US 2017/0013215 A1 · METHODS FOR CLOCKING AN IMAGE SENSOR

Abstract

A method of clocking an image sensor which eliminates well bounce effects caused by global current flow in large image sensors during frame readout and line transfer is described. During charge transfer operations in which voltages are applied to VCCD gate contacts that are adjacent to the photodiodes, a compensating voltage may be applied to the lightshield that is associated with, and at least partially formed over the photodiode. Depending on polarity, the compensating lightshield pulse allows holes to locally flow from under the VCCD gates to the photodiode P+ pinning region or vice-versa, and in such a manner to eliminate the global flow of hole current. Lightshields may also be biased during electronic shuttering operations.

Claims22

Dependent claims

A method of clocking an image sensor that includes a photodiode that is adjacent to a vertical charge-coupled device (VCCD), wherein the photodiode has an associated light-shielding structure that is formed over at least a part of the photodiode and the VCCD, the method comprising:

transferring charge in the photodiode to the VCCD;
and
while transferring the charge from the photodiode to the VCCD, applying a compensating bias voltage to the light-shielding structure to compensate for net charge imbalance caused by transferring the charge.

A method for clocking an image sensor that includes first and second photodiodes that are adjacent to a vertical charge-coupled device (VCCD), wherein the first photodiode is associated with a first light-shielding structure that is formed over at least a part of the first photodiode and the VCCD, and wherein the second photodiode is associated with a second light-shielding structure that is formed over at least a part of the second photodiode and the VCCD, the method comprising:

transferring a first charge in the first photodiode to the VCCD and transferring a second charge in the second photodiode to the VCCD, wherein the first photodiode is associated with a first plurality of gate contacts formed over the VCCD, and wherein the second photodiode is associated with a second plurality of gate contacts formed over the VCCD;
transferring the first charge from a first region in the VCCD under the first plurality of gate contacts to a second region in the VCCD under the second plurality of gate contacts;
and
while transferring the first charge, applying a compensating voltage to the light-shielding structures associated with the first and second photodiodes to compensate for net charge imbalance caused by transferring the first charge.

1 more element

Dependencies are inferred from the claim text.

Methods for clocking an image sensor

Life of this patent

Methods for clocking an image sensor

Life of this patent

Abstract

Claims22