Table of contents

By means of deep level transient spectroscopy (DLTS), the diffusion profiles of substitutional nickel atoms in silicon are investigated in dislocation-free silicon at 980°C for the in-diffusion process and at 950°C for the annealing process. The results are analyzed on the basis of the dissociative mechanisms of diffusion. It is shown that nickel distribution in dislocation-free silicon can be explained by the dissociative mechanism with the model that sinks and sources of vacancies are present in the bulk in addition to the surfaces.

The chemical mechanical polishing (CMP) process is widely used for the global planarization of the inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD layer and ILD become thinner, defects such as micro-scratches can lead to severe circuit failure, which affects yield. In this study, for the improvement of the CMP process, de-ionized water (DIW) pressure was varied, purified nitrogen (PN₂) gas was used, and a point of use (POU) slurry filter and high spray bar (HSB) were installed. Our experimental results show that DIW pressure and PN₂ gas factors were not related to removal rate, but the edge hot spot of the patterned wafer had a marked effect. Also, the filter installation in the CMP polisher could remarkably reduce the number of defects after CMP processing, thus it is shown that the slurry filter plays an important role in determining pad lifetime. However, the slurry filter cannot eliminate defect-causing particles completely. Thus, we suggest that it is necessary to install a high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak points of a slurry filter.

The reliability of low-temperature-processed (≦425°C) polycrystalline-silicon thin film transistors (poly-Si TFTs) was investigated. For n-channel TFTs, the sub-threshold characteristics shifted in the positive direction when a high voltage stress was applied to them, which is particularly significant in small-size TFTs as well as in wide-channel TFTs. It was verified that the temperature of the TFTs reached over 300°C due to self-heating when this stress was applied. We estimate that the breaking of Si–H bonds and re-generation of dangling bonds in the channel poly-Si layers due to self-heating are responsible for the degradation phenomenon.

Conventional transmission electron microscopy was applied to study the nature of crystallographic defects under some types of surface morphological faults formed on a 4H–SiC film homoepitaxially grown on a (0001) off-cut substrate. "Wavy pit" faults consist of arrays of small surface cavities and half-loops of perfect dislocations expanding towards the direction of their Burgers vector. "Carrot" and "comet" faults are accompanied by stacking faults. The geometry of crystallographic defects under surface faults is closely related to the off-cut direction of the substrate. Formation mechanisms of surface faults are discussed.

An amorphous-like tungsten silicide film, deposited by chemical vapor deposition at a higher flow ratio of 2.5 of WF₆/SiH₄, was used as the barrier layer in the copper gate electrode. This film processes superior barrier characteristics to those of the typical tungsten film at a lower flow ratio of 0.4 of WF₆/SiH₄ because it lacks the fast diffusion paths of columnar grain boundaries. We proved that the film successfully suppressed copper atom diffusion toward the gate oxide during annealing at 600°C for 30 min. We also found that the amorphous-like tungsten silicide film exhibits better barrier characteristics after in-situ nitrogen plasma treatment at 300°C for 5 min.

This paper presents the 4.5 kV trench gate injection enhanced gate transistor (IEGT) with a current sense function that realizes short-circuit withstanding capability without suffering from low on-state voltage drop. We propose a new concept of the press pack IEGT with the current sense function. In the press pack IEGT with the current sense function, 20 IEGT chips are connected in parallel inside the package, and its collector current can be controlled under short-circuit condition.

The quantum-mechanical effects in counter doped n-channel metal–oxide–silicon field-effect transistors (MOSFETs) for metal gate complementary metal–oxide–silicon (CMOS) have been simulated using self-consistent calculations. The energy levels and fractional occupation of subbands, gate tunneling current and channel mobility in such metal gate MOSFETs have been investigated, comparing with those in n⁺-poly Si gate MOSFETs. The energy levels and fractional occupation for metal gate MOSFETs are fairly different from those for poly Si gate MOSFETs since the accumulation and inversion layers are formed on the respective surfaces by positive gate voltages. The tunneling current in metal gate MOSFETs is smaller than that in poly Si gate MOSFETs. In particular, at the gate voltages below 1 V, the current density is reduced by one order or above of magnitude. Moreover, the mobility in metal gate MOSFETs with lightly counter doped channel becomes much larger than that in poly Si gate MOSFETs because of the large suppression of ionized impurity scattering and surface roughness scattering.

The main purpose of this study was to regenerate the used oxide slurry using filters. The solid content in regenerated slurry was controlled by ultra fine (UF) filtration that extracts only the solution from diluted slurry. Reverse osmosis (RO) filtration was adapted to recover chemicals added in the original slurry formulation by rejecting pure deionized (DI) water from slurry solutions collected by UF filtration. The specific gravity, conductivity, and pH were adjusted by the filtration and addition of KOH in the regenerated slurry. The new slurry was intentionally added into the regenerated slurry to reduce the process time and increase the lifetime of used slurry. The same removal rate of tefraethylorthosilicate (TEOS) oxide was observed when chemical mechanical planarization (CMP) was performed using the regenerated oxide slurry. The particles size of the regenerated slurry was smaller than that of the original slurry. No microscratches were observed in the wafer polished by the regenerated slurry. Also, the defect densities of polished oxides were decreased after polishing with the regenerated slurry.

Adding high molecular-weight polyethylene glycol (PEG) as a carrying agent benefits Cu electroplating from the viewpoint of an increase in both filling capability and films' conductivity, when plated in a lower current-density region. On electroplating in a higher current-density region, a gradually decreasing grain size from the top to bottom of Cu films occurs in the electrolyte without PEG or with PEG200. In comparison, sharp grains are formed for the mentioned multi-domain crystallization for those films deposited by the electrolyte containing PEG2000 or PEG6000 due to its lower surface tension which facilitates grain growth along the higher electric field. The used concentration of PEG was flexible due to the fact that the surface morphology, resistivity and deposition rate of deposited films remained almost unchanged over a wide PEG concentration range.

A bottom antireflective coating (BARC) is essential for deep ultraviolet lithography. We have already reported the BARC composed of polysilanes which can be spin coated and etched faster than resists. In this study, polysilane structures are optimized in order to set the etch selectivity against resists to a higher level than that previously reported without losing the antireflection performance. The results indicate that the networked polysilanes structure is the most suitable. Poly(methylhydrosilane) whose Si–H is partially cross-linked and has the highest silicon content of 64.8 wt% yields the optimal results. The resist profile is achieved on it without footing and residue. The refractive index at the wavelength of KrF excimer (248 nm) is n=1.93, k=0.32, and the polymer reduces multi-reflection in both resists and in transparent substrates. The etch selectivities are 4.8 under Cl₂ plasma and 6.6 under HBr plasma, which are much higher than that of an organic BARC, namely, about 1.

A metal-induced crystallization method can be used to decrease the crystallization temperature of amorphous silicon (a-Si). In this study, Pd metal was deposited by an electroless plating method. After it was annealed at 550°C, two kinds of needlelike grains were found. The direction of the primary grain was along <211> and the growth of the secondary grain occurred along the <011> direction.

The anisotropy field of 2K/M_s=-16.71 kOe and the g-factor of g=2.14 of lanthanum-doped calcium hexaboride (Ca_0.995La_0.005B₆) are determined from the analysis of the ferromagnetic resonance data reported by Kunii [Butsuri 55 (2000) 947].

The second harmonic generation signal converted from the fundamental wavelength of 22 µm of a free electron laser was observed for the first time using a birefringent Te crystal. The experimental conversion efficiency of Te crystal for second harmonic generation is 0.53%, which is equivalent to the theoretical value within a factor of 2. The Te crystal has been incorporated into an autocorrelator system to measure the micro-pulse width of infrared free electron laser successfully.

We fabricated a GaInAsP microdisk laser using a benzocyclobutene (BCB) polymer cladding, which decreased the fragility and the thermal resistance of the conventional air cladding device and simplified the current injection using the metal pad electrode. The threshold current for a 7-µm-diameter device was 0.4 mA at room temperature, which was almost the same as that for the air cladding device. The red shift of the resonant spectrum against the continuous wave current was reduced by 54% in the BCB cladding device. Nearly 90% of this reduction is attributed to the reduction in thermal resistance. The remaining 10% is due to the reduction in temperature dependence (athermal effect) by the BCB cladding which has a negative temperature dependence of the refractive index. An analysis shows that the microdisk laser with a polymer cladding can function as an athermal laser when the disk thickness is reduced to 50–80 nm.

A compact distributed-feedback (DFB) dye laser with a plastic waveguide was developed. The DFB operation was attained by the interference of two pumping beams from a frequency-doubled pulsed Nd:YAG laser, and a wavelength range between 560 nm and 994 nm was continuously covered. The dye chip can instantaneously exchanged in any spectrum region. The threshold energy was decreased to the order of 100 µJ with the waveguide configuration. The maximum life of the dye chip was 10⁶ shots.

We studied the refractive behavior of two-dimensional (2D) photonic crystals consisting of rods with a rectangular cross section. All crystals treated in this work are assumed to have the same lattice constant. By modifying only the rod's side ratio, we found that negative or positive anisotropic refractive behavior or a photonic band gap can be observed. This behavior is confirmed by using a rigorous electromagnetic theory, namely, the finite-difference time-domain (FDTD) method. By taking advantage of this behavior, we furthermore combined crystals with different properties, and showed that the smooth conjunction produced by the same lattice constant allows each part of the combined crystal to keep its refractive property as if each part were treated individually.

The tolerance of the optical components in the near-field recording (NFR) system is analyzed. The system uses a solid immersion lens (SIL) for near-field recording and an air bearing slider to maintain the near-field gap between the SIL and a magneto-optic (MO) disk. From the analysis, it is found that some of the components have a sub-micrometer level tolerance, which is unsuitable for practical application. To loosen this tight tolerance, the position of the collimator lens (CL) is adjusted according to the assembly state. The state of the assembly is detected in real time from the intensity-profile signal that is generated through a developed technique. Therefore, by monitoring the signal carries out the adjustment of the CL. The performance of the technique is evaluated through numerical calculation and the experiment is carried out in the developed NFR system.

We propose and experimentally prove a new signal detection method for optical disc systems, named "modified correct far-field (MCFF)", which realizes a stable servo control to various digital versatile discs (DVDs) with different groove specifications with using one photo detector.

The refractive index of polyimide can be changed by irradiation with ultraviolet light. The amount of change in refractive index is >10^-3. The Kramers–Kronig model can explain the mechanism. Utilizing this phenomenon, Bragg gratings can be fabricated in a polyimide waveguide by irradiation with an ultraviolet laser beam. It has a possibility of application in tunable wavelength filters because polyimide has a birefringent characteristic and a large thermooptical constant.

The triggering ability of the laser-triggered lightning method is improved by using a KrF excimer laser with a high-repetition-rate of kHz order. The density of a weakly ionized plasma channel is enhanced by the accumulation effect of charged particles generated by the high-repetition-rate laser. The accumulation effect of charged particles and the enhanced triggered discharge were confirmed in the case of a laser repetition rate of 1 kHz.

We describe a new type of beam profile monitor developed for measurements of an electron beam as small as 10 µm in size. This monitor is based on the Compton scattering of electrons with a laser light target. A thin and intense laser beam (laser wire) is produced by injecting a CW laser beam into a Fabry–Perot optical cavity. We were able to obtain a stable laser wire having a beam waist of 14.52±0.55 µm and a power gain of 220±20. This monitor was installed in the ATF damping ring at KEK, and was used to measure its vertical emittance. We report in this paper the development and performance studies of this monitor in detail.

We have designed broad-band normal-incidence antireflection coatings over the visible spectral region for a set of eight various substrates with indices 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75 and 1.784. It is shown that the calculated average reflectance of the eighty-layer flip–flop antireflection coating design for substrates over the 400–750 nm spectral region can be reduced to less than 0.34%, which is acceptable.

Unique techniques to study laser ablation at low cost have been devised and developed to monitor laser processing. The methods of time-resolved spatial distribution, a surface observation technique performed on-line during the laser irradiation, and induced current detection associated with the fast electron propelled from the target are presented.

SiO_x thin films were prepared by thermal evaporation of SiO powder in vacuum onto Si substrates. The as-deposited samples exhibited blue emission under UV irradiation. Post-annealing was carried out in vacuum, and the photoluminescence (PL) spectra were redshifted from the visible to near-infrared range as the annealing temperature increases. It was also found that the main PL peak wavelength was affected by the deposition rate. The PL spectra of the films consisted of a red and a blue PL. Annealing treatments in oxygen atmosphere were also carried out to investigate the effect of oxidation. From the analysis of the results of infrared spectrometry, we attributed the blue emission to oxygen vacancies in SiO_x. And the red PL could be explained by the quantum confinement effect in Si clusters embedded in the SiO_x matrix.

Microcrystalline silicon (µc-Si) films and solar cells were prepared by mercury-sensitized photochemical vapor deposition (photo-CVD). The changes in the structural properties of a series of µc-Si films grown under various H₂ dilution and deposition pressure conditions were discussed. The results indicated that the properties of µc-Si films depend strongly on the atomic hydrogen. The microstructures of µc-Si films on textured SnO₂ with different haze factors (from 13% to 65%) were observed with a scanning electron microscope and a transmission electron microscope. The observations revealed that the µc-Si layers grew from the initial stage of deposition with columnar grains and that they were conformal to the surface of textured SnO₂. The grain boundary density of µc-Si film on SnO₂ with higher haze factors was lower than that on SnO₂ with lower haze factors. The effect of textured SnO₂ with different haze ratios on p–i–n µc-Si cell characteristics was discussed and it was found that the higher haze factors showed a higher degree of light trapping in our µc-Si cells. We deposited µc-Si cells with an intrinsic µc-Si layer thickness of 430 nm on a textured SnO₂ sample with a haze factor of 42% and achieved a conversion efficiency of 6.55%.

We investigated the optoelectronic properties of orientation-controlled lead phthalocyanine (PbPc) films on (0001) sapphire and (001) KCl substrates prepared by vacuum deposition. The results obtained from X-ray diffraction measurements indicate that the orientations of the molecular planes in the PbPc films on the sapphire and KCl substrates are perpendicular and parallel to the substrate surface, respectively. It is found from current–voltage characteristics under dark and illumination conditions that the in-plane conductivity of the PbPc film on the sapphire substrate is about 20 times as large as that on the KCl substrate. This finding indicates that the in-plane conductivity is dominated by the molecular-plane orientation, which is considered to be due to their one-dimensional conduction nature via Pb ions. Furthermore, we discuss the contribution of excitons to the photocarriers based on the results of the absorption and photocurrent spectra.

The geometrical and electronic structures of β-FeSi_1.875X_0.125 (X = B, N, Al or P) were investigated using first principles pseudopotential calculations based on generalized gradient approximation (GGA) density function theory. The calculated structural parameters depend strongly on the kinds of dopants and sites. The total energy calculations for substitution of dopants at the Si_I and the Si_II sites revealed that Al and P prefer the Si_I sites, whereas B and N prefer the Si_II sites. The calculations predict that β-FeSi_1.875B_0.125 and β-FeSi_1.875Al_0.125 show p-type conduction, while β-FeSi_1.875P_0.125 shows n-type. The prediction of the carrier type of β-FeSi_1.875B_0.125 does not agree with the experimental results. The experimental results are theoretically interpreted on the assumption that B atoms are located not at the Si sites but at the Fe_I sites in B-doped β-FeSi₂.

The electrical and thermal transport properties are characterized for layer-structured (ZnO)_mIn₂O₃ (m=5 and 9) (Z_mIO) ceramics of near theoretical densities. The results of the low temperature Hall effect study suggested that the InO₂^- layers, which have oxygen defects, determine the carrier scattering mechanism of the material, and explain the previously demonstrated two-dimensional character of the carrier transport behavior. From an adaptation of the Wiedemann–Franz law, the lattice thermal conductivity (κ_L) of Z_mIOs at 300 K is estimated to be ∼2.6 W/mK; this value is nearly one fifteenth of that for Al-doped ZnO ceramics (∼40 W/mK). These results suggest that the two-dimensional structure consisting of the InZn_mO_m+1⁺ and InO₂^- sub-lattices gives rise to the strong electrical anisotropy and the low κ_L which is attributed to the reduced mean free path of the phonon, similar to artificial super-lattice materials.

Electrical conductivities of nanoscale periodic porous graphites are theoretically determined using the Boltzmann equation. The conductivities of nanoscale periodic porous graphites markedly differ from that of conventional graphite, that is, they become maximum and decrease as the Fermi energies increase although the conductivity of conventional graphite increases, which causes the phenomenon analogical to Gun's effect in the field of semiconductors. This is because the nanoscale periodic porous graphites possess complex electronic band structures. Moreover, velocities of semimetallic nanoscale periodic porous graphites are lower than that of conventional graphite although their electronic properties judged from the band gaps are the same, that is, semimetallic. Those conductivities of nanoscale periodic porous graphites may be affected by their topology. The electronic transport properties in high and low dopings or energies are clarified.

The protonic conduction of Sc-doped SrZrO₃ (SrZr_1-xSc_xO₃) in the single crystal form is investigated. The SrZr_1-xSc_xO₃ crystals exhibit significantly higher conductivity than the pure ones, and the crystal with x=0.05 exhibits the highest conductivity of those masured. The activation energy of the SrZr_1-xSc_xO₃ crystal decreases rapidly with increasing Sc³⁺ concentration when x≤0.05, and increases when x>0.05. The activation energy of SrZr_0.95Sc_0.05O₃ agrees with the energy separation between hole states at the top of the valence band and the Fermi level.

In this paper, we present the results of a study conducted on a semiconductor coupled surface acoustic wave (SAW) programmable correlator, in which the propagating SAW on a highly coupling coefficient piezoelectric substrate, couples with a bonded semiconductor diode bridge through multi-strips. We propose a novel programmable correlator with a Schottky diode structure. It shows high efficiency and robustness against parameter variations including temperature variation of delay. We discussed the basic requirements of nonlinear capacitance characteristics of the diode for parallel and series circuits. We estimated the basic performance of the device using circuit simulation and fabricated a test device using an epitaxial lift off film bonding technology. The basic operation of the programmable correlator is confirmed for a polarity change output signal and response for the coded signal.

Bi₄Ti₃O₁₂ (BIT) and tungsten-substituted Bi₄Ti₃O₁₂ (BTW) thin films were prepared on Pt/Ti/SiO₂/Si substrates by a sol–gel method. There are differences in the ferroelectric properties and grain strucure between BIT and BTW thin films. The crystal structure and the surface grain morphology were characterized by scanning electron microscopy and X-ray diffraction. Grains of BIT were grown with c-axis preferred orientation, while these of the BTW were randomly distributed. The ferroelectric properties and polarization fatigue characteristics were confirmed by the P-E hysteresis loops. The BTW thin film was measured to have remanent polarization (2P_r) of 27 µC/cm² and a coercive field (2E_c) of 130 kV/cm. The dielectric constant and loss tangent at 1 MHz were measured as 210 and 0.05, respectively. On adding a small amount of tungsten in Bi₄Ti₃O₁₂, the remanent polarization increased and fatigue resistance improved.

We developed an apparatus to conduct relative permittivity measurements for supercritical fluids. It was designed to measure the values with sufficient accuracy by a convenient and simple treatment. The use of pressure-tight coaxial cables decreased the electrical noise and stray capacitance, and made it possible to use a small-sized ordinary capacitor with a multi-layered structure of parallel plates. As a result, permittivity of supercritical fluids was measured within an uncertainty of ±0.1% even for the thermodynamic state in the vicinity of the critical point. Using the apparatus, the relative permittivity of C₂H₄ was measured at six temperatures near the critical temperature in the pressure range of 0.1–10 MPa. It was proved that there definitely exists a critical anomaly of molar polarization P_m with a temperature dependence.

The nonreducible mechanism of {(Ba_1-xCa_x)O}_mTiO₂ (m>1) ceramics fired in a reducing atmosphere was investigated by measuring the electrical conduction under various atmospheres at elevated temperatures. The high insulation resistance of the Ca-doped BaTiO₃ ceramics can be explained by the following three factors; (1) the decrease of electron concentration in the lattice by the substitution of Ca²⁺ ions for the Ti⁴⁺ site, (2) the high enthalpy change of the reduction reaction by the substitution of Ca²⁺ ions for the Ba²⁺ site, and (3) the low freezing temperature of the equilibrium reaction due to high concentration of the extrinsic oxygen vacancies developed by Ca²⁺ ions on the Ti⁴⁺ site.

As liquid crystal (LC) materials for TFT-TN display, two-ring and three-ring homologues with 2-fluoroisothiocyanatophenyl and 2,6-difluoroisothiocyanatophenyl with high dielectric anisotropy and birefringence are prepared. In spite of the existence of a high polar –NCS group, the voltage holding ratio (VHR) of NLC mixtures contained in them is sufficiently high for application of active matrix addressing. In this paper, we will explain the voltage holding property of three types of liquid crystal materials included the terminal –NCS group considering their molecular parameters such as the Hückel charge, polarizability and dipole moment and the temperature and frequency dependence of voltage holding ratios are examined.

Photoaligned monomolecular layers containing two materials were formed to control pre-tilt angles (θ_p) of liquid crystal molecules for twisted nematic (TN) type liquid crystal displays (LCDs) by a chemical adsorption (CA) technique and a photoalignment technique. One was a new chlorosilane type surfactant, 4^'-(6-trichlorosilyloxyhexyloxy) chalcone (CO), having photopolymerizablity, and the other was a surfactant having a straight carbon chain (SC). Although we tried screening six different surfectants as an additive to CO, a surfactant having a long straight hydrocarbon chain (octadecyl-trichlorosilane: C18) was the most suitable for the TN type LCDs. By changing the molecular ratio of CO and C18, pre-tilt angles of liquid crystal molecules in a test liquid crystal (LC) cell could be controlled from 0 to 8° with perfect mono-domain alignment. When surfactants having short hydrocarbon chains and those having fluorocarbon chains were used, the quality of the TN type LC cells obtained was not good.

A noncontact laser ultrasound technique is applied for the measurement of multi-mode dispersion relations of Lamb waves propagating in an LiNbO₃ plate with different propagating directions. Also, a theoretical treatment based on a partial wave analysis is provided for the calculations of dispersion relations. For all the propagation angles, the measured dispersion curves show good agreement with the theoretical calculations. The Rayleigh wave speeds are extracted from the measured and calculated dispersion curves, showing favorable agreement with classical theory by Campbell.

To support the requirement for faster switching times, newly developed liquid crystal (LC) mixtures were designed using fluoro-isothiocyanated phenyl liquid crystals. In this study, in order to improve switching time, important reductions in the viscoelastic coefficient, γ₁/K_eff, are demonstrated and a numerical evaluation of switching properties vs various switching parameters in the fluoro-isothiocyanated phenyl liquid crystals was performed.

A computer simulation study of self-diffusions along the cores of four different Shockley partial dislocations has been carried out for fcc C₆₀ crystals. The spherical intermolecular potential derived by Girifalco has been used. Computations show that in the case of a monovacancy mechanism, migration energy along the dislocation core is lowered to 2.6 eV from 6 eV in the perfect crystal, at maximum. For a divacancy mechanism, it is lowered to 1.8 eV from 2.6 eV in the perfect crystal, at maximum.

Hexafluoroacetylacetonato copper(I) trimethylvinylsilane [Cu(hfac)tmvs] is currently the most documented precursor for copper chemical vapor deposition (CVD) for semiconductor applications. It is well known that some amount of moisture in the process chamber enhances the deposition rate. In the present study, we found that a water-premixed precursor could be made stable provided that the water was free from any trace of dissolved oxygen. Further improvement in stabilization was obtained in both cases by adding free tmvs. The practicality of this water-premixed precursor was also demonstrated for Cu deposition. No difference was observed for the deposited films in terms of their resistivity, crystallography, purity, or uniformity between the water-premix condition and separate addition of moisture. Furthermore, the optimum moisture concentration for copper deposition was lower than the solubility limit of water in the precursor, which makes this solution of practical interest. We conclude that the water-premixed Cu(hfac)tmvs is a suitable and sophisticated solution for application in the copper CVD process that reduces the hardware burden on the tool and limits the number of process variables.

It is well known that many cracks almost constantly occur in diamond films grown on conventional insulating wafers (such as silica glass or sapphire chips). In the present study, we used SiO₂/Si substrates instead of the conventional insulating wafers for diamond deposition, and the growth of diamond was performed in a microwave plasma–enhanced–chemical–vapor–deposition (MPECVD) system. It was confirmed that both crackless microcrystalline and crackless nanocrystalline diamond films can be successfully deposited on the insulating SiO₂/Si substrates under various growth conditions, suggesting that SiO₂/Si is a promising candidate for an insulating substrate in diamond growth. The reasons why the cracks can be effectively prevented on SiO₂/Si substrates rather than on silica glass or sapphire wafers are well explained with respect to the thermal expansion theory.

In order to determine the selection of the extreme ultraviolet (EUV) mask substrate, an assessment model based on the temperature profile along the substrate thickness is proposed. Regarding the glass ceramic materials, thermal deflection and displacement due to thermal expansion are compared as functions of the heat transfer coefficient between the mask and the stage. Displacement is small although the thermal deflection is large in the region where the heat transfer coefficient is sufficiently high. Marginal EUV power density used for 35 nm node is determined by the substrate material and exposure conditions. Throughput estimated by EUV power density and exposure conditions depends on the substrate material. It was shown that a throughput of 60 wafer per hour (wph) is possible under conditions equivalent to low pressure in a helium environment.

To minimize degradation reactions occurring at the same time as surface modification reactions, the surface modification of poly(aryl ether ether ketone) (PEEK) film surfaces by pulsed oxygen plasma was investigated. Oxygen radicals and ion and electron concentrations in the oxygen plasma were calculated as a function of the elapsed time after the discharge was turned off. The pulsed plasmas showed a low contact angle compared to those treated with continuous plasma, though the weight loss of the pulsed plasma irradiated sample decreased compared to those irradiated by continuous plasma. X-ray photoelectron spectra (XPS) measurements indicated that oxygen groups were formed on the PEEK surface.

Electrical properties of a Pt/C₆₀/In/Al Schottky-barrier cell have been studied by an admittance measurement carried out in the frequency range between f=0.2 Hz and 100 kHz, and also by a current density–voltage (J–V) measurement. The J–V measurement shows that the rectification is caused due to the asymmetry of electron injection efficiencies from the electrodes. The conductance G_p and capacitance C_p are significantly affected by the localized charges produced by the injection from the electrodes or by illumination. From the frequency dependence of G_p and C_p, it is estimated that the dielectric relaxation time of the localized charges is ∼0.3 s and the value of N_Lξ² at zero bias in the dark is of the order of 10⁶ m^-1, where N_L is the density of the localized charges in the C₆₀ layer and ξ is the distance which determines the electric dipole moment µ of a localized charge by the relationship µ=eξ. N_Lξ² increases significantly by the application of a forward bias or by illumination.

Thermal diffusion of copper in a Cu/TaN/Si-sub sample was investigated after annealing at 630°C for 60 min. The interface morphology, copper silicide grains and SiO₂ thin layer were observed using high resolution transmission electron microscope (HRTEM). Depth profiles were obtained with an energy dispersion X-ray spectrometer (EDS) assembled in the TEM system. Based on the grain boundary theory of Fisher and the approximation solution of Le Claire, thermal diffusivity of copper into the tantalum nitride layer was estimated.

In the present article, we compare the morphology and microstructure of hard (<40 GPa) and superhard (>40 GPa) Zr–Cu–N nanocomposite films. It is shown that the morphology strongly depends on the Cu content in the film. The film with a low (1–2 at.%) Cu content exhibits a columnar structure. In contrast, films with a higher (>5-6 at.%) Cu content have a globular structure. The hardness of films depends on both the Cu content in the film and the structure of individual phases of the nanocomposite. The nanocomposite film of type nc-/nc- exhibits higher hardness than that of type nc-/a-; here "nc-" and "a-" denote the nanocrystalline and amorphous phases, respectively. The film of type nc-ZrN/nc-Cu with a low (1–2 at.%) Cu content exhibits the highest hardness of 50 GPa.

The surface microstructure of sapphire (α-Al₂O₃) substrates could be constructed at room temperature via selective sapphire homoepitaxial growth induced by electron beam irradiation in laser molecular beam epitaxy. The films grew homoepitaxially on sapphire (1012) substrates at room temperature only in the region electron-irradiated during film deposition, while amorphous aluminum oxide films grew in the non-irradiated area. The surface micropatterns on sapphire substrates were easily obtained by the selective H₃PO₄ wet etching of the modified sapphire surface coated with crystalline and amorphous film. The microwall and microgroove could be fabricated on the sapphire substrates at room temperature.

A ferrite sharpener is a nonlinear coaxial line using ferrite beads which produces high-voltage, high-dV/dt pulses. We examined the characteristics of ferrite sharpeners experimentally when the following parameters were changed independently: (1) magnetic field bias, (2) amplitude of input voltage pulse, (3) rise time of input voltage pulse and (4) sharpener length. Then we made a simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. The predictions of the simulation are found to be in good agreement with the experimental results, thus it is confirmed that the simulation is a powerful tool for designing the sharpener.

In this paper, computer simulations of the physical phenomena occurring in the arc region before and after current zero were carried out to evaluate the dielectric recovery characteristics of two types of dual-flow nozzles. A commercial computational fluid dynamics (CFD) program "PHOENICS" was used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by comparison with the test results presented by the research group of BBC. In order to investigate the state of the arc region after current zero, the simulations were carried out in four steps, cold gas flow analysis, steady state arc simulation, transient arc simulation before current zero, and transient hot-gas flow simulation after current zero. The semi-experimental arc radiation model was adapted to consider the radiation energy transport and Prandtl's mixing length model was employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The streamer criterion was introduced to evaluate the dielectric recovery characteristics after current zero. Compared with the results obtained by assuming the current zero state in the former studies, it has been found that the results obtained by considering the state before current zero were more accurate.

A new protective layer, incorporating carbon nanotubes (CNTs) under the conventional MgO protecting layer, was proposed and a prototype of an AC-plasma display panel (PDP) was fabricated using this protective layer. The discharge characteristics were obtained for these prototypes and explained in terms of the high secondary electron emission yield of the MgO/CNT layer. Thus, this MgO/CNT layer can be considered as a potential protective layer for use in AC-PDPs.

We have applied a compact electron-bean-excited plasma (EBEP) source to the cleaning process for a glass disk. Since the EBEP enables us to control the ion sheath bias on the floating substrate by changing the electron-beam energy, the substrate ion bombardment energy to perform a reactive ion etching (RIE) can be determined without applying additional bias power supply such as RF. The source system has been modified in several ways so that it can be reliably used in the O₂ plasma for a long time. In order to evaluate the cleaning capability of the source system, the etch performance of carbon film was investigated. It was found that the etching rate increased with electron-beam current and electron acceleration voltage. The etch rate of 4 nm/s was obtained at V_a of 100 V and I_a of 2.5 A.

A rotating helical magnetic field (RHF) makes an effective recycling wall area increase so that the wall pumping may be enhanced more than that in the absence of RHF by rotating a poloidally periodic edge magnetic field structure. On the other hand, a mitigation of the toroidally asymmetric recycling property due to the RHF has been observed. The reason for such a mitigation of toroidal inhomogeneity comes from the fact that the application of the RHF moderates a toroidal nonuniformity of the plasma flux to the wall while the original plasma-wall interaction is nonuniform toroidally due to a shift of the toroidal plasma loop. Such mitigation is discussed, employing a one-dimensional numerical modeling.

A new type of sputter ion plating system with facing target sputter and immersed inductive coupled plasma (ICP) source was developed for hard coating of metals and various compound materials. The precise control of plasma conditions, such as ion bombardment energy and electron properties, was very important for high-quality film formation. The electron density (n_e) of 10¹⁰–10¹² cm^-3 was obtained in the discharge region, and the electron temperature (T_e) was in the range of 2.5–5.7 eV. The adhesive force of the TiN film prepared by this system on the stainless steel substrate was in the range of 20–50 N in the scratch test. The mechanical characteristics of TiN film such as adhesion and hardness almost completely depend on the ion energy incident onto the substrate, whereas the reactivity has a deep correlation with the density of RF plasma.

In this study, N₂O and NO were added as additive gases to C₄F₈O/O₂ for plasma enhanced chemical vapor deposition (PECVD) silicon nitride chamber cleaning and their effects on the emission properties of perfluorocarbon compounds (PFCs) were investigated. The cleaning rate, destruction and removal efficiencies (DREs), and million metric tons of carbon equivalent (MMTCE) were studied as a function of flow rates of PFCs and additive gases. The use of C₄F₈O/O₂ alone showed the highest cleaning rate and the lowest emission properties at the cleaning condition of 20%C₄F₈O/80%O₂, working pressure of 500 mTorr, and 13.56 MHz rf power of 350 W. By the addition of about 20% NO or 20% N₂O to the optimized C₄F₈O/O₂, the additional reduction of MMTCE higher than 50% could be obtained. The addition of NO resulted in lower MMTCE compared to that in the case of the addition of N₂O mostly due to the higher silicon nitride cleaning rate in the latter case.

A collective Thomson scattering (CTS) system based on CO₂ laser is being developed in JT-60U to demonstrate the feasibility of ion temperature and alpha particle measurement in international thermonuclear experimental reactor (ITER). A new and effective method of measuring the spatial profile of absolute detection efficiency of an infrared heterodyne receiver has been developed for the CTS system. The viewing area and divergence of the field of view were first investigated with this method. Consequently, the spot size of the field of view could be narrowed to 0.74 mrad by adjusting the focal length of the local oscillator. The effective sample volume length determined by the injection beam waist and divergence of the field of view was also investigated.

In this paper we propose a method to decelerate polar molecules in a ring electrode. Trapped molecules rotate around the ring-axis, whose rotation radius can be changed arbitrarily. On increasing the rotation radius, the tangential velocity decreases keeping the angular momentum around the ring axis constant.

We have measured electron and hole mobilities in vacuum-deposited film of 2,5-bis(6^'-(2^',2^''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy) using a time-of-flight technique. The PyPySPyPy has a bipolar transport property and both its electron and hole mobilities are over 10^-4 cm²/Vs. Multilayered organic electroluminescent (EL) devices consisting of N, N^'-diphenyl-N, N^'-(3-methylphenyl)-[1,1^'-biphenyl]-4,4^'-diamine (TPD) as a hole transport layer, tris (8-quinolinolato) aluminum (III) (Alq₃) as an emitting layer, and PyPySPyPy as an electron transport layer exhibit a very low operational voltage of 3.6 V for obtaining 1,000 cd/m². The Schottky barrier height at the PyPySPyPy/Al interface was 0.59 eV, and the value was obviously smaller than that in the case of the Alq₃/Al interface.

In situ polymerization of polypyrrole (PPy) in various alcohols and water/methanol mixture solvents has been studied. The deposition rate in alcohols has been found to be slower than that in aqueous solution with the same composition, approximately 1–2 nm/min, by two orders of magnitude. On the other hand, the electrical conductivity of PPy films deposited in alcohols ranged from approximately 10^-6 S/cm to approximately 1 S/cm, depending on the solvent, while that in aqueous solution was approximately 100 S/cm. These results suggest that the replacement of the solvent water with alcohols induces drastic deactivation of FeCl₃ as an oxidizer. The surface morphologies of the PPy films deposited in alcohol solutions mimic those of PPy films deposited in aqueous solutions. For in situ polymerization of PPy in water/methanol mixture solvents, it has been found that the electrical conductivity as well as the deposition rate is continuously and monotonically tunable by changing the methanol content. This indicates that the utilization of a mixture solvent is a promising way to control the electrical conductivity as well as the deposition rate.

Low-energy electron transmission (LEET) experiments were performed for the indium/perylene-3,4,9,10-tetracarboxylic dianhydride (In/PTCDA) system prepared by a sequential deposition of PTCDA and In on a MoS₂ single crystal surface. The dependence of LEET spectra and the work function change (Δφ=φ_film-φ_substrate) on the deposition amount of In on the PTCDA monolayer showed that the organic-metal compound of In₄PTCDA was formed at the In/PTCDA interface. The result is in good agreement with that previously obtained using metastable atom electron spectroscopy. Furthermore, from the temperature dependence of LEET spectra and Δφ for the In/PTCDA system, we propose that in the as-grown In₄PTCDA at room temperature In atoms are located out of the PTCDA plane, and after heat treatment, it becomes a planer structure.

In this paper, a piezoelectric impact hammer is designed and fabricated for generating stable repeated impact elastic waves and further for in-situ wave velocity measurements of concrete specimens. The piezoelectric impact hammer consists of a stacked multilayer PZT, a flying head system with an on-line load cell embedded and a holding fixture. To measure the longitudinal or Rayleigh waves of a concrete specimen, two horizontally polarized conical transducers are utilized to receive the elastic waves generated by the piezoelectric impact hammer. Due to the stable impact generation of the piezoelectric impact hammer, the experimental results showed that the accuracy of the wave velocity measurement was enhanced significantly through the signal averaging. Since the impact time origin of the newly designed impact hammer can be determined accurately, it was utilized to measure the depth of a normal surface-breaking crack in a concrete specimen, and the result is very accurate. We note that the results of this study offer a precise and convenient way of measuring in-situ elastic properties and/or crack depth of concrete specimens.

The effect of ultrasonic vibration in the Reynolds number (Re) range of 1500 to 6000 on fluid flow in a square channel was investigated experimentally. An ultrasonic transducer was fixed at the center of the bottom of a square test channel, and a standing wave field was formed in this channel. The velocity of the fluid was measured by a laser-Doppler velocimeter (LDV). By applying ultrasonic vibration to the laminar flow, agitation or disturbance of cavitation bubbles was produced in the flow and the transition to turbulent flow from laminar flow was promoted downstream. The ultrasonic vibration velocity near the wall is closely approximated by the expression of the log-law even if there exists a laminar flow region. In high Re regions, turbulence can be restrained by the ultrasonic vibration near the wall. Acoustic cavitation near the wall causes the reduction of turbulence intensity under turbulent regions. Since it is possible to control the fluid flow externally due to the easy transmission of ultrasonic vibration in liquids, this technique can be applied to fluid flow in various channels as a noncontact turbulence promoter.

The figure of merit ZT of thermoelectric materials has been evaluated by the Harman method in the temperature region below room temperature. In this method only resistance measurements by both dc and ac methods are required to obtain the ZT values. ZT is given by ZT=(R_dc/R_ac-1)/x, where R_dc, R_ac and x are the resistance value by the ac and dc methods and the rate of the heat to the heat bath, respectively. The heat effect is experimentally confirmed to be negligibly small and we can use x=1 which corresponds to a sufficient adiabatic condition. Because an ambiguity due to experimental errors such as the length between the measurement terminals in the resistivity and the thermal conductivity measurements is removed, ZT can be determined very simply and precisely by the Harman method.

Extraction of coupling of modes (COM) parameters from the manufacturing process of a surface acoustic wave device (SAW) is important in practice. In this study, we employed an inverse algorithm to recover the COM parameters from the measured admittance of a one-port SAW resonator. For completeness, the COM equations, the P-matrix representation and the related COM parameters have been summarized. The admittance of a one-port resonator was derived based on the P-matrix representation. One-port and two-port SAW resonator filters were fabricated and the related responses were measured. The simplex method was then used to determine the COM parameters inversely. The recovered COM parameters of the one-port SAW resonator have been demonstrated to be applicable to simulate not only the frequency response of the one-port SAW resonator but also that of the two-port one.

An in-situ size monitoring system for small batteries was designed, and the thickness changes of Li-ion polymer batteries were measured during charging and high temperature storage. An eddy current displacement sensor works without contacting the sample and provides a compact and heat-resistant measuring unit. Three types of thickness changes were observed, which originated from an active material expansion by Li intercalation, a thermal expansion, and the gas generation due to the material decomposition.