Patent ID: 8890273

Claim:
A semiconductor device, comprising: a semiconductor substrate having a pixel array area comprising a plurality of photosensors disposed in the substrate, the photosensors being formed along a front side surface of the semiconductor substrate, one of the photosensors corresponding to each pixel in the pixel array area; and an optical grid on the backside of the semiconductor substrate and bounding each of the pixels in the pixel array area, wherein the optical grid further comprises: a base material; a pure metal coating over the base material, the pure metal coating being at least 99% pure metal; and a high-k dielectric material over the pure metal coating, the high-k dielectric material having a refractive index greater than 2.0, wherein each of the base material, the pure metal coating, and the high-k dielectric material are patterned to have a grid pattern on the backside of the semiconductor substrate, and wherein the pure metal coating completely covers sidewalls of the grid pattern of the base material.