Patent ID: 7388187

Claim:
An image sensor device, comprising: a semiconductor substrate having a first type of conductivity; a semiconductor layer, having the first type of conductivity, formed on the semiconductor substrate; a plurality of shallow trench isolation (STI) features formed in the semiconductor layer, wherein each of the plurality of STI features is disposed between the plurality of pixels; a plurality of guard-ring wells having the first type of conductivity, wherein each of the plurality of guard-ring wells substantially underlies each of the plurality of STI features; and a plurality of pixels formed in the semiconductor layer, wherein the plurality of pixels include at least one photodiode; wherein the semiconductor layer comprises a first deep well having the first type of conductivity, and substantially underlying the plurality of pixels and directly underlying the at least one photodiode, and a second deep well having a second type of conductivity different from the first type of conductivity and substantially underlying the first deep well.