Abstract
P(VF2-TrFE) pyroelectric copolymer is chosen for its high level of compatibility with existing microelectronics processes, and convenient electrical properties for infrared (IR) 8 to 14 micrometer imagery in the performance range of NETD 0.1 K to 1 K. Low cost sensors, achievable thanks to the monolithic silicon wafer processing, standard package assembly, and uncooled operations, allow us to address a lot of low-end applications in which conventional IR imaging techniques -- high priced hybrid mercury cadmium telluride or indium antimonide arrays, liquid nitrogen cooling and sophisticated image processing -- are nowadays incompatible with large volume user's needs and market prices. The paper describes pyroelectric device trade-offs, architecture, and process. Based on the interline architecture, the sensor performances of the TH 7441A 128 by 128 area array infrared detector are presented: compatible with 1 inch optics, the square array is made of an 80 by 80 micrometer squared pixel, on a pixel pitch of 85 micrometer. The CCD multiplexer using patented on-site processing is designed to deliver the image information at the maximum rate of 50 image/s. Lower rates are achievable. Imaging performances are the following: a NETD of 1.7 K is achieved with an integration time of 10 ms and the use of a f/1 optics presenting a transmission of 0.8. Recent improvements in the properties of the pyroelectric sandwich include thermal insulation of the pyroelectric layer through mixed air-polyimide material and pixel side to side insulation. Thanks to on-wafer pixel reticulation, an increased modulation transfer function of 51% at Nyquist frequency is achieved.
