IMAGE SENSORS OPERABLE IN GLOBAL SHUTTER MODE AND HAVING SMALL PIXELS WITH HIGH WELL CAPACITY

摘要

An image sensor operable in global shutter mode ma include small pixels with high charge storage capacity, low dark current, and no image lag. Storage capacity of a photodiode and a charge storage diode may be increased by placing a p+ type doped layer under the photodiode and the charge storage diode. The p+ type doped layer ma include an opening for allowing photo-generated charge carriers to flow from the silicon bulk to the charge storage well located near the surface of the photodiode. A compensating n− type doped implant may be formed in the opening. Image lag is prevented by placing a p− type doped region under the p+ type doped photodiode pinning layer and aligned with the opening. The p+ type doped layer may extend under the entire pixel array.

主权项

1. An image sensor pixel in a pixel array having a silicon substrate, comprising:
a photodiode and a charge storage diode formed in a surface of the silicon substrate, wherein the silicon substrate includes a hulk portion under the photodiode and the charge storage diode; a p+ type doped layer that extends under the photodiode and the charge storage diode parallel to the surface, wherein the p+ type doped layer comprises an opening through which charge carriers pass from the bulk portion of the silicon substrate to the photodiode; and a compensating n− type doped implant region in the opening.