Patent ID: 8487350

Claim:
A complementary metal-oxide semiconductor (“CMOS”) image sensor, comprising: an epitaxial layer in or on which a pixel array is disposed, wherein a pixel cell of the pixel array includes: a photodiode disposed within the epitaxial layer to accumulate photo-generated charge; a floating node disposed within the epitaxial layer; and an entrenched transfer gate disposed within the epitaxial layer between the photodiode and the floating diffusion to control transfer of the photo-generated charge from the photosensitive region to the floating node, wherein the entrenched transfer gate comprises: a bottom portion disposed within a trench that extends into the epitaxial layer, the bottom portion having a trapezoidal shape with a long side facing the photodiode and a short side facing the floating node; and a top portion having a rectangular shape disposed over the bottom portion that extends above a top surface of the epitaxial layer.