Stacked cmos image sensor with sti-free photodetector isolation and method for forming the same

Abstract

Various embodiments of the present disclosure are directed towards a stacked complementary metal-oxide semiconductor (CMOS) image sensor in which a pixel sensor spans multiple integrated circuit (IC) chips and is devoid of a shallow trench isolation (STI) structure at a photodetector of the pixel sensor. The photodetector and a first transistor form a first portion of the pixel sensor at a first IC chip. A plurality of second transistors forms a second portion of the pixel sensor at a second IC chip. By omitting the STI structure at the photodetector, a doped well surrounding and demarcating the pixel sensor may have a lesser width than it would otherwise have. Hence, the doped well may consume less area of the photodetector. This, in turn, allows enhanced scaling down of the pixel sensor.