IMAGE SENSOR AND METHOD OF FORMING THE SAME

The present disclosure describes a three-chip complementary metal-oxide-semiconductor (CMOS) image sensor and a method for forming the image sensor. The image sensor a first chip including a plurality of image sensing elements, transfer transistors and diffusion wells corresponding to the plurality of image sensing elements, a ground node shared by the plurality of image sensing elements, and deep trench isolation (DTI) structures extending from the shared ground node and between adjacent image sensing elements of the plurality of image sensing elements. The image sensor further includes a second chip bonded to the first chip and including a source follower, a reset transistor, a row select transistor, and an in-pixel circuit, where the source follower is electrically coupled to the diffusion wells. The image sensor further includes a third chip bonded to the second chip and including an application-specific circuit, where the application-specific circuit is electrically coupled to the in-pixel circuit.