Patent ID: 8614113

Claim:
A method for fabricating an image sensor, comprising: forming a first insulating layer on a semiconductor epitaxial layer having a plurality of pixel regions; patterning a portion of the semiconductor epitaxial layer and the first insulating layer in a boundary region between the pixel regions to form a trench; forming a buried insulating layer on the first insulating layer, filling the trench, the buried insulating layer having a planar top surface; forming a second insulating layer on the buried insulating layer; forming a first mask pattern on the second insulating layer, the first mask pattern defining an opening overlapping the trench; performing a first ion implantation process using the first mask pattern as a first ion implantation mask to form a first conductivity type of potential barrier region in the semiconductor epitaxial layer beneath the trench; widening the opening in the first mask pattern; and performing a second ion implantation process using the first mask pattern with the widened opening as a second ion implantation mask to form a first conductivity type of side potential barrier region in the semiconductor epitaxial layer laterally adjacent sides of the trench.