Pixel with raised photodiode structure

摘要

An active pixel cell includes an isolation feature and a photodiode, in which the active pixel cell is on a semiconductor substrate with a top surface. The isolation feature is in the top surface of the semiconductor substrate. The photodiode is adjacent to the isolation feature. The photodiode includes a first-type pinned photodiode (PPD) and a second-type PPD. The first-type PPD is in the pixel region, in which the first-type PPD has a first-type PPD surface coplanar with the top surface. The second-type PPD is on the first-type PPD surface, in which the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface.

主权项

1. An active pixel cell on a semiconductor substrate with a top surface, the active pixel cell comprising:
an isolation feature in the top surface of the semiconductor substrate; and a photodiode adjacent to the isolation feature, wherein the photodiode comprises:
a first-type pinned photodiode (PPD) in the semiconductor substrate, wherein the first-type PPD has a first-type PPD surface coplanar with the top surface;a second-type PPD on the first-type PPD surface, wherein the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface, and the first-type PPD is one of an n-type PPD and a p-type PPD, and the second-type PPD is the other one of the n-type PPD and the p-type PPD; anda protective oxide which is disposed on and covers the second-type PPD and contacts a portion of a top surface of the second-type PPD.