Method of growing group III nitride crystals

• US 9,518,340 B2
• Filed: 03/15/2013
• Issued: 12/13/2016
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Seoul Semiconductor Co., Ltd., SixPoint Materials, Inc.
• Inventors: Hashimoto, Tadao, Letts, Edward, Hoff, Sierra
• Primary Examiner(s): Kornakov, Michael
• Assistant Examiner(s): Qi, Hua
• Application Number:
  US13/833,443
• Publication Number:
  US 20140087209A1
• Time in Patent Office: 1,369 Days
• US Class Current: 1/1
• CPC Class Codes: B28D 5/045 by cutting with wires or closed-loop blades B28D5/042 takes precedence
• CPC Class Codes: C30B 25/20 the substrate being of the same materials as the epitaxial layer
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 29/64 Flat crystals, e.g. plates, strips or discs
• CPC Class Codes: C30B 33/06 Joining of crystals
• CPC Class Codes: C30B 7/10 by application of pressure, e.g. hydrothermal processes
• CPC Class Codes: C30B 7/105 using ammonia as solvent, i.e. ammonothermal processes
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02628 using solutions
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/32 the imperfections being within the semiconductor body
• CPC Class Codes: Y10S 117/902 Specified orientation, shape, crystallography, or size of seed or substrate
• CPC Class Codes: Y10T 428/192 Sheets or webs coplanar

Abstract

The present invention provides a method of growing an ingot of group III nitride. Group III nitride crystals such as GaN are grown by the ammonothermal method on both sides of a seed to form an ingot and the ingot is sliced into wafers. The wafer including the first-generation seed is sliced thicker than the other wafers so that the wafer including the first-generation seed does not break. The wafer including the first-generation seed crystal can be used as a seed for the next ammonothermal growth.

Claims

1. A method of making a group III nitride composed of Ga_xAl_yIn_1-x-yN (0≦

x≦

1, 0≦

x+y≦

1) comprising;

(a) growing a first group III nitride crystal on a first face and growing a second group III nitride crystal on a second face of a first-generation seed to form a first ingot of group III nitride;

(b) slicing the first ingot into a first, second, and third wafer;

wherein the first wafer includes the first-generation seed, and the first wafer has a thickness greater than a thickness of each of the second wafer and the third wafer, and wherein the thickness of the first wafer containing the first-generation seed is large enough to avoid breaking of the first wafer.

2. A method according to claim 1 and further comprising growing a third group III nitride crystal on a first face of said first wafer and a fourth group III nitride crystal on a second face of said first wafer.

3. A method according to claim 2, wherein cracks exposed on the surface of the first wafer including the first-generation seed are buried during the next growth.

4. A method according to claim 1, wherein both surfaces of the first wafer which includes the first-generation seed are covered with group III nitride crystals grown on the first-generation seed.

5. A method according to claim 4, wherein the group III nitride crystals are grown in supercritical ammonia.

6. A method according to claim 1, wherein the ingot is sliced into wafers with a multiple wire saw having a different wire pitch for the wafer which includes the first-generation seed.

7. A method according to claim 1, wherein the first-generation seed comprises two pieces of c-plane (misorientation within +/−

10 degrees) group III nitride wafers with group III polar surface facing together so that nitrogen polar surfaces are exposed on both faces.

8. A method according to claim 7, wherein the in-plane crystallographic orientation of the c-plane (misorientation within +/−

10 degrees) group III nitride wafers matches together.

9. A method according to claim 7, wherein cracks generated in the group III nitride crystals do not propagate through the interface of the c-plane (misorientation within +/−

10 degrees) group III nitride wafers.

10. A method according to claim 7, wherein the shape and size of the c-plane (misorientation within +/−

10 degrees) group III nitride wafers matches so that minimum area of group III polar surface is exposed.

11. A method according to claim 1, wherein the first-generation seed comprises two layers of c-plane (misorientation within +/−

10 degrees) group III nitride wafers with group III polar surface facing together so that nitrogen polar surfaces are exposed on both faces, each layer consists of multiple pieces of c-plane (misorientation within +/−

10 degrees) group III nitride wafers arrayed on edges, the edges of the c-plane (misorientation within +/−

10 degrees) group III nitride wafers on the first layer do not correspond to the edges of the c-plane (misorientation within +/−

10 degrees) group III nitride wafers on the second layer, and in-plane crystallographic orientation of all wafers on the first and second layer matches.

12. A method according to claim 11, wherein cracks generated in the group III nitride crystals do not propagate through the interface of the two layers of c-plane (misorientation within +/−

10 degrees) group III nitride wafers.

13. A method according to claim 11, wherein the size and shape of each layer matches so that minimum area of group III polar surface is exposed.

14. A method according to claim 13, wherein the edge of the longer dimension of each layer is aligned to a-plane (misorientation within +/−

10 degrees).

15. A method according to claim 1, wherein the group III nitride comprises gallium nitride.

16. A method according to claim 1 wherein the second wafer is formed from the first group III nitride crystal and the third wafer is formed from the second group III nitride crystal.

17. A method according to claim 1 wherein the first group III nitride crystal has a crystalline structure polarity and the second group III nitride crystal has said crystalline structure polarity.

18. A method of fabricating group III nitride wafers composed of Ga_xAl_yIn_1-x-yN (0≦

x≦

1, 0≦

x+y≦

1) comprising;

(a) growing group III nitride crystals on both faces of a seed of group III nitride to form an ingot of group III nitride;

(b) slicing the ingot of group III nitride into wafers with a multiple wire saw wherein the pitch of the wire is changed so that the wafer which includes the seed is thicker than other wafers sliced from the ingot.

19. A method according to claim 18, wherein the thickness of the wafer which includes the seed crystal is large enough to avoid breaking of the wafer.

20. A method according to claim 18, wherein the group III nitride crystals are grown in supercritical ammonia.

21. A method according to claim 18, wherein the group III nitride comprises gallium nitride.