| 摘要 |
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.
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