Method and apparatus for collecting photons in a solid state imaging sensor

• US 20060138495A1
• Filed: 02/21/2006
• Published: 06/29/2006
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Li, Jiutao, Li, Jin
• Granted Patent: US 7,358,103 B2
• Time in Patent Office: Days
• US Class Current: 257/292
• CPC Class Codes: H01L 27/14601 Structural or functional details thereof
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

A photon collector has a reflecting metal layer to increase photon collection efficiency in a solid state imaging sensor. The reflecting metal layer reflects incident light internally to a photosensor. A plurality of photon collectors is formed in a wafer substrate over an array of photosensors. The photon collector is formed in an opening in an insulating layer provided over each photosensor.

Claims

1-23. -23. (canceled)

24. A method of fabricating an imaging device, said method comprising:

forming a plurality of photosensors on a wafer;

forming a structure with sidewalls in an insulating layer on said wafer provided over said photosensors; and

depositing a reflecting material on said sidewalls of each structure.

25. A method according to claim 24, wherein said reflecting material is a metal.

26. A method according to claim 25, wherein said reflecting material is aluminum.

27. A method according to claim 25, wherein said reflecting material is silver.

28. A method according to claim 27, the method further including forming a barrier layer between said silver and said insulating layer.

29. A method according to claim 24, wherein the diameter of an upper portion of each structure is greater than the diameter at the base of each said structure.

30. A method according to claim 24, wherein said sidewalls of each structure are selected from the group consisting of substantially perpendicular, substantially diagonal, curved surfaces, and combinations thereof.

31. A method according to claim 24, further comprising depositing said reflecting layer through a collimated structure.

32. A method according to claim 31, wherein said wafer is held at an angle to the collimation angle of said structure.

33. A method according to claim 32, wherein the angle is selected such that reflecting material is not deposited over said photosensors.

34. A method according to claim 24, further comprising providing an optically transparent material contained within the sidewalls of each said structure.

35. A method according to claim 34, wherein the optically transparent material is selected from the group consisting of spun-on glass and photoresist.

36. A method of fabricating an imaging device, said method comprising:

forming a photodiode beneath an insulating layer;

providing an etch stop layer over said photodiode;

etching an opening in the semiconductor substrate above the photodiode to said etch stop layer;

depositing a light-reflecting metal on sidewalls of said opening with a collimated source of said light-reflecting metal; and

filling said opening with a optically transparent material.

37-41. -41. (canceled)