Patent ID: 9748299
Date: 2017-08-29
CPC Classifications: H01L

Claim:
1. A pixel for a backside illuminated (BSI) image sensor, the pixel comprising: a photoelectric conversion region interposed between a first surface and a second surface of a semiconductor substrate to generate charges in response to light received through the second surface; first trench isolation surrounding the photoelectric conversion region and extending vertically from the second surface; a floating diffusion region in the semiconductor substrate and occupying a level in the device below that occupied by the photoelectric conversion region; and a transfer gate extending vertically from the first surface in a direction towards the photoelectric conversion region to transfer the charges from the photoelectric conversion region to the floating diffusion region; a metal wiring region comprising a dielectric layer disposed on the first surface of the semiconductor substrate and metal wiring running through the dielectric layer; a second gate disposed in the metal wiring region adjacent to the first surface of the semiconductor substrate as spaced from the transfer gate; and an isolation region of insulation material in the semiconductor substrate, wherein the first trench isolation comprises negative charge material, the isolation region has a bottom surface coplanar with the first surface of the semiconductor substrate, and the bottom surface of the isolation region faces and overlaps the transfer gate and the second gate along the first surface of the semiconductor substrate, and the metal wiring is electrically connected to each of the transfer gate and the second gate.