New thermally isolated pixel structure for high-resolution (640 X 480) uncooled infrared focal plane arrays

A new pixel structure with twice-bent beams and eaves structure, suitable for high-resolution uncooled infrared (IR) focal plane arrays (FPAs), is proposed. In comparison with previous results (FPA of 37-mu m pixel pitch), the thermal conductance of the test device with the proposed pixel structure of 23.5-mu m pitch is reduced about 2.5 times. The eaves structure, which is adopted to increase the fill factor of pixels, improves the responsivity by a factor of 1.3. A 640 x 480 bolometer-type uncooled IRFPA is demonstrated by utilizing the new pixel structure, with supplementary modification to improve thermal conductance and thermal time constant. It shows a noise equivalent temperature difference (NETD) of 50 mK for F/1.0 optics at 30 frames/sec, a thermal conductance of 0.03 mu W/K, and a thermal time constant of 16 msec. (c) 2006 Society of Photo-Optical Instrumentation Engineers.