Photodiode with self-aligned implants for high quantum efficiency and method of formation
AssigneeAptina Imaging Corporation
InventorsChandra Mouli, Howard Rhodes
Life of this patent
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Abstract
A pinned photodiode with a pinned surface layer formed by a self-aligned angled implant is disclosed. The angle of the implant may be tailored to provide an adequate offset between the pinned surface layer and an electrically active area of a transfer gate of the pixel sensor cell. The pinned surface layer is formed by employing the same mask level as the one employed for the formation of the photodiode region, and then implanting dopants at angles other than zero degrees.
Claims29
A photodiode for use in an imaging device, said photodiode comprising:
- a charge collection region formed in a substrate of a first conductivity type for accumulating photo-generated charge, said charge collection region being of a second conductivity type and being adjacent a gate of a transistor formed over said substrate, said gate transferring charge accumulated in said charge collection region to a doped region of said second conductivity type;
- and
- a doped layer of said first conductivity type, said doped layer being laterally displaced from an electrically active portion of said gate by a distance of about 200 to about 1,000 Angstroms.
An image pixel comprising:
- an isolation region formed within a semiconductor substrate;
- a gate structure of a transfer transistor formed over said semiconductor substrate;
- and
- a photodiode adjacent said gate, said photodiode comprising a surface layer of a first conductivity type and a doped region of a second conductivity type located below said surface layer and extending below at least a portion of said gate structure, said surface layer being laterally displaced from an electrically active portion of said gate by a distance of about 200 to about 1,000 Angstroms and in contact with said isolation region.
A CMOS image sensor comprising:
- a semiconductor substrate;
- an isolation region formed within said semiconductor substrate;
- and
- a pixel adjacent said isolation region, said pixel comprising a photodiode adjacent a gate of a transistor, said photodiode further comprising a surface layer of a first conductivity type and a doped region of a second conductivity type located below said surface layer and extending below at least a portion of said gate, said surface layer being laterally displaced from an electrically active portion of said gate by a distance of about 200 to about 1,000 Angstroms and in contact with said isolation region.
A CMOS image sensor comprising:
- a silicon substrate;
- a field oxide region formed within said silicon substrate;
- and
- a pixel adjacent said field oxide region, said pixel comprising a p-n-p photodiode adjacent a gate of a transistor, said p-n-p photodiode further comprising a p-type surface layer and an n-type doped region located below said p-type surface layer and relative to said p-type surface layer, said p-type surface layer being laterally displaced from said gate by a distance of about 200 to about 1,000 Angstroms and in contact with said field oxide region.
Dependencies are inferred from the claim text.