Active pixel sensor integrated with a pinned photodiode
First Claim
Patent Images
1. A method of forming an active pixel sensor comprising the steps of:
- providing CMOS control circuitry operatively coupled through a transfer gate formed on a surface of the sensor to a pinned photodiode formed at the surface.
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Abstract
The optimization of two technologies (CMOS and CCD) wherein a pinned photodiode is integrated into the image sensing element of an active pixel sensor. Pinned photodiodes are fabricated with CCD process steps into the active pixel architecture. Charge integrated within the active pixel pinned photodiode is transferred into the charge sensing node by a transfer gate. The floating diffusion is coupled CMOS circuitry that can provide the addressing capabilities of individual pixels. Alternatively, a buried channel photocapacitor can be used in place of the pinned photodiode.
142 Citations
14 Claims
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1. A method of forming an active pixel sensor comprising the steps of:
providing CMOS control circuitry operatively coupled through a transfer gate formed on a surface of the sensor to a pinned photodiode formed at the surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 14)
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9. A method for integrating a pinned photodiode into an active pixel sensor comprising the steps of:
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providing a semiconductor material of a first conductivity type with a series of masking layers including at least one conductive layer on a major surface of the substrate; forming at least one well of a second conductivity type that is opposite the first conductivity type in an area where control circuitry is to be built, and forming an active area over the substrate; patterning at least one transfer gate along the surface of the substrate and a series of local interconnections; forming structures for a charge sensing means, including, creating patterns representing a first set of sources and drains for a predetermined set of transistors, including at least one drain for each of the transfer gates; introducing a second conductivity type opposite the first conductivity type so as to create the first set of sources and drains; patterning at least one image sensing area adjacent to the transfer gate; introducing within at least the image sensing area a material of the second conductivity type to create a photodiode; introducing at least on top of the photodiode a pinning layer comprising the first conductivity type; creating patterns representing a second set of sources and drains for a predetermined set of transistors; introducing the first conductivity type to create the second set of sources and drains; and creating a predetermined set of contacts on first and second sets of sources and drains. - View Dependent Claims (10, 11, 12, 13)
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Specification