Monolithic and hybrid backside illuminated active pixel sensor arrays

摘要

Two types of backside illuminated CMOS Active Pixel Detectors-optimized for space-borne imaging-have been successfully developed: monolithic and hybrid. The monolithic device is made out of CMOS imager wafers post-processed to enable backside illumination. The hybrid device consists of a backside thinned and illuminated diode array, hybridized on top of an unthinned CMOS read-out. Using IMEC's innovative techniques and capabilities, 2-D arrays with a pitch of 22.5 μm have been realized. Both the hybrid and well as the monolithic APS exhibit high pixel yield, high quantum efficiency (QE), and low dark current. Cross-talk can be reduced to zero in the hybrid sensors utilizing special structures: deep-isolating trenches. These trenches physically separate the pixels and curtail cross-talk. The hybrid imagers are suitable candidates for advanced "smart" sensors envisioned to be realized as multi-layer 3D integrated systems. The design of both these types of detectors, the key technology steps, the results of the radiometric characterization as well as the intended future developments will be discussed in this paper.