Patent ID: 7423306

Claim:
A pixel for CMOS image sensor device, comprising: a substrate comprising a first well region formed in a top portion of the substrate, having a first conductivity type and a first doping concentration; a plurality of shallow trench isolation (STI) structures formed in the first well region, defining at least one pixel region over the substrate; a second well region formed in a potion of the first well region of the pixel region, having a second conductivity type opposite to the first conductivity type; a top surface region formed in a top portion of the second well region, having the first conductivity type and a second doping concentration; and a MOS transistor formed on portions of the pixel region, having a pair of source/drain regions formed in the first well region, wherein the source/drain regions are formed of the second conductivity type and one of the source/drain regions physically connects the second well region and the top surface region, and the second well region is formed with a depth greater than that of the STI structure adjacent thereto.