bluuebunny/crossref_metadata_2025_split huggingface dataset:
LSI fabrication process evaluation system utilizing simulators
Authors: Tazawa Satoshi , Kubota Katsutoshi , Wada Kou 
Published: July 2007

AbstractWe propose a process evaluation method using channel‐doped MOS devices and process/device simulators for quantitative evaluation of contamination and surface condition. The amount of contamination is determined by comparison of the measured and simulated C‐V characteristics of an MOS capacitor. Then the MOS FET is evaluated by comparison with a theoretical ideal I‐V characteristic calculated from the MOS capacitor measurement data and the doping profile. The surface condition is evaluated by determining the carrier mobility from MOS FET characteristics. With these evaluation methods, we develop a new process evaluation algorithm to determine the cause of processing irregularities, whether due to contamination, damage, faulty pattern delineation, or other factors. By combining a process data base and process device simulator, we develop a process evaluation system to facilitate application of the new evaluation method. It is applied to the evaluation of MOS LSI processing.
Modeling of etching process via kalman filter and channel length control
Authors: Matsuba Ikuo , Matsumoto Kuniaki , Kobayashi Kazunari 
Published: July 2007

AbstractIn semiconductor fabrication it is difficult to form channels with precisely controlled lengths, even when using plasma etching which itself is highly precise. This is because of fluctuations in the processes preceding the etching, as, for example, in the developed resist dimensions. This paper proposes a method for controlling channel lengths which relies on an optimized over‐etching, the extra etching time after the normal etch completion depending on the variation in resist dimension, etc. In the method a phenomenological model is set up for the rate of change of channel length as a function of the resist dimension and etching cross section, and the polysilicon layer thickness and its phosphorus doping density as determined by sheet resistance. The model coefficients are estimated by a Kalman filter on wafer and lot measurement data. The results of production line experiments with the present method show a reduction in channel length variation by one‐half compared with the previous uncontrolled method.
Light polarization control due to electrooptic effect
Authors: Kido Yasuaki , Furuya Kazuhito , Suematsu Yasuharu 
Published: July 2007

AbstractAn analysis and experimental results are described for the automatic polarization control of the polarization plane of the output light from a single‐mode fiber with a standard axisymmetric core. This automatic polarization control device consists of two phase shifters made of z‐cut LiNbO3 exhibiting the electrooptic effect. The phase shifters are oriented with their transverse planes inclined to each other. The state of the polarization is detected by two Rochon prisms and is fed back to the phase shifters. The analysis has been done for the change of the polarization of the incident light in the polarization control device. The range of the voltage applied to the phase shifter for the control and the condition of the angle between the phase shifters are clarified. Next, experiments have been performed and the single polarization control in the desired direction has been attained. A proposal is made to simplify the control mechanism.
Computer simulation of bulk‐charge transport in small‐geometry depletion‐mes charge‐coupled device
Authors: Yonei Kenji , Omoto Osamu 
Published: July 2007

AbstractThis paper deals with a comparative investigation of small‐geometry Schottky‐barrier CCD with a depletion‐MES structure (depletion‐MESCCD). It also presents the performance evaluation of Si and GaAs D‐MESCCDs with three‐phase, low‐voltage clock pulse drive. Consequently, Poisson and continuity equations are put in difference form and a program for computer simulation of the behavior of electrons and holes in the device is developed. Simulation yields the relationship between the transfer electrode spacing and the potential and permits analysis of the carrier density, potential, leakage rate and transfer inefficiency during the charge transfer process. The results show that the potential profile of complete charge transfer with 1.2 Vp‐p of three‐phase clock pulse voltage, electrode length 0.5 μm and interelectrode distance 0.5 μm can be obtained. For CCD charge transfer with 0.6–2.0 Vp‐p three‐phase clock pulse, the leakage between bits is found to be the largest among the charge transfer leakages from all parts of the CCD. The simulation for a 1.5 Vp‐p three‐phase ramp waveform clock pulse shows that, if the charge transfer speed difference between Si‐and GaAs‐D‐MESCCD due to mobility difference is excluded, they give about the same performance.
Laser annealing of polysilicon films with an applied electric field
Authors: Okamoto Kotaro , Suzunaga Hiroshi , Kitagawa Yasuhiro 
Published: July 2007

AbstractPolysilicon films deposited on an SiO2 substrate by pyrolysis of SiH4 were annealed with a Q‐switched ruby laser while an electric field was applied simultaneously. Investigating the effet of the laser‐excited photocurrents on the anneling showed that besides a general Joule heat promotion of the annealing, there was an elongation of the crystal grains in the direction of the electric field. The effect of the electric field in causing this improvement in crystallinity can be modelled by supposing that at above about 40 MW/cm2 where annealing starts to appear, the process is a solid‐phase coalescence caused by localized heating at the high resistance grain boundaries. Then at 70 MW/cm2, the process changes into a melt recrystallization process where random nucleation is suppressed by the Joule heating. Current‐assisted laser annealing of polysilicon deposited on a grating showed that the grating steps acted as nucleation sites and that there was crystal grain elongation perpendicular to the grating direction.
High‐speed photodetectors using GaAs MESFET
Authors: Umeda Tokuo , Cho Yoshio 
Published: July 2007

AbstractThis paper deals with experimental investigations of light response performance and operation mechanisms of the GaAs MESFET when used as a high‐speed photodetector. The GaAs MESFET under test is a device used for a microwave amplifier with 1‐μm gate length and 75 ˜ 300‐μm gate width. The illuminating light is either CW (He ‐ Ne) or pulsed (dye laser with 10‐psec pulse width and 7‐nsec pulse interval). The light is focused by the object lens and illuminates the area between the source and drain within 5 μm. When the FET is in the pinchoff state the pulse response is shown to be much improved. The output current depends on the input light power and tends to saturation. Light response speed of 100 psec can be obtained from a sample with 75‐μm gate width. Observation shows that the response speed is independent of gate width. From these experiments as well as the I‐V characteristics under illumination and the appearance of the gate voltage of the I‐V characteristic without illumination, it is shown that the depletion layer is changed. Based on these observations the operation model is proposed. Guidelines for optimizing the high‐speed FET photodetector (i.e., improvement of the surface configuration for illumination, selection of the active layer and carrier density and the requirements of the surface window layer) are presented.
Analysis of oscillation characteristics for the raman‐type free‐electron laser utilizing a two‐dimensional periodic magnetic field for the pumping source
Authors: Nakano Hayato , Shiozawa Toshiyuki 
Published: July 2007

AbstractA two‐dimensional model of the Raman‐type free‐electron laser is considered. It is composed of a relativistic electron beam drifting in a parallel plate waveguide, immersed in a magnetostatic pump field with periodic variation in the direction of flow of the electron beam. For the model of the Raman‐type free‐electron laser specified here, a theoretical study on the oscillation characteristics is presented and the following results are obtained. First, the spatial growth rate of the scattered wave can be maximized by properly adjusting the ratio of the beamwidth to the separation between conducting plates of the waveguide. The magnetostatic pump field affects the growth rate through its magnitude on the beam surface and its wave number. Second, the growth rate of the scattered wave is enhanced and its frequency is lowered as the wave number of the periodic magnetic field decreases, while the former is reduced and the latter becomes higher as it increases. Third, the generation of higher‐order modes can be suppressed by reducing the wave number of the periodic magnetic field.
M2O‐Al2O3‐SiO2 glass gate PNA and pK ISFETs
Authors: Shoji Shunichi , Esashi Masayoshi , Matsuo Tadayuki 
Published: July 2007

AbstractTo improve the capability of the ISFETs for measuring pNa and pK in living bodies, the ion selectivity of its sensor M2O‐Al2O3‐SiO2 (MAS, where M is an alkali metal) glass membrane was studied. The MAS membrane has been used as an ion‐sensitive membrane of pNa and pK glass electrode and it has been known that its selectivity depends on the composition of the MAS membrane. To obtain the maximum ion selectivity of the pNa and pK ISFET, the relationship between the ion selectivity and the composition of the MAS membrane was investigated by measuring the ion selectivity over various compositions. It was confirmed that the selectivity of the MAS gate ISFET between Na+ ions and K+ ions depends on both the kind of alkaline cation and the ratio of the alkali metal to aluminum in the MAS membrane. As a result, the best composition of ion‐sensitive membranes for pNa and pK ISFET was determined. A pNa ISFET was obtained which uses the LAS membrane containing Li as the alkali metal and has a selectivity of about 200 times for Na+ ions against K+ ions with a low output‐voltage drift and a long life. A pK ISFET also was obtained which uses a KAS membrane containing K and has a selectivity of about 40 times for K+ ions against Na+ ions.
Self‐aligned bipolar transistors fabricated by selective etching of polysilicon technology
Authors: Uehara Keijiro , Higuchi Hisayuki , Iijima Shinpei 
Published: July 2007

AbstractTo fabricate submicrometer transistors practical for LSI by conventional photolithography with a minimum pattern width of 1.5 μm, a self‐aligned process using a selective etching of polysilicon technology (SEPT) has been developed. Compared with the formation of fine patterns by side etches of overhangs, this process, using an oxide thickness and a diffusion distance as a pattern width, has a high accuracy and reduces the variation of the base voltage (VBE) which becomes an important characteristic when the emitter size is reduced by a self‐alignment technique. In this method of self‐aligning the base contact and the emitter, a submicron transistor with emitter width of 0.8 μm, base‐emitter spacing of 0.4 μm, and the base contact width of 0.3 μm can be fabricated with a mask pattern of 1.5 μm width. By the reduction of the active region, the junction capacitance and the base resistance which affect the high‐speed performance have been reduced drastically. A 25‐stage, 3‐input ECL ring oscillator designed with practical rules of 1.5 μm minimum pattern width and 4.5 μm interconnection pitch has shown a delay of 95 ps (ICS = 0.78 mA). Since this method has a high‐dimensional accuracy and reduces the VBE variation which becomes an important characteristic for LSI, it can be used in further scaling.
A switched‐capacitor digital capacitance meter
Authors: Kondo Kazuyuki , Watanabe Kenzo 
Published: July 2007

AbstractA capacitance meter using switched‐capacitor circuits is developed. The capacitance under measurement is first sampled in its proportional voltage, which is then converted into the binary number by means of the cyclic analog‐to‐digital conversion. A prototype meter built using discrete components has achieved the resolution of 9 bits, measurement time of about 0.4 ms, and error less than 0.7 percent. The effect of the capacitance mismatch and clock feedthrough upon the measurement accuracy is analyzed for both the discrete and MOS IC realization. The analysis shows that 10‐bit accuracy is obtainable if the capacitance mismatch less than 0.06 percent is achieved by MOS IC realization.
Generation of electron beams by low–temperature field emission
Authors: Matsuda Jin‐Ichi , Kubo Mitsunori , Iriguchi Chiharu , Kato Kazuo , Yamashita Tsutimu , Masuda Takao 
Published: July 2007

AbstractA method is proposed of generating a fine electron beam which has an excellent monochromaticity and high brightness by using an extremely low temperature and high electric field. This paper describes the actual apparatus based on the proposal. If the cathode of the apparatus is kept at an extremely low temperature (about 4K), theoretically, the possibility exists of making the energy spread as small as of the order of 0.01 eV, while the energy spread of a conventional electron beam at room temperature with a high electric field is of the order of 0.1 eV. The prototype apparatus assembled consists of a 3‐electrode type electron emission system, the main part containing a retarding potential energy analyzer and a vacuum chamber (about 10−9 Torr) made of stainless steel. Polycrystal tungsten wire is used for the cathode. The reduction of the energy spread was not achieved for the theoretical value, because of the deposits on the tip surface due to the residual gas (notably oxygen) at the extremely low temperature (cooled by liquid helium). At a low temperature (cooled by liquid nitrogen), however, the energy spread was improved by 25% compared with that at room temperature. This shows a possible improvement of the energy spread by cooling the cathod as expected.
Reproducing process of perpendicular magnetic recording
Authors: Tanabe Shinji , Iwasaki Shun‐Ichi 
Published: July 2007

AbstractThe reproducing process of perpendicular magnetic recording is here analyzed by a finite element numerical simulation. A mechanism is found for significant improvement of reproduction sensitivity by means of a soft magnetic layer backing a CoCr medium. The analysis is conducted for a vertical head consisting of main and auxiliary magnetic poles. The magnetic field saturation and reduction are taken into account in iterative calculation based on the Newton‐Raphson method. In calculation of the magnetic field reduction a measured M‐H loop for CoCr including the minor loop is used. It is found that the soft magnetic backing layer increases by an order of magnitude the amount of magnetic flux flowing deep into the main pole. This finding confirms experimental observation that the reproduction output increases by an order of magnitude with the backing layer. The paper also describes the spacing loss in reproduction of perpendicular recording. A more useful definition of reproduction efficiency of the head is found from the above results. The computation procedure is useful in analysis of a nonlinear reproduction process.
Analysis of a ringing choke converter
Authors: Ninomiya Tamotsu , Higashi Tooru , Harada Koosuke 
Published: July 2007

AbstractThe ringing choke converter is widely used as an electronic power supply with a small capacity. A number of works have been published on the feedback systems for adjustment of output voltage. No sufficient analysis, however, has been undertaken on the static and dynamic characteristics. In this paper, a nonlinear differential equation describing the basic operation is first derived. Next, from a small signal model obtained from this differential equation, a loop transfer function of the converter is derived. Further, the transfer function for an input variation and a load variation under regulation have been derived. As a result, the characteristic equation becomes linear and it is shown that the converter is extremely stable. The dynamic characteristic parameters of the ringing choke converter are found different from those of the conventional reactor current discontinuity mode converter. Both the gain bandwidth product of the loop transfer function and that of the transfer function of the output voltage fluctuations for the input voltage fluctuations under regulation are smaller in the ringing choke converter than in the reactor current discontinuous mode converter. It is found that the ringing choke converter is less susceptible to the input voltage fluctuations and operates with a greater stability than the reactor current discontinuous mode converter.
Evaluation of contact resistance characteristics for tin plated connector contacts in accelerated degradation test
Authors: Yasuda Kei‐Ichi , Aoki Takeshi , Imori Yasutaka 
Published: July 2007

AbstractTo find applicability of tin/tin contacts to connectors used in communication systems requiring high reliability electrical connection, damp heat cycle tests have been carried out and the accelerated degradation characteristics of the tin/tin contact have been compared with those of the gold/gold and gold/tin contacts. The results are as follows. (1) The contact resistance of the tin/tin contact is close to that of the gold/gold contact and it was found to be a reliable contact in high reliability connectors for the first 20 insertions. (2) In the tin/tin contact, the worn‐off area is smaller and the apparent contact area is larger than in the gold/tin contact. These factors contribute to the stability of the contact resistance and are basis for contact resistance in the tin/tin contact is more stable than in the gold/tin contact. From these results it is found that the tin/tin contact can be used in high reliability connectors within the range of a few insertions.
Photoconductive characteristics and stabilization of hydrogenated amorphous silicon films
Authors: Takahashi Minoru , Nozawa Toshinori 
Published: July 2007

AbstractThis paper describes the changes in the photoconductive characteristics under elevated environmental conditions and presents a stabilizing method of hydrogenated amorphous silicon (a‐Si:H) thin films. a‐Si:H is decomposed from silane in a PCVD (Plasma Chemical Vapor Deposition) apparatus. The results of high‐temperature and high‐humidity storage tests reveal that the photocurrent increased by about two orders of magnitude over the initial value, followed subsequently by a gradual decrease. The data analyzed through ESR, SIMS and IR absorption spectroscopy confirmed that these photocurrent changes are closely related to the reduction of dangling bonds, exodiffusion of hydrogen and gas adsorption, such as H2O molecules, onto the film surface. The characteristics were stabilized through coating the film surface with a silicon nitride film deposited at room temperature by ECR (Electron Cyclotron Resonance) plasma CVD.
Effective cutoff frequency of LP11 mode in uniformly curved step–index optical fibers
Authors: Tanaka Toshiaki , Morita Nagayoshi , Kumagai Nobuaki 
Published: July 2007

AbstractThis paper evaluates the field distribution and the propagation constant of the LP11 mode propagated in circularly bent step‐index optical fibers by considering these quantities as perturbations from those in the straight fiber. By using these results, the field distributions and the curves of solutions of the eigenvalue equations for the bent fiber are studied in detail based on numerical and physical considerations. On the basis of this study, a reasonable method is proposed for defining the effective cutoff frequency of the LP11 mode in a circularly bent section of a step‐index fiber. Also, an easier method of obtaining the approximate value of this effective cutoff frequency is presented. It is confirmed that the effective cutoff frequencies calculated according to the definition proposed herein become very close to those effective cutoff frequencies used until now, i.e., those values based on the difference between the measured losses of the LP11 mode and the LP01 mode.
Characteristics of pattern peak–shift in digital magnetic recording
Authors: Nishikawa Masaaki , Kirihara Akio , Doi Yukihiro 
Published: July 2007

AbstractPattern peak‐shifts due to the interference of adjacent magnetization transitions in digital recording are one of the main causes of limiting its recording density. This paper aims to supply design data on pattern peak‐shifts, giving experimental data of peak‐shift in various transition patterns, and comparing them with the calculated results obtained from the superposition of isolated read signals. A magnetic tape system was used in which a nonlinear interference effect occurs easily during the write process.The relationship between the peak‐shift in a magnetic transition pattern Δx and the minimum magnetic transition interval b is given in a normalized graph coordinated by Δx/b and b/(W50/2), where W50 is the half‐width of an isolated read signal. For example, the design value of b/(W50/2) for required value of Δx/b ≤ 25% is about 1.3, 1.0 and 1.2 or greater for the NRZ‐I, FM and MFM code systems, respectively. The nonlinear interference in a recording process occurs so that each magnetization transition is pushed toward the direction of medium motion. In a region where this effect occurs strongly, the calculated results do not agree with the actual ones.
Elimination of spurious solutions in vectorial finite–element analysis of dielectric waveguides–A method using transverse magnetic–field component
Authors: Hayata Kazuya , Koshiba Masanori , Eguchi Masashi , Suzuki Michio 
Published: July 2007

AbstractThis paper formulates a new finite‐element representation for the vector analysis of dielectric waveguides, using the transverse magnetic‐field component. This approach starts from the earlier finite‐element formalism using all magnetic‐field components. Considering the condition V Δ H × 0 by the same technique as in the master‐slave method, and eliminating the longitudinal magnetic‐field component, the equation only for the transverse magnetic‐field component is derived and solved. By this scheme, the spurious solutions (nonphysical solutions), which have been produced inevitably in the earlier vector finite‐element analysis, is now eliminated completely from both fast‐ and slow‐wave regions. To verify the validity and the effectiveness of the present scheme, the analysis is made for a dielectric‐loaded rectangular waveguide. The results of analysis are compared with those of exact analysis and by other methods, indicating the effectiveness of the present finite‐element formulation. The present method does not involve any arbitrary constant, such as the penalty coefficient in the penalty method. The size of the matrix equation to be solved is two‐thirds that of the penalty method, which improves the efficiency of numerical computation considerably.
SH wave device for HF–band frequency modulator and demodulator
Authors: Toda Kohji , Mizutani Koichi 
Published: July 2007

AbstractThis paper describes the shear horizontal (SH) wave devices for frequency modulation and demodulation in the HF band. By means of a numerical analysis, it is found that the zeroth‐order symmetric SH mode in a horizontally poled piezoelectric ceramic plate is useful for this purpose. It has a low dispersion, low velocity and high coupling coefficient. SH wave devices as small as IC chips are useful in the HF band. The frequency characteristics of the frequency modulator and demodulator are from dc to 200 kHz and their linear conversion bandwidth is 60 kHz. These devices are useful for signal processing devices and sensors in the HF band.