CMOS PHOTOGATE 3D CAMERA SYSTEM HAVING IMPROVED CHARGE SENSING CELL AND PIXEL GEOMETRY

• US 20100039546A1
• Filed: 07/17/2009
• Published: 02/18/2010
• Est. Priority Date: 07/17/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft International Holdings BV (Microsoft Corporation)
• Inventors: SHACHAM, Amit, COHEN, David
• Granted Patent: US 8,264,581 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes

Abstract

A photosurface for receiving and registering light from a scene, the photosurface comprising: a first semiconductor region in which electron-hole pairs are generated responsive to light incident on the photosurface; a single, first conductive region substantially overlaying all of the first semiconductor region; at least one second semiconductor region surrounded by the first semiconductor region; a different second conductive region for each second semiconductor region that surrounds the second semiconductor region and is electrically isolated from the first conductive region; wherein when the second conductive region is electrified positive with respect to the first conductive region, electrons generated by light incident on the first semiconductor region are collected in the second semiconductor region.

Claims

1. A photosurface for receiving and registering light from a scene, the photosurface comprising:

a first semiconductor region in which electron-hole pairs are generated responsive to light incident on the photosurface;

a single, first conductive region substantially overlaying all of the first semiconductor region;

at least one second semiconductor region surrounded by the first semiconductor region;

a different second conductive region for each second semiconductor region that surrounds the second semiconductor region and is electrically isolated from the first conductive region;

wherein when the second conductive region is electrified positive with respect to the first conductive region, electrons generated by light incident on the first semiconductor region are collected in the second semiconductor region.

2. A photosurface according to claim 1 wherein collected electrons migrate to the second semiconductor region from substantially all azimuthal directions relative to the second semiconductor region.

3. A photosurface according to claim 1 wherein the at least one second region comprises a plurality of second regions.

4. A photosurface according to claim 3 wherein the second regions have a characteristic radial extent of about 0.6 microns.

5. A photosurface according to claim 3 wherein the second regions have a characteristic radial extent of about 0.4 microns

6. A photosurface according to claim 3 wherein the second regions have a characteristic radial extent of about 0.3 microns.

7. A photosurface according to claim 3 wherein a distance between two nearest second regions is less than or equal to about 9 microns.

8. A photosurface according to claim 3 wherein a distance between two nearest second regions is less than or equal to about 6 microns.

9. A photosurface according to claim 3 wherein a distance between two nearest second regions is less than or equal to about 4 microns.

10. A photosurface according to claim 3 wherein at least two of the plurality of second regions are electrically connected by a conductor.

11. A photosurface according to claim 10 and comprising a circuit electrically connected to the at least two second regions configured to generate a signal responsive to a total number of electrons that migrate to the at least two second regions.

12. A photosurface according to any claim 1 and having a fill factor equal to or greater than about 40%.

13. A photosurface according to claim 1 and having a fill factor equal to or greater than about 50%.

14. A photosurface according to claim 1 and having a fill factor equal to or greater than about 60%.

15. A photosurface according to claim 1 and having a fill factor equal to or greater than about 75%.

16. A photosurface according to claim 1 wherein the at least one second region comprises a floating diffusion.

17. A photosurface for imaging a scene comprising:

a light sensitive region in which electron-hole pairs are generated responsive to light incident on the photosurface;

at least one charge collecting region which is surrounded by the light sensitive region and in which charge generated in the light sensitive region is stored; and

for each at least one charge collecting region, a transfer gate that completely surrounds the light sensitive region.

18. A photosurface according to claim 17 and comprising a single photogate overlaying the light sensitive region.

19. A photosurface according to claim 17 having a fill factor equal to or greater than about 40%.

20. A CMOS-type light detector cell comprising:

a photogate;

a channel implant in a structure underlying the photogate;

a floating diffusion formed within the channel implant; and

a transfer gate operable to permit electrons accumulated under the photogate to travel through the channel implant to the floating diffusion,

wherein the transfer gate substantially surrounds the floating diffusion and the photogate is a substantially continuous body extending over the channel implant, and includes an opening that surrounds the floating diffusion and the transfer gate.