Patent ID: 7556990

Claim:
A method for manufacturing a CMOS image sensor comprising the steps of: forming a pad oxide on a substrate having a first conductive type and including an image area and a circuit area; forming a nitride on the pad oxide; selectively etching the nitride and pad oxide sequentially so that a portion of the substrate where a field oxide is to be formed is exposed; forming a thermal oxide as a LOCOS field oxide in the substrate for electrical isolation within the image area, on the exposed portion of the substrate by performing a thermal oxidation process on the entire substrate; implanting channel stop ions below the formed thermal oxide; and forming a gate electrode on the circuit area of the substrate, wherein the gate electrode formation comprises the steps of: forming a CVD oxide layer on the entire surface of the substrate, including the thermal oxide, by performing CVD process; forming a polysilicon layer on the CVD oxide layer; and selectively etching the polysilicon layer and CVD oxide layer sequentially in such a way that both sides of the remaining CVD oxide layer overlap with the thermal oxide.