Image Sensor with Improved Dark Current Performance

A method of fabricating a semiconductor device, comprising:

• providing a substrate having a front side and a back side, the substrate having radiation-sensing elements disposed in a first region of the substrate;
• thinning the substrate from the back side;
• forming a first compressive layer over the back side of the substrate;
• forming a light shield over a selected portion of the first compressive layer;
• and
• forming a second compressive layer over the first compressive layer and over the light shield.

A semiconductor image sensor device, comprising:

• a semiconductor substrate having a front side and a back side, the substrate including an array region and a black level correction region, wherein the array region contains a plurality of radiation-sensitive pixels proximate the front side, and the black level correction region contains one or more reference pixels proximate the front side;
• a first compressively-stressed layer formed on the back side of the substrate, the first compressively-stressed layer containing silicon nitride;
• a metal shield formed on the compressively-stressed layer, wherein the metal shield is formed over at least a portion of the black level correction region;
• and
• a second compressively-stressed layer formed on the metal shield and the first compressively-stressed layer, wherein the second compressively-stressed layer contains silicon oxide, and wherein a sidewall of the metal shield is protected by the second compressively-stressed layer.