Backside illuminated image sensor and method of manufacturing the same

A backside illuminated image sensor comprising:

• a plurality of pixel regions disposed in a substrate;
• an insulating layer disposed on a frontside surface of the substrate;
• a bonding pad disposed on a frontside surface of the insulating layer;
• and
• an anti-reflective layer disposed on a backside surface of the substrate, wherein:
• the substrate defines a first opening that at least partially exposes a backside surface of the insulating layer,
• the insulating layer defines a third opening that at least partially exposes a backside surface of the bonding pad, the third opening defining an inner side surface thereof,
• the anti-reflective layer comprises a first portion disposed on an inner side surface of the first opening and a second portion disposed on a portion of the backside surface of the insulating layer exposed by the first opening and defining a second opening arranged between the first opening and the third opening, the second opening defining an inner side surface thereof, and
• a first spacer is disposed on the inner side surfaces of the second opening and the third opening.