Patent ID: 7517714
Filing Date: 2009-04-14
Classification: H01L

Abstract:
1. A method of fabricating an image sensor, said method comprising: implanting impurities of a first conductivity type in a semiconductor substrate to define a first channel region extending to a first depth from a surface of the semiconductor substrate; implanting impurities of a second conductivity type in the substrate surface to define a second channel region which is located over the first channel region and extends to a second depth from the substrate surface, wherein the first depth is greater than the second depth; forming a gate electrode over surface of the semiconductor substrate and over the first and second channel regions; implanting impurities of the first conductivity type in the semiconductor substrate to define a hole accumulated device (HAD) region which extends to a third depth from the substrate surface and which is adjacent the gate electrode; implanting impurities of the second conductivity type in the semiconductor substrate to define a photodiode which is buried in the substrate and extends to a fourth depth from substrate surface, wherein the fourth depth is greater than the third depth; implanting impurities of the second conductivity type in the semiconductor substrate to define a surface diffusion region which is over the HAD region and which is electrically connected to the second channel region; and, implanting impurities of the second conductivity type in the substrate to define a floating diffusion region which electrically contacts the second channel region; wherein the HAD region is located over the photodiode, and wherein an impurity concentration of the floating diffusion region is greater than an impurity concentration of the surface diffusion region and greater than an impurity concentration of the second channel region.