US Patent 7999342 Image sensor element for backside-illuminated sensor

Provided is a backside-illuminated sensor including a semiconductor substrate having a front surface and a back surface. A plurality of image sensor elements are formed on the front surface of the semiconductor substrate. At least one of the image sensor elements includes a transfer transistor and a photodetector. The gate of the transfer transistor includes an optically reflective layer. The gate of the transfer transistor, including the optically reflective layer, overlies the photodetector. In one embodiment, the gate overlies the photodetector by at least 5%.