bluuebunny/crossref_metadata_2025 huggingface dataset:
Metalorganic Chemical Vapor Deposition Growth of GaN Using a Split-flow Reactor
Authors: Yamashita Youji , Sato NaochikaHorio , Ebisutani Takashi , Taniguchi TeruyukiKamiya , Kingo Yasuro , Imagi Shinichi , Kato Kazuhisa
Published: October 2002

We developed a split-flow reactor for growing epitaxial films in an atmospheric
metalorganic chemical vapor deposition (MOCVD), where the reactant gas stream is
separated from the wall by a buffer gas stream. This reduces the use of reactant gases,
thereby minimizing operating costs. Wall deposits were also minimized. The reactor was
fan-shaped with an inclined upper wall. To reduce the interdiffusion of the reactant and
buffer streams, the substrate was placed upstream, near the gas inlet. The downward
inclined upper wall maintains a constant cross sectional area and therefore constant velocity
in the radial direction. The result is that the flow is stabilized. We demonstrated this reactor
by growing undoped GaN epitaxial films on a two-inch substrate using a two-step growth
process, where the epitaxial layer is grown on a buffer layer. The highest quality GaN films
were grown using a buffer stream of H2, but the lowest consumption of the reactant gases
was achieved using a buffer stream of N2.
Deposition Rate and Gap Filling Characteristics in Cu Chemical Vapor Deposition with Trimethylvinylsilyl Hexafluoro-acetylacetonate Copper (I)
Authors: Kobayashi Akiko , Sekiguchi Atsushi , Okada Osamu
Published: October 2002

To obtain a low-resistivity material and good gap-filling characteristics in the interconnect metallization process for advanced ULSI devices, we investigated the deposition rate and gap-filling characteristics of Cu chemical vapor deposition. We used trimethylvinylsilyl hexafluoro-acetylacetonate copper (I) as the source at deposition temperatures from 150 to 240°C and source partial pressures (P
s) from 16 to 270 Pa. The deposition rate was studied as functions of the deposition temperature and P
s. The deposition rate increased as the temperature increased, but gap filling simultaneously deteriorated under constant P
s. To obtain good gap filling, P
s should be increased, but P
s is restricted by the saturated vapor pressure. Interpretations are given for gap-filling characteristics from the viewpoint of the deposition mechanism. It is concluded that the maximum deposition rate with excellent gap filling is regulated by the source vapor pressure. We succeeded in satisfactorily filling a hole of an aspect ratio of 5.5 at 200 Pa of P
s and at 170°C with the deposition rate of 40 nm/min. To obtain the same hole filling characteristic at a deposition temperature of 180°C, P
s should be raised to 250 Pa and the deposition rate should be 60 nm/min.
Electron Spin Resonance Studies on Spots with Brown Rims on a Vitreous Silica Surface formed by a Silicon Melt
Authors: Sugiyama Yoshio , Tamura Motonori , Ikari Atsushi
Published: October 2002

Vitreous silica plates were immersed separately in a silicon melt at 1460°C for 4 h and 25 h,
respectively in argon atmosphere. Electron spin resonance (ESR) and optical microscopy
observations showed that the paramagnetic species (g=2.0049, peak-to-peak line width (ΔH
pp)
=7.0 G) existed at the center and the periphery of the spots with brown rims in the silica plate
subjected to 4 h immersion. It was revealed that both silicon oxide (SiO1.49) and silicon monoxide
(SiO1.04) have silicon dangling bonds (e.g., •Si≡Si3, •Si≡Si2O, and •Si≡SiO2) which have
ESR parameters (g=2.0048, ΔH
pp=7.5 G). The paramagnetic species in the spots with brown
rims were estimated to be the silicon dangling bonds (e.g., •Si≡Si3, •Si≡Si2O, and •Si≡SiO2) in the silicon monoxides.
Tunable Ultrashort Pulse Generation from a Waveguided Laser with Premixed-Dye-Doped Plastic Film
Authors: Yuji Oki Yuji Oki , Katsuya Ohno Katsuya Ohno , Mitsuo Maeda Mitsuo Maeda
Published: October 2002

A highly compact ultrashort pulse generator is proposed and
demonstrated with a poly-methylmethacrylate (PMMA) waveguide doped
with a mixture of laser dye (Rhodamine 6G) and saturable
absorber (DODCI). A series of spikes with a pulse duration of
20–30 ps was generated by a distributed feedback dye laser
pumped by a ns Nd:YAG laser. First, the spikes were shortened by
passive Q-switching effect of the saturable absorber. Then they were
compressed to 9 ps FWHM by passing a pulse compressor having an
alternative chain of amplifier and saturable absorber integrated on
the same waveguide. Performances of both devices were evaluated by
calculation and confirmed experimentally.
The Infrared Transmission of Pb0.1Ca0.9La2S4 Pellets in the 2.5–14 µm Region
Authors: Tsay Bor Jou , Wang Li Hsing , Hon Min Hsiung
Published: October 2002

Highly sinterable submicron Pb0.1Ca0.9La2S4 (PCLS) powders were
prepared by sulfidizing lead calcium and lanthanum alkoxides at 500°C under
CS2 gas for 8 h and then in a pure H2S atmosphere for 16 h at 650–950°C
for application in an infrared transmitting window material for the 8–14 µm
wavelength region. The transmittance at 2.5 µm of the pellet densified from the PCLS
powder was 8 times higher than that from the β-La2S3 powder. The characteristic
absorption bands of sulfite and sulfate at 9.2 and 11 µm, respectively, were reduced in
the pellet by eliminating the oxygen content in the PCLS powder by flowing
chlorine gas into the furnace at 600°C for 1 h and then sulfidizing the powder at
950°C for 16 h. It was shown that 1100°C was the optimum hot pressed sintering
temperature for obtaining a higher transmittance ceramic.
Acid Rain Affecting the Electrical Properties of Outdoor Composite Dielectric Materials
Authors: Wang Xinsheng , Kumagai Seiji , Yoshimura Noboru
Published: October 2002

Acid rain is precipitation with acidity, i.e., pH, below 5.6. There is an increasing interest in the degradation of the electrical properties of outdoor composite dielectric materials under severe contaminant conditions such as acid rain. In this study, the degradation effects of acid rain on the outdoor composite dielectrics are investigated by accelerated aging due to artificial acid rain. Based on the investigation of acid rain, the composition of artificial acid rain is chosen to agree with the actual composition of precipitation. The surface potential, breakdown voltage, tracking resistance, and surface discharge current of dielectric materials are studied. Furthermore, the degradation mechanisms of electrical properties of composite dielectrics are discussed by investigating the degradation of the chemical and physical microstructures of material surface using Fourier transform infrared (FTIR), the X-ray diffraction spectrum (XDS), and the metalloscope. Experimental results show that the outdoor polymeric dielectrics suffer severely and degrade due to acid rain so that their surface electrical properties deteriorate after aging. The erosion, by acid rain, of the energized dielectric materials is larger than that of outdoor materials used for other purposes.
Structure Change of Glass-like Carbon with Heat Treatment, Studied by Small Angle X-Ray Scattering: I. Glass-like Carbon Prepared from Phenolic Resin
Authors: Nishikawa Keiko , Fukuyama Katsuya , Nishizawa Takashi
Published: October 2002

For glass-like carbon samples made from phenolic resin at 950°C and thereafter obtained at
various heat-treatment temperatures (HTT), structural studies were carried out by means of small
angle X-ray scattering (SAXS). The scattering patterns of the samples heat treated at temperatures
higher than 1800°C are significantly different from the ones obtained at lower temperatures. The
temperature of about 1800°C seems to be a boundary of different carbonization mechanism. Wide
angle X-ray scattering (WAXS) experiments were also performed for the same samples. From the
SAXS and WAXS results, it is suggested that the carbonization of glass-like carbon
(non-graphitizing carbon) occurs in a similar manner as the graphitizing carbon such as coke,
though the sizes of the graphite crystallites are different. The increase of HTT causes the ordering
of the planes of small graphite crystallites and the growth of closed pores. The Fourier transform
analysis shows that glass-like carbon heat-treated at 3000°C has pores which are nearly uniform in
size and about 60 Å in diameter.
Study of the Si(111)“1×1”–Au Surface Using Reflection High-Energy Electron Diffraction and Scanning Tunneling Microscopy
Authors: Khramtsova Elena A. , Sakai Hiroto , Hayashi Kazuhiko , Ichimiya Ayahiko
Published: October 2002

The initial stages of Si(111)–Au
interface formation have been studied using reflection high-energy
electron diffraction (RHEED),
scanning tunneling microscopy (STM) and intensity
rocking curve analysis of one-beam RHEED.
An equilibrium phase diagram of the Au/Si(111) system has been determined for
the Au coverage range of 0–0.7 monolayers and substrate temperatures
of 750–850°C.
Our RHEED data and “quench and look” STM observations show
that two different types of “1×1”–Au-stabilized surface phases
can be formed depending on the magnitude of interaction between
Au atoms.
The interaction between Au atoms was found to be
weak when they are separated by a distance of more
than about five 1 ×1 unit cells of the
Si(111) surface kept at temperatures higher than 800°C.
At different conditions, Au atoms cluster into trimers which are
assumed to form all other Si(111)–Au surface phases.
Film Characteristics of Low-Temperature Plasma-Enhanced Chemical Vapor Deposition Silicon Dioxide Using Tetraisocyanatesilane and Oxygen
Authors: Idris Irman , Sugiura Osamu
Published: October 2002

Silicon dioxide films were deposited in a parallel-plate electrode RF plasma-enhanced chemical vapor deposition (PECVD) system using hydrogen-free
tetraisocyanatesilane (TICS) and oxygen. The deposition parameters were varied
systematically, and the films were characterized by measuring infrared spectra, density,
etch rate, refractive index, and current-voltage (I–V) and capacitance-voltage (C–V) characteristics, as well as by examining their annealing behavior. At 300°C and a TICS
partial pressure ratio of 20%, a water-free and hydroxyl-group-free SiO2 film was
obtained. The film density, BHF etch rate, refractive index, resistivity, and dielectric
constant were 2.3 g/cm3, 330 nm/min, 1.46, 7×1015 Ω·cm, and 3.6, respectively. The
film quality degraded and, simultaneously, the film absorbed moisture from the
atmosphere with decreasing deposition temperature; however, the quality can be
improved by reducing TICS partial pressure. SiO2 films could be deposited even at 15°C,
and had a resistivity of about 1013Ω·cm. Infrared measurements showed that SiO2
films deposited from TICS/O2 contained less absorbed water than those deposited from
hydrogen-containing source materials at the same deposition temperature.
Linear Mode Conversion between Ordinary and Extraordinary Waves in Plasma with Large Magnetic Shear
Authors: Kazuo Minami Kazuo Minami , Akira Ejiri Akira Ejiri , Koji Tanaka Koji Tanaka , Tsuguhiro Watanabe Tsuguhiro Watanabe
Published: October 2002

Linear mode conversion between ordinary- and extraordinary-mode microwaves in plasma with large magnetic shear is analyzed numerically. The purpose of the analysis is a basic-design study of a microwave reflectometer using the mode conversion available in the fusion reactor large helical device (LHD) with large magnetic field shear created by a pair of helical windings. We call this a mode conversion reflectometer. Analysis is performed assuming a simple one-dimensional model and practical plasma parameters. The results indicate that mode conversion is sensitively affected by the density gradient near the two cutoff points. A steep gradient results in a large degree of mode conversion. In some cases, the converted amplitude becomes larger than 10% that of the incident signal. It is shown that, for steep density profiles, the interference patterns obtained by two converted (daughter) signals are applicable to the measurement of the density profile without any conventional phase detection.
Possibility of Profile Control using Compact Toroid Injection on Large Helical Device
Authors: Miyazawa Junichi , Yamada Hiroshi , Motojima Osamu
Published: October 2002

Compact toroid (CT) injection is an attractive method for central fueling into hot fusion plasmas. Induction of plasma rotation is expected by momentum input along the three-dimensional trajectories of the injected CT. The CT trajectories in the magnetic field of a large helical device (LHD) are calculated while changing the initial injection velocity and injection point, to determine the optimum conditions for CT injection into LHD. The possibility of central fueling is confirmed with a model CT with a diameter of 20 cm, 1022 m-3 electron density, and 300 km/s initial velocity, in the case of CT injection into an LHD magnetic field of 1.5 T. The input profiles of the density and the momentum obtained assuming a simple CT decay model show the potential of CT injection as a profile control method.
Effect of Duty Ratio of Driving Voltage on the Forming Process in Aging of Organic Electroluminescent Device*
Authors: Liu Xingyuan , Li Wenlian , Yu Jiaqi , Peng Junbiao , Zhao Yu , Sun Gang , Zhao Xu , Yu Yi , Zhong Guozhu
Published: October 2002

An interesting phenomenon “forming process”, namely, the rising process of luminance and
efficiency at the initial aging of organic eletroluminescent devices, was studied under constant pulse
voltage excitation with different duty ratios. The device has a conventional double-layer structure.
Tris(8-quinolinolato) aluminum (Alq) was used as the emitter layer, and poly(N-vinylcarbazole)
(PVK) was used as the hole transport layer (HTL). The increase of luminance is due to that of the
current. It was assumed that the forming process results from the redistribution of the electric field in
the organic layer due to the build up of space charge at the interfaces as well as other factors.
Confocal Microscope for Three-Dimensional Polarization Analysis
Authors: Yoshimasa Kawata Yoshimasa Kawata , Wataru Inami Wataru Inami
Published: October 2002

We present a confocal microscope for use in three-dimensional
polarization analysis. Since the pinhole before the detector eliminates
the light whose polarization is rotated by an imaging lens, the
polarization properties of specimens are observed with high contrast.
The pinhole size required to achieve high contrast is discussed.
Three-dimensional resolution of the polarization microscope is also
demonstrated.
Quantitative Measurement of the Ray Shift Aspect of Coma Aberration Utilizing Electrical Probe with Zero-Crossing Method
Authors: Nakao Shuji , Tsujita Kouichirou , Wakamiya Wataru
Published: October 2002

A novel quantitative measurement method of the ray shift
aspect of coma aberration utilizing an electrical probe is
proposed, based on the optical image calculations. The
printed width difference of two parallel lines caused by a
coma aberration is compensated by changing the mask width of
the one line and fixing that of the other. Using an
electrical probe, the printed width difference of the two
lines can be converted to the output voltage. Plotting the
voltage with the mask width difference and determining the
zero-crossing point by interpolation, the effective coma
aberration coefficient can be obtained quantitatively. The
accuracy of the measured aberration coefficient and the
minimum detectable aberration are estimated to be less than ∼0.01 λ.
Challenges to 0.1 µm Resolution Capability in ArF Single Layer Resist Process with Weak Resolution Enhancement Techniques
Authors: Takahashi Makoto , Kishimura Shinji , Ohfuji Takeshi , Sasago Masaru
Published: October 2002

We examine the resolution capability of the ArF single layer resist process with
weak resolution enhancement techniques. To do this, annular illumination and an
attenuated phase-shifting mask are applied to a high-resolution ArF single layer resist.
Such weak resolution enhancement techniques are more widely applied than strong
resolution enhancement techniques. The experimentally obtained data are correlated
with simulated aerial image contrasts to evaluate the lithographic performance under
various optical conditions. The aerial image contrast is greatly enhanced by applying
larger partial coherence in annular illumination. It is quite effective, especially for
features smaller than 0.13 µm lines and spaces. By applying the optimum condition in
annular illumination, 0.10 µm lines and spaces can be obtained even without using a
phase-shifting mask. Furthermore, from the process margin simulated with the
measured resist dissolution rates, it is expected that the ArF single layer resist process
with weak resolution enhancement can be applied in the fabrication of 0.1 µm-rule
devices.
Statistical Estimation of Power Deposition Profile in Electron Cyclotron Heated Plasmas
Authors: Makoto Iwase Makoto Iwase , Shin Kubo Shin Kubo , Hiroshi Idei Hiroshi Idei , Kunizo Ohkubo Kunizo Ohkubo , Takashi Minami Takashi Minami , John Wilgen John Wilgen
Published: October 2002

The power deposition profile by modulated fundamental electron cyclotron heating is deduced with the confidence interval derived from the statistical treatment of experimental data. The second harmonic electron cyclotron emission is used for the measurement of electron temperature that is necessary in this analysis. It is shown that the resultant deposition profile is consistent with the prediction resulting from the ray tracing calculation, including the multireflection effect at the vessel wall. The local adiabatic time scale for the thermal diffusion is derived and the propriety of the time scale in the power balance analysis is confirmed. The statistical confidence interval implies a broad profile of the power absorption. The obtained results show the necessity of using the statistical approach for analysis of the experimental data.
Mask Contamination Induced by X-Ray Exposure
Authors: Okada Ikuo , Saitoh Yasunao , Deguchi Kimiyoshi , Fukuda Makoto , Ban Hiroshi , Matsuda Tadahito
Published: October 2002

To investigate the growth of mask contamination induced by X-ray exposure, masks are exposed to X-rays using an X-ray stepper. Independent of the exposure conditions, and in the presence or absence of resist
coating, the main component of the contaminant is the salt (NH4)2SO4. On some resist-coated wafers, the
contaminant growth is governed by the volume of sulfuric materials which evaporate during exposure.
Contamination growth can be suppressed by applying a top coat to the resist, as using a resist that does not
evaporate as a sulfuric out-gas. Gases were irradiated by X-rays in order to examine the change in
environmental pollutants. In humid air, NO, NO2 and NH3 form rapidly up on X-ray irradiation. SO2 also
increases up on X-ray irradiation, and changes into H2SO4. H2SO4 easily combines with NH3 which is produced by X-ray irradiation in humid air, and turns into the salt (NH4)2SO4. Mask coating was introduced to suppress the contaminant growth. The mask coated with TiO2 layer does not show contaminant growth,
showing a drastic curtailment of contamination by the photocatalysis effect.
Implementation of Sub-150 nm Contact Hole Pattern by Resist Flow Process
Authors: Kim Jin-Soo , Choi Chang-Il , Kim Myoung-Soo , Bok Cheol-Kyu , Kim Hyeong-Soo , Baik Ki-Ho
Published: October 2002

The characteristics and performance of the resist flow process (RFP), which is one
of the contact hole (C/H) shrinking technologies, were investigated for sub-150 nm C/H patterns using KrF (λ=248 nm) lithography. A fine C/H pattern was defined by adopting optimized process parameters at a higher baking temperature than the glass transition temperature of the used matrix material. The shrinking limit of the C/H pattern was in the
range of 40–50 nm without any deformation in profile from the original C/H size, however, the bowing profile of the C/H pattern was observed in the case of a shrinking bias larger than 50 nm. It was also found that the amount of shrinkage of the C/H pattern was strongly dependent on the baking temperature, total quantity of the resist surrounding the C/H pattern, and resist thickness. When the 150 nm C/H pattern was formed by RFP from a 180 nm C/H generated by an attenuated phase shifting mask (PSM), the depth of focus (DOF) and the energy latitude (EL) were 1.6 µm and 16%, respectively, and the critical dimension (CD) uniformity in an 8-inch wafer was less than 25 nm. In this study, in spite of baking to enable resist flow, the etch selectivity of resist on silicon substrates was not changed and the C/H pattern on silicon oxide after the etching process showed a vertical profile. Based on these results, it is believed that the RFP for a sub-150 nm C/H pattern will be a very promising candidate for the mass production of gigabit devices.
Aluminum Etch and After-Corrosion Characteristics in a m=0 Helicon Wave Plasma Etcher
Authors: Ha Jae Hee , Yim Myoung-ho , Kim Jae-jeong
Published: October 2002

The etch and corrosion characteristics of stacked aluminum were investigated in a
m=0 helicon plasma etcher. Wide process margin was achieved in the aspects of Al etch
profile and selectivity of Al to photoresist. The dependence of corrosion resistance on
etch parameters was remarkably improved under the conditions of high source power,
low pressure, and no N2 addition. The sidewalls of etched Al analyzed by tunneling electron microscopy (TEM) were
composed of three different layers: an outermost layer, a middle layer, an innermost layer.
When N2 was added, the serious corrosion was caused by the high concentration of
residual chlorine captured in the dense sidewall film which mainly consists of Al–O,
Al–N, Si–O, and Si–N. It was observed that lowering the source power induced the big
increase of both Cl and Cu concentrations.
Sub-Quarter-Micron Pt Etching Technology Using Electron Beam Resist with Round-Head
Authors: Yunogami Takashi , Kumihashi Takao
Published: October 2002

Pt patterns of 0.16, 0.25 and 0.36 µm size and without a sidewall-fence were formed using dipole ring magnetron reactive ion etcher (DRM-RIE)
with round-head resist masks of 0.1, 0.2 and 0.28 µm size written by an electron beam. Critical dimension (CD) gains ranged from 50 to 60 nm,
and taper angles ranged from 72 to 75°. To realize sidewall-fence-free Pt etching with a small CD gain and large taper angle, it is important
to tune resist selectivity to an optimum. Taper angle becomes small and CD gain becomes large in the case of low resist selectivity; on the
other hand, sidewall-fence is formed in the case of high resist selectivity. Eventually, under the condition of optimum resist selectivity,
no sidewall-fence is formed and taper angle and CD gain become large and small, respectively. The optimum resist selectivity has been realized
under the conditions of low pressure, high Cl2 flow rate, and high RF power.
Electron Beam Doping in Damageless Regions of Semiconductors by the Kick-Out Mechanism (Interstitialcy and Direct Interstitial Mechanism)
Authors: Wada Takao , Fujimoto Hiroshi
Published: October 2002

It is demonstrated that the interchange of impurity foreign atoms between
substitutional and interstitial sites occurring during the diffusion of impurities in
damage-free Si and GaAs due to the electron beam doping by superdiffusion is
controlled by the kick-out mechanism. Their diffusion profiles in semiconductors are in
good agreement with the exact solution of Seeger's theory of the
kick-out diffusion.
Method for Evaluating the Interface of Semiconductor Heterojunctions Using a Free Electron Laser
Authors: Nishi Kazuhisa , Ishizu Akira , Nagai Akio , Tomimasu Takio
Published: October 2002

The method for evaluating the interface of semiconductor heterojunctions using
the free electron laser internal photoemission (FEL-IPE) technique is presented. The
nature of the interface in semiconductor heterojunctions plays an important role for
determining the behavior and performances of an entire class of nanosemiconductor
devices. It is indicated that the measurement using FEL-IPE makes it possible to
determine the band discontinuities of semiconductor heterojunctions more precisely.
Microprobe Analysis of Pt Films Deposited by Beam Induced Reaction
Authors: Park Yang-Keun , Takai Mikio , Lehrer Christoph , Frey Lothar , Ryssel Heiner
Published: October 2002

The localized Pt deposition by 30 keV Ga+ focused ion beam (FIB) or 10 keV electron beam (EB) induced reaction has been investigated using micro-RBS spectra and RBS mapping images by a 300 keV Be2+ microprobe with a beam spot size of 80 nm. The amount of Pt atoms increased with increasing ion dose due to the decomposition of precursor gas for FIB irradiation. Residual Ga atoms were found to be distributed at and near within 1.5 µm the deposited area due to the implantation from the Ga FIB and redeposition from the processed area, while low-Z elements such as C and O distributed at and around the processed areas by about 10 µm due to the adsorbed molecules of precursor gas after FIB processing. Micro-RBS spectra for EB induced deposited area show that the thickness of Pt layer is considerably less than that obtained by FIB due to the reduced deposition rate and the amount of Pt atoms at the boundary area was also less than that obtained by FIB, since the intensity profile of the electron beam was much shallower than that of FIB.
The Vapor Phase Deposition of Fluorocarbon Films for the Prevention of In-Use Stiction in Micromirrors
Authors: Park Jin-Goo , Kwon Myong-Jong , Lee Sang-Ho , Lee Kang-Kuk , Kim Yong-Kweon , Shin Hyung-Jae
Published: October 2002

The purpose of this study was to explore the vapor-phase (VP) deposition of fluorocarbon (FC) films for the prevention of in-use stiction in a microelectromechanical system (MEMS). Liquid sources (3M Co.'s FC722 and FC40) were used to deposit FC films on sputter coated Al surfaces after wet treatment (73% H3PO4, 4% HNO3, 3.5% CH3COOH, 19.5% deionized water) and O2and O2/CF4plasma treatments. A vacuum oven, set at 110°C, was used for the experiment. The deposition was carried out at a pressure of 4.5×10-2Torr for 40 min followed by the annealing at 300 Torr for 20 min in N2to obtain the highest water contact angles on Al. The wet treatments of the surfaces resulted in higher contact angles and thicker FC films than those obtained by the plasma treatments. Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) analysis showed the strong CF2stretching bands in the 1100–1300 cm-1region. Atomic force microscopy (AFM) analysis revealed the changes of surface morphology before and after FC deposition. Also no stiction of micromirrors was observed when fluorocarbon films were deposited on them even after 2×108touch-down cycles.
Monolithic Fabrication of Electroplated Solenoid Inductors Using Three-Dimensional Photolithography of a Thick Photoresist
Authors: Yoon Jun-Bo , Han Chul-Hi , Yoon Euisik , Kim Choong-Ki
Published: October 2002

A novel and high-yield fabrication process has been devised for
monolithic integration of solenoid inductors. In order to simplify the
fabrication steps, we decompose the solenoid inductor into two parts, bottom conductor lines
and air bridges. The air bridge is formed as a single body during a single electroplating step. This single-step fabrication of the air bridges is possible by forming a three-dimensional (3D) photoresist mold using multiple exposures with varying exposure depths, followed by a single development step, which realizes the 3D latent image of the unexposed volume in the photoresist. We have successfully fabricated solenoid inductors with and without a magnetic core using this process. This process is easy and simple, so that one can significantly improve the fabrication yield over that achieved by conventional methods. Also, this process has good compatibility with the integrated circuit (IC) process owing to a low process temperature (<120°C) and the monolithic feature.
Novel Fabrication of Comb Actuator Using Reactive Ion Etching of Polysilicon and (110) Si Anisotropic Bulk Etching in KOH
Authors: Lim Hyung-Taek , Kim Yong-Kweon
Published: October 2002

A bulk-micromachined interdigitated comb actuator suspended by surface-micromachined polysilicon springs is proposed and fabricated for excitation of resonating motion. The excitation force electrically generated by the interdigitated (110) Si comb pair of 420 µm height is more effective than that obtained using a comb pair with 3–5 µm height fabricated by polysilicon micromachining. The interdigitated comb finger array, whose geometry is 420 µm high, 20 µm wide and 5 µm from the neighboring interdigitated comb finger, is fabricated by anisotropic bulk etching of 420-µm-thick (110) Si in KOH. A 5-µm-thick phosphorous-doped low pressure chemical vapor deposition (LPCVD) polysilicon film is used for the fabrication of flexures of the actuator, using reactive ion etching. The double-sided aligned fabrication technique accomplishes not only polysilicon flexure formation on both sides of the actuator but also the removal of two slant (111) planes in concave corners of the (110) Si structure, which have limited the interdigitated comb actuator design on (110) Si.
A Complementary Metal Oxide Semiconductor (CMOS) Compatible Capacitive Silicon Accelerometer with Polysilicon Rib-Style Flexures
Authors: Kim Seokyu , Yee Youngjoo , Kim Hyeoncheol , Chun Kukjin , Hong Ikpyo , Lee Jongwon
Published: October 2002

A silicon-based capacitive accelerometer with bulk silicon proof mass, polysilicon rib-style flexures, and detection circuits is fabricated and tested. A complementary metal oxide semiconductor (CMOS) compatible doping and annealing process for 2-µm-thick polysilicon used as a rib-style flexural beam is developed to optimize the trade-off between the mechanical properties and electrical requirements. According to the anisotropic etch simulation and experimental results, we designed a convex corner compensation pattern and fabricated the proof mass. The open-loop gain of the fabricated switched capacitor integrator (SCI) is more than four thousands, and the common mode range is from 0.8 V to 4.5 V. The fabricated accelerometer has sensitivity of 300 mV/g and capacitance change is 0.36 pF/g.
Improved Automatic Alignment of Pinhole Integrated with Photodiode
Authors: Minoru Sasaki Minoru Sasaki , Yuji Arai Yuji Arai , Wataru Kamada Wataru Kamada , Kazuhiro Hane Kazuhiro Hane
Published: October 2002

The spatial filter of a Si micromachined pinhole integrated with photodiodes is fabricated.
The photodiode cells placed around the center pinhole can detect the relative position between the incident beam spot and the pinhole.
The automatic alignment of the pinhole was realized using a feedback control based on the position signal obtained from the photodiode cells.
In our previous study, the alignment accuracy achieved was ±0.5 µm for a pinhole of 50 µm diameter.
In this study, the design is improved by reducing the separation length between the surrounding photodiode cells.
An alignment accuracy of ±0.03 µm was demonstrated.
Direct Transport Measurements through an Ensemble of INAS Self-assembled Quantum Dots
Authors: Koo Jung Suk , Ho Choi Bum , Il Kim Suk , Kyeong Hyon Chan , Don Min Byung , Woo Hwang Sung , Ho Park Jung , Kyu Kim Yong Kim , Ki Min Suk
Published: October 2002

Direct transport measurement results of an InAs self-assembled quantum dot system
have been reported. The differential conductance characteristics measured from the
metal-semiconductor-metal diodes incorporating InAs self-assembled quantum dots
show conductance peaks. The energy spectrum of the dots is obtained from the peak
positions.
Fabrication of a Separation by Implantation of Oxygen Silicon Nano-Gap Using Thin Film Stress
Authors: Park Dong-Il , Zang Woo-Jae , Lee Jong-Hyun , Lee Jung-Hee , Hahm Sung-Ho
Published: October 2002

We have fabricated and controlled a novel nanometer scale silicon gap in a separation by implantation of oxygen (SIMOX) structure using the thin film stress generated during high temperature annealing and cooling, and then elucidated the formation mechanism and crystal orientation dependency of the gaps. The technique is very simple and controllable in shaping a wedge type nano-structure with a several hundred-nanometer gap. The fabricated structure has a 190 and 250 nm narrow gap with 2 µm and 11 µm side etching of the buried SiO2, respectively.
In Situ Optical Monitoring of Hydrogen Chemisorption on the GaAs(111)B Ga Surface
Authors: Koukitu Tetsuya Taki
Published: October 2002

The hydrogen chemisorption on the GaAs(111)B Ga surface is investigated under atmospheric pressure using the surface photoabsorption (SPA) and temperature-programmed desorption (TPD) methods. The SPA signal change shows the existence of two kinds of hydrogen-terminated surfaces, monohydride and trihydride surfaces, depending on the partial pressure of hydrogen. In both surfaces, hydrogen in the carrier gas reacts dissociatively with Ga atoms on the (111)B surface, and the desorption of hydrogen occurs via the reverse reaction in the inert carrier gas. It is shown that the surface coverages of hydrogen on the surfaces are well explained by the Langmuir equation.
Development of Stable a-Si Solar Cells with Wide-Gap a-Si:H i-layers Deposited by an Inert Gas Plasma Treatment Method
Authors: Maruyama Eiji , Hishikawa Yoshihiro , Tanaka Makoto , Kiyama Seiichi , Tsuda Shinya
Published: October 2002

The stability against light soaking of wide-gap hydrogenated amorphous silicon (a-Si:H) films and a-Si solar cells deposited by a newly developed inert gas plasma treatment method has been systematically investigated for the first time. The defect density (N
D) of a-Si:H films with an optical gap (E
opt) of 1.64 eV deposited by the inert gas (He, Ar, Xe) plasma treatment method was measured by a constant photocurrent method (CPM). E
opt was determined by (αhν)1/3 versus hν plots. It was found that the inert gas plasma treatment method is capable of decreasing the initial and stabilized N
D of the wide-gap a-Si:H films to a greater extent than that achieved by the 100% SiH4 process. In particular, the wide-gap a-Si:H film deposited using an Ar plasma treatment showed low initial and stabilized N
D of about 8×1014 cm-3 and 9×1015 cm-3, respectively, which are comparable to those of our optimized a-Si:H with E
opt∼1.57 eV deposited from 100% SiH4. It was also found that this deposition method is able to improve the stability of a-Si solar cells with wide-gap i-layers when compared to the 100% SiH4 process. Experimental results indicate that this deposition method can suppress the fast light-induced degradation which is probably caused by the light-induced defects that are difficult to recover by thermal annealing at ∼150°C.
Measurements of a Small Signal Gain Coefficient of Flashlamp Pumped Cr,Tm:YAG and Cr,Tm,Ho:YAG Lasers
Authors: Yoichi Kemmochi Yoichi Kemmochi , Fumio Matsuzaka Fumio Matsuzaka , Hiroshi Hara Hiroshi Hara
Published: October 2002

We measured the small signal gain coefficient of Cr,Tm:YAG and Cr,Tm,Ho:YAG flashlamp pumped lasers, varying the rod temperature (5–25°C) and pumping energy density (51.3–85.9 J/cm3). The maximum small signal gain coefficients measured for these lasers were 0.144 cm-1 and 0.234 cm-1, respectively. The Cr,Tm,Ho:YAG laser was found to have a two-fold higher gain, and to be more temperature-sensitive than the Cr,Tm:YAG laser.
Resonant Raman Scattering and Its Correlation to Exciton Luminescence in AgGaS2
Authors: Masami Susaki Masami Susaki , Kazuki Wakita Kazuki Wakita , Nobuyuki Yamamoto Nobuyuki Yamamoto , Eiji Niwa Eiji Niwa , Katashi Masumoto Katashi Masumoto
Published: October 2002

Resonant Raman scattering and luminescence are studied for secondary emission in AgGaS2 using polarized excitation. At 8.6 K, a series of multiple phonon Raman lines are observed in addition to the ordinary luminescence bands due to free exciton, bound exciton and shallow donor states. The usual selection rule of optical transition is valid for the two radiation components in the vicinity of the band edge region. The intensities of both first order Raman and luminescence features are enhanced in the same energy region when the excitation energy is slightly higher than the free exciton energy. The resonance of this scattering from longitudinal optic E-phonons exhibits a temperature-dependent enhancement correlated with the thermal shift of the exciton gap and in the emission energies, especially of the free and bound excitons at low temperatures. The damping constants and relative strengths of the resonances at the luminescence states are determined and compared with those at the intrinsic exciton level.
Microwave Dielectric Properties and Microstructures of (Ba1- xPb x)O·La2O3·4.7TiO2 Ceramics
Authors: Lee Cheng Chung , Lin Pang
Published: October 2002

The evolution and correlation of microwave dielectric properties and microstructures were investigated systematically for ceramics composed of (Ba1-x
Pb
x
)O·La2O3·4.7TiO2 (0≤x≤0.5) and sintered at temperatures between 1250° and 1350°C. Major phase BaLa2Ti4O12 and minor phases Ba4Ti13O30 and La4Ti9O24 present in the samples were identified. A Pb additive generally reduced the dielectric constant and enhanced the quality factor of the specimens, except for that prepared at 1250°C, which exhibited the opposite trends. Appreciable replacement of Ba2+ by La3+ and Pb2+ ions was found in the major phase and it effectively reduced the temperature coefficient of resonant frequency τf to 3 ppm/°C. The observed variations of microwave properties were interpreted based on microstructural and composition analysis.
Phase Transition between Microemulsion and Lamellar Phases in a C12E5/Water/n-octane Amphiphilic System
Authors: Ghosh Swapan K. , Komura Shigehiro , Matsuba Junichi , Seto Hideki , Takeda Takayoshi , Hikosaka Masamichi
Published: October 2002

A ternary amphiphilic system consisting of water, n-octane and C12E5 has been studied by small angle X-ray scattering (SAXS) to elucidate the mechanism of phase transition between lamellar and microemulsion phases. SAXS profiles in the region between lamellar and microemulsion phases show two distinct peaks, which indicate that different structures coexist. These structures change continuously as transition goes on, which is in good agreement with the lever rule in phase diagram. The transition behavior has been explained as a result of the change of curvatures of the interfacial film as a function of temperature and subsequent change of bending elastic energy. A boundary of the coexistence region is determined by the double tangent construction for the free energies of the microemulsion and lamellar phases.
ArF-Excimer-Laser Annealing of 3C-SiC Films
Authors: Mizunami Toru , Toyama Naotake
Published: October 2002

Boron-doped 3C-SiC films grown by thermal chemical vapor deposition (CVD) at 950°C using an infrared lamp were annealed using an ArF excimer laser (193 nm). The crystal quality was studied using reflection high-energy electron diffraction (RHEED), and the surface morphology was studied using a scanning electron microscope (SEM). It was demonstrated that both the crystal quality and the surface morphology were improved after irradiation of three laser pulses with an energy density of 1.4–1.6 J/cm2 per pulse.
The Properties of Lead Titanate Thin Films Derived from a Diol-Based Sol–Gel Process
Authors: Wang Chih-Ming , Chen Ying-Chung , Lee Maw-Shung , Wu Ju-Wen , Chiou Chien-Chih
Published: October 2002

The La-modified lead titanate (PLT) thin films were deposited on Pt/SiO2/Si substrates by spin coating with sol–gel processing. 1,3-propandiol was used as solvent to minimize the number of cycles of spin coating and drying processes to obtain the desired thickness of high quality thin film. By changing the La content (0–20 mol%) and heating temperature (500–800°C), the effects of various processing parameters on the films characteristics are studied. With the increase of La content, the relative dielectric constant (ε
r) of PLT thin film increases from 53 up to 101 with a maximum existing at the heating temperature of 700°C. It was found that the dielectric loss factor (tan
δ), coercive field (E
c) and remanent polarization (P
r) decreased, but pyroelectric coefficient (γ) increased with the increase of La content. The PLT thin film exhibits a lower current density and a larger pyroelectric coefficient at heating temperature of 700°C and La content of 20 mol%.
A Novel Thin Gate-Oxide-Thickness Measurement Method by LDD (Lightly-Doped-Drain)- NMOS (N-Channel Metal-Oxide-Semiconductor) Transistors
Authors: Shih Jiaw-Ren , Lee Jian-Hsing , Liew B. K. , Hwang Huey-Liang
Published: October 2002

In this paper, we propose a novel thin gate-oxide-thickness measurement method by using Lightly-Doped-Drain (LDD) N-Channel Metal-Oxide-Semiconductor (NMOS) snapback characteristics. For device with thin oxide 150 Å∼60 Å and optimized LDD doping profile, the drain breakdown voltage will be oxide-thickness limited, and therefore the oxide breakdown's critical-field is about 10 MV/cm. By this characteristic, as high-voltage sine-waveform generator provides the necessary voltage to lead to the grounded-gate LDD-NMOS happening gate-assisted drain breakdown and drives its parasitic n-p-n bipolar turn-on. The voltage-waveform collapses immediately as the applied-voltage exceeds the critical oxide-field 10 MV/cm. Therefore, the oxide thickness can be determined.
Observation of Spatial and Temporal Evolution of Planar Photoinduced Waveguide in LiNbO3 Crystal
Authors: Shiratori Akira , Aida Ryuji , Hagari Ryohei , Obara Minoru
Published: October 2002

We have two-dimensionally visualized a photoinduced planar waveguide produced in a
photorefractive LiNbO3 crystal. Temporal and spatial evolution of the waveguide was investigated
by the interferometric imaging technique. The guiding of a probe He–Ne laser in the waveguide was
also experimentally observed.
Epitaxial Growth of ZnSe on Si(111) with Lattice-Matched Layered InSe Buffer Layers
Authors: Löher Thomas , Koma Atsushi
Published: October 2002

The growth of thick ZnSe films with high crystalline quality on a Si substrate is impaired by the 4.4% lattice mismatch at the interface. Based on the concept of van der Waals epitaxy, an InSe buffer layer was inserted between ZnSe and Si.
The three-monolayer-thick buffer layer was grown by molecular beam epitaxy on a hydrogen-terminated Si(111) substrate. Despite a lattice mismatch of 4.2%, the InSe film grew with high crystalline quality and without lattice distortions. ZnSe was
subsequently grown on the InSe layer. The lattice mismatch of 0.2% at this interface appeared to be favorable for the growth of high-quality ZnSe films. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy studies in the thin-film growth regime are presented.
Conversion of Nickel Coated Carbon Nanotubes to Diamond under High Pressure and High Temperature
Authors: Han Weiqiang , Fan Shoushan , Li Qunqing , Zhang Chuan Lin
Published: October 2002

Nickel coated carbon nanotubes have been converted to diamonds with high
conversion ratio at 8 GPa and 1600°C. Nickel coated on the surface of each and every
carbon nanotube might act as catalyst and play the key role for high conversion ratio
of carbon nanotubes to diamond. Pure carbon nanotubes can only be converted to high
oriented graphite under same high pressure and high temperature condition.
Heat Treatment of Amorphous and Polycrystalline Silicon Thin Films with H2O Vapor
Authors: Toshiyuki Sameshima Toshiyuki Sameshima , Mitsuru Satoh Mitsuru Satoh , Keiji Sakamoto Keiji Sakamoto , Ai Hisamatsu Ai Hisamatsu , Kentaro Ozaki Kentaro Ozaki , Keiko Saitoh Keiko Saitoh
Published: October 2002

Changes in electrical and optical properties induced by heat treatment with H2O vapor at 350 °C are reported for laser-induced amorphous silicon, low pressure chemical vapor amorphous silicon (LPCVD a-Si) and laser crystallized polycrystalline silicon films. The dark conductivity was reduced and the photoconductivity was increased by the heat treatment for these films. The optical absorption in the photon energy range lower than 1.5 eV was reduced for the a-Si films. The optical band gap was slightly increased from 1.48 eV to 1.51 eV for the LPCVD a-Si. The increase in hydrogen concentration was less than 2×1020 cm-3 after the treatment. These results show that the heat treatment with H2O vapor reduces the defect density in the silicon films with a small amount of hydrogen incorporation.
Highly Stable ZnO Thin Films by Atomic Layer Deposition
Authors: andMakoto Konagai Baosheng Sang
Published: October 2002

B-doped ZnO films were prepared on Corning 7059 glass by atomic
layer deposition (ALD) using diethylzinc (DEZn) and H2O as reactant gases,
and diborane (B2H6) as the dopant gas. The stability of the
electrical properties of the obtained ZnO
films was investigated. Variations in the electrical properties of
the ZnO films with air exposure and heat treatment were observed.
The stability of the electrical properties of the ZnO films grown by
metalorganic vapor deposition (MOCVD) and photo-MOCVD was also
investigated. It was found that the electrical properties of ZnO
films grown by ALD were very stable, indicating that the ALD technique
is attractive for the deposition of high-quality transparent conducting ZnO films.
High-Quality B-Doped Homoepitaxial Diamond Films using Trimethylboron
Authors: Yamanaka Sadanori , Watanabe Hideyuki , Masai Shigeo , Takeuchi Daisuke , Okushi Hideyo , Kajimura Koji
Published: October 2002

High-quality B-doped homoepitaxial diamond films have been
synthesized by microwave plasma chemical-vapor-deposition (CVD) using a
mixture consisting of CH4, H2, and trimethylboron B(CH3)3 diluted by H2 gas.
These films have been obtained on the basis of the approach that high-quality
diamond films should be grown in a clean CVD system. Hall-effect
measurements of the film show that the Hall mobility exceeds about 1800 cm2/V·s when the hole concentration is 2.3×1014 cm-3 at room temperature (290 K) and about 3300 cm2/V·s at 170 K. These results indicate that the quality of
the present B-doped CVD films is comparable with or better than that of high-quality natural diamonds.
15 T Cryocooled Nb3Sn Superconducting Magnet with a 52 mm Room Temperature Bore
Authors: Watanabe Kazuo , Awaji Satoshi , Motokawa Mitsuhiro , Mikami Yukio , Sakuraba Junji , Watazawa Keiichi
Published: October 2002

We succeeded in demonstrating a 15.1 T cryocooled Nb3Sn superconducting magnet with a 52 mm
room temperature bore. Two operating currents of 157 A and 90 A for the divided section coils were
utilized for the first time in a cryocooled superconducting magnet system. It is found that the current
leads are no longer the dominant heat loads because of the use of high-temperature superconductors. In
order to realize a high-field cryocooled superconducting magnet comparable to the usual superconducting
magnet immersed in liquid helium at 4.2 K, we maintained the coil temperature at a value below 5.0 K
during the field sweep in a high magnetic field region.
Free Electron Laser Oscillation down to the Deep UV Range Using a Small-Scale Storage Ring
Authors: Yamada Kawakatsu , Sei Norihiro , Yamazaki Tetsuo , Ohgaki Hideaki , Mikado Tomohisa , Sugiyama Suguru , Kawai Masayuki , Yokoyama Minoru
Published: October 2002

A free electron laser (FEL) based on the small-scale storage-ring NIJI-IV at the
Electrotechnical Laboratory (ETL) was operated at wavelengths down to the deep
ultraviolet (UV) range. The laser oscillation was obtained at regions from 315 to
287 nm and from 253 to 228 nm using low-loss dielectric multilayer mirrors optimized at
300 and 240 nm, respectively, for the laser cavity. The wavelength of 228 nm is
shorter than the former record for FELs by more than 10 nm. Suppression of the beam
instability led to a drastic enhancement of the laser gain which enabled us to achieve the
FEL oscillation at such short wavelengths even in a small-scale storage ring.