Patent ID: 8772898

Claim:
A backside illuminated image sensor comprising: a semiconductor layer having a frontside surface and a backside surface, the semiconductor layer including: a light sensing element of a pixel array disposed in a sensor array region of the semiconductor layer, wherein the pixel array is positioned to receive external incoming light through the backside surface of the semiconductor layer; and a light emitting element disposed in a periphery circuit region of the semiconductor layer external to the sensor array region, wherein the periphery circuit region includes circuit elements that facilitate operation of the light sensing element; a trench disposed in the semiconductor layer between the light sensing element and the light emitting element, the trench positioned to impede a light path between the light emitting element and the light sensing element, wherein the light path is internal to the backside illuminated image sensor; and an anti-reflection coating layer disposed in the trench and along sidewalls of the trench, but not completely filling the trench.