CHAMFERED FREESTANDING NITRIDE SEMICONDUCTOR WAFER AND METHOD OF CHAMFERING NITRIDE SEMICONDUCTOR WAFER

• US 20090218659A1
• Filed: 05/06/2009
• Published: 09/03/2009
• Est. Priority Date: 04/02/2003
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Irikura, Masato, NAKAYAMA, Masahiro
• Granted Patent: US 8,022,438 B2
• Time in Patent Office: Days
• US Class Current: 257/615
• CPC Class Codes: B24B 21/002 for grinding edges or bevels
• CPC Class Codes: B24B 9/065 of thin, brittle parts, e.g. semiconductors, wafers
• CPC Class Codes: H01L 21/02021 Edge treatment, chamfering
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body

Abstract

Technology of making freestanding gallium nitride (GaN) wafers has been matured at length. Gallium nitride is rigid but fragile. Chamfering of a periphery of a GaN wafer is difficult. At present edges are chamfered by a rotary whetstone of gross granules with weak pressure. Minimum roughness of the chamfered edges is still about Ra 10 μm to Ra 6 μm. The large edge roughness causes scratches, cracks, splits or breaks in transferring process or wafer process. A wafer of the present invention is bevelled by fixing the wafer to a chuck of a rotor, bringing an edge of the wafer into contact with an elastic whetting material having a soft matrix and granules implanted on the soft matrix, rotating the wafer and feeding the whetting material. Favorably, several times of chamfering edges by changing the whetting materials of smaller granules are given to the wafer. The chamfering can realize small roughness of Ra 10 nm and Ra 5 μm at edges of wafers.

Claims

1-20. -20. (canceled)

21. A chamfered freestanding nitride semiconductor wafer having a peripheral edge having roughness of between Ra0.1 μ

m and Ra5 μ

m.

22. The chamfered freestanding nitride semiconductor wafer as claimed in claim 21, wherein the nitride semiconductor wafer is a GaN wafer.

23. The chamfered freestanding nitride semiconductor wafer as claimed in claim 21, wherein the nitride semiconductor wafer is an AlN wafer.

24. The chamfered freestanding nitride semiconductor wafer as claimed in claim 21, wherein the nitride semiconductor wafer is an InN wafer.