US5608243A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single split-gate MOS transistor active pixel sensor cell with automatic anti-blooming and wide dynamic range
Assignee: Foveon Inc
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Filing: 1995-10-19
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Granted: 1997-03-04
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Expires: 2015-10-19
Abstract
Abstract The size of an active pixel sensor cell is reduced by utilizing a single split-gate MOS transistor and a reset gate. The split-gate transistor includes an image collection region which is formed in the drain region and electrically connected to the floating gate of the transistor. Light energy striking the image collection region varies the potential of the floating gate which, in turn, varies the threshold voltage of the transistor. As a result, the current sourced by the transistor is proportional to the received light energy.
Inventors
- 👤 Min-Hwa Chi
- 👤 Albert Bergemont
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:45
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/10; H10F39/12; H10F39/15; H10F39/158
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
218 words
An active pixel sensor cell formed in a semiconductor substrate of a first conductivity type, the cell comprising: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gate being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate.
Claim 2
Dependent Claim
218 words
An active pixel sensor cell formed in a semiconductor substrate of a first conductivity type, the cell comprising: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gate being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate.
Claim 3
Dependent Claim
20 words
The cell of claim 1 wherein the junction between the image collection region and the second region forms a photodiode.
Claim 4
Independent Claim
257 words
A method for resetting an active pixel sensor cell formed in substrate of a first conductivity type, the active pixel sensor cell including: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gate being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate, the method including the steps of: applying zero potential to the substrate and the second conductive gate; applying a first voltage to the second region; and applying a second voltage to the reset gate.
Claim 5
Independent Claim
257 words
A method for resetting an active pixel sensor cell formed in substrate of a first conductivity type, the active pixel sensor cell including: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gate being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate, the method including the steps of: applying zero potential to the substrate and the second conductive gate; applying a first voltage to the second region; and applying a second voltage to the reset gate.
Claim 6
Dependent Claim
11 words
The method of claim 3 wherein the first voltage is positive.
Claim 7
Dependent Claim
11 words
The method of claim 4 wherein the second voltage is negative.
Claim 8
Independent Claim
296 words
A method for reading an active pixel sensor cell formed in substrate of a first conductivity type, the active pixel sensor cell including: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gates being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate, the method including the steps of: exposing the sensor cell to photons for a predetermined period of time, the photons causing a voltage on the image collection region and the first conductive gate to change; and applying a voltage to the second conductive gate, wherein the voltage on the first conductive gate and the voltage on the second conductive gate cause a current to flow from the second region to the first region.
Claim 9
Independent Claim
296 words
A method for reading an active pixel sensor cell formed in substrate of a first conductivity type, the active pixel sensor cell including: a first region of a second conductivity type formed in the substrate; a second region of the second conductivity type formed in the substrate, the first and second regions defining a channel region therebetween, an image collection region of the first conductivity type formed in the second region, a first conductive gate electrically connected to the image collection region, the first conductive gates being formed over a first portion of the channel region and a portion of the second region and separated therefrom by a first layer of dielectric material, and a second conductive gate formed over a second portion of the channel region and a portion of the first conductive gate, the second conductive gate formed over a second portion of the channel region being separated therefrom by a second layer of dielectric material, the second conductive gate formed over the first conductive gate being separated therefrom by a third layer of dielectric material; and a reset gate formed over a portion of the second region that adjoins the image collection region and the substrate, the reset gate being separated from the second region by a fourth layer of dielectric material, and electrically isolated from the second conductive gate, the method including the steps of: exposing the sensor cell to photons for a predetermined period of time, the photons causing a voltage on the image collection region and the first conductive gate to change; and applying a voltage to the second conductive gate, wherein the voltage on the first conductive gate and the voltage on the second conductive gate cause a current to flow from the second region to the first region.
Claim 10
Dependent Claim
21 words
The method of claim 6 wherein a magnitude of the current is proportional to the voltage on the first conductive gate.
Claim 11
Dependent Claim
18 words
The method of claim 7 wherein the photons cause the voltage on the first conductive gate to rise.
Claim 12
Dependent Claim
16 words
The method of claim 8 wherein the voltage applied to the second conductive gate is positive.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-03-03 | 2000-09-02 | 2001-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-03 | 2004-09-02 | 2005-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-03-03 | 2008-09-02 | 2009-03-04 | $7700.00 | Window Closed / Lapsed |