Stacked-chip backside-illuminated SPAD sensor with high fill-factor

• US 10,153,310 B2
• Filed: 07/18/2016
• Issued: 12/11/2018
• Est. Priority Date: 07/18/2016
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Zhang, Bowei, Venezia, Vincent, Chen, Gang, Tai, Dyson H., Mao, Duli
• Primary Examiner(s): Chen, David
• Application Number:
  US15/213,082
• Publication Number:
  US 20180019268A1
• Time in Patent Office: 876 Days
• Field of Search: 257292, 257438, 257603, 257E21357, 257E29335, 257E31063, 438 91, 438380
• CPC Class Codes: G01J 2001/442 Single-photon detection or photon counting
• CPC Class Codes: H01L 27/1443 with at least one potential jump or surface barrier
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 31/02027 for devices working in avalanche mode
• CPC Class Codes: H01L 31/02327 the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/107 the potential barrier working in avalanche mode, e.g. avalanche photodiodes

Abstract

A photon detection device includes a single photon avalanche diode (SPAD) disposed in a semiconductor layer. A guard ring structure is disposed in the semiconductor layer surrounding the SPAD to isolate the SPAD. A well region is disposed in the semiconductor layer surrounding the guard ring structure and disposed along an outside perimeter of the photon detection device. A contact region is disposed in the well region only in a corner region of the outside perimeter such that there is no contact region disposed along side regions of the outside perimeter. A distance between an inside edge of the guard ring structure and the contact region in the corner region of the outside perimeter is greater than a distance between the inside edge of the guard ring structure and the side regions of the outside perimeter such that an electric field distribution is uniform around the photon detection device.

Claims

1. A photon detection device, comprising:

a single photon avalanche diode (SPAD) disposed in an active breakdown region of a first semiconductor layer;

a guard ring structure disposed in the first semiconductor layer surrounding the SPAD to isolate the SPAD inside the guard ring structure;

a well region disposed in the first semiconductor layer surrounding the guard ring structure and disposed along an outside perimeter of the photon detection device in the first semiconductor layer; and

a contact region disposed in the well region only in a corner region of the outside perimeter such that there is no contact region disposed along side regions of the outside perimeter,

wherein the well region is non-circular in shape in order to include the corner region and the side regions surrounding the guard ring structure such that a first distance between an inside edge of the guard ring structure and the contact region in the corner region of the outside perimeter is greater than a second distance between the inside edge of the guard ring structure and the side regions of the outside perimeter such that an electric field distribution is uniform around the photon detection device, wherein the first semiconductor layer comprises a p−

doped epitaxial layer, wherein the well region comprises a p−

doped semiconductor region, and wherein the contact region comprises a p+ doped semiconductor region.

2. The photon detection device of claim 1, wherein the contact region is a first contact region of a plurality of contact regions, wherein the corner region is a first corner region of a plurality of corner regions of the outside perimeter of the photon detection device, wherein each one of the plurality of contact regions is disposed in the well region only in a respective one of the plurality of corner regions of the outside perimeter such that there are no contact regions disposed along the side regions of the outside perimeter.

3. The photon detection device of claim 2, wherein the first distance is a contact distance between the inside edge of the guard ring structure and a respective one of the plurality of contact regions, wherein the contact distance is greater than the second distance between the inside edge of the guard ring structure and the side regions of the outside perimeter such that the electric field distribution is uniform around the photon detection device.

4. The photon detection device of claim 1, wherein the well region is provided with a retrograde p-well implant only along the side regions of the outside perimeter.

5. The photon detection device of claim 1, wherein the contact region in the corner region of the outside perimeter is coupled to a high negative bias voltage, wherein a surface voltage of the well region along the side regions of the outside perimeter is less negative than the high negative bias voltage.

6. The photon detection device of claim 1, wherein the inside edge of the guard ring structure includes an n−

doped region surrounding the SPAD in the first semiconductor layer.

7. The photon detection device of claim 1, wherein the guard ring structure is laterally defined in the first semiconductor layer between the SPAD and the well region.

8. The photon detection device of claim 7, wherein the SPAD includes a multiplication junction defined at an interface between an n+ doped layer and a p doped layer of the SPAD in the active breakdown region.

9. The photon detection device of claim 1, wherein the SPAD is formed in a front side of the first semiconductor layer, and wherein the SPAD is optically coupled to receive the photons through a back side of the first semiconductor layer.

10. The photon detection device of claim 9, wherein the first semiconductor layer is included in a first semiconductor device wafer, wherein the first semiconductor device wafer is stacked with a second semiconductor device wafer including support circuitry coupled to the SPAD, and wherein the first and second semiconductor device wafers are coupled together in a stacked chip system.

11. The photon detection device of claim 1, wherein the contact region is shared with a second well region of a second photon detection device in the first semiconductor layer.

12. A photon sensing system, comprising:

a photon detection array having a plurality of photon detection devices, wherein each one of the photon detection devices includes;

a single photon avalanche diode (SPAD) disposed in an active breakdown region of a first semiconductor layer;

a guard ring structure disposed in the first semiconductor layer surrounding the SPAD to isolate the SPAD inside the guard ring structure;

a well region disposed in the first semiconductor layer surrounding the guard ring structure and disposed along an outside perimeter of the photon detection device in the first semiconductor layer; and

a contact region disposed in the well region only in a corner region of the outside perimeter such that there is no contact region disposed along side regions of the outside perimeter,

wherein the well region is non-circular in shape such that the well region includes the corner region and the side regions surrounding the guard ring structure, such that a first distance between an inside edge of the guard ring structure and the contact region in the corner region of the outside perimeter is greater than a second distance between the inside edge of the guard ring structure and the side regions of the outside perimeter such that an electric field distribution is uniform around the photon detection device, wherein the first semiconductor layer comprises a p−

doped epitaxial layer, wherein the well region comprises a p−

doped semiconductor region, and wherein the contact region comprises a p+ doped semiconductor region; and

a support circuitry coupled to the photon detection array to support operation of the photon detection array, wherein the support circuitry is disposed in a second semiconductor layer.

13. The photon sensing system of claim 12, wherein the first semiconductor layer is included in a first semiconductor device wafer, wherein the first semiconductor device wafer is stacked with a second semiconductor device wafer including the second semiconductor layer, and wherein the first and second semiconductor device wafers are coupled together in a stacked chip system.

14. The photon sensing system of claim 12, wherein the contact region is a first contact region of a plurality of contact regions, wherein the corner region is a first corner region of a plurality of corner regions of the outside perimeter of the photon detection device, wherein each one of the plurality of contact regions is disposed in the well region only in a respective one of the plurality of corner regions of the outside perimeter such that there are no contact regions disposed along the side regions of the outside perimeter.

15. The photon sensing system of claim 14, wherein the first distance is a contact distance between the inside edge of the guard ring structure and a respective one of the plurality of contact regions, wherein the contact distance is greater than the second distance between the inside edge of the guard ring structure and the side regions of the outside perimeter such that the electric field distribution is uniform around the photon detection device.

16. The photon sensing system of claim 12, wherein the well region is provided with a retrograde p-well implant only along the side regions of the outside perimeter.

17. The photon sensing system of claim 12, wherein the contact region in the corner region of the outside perimeter is coupled to a high negative bias voltage, wherein a surface voltage of the well region along the side regions of the outside perimeter is less negative than the high negative bias voltage.

18. The photon sensing system of claim 12, wherein the inside edge of the guard ring structure includes an n−

doped region surrounding the SPAD in the first semiconductor layer.

19. The photon sensing system of claim 12, wherein the guard ring structure is laterally defined in the first semiconductor layer between the SPAD and the well region.

20. The photon sensing system of claim 19, wherein the SPAD includes a multiplication junction defined at an interface between an n+ doped layer and a p doped layer of the SPAD in the active breakdown region.

21. The photon sensing system of claim 12, wherein the SPAD is formed in a front side of the first semiconductor layer, and wherein the SPAD is optically coupled to receive the photons through a back side of the first semiconductor layer.

22. The photon sensing system of claim 12, wherein the contact region is coupled to a second well region of a second photon detection device in the first semiconductor layer.