Mitsuharu Takigawa

Integrated piezoresistive pressure sensor with both voltage and frequency output

Abstract An on-chip integrated piezoresistive pressure sensor with both voltage and frequency outputs has been developed. The sensor chip, having a size of 3 × 3.8 mm 2 , was realized by the use of a standard bipolar IC process. The output voltage span is 1 to 4 V for a pressure range of 0 to 750 mmHg. The pressure sensitivity of the voltage output is 4 mV/mmHg. The non-linearity is less than 0.4 % of the full scale. The sensitivity of the frequency output is about 30 kHz for a 750 mmHg change in pressure. The output is in the T 2 L level. The temperature coefficient of the sensitivity is less than 0.06%/°C in the temperature range −20 to 110 °C.

Micro-diaphragm pressure sensor

A micro-diaphragm pressure sensor with silicon nitride diaphragm of 80 µm × 80 µm was fabricated by applying micromachining technique. The main feature is that it is a complete planar type pressure sensor formed by single-side processing solely on the top surface of

Control of internal stress and Young’s modulus of Si3N4 and polycrystalline silicon thin films using the ion implantation technique

Boron and phosphorus ions are implanted in order to control the internal stress and Young’s modulus of 200‐nm‐thick silicon nitride and polycrystalline silicon films prepared by low‐pressure chemical vapor deposition. These ions are implanted into the middle layer of the films at doses of 1×1014 and 1×1015/cm2, then the films are annealed at 900 °C. The internal stress and Young’s modulus of these films are measured by a rectangular membrane load deflection technique [Tech. Digest, IEEE Micro Electromechanical Systems Workshop, IEEE, Salt Lake City, UT, 1989, p. 152]. Both internal stress and Young’s modulus of the silicon nitride film decrease with dose, while those of the polycrystalline silicon film do not necessarily decrease.

Very High Speed Static Induction Thyristor

Characteristics of a newly developed static induction thyristor (SIThy) are described. The SIThy is irradiated by 2-MeV protons to improve the switching speed as a result of local carrier lifetime control. The characteristics of the proton irradiated SIThy are controlled by annealing conditions to obtain devices for various applications. The switching speed of the SIThy is very high; for example, at an anode current of 50 A, its rise time, storage time, and fall time are 100 ns, 60 ns, and 50 ns, respectively. Thus the newly developed SIThy is suitable for high-speed switching devices.

High temperature operated enhancement-type β-SiC MOSFET

Enhancement-type β-SiC MOSFETs have been fabricated on a single crystalline β-SiC layer grown on a 3-inch Si(100) substrate by chemical vapor deposition. The MOSFETs fabricated by applying the reactive ion etching technique show reasonable I-V characteristics at room temperature. The saturation tendency of the drain currents has been observed at a drain voltage as high as 18 V. The MOSFETs operate even at 350°C.

Impedance spectroscopy on YSZ with iron oxide as additive

Abstract Doping effect of iron-oxide to YSZ (9 mol% yttria) on its electrical properties has been studied by impedance spectroscopy technique. The separation of bulk resistance (Rb), grain boundary resistance (Rgb) and electrode resistance (Re) was made easier when the impedance data were plotted in the complex plane. A parallel circuit of Rgb and Cgb, which corresponds to the capacitance of the grain boundary, gives a semicircle as a first approximation. The shape of Rgb versus ion oxide content curve is similar to that of Egb (the activation energy of the grain boudary curve). On the other hand, shape of Cgb curve correlates to change of Eb, which is the activation energy for the bulk resistivity. These results can be explained in terms of an accumulation of carrier species in the grain boundary.

A simplified serial communication network within a vehicle

The authors propose a simplified serial communication network that is designed to perform real-time control in a distributed function system within a vehicle. The network has a ring type structure and the data transfer rate is 1 Mbit/sec. The network interface circuit is realized in a small gate size and is built in a communication interface circuit of microprocessors or intelligent sensors of smart power ICs. The communication network is controlled by a communication controller whose gate size is about 300 gates. The network system is applied to a distributed function engine control system with six CPUs (central processing unit) connected with sensors and power devices for engine idle speed control of lean burn processes. The engine control system is shown to function successfully. The deviation of engine speed was less than 10 r.p.m. when engine idle speed was 550 r.p.m. and the airfuel ratio was 19.<<ETX>>

Low-loss high-power static induction thyristors for complementary circuits

Two techniques are proposed to obtain low-loss high-power static induction thyristors (SIThys). A dual-sided proton-irradiation technique and a technique that combines anode shorting and proton irradiation both provide n-channel and p-channel SIThys with high blocking voltages and a good trade-off between switching times and forward voltage drops. In particular, dual-sided proton irradiation provides a SIThy with forward and reverse blocking voltage higher than 1 kV. An n-channel SIThy with an n-region thickness of 230 mu m has shown a rise time of 0.24 mu s, a storage time of 0.19 mu s, a fall time of 0.08 mu s, and a forward voltage drop of 3.0 V at an anode current of 50 A (125 A/cm/sup 2/). The effect of the combined technique is much the same as that of the dual-sided proton irradiation. Using the dual-sided proton irradiation, a p-channel SIThy with a p-region thickness of 430 mu m has shown a rise time of 0.5 mu s, a storage time of 0.1 mu s, a fall time of 0.3 mu s, and a forward voltage drop of 6.0 V at an anode current of 4 A (110 A/cm/sup 2/). Using the proposed techniques, a complementary high-power control circuit with low loss and switching frequency higher than a few hundred kilohertz can be realized. >

Fabrication of MOSFETs on β-SiC Single Crystalline Layers Grown on Si(100) Substrates

High temperature semiconductor devices are desirable for electronic control systems in automobiles. Silicon carbide is a promising semiconductor material for this purpose, because of its wide bandgap and physical stability[l]. Many devices fabricated in silicon carbide material have been reported[2–6]. Recently, a depletion-mode MOSFET, operating at 650°C, was reported by Palmour et al.[7]; this report demonstrates the high temperature capabilities of SiC devices.

High-performance SI-thyristor and its application to PWM inverter

A high-performance static induction thyristor (SIT) has been fabricated using a proton irradiation technique. The SIT had extremely high switching speed(t/sub r/=200 ns, t/sub stg/=200 ns, and t/sub f/=60 ns at 400 V, 100 A) and high current control capability (>or=1600 A/cm/sup 2/). The application of the SIT to a pulsewidth-modulated (PWM) inverter with a carrier frequency of 15 kHz is reported.<<ETX>>