640 x 480 17 um microbolometer uncooled detector development at ASELSAN, Inc.

Microbolometer detectors have drawn attention due to their advantages such as small dimensions, light weight, low power consumption and no cooling requirement. In recent years, studies regarding the microbolometers have accelerated. Research on uncooled infrared microbolometer detectors was initiated at ASELSAN in 2014. As result of these activities, microbolometers with high TCR and low 1/f noise level have been achieved based on vanadium oxide active material. Pixel structures with high fill factor ratios are accomplished using double layer pixel architecture and high responsivity values were obtained by FPA optimizations. 640 x 480 format and 17 μm pixel pitch microbolometer FPAs along with VO_x sensing layer were produced. These detectors have demonstrated state of the art NETD values (< 30 mK @ f/1) and with such properties that could be used in various applications which require high frame rates due to their low time constant values (< 12 ms). FPA fabrication has been performed on 8” CMOS ROIC wafers which are also designed by ASELSAN. 17 μm pixel pitch 640 x 480 format ROIC has been developed for resistive microbolometer detector arrays. ROIC wafers were fabricated using 0.18 μm CMOS process where 3.3 V analog and 1.8 V digital supplies are used. The ROIC has 4 analog video outputs and 2 analog reference outputs. It can be operated at 1, 2 or 4 output modes depending on the frame rate requirement. In 2-output mode of operation power consumption of the ROIC is less than 150 mW. In this paper, the details of the microbolometer detectors including the ROIC design, vacuum packaging and detector performances are presented.