Patent ID: 6974715

Claim:
A method for fabricating a complimentary metal-oxide-silicon (CMOS) image sensor including a low voltage buried photodiode and a transfer transistor, the method comprising: a) forming a field oxide for defining an active area and a field area on a certain area of an epitaxial layer formed on a substrate, and forming a gate of a transfer transistor on the epitaxial layer of the active area; b) forming a low voltage buried photodiode doping region in alignment with one side of the gate of the transfer transistor; c) forming a spacer insulation layer by stacking layers of oxide and nitride on the entire resulting structure of part (b); d) forming a spacer block mask on the spacer insulation layer to open area opposite the transfer transistor from the low voltage buried photodiode doping region while leaving the photodiode doping region covered by the spacer insulation layer and spacer block mask; and e) removing the spacer insulation layer not covered by the spacer block mask to form a spacer on a sidewall of the transistor, and removing the spacer block mask.