Patent ID: 7537971

Claim:
A method for fabricating a complementary metal-oxide semiconductor (CMOS) image sensor, comprising: performing an ion implantation process onto a photodiode region in a first conductivity type semiconductor layer to form a second conductivity type first impurity region; and performing an annealing process in a gas atmosphere including first conductivity type impurity atoms to form a first conductivity type second impurity region underneath a surface of the first conductivity type semiconductor layer in the second conductivity type first impurity region, wherein the first conductivity type second impurity region is doped with the diffused first conductivity impurity atoms, wherein the performing of the annealing process in the gas atmosphere including the first conductivity type impurity atoms to form the first conductivity type second impurity region comprises: forming a barrier layer over the substrate structure obtained before the annealing process; selectively wet etching the barrier layer to expose the surface of the first conductivity type semiconductor layer above the second conductivity type first impurity region; and performing the annealing process in the gas atmosphere including the first conductivity type impurity atoms onto the surface of the first conductivity type semiconductor layer exposed by the barrier layer to form the first conductivity type second impurity region.