Low lag transfer gate device
First Claim
1. An active pixel sensor (APS) cell structure comprising:
- a substrate of a first conductivity type material;
a gate dielectric layer formed on the substrate;
a gate conductor structure formed on the gate dielectric layer, said gate conductor structure comprising a first doped region of first conductivity type material including an associated first transfer gate electrode and a second doped region of a second conductivity type material including an associated second transfer gate electrode, wherein the first doped region is in direct contact with the second doped region;
a photosensing device formed at or below a substrate surface adjacent said first doped region of said gate conductor structure for collecting charge carriers in response to light incident thereto;
a diffusion region of a second conductivity type material formed at or below said substrate surface adjacent said second doped region of said gate conductor structure , said gate conductor structure defining a channel region in said substrate enabling charge transfer between said photosensing device and said diffusion region, andcircuit device including separate conductors entirely physically and electrically isolated from one another to each of said first and second transfer gate electrodes to apply separate voltage signals to each said first and second transfer gate electrodes by direct electrical contact to each of the first and second doped regions, said voltage signals timed for transferring collected charge carriers from said photosensing device to said diffusion region while preventing spillback of charges to said photosensing device.
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Accused Products
Abstract
A CMOS active pixel sensor (APS) cell structure includes at least one transfer gate device and method of operation. A first transfer gate device comprises a diodic or split transfer gate conductor structure having a first doped region of first conductivity type material and a second doped region of a second conductivity type material. A photosensing device is formed adjacent the first doped region for collecting charge carriers in response to light incident thereto, and, a diffusion region of a second conductivity type material is formed at or below the substrate surface adjacent the second doped region of the transfer gate device for receiving charges transferred from the photosensing device while preventing spillback of charges to the photosensing device upon timed voltage bias to the diodic or split transfer gate conductor structure.
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Citations
13 Claims
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1. An active pixel sensor (APS) cell structure comprising:
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a substrate of a first conductivity type material; a gate dielectric layer formed on the substrate; a gate conductor structure formed on the gate dielectric layer, said gate conductor structure comprising a first doped region of first conductivity type material including an associated first transfer gate electrode and a second doped region of a second conductivity type material including an associated second transfer gate electrode, wherein the first doped region is in direct contact with the second doped region; a photosensing device formed at or below a substrate surface adjacent said first doped region of said gate conductor structure for collecting charge carriers in response to light incident thereto; a diffusion region of a second conductivity type material formed at or below said substrate surface adjacent said second doped region of said gate conductor structure , said gate conductor structure defining a channel region in said substrate enabling charge transfer between said photosensing device and said diffusion region, and circuit device including separate conductors entirely physically and electrically isolated from one another to each of said first and second transfer gate electrodes to apply separate voltage signals to each said first and second transfer gate electrodes by direct electrical contact to each of the first and second doped regions, said voltage signals timed for transferring collected charge carriers from said photosensing device to said diffusion region while preventing spillback of charges to said photosensing device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An active pixel sensor (APS) cell structure comprising:
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a substrate of a first conductivity type material; a gate dielectric layer formed on the substrate; a gate conductor structure formed on the gate dielectric layer, said gate conductor structure comprising a first doped region of first conductivity type material including an associated first transfer gate electrode and a second doped region of a second conductivity type material including an associated second transfer gate electrode, wherein the first doped region is in direct contact with the second doped region; a photosensing device formed at or below a substrate surface adjacent said first doped region of said gate conductor structure for collecting charge carriers in response to light incident thereto, the photosensing device comprising a photodiode comprising a collection well of a second conductivity type material formed below said substrate surface, and a pinning layer of said first conductivity type material formed atop the collection well at said substrate surface, wherein an innermost end of the pinning layer relative to a center of the gate conductor structure, and an innermost end of the collection well relative to a center of the gate conductor structure is substantially aligned to a first sidewall of the gate conductor structure and is horizontally offset from an interface between the first doped region and the second doped region of the gate conductor structure; a diffusion region of a second conductivity type material formed at or below said substrate surface adjacent said second doped region of said gate conductor structure, wherein an end of the diffusion region is substantially aligned to a second sidewall of the gate conductor structure and is horizontally offset from the interface between the first doped region and the second doped region of the gate conductor structure, said gate conductor structure defining a channel region in said substrate enabling charge transfer between said photosensing device and said diffusion region, and a circuit device including a first conductor to a first transfer gate electrode and a second conductor to a second transfer gate electrode to deliver separate voltage signals to each said first and second transfer gate electrodes by direct electrical contact to each of the first and second doped regions, wherein the first conductor is electrically isolated and physically separated from the second conductor, said voltage signals timed for transferring collected charge carriers from said photosensing device to said diffusion region while preventing spillback of charges to said photosensing device. - View Dependent Claims (11, 12, 13)
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Specification