Patent ID: 7935918

Claim:
An image sensor comprising: a photodiode comprising an n-doped region and a surface p-doped region; a floating diffusion node composed of an n+-doped region; and a transfer transistor including: a gate electrode a gate oxide layer beneath the gate; a channel underneath the gate oxide layer such that the gate oxide layer is interposed between the gate electrode and the channel, the channel comprising a portion of a p-substrate; a p-type doping portion in which holes are accumulated formed contiguous to and beneath the gate oxide layer of the transfer transistor and adjacent to the surface p-doped region of the photodiode so as to be between the surface p-type region and the channel, wherein the p-doped region of the photodiode is between the gate oxide layer and the n-doped region of the photodiode, and wherein the transfer transistor for transferring photon-induced charges created by the photodiode to the floating diffusion node, wherein the floating diffusion node and a channel of the transfer transistor are separated by a depletion region when the transfer transistor is turned on, so that the transfer transistor operates in a pseudo pinch-off mode.