Operation and performance of a color image sensor with layered photodiodes

Abstract

A silicon image sensor has been developed and placed in production using standard 0.18 μm CMOS process having three stacked photodiodes per pixel location to provide full-color imaging without external color filters. With a fill factor exceeding 50%, this image sensor achieves approximately 45% peak quantum efficiency in the mid range visible and provides usable response extending from the near-ultraviolet to the near-infrared. Initial results from a commercial digital still camera indicate that this device can produce excellent color reproduction with equivalent ISO film speeds from 100 to 400 and that it produces images free from color artifacts common in images made with sensors incorporating color filter arrays. Development is now underway on camera equipment designed to operate this image sensor in a variety of scan modes.