Pixel cell isolation of charge storage and floating diffusion regions using doped wells
AssigneeAptina Imaging Corporation
InventorParker Altice
Life of this patent
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Abstract
A pixel having a well-isolated charge storage region or floating diffusion region may be obtained by providing a separate P-well around the storage region or floating diffusion region. In one embodiment, a separate P-well entirely encases the storage region and is in contact with the storage region. This P-well provides an electrical barrier for preventing electrons that are generated elsewhere in the pixel from contaminating the storage region. In another embodiment, a first separate P-well encases and is in contact with the storage region and a second separate P-well encases and is in contact with the floating diffusion region.
Claims13
A pixel cell comprising:
- a first well region of a first conductivity type in a substrate;
- a photosensor within said substrate for generating photoelectrons;
- a storage region entirely within a second well region of greater doping concentration than said first well region and of said first conductivity type for storing photoelectrons generated by said photosensor;
- and
- a floating diffusion region within said first well region of said first conductivity type for receiving photoelectrons from said storage region.
A pixel array comprising:
- a plurality of pixels, at least one of said plurality of pixels comprising:
- a photosensor within a substrate for generating photoelectrons;
- a storage gate transistor;
- a storage region within a first P-well region for storing, upon activation of said storage gate transistor, photoelectrons generated by said photosensor;
- a transfer gate transistor;
- and
- a floating diffusion region in a second P-well region for receiving, upon activation of said transfer gate transistor, photoelectrons stored in said storage region.
Dependencies are inferred from the claim text.