Method for forming backside illumination cmos image sensor

Abstract

The present disclosure provides a method for forming a backside illumination CMOS image sensor, including: providing a first substrate having a first surface and a second surface opposite to each other; forming a photoelectric epitaxial layer on the second surface, wherein the photoelectric epitaxial layer has a third surface and a fourth surface opposite to each other, and the second surface is adjacent to the third surface, wherein the photoelectric epitaxial layer is includes a groove extending from the fourth surface to the third surface, and the photoelectric epitaxial layer includes a plurality of first doped areas and a plurality of second doped areas surrounding the plurality of first doped areas respectively; forming a device layer after forming the groove and the photoelectric epitaxial layer; and forming an isolation layer in the groove. The method can reduce generation of dark current and improve performance of the CMOS image sensor.