LOW-COST LWIR-BAND CMOS INFRARED (CIR) MICROBOLOMETERS FOR HIGH VOLUME APPLICATIONS

This paper provides an overview of the studies and the current status for the development of a novel, low-cost, and CMOS foundry compatible approach for implementing microbolometers with standard CMOS and simple post-CMOS subtractive MEMS processes. This CMOS infrared detector technology is shortly called as the CMOS IR (CIR) technology, and it can be used to implement Focal Plane Arrays (FPAs) for infrared imaging in the LWIR-band (8-12 mu m wavelength). Post-CMOS processes require only one mask lithography process and simple subtractive etching steps to obtain suspended bulk micromachined microbolometer pixels, where the detector element can be formed with standard CMOS layers and devices such as n-well layers, diodes, polysilicon, and some other CMOS layers and devices. Sensors of various pitch sizes (such as 70 mu m, 60 mu m, 50 mu m, and 35 mu m) and various FPA formats (such as 160x120, 80x80, and 40x40) have been demonstrated; some of these studies resulted in real commercial products in a VC funded spin-off company.