Method of reducing dark current for an image sensor device via use of a polysilicon pad
US6534356B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 2002 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Apr 9, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10F39/80
Abstract
A process for reducing the dark current generation of an image sensor cell, fabricated on a semiconductor substrate, has been developed. The process features the use of polysilicon pad structure, formed simultaneously with a polysilicon gate structure of a reset transistor, with the polysilicon pad structure located overlying, and contacting, a portion of the top surface of the photodiode element, of the image sensor cell. A small diameter opening, in a composite polysilicon-silicon oxide layer, exposes the portion of photodiode element to be contacted by the polysilicon pad structure. The small diameter opening is created using a procedure which allows the surface of the photodiode element, exposed in the small diameter opening to experience only a minimum of RIE processing at end point, thus minimizing damage to the surface of the photodiode element, and thus reducing dark current generation. A metal contact structure, used to communicate with the photodiode element, is then formed on the polysilicon pad structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.