Patent ID: 8642374

Claim:
A method of fabricating an image sensor comprising: forming a first gate oxide layer over a substrate; forming a second gate oxide layer over the substrate, wherein forming a first gate oxide layer comprises forming a thick gate oxide layer and wherein forming a second gate oxide layer comprises forming a thin gate oxide layer; forming a layer of photoresist over the first gate oxide layer; applying nitridation to the photoresist and the second gate oxide layer such that the first gate oxide layer is protected from the nitridation by the photoresist; removing the photoresist; forming a polysilicon gate over the first gate oxide layer; forming a polysilicon gate over the second gate oxide layer; forming a first transistor using the first gate oxide layer, wherein forming the first transistor includes forming an amplifier; forming a second transistor using the second gate oxide layer; and forming a reset transistor and a transmit transistor using the second gate oxide layer.