High resolution SXGA InSb detector for long range sights

Abstract

Large format high resolution FPAs are the key elements for medium to high performance applications including enhanced vision, thermal sights, and industrial applications. In this work, the characteristics of recently developed 10 μm pitch SXGA InSb detector are presented. To develop the 10 μm pitch SXGA InSb detector, three important technical issues were resolved. At first, physically isolating pixels to reduce the crosstalk was adopted to enhance the Modulation Transfer Function (MTF). It was found that the MTF of fabricated detector tested with slanted edge method was improved largely. The MTF of 10 μm pitch FPAs at the Nyquist frequency showed the same MTF of 15 μm pitch device at the Nyquist frequency. Therefore the zoomed image of 10 μm pitch device will have the same image quality as the 15 μm device. Another important issue is the indium bump fabrication process. To fabricate fine bump with uniform height, electrodeposition technology was developed. With this method, uniform indium bump over the 8' ROIC could be achieved. Finally, to achieve large capacitance, 0.18 μm CMOS technology was adopted. To use 0.18 μm CMOS technology, the ROIC should have to be designed all again. The designed and fabricated ROIC has 2.4 Me- with 3.3 V bias voltage and has 8 output channels with 20 MHz output rate. The developed 10 μm pitch InSb SXGA detector showed median NETD (Noise Equivalent Temperature Difference) of 22.6 mK. To measure the stability of developed 10 _m pitch InSb SXGA detector, system NETD(SNETD) was measured after thermal cycling. The SNETD of 30 mK was measured for more than 200 thermal cycling, which shows that the output of developed FPA is very stable.