Patent ID: 9515116
Filing Date: 2016-12-06
CPC Classification: H01L

Claim Text:
1. A back side illumination (BSI) image sensor comprising: a semiconductor column extending vertically from a photodetector, towards a back-end-of-line (BEOL) stack; a T-shaped floating diffusion region (FDR) vertically spaced from the photodetector by the semiconductor column, wherein the T-shaped FDR comprises a sidewall surface laterally offset from a neighboring sidewall surface of the semiconductor column to define a lateral recess between the T-shaped FDR and the photodetector; a gate dielectric layer lining the sidewall surface of the semiconductor column and arranged in the lateral recess; a gate arranged laterally adjacent to the gate dielectric layer and filling the lateral recess, wherein the gate comprises a metal gate liner layer confined to the lateral recess and lining the lateral recess, wherein the gate further comprises a metal gate filler layer filling the lateral recess, and wherein the T-shaped FDR overhangs the gate; and an etch stop layer interposed between the gate and a lower surface of the T-shaped FDR within the lateral recess.