Patent ID: 7598136

Claim:
A method of fabricating an image sensor, comprising: preparing a semiconductor substrate, wherein the semiconductor substrate comprises a pixel area, a resistance area and a CMOS area and wherein the CMOS area comprises an NMOS area and a PMOS area; forming an isolation layer in the semiconductor substrate to define active regions; forming a polysilicon layer on the semiconductor substrate; forming an ion implantation mask pattern on the semiconductor substrate after forming the polysilicon layer, wherein the ion implantation mask pattern covers at least the PMOS area; uniformly doping the polysilicon layer with n-type impurities through the ion implantation mask pattern; removing the ion implantation mask pattern; forming a mask layer on the polysilicon layer after removing the ion implantation mask pattern; patterning the polysilicon layer to form a transfer gate electrode on the pixel area, a resistance pattern on the resistance area, an NMOS gate electrode on the NMOS area, and a PMOS gate electrode on the PMOS area; patterning the mask layer while the polysilicon layer is patterned, thereby forming mask patterns, wherein each mask pattern is aligned with one of the gate electrodes or the resistance pattern; forming a photodiode photoresist pattern on the semiconductor substrate after patterning the polysilicon layer and the mask layer; forming a photodiode in the pixel area using the photodiode photoresist pattern as an ion implantation mask; removing the photodiode photoresist pattern; and removing the mask patterns after removing the photodiode photoresist pattern.