Image sensor with large-area global shutter contact

• US 9,769,398 B2
• Filed: 01/06/2016
• Issued: 09/19/2017
• Est. Priority Date: 01/06/2016
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Nalla, Ravi Kiran, Price, Raymond Kirk
• Primary Examiner(s): GILES, NICHOLAS G
• Application Number:
  US14/989,091
• Publication Number:
  US 20170195588A1
• Time in Patent Office: 622 Days
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/71 Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors

Abstract

An image sensor comprising a substrate that includes a plurality of photodiodes and a shutter trigger contact is disclosed. The plurality of photodiodes collectively define at least part of a pixel area parallel to a surface of the substrate. The shutter trigger contact is coupled to provide a common shutter trigger signal to the plurality of photodiodes and includes a contiguous conductive region disposed on the substrate substantially coextensively with the pixel area.

Claims

1. An image sensor comprising:

a substrate including a plurality of photodetector regions, the plurality of photodetector regions collectively defining at least part of a pixel area parallel to a surface of the substrate; and

a shutter trigger contact coupled to provide a common shutter trigger signal to the plurality of photodetector regions, the shutter trigger contact including a contiguous conductive region disposed on the substrate so as to be substantially coextensive with the pixel area.

2. The image sensor of claim 1, wherein the contiguous conductive region is disposed on the substrate substantially coextensively with the pixel area along two orthogonal axes parallel to the surface.

3. The image sensor of claim 1, wherein the plurality of photodetector regions that collectively occupy the pixel area comprise an array of at least 25,000 pixels.

4. The image sensor of claim 3, wherein the contiguous conductive region covers an entirety of the pixel area defined collectively by the plurality of photodetector regions.

5. The image sensor of claim 3, wherein a perimeter of the contiguous conductive region is substantially coextensive with a perimeter of the pixel area, and wherein the contiguous conductive region has a plurality of openings aligned respectively with the plurality of photodetector regions.

6. The image sensor of claim 1, wherein at least two of the plurality of photodetector regions, to which the shutter trigger contact is coupled, are not adjacent to each other.

7. The image sensor of claim 1, wherein the contiguous conductive region covers substantially all of a surface of the substrate.

8. The image sensor of claim 1, wherein the contiguous conductive region has openings aligned with the photodetector regions.

9. The image sensor of claim 1, wherein said surface is a front, light-receptive surface of the substrate, the image sensor further comprising a conductive routing layer disposed over the front, light-receptive surface to form input/output contacts for the photodetector regions;

and wherein the shutter trigger contact for the plurality of photodetector regions is disposed on a back surface of the substrate.

10. The image sensor of claim 9, wherein the shutter trigger contact for the plurality of photodetector regions covers substantially all of the back surface of the substrate.

11. The image sensor of claim 1, wherein said surface is a back, light-receptive surface of the substrate, the image sensor further comprising a conductive routing layer disposed over the back, light-receptive surface to form input/output contacts for the photodetector regions;

and wherein the shutter trigger contact for the plurality of photodetector regions is disposed on the back, light-receptive surface.

12. The image sensor of claim 11, wherein the shutter trigger contact for the plurality of photodetector regions has a plurality of openings aligned with the plurality of photodetector regions.

13. The image sensor of claim 1, wherein the shutter trigger contact comprises a stack that includes at least three conductive layers, the stack being formed from at least two kinds of conductive material, and wherein the stack comprises:

an adhesion layer formed from a first type of conductive material and disposed on the substrate to promote adhesion of conductive material to the substrate;

a low resistance conductive layer; and

a diffusion prevention layer formed from a second type of conductive material between the adhesion layer and the low resistance conductive layer, to prevent diffusion into the adhesion layer.

14. An image sensor comprising:

a substrate including a plurality of photodiodes including at least 25,000 photodiodes, the at least 25,000 photodiodes collectively defining at least part of a pixel area parallel to a surface of the substrate; and

a shutter trigger contact coupled to provide a common shutter trigger signal to the plurality of photodiodes, the shutter trigger contact including a contiguous conductive layer disposed on the substrate so that a minimum distance between the shutter trigger contact and each of the plurality of photodiodes is substantially equal.

15. The image sensor of claim 14, wherein the contiguous conductive layer is substantially coextensive with the pixel area.

16. The image sensor of claim 14, wherein the contiguous conductive layer has a plurality of openings aligned respectively with the plurality of photodiodes.

17. The image sensor of claim 14, wherein the shutter trigger contact comprises a metallization stack including the contiguous conductive layer and at least one other conductive layer.

18. The image sensor of claim 17, wherein the metallization stack includes a metal diffusion prevention layer and a low resistance metal layer.

19. The image sensor of claim 17, wherein the contiguous conductive layer is disposed closest to a bottom surface of the substrate that is opposite and parallel to a light-incident surface of the substrate, and wherein the contiguous conductive layer covers substantially all of the bottom surface of the substrate.

20. The image sensor of claim 17, wherein the contiguous conductive layer is disposed closest to a light-incident surface of the substrate.