bluuebunny/crossref_metadata_2025_split huggingface dataset:
Issues and perspectives in multilevel interconnection technology for quarter‐micron generation
Authors: Shibata Hideki 
Published: July 2007

AbstractThe size of elements in an integrated circuit has been reduced according to the proportional reduction scenario (scaling scenario) which has been essential in achieving high integration and high performance of Si ULSI.In this paper, the issues and perspectives in reducing the dimensions of the interconnections will be reviewed. Then the influence of the RC delay caused by interconnection resistance and capacitance which are expected to be more serious in the quarter‐micron generation on the device performance will be discussed. In addition, a new scaling scenario needed to reduce the interconnection delay in accordance with the improvement of device performance will be proposed. At the same time, a way to improve interconnection reliability in high current density, planarization techniques, and self‐aligned techniques will be discussed.
An amorphous Ti‐Si‐N diffusion barrier layer for cu interconnections
Authors: Iijima Tadashi , Shimooka Yoshiaki , Suguro Kyoichi 
Published: July 2007

AbstractThis paper discusses the amorphous Ti‐Si‐N diffusion barrier layer without crystalline grain boundaries. The Ti‐Si‐N layers were sputter‐deposited in Ar‐N2 mixture gas using TiSi and TiSi2 targets. In particular, films with a composition of Ti: Si: N = 1: 1: 1.4 were evaluated. It was confirmed that the films were amorphous and thermally stable. The stress of the films was low and compressive, where it was 0.28 GPa. The junction leakage current measurement indicated that the barrier characteristic was effective at 600°C. Therefore, it was concluded that the amorphous Ti‐Si‐N layer could be used as a barrier for Cu interconnections.
Optimization of silicide process for sub‐0.1‐μm CMOS devices
Authors: Gotoh Ken‐Ichi , Fushida Atsuo , Yamazaki Tatsuya 
Published: July 2007

AbstractA silicide process is indispensable to reduction of the parasitic resistance of deep submicron CMOS devices. The parasitic resistance degrades the operating speed of ultrafine gates, limiting development of further scale‐down CMOS devices. However, the conventional silicide process causes many problems, such as agglomeration, junction leakage and thermal instability, and cannot be used for mass production of deep submicron semiconductor devices. The limitations of conventional Ti, Pi, Ni, and Co silicide processes are investigated and analyzed, and it is found that a TiN‐capped Co silicide process is suitable for fabricating 0.1‐μm CMOS devices.
Development of a thermally controlled magnetization actuator (TCMA) for a micromachined motor
Authors: Hashimoto Etsu , Uenishi Yuji , Tanaka Hidenao , Watabe Akinori 
Published: July 2007

AbstractThe magnetization microactuator has several advantages including a long‐range operation and a self‐latching actuation which are not available in an electrostatic microactuator. However, the magnetic actuator using an electromagnetic coil is not suitable for micromachining due to its structural complexity. A new magnetic actuator (thermal magnetization‐controlled actuator) is proposed which does not require an electromagnetic coil due to the control of the magnetic force by heating the thermo‐sensitive magnetic material with a permanent magnet as the source of the magnetomotive force. The operating principle and the configuration are described. Further, a static torque was measured with a millimeter‐size torsional oscillator.It was demonstrated that the static torque is reduced to less than 20 percent by thermomagnetic control so that more than 80 percent of the magnetic torque in the excited state can be used for torque generation. On the basis of this experimental result, the generated power of the thermally controlled magnetization actuator was discussed in comparison to the electromagnetically controlled actuator. It was demonstrated that the thermal magnetization control is an effective driving principle of micro‐machines.
Modeling and simulation of blanket chemical vapor deposition of WSix from WF6/Si2H6
Authors: Egashira Yasuyuki , Aita Hirofumi , Saito Takeyasu , Shimogaki Yukihiro , Komiyama Hiroshi , Sugawara Katsuro 
Published: July 2007

AbstractThe reaction mechanism of blanket chemical vapor deposition of WSix from WF6/Si2H6 mixture was modeled based on the data of a tubular reactor. In this reaction, film deposition is initiated by radical chain reaction and the silicon concentration in the film can be increased easily. The model is as follows. During radical chain reaction, reaction between WF6 and Si2H6 takes place, Si‐rich intermediary product with Si/W = 2 is formed and reaction between the product and Si2H6 causes an increase of Si concentration. The Si concentration profile in the film in the reactor could be simulated by using the reaction speed constant as a fitting parameter and the validity of this model was confirmed. The activation energy of this reaction was 23.5 kJ/mol. Using this model, the Si concentration in the film formed in the substrate‐heating‐type reactor could be predicted.
Degradation mechanism of contact resistance during window formation
Authors: Sekine Makoto , Kakuhara Yumi , Kikkawa Takamaro 
Published: July 2007

AbstractThis paper describes a contact degradation mechanism during window formation followed by selective tungsten chemical vapor deposition (W‐CVD). Contact resistances by using selective W‐CVD were increased as the overetching rate increased. Surface analysis made it clear that the Si surface at the bottom of contact was damaged and oxygen atoms from dielectrics were introduced during window etching. These damage and oxygen atoms break Si‐Si bonds and make Si‐O bonds after additional ion implantation. The Si‐O bonds degrade the valence‐band density of states of the Si surface. Such a damaged surface will not react with WF6. This inactivation is the reason for contact degradation. Controlling the Si surface state by using the chemical dry etching (CDE) technique solves this problem.
Lamé‐mode piezoelectric resonators using LiNbO3 crystals
Authors: Nakamura Kiyoshi , Kumasaka Katsunori 
Published: July 2007

AbstractPiezoelectric resonators with a simple supporting feature have been in demand for numerous applications. In this paper, it is shown that the Lamé modes having vibration nodes at the four corners exist in a rectangular 155° rotated Y‐cut LiNbO3 plate with a length‐to‐width ratio of an integer number. The theoretical analysis of equivalent circuit parameters such as capacitance ratio, indicates that this mode can efficiently be excited piezo‐electrically. In addition, it is shown that the experimental results of the impedance characteristic, displacement distribution, and capacitance ratio of the Lamé mode resonators agree with the theoretical results. It is proved that the changes in the resonant frequency and the Q value due to the four corner supports are small.
Jitter stability in paired soliton transmission system
Authors: Sakai Atsumasa , Fujii Yoichi 
Published: July 2007

AbstractThe concept of diversity transmission was applied to the optical soliton communication system. For system configuration, two transmission lines are used and an optical coupler is inserted along the way. The configuration is resistant to Gordon‐Haus jitter caused mainly by the amplification spontaneous emission (ASE) noise from the optical amplifier. Using the present method, it shows that the timing jitter can be stabilized if the perturbation of the jitter is less than the width of the soliton pulse. It is also shown that the effect of the random phase variations received along the optical fiber transmission with a large effect of perturbation (such as the nonuniform distribution of the index of refraction) can be compensated. The paired soliton transmission system is the one for which a high transmission stability can be expected even in a transmission path with a large effect of the random jitter.
Fabrication of dispersive fibers and their application to long wavelength‐pass filters
Authors: Nishimura Junji , Ueda Yutaka , Morishita Katsumi 
Published: July 2007

AbstractDispersive fibers are fabricated in which the refractive index dispersions of the core and cladding cross at a certain wavelength. The core and cladding were made of different types of optical glasses. To pass a long wavelength light (to suppress short wavelength light), the refractive index of the core was chosen to be lower than that of the cladding in the short wavelength region. In the fabricated dispersive fibers, no waveguide mode was observed in the short wavelength region, indicating that the fibers play the role of a long wavelength pass filter. To evaluate the fibers as an optical filter, the transmission loss and insertion loss were investigated and it was found that the pass wavelength region could be controlled by changing the curvature of the fibers.
two‐dimensional transient analysis of in‐plane vibration in rectangular plates of piezoelectric ceramics
Authors: Sato Masahiro 
Published: July 2007

AbstractIn‐plane vibration in rectangular plates of piezoelectric ceramics which were polarized along the direction of plate thickness was investigated by two‐dimensional transient analysis. In this analysis, it was assumed that both the top and bottom surfaces of the rectangular ceramic plates were electroded entirely and the four‐edge surfaces were not constrained. The spatial network method was employed for numerical analyses. Transient responses were evaluated numerically first for the cases where stepwise input voltages were applied to square plates.In‐plane wave motion and displacements of free edges were calculated. The results indicate the following behaviors: 1) a longitudinal wave is created at the free edge and propagates along the surface of the plate; 2) a part of the longitudinal wave is transformed to a shear wave at a free boundary parallel to the direction of the wave propagation; and 3) these two waves experience repeated reflections at the free boundaries and thus form a complicated vibration. Transient responses of a rectangular ceramic plate were analyzed next. Prior to the analysis, the vibratory behaviors of the rectangular plate were predicted approximately based on the results for the square plate. The detailed numerical analyses performed could confirm the validity of the predictions.
Low‐drive level characteristics of at‐cut resonators with cylindrical capsules
Authors: Momosaki Eishi , Oomura Yoshimasa 
Published: July 2007

AbstractAs a quartz resonator needed for miniaturizing electronic devices, a rectangular AT‐cut quartz resonator sealed in a cylindrical capsule has been developed and manufactured. It was found that the anomalous characteristics of the resonator at a low‐drive level have something to prevent starting oscillation. The drive level characteristics of the rectangular AT‐cut quartz resonator sealed in a cylindrical capsule have not been clarified to date. These characteristics are obtained from the low‐drive level to the high‐drive level. Among these characteristics, the anomalous phenomena at the low‐drive level (LDL) have been studied experimentally and theoretically. It was found that the anomalous phenomena are caused by the unwanted vibration of the structure other than the resonator plate itself. The frequency of the unwanted vibration depends strongly on the drive level. At the drive level that makes the frequency identical to that of the main resonance, an anomaly occurs in which the frequency and CI jump substantially. The manner of this jump can be calculated by assuming that the unwanted vibration is proportional to the current squared and the coefficient is large. The analysis shows a good agreement with the experimental result. In regard to the unwanted vibration found in the present experiment, it is assumed that the coefficient dependent on the square of the current of the unwanted vibration is negative and that the unwanted vibration is significantly originated in the structures attached to the quartz plate (such as electrodes, support member, mounting material, and dust).
Surface acoustic wave microsensors
Authors: Shiokawa Showko , Kondoh Jun 
Published: July 2007

AbstractIt was found that a surface acoustic wave microsensor is highly sensitive in detecting the physical and chemical changes of the medium on the vibrating surface in real time. Hence, microsensors are used in many applications. There are already several types of surface acoustic wave microsensors with their differences based on vibration and wave modes. New types of sensors are proposed herein and new findings and new applications are reported. The present level of development of surface acoustic wave microsensors is described and these sensors are compared, discussed, and evaluated.Fundamental characteristics are then presented for the shear‐surface acoustic wave (SH‐SAW) microsensors using a 36° rotated Y‐plate X‐propagation LiTaO3 studied by the authors. It is shown that this sensor has many applications. Further, if several SH‐SAW sensors with different frequencies are used, a high recognition rate can be obtained even for liquid samples that cannot be recognized by human perception. The example used here is 13 types of whiskey.
Measuring system for photoresist development parameters
Authors: Sekiguchi Atsushi , Matsuzawa Toshiharu , Minami Youichi 
Published: July 2007

AbstractTo investigate the photoresist development characteristics, a development parameter extracting system for photoresists has been developed utilizing a development rate monitoring system and an exposure parameter measuring system for photoresists. This system is used to obtain the development parameters of a super‐high resolution i‐line photoresist, PFR‐ix500EL (Japan Synthetic Rubber Co., Ltd.), using the development rate equations by Dill, Kim, and Mack. At the same time, the dependence of the simulated profiles on the development rate equations is investigated. Focus latitude for achieving 0.5 μm lines and spaces under the conditions of exposure wavelength of 365 nm, NA = 0.5, and s̀ = 0.6 is evaluated; the simulated and experimental results are compared. It is found that when Mack's equation is used to simulate the development rate, the simulated and experimental results are in good agreement.
Three‐dimensional vector accelerometer using soi structure for high‐temperature use
Authors: Takao Hidekuni , Matsumoto Yoshinori , Ishida Makoto , Nakamura Tetsuro , Tanaka Hidekazu , Seo Hee‐Don 
Published: July 2007

AbstractIn order to improve the high‐temperature reliability of a silicon accelerometer, an accelerometer was fabricated using an SOI substrate and its temperature dependence was compared with that of conventional silicon accelerometers. In addition, the authors attempted to detect the three‐dimensional components of the acceleration vector using a new theoretical principle. The new theoretical principle was validated, and accelerometer design was carried out using a program for structure analysis, ANSYS, which is based on the finite element method (FEM). It was found that, in the accelerometer fabricated using an SOI substrate, the offset voltage and sensitivity at temperatures higher than 200 °C were superior to those in the conventional pn junction device. It was also found that the new device could detect acceleration even at 410°C. Using the new device, the acceleration components in the three directions were accurately measured and the sensitivity for the other axis was suppressed to less than 5.7 percent. The frequency characteristic of the new sensor was in agreement with the theoretical results. Because of high‐temperature operation and detectability of the three directional components of acceleration, this new accelerometer will be much more widely used.
Liquid‐crystal display cell model using piecewise approximations
Authors: Shima Takeshi , Okumura Makiko , Higuchi Toyoki 
Published: July 2007

AbstractThe dynamic characteristics of the capacitance of liquid‐crystal display (LCD) pixel constituting the active matrix LCD device using amorphous thin film transistors (TFTs) have been analyzed; an electrically equivalent circuit model is proposed based on the obtained results. The model consists of nonlinear resistors and dynamic elements such as capacitors or inductors and can represent the voltage and time dependence of the capacitance value in the LCD pixel. The proposed model is incorporated into the circuit simulator SPICE as a built‐in model.
Method of detecting a specific ion by means of crown ethers
Authors: Hirakawa Hiromitsu 
Published: July 2007

AbstractTo replace the conventional ion‐sensitive field‐effect transistor (ISFET) ion sensor, an ion‐sensing method using crown ether was developed. In this method, the alkaline metal ions (Na+ and K+ ions) were detected by the ac potential difference. Crown ether shows selectivity toward alkaline metal ions, forming complexes.To investigate the selective characteristics of crown ethers using the ac potential difference, three types of crown ethers (18C6, 15C5, and 12C4) were used. The solvents used were water, methyl alcohol, acetone, propylene‐carbonate (PC), and dimethyl‐formamide (DMF). Specifically, chlorides (NaCl, KCl, and CsCl) were dissolved in the solvent containing crown ether and the sedimentation potential was measured using a sedimentation‐potential measurement system.When 18C6 was used, the highest sedimentation potential of KCl was observed if PC was chosen for the solvent. When 15C5 was used, the highest sedimentation potential of NaCl was observed if methyl alcohol was used for the solvent. It was confirmed that in order to distinguish K+ and Na+ ions from other ions, PC containing 18C6 and methyl alcohol containing 15C5 should be used, respectively.
A high‐speed 4‐Gsample/s 2‐bit ADC system for radio astronomy
Authors: Matsumoto Kin'Ya , Kawaguchi Noriyuki , Horiuchi Kenji 
Published: July 2007

AbstractIn recent years, the use of very long baseline interferometer (VLBI) devices has increased in the geodesy and radio astronomy communities. To enable these devices to pick out very small variations, it is desirable to increase the sensitivity of the detection of the VLBI. For observing quasars, it is beneficial to increase the observation bandwidth and improve the sensitivity of detection. However, for such wide bandwidth systems, gigahertz‐order sampling high‐speed A/D converters are necessary and the technology for achieving these devices is not yet developed. In this work, we developed, using Si‐bipolar LSI processes (SST‐1B), a 4‐Gsample/s 2‐bit ADC LSI and created a high‐speed ADC system. We evaluated the loss in this system due to phase stability, sampling jitter, and the uncertainty region of the comparator of the LSI to evaluate the coherence of the VLBI. We used a frequency transformer device and a picosecond phase comparator as the measurement device for measuring the phase stability of the gigahertz‐order ADC system. From the measurement results, we determined that the Allen standard deviation over 1‐s of integration time was 3.6 × 10−13, the sampling jitter was 13.4 ps, and the comparator uncertainty was 20 mV. For a wide bandwidth burst mode VLBI observation system with an observation frequency of 230 GHz, a coherence loss of 7.6 percent was observed. We then demonstrated the operation of the ADC system by detecting real radio astronomical observation spectra using this device.
An analysis of the resonance frequencies of stepped, clamped‐free torsional mode resonators and their applications to quartz crystal tuning fork
Authors: Kawashima Hirofumi 
Published: July 2007

AbstractThis paper describes torsional mode quartz crystal resonators of the tuning fork type with stepped vibration bars. A frequency equation and a transcendental equation were derived from the “clamped‐free” boundary condition and the stepped portion of the continuity condition, respectively. Because these equations were given as a function of torsional rigidity, the torsional rigidity was derived from the equation of equilibrium. From related equations, it was shown that high or low frequency could be obtained without a change in length. The calculated results were then compared with the measured values so that both results would be in good agreement.
Integrated optic micropressure sensor using ring resonator
Authors: Ohkawa Masashi , Abe Tetsuharu , Sekine Seishi , Sato Takashi 
Published: July 2007

AbstractIn this paper, sensitivity improvement of integrated optic micropressure sensors is discussed. The sensor is composed of a diaphragm and a ring resonator that is a multiple interference optical circuit. A part of the waveguide of the ring resonator is on the diaphragm. When a pressure is applied to the sensor, the diaphragm is deformed and the refractive index changes slightly so that a phase shift is induced on the guided wave propagating on the diaphragm. From the change of the resonant frequency caused by this phase change, the magnitude of the applied pressure is detected. In this study, particular emphasis is on the relationship between the diaphragm dimensions and the sensor sensitivity. From the analysis of the sensor operation, it is concluded that the use of a square‐shaped diaphragm with a waveguide of the ring resonator at the edge in addition to employing the TM‐like mode is most suited for a highly sensitive sensor. Further, from the evaluation of the minimum detectable pressure, it is expected that an integrated optic microprocessor sensor can be realized which is sensitive to such low pressure as underwater acoustics.
Improved operation of logic devices constructed by asymmetric nonlinear optical fiber couplers using bandwidth limited amplification
Authors: Kojima Takashi , Koshiba Masanori , Tsuji Yasuhide , Eguchi Masashi 
Published: July 2007

AbstractEffects of perturbations including third‐order dispersion on the operation of logic devices constructed by asymmetric nonlinear optical fiber couplers are investigated by using the beam propagation method. In contrast to the unperturbed case, the radiation is stimulated and, consequently, the operation of logic devices is degraded. In order to remove the influence of perturbations, the bandwidth limited amplification is introduced. In a distributed gain medium with a finite bandwidth, the radiation caused by third‐order dispersion may be suppressed and the operation of logic devices is improved.
Analysis of a novel intersection waveguide‐type optical polarization splitter using birefringence of GaInAsP/InP superlattice
Authors: Kambayashi Toshio , Nakasendou Kazuyuki 
Published: July 2007

AbstractA novel intersection waveguide‐type polarization splitter based on total reflection using the birefringence of the GaInAsP/InP superlattice waveguide is proposed and analyzed in this paper. The semivectorial finite difference beam propagation method (FD‐BPM) (which handles both TE and TM modes) is used in the analysis. The waveguide structure including the GaInAsP/InP superlattice is designed; and it is shown that, although with a superlattice core the refractive index for the TM mode is reduced by approximately 0.4 percent, there is no change for the TE mode. Based on this result, the optimal structural parameters such as superlattice layer number, rib height (h), intersecting angle (θ), and port separation length (Lsp) are investigated using a 1.55μm wavelength. It is found that the TE and TM modes can be separated with an insertion loss of less than 0.4 dB for both modes and a crosstalk of less than −35 dB using an intersecting angle of 5° and a device length of approximately 0.9 mm. It is shown that compared to conventional devices, the device length in the proposed device structure can be reduced by using total reflection. The wavelength dependence of the device is also analyzed.