TSMC Proposes Stacked BSI Process

TSMC patent application US20130020662 "Novel CMOS Image Sensor Structure" by Min-Feng KAO, Dun-Nian Yaung, Jen-Cheng Liu, Chun-Chieh Chuang, and Wen-De Wang presents a stacked sensor process. 3 wafers are bonded together in a single stack: a BSI sensing wafer 30, a circuit and interconnect wafer 270+360, and a carrier wafer 400:

TSMC Stacked Sensor (features not in scale)