Integrated Pyroelectric Infrared Sensor Using Pvdf thin Film Deposited by Electro-Spray Method

Abstract

AbstractA pyroelectric infrared sensor using a poly(vinylidene fluoride) (PVDF) thin film has been integrated with a read-out circuit on a silicon substrate. The PVDF thin film with a thickness of 1-2 µm was deposited on the sensing area by an electro-spray (ESP) method. A form I crystal and a large pyroelectric coefficient of 4 nCcm−2K−1 were observed just after the deposition without any poling treatments. The fabrication process of the sensor was based on a standard MOS LSI process and a polysilicon sacrificial layer etching technique. In order to reduce the heat capacitance and the thermal conduction, the PVDF thin film was supported on a thin Si3N4 membrane structure formed by etching a part of the silicon substrate under the sensing area. The sensor with a sensing area of 400x400 µm2 had a responsivity of 98 V/W, a detectivity of l.4× 107 cmHz1/2W−1, an NEP of 2.9× 10−99 Hz1/2W at a frequency of 100 Hz and a time constant of 1.3 msec.