Fully isolated photodiode stack

US7608874B2 · kind B2 · utility

Assignee

• Sharp Laboratories of America, Inc. · US

Inventors

• Jong-Jan Lee · Camas, US
• Douglas J. Tweet · Camas, US
• Sheng Teng Hsu · Camas, US

Key dates

• Filing date: Jan 24, 2007
• Grant date: Oct 27, 2009
• Expiry date: Jan 9, 2028

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F39/807

Abstract

An array of fully isolated multi-junction complimentary metal-oxide-semiconductor (CMOS) filterless color imager cells is provided, together with an associated fabrication method. The method provides a bulk silicon (Si) substrate. A plurality of color imager cells are formed, either in the Si substrate, or in a single epitaxial Si layer formed over the substrate. Each color imager cell includes a photodiode set with a first, second, and third photodiode formed as a stacked multi-junction structure. A U-shaped (in cross-section) well liner, fully isolates the photodiode set from adjacent photodiode sets in the array. For example, each photodiode is formed from a p doped Si layer physically interfaced to a first wall. A well bottom physically interfaces to the first wall, and the p doped Si layer of the third, bottom-most, photodiode is part of the well bottom. Then, the photodiode sets may be formed from an n/p/n/p/n/p or n/p/p−/p/p−/p layered structure.