Kouji Inoue

Chopperless-operated dielectric bolometer mode of infrared image sensor with ferroelectric BST film using improved operation

Proposes a new type of simple detector pixel circuit and device structure for application of dielectric bolometer mode (DB) of IR image sensor, which has merits in uncooled operation, chopperless operation, low power dissipation, and high-sensitivity. We have successfully developed techniques of supply-voltage to the detector and a stable Ba/sub 1-x/Sr/sub x/TiO/sub 3/ (BST) thin film with large temperature coefficient of dielectric constant (TCD) as an IR detecting material, in order to stabilize the output level and improve the IR sensitivity. Also, a stress-balanced membrane for thermally isolated structure as an IR detector and resultant sensor arrays monolithically integrated with Si readout were developed. As a result, the stabilities in both TCD and output level have significantly improved and enabled us to obtain a fairly large IR detectivity, where best R/sub v/ and D* were about 1.2 kV/W and 2.9 /spl times/ 10/sup 8/ cmHz /sup 1/2//W, respectively.

SiO2 film growth by double-excitation photo-CVD using Si3H8 and O2

Abstract Silicon dioxide thin films have been grown at low temperatures from 25 to 390 ° C from Si3H8 and O2 gases by double-excitation photo-CVD using VUV light from a D2 lamp and UV light from a Hg lamp. Growth rate of the films grown at flow rate ratio Si3H8/O2=0.17 is ≌150 A/min at 25 ° C and decreases as the substrate temperature increases. The refractive index has a maximum of 1.452 in the film deposited at 160 ° C and decreases for temperatures lower or higher than 160 ° C. The amount of Si-H and Si-OH, and the fixed-oxide-charge decrease as the temperature increases. The film deposited at 260 ° C shows a minimum interface state density of 3.6x1010 cm-2 eV-1 near the midgap.

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.

Fabrication of sonic sensors using PZT thin film on Si diaphragm and cantilever

Micro sonic sensors with a high quality factor (Q-value) using piezoelectric diaphragm and cantilever have been developed for detecting a specific sonic wave which is emitted due to anomalous behavior of rotary machines such as turbines, motors and engines. A piezoelectric PbZr/sub 0.52/Ti/sub 0.48/O/sub 3/ thin film was prepared on a micromachined SOI wafer by sol-gel method. The dependence of the output voltage of the both diaphragm- and cantilever-sensors on the sonic frequency was examined. The both sensors were found to have resonant peaks in the frequency region over 5 kHz with a high Q-value (>100), and the typical sensitivity for the sonic wave at the resonant frequency was estimated to be 10 mV/Pa, which is comparable to that of a commercial bulk ceramics sensor.