AN UNCOOLED MICROBOLOMETER INFRARED DETECTOR IN ANY STANDARD CMOS TECHNOLOGY

This paper reports a new microbolometer structure with the CMOS n-well layer as the active element. The n-well structures are suspended and thermally isolated by post-etching of fabricated and bonded CMOS chips, while the n-well regions are protected from etching by the electrochemical etch-stop technique in a TMAH solution. The characterization results of the fabricated chips show that the n-well has a TCR value of 0.50%/K at 300K in a commercial 0.8mm CMOS process. Detailed thermal simulations in ANSYS were performed to obtain an optimized structure. These results and calculations show that it is possible to implement a microbolometer structure with a responsivity of 4000 V/W and a detectivity of 1.2x109 cmHz1/2/W with a thermal time constant of 3.2 msec. This approach is very cost-effective to produce large focal plane arrays in CMOS for uncooled infrared imaging with reasonable performance