bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Etching Gases and Bias Frequency on Notching and Charging in High-Density Plasma
Authors: Tabara Suguru
Published: October 2002

Effects of etching gas chemistry and bias frequency on notching and electron shading
damage in metal etching were investigated by using high-density plasma etching tools. It was
found that employing HCl-containing plasma in the overetching process and/or lowering the
bias frequency could reduce notching and electron shading damage. The results of optical
emission spectroscopy and the electron shading damage evaluation suggest that low-energy H+ ions play an important role. The ion energy distribution function is bimodal at low bias
frequency or high plasma density, and the minimum ion energy decreases as both the bias
frequency and the ion mass decrease. Therefore, the decrease in the ion energy at the
electrode contributes to the reduction of electron shading damage and notching. The
neutralization of the negatively charged photoresist sidewalls by low-energy light ions is
considered to be the reason for the reduction in electron shading
damage and notching.
Gamma Dosimetry with CR-39 Etch Track Detector
Authors: Dogar Matiullah , Ahmad Nasir , Amin Masood , Kudo Katsuhisa
Published: October 2002

To preserve and improve the safety of food for commercial purposes, it is exposed to high
gamma-ray doses. The gamma-ray doses used for this purpose range from 0.15 kGy to 50 kGy.
At such high doses, the etching characteristics of CR-39 are severely affected. This property,
therefore, can be used to develop a CR-39-based gamma dosimeter. In this context, systematic
studies were carried out and the bulk etching rate was determined as a function of gamma-ray
dose using different methods.
Diamagnetic Force Acting on Electron Beams in Superconducting Tubes
Authors: Kazuo Sakai Kazuo Sakai , Yoshihiro Nakamura Yoshihiro Nakamura
Published: October 2002

In this paper, the diamagnetic force, due to the Meissner effect, acting on the electron beam of finite radius which runs through the superconducting tube, is calculated. The effects of the diamagnetic force are theoretically studied. The diamagnetic force guides the electron beam toward the tube axis and conforms the shape of the cross section of the beam. However, it does not yield the focusing of a single beam of finite radius.
A New Method for the Precise Measurement of Wafer Roll off of Silicon Polished Wafer
Authors: Kimura Masahiro , Saito Yasuo , Daio Hiroshi , Yakushiji Kenji
Published: October 2002

A new method using a stylus profiler and a block gauge has been developed
to measure the precise profile of wafer roll off occurred within the edge exclusion
length. The results from the new method have a good agreement of those using the
conventional capacitive gauging tool, when the height deviation of wafer roll off is
measured. The new method can specify the exact lateral position with respect to the
physical edge of wafer.
Magnetic-Field-Induced Transitions of Many-Electron States in Quantum Dots
Authors: Natori Akiko , Nakamura Daisuke
Published: October 2002

The many-electron eigenstates
of anisotropic parabolic quantum
dots with cylindrical symmetry are investigated
using an
unrestricted Hartree-Fock method,
in a magnetic
field parallel to the cylindrical z-axis.
The many-electron eigenstates are assigned by two quantum
numbers,
L
z
and S
z, the z-components of the total orbital angular momentum and the
total spin, respectively.
The many-electron ground states
exhibit sequential transitions
via three stages with increasing magnetic field.
At the transition magnetic fields,
the ground state energy crosses that of the
first-excited state with different values of (L
z, S
z)
and they replace each other.
The phase diagram of the
ground state is obtained in a space of the magnetic field and the
electron number.
The phase diagram is greatly affected by the lateral
extent of quantum dots, but the
effect of the vertical extent
is small for quasi-two-dimensional
quantum dots.
In these magnetic field induced transitions, the
Hartree interaction
plays a dominant role.
Variation of Electronic States in Mesoscopic Scale Structures of TiO2(110) Surface Observed by Scanning Tunneling Microscopy/Spectroscopy
Authors: Sakai Yoshiyuki , Ehara Shaw
Published: October 2002

Variation in the electronic energy spectrum of gap states on a
TiO2(110) surface with mesoscopic scale structures was observed
by scanning tunneling microscopy and spectroscopy. Islands of
100–200 Å in size were formed on a (110) surface of a single
crystal of TiO2 by bombardment with argon ions and an
annealing at 420°C in an ultrahigh vacuum. In the
tunneling spectrum at the island surface site, a hump of unoccupied
gap states was observed besides peaks of the valence band and
conduction band. On the other hand, at the hollow site between
islands, the energy of this peak gradually shifted down below the
Fermi level. The energy shift of this gap state is explained by the
difference in the Madelung potentials at a hollow site and an island
surface site.
Electronic Structure of the Si(100) Surface A Defects Analyzed by Scanning Tunneling Spectroscopy at 80 K
Authors: Sainoo Yasuyuki , Kimura Tomohiko , Morita Ryuji , Yamashita Mikio , Hata Kenji , Shigekawa Hidemi
Published: October 2002

The A defects on the Si(100) surface can be classified as
A1, A2, and A3 at low temperatures. We carried out
scanning tunneling microscopy observations and scanning tunneling
spectroscopy measurements at ∼80 K to study their electronic
structures. We found that the A1 defect is semiconductive similar
to the A defect at room temperature (RT), while the A2 and
A3 defects exhibited states in the surface band gap at 80 K. On
comparing these results with the theoretical models, we concluded that
the A1 defect correspond to the Rebonded vacancy model. The
broken vacancy model and the twisted vacancy models are the possible
candidates for the A2 and A3 defects,
respectively.
Spin-Dependent Surface Characteristics of an Absorbed Hydrogen Atom under a Scanning Tunneling Microscope Environment–Atom Manipulation by Magnetic Field
Authors: Sawamura Makoto , KoichiMukasa KoichiMukasa
Published: October 2002

We investigate the electronic states of a scanning tunneling microscope environment using first principles molecular orbital calculations, explicitly including
spin states. We employ a cluster model comprised of a silicon surface and an absorbed
hydrogen atom under a gold probe tip. We find that spin multiplicity of the system
drastically changes the potential energy surfaces of the absorbed atom between the
surface and the probe. Under the gold probe tip, it is observed that the desorption
energy for a hydrogen atom from the silicon surface decreases from 4.09 eV to 2.84 eV
when an external electric field, biased sample-negative, is applied along the cluster axis
with the value of 0.3 V/Å at the singlet spin state. At the triplet spin state, however,
the barrier of the potential well completely disappears under the electric field, sample-negative bias, with the value of 0.1 V/Å, which induces atom transfer from the surface
to the probe. We assume that the tip-sample distance is 6.0 Å.
Vibrational-Energy Redistribution in Single-Atom Manipulation by Scanning Tunneling Microscope
Authors: Shi Qiang , Huang Dehuan , Zhu Qingshi
Published: October 2002

A pairwise phenomenon is observed when we attempt to extract a
single H atom from a monohydride Si(100)-2×1:H surface. This is attributed to the final vibrational excitation induced by the tunneling electrons and the desorption of two H atoms on one Si dimer simultaneously as an H2 molecule. The pair effect is thought to be direct evidence of vibrational-energy transfer on the surface.
How Much Chemistry is There in Chemical Force Microscopy?
Authors: McKendry Rachel , Theoclitou Maria-Elena , Abell Chris , Rayment Trevor
Published: October 2002

Chemical force microscopy (CFM) is a name given to the technique whereby chemical specificity is added
to atomic force microscopy by deliberate derivatisation of an atomic
force microscopy (AFM) probe. The most fundamental
question that surrounds the technique is-how much `chemistry' is added. Put another way, how
valid is it to interpret image and adhesion contrast in terms of differences in surface chemistry? In
this paper three aspects of this problem are described. In the first, the role of the substrate is
discussed. Secondly, a series of experiments concerned with the interactions of π electron systems is
described. These show that it is not possible to interpret CFM solely in terms of electronic, or
intermolecular interactions. The third section reviews CFM experiments with chiral surfaces. It is
shown that chiral discrimination is not only possible but that the results are in accordance with
parallel experiments using high performance liquid chromatography (HPLC). Somewhat
surprisingly, CFM experiments are more sensitive to chirality than
HPLC.
Atomic Force Microscopic Observation of Three-Dimensional Morphological Changes of Neurons When Stimulated by a Neurotransmitter
Authors: Tomoko Hosono Tomoko Hosono , Mari Yamanaka Mari Yamanaka , Takuro Tojima Takuro Tojima , Yukako Yamane Yukako Yamane , Hisayo Sadamoto Hisayo Sadamoto , Dai Hatakeyama Dai Hatakeyama , Hisashi Haga Hisashi Haga , Kazushige Kawabata Kazushige Kawabata , Kazuhiro Abe Kazuhiro Abe , Etsuro Ito Etsuro Ito
Published: October 2002

As the first step in the study of morphological changes in neurons associated with their functional changes, we applied atomic force microscopy (AFM) for the observation of fine three-dimensional morphological changes in rat cerebellar granule cells stimulated by an agonist of glutamate receptors, N-methyl-D-aspartate (NMDA). The AFM revealed that NMDA changed the cross-sections of cell bodies from a trapezoid-like form to a triangle-like form within a minute. The fine hill-like structures on the top surfaces of the cell bodies became wider during the same period. These results were suggested to be induced by the depolymerization of filamentous actin triggered by the entry of Ca2+ via cation channels complexed with the activated NMDA receptors.
Atomic Force Microscopy Cantilevers for Sensitive Lateral Force Detection
Authors: Kageshima Masami , Ogiso Hisato , Nakano Shizuka , Lantz Mark A. , Tokumoto Hiroshi
Published: October 2002

In order to enhance the lateral force sensitivity of atomic force microscopy (AFM) to detect
atomic or molecular scale interaction, two types of force sensors were fabricated by additional
processing of commercial sensors with the help of focused ion beam (FIB) technology. In one
type of cantilever, a hinge was fabricated in the middle of the commercial cantilever by FIB
milling, resulting in the reduction of the lateral force constant from 1204 N/m to 118 N/m. For
further enhancement of the lateral sensitivity without causing snap-in behavior, a novel force
sensor was designed and fabricated through a combination of FIB milling and FIB deposition
techniques. The lateral force constant was reduced, for example, from 3600 N/m to 20 N/m,
and the measured lateral force resolution attained the order of
1 nN.
Calculation of Electrical Properties of Novel Double-Barrier Metal Oxide Semiconductor Transistors
Authors: Shibahara Tsuyoshi Hatano , Yokoyama Shin
Published: October 2002

We propose novel ultrasmall metal-oxide-semiconductor (MOS) transistors with double-potential barriers.
The structure is similar to the lightly doped drain (LDD) MOS transistors
with upper and lower gates.
The double-potential barriers, which are controlled by the upper gate
voltage, are formed under the side wall spacers.
It is confirmed by simulation that the tunneling
current through the double-potential barriers is larger than the thermally
excited current at 77 K.
Then, the Coulomb blockade effects, i.e.,
the suppression of the tunneling current in the
vicinity of the zero drain voltage and the Coulomb oscillation, are
observable at 77 K.
Thermally Induced Changes in the Hydrogen Microstructure of Amorphous Hydrogenated Silicon Films, Analyzed Using In Situ Real Time Infrared Spectroscopy
Authors: Keudell A. von , Abelson J. R.
Published: October 2002

Changes in the hydrogen content and bonding in amorphous hydrogenated silicon (a-Si:H) films
during stepwise thermal annealing are measured using in situ real time infrared spectroscopy. The
experimental spectra are fit using previously identified SiH stretching modes for hydrogen bonded
at isolated network sites, hydrogen in platelet-like configurations and hydrogen at surfaces.
Based on this mode separation, the release of hydrogen from surfaces and platelet configurations
is found to occur at ∼320–370°C. By 470°C, these groups are completely released from the
sample, whereas isolated SiH network sites are still present. This thermal annealing of the sample
also irreversibly changes the microstructure and thereby the distribution of available hydrogen
bonding sites in the amorphous network. Re-hydrogenation experiments show that isolated
bonding sites are created and platelet and surface bonding sites are removed from the hydrogen
density of states. This structural transformation during annealing is interpreted as the release of
hydrogen from platelet like configurations and the reformation of Si–Si bonds in a-Si:H.
Aggregation Effect on the Third-Order Optical Nonlinearity in 4-(N,N-Diethylamino)-β-Nitrostyrene-Doped Polymer Films
Authors: Hidetoshi Murakami Hidetoshi Murakami , Ryuji Morita Ryuji Morita , Mikio Yamashita Mikio Yamashita , Hidemi Shigekawa Hidemi Shigekawa
Published: October 2002

The absorption and electroabsorption (EA) spectra for 4-(N,N-diethylamino)-β-nitrostyrene (DEANST)-doped poly(methyl methacrylate) (PMMA) films in the dopant concentration range of 0.1–40 wt% were measured.
Dispersion of the third-order nonlinear optical susceptibility χ(3)(-ω; 0,0,ω) at each concentration was determined. In addition, the static polarizability change Δα and the static dipole-moment change Δµ were evaluated.
Furthermore, the picosecond emission-decay profiles and the time-resolved emission spectra for 0.1–40 wt% DEANST-doped PMMA films were measured.
From the experimental results, it was concluded that DEANST molecules in PMMA films aggregate at concentrations over 5 wt%.
This aggregation gives rise to two new absorption bands.
The intermolecular interaction affected by aggregation causes a decrease in Δµ, in the average effective third-order molecular hyperpolarizability <γ(-ω;0,0,ω) > eff, and in the nonproportional behavior in |χ(3)(-ω;0,0,ω)| with increasing dopant concentration.
Furthermore, this aggregation explains the absorption spectral change, the EA spectral shift and the existence of two emission-decay constants with concentration.
Finally, the average aggregation number of DEANST molecules was evaluated to be two, which suggests that DEANST molecules in the PMMA film form a dimer at concentrations over 5 wt%.
Implementation of Single-Electron Transistor with Resistive Gate
Authors: Pashkin Yuri , Nakamura Yasunobu , Tsai Jaw-Shen
Published: October 2002

We have fabricated and measured a resistively coupled single electron transistor (R-SET). In our
implementation, a chromium thin-film resistive gate was connected directly to a mesoscopic island formed
between two ultrasmall Al/AlO
x
/Al tunnel junctions. The transistor was fabricated by electron beam
lithography using the suspended bridge technique. We have measured the current-voltage-gate voltage
dependences of the R-SET and observed a characteristic Coulomb blockade pattern. Our simulations based
on the orthodox theory of single electron tunneling show good qualitative agreement with the experimental
data.
Bound-free Vacuum UV Emissions of Kr+Li and Xe+Li Ionic Excimers by Relativistic e-Beam Pumping
Authors: Xing Da , Wang Qi , Ueda Ken-ichi
Published: October 2002

The vacuum UV fluorescences from rare-gas-alkali ionic excimer
Kr+Li were observed by the relativistic electron beam excitation
of a gas mixture of krypton with a hot vapor of lithium. The observed
two diffuse emission bands centered at 147 and 149 nm were assigned
to the 21Σ+→11Σ+ and
11Π→11Σ+ transitions of the Kr+Li
ionic excimer. A maximum net gain coefficient about 0.05 cm-1
for the 147-nm band was obtained in the present experiment. Another
two similar diffuse bands observed at 186 and 189 nm from Xe/Li gas
mixtures were assigned to the same transitions of the Xe+Li ionic
excimer molecule.
Magneto-Optical Properties of Cerium-Substituted Yttrium Iron Garnet Single Crystals Grown by Traveling Solvent Floating Zone Method
Authors: Higuchi Sadao , Takekawa YasunoriFurukawa , Kitamura OsamuKamada
Published: October 2002

A cerium-substituted yttrium iron garnet (Y3-x
Ce
x
Fe5O12) single
crystal was grown by the traveling solvent floating zone (TSFZ) method
in an oxygen environment. Using a Fe- and Ce-rich solvent, high
quality single crystals with smooth and lustrous surface were grown at
a rate of 1.0 mm/h. The segregation coefficient of Ce was calculated
approximately as 0.2 from the compositional profile in the grown
crystals measured by electron probe X-ray microanalyzer (EPMA). The
optical absorption coefficient and the Faraday rotation angle of
Y2.82Ce0.18Fe5O12 at 1550 nm wavelength were
0.12 cm-1 and -740 deg/cm, respectively. The figure of merit
of a Faraday rotator was 1423 deg/dB. The absorption loss and
sensitivity of the same Y2.82Ce0.18Fe5O12 (d=0.6 mm) for the magnetic field sensor were 0.03 dB and 0.1%/Oe, respectively, at 1550 nm wavelength. These results
suggest that cerium-substituted yttrium iron garnet is a high
performance material for the Faraday rotator at 1550 nm wavelength.
Equivalent Circuit Model for Thresholdless Antiferroelectric Liquid Crystal Displays
Authors: Yamaguchi Takeshi , Hara Yujiro , Fujiwara Hisao , Itoh Goh , Okumura Haruhiko
Published: October 2002

For high quality displays, analog responding liquid crystals with spontaneous polarization
need to be coupled with active matrix driving schemes. Our goal is to investigate the
possibilities for optimizing liquid crystal materials, thin film transistors, and driving schemes.
In this paper, the electrooptical properties of thresholdless antiferroelectric (TLAF) liquid
crystal displays (LCDs), which are analog responding, are modeled using an electric circuit
which can be applied to conventional simulators. A novel procedure for deducing the circuit
parameters on the basis of the experimental results is discussed. It was found that the voltage-dependent capacitance due to the induced spontaneous polarization is important for describing
the static and dynamic behavior at different applied voltages. It is shown that our equivalent
circuit model reproduces the pixel voltage as well as the transmittance of active-addressed
TLAF-LCDs.
Crystallite Size Dependence of Plasmon Energies in Polycrystalline Graphite Observed by Reflected Electron Energy Loss Spectroscopy
Authors: Hashimoto Hiroyuki , Nishiuma Satoru , Takada Kazuhiro , Nakamura Kumi , Ueno Rie , Den Tohru
Published: October 2002

Both the energy losses of π electron plasmon and valence electron plasmon in
polycrystalline graphite have been measured by reflected electron energy loss spectroscopy
(REELS). It was found that when crystallites are smaller than 10 nm, the π plasmon
energy is lower than the value estimated from the valence plasmon energy which directly
reflects the density. Moreover, there is a correlation between the π plasmon energy and
the relative intensity of the π plasmon peak to the elastic peak. Thus, the decrease of
the π plasmon energy was explained by a crystallite size effect such as a decrease in π
electron density. This REELS technique was applied to estimate the chemical state in
carbon films obtained by thermal chemical vapor deposition (CVD). The two-dimensional
distribution of the graphitic carbon was successfully measured at a
spatial resolution of less than 1 µm.
GaAs Single Electron Transistors Fabricated by Selective Area Metalorganic Vapor Phase Epitaxy and Their Application to Single Electron Logic Circuits
Authors: Nakajima Fumito , Kumakura Kazuhide , Motohisa Junichi , TakasiFukui TakasiFukui
Published: October 2002

GaAs single electron transistors (SETs) are successfully fabricated using selectively
grown GaAs/AlGaAs modulation doped structures by metalorganic vapor phase epitaxy
(MOVPE) on (001) GaAs masked substrates. SET shows clear Coulomb oscillations and
Coulomb gaps modulated by gate voltage. GaAs single electron tunneling inverter circuits
having a SET and a variable load resistance are also formed. The operation of a resistance-load inverter circuit is confirmed at 1.9 K from the transport properties of this SET and input-output characteristics.
Scattering Characteristics of Layered Chiral Media for Normally Incident Transverse Waves
Authors: Ro Ruyen , Sung Chia-Chi , Nai-HsiangSun Nai-HsiangSun
Published: October 2002

Reflection and transmission characteristics of layered chiral media bounded by either chiral or
achiral media for normally incident transverse waves are investigated. The elastic field behavior in
a chiral medium is readily described using governing equations and constitutive relations for
noncentrosymmetric, isotropic micropolar materials. Using appropriate field representations along
with prescribed boundary conditions, scattering characteristics at chiral-chiral and achiral-chiral
interfaces are readily determined. To further investigate scattering characteristics of layered chiral
media, a matrix-propagating method is employed in this study to determine the scattering matrix.
Scattering characteristics of the four-layer chiral media bounded by two semi-infinite achiral media
are simulated and verified. The effects of wave parameters on reflection and transmission
coefficients are also discussed.
(012) Preferred Orientation of LiNbO3 Thin Films by RF-Magnetron Sputtering
Authors: Park Sung-Kun , Baek Min-Soo , Kim Seoung-ChoonBae , Kwun Sung-Yul , Kim Young-Jin , Kim Jee-Hyun
Published: October 2002

LiNbO3 films were prepared by an rf-magnetron sputtering
technique using a sintered LiNbO3 target containing
potassium. The addition of potassium to the target enhances the
mobility of the sputtered materials, through the re-evaporation of the
potassium on the surface of the substrate during crystallization of
the growth of the LiNbO3. The enhanced mobility enables the
growth of a LiNbO3 film with a minimum surface energy structure
without effect from the underlying layer. The rf power, working
pressure, and substrate temperature were selected as process variables
to investigate any changes in the preferred orientation of
LiNbO3. (012) preferred oriented films were fabricated within a
deposition rate range from 25 Å/min to 50 Å/min. (012)
preferred orientation of LiNbO3 film is due to the minimum
surface energy of (012) plane.
Prediction of Surface Normal Velocity for an Arbitrary Acoustic Source Using an Equivalent Phased Array Method
Authors: Tomoki Yokoyama Tomoki Yokoyama , Tetsuro Teshima Tetsuro Teshima , Akio Hasegawa Akio Hasegawa
Published: October 2002

The equivalent phased array method (EPAM) treats an acoustic source as a “phased array” composed of many small elements, in order to predict acoustic fields generated by the source. In this paper, a new method of EPAM, based on solutions to the exterior steady-state acoustic radiation problem, is proposed. We attempt to apply this method, instead of near-field acoustical holography (NAH), to predict the surface normal velocity of the acoustic source. This method is applicable to the prediction of the surface normal velocity for sources that have arbitrary shapes and is therefore expected to work well for the practical experiments. The results of computer simulations using quadrapole-type sources demonstrate the validity of this method.
Effects of Interface Traps on Charge Retention Characteristics in Silicon-Quantum-Dot-Based Metal-Oxide-Semiconductor Diodes
Authors: Shi Yi , Saito Kenichi , Ishikuro Hiroki , Hiramoto Toshiro
Published: October 2002

We have demonstrated the effects of interface traps and defects on the charge retention characteristics in silicon-quantum-dot (Si-QDs)-based metal-oxide-semiconductor (MOS) memory structures. MOS diodes with various interface traps and defects introduced by thermal annealing treatment are investigated using a capacitance-voltage (C-V) measurement technique. The model of deep trapping centers including three-dimensional quantum confinement and Coulomb charge effects has been developed to successfully explain the observed long-term charge retention behaviors.
Ultrasonic Butt Welding of Aluminum and Stainless Steel Specimens Using a 15 kHz Welding System
Authors: Tsujino Jiromaru , Ueoka Tetsugi , Kashino Takashi , Sugahara Fumiharu
Published: October 2002

The welding characteristics of aluminum and stainless steel plate specimens of 6 mm thickness
joined by a 15 kHz ultrasonic butt welding system are studied. Both materials are anticorrosive
and have various applications due to small deformation at the welded part. The specimens without
special surface treatment were joined end to end with the weld strength of 100 MPa. The
hardness of aluminum decreases at the area close to the welded surface, which is the same as in
other materials. The hardness of stainless steel increases by approximately 20% near the welded
surface. The increase in hardness due to ultrasonic vibration was observed for the first time
though only the decrease in hardness was mentioned in previous studies.
Magnetic Neutral Loop Discharge (NLD) Plasma and Application to SiO2 Etching Process
Authors: Chen Wei , Hayashi Toshio , Itoh Masahiro , Morikawa Yasuhiro , Sugita Kippei , Shindo Haruo , Uchida Taijiro
Published: October 2002

The applicability of the magnetic neutral loop discharge (NLD) plasma etching apparatus to the 0.1 µm wafer process was experimentally verified. Variation of the
SiO2 etch rate was obtained to within 1.3% (2% as 3σ value) on a 200 mm wafer, by
applying a functional current to the magnetic coil with 0.1 Hz. A superfine trench
pattern with a width of 20–50 nm and a depth of 800 nm was also successfully
fabricated with an electron beam resist mask in a C4F8 + CH2F2 plasma at
0.3 Pa.
Test-Wave Measurements of Microwave Absorption Efficiencyin a Planar Surface-Wave Plasma Reactor
Authors: Ivan Ghanashev Ivan Ghanashev , Shin Morita Shin Morita , Naoki \scToyoda Naoki \scToyoda , Masaaki Nagatsu Masaaki Nagatsu , Hideo Sugai Hideo Sugai
Published: October 2002

A major obstacle for experimental surface-wave (SW) excitation
and propagation studies in SW plasma is the self-consistent
behaviour of the latter, which does not permit continuous
variation of the electron density n
e. In the present
study, we demonstrate how this obstacle can be overcome by an
independent plasma source, in our case, an inductively coupled
plasma (ICP) created by a high-power RF (13.56 MHz) generator.
Through a rectangular waveguide short-circuited at its end by a
movable plunger, we introduced into the ICP a weak (power
less than 20 W) nonionising 2.4 GHz microwave.
This permitted us to highlight important SW excitation and
propagation phenomena. In particular, we confirmed the existence
of the predicted [Jpn. J. Appl. Phys. 36 (1997) 4704]
resonance minima in the n
e dependence of the power
reflection coefficient. The influence of the plunger position
on the chamber matching was studied systematically and four
different coupling aperture geometries were compared.
Single Electron Transfer Logic Gate Family
Authors: Yoshikawa Nobuyuki , Fukuzato Chikashi , Sugahara Masanori
Published: October 2002

Single electron transfer logic circuits, where logical bit information is represented by the existence of discrete small current pulses accompanied by single electron tunneling (SET) in a one-dimensional array of small tunnel junctions, have been investigated. The basic operation characteristics of several key circuit elements, such as an SET transmission line, a confluence circuit, a split circuit and a set-reset gate were examined and their correct functionality was verified by Monte Carlo simulation. We have shown that basic logic gates, such as NOT, AND and OR, can be implemented using these circuit elements if we provide periodic single electron clock pulses to the gates. Robustness of these logic gates has also been investigated by calculating the dc bias margin.
Effect of Electromagnetic Waves Propagating in the Periphery of Electron Cyclotron Resonance Plasma on the Uniformity
Authors: Yoko Ueda Yoko Ueda , Hiroshi Muta Hiroshi Muta , Yoshinobu Kawai Yoshinobu Kawai
Published: October 2002

Stable vacuum regions in the periphery of an electron cyclotron resonance (ECR) plasma near a quartz window were found to possibly contribute to plasma uniformity as a kind of a waveguide for incident electromagnetic waves. Mode conversion of electromagnetic waves with long wavelength into the right circularly polarized wave was observed clearly at a certain radial position. In order to investigate the effects of electromagnetic waves propagating in the vacuum region on plasma production or uniformity, microwave propagation in a partially filled plasma chamber was examined numerically. The numerical results indicated that the electromagnetic waves with long wavelengths in the periphery of the plasma were converted into extraordinary or electrostatic waves outside the ECR region and that power absorption took place locally. Furthermore, it was found to be strongly dependent on the width and shape of the vacuum region and gas pressure. Physical considerations of these results revealed the reason why plasma uniformity is influenced by a magnetic field gradient.
Extended Anode Effect in Coaxial Magnetron Pulsed Plasmas for Coating the Inside Surface of Narrow Tubes
Authors: Seiki Sugimoto Seiki Sugimoto , Yuki Uchikawa Yuki Uchikawa , Kiyoshi Kuwahara Kiyoshi Kuwahara , Hiroshi Fujiyama Hiroshi Fujiyama , Hajime Kuwahara Hajime Kuwahara
Published: October 2002

In order to coat functional thin films onto the inside surface of
narrow tubes, a coaxial magnetron pulsed plasma (CMPP) device has
been developed. The feature of this device is that deposited
conductive films play the role of an anode. Consequently, plasmas
are generated away from the anode located at one end of the tube and
the distribution of film thickness widens with increasing deposition
time. This is called the extended anode effect. The shifting
velocity of the main position for plasma generation was dependent on
the properties of the target materials. The shifting velocity increased
with sputtering yield and decreased with the electrical resistivity
of target materials.
The Energies of Positive and Negative Ions in an RF Plasma in Nitrous Oxide
Authors: Rees J. Alan , Greenwood Claire L. , Seymour David L.
Published: October 2002

It is known that negative ions are important in the plasma oxidation of silicon and silicon nitride
surfaces and there is interest in the use of nitrous oxide instead of oxygen as the plasma gas. The
present paper describes an investigation into the distribution of energies with which the O- ions
produced in a capacitive rf plasma impinge on the grounded discharge electrode and compares these
energies with those of the positive N2O+ ions produced under the same plasma conditions. It is
shown that the maximum energy of the O- ions is largely determined by the d.c. bias of the driven
electrode and is independent of changes in the plasma potential. It is, therefore, possible in such
systems to select, independently, the energies of the positive and negative ions. The energy
distribution of the O- ions shows interesting structure, which for a given d.c. bias, is a function of the
input rf signal. The investigation confirms that, for strongly asymmetric geometries, negative ions
produced in the sheath at the driven electrode of a capacitive rf plasma system travel through the
plasma and impact on the counter electrode with a range of energies.
Hybrid Modeling of a Capacitively Coupled Radio Frequency Glow Discharge in Argon: Combined Monte Carlo and Fluid Model
Authors: Bogaerts Annemie , Gijbels Renaat , WimGoedheer WimGoedheer
Published: October 2002

A hybrid model has been developed for a capacitively coupled rf glow discharge in argon, employed as a spectroscopic source in the field of analytical chemistry. The cell is a rather small cylinder with a very small rf-powered electrode (only 5 mm in diameter). The typical working conditions applied for analytical spectroscopy are a gas pressure of 6 Torr and incoming power of 10 W. The hybrid model consists of a Monte Carlo model for the electrons and a fluid model for the electrons and argon ions. The latter model also contains Poisson's equation, to obtain a self-consistent electric-field distribution. The input values for the model are the gas pressure, the discharge power, the cell geometry and the collision cross sections. The typical calculated results include the rf and dc bias voltage, the electrical current at the rf electrode, the potential distribution, the density of argon ions and electrons, the electron energy-distribution function and information about the collision processes of the electrons. These results are presented throughout the discharge cell and as a function of time in the rf cycle. Moreover, we have investigated how many rf cycles have to be followed with the Monte Carlo model before a periodic steady state is reached.
Two-Dimensional Modeling of Spatiotemporal Structure of Inductively Coupled Plasma
Authors: Kazuhiro Kamimura Kazuhiro Kamimura , Katumi Iyanagi Katumi Iyanagi , Nobuhiko Nakano Nobuhiko Nakano , Toshiaki Makabe Toshiaki Makabe
Published: October 2002

An inductively coupled plasma (ICP) is one of the candidates for
a high density, large area and uniform plasma source for use in plasma
processing even under low pressure conditions. We have developed a
two-dimensional and time dependent model for a collision dominated ICP,
taking into consideration electron transport in both the electric and
magnetic fields, based on the relaxation continuum (RCT) model in a
self-consistent manner. The 2D-space and time structure of an ICP,
driven by a frequency of 13.56 MHz and a current amplitude of 10 A at
0.3 Torr in Ar is mainly discussed. In particular, a space potential
with a double frequency time variation, at a plasma density of
1011 cm-3 is clarified as well as a potential distribution of the
insulating wall of ICP. The importance of the power deposition by
E

r
×B

z
drift of electrons in front of the side
wall, in addition to E
θ drift is pointed out in terms of
the plasma maintenance.
Particle Modeling of Ionization and Three-Body Recombination in Fully Ionized Plasmas
Authors: Kenichi Nanbu Kenichi Nanbu , Shigeru Yonemura Shigeru Yonemura , Akira Sasaki Akira Sasaki
Published: October 2002

In optical field ionized (OFI) plasmas, the electron energy distribution is highly deviated from equilibrium distribution; ionization and recombination in such plasmas should be treated using the particle model since the usual concept of a rate constant is not applicable in nonequilibrium. A particle model is proposed for the simulation of ionization and three-body recombination
in fully ionized plasmas of Li3+. The nonequilibrium rate constant is defined and calculated using the cross section for reactive collision, which is derived from the equilibrium rate constant using the inverse Laplace transform. The use of the model, together with the Coulomb collision simulation, makes it possible to examine the relaxation of the electron energy distribution in nonequilibrium systems.
Realistic Etch Yield of Fluorocarbon Ions in SiO2 Etch Process
Authors: Hikosaka Yukinobu , Sekine HisatakaHayashi , Endo HideoTsuboi , Mizutani Naoki
Published: October 2002

The energy distribution and flux of ions striking an rf-biased electrode were measured
by using an rf floating ion energy analyzer. Energies of CF1
+, which was the dominant species,
were distributed over a voltage range of about half the peak-to-peak bias voltage. Energetic
ions with neutral radicals, forming the reactive fluorocarbon polymer layer on a SiO2 film,
affected etching characteristics such as rate and selectivity. To investigate the chemical activity
of the reactive layer, we estimated the etch yield of SiO2 from the given energy distribution of the
ions and the etch rate of SiO2. We found that the energy dependence of the etch yield should be
controlled by precisely regulating the flux and composition of neutral radicals under a given ion
flux, in order to obtain a high etch rate under the actual SiO2 etching conditions.
Conformal Deposition of High-Purity Copper Using Plasma Reactor with H Atom Source
Authors: Jin Hong Jie , Shiratani Masaharu , Nakatake Yasuhiro , Fukuzawa Tsuyoshi , Kinoshita Toshio , Watanabe Yukio , Toyofuku Masaharu
Published: October 2002

We have studied the effects of H atoms on the removal of impurities in Cu thin
films for plasma chemical vapor deposition (CVD) from Cu(hfac)2. In situ Fourier
transform infrared (FT-IR) spectroscopic measurements show that H atoms are
very effective in removing impurities in the film for substrate temperatures above
70°C. While H atoms are important to obtain high-purity Cu films, deposition rate
and film conformality presumably depends on Cu-containing radicals, which are
closely related to the degree of dissociation of Cu(hfac)2. Therefore, we have also
demonstrated independent control of both concentration of H atoms and the degree
of dissociation of Cu(hfac)2 by using a plasma CVD reactor equipped with an H
atom source. Excellent film coverage of above 95% in a trench 0.4 µm wide and
3.25 µm deep is realized by their control.
Ion Bombardment Effects on Boron Nitride Film Synthesis by Reactive Sputtering with Electron Cyclotron Resonance Plasmas
Authors: Masayuki Wakatsuchi Masayuki Wakatsuchi , Yoshiro Takaba Yoshiro Takaba , Kumiko \scshapeKanai Kumiko \scshapeKanai , Yoshio Ueda Yoshio Ueda , Masahiro Nishikawa Masahiro Nishikawa
Published: October 2002

Boron nitride (BN) films with a high cubic phase content have been
synthesized.
The films are deposited by reactive sputtering of a pure boron target in
electron cyclotron resonance (ECR) plasmas and ion bombardment to a
substrate is enhanced by rf biassing of the substrate.
A cubic phase of BN is grown over a certain threshold value of ion
bombardment energy.
The threshold and the cubic phase content depend on the ratio of ion
flux to boron atom flux to the substrate.
The threshold decreases as the ratio increases; however, the cubic
phase content also decreases, particularly in a high ion flux region.
BN films with a high cubic phase content show surface cracking and
delamination because of the high compressive stress induced by ion
bombardment.
An intermediate hexagonal BN layer, of a certain thickness between layer
with high cubic phase content and the substrate prevents surface
cracking and improves film adhesion.
Plasma Copolymerization of Tetrafluoroethylene/Hexamethyldisiloxane and In Situ Fourier Transform Infrared Spectroscopy of Its Gas Phase
Authors: Tatsuru Shirafuji Tatsuru Shirafuji , Yasuo Miyazaki Yasuo Miyazaki , Yuko Nakagami Yuko Nakagami , Yasuaki Hayashi Yasuaki Hayashi , Shigehiro Nishino Shigehiro Nishino
Published: October 2002

Plasma copolymerization of hexamethyldisiloxane
(HMDSO, (CH3)3-Si-O-Si-(CH3)3) and
tetrafluoroethylene (CF2=CF2) was performed
using an RF plasma enhanced chemical vapor deposition method,
for its application to low dielectric constant intermetal dielectrics.
Film structure was investigated by X-ray photoelectron
spectroscopy and Fourier transform infrared (FT-IR) spectroscopy.
Film composition was controlled gradually from that of fluorinated
carbon to organic siloxane by changing the HMDSO mixing ratio.
The films possessed a dielectric constant of less than 2.5
for an HMDSO mixing ratio of less than 10%.
Thermal treatment of the films revealed that the C-F
n
, Si-O-Si,
Si-(CH3)
n
and Si-(CH2)
n
-Si bonds were stable to
400°C, but the C-H2 bonds were not. In situ gas-phase
FT-IR spectroscopy was also performed on the plasma, and the reaction
mechanisms are discussed.
Low-Dielectric-Constant-Film Deposition with Various Gases in a Helicon Plasma Reactor
Authors: Seok-Min Yun Seok-Min Yun , Hong-Young Chang Hong-Young Chang , Kyoung-Suk Oh Kyoung-Suk Oh , Chi-Kyu Choi Chi-Kyu Choi
Published: October 2002

Low-dielectric-constant SiOF films are deposited using O2/SiF4 and O2/FSi(OC2H5)3 mixtures in a
helicon plasma reactor, and good quality films can be obtained without intentional heating or biasing of the substrate.
Optical emission spectroscopy (OES) is used to study the relation between the relative densities of the radicals and
the film properties. The OES data imply that the source gases are highly dissociated above the RF power of 900 W where
the helicon mode is generated. Consequently, the mechanism of helicon plasma chemical vapor deposition (CVD) is
different from that of thermal CVD. In the case of thermal CVD, the source gases react chemically on the
high-temperature substrate and form films. However, in the case of helicon wave plasma CVD, the source gases are highly
dissociated in the high-density plasma and many radicals are produced, that react on the substrate. SiOF films are made
in the case of O2/SiF4 but CF/SiOF composite films are made in the case of O2/FSi(OC2H5)3, where
FSi(OC2H5)3 is highly dissociated in plasma and C participates in the film formation. Films with a low
dielectric constant of below 3.0 can be made.
Deposition of SiNx Thin Film Using µ-SLAN Surface Wave Plasma Source
Authors: Xu Ying-Yu , Ogishima Takuya , Korzec Dariusz , Nakanishi Yoichiro , Hatanaka Yoshinori
Published: October 2002

A slot antenna (µ-SLAN) microwave surface wave plasma source was developed for SiN
x
thin film
preparation. A µ-SLAN-produced argon plasma density up to 1011 cm-3 has been achieved at an axial
position of about 43 cm from the ring cavity at a microwave power of 500 W and a chamber pressure of
0.5 Torr. High-speed deposition of SiN
x
thin film was performed using the µ-SLAN-assisted remote
plasma enhanced chemical vapor deposition method incorporating tris(dimethylamino)silane
(TDMAS) as a monomer source. The film deposition rate increased rapidly up to 270 nm/min when
some hydrogen was mixed in the nitrogen gas and increased from 0 to 1%. A further increase of
hydrogen content, however, only slightly increased the film deposition rate. A high deposition rate of
280 nm/min was obtained when 15% hydrogen was mixed in the nitrogen gas, with the chamber
pressure and microwave power at 1.5 Torr and 500 W, respectively.
Effects of Crossed Magnetic Fields on Silicon Particles in Plasma Chemical Vapor Deposition Process
Authors: Hiroshi Fujiyama Hiroshi Fujiyama , Yoko Maemura Yoko Maemura , Mikio Ohtsu Mikio Ohtsu
Published: October 2002

In order to realize the preparation of large-area uniform
hydrogenated amorphous silicon thin films for solar cells under-dust
particle-free process conditions, the scanning plasma method
(SPM) using a crossed magnetic field has been investigated to
remove silicon particles produced in silane discharge. The silicon
particles collected on the substrates were observed by scanning electron
microscopy (SEM) to identify the crossed magnetic field effects on
particle removal and suppression in the present SPM process. In this
paper, the relationship between the externally applied crossed magnetic
field and the particle behavior in silane plasma are reviewed from the
viewpoint of particle removal and suppression.
Diagnosis of Asymmetric Thermal Plasma Jet Using Computer Tomography Technique
Authors: Sakiyama Satoshi , Fukumasa Osamu
Published: October 2002

In order to clarify the feasibility of application of the
computer tomography technique for the diagnosis of an asymmetrical
plasma jet, the heat transfer flux of the jet is measured using a
water-cooled calorimetric probe. The asymmetric plasma jet is
generated by injecting the feed gas into the jet perpendicular to the
jet axis. The algebraic reconstruction technique (ART) is used as the reconstruction method. With increasing the feed-gas flow rate, the asymmetry of the heat transfer flux profile of the jet is found to increase, by means of the computer tomography technique.
Chemical Kinetic Modelling of Non-Equilibrium Ar-H2 Thermal Plasmas
Authors: G. Beuthe Thomas , Chang Jen-Shih
Published: October 2002

A chemical kinetic model has been constructed to predict the gas and electron
temperature dependence of the neutral and ionic species composition in
Ar-H2 mixtures under thermal plasma conditions. The
model includes electron impact, thermal impact, ion-molecule, and recombination
reactions as well as accounting for diffusion. Important metastable and excited
states of species have been accounted for as well as the presence of neutral
molecules, radicals, and atoms, positively and negatively charged atoms and
molecular ions, and electrons. All relevant electron temperature, gas
temperature and pressure terms have been included.
Calculations were performed for electron and gas temperatures between
300 and 15000 K and various pressures.
Under equilibrium and non-equilibrium conditions, Ar, H2, H,
ArH3
+, Ar+, H+, H- and electrons
were found to be the dominant neutral and charged species.
No significant negative ion concentrations are observed.
Effect of Oxygen Concentration on the Detection of Mercury in an Atmospheric Microwave Discharge
Authors: P. Woskov Kamal Hadidi , J. Flores Guadalupe , Kareen Green Kareen Green , Paul Thomas Paul Thomas
Published: October 2002

A microwave plasma combined with atomic emission spectroscopy is
being developed for real time emission monitoring of metals in smoke
stacks. The plasma is sustained by 1.5 kW, 2.45 GHz microwave
radiation in a gas flow at atmospheric pressure. The addition of
oxygen to a nitrogen gas stream reduces dramatically the emission
intensity of the 253.65 nm mercury transition, while at the same time
it increases the emission intensity of the 405.78 lead line and other
metal transitions. Measurements as a function of oxygen concentration
in the plasma gas stream on the intensity of the 253.65 nm mercury
line and on the excitation temperature, T

e
x
c
, are presented.
Possible mechanisms in the plasma that can effect the emission
strength of the Hg atom are explored. Plasma absorption at 253.65 nm
by ozone is ruled out by UV transmission measurements. The measurements
suggest that a slight cooling of T

e
x
c
with the addition of oxygen,
combined with the sharp electron impact excitation cross section can
explain the observed behavior.
Ozone Generation by a Discharge in Bubbled Water
Authors: Ihara Satoshi , Miichi Tomoaki , Satoh Saburoh , Yamabe Chobei , Sakai Eiji
Published: October 2002

The final goal of this research is to realize the efficient utilization of
radicals such as atomic oxygen, OH radical, and ozone for water
purification. The radicals were generated by a discharge occurring inside
the bubbles produced by a bubbling tube immersed in water. The Blumlein
line, a repetitive pulsed power generator, was used as the power source. In
the experiments, a maximum ozone concentration of approximately 300 ppm was obtained when the repetition rate of pulsed power generator, the
peak value of applied voltage and the gap length were 15 pps,
approximately 30 kV, and 7.5 mm, respectively. Oxygen was used as the
bubbling gas. The time duration of voltage pulse was approximately 200 ns.