Patent ID: 8013365

Claim:
A complementary metal-oxide-semiconductor (CMOS) image sensor (CIS), comprising: a semiconductor substrate including a photodiode therein as a light sensing unit; a floating diffusion region of a first conductivity type in the semiconductor substrate and configured to receive charges generated in the photodiode; a power supply voltage region of the first conductivity type in the semiconductor substrate; a reset transistor comprising a reset gate electrode on a surface of the substrate between the floating diffusion region and a power supply voltage region and configured to discharge charges stored in the floating diffusion region in response to a reset control signal, the reset transistor comprising a channel region in the substrate extending between the floating diffusion region and the power supply voltage region such that the floating diffusion region and the power supply voltage regions define source/drain regions for the reset transistor; and an impurity region in a first portion of the channel region adjacent to the floating diffusion region, the impurity region having a doping such that the first portion of the channel region adjacent to the floating diffusion region has a different built-in potential than a second portion of the channel region adjacent to the power supply voltage region, wherein the second portion of the channel region adjacent to the power supply voltage region has a higher voltage potential than the first portion of the channel region adjacent to the floating diffusion region, wherein the impurity region in the first portion of the channel region comprises a second conductivity type different from the first conductivity type, and wherein the second portion of the channel region comprises the first conductivity type.