bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser-Produced Plasma Light Source Development for Extreme Ultraviolet Lithography
Authors: Komori Hiroshi , Soumagne Georg , Abe Tamotsu , Suganuma Takashi , Imai Yousuke , Someya Hiroshi , Takabayashi Yuichi , Endo Akira , Toyoda Koichi
Published: February 2005

We present recent results of our laser-produced plasma light source development for next-generation lithography. The plasma target of the extreme ultraviolet (EUV) source system is a liquid xenon jet and the driver laser is a 600 W Nd:YAG laser operating at a repetition rate of 10 kHz. A EUV output power of 2.2 W at 13.5 nm (2% bandwidth, 2π sr) having a stability of 0.72% (1σ, 50-pulse moving average) has been achieved. Related to future collector mirror lifetime considerations, fast ions from the laser-produced plasma have been characterized by time-of-flight (TOF) measurements. Using a low repetition rate 8-ns, 100-mJ Nd:YAG laser Xe+ to Xe6+ ions were observed with Xe2+ being the main charge state. In addition, the effects of fast ions on Mo/Si multilayer mirrors have been studied using a Xe ion gun. Ion sputtering of the multilayer structure is the main damage mechanism but layer boundary mixing and surface roughness increase are also observed.
Evaluation of Mask Soaking Performance in a Thermally Stabilized Vacuum Chamber in an Electron Beam Mask Writer
Authors: Mitsui Soichiro , Akeno Kiminobu , Ogasawara Munehiro , Tojo Toru
Published: February 2005

A temperature difference between a mask and a writing environment, which occurs during mask loading, is one of the most significant sources of the mask image placement error. The temperature of the mask has to be adjusted in a thermal chamber. To realize a rapid and highly accurate thermal soaking process, we constructed a new thermally stabilized vacuum chamber with an improved thermal soaking efficiency and evaluated its performance. The chamber is equipped with the top and bottom thermal stabilization plates (TSPs). It was found that the soaking time is largely dependent on the emissivities of the TSPs. The soaking relaxation time of less than 0.4 h is achieved. The thermal stability of the mask after soaking is 0.004°C (3σ) for 12 h. It was also found that a high TSP emissivity is effective in reducing the influence of the temperature variation of the environment on the mask, and the temperature variation of the mask is reduced to approximately 28% of that of the environment. A quick soaking and stable temperature holding of the mask are realized.
65 nm Device Manufacture Using Shaped E-Beam Lithography
Authors: Pain Laurent , Jurdit Murielle , Laplanche Yves , Todeschini Jérôme , Leininger Hugues , Tourniol Sonia , Faure Romuald , Bossy Xavier , Palla Ramiro , Beverina Alessio , Broekaart Marcel , Judong Fabienne , Brosselin Karine , Depoyan Linda , Friec Yannick Le , Leverd Francois , Jonghe Veronique De , Josse Emmanuelle , Hinsinger Olivier , Brun Philippe , Henry Daniel , Woo Michael , Stolk Peter , Tavel Brice , Arnaud Franck
Published: February 2005

In the frame of the ALLIANCE program between Motorola, Philips Semiconductors and STMicroelectronics, electron beam direct write (EBDW) lithography based on shaped beam projection is employed to start quickly an aggressive 65 nm program for the printing of all critical levels. This paper reviews the economical opportunities offered by the introduction of electron beam (E-Beam) lithography for prototyping and advanced research and development applications. EBDW process integration capabilities are also demonstrated, confirming after electrical validation, the real possibilities of EBDW solution for application specific on integrated circuit (ASIC) manufacturing.
Fabrication and Characterization of Magnetic Media Deposited on Top or Side Edges of Silicon Dots
Authors: Landis Stéfan , Rodmacq Bernard , Bayle-Guillemaud Pascale , Baltz Vincent , Diény Bernard
Published: February 2005

Arrays of lines and dots were patterned on silicon substrates by electron beam lithography and reactive ion etching. Co/Pt multilayers were sputter-deposited on these patterned substrates to realize perpendicular patterned media for ultra high-density magnetic recording. Magnetic material thus covers the top of the lines and dots, the bottom of the grooves between nanostructures, and to a lesser extent, the sidewalls. Magnetic properties were characterized by both macroscopic and magnetic force microscopy experiments. From the results obtained from high-resolution transmission electron microscopy (TEM) experiments, we propose a new approach for realizing patterned magnetic media using the side edges instead of the top of the dots.
Graphitized Wavy Traces of Iron Particles Observed in Amorphous Carbon Nano-pillars
Authors: Fujita Jun-ichi , Ishida Masahiko , Ichihashi Toshinari , Ochiai Yukinori , Kaito Takashi , Matsui Shinji
Published: February 2005

We show evidence of solid-phase nanotube growth where traces of iron nano-particles were graphitized in an amorphous carbon nano-pillar fabricated by electron beam induced chemical vapor deposition (EB-CVD). The random walk of iron particles in the carbon nano-pillar caused continuous growth of wavy graphite tubes behind the iron particles as they moved during vacuum annealing at 800°C for 30 min. The graphite sheet in this solid-phase graphitization seemed to be produced at the tail of the iron nanoparticles, and some of the graphite tubes were multi-wall ones containing bamboo-joint-like cap sheets.
Formation of Electrical Interconnects by Self-Trapping of Deoxyribonucleic Acid Molecules
Authors: Hwang Jong Seung , Hwang Sung Woo , Ahn Doyeol
Published: February 2005

The formation of electrical interconnection is proposed and realized using thiol-modified 60 base pairs of poly-(dG) and poly-(dC) deoxyribonucleic acid (DNA) molecules by self-trapping method. DNA molecules are synthesized by annealing 60 base pairs of poly-(dG) and poly-(dC) single strands with thiol groups at both 5' and 3' ends in deionized water at 97°C. Thiol-modified DNA molecules are self-trapping with Au molecules and form a good electrical interconnection between the Au metal electrodes without any external physical force. Transport measurements of a particular sample show resistance values of interconnection of approximately 10 MΩ. The self-trapping method by thiol-modified DNA molecules could be a very promising technique for the interconnection of nanometer-scale devices.
Precise Control of Nanowire Formation Based on Polysilane for Photoelectronic Device Application
Authors: Tsukuda Satoshi , Seki Shu , Saeki Akinori , Kozawa Takahiro , Tagawa Seiichi , Sugimoto Masaki , Idesaki Akira , Tanaka Shigeru
Published: February 2005

A High-energy single ion trajectory in a Si-based polymer thin film produces a cross-linked polymer nanowire with the length of 10–1000 nm and the thickness of 4.0–19.4 nm (radius of the cross section). The energy density deposited by incident ions and the molecular weight of the target polymer materials principally determine the thickness of the nanowires at any discrete radius in this range. Surface treatment of a substrate completely controls the adhesion of the nanowires, which makes it possible to pattern the nanowire distribution on the substrate. Nanogap platinum electrodes with 100 nm gap width are fabricated on the nanowire dispersed SiO2 substrate by a lift-off method with electron beam lithography techniques. Current-voltage analysis of the nanowires in the gap clearly indicates intrinsic semiconductive features based on crosslinked polysilanes.
Molecular Dynamics Simulation at the Early Stage of Thin-Film Deposition: Al or Co on Co(111)
Authors: Kim Sang-Pil , Lee Seung-Cheol , Lee Kwang-Ryeol , Chung Yong-Chae
Published: February 2005

The growth mechanisms at the early stage of thin-film deposition were quantitatively investigated using the molecular dynamics method, focusing on the cases of Al and Co on an fcc-Co(111) system. In the case of Al on Co(111), Al adatoms were grown basically in the layer-by-layer growth mode. Moreover, this growth behavior became more obvious with increasing substrate temperature from 80 K to 300 K. In the case of Co on Co(111), Co adatoms apparently favored the island growth mode at a low incident energy. By increasing the energy, however, the tendency towards the layer-by-layer growth mode highly increased. These could be explained by the difference in surface diffusion barrier between the two cases.
Electrical Characterization of InAs/InP Self-Assembled Quantum Dots by Deep-Level Transient Spectroscopy
Authors: Kim E. K. , Kim J. S. , Hwang H. , Park K. , Yoon E. , Kim J. H. , Park I.-W. , Park Y. J.
Published: February 2005

We have investigated the confined energy level of InAs quantum dots embedded in InP layer using deep-level transient spectroscopy (DLTS) measurement. The higher temperature for the capping layer growth yields a low activation energy (E
a=0.56 eV) and a low barrier height (E
eB=0.18 eV) whereas the lower temperature yields a high activation energy (E
a=0.82 eV) and high barrier height (E
eB=0.52 eV). It was found that the higher temperature for the growth of the capping layer provides a condition for enhancing the confinement energy in InAs QDs/InP structure.
Effects of InGaAs Insertion Layer on the Properties of High-Density InAs/AlAs Quantum Dots
Authors: Park Se-Ki , Tatebayashi Jun , Arakawa Yasuhiko
Published: February 2005

We studied the influence of an InGaAs insertion layer (IL) on the structural and optical properties of InAs/AlAs quantum dots grown on GaAs substrates by metalorganic chemical vapor deposition. We also reviewed our previous results to compare the effects of the InGaAs IL. The linewidth of the luminescence was achieved at 27 meV using the InGaAs IL at room temperature. The dot density directly grown on AlAs was 1.6×1011/cm2, and decreased to 1.1×1011/cm2 and 5.3×1010/cm2 for dots grown on a 3.5 ML-GaAs IL and a 3.5 ML-InGaAs IL. This is attributed to the reduction in the AlAs effect, which forms high-density quantum dots, as the IL overgrown on a matrix layer.
Characterization of Dipalmitoylphosphatidylcholine/Cholesterol Langmuir-Blodgett Monolayers Investigated by Atomic Force Microscopy and Fourier Transform Infrared Spectroscopy
Authors: Kim Yong-Hoon , Tero Ryugo , Takizawa Morio , Urisu Tsuneo
Published: February 2005

The addition effects of cholesterol on the dipalmitoylphosphatidylcholine (DPPC) Langmuir-Blodgett (LB) monolayer have been investigated by atomic force microscopy (AFM) and infrared reflection absorption spectroscopy (IRRAS). The phase transformation from pure DPPC to the DPPC/cholesterol phase proceeds through two stages: initial drastic changes in the surface morphology and the conformation of the DPPC acyl chains below 10% cholesterol, and the gradual homogenization of the morphology towards the liquid-order phase up to 35% cholesterol. The IRRAS peak position indicates that the conformational disorder of the acyl chain becomes almost that of the liquid level at 10% cholesterol addition. In the homogeneous liquid-order phase at 35% cholesterol, the terminal methyl groups of the DPPC are aligned in good order similarly to the solidlike gel phase, whereas the acyl chains have a liquid-level disordered conformation.
Development of Insulated Conductive Probes with Platinum Silicide Tips for Atomic Force Microscopy in Cell Biology
Authors: Akiyama Terunobu , Gullo Maurizio R. , Rooij Nicolaas F. de , Tonin Andreas , Hidber Hans-Rudolf , Frederix Patrick L. T. M. , Engel Andreas , Staufer Urs
Published: February 2005

A microfabrication process of a multifunctional probe is introduced for atomic force microscopy and various electrochemical measurements on biological samples in buffer solution. The silicon nitride probes have a spring constant lower than 0.1 N/m and a conductive tip, which is tightly insulated except at the apex. The conductive core of the tip consists of Pt
x
Si
y
and shows a typical radius of curvature of 15 nm. A simultaneous measurement of topography and electrical current on graphite in air was demonstrated.
Dot Array Microoptics for Lighting Panel Using Synchrotron Radiation Lithography
Authors: Utsumi Yuichi , Minamitani Megumi , Hattori Tadashi
Published: February 2005

The lighting-panel (LP) for liquid crystal displays (LCDs), which leads the light from the illuminating light emitting diode (LED) to the front panel, is one of the key parts of personal digital assistants (PDAs) for decreasing the power consumption. We developed a high luminosity LP for LCDs with accurate three dimensional microstructures using synchrotron radiation lithography, and their optical properties were also evaluated using the luminosity distribution measurement. The mean luminosity and the luminescence efficiency were more than 800 cd/m2. It is notable, from the simulation results, that the mean luminosity for the LP with trapezoidal cylindrical dots increases to 1.5 times higher than that of the LP with cylindrical dots. Qualitatively, the measured result corresponds well with the simulated results.
Cantilever-Type Microelectromechanical Systems Probe Card with Through-Wafer Interconnects for Fine Pitch and High-Speed Testing
Authors: Kim Bong-Hwan , Kim Hyun-Chul , Chun Kukjin , Ki Junghee , Tak Yongsug
Published: February 2005

A new microelectromechanical systems (MEMS) probe card made of electroplated nickel cantilevers, which has compliant structure, with through-wafer interconnections for IC testing is developed. The measured contact resistance was less than 0.5 ohm and leakage current was approximately 0.13 nA between tips and pads. In addition, planarity of tips and the alignment of x- and y-axes were satisfied with conventional needle probe card performance. Therefore, this probe card is suitable for wafer-level burn-in testing and function testing of memory and RF devices. In particular, since through-wafer interconnection can offer the shortest signal line path and reduce signal delay, it is possible to implement fine pitch and high-speed devices. The probe was fabricated with the 4-inch silicon substrate.
Deposition of Cu and Ru Thin Films in Deep Nanotrenches/Holes Using Supercritical Carbon Dioxide
Authors: Kondoh Eiichi
Published: February 2005

Supercritical CO2 behaves like both a gas and a liquid, and posseses unique features such as nanopenetration capability, high diffusivity, and solvent ability. The technique described in this paper uses the supercritical CO2 as a reaction medium for thin film growth and realizes filling or coating of nanofeatures with conducting metals. In this paper, we demonstrate the possibilities of this technique in Cu and Ru thin film deposition. A basic approach to achieving Cu metallization of deca-nanometer trenches or vias were studied. Ru, a promising material for capacitor electrodes and also a new candidate for the next-generation Cu barrier, was successfully deposited and its deposition characteristics were studied. Filling capability and the possibility of conformal deposition were also demonstrated as well as the fabrication of a Cu\Ru stack.
Incident Angle Dependence of O2 Cluster Ions on Ta2O5 Thin Film Properties
Authors: Inoue Shinsuke , Toyoda Noriaki , Tsubakino Harushige , Yamada Isao
Published: February 2005

Ta2O5 dielectric films were deposited on Si and quartz substrates by O2 gas cluster ion beam (O2-GCIB) assisted deposition at various incidence angles. The film structure and optical properties were significantly influenced by incidence angle. For films deposited using O2-GCIB at 7 keV energy, when the incidence angle was smaller than 30° from the surface normal, a very smooth and dense film was realized and there were no significant difference in optical properties as the films deposited at normal incidence. However, when the incidence angle was higher than 45°, surface roughness increased and ripples were formed on the film surface. At a higher acceleration energy, which induces the sputtering of materials, previous reports have shown that in the case of Ar GCIB, ripple formation has been observed at an incidence angle larger than 45°. The same result was observed in the case of O2 cluster ion beam assisted deposition.
Control of Selectivity between SiGe and Si in Isotropic Etching Processes
Authors: Borel Stéphan , Arvet Christian , Bilde Jeremy , Caubet Véronique , Louis Didier
Published: February 2005

The selectivity between SiGe and Si has been investigated in chemical dry etching. Starting from a pure CF4 process that etches SiGe with a good selectivity to Si, the modification of the gas mixture was studied with the aim of understanding the way these materials are etched in the presence of O2, N2 and/or CH2F2. Passivation phenomena were used to show that invert selectivities can be obtained. Their combination leads to ultrahigh Si:SiGe selectivity.
Step-and-Repeat Photo-Nanoimprint System Using Active Orientation Head
Authors: Hiroshima Hiroshi , Komuro Masanori , Kurashima Yuichi , Kim Sang Hoon , Muneishi Takeshi
Published: February 2005

An active orientation head was designed and installed into a step-and-repeat photo-nanoimprint system. The characteristics of the passive part of the active orientation head and compliant contact function as a basic function were evaluated. Feedback control of the active orientation head resulted in 50% load deviation at four locations to within 10%. In addition, asymmetrical load control was realized, which is one of the additional functions of the active orientation head. The automatic photo-nanoimprint sequence was demonstrated, in which the imprint load was controlled to within 1.3% of the target value. In 50 min operation, 25 dies were imprinted on a 4-inch wafer. Bright spots are visible to the eye in the dark-field illumination at each location where patterns should be found. Similar patterns 100–300 nm wide on different dies were observable by optical microscopy. Scanning electron microscope revealed smooth patterns with a half pitch of 100 nm fabricated by the step-and-repeat photo-nanoimprint system.
Reducing Photocurable Polymer Pattern Shrinkage and Roughness during Dry Etching in Photo-Nanoimprint Lithography
Authors: Kim Sang Hoon , Hiroshima Hiroshi , Inoue Seiji , Kurashima Yuichi , Komuro Masanori
Published: February 2005

When we apply a photocurable polymer to photo-nanoimprint lithography, dry etching is necessary to remove the remaining photocurable polymer after imprinting. During dry etching, it is necessary to achieve pattern profiles with small pattern shrinkage, smooth surface, and low edge roughness. Room-temperature etching resulted in serious pattern shrinkage, but this was markedly reduced by substrate cooling (temperature -120°C). We obtained pattern shrinkage ranging from a maximum of 23 nm to a minimum of 4 nm under optimum etching conditions. We found that the surface of the photocurable polymer became rough and a large amount of polymer residue still remained after removing the remaining photocurable polymer. We obtained a smooth substrate surface by increasing both the RF power and total flow rate of the SF6/O2 gas mixture. Under optimum etching conditions, we obtained fine etch profiles of the photocurable polymer with a surface roughness of 2.5 nm, reduced pattern shrinkage, and a 3 nm line edge roughness.
Application of Laser Scan Lithography to Fabrication of Microcylindrical Parts
Authors: Joshima Yuuki , Kokubo Tadashi , Horiuchi Toshiyuki
Published: February 2005

Laser scan lithography on fine cylindrical specimens is investigated, and various microparts are fabricated successfully by etching the specimens masked by resist patterns. First, the uniform coating of resist films on fine cylindrical specimens is investigated, and a new method is developed. In the new method, the specimen is dipped vertically in the resist bottle, and the bottle is moved downward. Although the coating thickness of PMER P AR-900 varies from 1.5 to 28 µm depending on the material and the specimen diameter, it is controllable by adjusting the moving speed of the bottle. Next, a test exposure system is manufactured for patterning on a cylindrical specimen. A blue laser light with a wavelength of 473 nm is condensed into a diameter of 6–43 µm on the specimen, and the beam spot is relatively scanned by moving and rotating the specimen. Exposed pattern widths are controlled by changing the scan speeds. Finally, metal specimens with resist patterns are wet-etched in ferric chloride solution, and various microparts such as a screw, a turbine impeller, and a drill are fabricated successfully.
Bilayer Resist Method for Room-Temperature Nanoimprint Lithography
Authors: Nakamatsu Ken-ichiro , Watanabe Keiichiro , Tone Katsuhiko , Katase Tetsuya , Hattori Wataru , Ochiai Yukinori , Matsuo Takahiro , Sasago Masaru , Namatsu Hideo , Komuro Masanori , Matsui Shinji
Published: February 2005

A compact nanoimprint lithography (NIL) apparatus using the driving power of a servomotor has been newly developed. A bilayer resist method using hydrogen silsequioxane (HSQ) as a top layer and AZ photoresist as a bottom layer has been proposed to achieve high-aspect resist patterns on a nonflat surface for room-temperature nanoimprint lithography (RT-NIL). The etching rate ratio of HSQ to AZ photoresist was higher than 100 for O2 reactive ion etching (RIE), indicating that the HSQ top layer has sufficient etching tolerance. We have achieved the high-aspect nanostructure patterns of 100-nm-linewidth and 1-µm-height using the NIL apparatus developed here.
Barrier-Height-Enhanced n-GaN Schottky Photodiodes Using a Thin p-GaN Surface Layer
Authors: Jiang Hao , Egawa Takashi , Ishikawa Hiroyasu , Dou Yanbo , Shao Chunlin , Jimbo Takashi
Published: February 2005

A p
+-GaN surface layer of 15 nm was incorporated in n-GaN Schottky photodiode to enhance the effective Schottky barrier height. A barrier height of 1.09 eV for the normal n-GaN Schottky photodiode was increased to the effective barrier height of 1.16 eV. The resulting photodiodes show a reverse dark current density of as low as 4.8×10-10 A/cm2 at -2 V bias, which is about three orders of magnitude lower than that of the normal n-GaN Schottky photodiode. The lower dark current leads to a significant improvement in the visible rejection ratio. A peak responsivity of 107 mA/W was obtained at -2 V bias under the incident power density of 10 µW/cm2, corresponding to an external quantum efficiency of 38%.
Homoepitaxy of 4H-SiC on Trenched (0001) Si Face Substrates by Chemical Vapor Deposition
Authors: Chen Yi , Kimoto Tsunenobu , Takeuchi Yuichi , Malhan Rajesh Kumar , Matsunami Hiroyuki
Published: February 2005

The homoepitaxy of 4H-SiC on trenched substrates by chemical vapor deposition has been investigated. Two types of 4H-SiC (0001) substrates inclined 8° toward [112̄0] or [11̄00] were used. 4H-SiC growth near trenches perpendicular to the off-direction tended to be highly asymmetric due to the influence of step flow growth, and the (0001) facet was formed along the downstream side of trenches by step flow. In contrast, the growth near trenches parallel to the off-direction was symmetric. The strong influence of C/Si ratio on the growth behavior near trenches has been revealed. Although the growth rate on trench sidewalls is usually lower than that on the bottom of a trench and that on the top surface, this difference in epilayer thickness becomes smaller with decreasing C/Si ratio during growth. The use of a low C/Si ratio is effective in filling trenches. A smooth morphology was obtained on SiC substrates inclined toward the [112̄0] direction, but triangular surface defects appeared on SiC substrates inclined toward the [11̄00] direction.
Influence of Hydrogen Plasma Treatment and Post-Annealing on Defects in 4H-SiC
Authors: Um Myung Yoon , Jeon In Sang , Eom Da Il , Kim Hyeong Joon
Published: February 2005

In this work, we have investigated the influence of hydrogen plasma treatment on defects in 4H-SiC. Hydrogen was incorporated in 4H-SiC single crystals by plasma treatment, and its effects were characterized by current–voltage measurements and deep-level transient spectroscopy. The reverse leakage current level reduction and the Schottky barrier height increase after hydrogen plasma treatment could be explained by Fermi level (FL) pinning and interface states passivation. Plasma-induced defects were formed by the bombardment of energetic particles on the crystal lattice, but they were annealed out at low annealing temperatures of 400–500°C. Considering the annealing temperature, it can be concluded that these defect levels are related to the carbon vacancy defects. It was also revealed by I–V measurement that the hydrogen passivation of defects was maintained up to 500°C.
Investigation of A 450 V Rating Silicon-On-Insulator Lateral-Double-Diffused-Metal–Oxide– Semiconductor Fabrication by 12/25/5/40 V Bipolar-Complementary Metal–Oxide–Semiconductor Double-Diffused Metal–Oxide–Semiconductor Process on Bulk Silicon Substrate
Authors: Chang Fang-Long , Lin Ming-Jang , Liaw C. W. , Liao Ta-Chuan , Cheng Huang-Chung
Published: February 2005

In this study, traditional bipolar-complementary metal oxide semiconductor (CMOS)-double diffused metal oxide semiconductor (DMOS) (BCD) technology, which is designed for only lateral bipolar (Bipolar, 12 V BVCEO and 25 V BVCBO), complementary metal oxide semiconductor (CMOS, 1.2 V threshold voltage) and double diffused metal oxide semiconductor (DMOS, 40 V breakdown voltage) transistors on the bulk silicon wafer, has been successfully utilized directly in silicon on insulator lateral double diffused metal oxide semiconductor (SOI LDMOS) for the first time without changing any trial parameters. To simultaneously display the characteristics of high-power, high-speed and high-frequency, the results of output characteristics, switch and microwave performance must be moderate instead of optimum. In addition, according to the experimental results, it is proved that Bulk-BCD technology simultaneously enables high-speed, high-frequency and high-blocking-voltage applications–such as those in high-voltage integrated circuit switches (ns-range) and RF power amplifiers (MHz range to GHz range)–using a SOI wafer.
Investigation of PtNb Alloy Electrodes for Ferroelectric Pb(Zr,Ti)O3 Thin Film Capacitors
Authors: Kurita Masaaki , Okamura Soichiro , Shiosaki Tadashi
Published: February 2005

PtNb alloy thin films with Nb content of 4.5 mass% and Pt films were fabricated on SiO2/Si substrates by DC magnetron sputtering and their thermal stability was investigated. The resistivity of as-deposited PtNb films was approximately 40 µΩcm and gradually decreased to 30 µΩcm with an increasing of the annealing temperature. These values were double that of the resistivity of Pt films, but lower than the resistivity of conventional oxide electrodes. The surface morphology of PtNb films did not change at any annealing temperature below 650°C while the recrystallization and the grain growth were observed in Pt films above 550°C. The Pb(Zr,Ti)O3 (PZT) thin films formed on PtNb electrodes by the chemical solution deposition (CSD) method at 650°C consisted of large plate-like crystals, while the PZT thin films on Pt electrodes had a cluster-like structure which consisted of small grains and pores. The endurance property of PZT capacitors was significantly improved by using PtNb electrodes.
Epitaxial Growth of Semiconducting BaSi2 Thin Films on Si(111) Substrates by Reactive Deposition Epitaxy
Authors: Inomata Yuya , Nakamura Tomoyuki , Suemasu Takashi , Hasegawa Fumio
Published: February 2005

The optimum growth temperature is determined for the epitaxial growth of semiconducting orthorhombic BaSi2 films on Si(111) substrates by reactive deposition epitaxy (RDE). X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED) analyses confirmed that smooth, [100]-oriented epitaxial BaSi2 films could be obtained by RDE at a substrate temperature of 600–650°C when the Ba deposition rate was 10 nm/min.
Temperature Dependence of Shallow-Trench-Isolation Mechanical Stress on n-Channel Metal–Oxide–Semiconductor Field-Effect Transistors
Authors: Lai Jinn-Horng , Gong Jeng , Liao Tsuoe-Hsiang , Chen David Cheng-Hsiung
Published: February 2005

The impact of shallow-trench-isolation (STI) induced mechanical stress on a device's performance has been studied in many research works. However, there has been a lack of study concerning its temperature dependence. This paper deals with the influence of temperature on the drive current degradation in modern n-channel metal–oxide–semiconductor field-effect transistors (n-MOSFETs) that is caused by STI-induced mechanical stress. The results show that as the operating temperature increases, the drive current degradation induced by STI mechanical stress is slightly reduced. A simple equation is presented for the purpose of quantitative analysis.
Magnetic Domain Imaging of Ni Micro Ring and Micro Dot array by Photoelectron Emission Microscopy
Authors: Okuda Taichi , Kiwata Hideyuki , Matsushima Takeshi , Wakita Takanori , Harasawa Ayumi , Ono Kanta , Kihara Takayuki , Oshima Masaharu , Yokoo Atsushi , Kinoshita Toyohiko
Published: February 2005

The magnetic domain structures of Ni micro ring (the inner and outer diameters are changed in a micrometer region) and micro dot array with different shapes and with a small separation between dots were observed by the combined method of photoelectron emission microscopy and X-ray magnetic circular dichroism. For the micro rings with a large inner diameter, a flux-closure (FC) domain structure tends to appear more easily than for those with a small inner diameter. This means that the FC domain structure of the micro rings with a large inner diameter is energetically more stable than those of the micro rings with a small inner diameter and the disks. After applying an external pulsed magnetic field of about 40 mT in the in-plane direction, each domain structure switched to an almost perfect single-domain structure. Because of the absence of a central vortex core in the ring as compared with the disks, exchange energy decreases substantially. These phenomena are discussed along with the simulation results. For the micro dot array, the interaction between dots was directly observed. Particularly for the circular disks with a small diameter showing FC domains, no interaction is observed due to the lack of stray fields from each disk. On the other hand, dots with multi domain structures interacted. These types of information may provide us fundamental knowledge for designing high-density magnetic recording media.
Walk-Off Compensated UV generation in Lithium Tetraborate crystals
Authors: Chatterjee Udit , Gangopadhyay Sudipta , Ghosh Chittaranjan , Chattopadhyay Pradip Kumar , Bhar Gopal Chandra
Published: February 2005

As high as 21 mJ of energy at 288.5 nm is produced for the first time in Lithium Tetraborate crystals utilizing Type-I twin crystal walk-off compensated second harmonic generation. In the process it is shown that unless one uses the walk-off compensated configuration, the effect of walk-off degrades the conversion efficiency of the second harmonic generation even when the so-called aperture length is much greater than the actual length of the crystal as well as the crystal has an appreciably low value of walk-off angle.
Broadband Light Source Based on Stimulated Raman Scattering in Silica Optical Fiber for Optical Coherence Tomography
Authors: Higashihata Mitsuhiro , Nakamura Tadashi , Takahashi Akihiko , Nakata Yoshiki , Okada Tatsuo
Published: February 2005

A spatially coherent and temporally incoherent light source has been developed by stimulated Raman scattering in a single-mode optical fiber pumped by a conventional nano second solid-state laser. A broadband light with a bandwidth of roughly 400 nm was obtained using a 500-m-long single-mode SiO2 optical fiber at a pump energy of 0.6 mJ. When a white-light Michelson interferometer was constructed using the fiber Raman light source, the longitudinal spatial resolution of 1.8 µm was achieved.
Run-Length-Limited (4, 13) Code for High Density Optical Storage Systems
Authors: Yang Xin , Gong Mali , Huang Lei , Zhang Haitao
Published: February 2005

In this paper, we propose a new (4, 13) run-length-limited (RLL) code for high-density optical storage systems. The code rate of this code is 1/3, and the resulting density ratio is 1.67, which is larger than that of EFMPlus code used for digital versatile disc (DVD) systems. The bit error rate (BER) performance of the code is analyzed considering noise and channel jitter. The (4, 13) RLL code has very low complexity of hardware since the mapping rule is simple. The encoding and decoding circuits of the code are implemented using a complex programmable logic device (CPLD) chip.
Observation of Eye Pattern on Super-Resolution Near-Field Structure Disk with Write-Strategy Technique
Authors: Fuji Hiroshi , Kikukawa Takashi , Tominaga Junji
Published: February 2005

Pit-edge recording at a density of 150 nm pits and spaces is carried out on a super-resolution near-field structure (super-RENS) disk with a platinum oxide layer. Pits are recorded and read using a 635-nm-wavelength laser and an objective lens with a 0.6 numerical aperture. We arrange laser pulses to correctly record the pits on the disk by a write-strategy technique. The laser-pulse figure includes a unit time of 0.25 T and intensities of P
w1, P
w2 and P
w3. After recording pits of various lengths, the observation of an eye pattern is achieved despite a pit smaller than the resolution limit. Furthermore, the eye pattern maintains its shape even though other pits fill the adjacent tracks at a track density of 600 nm. The disk can be used as a pit-edge recording system through a write-strategy technique.
Over 31 nm Wavelength-Switched Pulse Generation From a Fiber Ring Laser with a Fabry–Perot Laser Diode
Authors: Peng Peng-Chun , Chi Sien
Published: February 2005

An actively mode-locked fiber ring laser for generating wavelength-switched optical pulses is demonstrated in this paper. A Fabry–Perot laser diode (FP-LD) is used as a modulator, and a tunable filter is used as a wavelength selector. At a fixed modulation frequency, the optical side-mode-suppression-ratio (SMSR) of this fiber laser is better than 40 dB over the wavelength-switched range of 31 nm. The pulsewidth is between 41.72 ps and 44.74 ps.
Ablation of Silicone Rubber Using UV-Nanosecond and IR-Femtosecond Lasers
Authors: Fukami Yuko , Okoshi Masayuki , Inoue Narumi
Published: February 2005

Silicone rubber was ablated by an ArF laser, the forth harmonics of Nd:YAG, and a Ti:sapphire laser for microdrilling. The fs-Ti:sapphire laser ablated the sample at a rate higher than those of the other lasers, in the fluence range of approximately 0.15–2.0 J/cm2. No chemical denaturation was observed after irradiation using each laser. The UV-ArF laser ablated the irradiated area precisely, making the surface flat and smooth.
Efficiency Improvement of Cu(InGa)Se2 Thin Film Solar Cells with a High Ga Composition Using Rapid Thermal Annealing
Authors: Miyazaki Hisashi , Mikami Rui , Yamada Akira , Konagai Makoto
Published: February 2005

Cu(InGa)Se2 (CIGS) thin films were grown by three-stage growth process using a molecular beam deposition system on a Mo/soda lime glass (SLG) substrate. The raman scattering spectroscopy of as-grown samples with a high Ga composition showed the presence of Cu2-x
Se compounds, which are thought to be responsible for the degradation of the open circuit voltage of solar cells. Rapid thermal annealing (RTA) using an infrared lamp in forming gas (N2 95% + H2 5%) ambient under atmospheric pressure was examined in order to remove the Cu2-x
Se compounds, and it was found that hydrogen is necessary to remove the Cu2-x
Se compounds. The influence of RTA conditions on device performance was investigated. A Cu(In0.4Ga0.6)Se2 (energy band gap: E
g=1.37 eV) solar cell with an efficiency of 11.7%, particularly open circuit voltage (V
oc) increased from 640 to 750 mV, was obtained by RTA at 400°C.
Pixel-Isolated Liquid Crystal Mode for Flexible Display Applications
Authors: Jung Jong-Wook , Park Seo-Kyu , Kwon Soon-Bum , Kim Jae-Hoon
Published: February 2005

We developed a new device using anisotropic phase separation from liquid crystals (LCs) and polymer composite materials using UV intensity variation and polymer wetting properties for flexible display applications. In the device, LC molecules are isolated in pixels where LCs are surrounded by interpixel vertical polymer walls and horizontal polymer films on the upper substrate. This device shows very good mechanical stability against external pressure. The electro-optic characteristics and the mechanical stability of the device are discussed in view of flexible display applications.
3-Dimensional Ion Transport in Liquid Crystals
Authors: Vermael Stefaan , Stojmenovik Goran , Neyts Kristiaan , Boer Dick de , Fernandez F. Anibal , Day Sally E. , James Richard W.
Published: February 2005

One-dimensional ion transport has been studied in the past decade because of the importance of image retention and voltage holding ratio. Ions inside a liquid crystal (LC) disturb the expected optical behavior of LC molecules when the applied voltage is higher than the LC threshold. In LC devices with complex electrode patterns, interesting ionic effects occur. Advanced and reliable simulation programs are a necessary to investigate this. This paper describes the theory and results of a Monte Carlo 3D ion transport simulation program for LC devices.
Dielectric Relaxation Behavior and Thickness Dependent Phase Transition of a Ferroelectric Liquid Crystal
Authors: Kundu Shyamal Kumar , Suzuki K. , Chaudhuri B. K.
Published: February 2005

Dielectric relaxation behavior of a ferroelectric liquid crystal (Felix-15/100) showing SmC*–SmA phase transition have been reported. Thickness dependent dielectric constant measured by varying the cell thickness (∼6, 11, 18, 36, 59 and 79 µm) showed increase of dielectric constant and the ferroelectric transition (Curie temperature T
C) with increase of cell thickness. The observed non-linear variation of T
C as a function of thickness is better described by an empirical formula of the form T

x
=T
C-γd
-β (where β and γ are sample dependent parameters). Since d is related to the domain width, different values of β and γ are related to the domain width and hence with the dipolar ordering. Different values of the sample dependent parameters β and γ may, therefore, be considered as a measure of molecular ordering (depending on molecular interaction) which causes the change of T
C with thickness. It is thus concluded that the values of β and γ should be related to the dipolar interaction in the ferroelectric system under consideration.
Investigation of Dielectric Properties of BaZr(BO3)2 Ceramics
Authors: Lee Ying-Chieh , Lee Wen-Hsi , Hu Ching-Li , Shieu Fuh-Sheng
Published: February 2005

The effects of 3Zn-B2O3, B2O3 and flux additions on the microwave dielectric properties and the microstructures of Ba2Ti9O20-based ceramics have been investigated in our previous study. BaZr(BO3)2 phase existed in the Ba2Ti9O20-based ceramics, and could affect the microwave dielectric properties when the formation of the BaZr(BO3)2 phase is enhanced. In order to understand well the effect of the BaZr(BO3)2 phase on the dielectric properties of Ba2Ti9O20-based ceramics, the BaZr(BO3)2 composition was synthesized by conventional solid-state methods from individual BaCO3, ZrO2 and B2O3 powders. X-ray diffraction (XRD) results show the presence of the mainly crystalline phase, BaZr(BO3)2, and the minor phases are BaZrO3 and ZrO2 in the sintered ceramics. Scanning electron microscopy images show that the BaZr(BO3)2 grain prefers to develop oriented dendrite microstructures. Plots of dielectric loss versus sintering temperatures show a linearity, and ranges from 0.85 (at 1080°C) to 0.08 (at 1250°C). However, the dielectric constant does not increase with increasing sintering temperature, and it's value is maintained at 11–13.
Surface Azimuthal Anchoring Energy between the Grating Surface and Nematic Liquid Crystal Layer Studied by Finite Element Method
Authors: Ohta Yasuyuki , Tanaka Norihiko , Kimura Munehiro , Akahane Tadashi
Published: February 2005

It has been pointed out that Berreman's topological alignment model is applicable to a fairly shallow grating surface, but not for gratings with deep groove profiles. The reason for Berreman's model breakdown was presumed to be the absence of a second derivative in the algebra of elastic theory. In this paper, the saturation tendency of surface azimuthal anchoring energy as a function of the grating height as decribed by numerical simulation on the basis of finite element method (FEM). A good agreement between FEM and experimental results was also demonstrated.
Interdiffused Layers in Antiferromagnetically Coupled Fe/Si Multilayers Studied by Soft-X-Ray Fluorescence Spectroscopy
Authors: Imazono Takashi , Hirayama Yushi , Ichikura Shigeru , Kitakami Osamu , Yanagihara Mihiro , Watanabe Makoto
Published: February 2005

We measured the Si L
2,3 fluorescence spectrum of an antiferromagnetically coupled Fe (3.0 nm)/Si (1.3 nm) multilayer using undulator synchrotron radiation. We estimated the chemical composition and thickness of Fe silicide layers formed by interdiffusion by curve fitting analysis using the fluorescence spectra of amorphous Fe silicides. We clarified that the amorphous Si layer of 1.3 nm thickness changed in its middle region into amorphous FeSi2 of 0.7 nm thickness, which plays an important role in the strong antiferromagnetic exchange coupling in the Fe/Si multilayer. It was also confirmed that soft-X-ray fluorescence spectroscopy has a high potential for analyzing buried interfaces nondestructively.
Epitaxial Growth of Copper and Cobalt Phthalocyanines on KCl
Authors: Hoshino Akitaka , Takenaka Yoshiko , Izukashi Masahiro , Yoshida Hidehito , Miyaji Hideki
Published: February 2005

The crystal structures and epitaxial orientations of copper and cobalt phthalocyanines on a KCl (001) surface are investigated by transmission electron diffraction. Both the epitaxial crystals are found to have a parallel molecular arrangement with α(+)-type molecular stacking along their molecular columns and have essentially the same epitaxial orientations. On the basis of these structures, two kinds of epitaxial orientations are investigated. One, the primary orientation, is well explained by point-on-line coincidence at the interface. The other secondary orientation, which is slightly rotated from the primary orientation, does not show any exact coincidence at the interface. Adsorption energy calculations show that the most stable molecular orientation on the substrate nearly coincides with the molecular orientations observed in the epitaxial crystals. In addition to this, one of the two-dimensional axes of the epitaxial crystals at the interface nearly coincides with one of the substrate surface lattice vectors. On the basis of these findings, how the epitaxial orientations are determined during the crystal growth is discussed.
Effects of Sputtered High-Energy Particles on the Structure and Photocatalytic Performance of TiO2 Films Prepared by a DC Reactive Sputtering Method
Authors: Noguchi Daisuke , Kawamata Yoshio , Nagatomo Takao
Published: February 2005

By using the Kevin–Meyer formula, we calculated the energy of the high-energy particles (recoil argon ions and negative oxygen ions) that are unique to sputtered thin-film formation when they arrived at a substrate during the sputtering process. We found that the energy of the high-energy particles arriving at the substrate decrease if total gas pressure increases, whereas the photocatalytic performance of a TiO2 film increases if the total gas pressure increases. We also found that as total gas pressure increases, the surface morphology changed from a gap-free structure to a porous structure in which subgrains were observed. Accordingly, the average surface roughness (R
a) and surface area (S) of the thin film increased. The number of defects, mainly oxygen defects, in the forbidden band also changed depending on the energy of the high-energy particles. Therefore, it was found that the high-energy particles affect the surface area of the TiO2 thin films and the formation of defects in the thin films, which consequently influences the photocatalytic performance.
Dependence of Tip Depth of Silicon Needles on Fabrication Process Conditions
Authors: Kanechika Masakazu , Mitsushima Yasuichi
Published: February 2005

We previously developed a process for fabricating needle-shaped silicons (silicon needles) with a small tip radius and a high aspect ratio. They can be obtained by highly selective anisotropic dry etching, using the oxygen precipitation, that is, the SiO
x
clusters in the silicon substrate, as etching masks. The SiO
x
clusters can be generated by nitrogen ion implantation and the subsequent oxidation. In this article, we show the dependence of the tip depth of silicon needles on the fabrication process conditions. From experiments, it was found that the tip depth does not depend on the acceleration energy of the nitrogen ions. Instead, it depends on the temperature of the subsequent oxidation and the deposition rate of the sidewall passivation film which is produced during the dry etching to protect the silicon needles from being side-etched. The reason for the dependences will be discussed.
High Ozone Generation with a High-Dielectric-Constant Material
Authors: Toyofuku Masaharu , Ohtsu Yasunori , Fujita Hiroharu
Published: February 2005

An optimum-dielectric-constant material with a fixed size was experimentally obtained for high ozone generation in a parallel-plate barrier discharge. The ozone production rate as a function of dielectric constant was found to depend strongly on discharge voltage. The ozone production rate for strontium titanium oxide (SrTiO3) with high dielectric constant of approximately 300 was the highest among various existing dielectric materials under low discharge voltage (root-mean-square value) of 1.2 kV, while for titanium oxide (TiO2) with dielectric constant of about 100, the highest ozone production efficiency was obtained at a wide range of discharge power and/or ozone concentration.
An Analogue–Digital Instrumentation System for Characterizing Electrical Behavior of Antiferroelectric Liquid Crystal Display Pixels
Authors: Pena José M. Sánchez , Santos José Isidro , Pérez Isabel , Vázquez Carmen , Gonzalo Ana Belén
Published: February 2005

A cost-effective A/D electronic system based on the simplified structure Σ–Δ is presented. This system can reproduce the external voltage applied to a nonlinear capacitor and derive the electric current across it. Moreover, polarization vs applied voltage curves can also be measured by integrating electric current in real time. The application of this system to the evaluation of liquid crystal display pixels is demonstrated.