Integrated structure for reduced leakage and improved fill-factor in CMOS pixel

摘要

A densely integrated pixel, fabricated by CMOS technology, comprises a photodiode formed by a n-well, with cathode, surrounded by a p-well; a reset MOS transistor formed such that its polysilicon gate is positioned, for diode control, across the junction formed by p-well and n-well regions, and its source is merged with the photodiode cathode; and a sensing MOS transistor formed such that its source is combined with the drain of the reset transistor and its gate is electrically connected to the source of the reset transistor.In the pixel of the invention, the photodiode leakage current is greatly reduced, because no n+/p-well junction is connected to the photodiode, and the fill factor is improved, because the pixel size is much reduced.