CMOS image sensor n-type pin-diode structure
First Claim
1. A method of forming an image sensor comprising:
- providing a partially processed semiconductor wafer containing p-type and/or n-type regions which are bounded by isolation regions and with gate oxide layers grown on the surfaces upon which gate electrode structures are disposed, some of said gate electrode structures will serve as gate electrodes of image sensor transistors;
forming source/drain regions about the said gate electrode structures;
the area to be photodiode regions being masked during said forming of source/drain regions;
forming two photodiode regions of the same conductivity type as said source/drain regions and overlapping one of the source drain regions;
one of the photodiode regions being shallow and of high carrier density and the other being deeper and of a lower carrier density;
said source/drain regions, except for the areas of overlap, being masked during said forming of two photodiode regions;
depositing a blanket transparent insulating layer;
providing electrical contact through the transparent insulating layer to the gate structures, the overlapped source/drain regions and the photodiode regions.
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Abstract
A method of forming an image sensor is disclosed. A partially processed semiconductor wafer is provide, containing p-type and/or n-type regions which are bounded by isolation regions and with gate oxide layers grown on the surfaces upon which gate electrode structures are disposed, some of said gate electrode structures will serve as gate electrodes of image sensor transistors. Ions are implanted to form source/drain structures about the said gate electrode structures. To form photodiodes ions are implanted in two steps overlapping a source/drain region. A deeper implant provides a low charge carrier density region and a shallow implant provides a high charge carrier density region near the surface. A blanket transparent insulating layer is deposited.
57 Citations
32 Claims
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1. A method of forming an image sensor comprising:
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providing a partially processed semiconductor wafer containing p-type and/or n-type regions which are bounded by isolation regions and with gate oxide layers grown on the surfaces upon which gate electrode structures are disposed, some of said gate electrode structures will serve as gate electrodes of image sensor transistors;
forming source/drain regions about the said gate electrode structures;
the area to be photodiode regions being masked during said forming of source/drain regions;
forming two photodiode regions of the same conductivity type as said source/drain regions and overlapping one of the source drain regions;
one of the photodiode regions being shallow and of high carrier density and the other being deeper and of a lower carrier density;
said source/drain regions, except for the areas of overlap, being masked during said forming of two photodiode regions;
depositing a blanket transparent insulating layer;
providing electrical contact through the transparent insulating layer to the gate structures, the overlapped source/drain regions and the photodiode regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of forming an image sensor comprising:
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providing a partially processed semiconductor wafer containing p-type and/or n-type regions which are bounded by isolation regions and with gate oxide layers grown on the surfaces;
forming a well of the opposite conductivity type of said semiconductor region to be deep, low carrier density photodiode region;
regions to be source/drain regions, except for the region of overlap, being masked during said forming of said well;
forming gate electrode structures some of which will serve as gate electrodes of image sensor transistors;
forming LDD source/drain regions about said gate electrode structures, with source/drain regions of image sensors being of the same conductivity type as said well, and one of the source/drain regions overlapping said well;
said well, except for region of overlap, being masked during said forming of LDD source/drain regions;
forming shallow, high density photodiode region overlapping said well and source/drain region;
said source/drain regions, except for region of overlap, being masked during said forming of high density photodiode region;
depositing a blanket transparent insulating layer;
providing electrical contact through said transparent insulating layer to the gate structures, the unoverlapped source/drain regions and the photodiode regions. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification