M. Okuyama

Tactle array sensor with inclined chromium/silicon piezoresistive cantilevers embedded in elastomer

Tactile array sensor of the micro-cantilevers embedded in the elastomer has been fabricated to detect normal and 2-axes shear stresses. It is demonstrated that tactile array sensor with 3 × 3 detective elements can be fabricated with excellent yield. The sensor element is sensitive to both normal and shear stresses applied on entire sensor surface. Moreover, it has good directional characteristics so that it is shown that magnitude and direction of shear stress can be obtained by difference of output voltages of adjacent sensor cantilevers. The sensor output has good reproducibility for multiple measurement. The output from sensor element drastically changes with shifting applying position of force. It is considered that we can obtain pressed position from distribution of output from sensor element array.

Diaphragm stress control for sensitivity improvement of piezoelectric ultrasonic microsensors on silicon dioxide diaphragms

Piezoelectric ultrasonic microsensors have been fabricated using sol-gel derived PZT (Pb(Zr,Ti)O3) thin films on micromachined silicon dioxide diaphragms made from a normal silicon wafer instead of the conventional SOI (silicon on insulator) wafer process. The layered structure of the PZT capacitor part on the diaphragm has been modified in order to control the total lateral stress in the diaphragm for sensitivity enhancement. The sensors having an island-like structure in the PZT layer have shown over 2 times higher sensitivity than conventional sensors.

Development of a Capacitive Ultrasonic Sensor Having Parylene Diaphragm

The present paper reports the development of a capacitive ultrasonic sensor having Parylene diaphragm. Parylene diaphragm is flexible and non-brittle, allowing good sensitivity and durability. The resonant frequency under the tensile stress of Parylene and the influence of the number and the radius of acoustic holes on damping ratio are investigated by FEM simulation. Practical sensor devices are fabricated. They can receive an impulsive ultrasonic pulse transmitted by a spark discharge. The ranging system using this sensor can detect the distance up to 1 m with the error less than 1 mm. The developed sensor can be approximated to be non-directional.

RF-sputtered BST film microwave tunable device on comparison between MgO(111) and (100) substrate

We have increased sufficiently figure-of-merit of (Ba,Sr)TiO3(BST) film microwave tunable device by a few times in frequency range of 20 GHz on MgO(111) from that on MgO(100) substrate. Also found the possibility that it is deeply related to the difference in the film strain.

Preparation by pulsed laser deposition and characterization of ZrO/sub 2/, HfO/sub 2/ and PrO/sub x/ thin films for high-k gate insulator

High-k thin films of ZrO/sub 2/, HfO/sub 2/ PrO/sub x/ of /spl sim/10 nm thickness have been prepared by pulsed laser deposition (PLD), and characterized in microscopic structure and electrical properties. Crystallization is promoted in ZrO/sub 2/ films deposited above 400/spl deg/C, but a significant XRD peak was not observed in the ZrO/sub 2/ film grown below 400/spl deg/C. Moreover, density of the film is confirmed to saturate above 400/spl deg/C by grazing incident angle X-ray reflectance. The leakage current is decreased by increasing growth temperature, but an equivalent-oxide thickness (EOT) obtained from accumulation capacitance of C - V characteristics becomes large. HfO/sub 2/ films show the similar behaviors to ZrO/sub 2/ films. The films deposited at 400/spl deg/C were annealed at 400/spl deg/C in O/sub 2/ gas to reduce the leakage, but the EOTs become large. So, these films were irradiated with oxygen radical at the pressure of 10/sup -3/ Pa both to prevent the growth of interfacial layer and to enhance the oxidation of only the films. Although the leakage of ZrO/sub 2/ films can be reduced by oxygen radical irradiation, only small improvement is observed in the PrO/sub x/ films.