Patent ID: 7544530

Claim:
A method for manufacturing a CMOS image sensor, comprising the steps of: forming an isolation layer on a semiconductor substrate, the isolation layer defining an active region including a photo diode region and a transistor region; forming a gate in the transistor region, the gate including a gate insulating layer and a gate electrode thereon; forming a first low-concentration diffusion region in the photo diode region; forming a second low-concentration diffusion region in the transistor region; forming a buffer layer over the substrate, the buffer layer having an opening exposing the transistor region; forming first and second insulating layers over an entire surface of the substrate, including on the buffer layer in the photo diode region, the first and second insulating layers having a different etching selectivity from each other; forming an insulating sidewall on sides of the gate electrode by selective removal of the second insulating layer, including on the first insulating layer in the transistor region and the photo diode region, and on the buffer layer in the photo diode region; selectively removing the first insulating layer to expose the transistor region; forming a high-concentration diffusion region in the exposed transistor region, partially overlapping the second low-concentration diffusion region; and forming a metal silicide layer on a surface of the high-concentration diffusion region.