Image sensor with epitaxial sealing layer for front-side deep trench isolation and manufacturing method thereof

Abstract

A method includes forming a doped region in a substrate; forming a doped well vertically extending from a front side of the substrate into the doped region; forming a transfer gate over the front side of the substrate and laterally between a first portion of the doped well and a second portion of the doped well; forming a trench vertically extending form the front side of the substrate through the doped well toward a back side of the substrate; depositing an dielectric material over the front side of the substrate and in the trench; recessing the dielectric material; performing a selective epitaxial growth process to form a sealing layer in the trench and over the recessed dielectric material from the front side of the substrate; forming an electrode in the trench and over the sealing layer from the front side of the substrate.