayuki , Kuribayashi Hiroki , Ohsawa Seiichi
Published: October 2002

A crosstalk canceler has been proposed in order to readout a signal from a
high-density optical disc. We have confirmed by the computer simulations that a
crosstalk canceler is highly useful technology. Furthermore, we have calculated
the readout margins of the high-density optical disk system applying a blue laser,
a crosstalk canceler and some other signal processing methods.
The Nature of the Coupling Field in Optical Data Storage Using Solid Immersion Lenses
Authors: Milster Tom D. , Jo Joshua S. , Hirota Kusato , Shimura Kei , Zhang Yan
Published: October 2002

The field incident onto the interface between the solid immersion lens (SIL) and recording medium
is decomposed into two parts that exhibit different behavior as the beam propagates through the
recording layers. The homogeneous part is shown to diffract, and the inhomogeneous part decays
exponentially away from the bottom of the SIL. Reflection and signal contrast are calculated for a
phase-change recording medium. The dependences of the signal contrast on the gap width, the
refractive index of gap and the SIL are analyzed.
Deep UV Mastering Using an All-Solid-State 266 nm Laser for an over 20 GBytes/Layer Capacity Disk
Authors: Takeda Minoru , Furuki Motohiro , Yamatsu Hisayuki , Kashiwagi Toshiyuki , Aki Yuichi , Suzuki Akitoshi , Kondo Kenji , Oka Michio , Kubota Shigeo
Published: October 2002

The deep UV mastering process of the next generation high density disk is demonstrated for the first time using an all-solid-state
continuous-wave 266 nm laser. We have developed a novel deep UV master recorder with a laser source, and achieved a density of
20 Gbytes capacity (14 Gbit/inch2) with acceptable jitter for the compact disk size.
Observation of Extremely Low Defect Densities in Silicon Wafers
Authors: Schmolke Rüdiger , Gräf Dieter , Kirchner Ralf , Schauer Reinhard , Werner Norbert , Mayer Erwin-Peter , Wagner Peter
Published: October 2002

Defects in p-polished silicon wafers originating from Czochralski (Cz)-pulled crystals are commonly delineated by hot SC1 treatment with immersion times in the range from about 20 min to 4 h corresponding to silicon removals of 20 nm to 200 nm. This procedure is no longer applicable for wafers with defect densities that are orders of magnitude lower than in Cz p-wafers due to their very low count rates. However, a low defect density, such as in homoepitaxial silicon layers, can be investigated by sequentially treating wafers in hot SC1 solution several times so that the overall duration of the preparation is on the order of twenty hours resulting in a silicon removal of about 1 µm. Defects delineated by hot SC1 etching can, in addition, be investigated with an atomic force microscope. In the case of homoepitaxial silicon layers, these defects are identified as single as well as dual pits with a morphology characteristic of so-called crystal originated particles (COPs) as observed on p-Cz wafers. These COPs are related to voids generated by vacancy agglomeration in the growing ingot. The morphology of the delineated defects indicates that such voids exist in homoepitaxial layers as well, which is supported by the fact that the temperature range relevant for void formation in p-Cz silicon crystals is also used in silicon homoepitaxial growth. The oxygen backpressure during homoepitaxial silicon growth is negligible. Thus, formation of voids in the epitaxial layer is not influenced by oxygen, specifically when an oxygen-free silicon substrate, such as a wafer cut from a floating-zone (FZ) crystal, is used. However, not only single but also dual-pit COPs are observed on such epitaxial layers after delineation, which questions assumptions and models in the literature attributing the formation of multiple voids in p-Cz silicon crystals to the role of oxygen.
Influence of Unbalanced Magnetron and Penning Ionization for RF Reactive Magnetron Sputtering
Authors: Miyazaki Hidetoshi , Kamei Masayuki , Shigesato Yuzo , Yasui Itaru
Published: October 2002

Thermochromic VO2 films were deposited by reactive rf magnetron sputtering using balanced and
unbalanced magnetrons, and during deposition, helium was mixed into the carrier gas in order
to activate a reactive gas (oxygen). It was clarified through V
sdc measurements that the plasma
parameter was changed by varying the magnet configuration. The electron temperature and
Penning ionization increased upon mixing helium into the carrier gas. These effects enabled VO2 films
to be deposited under a wide range of sputtering conditions.
Vacancy Distribution in Aluminum Interconnections on Semiconductor Devices
Authors: Minoru Aoyagi Minoru Aoyagi , Kunihiro Asada Kunihiro Asada
Published: October 2002

The vacancy distribution in Al–2 wt%Si interconnections covered with a SiN passivation layer on
semiconductor devices was studied by means of a numerical calculation. The vacancy distribution was
calculated with the stress-induced vacancy model which shows the relation between the hydrostatic stress
and the vacancy concentration. Calculated results showed that the stress and vacancies are concentrated
near the sidewalls in interconnections, and that their gradients are directed toward the corners and
sidewalls in interconnections. If vacancy sinks exist at the corners or sidewalls, vacancies would migrate
easily in these directions due to the gradient force attributable to the vacancy distribution. The calculated
results agree with experimental results in terms of the dependence of void formation on interconnection
width and thickness.
Continuous Output Beam Steering in Vertical-Cavity Surface-Emitting Lasers with Two p-Type Electrodes by Controlling Injection Current Profile
Authors: Ide Toshihide , Shimizu Mitsuaki , Mukai Seiji , Ogura Mutsuo , Kikuchi Takuya , Suzuki Yoshihiro , Kaji Ryosaku , Itoh Hideo , Watanabe Masanobu , Yajima Hiroyoshi , Nemoto Toshio
Published: October 2002

Using vertical-cavity surface-emitting lasers with two p-type electrodes,
continuous output beam steering was achieved for the first time by
controlling the injection current profile. The far-field peak position can
be shifted linearly by varying the ratio between injection currents into the
two p-type electrodes. The deflection angle measured from the surface
normal direction ranges from -1.3° to +1.0°. Also, we investigated
operating characteristics that are important for optical processing such as
optical fuzzy inference.
Dichromated Gelatine as a Material of Optical Element
Authors: Lee Lee , Hyuk-Soo Hyuk-Soo , Cho Cho , Dong-Hyun Dong-Hyun , Choi Choi , Yong-Jin Yong-Jin , Son Son , Jung-Young Jung-Young , Park Park , Seung-Han Seung-Han
Published: October 2002

In the fabrication process of optical elements (OEs) by the laser scanning method using a dichromated
gelatin (DCG) photoplate, the expansion and drying stress of gelatine caused by inhomogeneous liquid
flow inside the gelatine affects the shape of OEs. The reason this inhomogeneous liquid flow exists in
the energy oversaturated parts of OEs is the presence of surplus energy. In order to obtain the OEs of
desired spherical lens shape, the drying stress should be reduced and therefore the maximum energy of
the illuminating laser should be defined not to cause the surplus energy. The maximum energy is
investigated according to the relative concentrations of (NH4)2Cr2O7 to DCG. The use of photoplates with a relative concentration of (NH4)2Cr2O7 to gelatin of more than 20% has some advantages when making the lens raster, especially a short-focal-length lens raster. It is also very important to increase the drying time to reduce the total drying stress by maintaining high humidity during the drying process.
Mn(Thin-Film)/Si(Substrate) Contacts: Analysis of the Buried Interface by Soft X-Ray Emission Spectroscopy
Authors: Wang Jinliang , Hirai Masaaki , Iwami MasahikoKusaka , Morii Takashi , Watabe Hirokuni
Published: October 2002

Electron-probe soft X-ray emission spectroscopy (SXES) has been
applied to the nondestructive analysis of the buried interface of a
Mn(thin-film)/Si(substrate) contact system, where the energy of the
primary electrons, E
p, is varied below 20 keV. An important point of this
analysis is that SXES gives a specific signal for each chemical element in
different chemical bonding states. The Mn(thin-film)/Si(100) specimen
not subjected to heat treatment did not show any additional phase except
for Mn and Si at the interface region within the detection limit of the
present experiment. The specimen subjected to heat treatment at
350°C for 3 min showed a layered structure of Mn/MnSi/MnSi1.7/Si(100) from
the top to the substrate.
Comparison of Radiation Diffraction Effects in a Sheet-beam and a Cylindrical-beam Free-electron Laser
Authors: Choi Eungki , Seo Yoonho
Published: October 2002

The growth characteristics of the radiation field are compared in
high-gain Compton free-electron lasers utilizing a sheet beam and
a cylindrical beam. It is observed that the sheet beam has a better
mode-confining property for the same diffraction parameter.
This beneficial effect of the sheet beam geometry, however,
seems to result in a higher growth rate than the cylindrical beam
only for sufficiently large diffraction parameters.
Photoluminescence Properties of Ce1-xTbxMgAl11O19 Phosphor Particles Prepared by Spray Pyrolysis
Authors: Kang Yun Chan , BinPark Seung , Lenggoro I. Wuled , KikuoOkuyama KikuoOkuyama
Published: October 2002

Spray pyrolysis method was applied to the preparation of
submicron Ce1-x
Tb
x
MgAl11O19 phosphor particles.
The characteristics such as photoluminescence, crystallinity, and
morphology were investigated under various preparation
conditions. While the as-prepared particles by spray pyrolysis at
temperature of 900°C had amorphous phase, the particles
calcined above 1400°C had phase-pure magnetoplumbite
structure, and its crystallinity increased with increasing the
calcining temperature. The as-prepared particles had spherical
morphology, submicron size, and narrow size distribution. The mean
size of the particles increased from 0.5 to 1.4 µm when the spray
solution concentration increased from 0.03 to 1.5 M. After
calcination, the particles showed 545 nm green emission
characteristic of Tb3+ ions with optimum excitation at
280 nm. The maximum luminous intensity was obtained at x=0.4. The
optimum calcining temperature for good brightness was
1500°C. Particles directly prepared by spray pyrolysis at
1500°C show good green emission characteristics and maintain
its sphericity and non-aggregation characteristics.
Preparation of PtO and α-PtO2 Thin Films by Reactive Sputtering and Their Electrical Properties
Authors: Yoshio Abe Yoshio Abe , Midori Kawamura Midori Kawamura , Katsutaka Sasaki Katsutaka Sasaki
Published: October 2002

Pt oxide thin films are
prepared by sputtering Pt target in an atmosphere containing
Ar and O2 gases.
Polycrystalline PtO and α-PtO2 films are obtained in O2
flow ratio regions of 30–50% and 80–100%, respectively, at a substrate
temperature of 300°C.
Electrical resistivity of the PtO film is found to be 1–2 mΩcm and
shows almost no temperature dependence.
The metallic character of the PtO film is assumed to be
suppressed by its poor crystallinity.
The α-PtO2 film has a
large resistivity of approximately 1 Ωcm with a negative
temperature coefficient, which indicates semiconducting characteristics.
Thermal stability of PtO and α-PtO2 films in air and in vacuum
is studied. These films are
stable up to 500°C and 250°C in air and in vacuum,
respectively,
and are reduced to Pt above these temperatures.
Laser Cooling of Single174Yb+Ions Stored in a RF Trap
Authors: Sugiyama Kazuhiko
Published: October 2002

We demonstrate laser cooling of single174Yb+ions stored in a rf trap. Single174Yb+ions were loaded using a natural isotope mixture as source. To locate a single ion at the center of the trap, and consequently, to minimize the micromotion caused by the rf driving field, we introduced two compensation electrodes and applied dc voltages to them and to one of the endcap electrodes. We estimated the temperature of a trapped single174Yb+ion to be 150 mK from the residual Doppler width of the spectra observed by a frequency sweep of the cooling laser. In the estimation, the saturation broadening in the spectra was substituted by measurement of the power dependence of the spectral width. To count the number of trapped174Yb+ions, we detected sudden drops in the fluorescence intensity (quantum jumps) of individual ions caused by pumping to and deexcitation of the2F7/2state. We found that deexcitation of the2F7/2state is possible by driving the2F7/2–1D[3/2]3/2transition at 760 nm and the2F7/2–3D[9/2]7/2transition at 828 nm, in addition to the former methods of driving the2F7/2–1D[5/2]5/2transition at 639 nm and the2F7/2–2D5/2transition at 3.43 µm.
Electron Spectroscopy Using a Gas-Flow Proportional Counter under Gaseous Environment and its Application to X-Ray absorption fine structure Measurements
Authors: Hayakawa Shinjiro , Ishii Ichiro , Noda Junzo , Gohshi Yohichi
Published: October 2002

A gas flow proportional counter was utilized for electron
spectroscopy under a gaseous environment. The kinetic energy of the
electron can be measured as the number of conversion electrons created
from a single primary electron. The energy distributions of the
emitted electrons were measured from a Ni foil placed inside the
electron counter with monochromatized Cu Kα and Kβ X-ray
excitation. The resultant spectra show clear evidence of a Ni K shell
threshold due to the presence of Ni KLL Auger electrons. The energy
resolution (full width at half maximum) of the electron counter was
about 2.5 keV for 8 keV X-rays and electrons. The electron counter
was utilized for x-ray absorption fine structure (XAFS) measurements,
and an XAFS spectrum of sufficiently high quality for further analysis
was obtained using a conventional X-ray source. The advantage of the
electron counter is its high sensitivity and high signal-to-background
ratio especially when electrons with special kinetic energy are
collected.
Dual-Workfunction Gate Engineering in a Corner Parasitics-Free Shallow-Trench-Isolation Complementary-Metal-Oxide-Semiconductor Technology
Authors: Schwalke Udo , Füldner Marc , Bothe WalterZatsch , Janssen DariuschHadawi , Schon Peter
Published: October 2002

In this work, through-the-gate implantation (TGI) of channel- and well-doping is favorably
combined with n+/p+ gate implantation. This approach offers an additional degree of freedom
to optimize dual-workfunction gates independently from the fabrication of ultra-shallow
source/drain junctions. By using the same masks for each device type, no increase in process
complexity occurs. In combination with the extended trench isolation
gate technology (EXTIGATE) process architecture, a corner
parasitics-free shallow trench isolation (STI) is provided together with the separation of pre-implanted n+/p+ polySi areas to inhibit lateral n+/p+ cross-diffusion during gate activation.
Nitrogen co-implantation into the gate is implemented to suppress boron penetration and to
provide relief from residual impurity cross-diffusion within the gate during S/D anneals.
Besides high drive currents, excellent short channel-behavior and improved narrow width
characteristics are obtained with TGI-CMOS.
Improved Ti Self-Aligned Silicide Technology Using High Dose Ge Pre-Amorphization for 0.10 µm CMOS and Beyond
Authors: Ohuchi Kazuya , Miyashita Katsura , Murakoshi Atsushi , Yoshimura Hisao , Suguro Kyoichi , Toyoshima Yoshiaki
Published: October 2002

Improved Ti self-aligned silicide (SALICIDE) technology for 0.1 µm complimentary metal-oxide-semiconductor (CMOS) using high dose pre-amorphization implantation (PAI) is
developed. High dose PAI with As and Ge promotes the growth rate of silicidation on
polycrystalline silicon gate even when its length is reduced to 0.1 µm. Thus it achieves low
sheet resistivity at narrow lines. In addition, the advantage of Ge over As as PAI species is
confirmed. Ge PAI does not affect the parasitic resistance increase of p channel metal-oxide-semiconductor field effect transistor (pMOSFET) or junction leakage characteristics because
of its electrical neutrality and high solubility in silicon.
Improvement of Ultra-Thin 3.3 nm Thick Oxide for Co-Salicide Process Using NF3 Annealed Poly-Gate
Authors: Chang Tzu Yun , Lei Tan Fu , ShengChao Tien , Huang Cheng Tung , Chen Shi Kuan , Tuan Andy , SteveChou SteveChou
Published: October 2002

To get high quality ultra-thin oxide is very important and
difficult for IC industry now. Using NF3 annealed poly-Si gate to
improve gate oxide integrity is described. However, reducing gate,
source and drain parasitic resistance with gate lengths down to 0.2 µm is another key point. Co-salicide process can successfully reduce
the gate resistance even for a gate length of 0.075 µm. Although,
Co-salicide process has a leakage problem. Using NF3 annealing to
prevent Co diffusing into gate oxide is described too. Results show
that the optimal NF3 annealing significantly improves electrical
characteristics of ultra-thin oxide and Co-salicide process in terms
of leakage current and breakdown field, as compared to the samples
without NF3 annealing.
Preparation of Bi4Ti3O12 Thin Films by MOCVD Method and Electrical Properties of Metal/Ferroelectric/Insulator/Semiconductor Structure
Authors: Kijima Takeshi , Matsunaga Hironori
Published: October 2002

Pt/Bi4Ti3O12(001)/Bi2SiO5(100)/Si(100) structures have been fabricated by
the metalorganic chemical vapor deposition (MOCVD) at 500°. Bi2SiO5 film is used
as a buffer layer to grow ferroelectric Bi4Ti3O12 films because of its relatively high
dielectric constant (ε=30). The memory window has a C-V characteristic of about 0.8 V, and the retention time estimated by the zero-bias capacitance for the
Pt/100-nm-Bi4Ti3O12/30-nm-Bi2SiO5/Si/Al structure is more than 11 days.
Lateral Diffusion Distance Measurement of 40–80 nm Junctions by Etching/TEM-Electron Energy Loss Spectroscopy Method
Authors: Kunimune Yorinobu , Nishio Naoharu , Kikuchi NoriyukiKodama , Toda Takeshi , Mineji Akira , Shishiguchi Seiichi , Saito Shuichi
Published: October 2002

A new technique to measure the lateral diffusion distance of
boron has been developed by wet-etching combined with TEM and
Electron Energy Loss Spectroscopy (TEM-EELS). The position at a
dopant concentration of 5×1018 cm-3 can be
correctly delineated with a spatial resolution of less than 5
nm. This technique is based on the fact that the gradient of the
etched surface changes discontinuously at a dopant concentration of
5×1018 cm-3. This characteristic appeared for all carrier profiles as long as the etching time was sufficiently long. Etching time optimization is needed because an incubation time exists before the etching starts and because the incubation time depends on carrier distribution. Thickness distribution after the etching is measured by TEM-EELS which enables a high spatial resolution measurement. The lateral diffusion distance at the pn junction measured by this technique was about 0.6 times of the vertical diffusion distance for 40–80 nm junctions. These results were compared with those obtained by an electrical C-V measurement, and were consistent.
Studies of Boron Segregation to {311} Defects in Silicon-Implanted Silicon
Authors: Jianxin Xia Jianxin Xia , Tomoya Saito Tomoya Saito , Ryangsu Kim Ryangsu Kim , Takenori Aoki Takenori Aoki , Yoshinari Kamakura Yoshinari Kamakura , Kenji Taniguchi Kenji Taniguchi
Published: October 2002

Czochralski Si wafers with a boron concentration of 2.7×1017 cm-3 were implanted with 50 keV or 150 keV Si+ with doses from 5×1012 cm-2 to 5×1015 cm-2, followed by annealing at 670°C, 720°C or 820°C in nitrogen ambient. During thermal annealing, boron pile-up in the {311} defect region was observed for the first time. In higher temperature annealing, the boron pile-up forms and dissolves more quickly, but has a lower peak value. The boron pile-up forms in the region where the self-interstitial concentration exceeds 3×1017 cm-3 regardless of implant energy and dose. The boron pile-up originates from the boron segregation to {311} defects. The process of boron segregation is limited by boron diffusion. The number of boron atoms segregated to {311} defects increases with annealing time, as t
1/2. After reaching its maximum, the number of segregated boron atoms falls exponentially with a characteristic decay time of 14 h at 670°C or 3 h at 720°C. Spreading resistance profiling reveals that boron atoms segregated to {311} defects are electrically inactive.
Deuterium Effect on Stress-Induced Leakage Current
Authors: Lin Bo Chun , Cheng Yih Chung , Chin Albert , Wang Tahui , Tsai Chun
Published: October 2002

We have studied and compared stress-induced leakage current in oxides
subjected to H2 and D2 annealing. There is not much difference in stress-induced
leakage current between thick 70-Å-oxides annealed by these two isotopes. In sharp
contrast, an improvement of several-fold in stress-induced leakage current is observed
in 27-Å-thick oxides annealed in D2 ambient compared to that annealed in H2. The
significant improvement in this direct-tunneling oxide may be due to the passivation
of intrinsic defects and dangling bonds in a transition SiO
x
layer.
Low-Contact Resistance Poly-Metal Gate Electrode Using TiN/Thin TiSi2/Poly-Si Structure
Authors: Ohtake Fumio , Nara Yasuo
Published: October 2002

A low-contact resistance poly-metal gate system consisting of TiN/thin TiSi2/poly-Si is
described. A poly-metal gate is one of the candidates for the next generation of metal-oxide-semiconductor field effect transistor (MOSFET) gate structures. The characteristics between the
barrier metal and the poly-Si are important in achieving a high-performance poly-metal gate
structure. In this study, the inserting of a thin TiSi2 layer between the TiN and the poly-Si
produced a low-contact resistance between the TiN and the poly-Si, which was an acceptable
improvement. The thinner the inserted TiSi2, the lower the contact resistance. In n- and p-channel MOSFETs with a TiN/TiSi2 (5 nm)/poly-Si gate structure having a gate oxide thickness
of 4 nm, the lateral diffusion of the gate dopant was suppressed. This occurred because the
inserted TiSi2 was thin enough to prevent the gate dopants from moving through the TiSi2.
Highly Uniform Low-Pressure Chemical Vapor Deposition (LP-CVD) of Si3N4 Film on Tungsten for Advanced Low-Resistivity “Polymetal” Gate Interconnects
Authors: Akasaka Yasushi , Miyano Kiyotaka , Takahashi KazuakiNakajima , Tanaka Satoko , Suguro Kyoichi
Published: October 2002

A W/WSiN/poly-Si multilayered “polymetal” gate structure has been proposed. An extremely low sheet resistivity can be achieved with this structure (1.4 Ω/□:T
W=100 nm). Moreover, a polymetal gate with Si3N4 cap and sidewalls (Si3N4-capped polymetal) enables the self-aligned contact technique and source/drain self-aligned silicide (SALICIDE). Thus, an Si3N4-capped polymetal structure is thought to be extremely useful to obtain higher density and higher performance LSIs. However, when a low-pressure chemical vapor deposition (LP-CVD) Si3N4 film was deposited on W, granular growth of Si3N4 was observed. We investigated this phenomenon and found the granular growth to be strongly dependent on oxidation of the W surface. We also demonstrated two methods for suppressing the granular growth.
Miniature High Intensity Microwave Ion Source
Authors: Yoshida Yoshikazu
Published: October 2002

A small microwave ion source has been fabricated from a closed magnetic circuit
with a gas nozzle placed at one end. The source has an overall length of 25 mm, a
diameter of 34 mm, and a mass of about 100 g. The ion beam current is in excess of 0.4 mA
at an extraction voltage of 3 kV and at microwave powers of less than 30 W. A
low-pressure and high-density microwave ion/plasma source is created. This source is
promising for molecular-beam epitaxy (MBE) and other ultra-high-vacuum (UHV)
applications.
Suppression of Transient Enhanced Diffusion by Local-Oxidation-Silicon-Induced Stress
Authors: Okuno Masaki , Aoyama Takayuki , Nakamura Satoshi , Arimoto Hiroshi , Horiuchi Kei
Published: October 2002

We evaluated the transient enhanced diffusion (TED) of boron on
two different local oxidation silicon (LOCOS) structures. Boron
profiles were measured by secondary ion mass spectroscopy (SIMS)
sputtering from the back surface of the wafers to eliminate any
effects caused by uneven surfaces of the LOCOS structures. To evaluate
the TED at the surface, we also measured the threshold voltage
roll-off of n-type metal-oxide-semiconductor transistors. The TED of
boron was suppressed for the LOCOS structure with a high mechanical
stress.
Fabrication of High-Resolution and High-Aspect-Ratio Patterns on a Stepped Substrate by Using Scanning Probe Lithography with a Multilayer-Resist System
Authors: Ishibashi Masayoshi , Sugita Nami , Heike Seiji , Kajiyama Hiroshi , Hashizume Tomihiro
Published: October 2002

The high-resolution and high-aspect-ratio resist-patterning method using a trilayer-resist
system with atomic force microscopy (AFM) lithography is described. This system consists of a
high-resolution negative-type resist as a top layer, p-Si as an intermediate layer, and an organic
resist as a bottom layer. Since the bottom layer planarizes the surface, the patterns can be
fabricated on a stepped surface. Using this method, we successfully fabricate 50-nm-wide and 340-nm-thick line-and-space resist patterns on a 200-nm-stepped substrate.
Characteristics of Narrow Channel MOSFET Memory Based on Silicon Nanocrystals
Authors: Shi Yi , Saito Kenichi , Ishikuro Hiroki , Hiramoto Toshiro
Published: October 2002

Metal-oxide-semiconductor field-effect transistor (MOSFET) memory devices with
silicon-nanocrystal-based floating gates on a narrow channel have been fabricated.
Electrical measurements have been performed in the temperature range of 20–300 K for
devices of various channel dimensions. Large threshold voltage shifts are obtained, being
obviously dependent on channel width, and independent of channel length. It is
experimentally found that the threshold voltage shift and charge retention characteristics
are almost independent of temperature. Furthermore, single electron charge/discharge
processes are observed in the device with the narrowest channel.
High-Performance Accumulated Back-Interface Dynamic Threshold SOI MOSFET (AB-DTMOS) with Large Body Effect at Low Supply Voltage
Authors: Takamiya Makoto , Saraya Takuya , Duyet Tran Ngoc , Yasuda Yuri , Hiramoto Toshiro
Published: October 2002

A high-performance accumulated back-interface dynamic threshold
silicon-on-insulator metal-oxide-semiconductor field effect transistor
(AB-DTMOS) with a large body effect at low supply voltage
(V
dd< 0.5 V)
is proposed for low-power applications.
In AB-DTMOS, the back interface
between the non-doped thin SOI and the buried oxide is accumulated by a
large negative substrate bias, and the gate electrode is connected to this
electrically induced body.
AB-DTMOS realizes an ideal low/ultrahigh
step channel profile electrically and achieves the maximum body effect.
At fixed V
th, the body effect factor (γ) of AB-DTMOS is
twice as
large as that of the conventional uniformly doped channel DTMOS,
because the channel depletion layer width of AB-DTMOS is half
that of the conventional DTMOS.
Experimental results show a steep
subthreshold slope, a high current drive due to a large V
th shift,
and a suppressed short channel effect.
Fabrication of 40–150 nm Gate Length Ultrathin n-MOSFETs Using Epitaxial Layer Transfer SOI Wafers
Authors: Ishii Kenichi , Suzuki Eiichi , Kanemaru Seigo , Maeda Tatsuro , Tsutsumi Toshiyuki , Nagai Kiyoko , Sekigawa Toshihiro , HiroshiHiroshima HiroshiHiroshima
Published: October 2002

We have successfully fabricated 40–150-nm-gate-length ultrathin silicon-on-insulator
(SOI) n-channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) using
SOI wafers prepared by the epitaxial layer transfer technique (ELTRAN). A highly
suppressed threshold voltage roll-off characteristic is demonstrated in the 40 nm device
with an ultrathin (11 nm) SOI channel layer. It is observed that ΔV
th is small, only 0.2 V, as compared to the value in the case of a long-gate-length (150 nm) device. The
remarkable effectiveness of an ultrathin SOI channel in suppressing the short-channel
effect is experimentally confirmed.
A New Merged Bipolar-MOS Transistor in a Silicon on Insulator Structure
Authors: Zheng Yue-sheng , Asano Tanemasa
Published: October 2002

A new metal-oxide-silicon (MOS)/bipolar merged transistor
structure in a silicon on insulator (SOI), which has a MOS structure
with a built-in bipolar mechanism, is proposed. The transistor has a
frame of a metal-oxide-silicon field-effect-transistor (MOSFET) having
the gate at the bottom. A vertical bipolar transistor is built in the
drain region by introducing an opposite-type impurity through a
polycrystalline silicon buffer layer. Implementation of the device in
an SOI structure avoids parasitic effects such as the latch-up, which
appears when a merged structure is used to construct a complementary
circuit. A two-dimensional device simulation shows the current
amplification property of the merged transistor, while also revealing
the critical design parameter for successful operation. A test device is
fabricated using a process which employs a wafer bonding and
polish-back technique. The results prove the feasibility of the
proposed device.
Highly Improved Electrical Properties of Diamond Metal-Insulator-Semiconductor Field-Effect-Transistor Prepared by Ultrahigh Vacuum Process
Authors: Yun Young , Maki Tetsuro , Tanaka Hiroyuki , Kobayashi Takeshi
Published: October 2002

In order to prevent oxygen contamination of the diamond surface as much as possible during the device process, a diamond metal-insulator-semiconductor field-effect transistor (MISFET) was fabricated by the ultrahigh-vacuum (UHV) process as well as the reduced-oxygen process, and its electrical properties were investigated in detail. Compared with conventional diamond FETs, the MISFET exhibited great improvement in electrical properties. The observed effective mobility (µeff) was 400 cm2/V·s at room temperature, which is the highest value obtained to date for the diamond FET at room temperature. According to the drain conductance G
D vs surface state density N
SS(G
D-N
SS) relation derived in this work, it was found that the surface state density of the MISFET was decreased to a great extent (∼1010/(cm2·eV)) in comparison with those of conventional diamond FETs.
Reactive Ion Etching of GaN and AlxGa1-xN Using Cl2/CH4/Ar Plasma
Authors: Basak Durga , Yamashita Kenji , Sugahara Tomoya , Fareed Qhalid , Nakagawa Daisuke , Nishino Katsushi , Sakai Shiro
Published: October 2002

Reactive ion etching (RIE) of p-GaN and p-Al
x
Ga1-x
N has been investigated
using Cl2/CH4/Ar plasmas in the conventional RIE technique. It has been found that
variation of CH4 percentage in gas mixtures leads to changes in the etch rate of both p-GaN and p-Al0.15Ga0.85N. The maximum etch rate for p-GaN has been found to be 257 nm/min in Cl2/Ar plasma containing 2.5% CH4 and the value is 170 nm/min for p-Al0.15Ga0.85N in Cl2/Ar plasma containing 10% CH4. With increasing rf power, the etch
rates for p-GaN and p-Al0.15Ga0.85N reach as high as 433 nm/min and 255 nm/min
respectively. Under optimum conditions of gas composition, radiofrequency (rf)
power, and temperature, an anisotropic and smooth etch profile is obtained. The
etched surface exhibits small roughness.
Signal Propagation Characteristics in Polyimide Optical Wave-guide with Micro-Mirrors for Optical Multichip Module
Authors: Kuwana Yasuhiro , Hirose Akinori , Kurino Hiroyuki , Koyanagi Mitsumasa
Published: October 2002

In order to develop key technologies for a multichip module with optical interconnection, a test module using polyimide optical
waveguides (POWs) with micro-mirrors and a photodiode array was
successfully fabricated.
Through the fabrication of this test module, we developed such basic
technologies as POW formation, vertical optical coupling with
micro-mirrors buried in POWs, chip bonding with copper bumps, and so on.
The signal propagation in POWs was characterized by the detection of
vertical output signals at micro-mirrors. From these characteristics,
the transmission loss caused by passing a mirror was evaluated to be
0.16 dB.
A Generalized Model for Resolution-Dependent Roughness Measured by an Optical Profiler for Optical Surfaces
Authors: Furukawa Masakazu , Kitagawa Hideo , Fukuda Yasuaki , Kohno Tsuguo
Published: October 2002

In a recent paper, we proposed a model for the dependence of
roughness on the resolution that was determined by an objective
of an optical profiler, when surface grain diameter was smaller
than the resolution. However, the model does not take into
account the effect of waviness beneath surface grains whose
wavelengths are larger than the resolution. The model is
generalized by introducing terms that include the waviness. The
area of a large cell with resolution determined by a
low-magnification (SX) objective is adjusted to R
2-times
the area of a small
cell with resolution determined by the high-magnification (LX)
objective, where R is the ratio of the large cell area defined by
the resolution of the SX objective to the small cell area defined
by the resolution of the LX objective. If the wavelengths of the
waviness and the diameters were random, the optical height in the
large cell and R
2-times the small cell would be divided into an
invariable portion that is common to both large and small cells,
and into the variable portions that are inherent to large and
small cells. Finally, a new model is obtained as a result of
multiplying the old model by a root term that takes the effect of
waviness into account. The new model agrees well with the
experimental results.
A New Micromachining Technique with (111) Silicon
Authors: Lee Sangwoo , Park Sangjun , Cho Dong-il
Published: October 2002

A new micromachining technology using (111)-oriented silicon is developed. This technology allows advanced surface micromachining with the advantages of using bulk silicon. It utilizes reactive ion etching (RIE) for patterning of microstructures to be released from the substrate, followed by aqueous alkaline etching of bulk silicon under the patterns to release the microstructures. The release etch utilize the high etch selectivity of {111} planes to {100} and {110} planes, and therefore, large plates can be released without additional etch holes, and very smooth and clear undersurfaces and substrate support surfaces can be micromachined.
Annealing Effect of ZnSe:N/ZnSe Grown by Metalorganic Chemical Vapor Deposition
Authors: Miki Takeshi , Wang Jifeng , Omino Akira , Isshiki Minoru
Published: October 2002

High-quality nitrogen-doped ZnSe (ZnSe:N) epitaxial layers were grown on ZnSe
substrates in a low-pressure metalorganic chemical vapor deposition (MOCVD) system
under optimum growth conditions using hydrogen as a carrier gas and ammonia as a
dopant source. In order to enhance the activation efficiency of nitrogen in ZnSe epitaxial
layers, ZnSe:N/ZnSe was annealed in melted zinc using the rapid thermal annealing
technique. The dependence of net acceptor concentration on annealing duration, VI/II
flux ratio, and ammonia flux was examined. The highest net acceptor concentration value
calculated from capacitance–voltage (C–V) measurements reached
2×1017 cm-3. This is
the highest value obtained so far for ZnSe homosystem epitaxial layers grown by the
MOCVD method.
Tunable Mid-Infrared Generation by Difference Frequency Mixing in KTiOAsO4
Authors: Bhar G. C. , Kumbhakar P. , Chatterjee U. , Das S.
Published: October 2002

Tunable mid infrared radiation in the range 2.6 to 5.2 µm
is generated in a flux grown KTiOAsO4 crystal by
noncollinear difference frequency mixing of Nd:YAG second harmonic and
the same pumped dye laser radiations as input fundamental radiation
sources and with the generated infrared source the infrared absorption
spectra of polythene sheets have been studied.
Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition of SiO2 and GeO2–SiO2 Films for Optical Waveguides Using Tetraethylorthosilicate and Tetramethylgermanium
Authors: Hattori Tetsuya , Semura Shigeru , Akasaka Nobuhiro
Published: October 2002

SiO2 and GeO2–SiO2 films have been deposited by employing inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD) from tetraethylorthosilicate (TEOS) and oxygen
discharge using tetramethylgermanium (TMGe) as a dopant. A pure SiO2 film deposited with
TEOS:O2 at a flow rate ratio of 17% and an operating pressure of 5 Pa showed a low wet-etching rate
of 114 nm/min approaching that of a thermally grown oxide. Ge doped SiO2 films were deposited at
various TMGe flow rates, and it was found that Ge was incorporated into the film as a replacement
for Si. The refractive index of the film is in proportion to the Ge content in the film. Fourier transform
infrared (FTIR) analysis confirmed that there were few O–H and C–H defects in the films. Optical
waveguides were fabricated using ICP-CVD and reactive ion etching (RIE). A propagation loss of
0.027 dB/cm at 1.55 µm was achieved for the optical waveguide by using GeO2–SiO2 film as the core
layer.
Spontaneous Fluctuation between Symmetric and Buckled Dimer Domains of Si(100) at 80 K
Authors: Hata Kenji , Kimura Tomohiko , Miyake YasuyukiSainoo , Morita Ryuji , Yamashita Mikio , Shigekawa Hidemi
Published: October 2002

At 80 K, not all the dimers of Si(100) appear buckled in the scanning tunneling
microscopy (STM) images but a certain number of the dimers are observed in a symmetric
configuration. We report on observations of a two-dimensional spontaneous fluctuation of
the symmetric⇔buckled dimer domains at some particular locations. We interpret the
spontaneous fluctuation to be induced by the competition of several
antiphased c(4×2)
buckled domains to expand. The fluctuation of domains was interpreted by two
mechanisms: a fast switching between buckled dimer domains; and symmetric dimers
induced by migration of P defects.