Masahiro YOSHIZAWA Tetsuma SAKURAI Eisuke ARAI
A novel delivery management system using a new lot sampling scheduling (LSS) method has been developed. The method involves the concepts of "virtual line" and "marker lot," and the system consists of an on-line scheduler executing short-period scheduling for lot-tracking and an off-line scheduler executing long-period scheduling for delivery date simulation. The LSS method can hugely increase the maximum number of lots to simulate the delivery date and also control TAT more effectively compared to conventional dynamic scheduling. Lot progress is controlled by varying the resource allocation ratio for each virtual line. This method is effective for precise delivery date control of lots with various priorities in ASIC production or development lines.
Yasuhiro ANDO Shin'ichi IWANO Kazunori KANAYAMA Ryo NAGASE
The statistical properties of insertion losses and return losses for optical connectors are investigated theoretically using the probability theory and the Monte Carlo simulation. Our investigation is focused on an orientation method for reducing insertion loss by which a fiber-core center is adjusted in a region of within a certain angle to the positioning key direction. It is demonstrated that the method can significantly improve insertion losses, and that an adjusting operation angle of 90 degrees is sufficient to realize an insertion loss of less than 0.5 dB with 99% cumulative probability. Good agreement was obtained between the theoretical distribution and the experimental results for single-mode fiber connection. Consequently, it is indicated that the statistical distributions of insertion losses and return losses of optical connectors in the field can be predicted theoretically from the values measured in the factory by connection to a master connector.
Hisako SATO Katsumi TSUNENO Hiroo MASUDA
Recently, high-dose implantation and low temperature annealing have become one of the key techniques in shallow junction formation. To fabricate shallow junction in quarter-micron CMOS VLSIs, it is well known being important to evaluate the transient enhanced diffusion (TED) of implanted dopants at low temperature furnace annealing, which is caused by the damages of implantation. We have newly studied the TED phenomena by a compact empirical method. This approach has merits of simplicity and better physical intuition, because we can use only minimal parameters to describe the TED phenomena. The other purpose of this work is to evaluate two-dimensional transient enhanced diffusion focusing on phosphorus implant and furnace annealing. Firstly, we defined effective diffusivity of the TED and determined extraction procedure of the model parameters. Number of the TED model parameters is minimized to two, which describe effective enhanced diffusivity and its activation energy. The parameters have been extracted from SIMS profile data obtained from samples which range 1013-31015 cm-2 and 850-950 for phosphorus implanted dose and annealing temperature, respectively. Simulation results with the extracted transient enhanced diffusion parameters show good agreements well with the SIMS data within 2% RMS-error. Critical doses for phosphorus enhanced diffusion have been determined in 950 annealing condition. No transient enhanced diffusion is observed at 950 under the implant dose of 11013 cm-2. Also the transient enhanced diffusivity is leveled off over the dose of 11014 cm-2. It is seen that the critical dose in TED phenomena might be temperature dependent to a certain extent. We have also verified that two-dimensional effect of the TED phenomena experimentally. Two-dimensional phosphorus n- layer is chosen to verify the simulation. It was concluded that the TED has isotropic nature in phosphorus n- diffusion formation.
In the present paper, we focus ourselves on the turning point (TP) algorithm proposed by Mueller and evaluate its performance when applied to a Gaussian signal with definite covariance function. Then the ECG wave is modeled by Gaussian signals: namely, the ECG is divided into two segments, the baseline segment and the QRS segment. The baseline segment is modeled by a Gaussian signal with butterworth spectrum and the QRS one by a narrow-band Gaussian signal. Performance of the TP algorithm is evaluated and compared when it is applied to a real ECG signal and its Gaussian model. The compression rate (CR) and the normalized mean square error (NMSE) are used as measures of performance. These measures show good coincidence with each other when applied to Gaussian signals with the mentioned spectra. Our results suggest that performance evaluation of the compression algorithms based on the stochastic-process model of ECG waves may be effective.
Nobutaro SHIBATA Yoshinori GOTOH Shigeru DATE
New memory-macrocell architecture has been developed to obtain high-performance macrocells with a short design Turn-Around-Time (TAT) in ASIC design. The authors propose row- and column-sliceable macrocell architecture in which only nine kinds of rectangular-functional cells, called leaf-cells, are abutted to form macrocells of any sizes. The row-sliceable structure of peripheral circuits is possible due to a newly-developed channel-embedded address decoder combined with via-hole programming. Macrocell performance, especially access time, is kept at a high level by the distributed driver configuration. Zero address-setup time during write operation is actualized by delaying internal write timing with a new delay circuit. A short design TAT of 30 minutes is accomplished due to the simplicity of both macrocell generation and the checking procedure. The macrocells are designed with gate-array and full-custom style, and fabricated with 0.5 µm CMOS technology.
Toshiyuki TSUCHIYA Takashi SHIRAISHI Junro ARATA
A fiber-optic transmission system for linking radio base stations to the mobile communication center is developed, and its performance is evaluated. The introduction of this system yields two main improvements: optimum zone allocation to increase radio frequency utilization efficiency and the elimination of service quality issues such as dead zones and traffic imbalance. Being optical, the system suffers from the interferometric noise and distortion created by multiple reflections within the fiber. Moreover, because system response is much different from that of optical CATV systems, we clarify the optical parameter selection criteria and hypothetical return loss model for an embedded fiber infrastructure. An optical multiplexing method is also introduced that reduces the quantity of fiber and connectors, as well as splicing and cable installation costs. A new ternary optical multiplexing architecture combined with a cost-effective self-tuning type WDM technique and a high isolation type circulator are proposed for the 1.3µm wavelength region. The performance of low distortion high power common amplifiers is measured with the aim of reducing the size and weight of back-up batteries, and to improve the packaging density of the typical base station.
Intermittent chaos was observed in the silicon thyristor circuit without external elements of L and C, under the condition of ac excitation at the anode. Lorenz plot reconstructed from the experimental waveform and the numerical simulation of this kind of intermittency fairly agreed with each other.
Koji KOTANI Tadahiro OHMI Satoshi SHIMONISHI Tomohiro MIGITA Hideki KOMORI Tadashi SHIBATA
Self-aligned aluminum-gate MOSFET's have been successfully fabricated by employing ultraclean ion implantation technology. The use of ultra high vacuum ion implanter and the suppression of high-energy ion-beam-induced metal sputter contamination have enabled us to form ultra-shallow low-leakage pn junctions by furnace annealing at a temperature as low as 450. The fabricated aluminum-gate MOSFET's have exhibited good electrical characteristics, thus demonstrating a large potential for application to realizing ultra-high-speed integrated circuits.
As the values of parameters in periodic systems vary, a nodal point appearing on a locus of period doubling bifurcation points crosses over a locus of turning points. We consider the nodal point lying just on the locus of turning points and consider its accurate location. To compute it, we consider an extended system which consists of an original equation and an additional equation. We present a result assuring that this extended system has an isolated solution containing the nodal point.