US Patent 7498650 Backside illuminated CMOS image sensor with pinned photodiode

A backside illuminated CMOS image sensor having an silicon layer with a front side and a backside, the silicon layer liberates charge when illuminated from the backside with light, an active pixel circuitry located on the front side of the semiconductor layer, a pinned photodiode adjacent to the active pixel circuitry on the front side of the semiconductor layer and configured to collect charge liberated in the semiconductor layer, and an implant located in the semiconductor layer, underneath the active pixel circuitry, for allowing charge liberated in the semiconductor layer to drift from the backside of the semiconductor layer to the pinned photodiode on the front side of the semiconductor layer.