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US 12,621,581 B2Granted
Reset gate for photodiode
AssigneeSemiconductor Components Industries, LLC
InventorDavid James Collins
Life of this patent
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Abstract
A buried channel that partially covers a reset gate channel of a pixel for a light sensor is disclosed. The buried channel can lower a potential barrier between a photodiode and the reset gate so that charge can be drained from the photodiode region faster during a reset period. This may result in a shorter reset period that can increase the frame rate of a global shutter.
Claims20
A light-sensing pixel, comprising:
- a first channel layer adjacent to a photodiode region, adjacent to a reset-node region, and extending a first channel length to fill a space between the photodiode region and the reset-node region;
- a reset gate adjacent to a top surface of the first channel layer and extending the first channel length so that a reset-gate voltage applied to the reset gate generates a first conductive channel between the photodiode region and the reset-node region;
- a photodiode-extension layer adjacent to a bottom surface of the first channel layer opposite the top surface, the photodiode-extension layer extending from the photodiode region by an extension length that is less than the first channel length;
- a second channel layer extending between the photodiode region and a storage-node region;
- and
- an anti-blooming layer adjacent to the second channel layer.
3 more elements
A light-sensing pixel comprising:
- a photodiode configured to generate charge based on received light;
- a reset transistor coupled between the photodiode and a reset-node, the reset transistor including:
- a reset gate;
- a first channel layer adjacent to the reset gate at a top surface, the first channel layer configured to generate a first conductive channel between the photodiode and the reset-node while a reset-gate voltage is applied to the reset gate;
- and
- a buried channel at a bottom surface of the first channel layer opposite the top surface, the buried channel having an extension length that is less than a channel length of the first channel layer in a direction aligned with the first conductive channel;
- and
- a transfer transistor coupled between the photodiode and a storage-node, the transfer transistor including:
- a transfer gate;
- a second channel layer extending between a photodiode region and a storage-node region;
- and
- an anti-blooming channel adjacent to the second channel layer.
9 more elements
A method for resetting a light-sensing pixel, the method comprising:
- generating a first charge in a photodiode region of the light-sensing pixel;
- applying a reset voltage to a reset-node region of the light-sensing pixel, the reset-node region separated from the photodiode region by a first channel layer, the light-sensing pixel including a photo-diode extension layer partially covering a bottom surface of the first channel layer;
- applying a reset-gate voltage to a reset gate adjacent to the first channel layer;
- generating a conductive channel between the photodiode region and the reset-node region in response to the reset-gate voltage;
- draining the first charge from the photodiode region through the conductive channel to reset the light-sensing pixel;
- accumulating a second charge in the photodiode region of the light-sensing pixel during an exposure period;
- and
- applying a voltage to a transfer gate on a top surface of a second channel layer to couple the second charge to a storage node, the transfer gate extending a second channel length between the photodiode region and a storage-node region, and the transfer gate including an anti-blooming layer adjacent to a bottom surface of the second channel layer and extending the second channel length.
5 more elements
Dependencies are inferred from the claim text.