Uncooled Bolometer FPA Intrusion Detector

A new class of infrared uncooled focal plane arrays (UFPAs) has emerged using resistive microbolometers as longwave infrared (LWIR) detectors. In a resistive bolometer, absorbed infrared energy produces a temperature change in a thermally isolated thermal detector. A high temperature coefficient of resistance bolometers using deposited films of vanadium oxide achieve a moderate TCR of 2%/degrees C. We propose to use thermally isolated amorphous silicon as the microbolometer LWIR thermal detector capitalizing on its high temperature coefficient in excess of 12%/degrees C. In addition, a UFPA based upon an all silicon integrated circuit process can be fabricated at commercial silicon integrated circuit foundries. Integrated circuit micro-machining processes will be used to produce a low thermal mass island of amorphous silicon on a self supporting bridge which provides thermal isolation. The resultant all silicon UFPA formed by this process offers the potential to construct thermal imaging systems of high cosmetic quality, higher performance and lower cost than existing hybrid pyroelectric and monolithic bolometric FPA approaches.