A CMOS image sensor includes a photosensitive device, a floating diffusion region, a transfer transistor, and a pocket photodiode formed in a semiconductor substrate of a first conductivity type. The floating diffusion region is of a second conductivity type. The transfer transistor has a channel region disposed between the photosensitive device and the floating diffusion region. The pocket photodiode is of the second conductivity type and is formed under a first portion of a bottom surface of the channel region such that a second portion of the bottom surface of the channel region abuts the semiconductor substrate.