Image sensor having a charge storage region provided within an implant region
AssigneeAptina Imaging Corporation
InventorsHoward Rhodes, Chandra Mouli
Life of this patent
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Abstract
A deep implanted region of a first conductivity type located below a transistor array of a pixel sensor cell and adjacent a doped region of a second conductivity type of a photodiode of the pixel sensor cell is disclosed. The deep implanted region reduces surface leakage and dark current and increases the capacitance of the photodiode by acting as a reflective barrier to photo-generated charge in the doped region of the second conductivity type of the photodiode. The deep implanted region also provides improved charge transfer from the charge collection region of the photodiode to a floating diffusion region adjacent the gate of the transfer transistor.
Claims20
-112. (canceled)
A method of forming a photosensor of a pixel cell, said method comprising:
- forming a first doped layer of a first conductivity type in a substrate;
- forming a doped region of a second conductivity type in said first doped layer and between a gate structure and an isolation region;
- and
- forming an implanted region of said second conductivity type, having a second dopant concentration, within said substrate, wherein said implanted region is located laterally of said photosensor and adjacent said charge collection region, and wherein said implanted region extends vertically within said substrate to a second depth which is greater than said first depth;
- and
- forming a charge storage region of said first conductivity type in said implanted region for receiving charges gated by said gate structure, wherein said first dopant concentration and said second dopant concentration are unequal.
A method of forming an image sensor, said method comprising:
- forming a silicon substrate having a first dopant concentration;
- forming a shallow trench isolation region within said silicon substrate;
- forming a pixel within an area at least partially defined by said shallow trench isolation region, forming said pixel comprising the steps of:
- forming a photodiode;
- forming a channel region of a transistor adjacent said photodiode;
- forming an implanted region, having a second dopant concentration, within said silicon substrate and adjacent said photodiode and said channel region;
- and
- forming a charge storing floating diffusion region formed in said implanted region,
- wherein said first dopant concentration and said second dopant concentration are unequal.
Dependencies are inferred from the claim text.