Low dark current image sensors with epitaxial SiC and/or carbonated channels for array transistors

• US 20060033132A1
• Filed: 08/08/2005
• Published: 02/16/2006
• Est. Priority Date: 08/16/2004
• Status: Active Grant

• Current Assignee: Chandra Mouli
• Original Assignee: Chandra Mouli
• Inventors: Mouli, Chandra
• Granted Patent: US 7,585,707 B2
• Time in Patent Office: Days
• US Class Current: 257/292
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14654 Blooming suppression
• CPC Class Codes: H01L 27/14689 MOS based technologies

Abstract

A pixel cell having a substrate with a isolation channel formed of higher carbon concentrate such as SiC or carbonated silicon. The channel comprising SiC or carbonated silicon is provided over the substrate of the pixel cell to reduce the dark current leakage.

Claims

1-18. -18. (canceled)

19. A method of forming a pixel cell, the method comprising the steps of:

forming a substrate;

forming a nitride layer over said substrate at selected location to form an exposed pattern; and

forming an isolation channel layer over the substrate at locations corresponding to said exposed pattern.

20. The method of claim 19 wherein said isolation channel layer is SiC.

21. The method of claim 19 wherein said isolation channel layer is Carbonated channel Silicon.

22. The method of claim 19 wherein said isolation channel is formed to a depth of approximately 100 Å

to approximately 500 Å

.

23. The method of claim 19, wherein said isolation channel layer is formed to a depth of approximately 250 Å

.

24. The method of claim 19, wherein said isolation channel layer is formed in a transistor region of said pixel cell.

25. The method of claim 22, wherein said isolation channel layer is formed in a photo-conversion region of said pixel cell.

26. The method of claim 22, wherein said isolation channel layer is formed in a periphery region of said pixel cell.

27. The method of claim 19, wherein said isolation channel layer is formed over a source and drain region of said pixel cell.

28. The method of claim 27, wherein said isolation channel layer is formed in said photo conversion region of said pixel cell.

29. A method of forming a pixel cell, the method comprising the steps of:

forming a substrate; and

forming a carbon rich isolation channel layer over the substrate.

30. The method of claim 29, further comprising the step of forming a nitride layer over the substrate before the step of forming the isolation channel layer.

31. The method of claim 30, wherein said nitride layer is selectively formed over said substratre.

32. The method of claim 30, wherein said nitride layer is selectively formed over the substrate to expose a transistor region.

33. The method of claim 30, wherein said nitride layer is selectively formed over the substrate to expose a photo-conversion region.

34. The method of claim 30, wherein said nitride layer is selectively formed over the substrate to expose a periphery region.

35. The method of claim 30, wherein said step of forming said carbon rich isolation channel layer is effectuated through epitaxial growth.

36. The method of claim 31, wherein said step of forming said carbon rich isolation channel layer through epitaxial growth is performed at low temperature.

37. The method of claim 30, further comprising the step of forming said nitride layer over the substrate after the step of forming the isolation channel layer.

38. The method of claim 37, further comprising the step of forming a seed layer for gate oxidation over said nitride layer.

39. The method of claim 37, wherein said seed layer is formed from silicon.

40. The method of claim 38, further comprising the step of forming a gate oxidation layer over said layer.

41. The method of claim 40, wherein said gate oxidation layer is formed by rapid thermal oxidation.

42. The method of claim 41, wherein said gate oxidation layer is formed by in-site stem generation.

43-55. -55. (canceled)