Backside illuminated SPAD image sensor with 7.83mm pitch in 3D stacked CMOS technology
We present the first 3D stacked backside illuminated (BSI) single photon avalanche diode (SPAD) image sensor capable of both single photon counting (SPC) intensity, and time resolved imaging. The 128x120 prototype has a pixel pitch of 7.83 mm making it the smallest pixel reported for SPAD image sensors. A low power, high density 40nm bottom tier hosts the quenching front end and processing electronics while an imaging specific 65nm top tier hosts the photo detectors with a 1 to 1 hybrid bond connection [1] The SPAD exhibits a median dark count rate (DCR) below 200cps at room temperature and 1V excess bias, and has a peak photon detection probability (PDP) of 27.5% at 640nm and 3 V excess bias.
2016 IEEE International Electron Devices Meeting (IEDM)