Patent ID: 7927902

Claim:
A method of fabricating an image sensor, comprising: providing a substrate including a light-receiving region and a non-light-receiving region; forming a plurality of gates on the non-light-receiving region; ion-implanting a first-conductivity-type dopant into the light-receiving region to form a first dopant region of a pinned photodiode; primarily ion-implanting a second-conductivity-type dopant, different from the first-conductivity-type dopant, into an entire surface of the substrate, using the plurality of gates as a first mask; masking the light-receiving region a first time; ion-implanting the first-conductivity-type dopant and the second-conductivity-type dopant into the non-light-receiving region to form lower-concentration dopant regions of low doped drains aligned to the plurality of gates before forming spacers on both side walls of the plurality of gates; unmasking the light-receiving region the first time; forming the spacers on both side walls of the plurality of gates; and secondarily ion-implanting the second-conductivity-type dopant into the entire surface of the substrate, using the plurality of gates including the spacers as a second mask, to complete a second dopant region of the pinned photodiode; masking the light-receiving region a second time; ion-implanting the first-conductivity-type dopant and the second-conductivity-type dopant into the non-light-receiving region to form higher-concentration dopant regions of the low doped drains aligned to the spacers after forming the spacers on both side walls of the plurality of gates; and unmasking the light-receiving region the second time.