Stacked pixels for high resolution CMOS image sensors with BCMD charge detectors

US8946845B1 · kind B1 · utility

Assignee

• Aptina Imaging Corporation · KY

Inventors

• Jaroslav Hynecek · Allen, US
• Hirofumi Komori · San Jose, US
• Xia Zhao · Highland Park, US

Key dates

• Filing date: Jun 3, 2011
• Grant date: Feb 3, 2015
• Expiry date: Nov 7, 2032

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F39/8037

Abstract

The invention describes in detail a solid-state CMOS image sensor, specifically a CMOS image sensor pixel that has stacked photo-sites, high sensitivity, and low dark current. The pixels have incorporated therein special potential barriers under the standard pinned photodiode region that diverts the photo-generated electrons from a deep region within the silicon bulk to separate storage structures located at the surface of the silicon substrate next to the pinned photodiode. The storage structures are p channel BCMD transistors that are biased to a low dark current generation mode during a charge integration period. The signal readout from the BCMD is nondestructive, therefore, without kTC noise generation. Thus a single pixel is capable of detecting several color-coded signals while using fewer or without using any light absorbing color filters on top of the pixel. The image sensors constructed with the stacked photo-sites with BCMD readout have higher pixel densities, higher resolution, higher sensitivity, very low dark current, and no color aliasing if at least three depth encoded signals are read from a single photodiode. The pixels having stacked photo-sites with BCMD readout …