Pixel with asymmetric transfer gate channel doping

US7557397B2 · kind B2 · utility

Assignee

• Aptina Imaging Corporation · KY

Inventors

• Chintamani Palsule · Lake Oswego, US
• Changhoon Choi · Palo Alto, US
• Fredrick P. LaMaster · Fort Collins, US
• John Stanback · Fort Collins, US
• Thomas Dungan · Fort Collins, US
• Thomas Joy · Medford, US
• Homayoon Haddad · Beaverton, US

Key dates

• Filing date: Feb 16, 2007
• Grant date: Jul 7, 2009
• Expiry date: Aug 28, 2027

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F77/147

Abstract

A pixel including a substrate of a first conductivity type and having a surface, a photodetector of a second conductivity type that is opposite the first conductivity type, a floating diffusion region of the second conductivity type, a transfer region between the photodetector and the floating diffusion, a gate positioned above the transfer region and partially overlapping the photodetector, and a pinning layer of the first conductivity type extending at least across the photodetector from the gate. A channel implant of the first conductivity type extending from between a midpoint of the transfer gate and the floating diffusion to at least across the photodiode and having a dopant concentration such that a dopant concentration of the transfer region is greater proximate to the photodetector than the floating diffusion, and wherein a peak dopant concentration of the channel implant is at a level and at a depth below the surface such that a partially-buried channel is formed in the transfer region between the photodiode and floating diffusion when the transfer gate is energized.