ANTIBLOOMING IMAGING APPARATUS, SYSTEMS, AND METHODS

• US 20100219342A1
• Filed: 03/08/2010
• Published: 09/02/2010
• Est. Priority Date: 11/28/2006
• Status: Active Grant

• Current Assignee: Chen Xu, Gennadiy Agranov, Igor Karasev
• Original Assignee: Chen Xu, Gennadiy Agranov, Igor Karasev
• Inventors: Xu, Chen, Karasev, Igor, Agranov, Gennadiy
• Granted Patent: US 8,114,718 B2
• Time in Patent Office: Days
• US Class Current: 250/338.400
• CPC Class Codes: H04N 25/623 by evacuation via the output or reset lines
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

Apparatus, systems, and methods are described to assist in reducing dark current in an active pixel sensor. In various embodiments, a potential barrier arrangement is configured to block the flow of charge carriers generated outside a photosensitive region. In various embodiments, a potential well-potential barrier arrangement is formed to direct charge carriers away from the photosensitive region during an integration time.

Claims

1. A method comprising:

converting photons to electrons in a first potential energy region at a predetermined rate;

storing the electrons in the first potential energy region during an integration time; and

adjusting a first barrier energy relative to at least one of a second barrier energy or a third barrier energy to reduce the transfer of electrons from the second potential energy region to the first potential energy region during the integration time.

2. The method of claim 1, wherein converting photons to electrons includes converting photons having an energy range associated with a predetermined frequency band.

3. The method of claim 1, wherein converting photons to electrons includes converting photons associated with at least one of automobile light, sunlight, starlight, moonlight, or thermal energy.

4. The method of claim 1, wherein the converting photons to electrons includes selectively converting photons using at least one of a filter, a semiconductor band gap, or a reflective surface coating.

5. The method of claim 1, wherein storing includes accumulating electrons during the integration time using at least one of a lens or a shutter.

6. The method of claim 1, wherein storing includes accumulating electrons using a dopant atom adjusted barrier potential.

7. The method of claim 1, wherein storing includes accumulating electrons generated from photons associated with at least one of a visible wavelength, an ultraviolet wavelength, or an infrared wavelength.

8. The method of claim 1, wherein adjusting a first barrier energy relative to at least one of a second barrier energy and a third barrier energy includes applying one of a first voltage, a second voltage, or a third voltage.

9. The method of claim 1, wherein adjusting a first barrier energy relative to at least one of a second barrier energy or a third barrier energy includes using a dopant atom profile.

10. A method comprising:

converting photons to electrons in a first potential energy region in a photosensitive region at a predetermined rate;

storing the electrons in the first potential energy region during an integration time prior to transferring the electrons to a diffusion region for an associated read-out operation; and

adjusting a barrier energy between the diffusion region and a reset gate region directly adjacent the diffusion region to reduce the transfer of electrons from a second potential energy region to the first potential energy region during the integration time, the second potential energy region corresponding to the diffusion region.

11. The method of claim 10, wherein the method includes applying a potential, during the integration time, to a drain associated with the reset gate region, the drain providing a charge carrier sink.

12. The method of claim 10, wherein the method includes using a photosensitive region in which the first potential energy region includes a potential well with two ends, one end being adjacent a transfer gate region coupled to the diffusion region, the one end being adjacent a transfer gate region having a higher potential barrier height than the other based on a doping profile in the transfer gate region.

13. The method of claim 10, wherein the method includes using a reset gate region having in-band electronic states to form a conduction path between the diffusion region and a drain potential well.

14. The method of claim 10, wherein the photosensitive region includes a photodiode structure.

15. The method of claim 10, wherein the photosensitive region is located below a photogate.

16. A method comprising:

converting photons to electrons in a first potential energy region in a photosensitive region at a predetermined rate;

storing the electrons in the first potential energy region during an integration time prior to transferring the electrons to a diffusion region for an associated read-out operation; and

adjusting a barrier energy between the photosensitive region and a transfer gate region directly adjacent the photosensitive region relative to one or more barrier energies associated with a reset gate region directly adjacent the diffusion region, the adjustment to reduce the transfer of electrons from a second potential energy region to the first potential energy region during the integration time, the second potential energy region corresponding to the diffusion region.

17. The method of claim 16, wherein the method includes applying, during the integration time, a voltage to a gate above and corresponding to the reset gate region to permit charge carriers in the diffusion region to flow to a charge carrier sink away from the photosensitive region.

18. The method of claim 16, wherein the method includes using a transfer gate region and a reset gate region each having a doping profile selected to enhance electron flow from the diffusion region to a drain adjacent to and corresponding to reset gate region while reducing the transfer of electrons to the photosensitive region during the integration time.

19. The method of claim 16, wherein the method include receiving light at the photosensitive region from backside illumination of a substrate in which the photosensitive region is disposed in the substrate opposite the backside.

20. The method of claim 19, wherein receiving light at the photosensitive region from backside illumination of a substrate includes receiving the light resulting from optical filtering at the backside.