AVALANCHE PHOTODIODE FOR DETECTING ULTRAVIOLET RADIATION AND MANUFACTURING METHOD THEREOF

• US 20170098730A1
• Filed: 04/28/2016
• Published: 04/06/2017
• Est. Priority Date: 10/06/2015
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Sutera, Dario, Mazzillo, Massimo Cataldo, Sciuto, Antonella
• Granted Patent: US 10,461,209 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 31/022416 comprising ring electrodes
• CPC Class Codes: H01L 31/107 the potential barrier working in avalanche mode, e.g. avalanche photodiodes
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof

Abstract

An avalanche photodiode for detecting ultraviolet radiation, including: a silicon carbide body having a first type of conductivity, which is delimited by a front surface and forms a cathode region; an anode region having a second type of conductivity, which extends into the body starting from the front surface and contacts the cathode region; and a guard ring having the second type of conductivity, which extends into the body starting from the front surface and surrounds the anode region.

Claims

1. An avalanche photodiode for detecting ultraviolet radiation, comprising:

a semiconductor body having a first type of conductivity and a front surface and forms a cathode region;

an anode region having a second type of conductivity, which extends into said body starting from the front surface and contacts the cathode region; and

a guard ring having the second type of conductivity, which extends into said body starting from the front surface and completely laterally surrounds the anode region.

2. The photodiode according to claim 1, wherein the guard ring has a doping level lower than a doping level of the anode region.

3. The photodiode according to claim 1, wherein the anode region has a thickness comprised between 0.05 μ

m and 0.25 μ

m.

4. The photodiode according to claim 1, wherein the body comprises a weakly doped region and a heavily doped region, the heavily doped region being arranged between the anode region and the weakly doped region, with which the heavily doped region is in direct contact.

5. The photodiode according to claim 4, wherein said weakly doped region is an intrinsic semiconductor region.

6. The photodiode according to claim 4, wherein said weakly doped region has a doping level not higher than 1·

10¹⁵ cm<sup>−

3</sup>.

7. The photodiode according to claim 1, further comprising:

a trench which extends through the body starting from the front surface and completely laterally surrounds the guard ring; and

a conductive region extending within the trench.

8. The photodiode according to claim 1, comprising an antireflective structure which extends in contact with the anode region and has a transmittance at 290 nm of at least 80%.

9. A photodiode array comprising a plurality of avalanche photodiodes formed in a semiconductor body having a first type of conductivity and a front surface, each avalanche photodiode including:

a cathode region;

an anode region having a second type of conductivity, which extends into said body starting from the front surface and contacts the cathode region; and

a guard ring having the second type of conductivity, which extends into said body starting from the front surface and completely laterally surrounds the anode region.

10. The photodiode array according to claim 9, wherein the guard ring has a doping level lower than a doping level of the anode region.

11. The photodiode array according to claim 9, wherein the body comprises a weakly doped region and a heavily doped region, the heavily doped region being arranged between the anode region and the weakly doped region, with which the heavily doped region is in direct contact.

12. The photodiode array according to claim 9, further comprising:

a trench which extends through the body starting from the front surface and completely laterally surrounds the guard ring; and

a conductive region extending within the trench.

13. A system for detecting ultraviolet radiation, comprising:

a processing unit; and

a photodiode array coupled to said processing unit and including a plurality of avalanche photodiodes formed in a semiconductor body having a first type of conductivity and a front surface, each avalanche photodiode including;

a cathode region;

an anode region having a second type of conductivity, which extends into said body starting from the front surface and contacts the cathode region; and

a guard ring having the second type of conductivity, which extends into said body starting from the front surface and completely laterally surrounds the anode region.

14. The system according to claim 13, wherein the guard ring has a doping level lower than a doping level of the anode region.

15. The system according to claim 13, wherein the body comprises a weakly doped region and a heavily doped region, the heavily doped region being arranged between the anode region and the weakly doped region, with which the heavily doped region is in direct contact.

16. The system according to claim 13, wherein the photodiode array includes:

a trench which extends through the body starting from the front surface and completely laterally surrounds the guard ring; and

a conductive region extending within the trench.

17. A method, comprising:

manufacturing an avalanche photodiode for detecting ultraviolet radiation, the manufacturing including;

in a semiconductor body having a first type of conductivity, which is delimited by a front surface and includes a cathode region, forming an anode region having a second type of conductivity, which extends into said body starting from the front surface and contacts the cathode region; and

forming a guard ring having the second type of conductivity, which extends into said body starting from the front surface and completely laterally surrounds the anode region.

18. The method according to claim 17, wherein forming the anode region comprises:

forming a first implanted region by carrying out a first selective implantation of dopant ion species having the second type of conductivity within said body; and

carrying out a first thermal treatment on the first implanted region.

19. The method according to claim 18, wherein forming the anode region further comprises the step of forming on the front surface a carbon layer after carrying out said first selective implantation and before carrying out said first thermal treatment.

20. The method according to claim 18, wherein forming the guard ring comprises:

after forming the anode region, forming a second implanted region by carrying out a second selective implantation of dopant ion species having the second type of conductivity within said body; and

carrying out a second thermal treatment of the second implanted region.

21. The method according to claim 18, wherein forming the guard ring comprises:

after forming the first implanted region and before carrying out the first thermal treatment, forming a second implanted region by carrying out a second selective implantation of dopant ion species having the second type of conductivity within said body.

22. The method according to claim 21, further comprising forming on the front surface a carbon layer, after carrying out said first and second selective implantations and before carrying out said first thermal treatment.

23. The method according to claim 17, further comprising forming said body with a weakly doped region and a heavily doped region, the heavily doped region being arranged between the anode region and the weakly doped region, with which the heavily doped region is in direct contact.

24. The method according to claim 17, further comprising:

etching, within said body, a trench; and

forming, within the trench, a conductive region.

25. The method according to 17, further comprising forming on the anode region an antireflective structure with a transmittance at 290 nm of at least 80%.