Pixel with raised photodiode structure
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorYueh-Chuan Lee
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Abstract
An active pixel cell includes an isolation feature and a photodiode, in which the active pixel cell is on a semiconductor substrate with a top surface. The isolation feature is in the top surface of the semiconductor substrate. The photodiode is adjacent to the isolation feature. The photodiode includes a first-type pinned photodiode (PPD) and a second-type PPD. The first-type PPD is in the pixel region, in which the first-type PPD has a first-type PPD surface coplanar with the top surface. The second-type PPD is on the first-type PPD surface, in which the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface.
Claims17
An active pixel cell on a semiconductor substrate with a top surface, the active pixel cell comprising:
- an isolation feature in the top surface of the semiconductor substrate;
- and
- a photodiode adjacent to the isolation feature, wherein the photodiode comprises:
- a first-type pinned photodiode (PPD) in the semiconductor substrate, wherein the first-type PPD has a first-type PPD surface coplanar with the top surface;
- a second-type PPD on the first-type PPD surface, wherein the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface, and the first-type PPD is one of an n-type PPD and a p-type PPD, and the second-type PPD is the other one of the n-type PPD and the p-type PPD;
- and
- a protective oxide which is disposed on and covers the second-type PPD and contacts a portion of a top surface of the second-type PPD.
A method for fabricating an active pixel cell on a semiconductor substrate with a top surface, the method comprising:
- providing an isolation feature in the top surface of the semiconductor substrate;
- forming a photodiode adjacent to the isolation feature, wherein the forming comprises:
- forming a first-type pinned photodiode (PPD) in the semiconductor substrate, wherein the first-type PPD has a first-type PPD surface coplanar with the top surface;
- forming a second-type PPD on the first-type PPD surface, wherein the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface, and the first-type PPD is one of an n-type PPD and a p-type PPD, and the second-type PPD is the other one of the n-type PPD and the p-type PPD;
- and
- forming a protective oxide on and to cover the second-type PPD and contacts a portion of a top surface of the second-type PPD.
A method for fabricating an image sensor device, the method comprising:
- providing a semiconductor substrate with a top surface;
- forming an isolation feature disposed in the top surface to define a pixel region and a periphery region of the semiconductor substrate;
- forming a transistor gate and a gate structure respectively on the pixel region and the periphery region;
- doping first-type ions into the pixel region and the periphery region to form a first-type PPD and a first-type drain region in the pixel region, and to form a first-type source/drain region in the periphery region, wherein the transistor gate is between the first-type PPD and the first-type drain region, and the gate structure is between the first-type source/drain region, wherein the first-type PPD has a first-type PPD surface coplanar with the top surface;
- forming a second-type PPD on the first-type PPD surface, wherein the second-type PPD has a second-type PPD surface which is elevated higher than the first-type PPD surface, and the first-type PPD is one of an n-type PPD and a p-type PPD, and the second-type PPD is the other one of the n-type PPD and the p-type PPD;
- and
- forming a protective oxide on and to cover the second-type PPD and contact a portion of a top surface of the second-type PPD.
Dependencies are inferred from the claim text.