Patent ID: 7179675

Claim:
A method for fabricating an image sensor comprising: forming a first seed layer on a semiconductor substrate; forming a second seed layer on the first seed layer, wherein the second seed layer is a first polysilicon layer; forming a blocking layer on the second seed layer; partially exposing a region for a transistor corresponding to an active region of the semiconductor substrate by patterning the first seed layer, the second seed layer, and the blocking layer; growing a gate insulating material layer in a portion of the exposed region by selective thermal oxidation of the first seed layer, the second seed layer, and the semiconductor substrate; filling a gate electrode material layer in the exposed region over the gate insulating material layer; forming a gate insulating layer pattern and a gate electrode pattern by selectively removing the blocking layer, the gate insulating material layer, the gate electrode material layer, and the first seed layer; the second seed layer and forming source and drain diffusion layers and a photodiode on both sides of the gate insulating layer pattern and the gate electrode pattern by selectively doping impurity ions into the semiconductor substrate a plurality of times.