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US 6,649,950 B2Granted
Active pixel having reduced dark current in a CMOS image sensor
AssigneeOmniVision Technologies, Inc.
InventorsXinping He, Chih-huei Wu, Tiemin Zhao
Life of this patent
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Abstract
The active pixel includes a photodiode, a transfer gate, and a reset transistor. The photodiode is substantially covered with an overlying structure, thus protecting the entire surface of the photodiode from damage. This substantially eliminates potential leakage current sources, which result in dark current. In one embodiment, the photodiode is covered by a FOX region in combination with the transfer gate.
Claims16
An active pixel formed in a semiconductor substrate comprising:
- an isolation region formed on said substrate defining an active area;
- a photodiode formed in said semiconductor substrate;
- an output node formed in said semiconductor substrate;
- and
- a transfer gate formed between said output node and said photodiode, such that substantially the entire surface of the photodiode is covered by either the transfer gate or said isolation region.
2 more elements
A CMOS image sensor comprising:
- a plurality of active pixels arranged in rows and columns, at least one of said active pixels comprising:
- (a) an isolation region formed in a substrate defining an active area;
- (b) a light sensitive element formed in said semiconductor substrate;
- (c) an output node formed adjacent to said light sensitive element;
- and
- (d) a transfer gate formed between said output node and said photodiode, such that substantially the entire surface of the light sensitive element is covered by either the transfer gate or the isolation region;
- a processing circuit for receiving the output of said active pixels;
- and
- an I/O circuit for outputting the output of said active pixels off of said CMOS image sensor.
6 more elements
Dependencies are inferred from the claim text.