bluuebunny/crossref_metadata_2025 huggingface dataset:
Etch Defect Reduction Using SF6/O2 Plasma Cleaning and Optimizing Etching Recipe in Photo Resist Masked Gate Poly Silicon Etch Process
Authors: Mun Seong Yeol , Shin Kyeong Cheol , Lee Sung Soo , Kwak Jong Seok , Jeong Jae Young , Jeong Yang Hee
Published: September 2005

This paper presents a significantly effective new method to reduce defects generated during photo resist (PR) masked gate poly-silicon etch process in decoupled plasma source (DPS) etching reactor. In the new method, etching reactor cleaning by SF6/O2 plasma before processing product wafers is introduced to clear the extreme non-volatile by-products on the reactor surface, which is the source of defects. And, Y2O3 in stead of Al2O3 as reactor material is essential for the application of the SF6/O2 plasma cleaning to suppress instable by-product deposition after the SF6/O2 plasma cleaning. Additionally, the stabilization step in etching recipe is skipped to prevent the abrupt falling of by-products by instable plasma ignition at each etch step. The incorporation of the above three items significantly reduces the etch defects without any process performance shift in PR masked gate poly-silicon etch process using HBr/Cl2/O2 chemicals.
Rise-Time Elongation Effects on Trapped Field and Temperature Rise in Pulse Field Magnetization for High Temperature Superconducting Bulk
Authors: Fujishiro Hiroyuki , Kaneyama Masahiko , Yokoyama Kazuya , Oka Tetsuo , Noto Koshichi
Published: September 2005

Pulse field magnetization (PFM) using a magnetic pulse of B
ex=3.83–5.53 T with various rise times t
r (=6–20 ms) has been performed for the cryocooled SmBaCuO bulk superconductor starting at the initial temperature of 40 K. The time evolutions of temperature T(t) and local field B
L
P(t) have been measured on the bulk surface after applying the magnetic pulse. With increasing t
r, the temperature rise ΔT and the trapped field B
T
P increase for B
ex≤4.70 T and decrease for B
ex=5.53 T. The rise time t
r required to realize the optimum B
T
P has been found to become longer for a smaller pulse field B
ex. From the analyses of the generated heat Q after five successive applications of pulses (Nos. 1–5) with the same amplitude, the Q(No. 5) value, which can be regarded as the viscous loss Q
v, decreases with increasing t
r, due mainly to the decrease in the flux propagation velocity v in the bulk with longer t
r.
Development and Applications of Magnetooptical Measurement System Equipped with a Rotational Resonant Cavity in the Millimeter-Wave Region
Authors: Kimata Motoi , Koyama Keiichi , Ohta Hitoshi , Oshima Yugo , Motokawa Mitsuhiro , Nishikawa Hiroyuki , Kikuchi Kouichi , Ikemoto Isao
Published: September 2005

A rotational resonant cavity equipped with a millimeter vector network analyzer (MVNA) and a 14 T solenoid type superconducting magnet has been developed. The available frequency range is about 50–100 GHz. The temperature can decrease to 1.5 K. The cavity can rotate within the precision of one degree. As an example of the application of the new resonant cavity, we have performed detailed magnetooptical measurements of an organic conductor to estimate the Fermi surface topology. The Fermi surface of the quasi-one-dimensional conductor (DMET)2I3 is discussed.
Influence of Residual Stresses and Their Relaxation on Giant Magnetoimpedance of CoFeSiB Metallic Glasses
Authors: Saad Andrea , García José Angel , Kurlyandskaya Galina , Santos Jesús Daniel , Elbaile Laura
Published: September 2005

The magnetoimpedance effect in Co69Fe4Si15B12 melt-spun amorphous ribbons was studied in the as-quenched state and after low-temperature relaxation annealing at 473 K. The change of the impedance in the external magnetic field depends on the type of effective magnetic anisotropy and its modification by heat treatment. The maximum magnetoimpedance variation is higher in the as-quenched sample (about 420%) than in the annealed sample (about 300%). This behavior is explained to be a result of the change of the anisotropy distribution influenced by the magnetoelastic component of the effective magnetic anisotropy for the samples with well defined longitudinal anisotropy. The high magnetoimpedance effect that shows low hysteresis in the as-quenched state can be considered to be an advantage for the application of these ribbons in small field sensors.
(CeTb)MgAl11O19 Phosphor Particles Prepared by Spray Pyrolysis from Spray Solution Containing Citric Acid and Ethylene Glycol
Authors: Jung Dae Soo , Hong Seung Kwon , Ju Seo Hee , Lee Hyo Jin , Kang Yun Chan
Published: September 2005

(CeTb)MgAl11O19 (CTMA) phosphor particles were prepared by spray pyrolysis from polymeric precursor solutions under severe preparation conditions. Citric acid and ethylene glycol used as polymeric precursors formed as-prepared and post-treated (CeTb)MgAl11O19 phosphor particles with a spherical shape and a dense morphology. The CTMA phosphor particles prepared from polymeric precursor solutions at 1600°C had a completely spherical shape, a dense morphology, and a nonaggregated morphology after post-treatment at 1400°C. The CTMA phosphor particles prepared from the polymeric precursor solution had a lower impurity content than those prepared from a pure aqueous solution. All the phosphor particles prepared from the polymeric precursor solution had higher photoluminescence intensities than those prepared from the pure aqueous solution at all temperatures. The photoluminescence intensity of the CTMA phosphor particles prepared from the polymeric precursor solution was 108% that of the phosphor particles prepared from the pure aqueous solution at 1600°C.
Improvement of Phase Retardation of Wave Plate with Subwavelength Structures by Heat Treatment
Authors: Isano Taisuke , Kaneda Yasushi , Kadoshima Takayuki , Ukaji Emi , Sato Masahide , Ishizuka Ko , Suzuki Noboru
Published: September 2005

Wave plates with subwavelength structures are fabricated by applying semiconductor processes to realize a high-aspect-ratio grating structure with a small linewidth and a large grating step. We have fabricated wave plates with a large phase retardation using a titanium dioxide (TiO2) film. However, the plates have a problem in that a slight deviation in grating step will bring about a large difference in phase retardation because TiO2 has a large refractive index. To solve this problem, heat treatment of the fabricated wave plates was carried out to change the refractive index. As a result, the relationship between the heating temperature and the increasing ratio of phase retardation was determined, which led to the successful control of the optical properties. The effective temperature was 672 to 1072 K through the characterization of the heat-treated plates. By utilizing this process, the yield of manufactured wave plates can be increased greatly.
Tunable Polarization-Dependent Chromatic Dispersion Compensator Using an Unapodized Chirped Fiber Bragg Grating Inscribed on a High-Birefringence Fiber
Authors: Kwon Jaejoong , Kim Sungchul , Roh Sookyoung , Lee Byoungho
Published: September 2005

A novel application of an unapodized chirped fiber Bragg grating inscribed on a high-birefringence fiber is reported. We utilized a dispersionless band of the unapodized grating. The characteristics of the dispersionless band are analyzed using simulations and experiments. We confirm that the band originates from broadband reflections at the input edge of the grating. If an unapodized chirped fiber Bragg grating is inscribed on a high-birefringence fiber, the reflection spectra and the group delays are separated depending on the polarization of the light, hence each group delay curve has a dispersionless band at a different wavelength. In this paper, we show the feasibility of polarization-dependent chromatic dispersion compensation with a single chirped fiber Bragg grating operating at the bandwidth where the dispersion is zero for one state of polarization but not zero for the other polarization state.
A Wavelength-Tunable Erbium-Doped Fiber Double-Ring Laser with Stabilized Single-Frequency Operation
Authors: Yeh Chien-Hung , Chi Sien
Published: September 2005

A stable and tunable fiber double-ring laser based on erbium-doped fiber amplifier (EDFA) has been proposed and experimentally demonstrated. Widely tunable range from 1527 to 1567 nm, the side-mode suppression ratio (SMSR) of >45.6 dB/0.05 nm and the output power of >1.04 dBm in the operating range from 1535 to 1565 nm can be achieved for this ring laser. By applying the double-ring configuration, the ring laser is stabilized. The central wavelength variation of <0.02 nm and the power fluctuation of <0.03 dBm can therefore be retrieved.
Flyer Acceleration by Pulsed Laser and its Application to Shock-Recovery Experiment on MnF2
Authors: Hongo Teruhisa , Matsuda Akitaka , Kondo Ken-ichi , Nakamura Kazutaka G. , Atou Toshiyuki
Published: September 2005

An experimental method using a laser-driven flyer has been developed for a shock-recovery experiment. A laser-driven flyer has been accelerated to a high speed using a plasma-confinement target assembly with a relatively modest laser intensity (<5 GW/cm2) and its acceleration history has been monitored. A shock recovery experiment of rutile-type MnF2 is performed using the laser-driven flyer with a velocity of 1.1 km/s and a metastable phase (α-PbO2-type MnF2) is recovered with a yield of 83.2%.
High-Frequency Response in Ferroelectric BaSrTiO3 Thin Films Studied by Terahertz Time-Domain Spectroscopy
Authors: Mounaix Patrick , Tondusson Marc , Sarger Laurent , Michau Dominique , Reymond Vincent , Maglione Mario
Published: September 2005

We have measured the dielectric properties of BaTiO3–SrTiO3 thin films, deposited on fused silica substrates, in the MHz and THz frequency regions. Different experimental Chemical Vapor Deposition parameters were analyzed to improve dielectric properties of these thin films. In particular, we clarify pressure and oxygen percentages during the deposition of the thin layer. The complex permittivity function of the film was accurately determined between 100 GHz and 1 THz. We show that the real part of the dielectric behavior at very high frequencies follows the same tendency of the low frequency dielectric behavior also measured. These results are correlated to X-ray diffraction and RBS patterns, which show that the cationic ratio (Ba+Sr)/Ti increases from about 0.6 to 0.9 as sputtering pressure changes from 1 to 5 Pa, leading to better dielectric properties.
Interference Ring Patterns from Cholesteric Liquid Crystal Cells
Authors: Huang Chi-Yen , Hu Chao-Yuan
Published: September 2005

An interference ring pattern is observed from cholestric liquid crystal cells. Quételet scattering light interference contributes to the ring, and defect walls among uniform aligned cholesteric liquid crystal domains serve as scatterers in the cell. A simple theory is developed to explain the observed scattering light interference in the far field condition. Changes in interference ring intensities and optical microscope images are investigated. Experimental results show that cell thickness and applied voltage significantly affect the number of defects and hence affect the ring intensity and the clarity of the observed ring pattern. The multiple diffuse reflections and the polarization changes of the incident light beams in the liquid crystal material affect the contrast ratio in the ring image, and the location of a specific order can be directed by controlling the incident angle. The results introduce the possibility of realizing defects and impurities in a liquid crystal device using scattering light interference. The liquid crystal cells may also serve as candidates for producing a conical interference ring.
Novel Photoaligned Twisted Nematic Liquid Crystal Cell
Authors: Huang Dan Ding , Kozenkov Vladimir , Chigrinov Vladimir , Kwok Hoi Sing , Takada Hirokazu , Takatsu Haruyoshi
Published: September 2005

A novel photoaligned twisted nematic liquid crystal display (TN-LCD) cell is fabricated by one-step illumination with oblique nonpolarized UV light of an empty cell with azo-dye layers coated on indium tin oxide (ITO) substrates. If the incident angle is sufficiently large (>75°), the p-polarization of the light is more pronounced for the bottom azo-dye layer in comparison with that for the upper one. Thus, the photo-alignment of the azo-dye layer on the bottom substrate is perpendicular to that of the upper one, and LC directors on the top and bottom substrates also become perpendicular. The method provides a new simple way of manufacturing photoaligned TN-LCDs.
Phenomenological Theory of Hard-Mode Frequency Shift in Ferroelectric Phase Transition
Authors: Ahn Sang-Jin , Kim Jong-Jean
Published: September 2005

Useful relations of hard-mode spectroscopy are rederived from Slater's simplified phenomenological theory of lattice dynamics. The phase transition anomaly in inverse dielectric susceptibility (1/χ), related to the hard-mode frequency shift (ω
Q
) as Δ(χ-1)=Rω
Q

2, can be analyzed to study structural phase transitions associated with a nondegenerate hard mode. This hard-mode frequency shift represents a change in the symmetry-restricted chemical bonding due to the structural phase transition. The effect of phase transition on the respective chemical bonds can be probed to follow the order parameter change by observing frequency shifts of the corresponding vibrational hard mode. The proportionality constant R can be expressed in terms of mode parameters, which may be associated with the reorientational mobility of the dipole clusters in the phase transition system.
Effects of MgO-Buffer Layer on the Structural and Optical Properties of Polycrystalline ZnO Films Grown on Glass Substrate
Authors: Deesirapipat Yuparwadee , Fujita Miki , Sasajima Masanori , Suzuki Ryotaro , Antarasena Choompol , Horikoshi Yoshiji
Published: September 2005

Characteristics of ZnO films grown on glass substrates with various MgO buffer layer thicknesses have been investigated. All the layers are deposited by plasma-assisted molecular beam epitaxy. Without the MgO buffer layer, surface cracks due to the difference in the thermal expansion coefficients between ZnO and the quartz substrate are easily observed. With the MgO buffer layer, the cracks drastically decrease. The surface morphology changes with different MgO buffer layer thicknesses due to the compressive-tensile stress balance. The ZnO films with a medium MgO buffer layer thickness show a dotlike surface. All samples except those with the dotlike surface exhibit c-axis oriented polycrystalline structures. The photoluminescence emission intensity is also improved by increasing the buffer layer thickness until the optimum MgO buffer layer thickness of approximately 150 nm is reached. Few cracks appear with the reduction of the photoluminescence (PL) intensity when the buffer layer thickness is more than the optimum value. All of the as-grown ZnO films without cracks exhibit n-type conductivity.
Model Analysis of Anomalies in Highly Oriented Pyrolytic Graphite Images by Scanning Tunneling Microscope in Air
Authors: Nishikawa Hiroyuki , Mouloudi Halal El , Shiba Hiroaki , Iri Takeo
Published: September 2005

The atomic corrugations of highly oriented pyrolytic graphite (HOPG) were measured in the constant current mode using a scanning tunneling microscope (STM) in air. The apparent corrugations depend on the angular frequency of the vertical vibrational motion of the tip. The tip motion resulted in a forced vibration of the sample surface through the aid of the contact of the tip with the sample surface. In our previous work, we managed to analyze constant height mode images with a simple model of the tunneling current, and reported that the apparent current modulations corresponding to the atomic corrugation are strongly influenced by the elastic deformation of the sample surface [Jpn. J. Appl. Phys. 34 (1995) 578]. In the present paper, a model for the constant current mode is presented taking additionally into consideration the one-dimensional spring deformation model to explain the forced vibration. From this model, well-known anomalies of atomic corrugations in HOPG images can be explained.
Effective Temperature of Au Nanocontacts under High Biases
Authors: Tsutsui Makusu , Taninouchi Yu-ki , Kurokawa Shu , Sakai Akira
Published: September 2005

The effective local temperature of gold nanocontacts under high biases has been evaluated at 77 K by studying the two-level fluctuations (TLFs) of conductance. Upon varying bias from 0.2 to 0.6 V, TLF frequency increases exponentially while the effective contact temperature remains unchanged, which indicates negligible current-induced heating in Au nanocontacts at least up to 0.6 V at 77 K, in accordance with a theoretical model proposed by Todorovet al.[Phys. Rev. Lett. 86 (2001) 3606].
Decomposition of Toluene with Surface-Discharge Microplasma Device
Authors: Seto Takafumi , Kwon Soon-Bark , Hirasawa Makoto , Yabe Akira
Published: September 2005

A surface-discharge microplasma device (SMD) was developed for the decomposition of volatile organic compounds (VOCs) in the gas phase. The device is composed of a microscale-patterned electrode, a dielectric substrate, and a ground electrode. As a result of localized dielectric barrier discharge (DBD), surface-discharge microplasma was generated when a piezoelectric-transformed high voltage (66.7 kHz, 3.5 kV) was applied to the microscale-patterned electrode. The discharge current and voltage characteristics of the DBD were analyzed under atmospheric conditions. Toluene decomposition rate was evaluated by gas chromatography–mass spectrometry and nondispersive IR-absorption CO2 analysis. A decomposition efficiency of more than 99% was achieved in batch experiments. When the SMD was operated in a flow reactor, 30–80% of toluene was reduced with the percentage depending on residence time. The carbon balance between the toluene starting material and the CO2 product indicates that toluene was almost completely decomposed into CO2 by atomic oxygen in the microplasma.
Highly Concentrated Ozone Gas for Preparing Wettable Polyimide Surface
Authors: Koike Kunihiko , Aida Toshihiro , Habuka Hitoshi
Published: September 2005

Highly concentrated ozone gas, of greater than 20%, was applied, for the first time, in order to obtain a stable wettable polyimide film surface. The water contact angle of the polyimide film surface decreased from 60° to nearly 20° after exposure to the highly concentrated ozone gas. The increase in the small water contact angle during storage in ambient air was very gradual, i.e., 5° for over one month. Scanning electron microscopy and the atomic force microscope showed that surface roughening simultaneously occurred. Since the X-ray photoelectron spectra showed an increase in oxygen concentration at the polyimide film surface, the highly concentrated ozone gas is considered to produce a wettable surface by the significant oxidation of the polyimide film chains on the surface.
Electric Field in Solenoids
Authors: Lee Soonchil , Lee Yongkwan , Yu Insuk
Published: September 2005

The time-varying electric field inside a solenoidal coil is measured using a new sensor that minimizes the field disturbance. The experimental results clearly indicate that the main field inside a solenoidal coil is not in the azimuthal direction, but in the axial direction. It is shown that this axial field is generated by surface charges, which are formed to cancel the inductive field inside a conducting wire.
Process Simulation and Residual Stress Estimation of Micro-Electrodischarge Machining Using Finite Element Method
Authors: Murali Meenakshi Sundaram , Yeo Swee-Hock
Published: September 2005

A mathematical model based on heat transfer principles has been developed for the simulation of single-spark machining during micro-electrodischarge machining (µEDM) of a titanium alloy (Ti–6Al–4V). The model is solved by using a commercially available finite element method. A Gaussian distribution of the heat source and temperature-dependent material properties have been used to perform transient thermal analysis to estimate the crater size, the temperature distribution on the workpiece and the residual stress on and near the crater. Simulated crater dimensions and residual stresses were compared with experimentally obtained values by atomic force microscope (AFM) and a nanoindentation technique. The diameter-to-depth ratios of the crater obtained by simulation and by experiment are 3.45 and 3.99, respectively. The simulated stress exceeds the ultimate tensile strength (860 MPa) of the material near the spark center and gradually diminishes as the distance from the center increases. The stress values measured by nanoindentation of the spark-eroded surface are within 300 MPa.
RF Attenuation Characteristics for In Vivo Wireless Healthcare Chip
Authors: Yamada Tomohiro , Uezono Takumi , Okada Kenichi , Masu Kazuya , Oki Akio , Horiike Yasuhiro
Published: September 2005

We investigate a wireless communication system for an in vivo healthcare chip. In this paper, we present measured attenuation characteristics through the human body at several frequencies. In the measurement, we use physiological saline and fresh meat instead of a real human body. From the measured results, we found that 13.56 MHz has an attenuation of 47 dB and is suitable for the proposed system.
Fabrication of Carbon Nanotube and Nanorod Arrays Using Nanoporous Templates
Authors: Huang Shujuan , Shimizu Tomohiro , Sakaue Hiroyuki , Shingubara Shoso , Takahagi Takayuki
Published: September 2005

A simple fabrication process is presented for highly-ordered, highly-oriented carbon nanotube and nanorod arrays by filling alumina nanohole templates with a carbon precursor, polyacrylonitrile (PAN). X-ray photoelectron spectra analysis indicates that PAN changes its chemical structure to sp2 C–C structure after carbonization at 600°C. Raman characterization of the resulting carbon nanostructure demonstrates a high quality graphite structure. The proposed method may be used to develop carbon nanostructure-based devices.
Nanoscale Strained Si/SiGe Heterojunction Trigate Field Effect Transistors
Authors: Chang Shu-Tong
Published: September 2005

Strained Si surrounding the SiGe embedded body on a silicon on insulator (SOI) substrate forms a novel trigate field effect transistor (FET). The mobility in the channel is enhanced due to the strain of the Si channel. The strained Si trigate FET includes an SOI substrate, an SiGe embedded body, a strained Si channel surrounding layer, an oxide layer, a poly-Si gate electrode (or metal gate electrode), a source, and a drain. This novel device with enhanced carrier mobility and heterojunction confinement is demonstrated to show greatly improved performance for n-type metal–oxide–semiconductor (NMOS) by three dimension simulation. The p-type metal–oxide–semiconductor (PMOS) is not improved as much as NMOS due to the buried channel at the Si/SiGe abrupt heterojunction. Using a grade-back layer among strained Si and a relaxed SiGe body can significantly improve the performance of PMOS.
Preparation of Microcrystals of Organic Compounds with Polar Groups and Inorganic Salts by Reprecipitation
Authors: Zhang Zhang , Yongxu Yongxu , Lv Lv , Chunxu Chunxu , Liu Liu , Dabin Dabin , Guo Guo , Liwei Liwei , Fu Fu , Tingming Tingming
Published: September 2005

Reprecipitation is a useful method of preparing organic microcrystals. However, microcrystals of compounds with polar groups are difficult to prepare by this method. A method of preparing microcrystals of organic compounds with polar groups and inorganic salts using isooctane as an organic nonsolvent has been developed. Microcrystals of HMX, NH4NO3 and NH4ClO4 have been successfully prepared. Drop weight impact testing shows that HMX microcrystals of nanoscale size are much less sensitive to impact than HMX bulk crystals.
Atomic Force Microscopy of Mechanical Property of Natural Rubber
Authors: Watabe Hiroyuki , Komura Motonori , Nakajima Ken , Nishi Toshio
Published: September 2005

The changes in the morphology and mechanical property of natural rubber vulcanizates subjected to large strains were studied by atomic force microscopy. Natural rubber was stretched uniaxially at different extension ratios of up to 7.3. The natural rubber formed line structures several micrometers in width along the strain direction in the force field. Each line structure was composed of parts with different hardnesses, which were deformed locally in different manners. It suggested that natural rubber disobeys the assumption of “affine deformation.” It was also found that there exist structures on the nanometer scale. The micron-scale domain structures obtained were composed of nanoscale structures and stress concentration occurring at the boundary between domain structures.
Structural Stability of Si(001) and Ge(001) in External Electric Fields
Authors: Nakamura Jun , Natori Akiko
Published: September 2005

The effects of external electrostatic fields normal to surfaces, E
ext, on the structural stability of Si(001) and Ge(001) have been investigated using first-principles total energy calculations. It has been shown that the c(4×2) surface is more stable than the p(2×2) surface for both Si(001) and Ge(001) even with a finite electric field whose strength is typical of STM experiments. On the other hand, it has been revealed that the energy barrier for dimer flipping, E
B, shows different dependences between the Si(001)- and Ge(001)-(2×1) surfaces: E
B at Si(001) changes in proportion to E
ext, but hardly does at Ge(001). Such a difference is explained by the difference in the rehybridization of buckled dimers between the reconstructed surfaces of Si(001) and Ge(001), which originates from the difference in the s-p separation of valence orbitals between Si and Ge.
Observation of Large-Scale Features on Graphite by Scanning Tunnelling Microscopy
Authors: Pong Wing-Tat , Bendall James , Durkan Colm
Published: September 2005

Superlattice structures and rippling fringes were imaged on two separate pieces of graphite (HOPG) by scanning tunnelling microscopy (STM). We observed the corrugation conservation phenomenon on one of the superlattice structures where an overlayer does not attenuate the corrugation amplitude of the superlattice. Such a phenomenon may illustrate an implication that nanoscale defects a few layers underneath the surface may propagate through many layers without decay and form the superlattice structure on the topmost surface. Some rippling fringes with periodicities of 20 nm and 30 nm and corrugations of 0.1 nm and 0.15 nm were observed in the superlattice area and in nearby regions. Such fringes are believed to be due to physical buckling of the surface. The stress required to generate such structures is estimated, and a possible cause is discussed. An equation relating the attenuation factor to the number of overlayers is proposed.
Particle Adhesion and Removal on EUV Mask Layers During Wet Cleaning
Authors: Lee Sang-Ho , Hong Yi-Koan , Song Jae-Hoon , Park Jin-Goo , Busnaina Ahmed A. , Zhang Guojing , Eschbach Florence , Ramamoorthy Arun
Published: September 2005

Extreme ultraviolet (EUV) masks have a very stringent cleanliness requirement that present new challenges to nanolithography industry. The cleaning of EUV mask surface is required at every exposure level due to the absence of a pellicle layer. In this study, the adhesion and removal of particles on EUV masks is investigated by calculating the interaction force and measuring the adhesion force using atomic force microscopy (AFM). Zeta potential measurements showed that the calculated interaction force was attractive on Si capping layer and Cr absorbed layer for both silica and alumina particle at all pH ranges investigated. However, the measured adhesion force of Si capping layer was similar to that of bare Si at neutral and alkaline pHs. The calculated interaction force of SiO2 buffer layer was most repulsive and the lowest adhesion force was measured. This indicates that the SiO2 buffer layer has a better cleaning efficiency at neutral and alkaline pH. The calculation of interaction force between particle and surface and measurement of adhesion force shows that a lower particle removal efficiency was expected on Cr absorber layer surface.
Depth Profile and Line-Edge Roughness of Low-Molecular-Weight Amorphous Electron Beam Resists
Authors: Hirayama Taku , Shiono Daiju , Matsumaru Shogo , Ogata Toshiyuki , Hada Hideo , Onodera Junichi , Arai Tadashi , Sakamizu Toshio , Yamaguchi Atsuko , Shiraishi Hiroshi , Fukuda Hiroshi , Ueda Mitsuru
Published: September 2005

We have investigated the possibility of using amorphous low-molecular-weight polyphenols as chemically amplified positive-tone electron-beam (EB) resists. Low-molecular-weight polyphenol, 4,4'-methylenebis[2-[di(2-methyl-4-hydroxy-5-cyclohexylphenyl)]methyl] phenol (3M6C-MBSA) as a base matrix, was protected by 1-ethoxyethyl (EE) groups to control the dissolution rate in aqueous 0.26 N tetramethylammonium hydroxide developer. The film distribution in the depth direction for resist components determined with time-of-flight secondary ion mass spectometry (TOF-SIMS) and the Fourier amplitude spectra of line-edge roughness (LER) have been investigated to understand the relationship between them for the resists formulated with 3M6C-MBSA and two photo-acid generators (PAG), triphenylsulfonium perfluoro-1-butanesulfonate (TPS-PFBS) and triphenylsulfonium n-octanesulfonate (TPS-nOS). From these results, it was found that the resist film consisting of TPS-nOS showed more homogeneity in the depth direction of the film than did TPS-PFBS, which showed low surface energy and diffused easily to the resist surface through the matrix during a coating and post-applied bake step. The resist with TPS-nOS indicated a lower LER value of 5.1 nm in the wide frequency range, especially in the lower frequency region below 10 µm-1. Therefore, the homogeneity of the film is one of important factors for LER control.
Detection of Streptavidin-Biotin Protein Complexes Using Three-Dimensional MOSFET in the Si Micro-Fluidic Channel
Authors: Han Dae-Il , Kim Dong-Sun , Park Jee-Eun , Shin Jang-Kyoo , Kong Seong-Ho , Choi Pyung , Lee Jong-Hyun , Lim Geunbae
Published: September 2005

To detect the electrical reaction characteristics of streptavidin-biotin protein complexes, a three-dimensional (3-D) p-channel metal oxide semiconductor field effect transistor (PMOSFET)-type biosensor was fabricated in the convex corner of a micro-fluidic channel by tetramethyl ammonium hydroxide (TMAH) anisotropic etching. Au, which has a chemical affinity with thiol, was used as the gate metal for immobilizing a self-assembled monolayer (SAM). The SAM was used to immobilize streptavidin. The hydroxyl group of SAM was bound with the amine group of streptavidin. After that, streptavidin and biotin were bound by their high affinity (Ka∼1015 Mol-1). The measurements were performed in phosphate-buffered saline (PBS; pH 6.4, 20 mM) solution. Ag/AgCl was used as the reference electrode. The bindings of SAM, streptavidin and biotin caused a variation in the drain current of the 3-D MOSFET. To verify the interaction among the SAM, streptavidin and biotin, surface plasmon resonance (SPR) measurement was performed.
Development of Beam Splitter Using Multilayer Membrane for Extreme Ultraviolet Phase-Shift Microscopes
Authors: Hosokawa Nobuyuki , Watanabe Takeo , Sakaya Noriyuki , Shoki Tsutomu , Hamamoto Kazuhiro , Kinoshita Hiroo
Published: September 2005

The realization of a defect-free mask is a technical problem in extreme ultraviolet lithography (EUVL) technology, which is expected as a next-generation lithography technology. We are therefore proposing and developing the EUV phase-shift microscope for phase-defect inspection. The beam splitter is the key element in this microscope. In this paper, we describe the present situation on the development of the beam splitter.
The most inportant issue in beam splitter development is controlling stress. By controlling Ar gas pressure, we controlled stress and thereby successfully developed the beam splitter.
Contamination Evaluation System for Extreme Ultraviolet Mirrors with the Use of Undulator Radiation
Authors: Niibe Masahito , Kakutani Yukinobu , Kakiuchi Kazuya , Terashima Shigeru , Takase Hiromitu , Gomei Yoshio , Aoki Takashi , Matsunari Shuichi , Kondo Hiroyuki , Fukuda Yasuaki
Published: September 2005

A high-intensity extreme ultraviolet (EUV) irradiation and reflectivity measurement system was developed in order to add a contamination inhibition mechanism to Mo/Si multilayer mirrors for EUV lithography. The system can irradiate EUV light at a high flux density of 500 mW/mm2, and it can measure the reflectivity change in situ. As a first experiment using this equipment, irradiation on a Si-capped multilayer was carried out. In this experiment, the water vapor pressure was changed, and changes in the reflectivity were examined. As a result, the decrease in reflectivity increased with an increase in the water vapor pressure. In the meantime, it was indicated that the decrease in reflectivity at an equal dose reversed when the irradiation intensity was lowered using a filter. As a result of surface analysis, the Si-capping layer was oxidized in the irradiation area, and there was deposition of C in the outer part of the irradiation area.
Feasibility Study of Multiple-Beam Scanning Electron Microscopy for Defect Inspection
Authors: Nakasuji Mamoru , Yoshikawa Shoji , Satake Tohru , Noji Nobuharu
Published: September 2005

Multiple beams are formed around an optical axis and scanned on a specimen. Secondary electrons (SEs) emitted from the scanned points are accelerated by an electrostatic objective lens and deflected by an E cross B (E×B) beam separator to a secondary-electron detector. By scanning over an 80 nm line & space pattern with four beams, Scanning Electron Microscopy (SEM) images are obtained. From these SEM images it is seen that there is no problem with cross-talk from the neighboring beams in multiple-beam SEM where there are plural detectors. The emittance and brightness of the electron gun with a LaB6 spherical cathode are measured to be 163 mrad µm and 1.5×105 A/cm2sr, respectively, for an emission current of 450 µA and a beam energy of 4.5 keV.
A simulation is performed for a combination lens, with a lens, the magnetic gap of which is formed at the specimen side, and an electrostatic lens with an electrode to which a positive high voltage is applied. Based on these electron gun characteristics and simulated aberration characteristics, 8-columns by 8-rows multiple beams with a 160 nA total beam current and a 50 nm resolution are expected. A defect inspection with equivalent pixel frequencies of 4 GHz is expected. This pixel frequency is 10 times larger than that of a commercial available system, and then the multiple-beam SEM is a most promising system for a next-generation inspection.
Highly Accurate Proximity Effect Correction for 100 kV Electron Projection Lithography
Authors: Koba Fumihiro , Yamashita Hiroshi , Arimoto Hiroshi
Published: September 2005

In this paper we provided an adequate approximation to an actual exposure intensity distribution (EID) for 100 kV electron projection lithography (EPL) by using a new function employing 2-Gaussian plus exponential model. We have evaluated correction accuracy of our new model using the optimum EID parameters. The parameters were extracted from measured resist linewidth exposed by using a mask with test patterns. The test patterns were resized by changing nominal EID parameters. We found that by using the new EID function with the optimum parameters the correction accuracy for pattern space dependency was improved by 8 nm. The EID function was especially effective to device patterns that had various line pitches. It was noteworthy that this simple EID function, consisting of only three terms, led to significant improvement in the correction accuracy.
Issues in Nanoimprint Processes: the Imprint Pressure
Authors: Scheer Hella-Christin , Bogdanski Nicolas , Wissen Matthias
Published: September 2005

A technical thermoplastic polystyrene with broad molecular weight distribution was characterised with respect to its thermo mechanical behaviour. In comparison to two other polystyrenes with narrow molecular weight distribution its temperature behaviour was investigated and could be generalised making use of well-known basic common principles of polymer rheology. The role of the temperature and the molecular weight choice with respect to an imprint process was contrasted to the role of the imprint pressure, which is a free parameter without impact on polymer characteristics. Pressure determines the initial shear rate in the process. Correspondingly simulations of the course of an imprint were performed, where shear thinning was assumed and the viscosity changed throughout the process according to the measured polymer behaviour. Two different filling situations were investigated, bottom up filling of the stamp cavities and lateral filling of the stamp cavities. In both cases the simulations show a quick decrease of the polymer height within the first seconds of the imprint. Shear rate effects suggest being effective to end up with very short processing times during thermal imprint under appropriate pressure with medium molecular weight thermoplastics. This is an interesting approach towards high throughput nanoimprint processes.
Position-Controlled Carbon Fiber Growth Catalyzed Using Electron Beam-Induced Chemical Vapor Deposition Ferrocene Nanopillars
Authors: Mukawa Takahito , Okada Satoshi , Kobayashi Ryota , Fujita Jun-ichi , Ishida Masahiko , Ichihashi Toshinari , Ochiai Yukinori , Kaito Takashi , Matsui Shinji
Published: September 2005

We demonstrated nanotube growth on a position-controlled catalyst using electron beam-induced chemical vapor deposition (EB-CVD) ferrocene nanopillars. While solid phase graphitization was induced at 650°C, iron nanoparticles only appeared on the surface by eroding the surrounding graphite triggered by the gas phase carbon fiber growth, at a temperature higher than 800°C using ethanol vapor. The precise position control achieved by EB-CVD directly reflected that of carbon fiber growth, which is a promising position-controlled carbon nanotube growth method for future device applications.
Porous Materials with Ultralow Optical Constants for Integrated Optical Device Applications
Authors: Chen Hsuen-Li , Hsieh Chung-I , Cheng Chao-Chia , Chang Chia-Pin , Hsu Wen-Hau , Wang Way-Seen , Liu Po-Tsun
Published: September 2005

Ultralow dielectric constant (<2.0) porous materials have received much attention as next-generation dielectric materials. In this study, optical properties of porous-methyl-silsesquioxane(MSQ)-like films (porous polysilazane, PPSZ) were characterized for optical waveguide devices applications. Measured results indicate that the refractive index is decreased to approximately 1.320 as the hydration time exceeds 24 h. The measured refractive index is about 1.163 at a wavelength of 1550 nm. PPSZ films have low absorption in the 500 to 2000 nm wavelength regime. Because of their relatively low refractive index and low absorption over a large spectral regime, PPSZ films can be good cladding materials for use in optically integrated devices with many high-refractive-index materials such as silicon oxide, silicon nitride, silicon, and polymers. We demonstrate two structures, ridge waveguides and large-angle Y-branch power splitters, composed of PPSZ and SU8 films to illustrate the use of low dielectric constant (K) cladding materials. The simulation results indicate that the PPSZ films provide better confinement of light. Experimentally, a large-angle Y-branch power splitter with PPSZ cladding can be used to guide waves with the large branching angle of 33.58°.
First-Principles Calculations of Atomistic Behaviors in Ni/Al (001) and Al/Ni (001) System
Authors: Kim Chiho , Chung Yong-Chae
Published: September 2005

Using first-principles calculations, atomistic behaviors such as surface diffusion and incorporation at the junction interface of Ni and Al multilayers were investigated. Both Ni adatoms on the Al (001) surface and Al adatoms on the Ni (001) surface favored a hollow site as their adsorption site. The adsorption energies were 7.00 eV for the Ni/Al (001) and 5.52 eV for the Al/Ni (001) system. Surface diffusion after the hollow site adsorption required 1.98 eV and 0.76 eV for both systems, respectively. The energy barrier for the incorporation of Ni adatoms into the substitutional site of the Al substrate was calculated to be very low, 0.29 eV, and an energy gain of 0.18 eV was obtained after the incorporation. In contrast, for the Al/Ni (001) system, the energy barrier for the incorporation was 0.82 eV, and the total energy of 0.07 eV increased after the process.
Study of IC Compatible On-Chip Thermoelectric Coolers
Authors: Kong Seong-Ho , Wijngaards Davey D. L. , Wolffenbuttel Reinoud F.
Published: September 2005

A thin-film-based thermoelectric micro-cooler has been studied and realized using the standard integrated circuit (IC) fabrication technology and bulk micromachining technology in sequence. The whole fabrication process is kept IC compatible by postponing potassium hydroxide (KOH) etching step to the last part of the fabrication sequence. Considering the fabrication compatibility, polycrystalline silicon germanium (polySiGe) is chosen as thermoelectric material even though bismuth telluride (Bi2Te3) is one of the most effective thermoelectric materials. The influence of non-idealities on device performance, such as Joule heating due to contact resistance and parasitic heat loss through supporting membrane, is analyzed. The characterized thermoelectric, thermal and electric properties of the fabricated polySiGe thermoelectric material correspond well to those from literatures. Measured cooling performance demonstrates that an on-chip micro-cooler can be applied for thermal stabilization near ambient temperature.
Development of Three Dimensional LIGA Process to Fabricate Spiral Microcoil
Authors: Mekaru Harutaka , Kusumi Shinji , Sato Noriaki , Shimizu Masami , Yamashita Michiru , Shimada Osamu , Hattori Tadashi
Published: September 2005

The LIGA process has been developed as a 2.5-dimensional processing method on Si wafers to date. However, we have succeeded in extending the LIGA process to 3D for the first time. 3D-LIGA was achieved by the technical development of 3D X-ray lithography and worm injection molding replication technology with unscrewing. These technologies began from the development of equipment and have developed into quite original technologies. By combining this 3D-LIGA process with a metallization technique that consists of flat and smooth electroplating and isotropic chemical etching, a spiral copper microstructure with a linewidth of 10 µm, a pitch of 20 µm and a thickness of 2 µm was formed on a cylindrical surface made from LCP with a length of 1 mm and a diameter of 0.48 mm. Furthermore, we applied the process to fabricate a spiral microcoil and estimated the electrical properties of the microcoil. The numbers of turns were 15, the inductance was 91 nH and the quality factor was 5.8 for a frequency of 1 GHz. Direct-current resistance was measured as 99 Ω.
InAs Nano-Dot Array Formation Using Nano-Jet Probe for Photonics Applications
Authors: Ohkouchi Shunsuke , Nakamura Yusui , Nakamura Hitoshi , Asakawa Kiyoshi
Published: September 2005

We propose herein a new nano-probe-assisted technique that enables the formation of site-controlled InAs quantum dots. High-density two-dimensional indium (In) nano-dot arrays on a GaAs substrate were fabricated using a specially designed atomic-force-microscope probe, referred to as the Nano-Jet Probe. This probe has a hollow pyramidal tip with a submicron-sized aperture at the apex and an In-reservoir tank within the stylus. A voltage pulse was applied between the pyramidal tip and the sample to extract In clusters from the reservoir tank within the stylus through the aperture, resulting in In nano-dot formation. These In nano-dots were converted directly into InAs arrays by the subsequent annealing with irradiation of arsenic flux. The proposed technique has potential applications in photonics, including regular arrays of quantum bits and single photon emitters for quantum computers and quantum communications.
Deposition of Ru Thin Films from Supercritical Carbon Dioxide Fluids
Authors: Kondoh Eiichi
Published: September 2005

Ruthenium has been of interest for application in ULSI capacitor electrodes and more recently as a barrier metal against Cu diffusion. Thin-film deposition from supercritical CO2 has gained particular attention as a new deposition technique that provides nano-penetration capability and a possibility of developing new deposition chemistries. However, few papers have been published on this technique. In this article, first, the deposition characteristics of Ru thin films using H2 reduction chemistry were described. It was found that Ru films grow only on conductive surfaces when H2 reduction chemistry was employed. These films can be beneficial for some specific applications; however they are not very much favored for general deposition technology. Second, we report that Ru films, oxygen-containing Ru films in fact, grew on dielectric/non-conductive surfaces when oxidative chemistry was used. O3 was used as an oxidant for thin film deposition from supercritical fluids for the first time. The use of O3 promotes heterogenous nucleation and increases the amount of oxygen in the films. Oxygen-containing Ru was reduced by another reduction run using supercritical CO2.
Outgassing Characteristics of Low-Molecular-Weight Resists for Extreme Ultraviolet Lithography
Authors: Hada Hideo , Hirayama Taku , Shiono Daiju , Onodera Junichi , Watanabe Takeo , Lee Seung Yoon , Kinoshita Hiroo
Published: September 2005

We discuss the outgassing characteristics under extreme ultraviolet (EUV) exposure for a new resist system based on amorphous low-molecular-weight (Mw) polyphenols consisting of 4,4'-methylenebis[2-[di(2-methyl-4-hydroxy-5-cyclohexylphenyl)]methyl] phenol (3M6C-MBSA) compared with polyhydroxystyrene. (PHOST) The outgassing characteristics of the photoresist based on the PHOST resin were better than those of the photoresist based on 3M6C-MBSA as the base material. However, when the same polymer was reacted with a protecting group, the outgassing characteristics were reversed. The decomposition reaction mechanism under EUV exposure is discussed on the basis of results from both mass spectrometry and FT-IR measurements. The results indicate that the reactions of 3M6C-MBSA (Resist B) and PHOST (Resist D) under EUV exposure have different mechanisms. It was confirmed that the decomposition of the molecular backbone is the main reaction for 3M6C-MBSA, whereas the decomposition of the protective group is the main reaction for PHOST.
Dependence of Acid Yield on Acid Generator in Chemically Amplified Resist for Post-Optical Lithography
Authors: Nakano Atsuro , Okamoto Kazumasa , Yamamoto Yukio , Kozawa Takahiro , Tagawa Seiichi , Kai Toshiyuki , Nemoto Hiroaki
Published: September 2005

Acid generators are a key component of chemically amplified (CA) resists. They have been intensively investigated during the development of CA photoresists. However, the role of acid generators in acid generation processes is different between photoresists and electron beam resists. In this study, the dependence of acid yield on the kind of acid generator was investigated in CA resists for post-optical lithography. On exposure to ionizing radiation, a difference in acid yield was observed among four kinds of acid generator. The role of acid generators and their reaction mechanisms were discussed.
Photoluminescence Analysis of White-Light-Emitting Si Nanoparticles Using Effective Mass Approximation Method
Authors: Lee Soojin , Cho Woon Jo , Kim Yang Do , Kim Eun Kyu , Park Jae Gwan
Published: September 2005

White-light-emitting Si nanoparticles were prepared from the sodium silicide (NaSi) precursor. The photoluminescence of colloidal Si nanoparticles has been fitted by effective mass approximation (EMA). We analyzed the correlation between experimental photoluminescence and simulated fitting curves. Both the mean diameter and the size dispersion of the white-light-emitting Si nanoparticles were estimated.