Shallow junction photodiode for detecting short wavelength light

• US 8,912,615 B2
• Filed: 01/24/2013
• Issued: 12/16/2014
• Est. Priority Date: 01/24/2013
• Status: Active Grant

• Current Assignee: OSI Optoelectronics, Inc. (OSI Systems Incorporated)
• Original Assignee: OSI Optoelectronics, Inc. (OSI Systems Incorporated)
• Inventors: Bui, Peter Steven, Taneja, Narayan Dass
• Primary Examiner(s): Nguyen, Thinh T
• Application Number:
  US13/749,616
• Publication Number:
  US 20140203386A1
• Time in Patent Office: 691 Days
• Field of Search: 257/431, 257/432, 257/443, 257/E21.001, 438/48, 438/54, 438/66, 438/69, 438/87
• US Class Current: 257/431
• CPC Class Codes: H01L 27/1461 characterised by the photosensitive area
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14658 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H01L 27/14663 Indirect radiation imagers, e.g. using luminescent members
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 27/14687 Wafer level processing
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 31/035272 characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/103 the potential barrier being of the PN homojunction type
• CPC Class Codes: H01L 31/1185 of the shallow PN junction detector type
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table

Abstract

The present invention is a photodiode or photodiode array having improved ruggedness for a shallow junction photodiode which is typically used in the detection of short wavelengths of light. In one embodiment, the photodiode has a relatively deep, lightly-doped P zone underneath a P+ layer. By moving the shallow junction to a deeper junction in a range of 2-5 μm below the photodiode surface, the improved device has improved ruggedness, is less prone to degradation, and has an improved linear current.

Claims

1. A photodiode having a top surface defined by at least one SiO₂ layer comprising:

a low resistivity substrate;

a high resistivity silicon layer positioned atop the low resistivity substrate and below the top surface of the photodiode;

a first P doped zone within the high resistivity silicon layer, wherein the first P doped zone has a thickness of 2-5 μ

m;

a first P+ doped zone positioned between the top of the first P doped zone and the top of the photodiode.

2. The photodiode of claim 1 wherein the low resistivity substrate has a thickness in a range of 150 μ

m to 350 μ

m.

3. The photodiode of claim 1 wherein the low resistivity substrate is doped n+.

4. The photodiode of claim 1 wherein the high resistivity silicon layer has a thickness in a range of 10 μ

m to 100 μ

m.

5. The photodiode of claim 1 wherein the high resistivity silicon layer is doped n.

6. The photodiode of claim 1 wherein the first P+ doped zone and a portion of the first P doped zone is surrounded by P+ doped ring.

7. The photodiode of claim 1 further comprising a first N+ region extending throughout the thickness of the high resistivity silicon layer.

8. The photodiode of claim 7 further comprising a second N+ region extending throughout the thickness of the high resistivity silicon layer, wherein the second N+ region is separated from the first N+ region by a third region and wherein the first P doped zone and first P+ doped zone is located in the third region.

9. The photodiode of claim 8 further comprising a third N+ region extending throughout the thickness of the high resistivity silicon layer, wherein the third N+ region is separated from the second N+ region by a fourth region.

10. The photodiode of claim 1 further comprising a second P doped zone within said fourth region in the high resistivity silicon layer, wherein the second P doped zone has a thickness of 2-5 μ

m.

11. The photodiode of claim 2 further comprising a second P+ doped zone positioned between the top of the second P doped zone and the top of the photodiode in the fourth region.

12. The photodiode of claim 1 wherein all of the first P+ doped zone and a portion of the first P doped zone is surrounded by P+ doped ring.

13. The photodiode of claim 1 wherein all of the second P+ doped zone and a portion of the second P doped zone is surrounded by P+ doped ring.

14. The photodiode of claim 1 further comprising an anode and a cathode on the top surface of the photodiode.

15. The photodiode of claim 1 further comprising an anode on the top surface of the photodiode and a cathode on a backside of the photodiode.

16. The photodiode of claim 1 further comprising an anode on the top surface of the photodiode, a cathode on the top surface of the photodiode, and a cathode on a backside of the photodiode.