Deep diffused thin photodiodes

• US 20070090394A1
• Filed: 10/25/2005
• Published: 04/26/2007
• Est. Priority Date: 10/25/2005
• Status: Active Grant

• Current Assignee: OSI Optoelectronics, Inc. (OSI Systems Incorporated)
• Original Assignee: UDT Sensors, Inc. (OSI Systems Incorporated)
• Inventors: Bui, Peter, Taneja, Narayan
• Granted Patent: US 7,576,369 B2
• Time in Patent Office: Days
• US Class Current: 257/127
• CPC Class Codes: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 31/0352 characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
• CPC Class Codes: H01L 31/103 the potential barrier being of the PN homojunction type

Abstract

This invention comprises photodiodes, optionally organized in the form of an array, including p+ deep diffused regions or p+ and n+ deep diffused regions. More specifically, the invention permits one to fabricate thin 4 inch and 6 inch wafer using the physical support provided by a n+ deep diffused layer and/or p+ deep diffused layer. Consequently, the present invention delivers high device performances, such as low crosstalk, low radiation damage, high speed, low leakage dark current, and high speed, using a thin active layer.

Claims

1. A photodiode comprising:

a substrate with at least a front side and a back side;

a passivation layer proximate to the front side;

an active high resistivity layer proximate to said passivation layer comprising at least five regions of alternating conductivity type;

an n+ deep drive in layer proximate to the active high resistivity layer;

an anti-reflective layer proximate to said n+ deep drive in layer; and

a plurality of contact electrodes in electrical communication with each of said five regions of alternating conductivity type.

2. The photodiode of claim 1 wherein the passivation layer comprises SiO₂/Si₃N₄

3. The photodiode of claim 1 wherein the high resistivity layer comprises n-type silicon.

4. The photodiode of claim 1 wherein the high resistivity layer comprises a thickness of approximately 130 μ

m.

5. The photodiode of claim 1 wherein the high resistivity layer of approximately 10 μ

m.

6. The photodiode of claim 1 wherein the five regions of alternating conductivity type comprises a first n+ region adjacent to a first deep diffused p+ region adjacent to a second n+ region adjacent to a second deep diffused p+ region adjacent to a third n+ region.

7. The photodiode of claim 6 wherein the five regions of alternating conductivity type comprise a thickness of approximately 40 μ

m.

8. The photodiode of claim 1 wherein the n+ deep drive in layer comprises a thickness of approximately 40 μ

m.

9. The photodiode of claim 1 wherein the five regions of alternating conductivity type comprises a first deep diffused n+ region adjacent to a first deep diffused p+ region adjacent to a second deep diffused n+ region adjacent to a second deep diffused p+ region adjacent to a third deep diffused n+ region.

10. The photodiode of claim 9 wherein the five regions of alternating conductivity type comprise a thickness of approximately 140 μ

m to 200 μ

m.

11. The photodiode of claim 10 wherein the n+ deep drive in layer comprises a thickness of approximately 0.5 μ

m.

12. The photodiode of claim 1 wherein the n+ deep drive-in layer comprises a n+ concentration of approximately 10¹⁶.

13. The photodiode of claim 1 wherein the n+ deep drive-in layer comprises a n+ concentration of approximately 1016 to 10¹⁹.

14. A photodiode array comprising photodiodes of any one of claims 1-13.

15. A computed tomography system comprising photodiodes of any one of claims 1-13.