Patent ID: 8785984

Claim:
A backside illuminated image sensor comprising: a substrate having a front surface and a back surface, wherein the back surface is a light receiving surface; a polysilicon layer formed on the substrate; a first doped region formed within the substrate; and a second doped region formed within the substrate over the first doped region such that the first doped region is nearer to the light receiving surface of the substrate than the second doped region, wherein the second doped region is formed to have an overlap of only a portion of the polysilicon layer, wherein the first doped region reaches to a depth of greater than 50 percent of a thickness of the substrate such that a distance between the light receiving surface of the substrate and the first doped region is less than 50 percent of the thickness of the substrate; wherein the second doped region extends from a top surface of the substrate into at least a portion of the first doped region; and wherein the first and second doped regions have a first type conductivity.