Method of fabricating group III nitride with gradually degraded crystal structure

Patent metadata

Field	Value
Publication number	US-9822465-B2
Application number	US-201514957546-A
Country	US
Kind code	B2
Filing date	Dec 2, 2015
Priority date	Apr 7, 2006
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

In one instance, the invention provides a group III nitride crystal having a first side exposing nitrogen polar c-plane of single crystalline or highly oriented polycrystalline group III nitride and a second side exposing group III polar surface, polycrystalline phase, or amorphous phase of group III nitride. Such structure is useful as a seed crystal for ammonothermal growth of bulk group III nitride crystals. The invention also discloses the method of fabricating such crystal. The invention also discloses the method of fabricating a bulk crystal of group III nitride by ammonothermal method using such crystal.

First claim

What is claimed is:

1. A method of fabricating a group III nitride crystal comprising:
(a) growing a single crystalline or a oriented polycrystalline group III nitride layer on a substrate, wherein the exposed surface of the layer is group III polar c plane;
(b) further growing single crystalline or oriented polycrystalline group III nitride having gradually degraded crystal structure such that the exposed surface of the crystal becomes a group III polar c-plane, polycrystalline phase or amorphous phase;
(c) removing the substrate to obtain a crystal having a first nitrogen polar c-plane surface and a second group III polar c-plane surface, polycrystalline phase or amorphous phase of the group III nitride.

2. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (a) and (b) are conducted with hydride vapor phase epitaxy.

3. A method of fabricating a group III nitride crystal according to claim 2 , wherein the substrate is a heterogeneous substrate.

4. A method of fabricating a group III nitride crystal according to claim 1 , wherein the substrate is a heterogeneous substrate.

5. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (c) comprises self-separation of the substrate upon or after cooling.

6. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (c) comprises grinding of the substrate.

7. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (c) comprises laser lift-off of the substrate.

8. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (b) is conducted at lower temperature than that of step (a).

9. A method of fabricating a group III nitride crystal according to claim 8 , wherein the temperature in the step (b) is gradually decreased during growth.

10. A method of fabricating a group III nitride crystal according to claim 9 , wherein the temperature in the step (b) is decreased linearly during growth.

11. A method of fabricating a group III nitride crystal according to claim 2 , wherein the step (b) is conducted at lower temperature than that of step (a).

12. A method of fabricating a group III nitride crystal according to claim 11 , wherein the temperature in the step (b) is gradually decreased during growth.

13. A method of fabricating a group III nitride crystal according to claim 12 , wherein the temperature in the step (b) is decreased linearly during growth.

14. A method of fabricating a group III nitride crystal according to claim 3 , wherein the step (b) is conducted at lower temperature than that of step (a).

15. A method of fabricating a group III nitride crystal according to claim 14 , wherein the temperature in the step (b) is gradually decreased during growth.

16. A method of fabricating a group III nitride crystal according to claim 15 , wherein the temperature in the step (b) is decreased linearly during growth.

17. A method of fabricating a group III nitride crystal according to claim 1 , wherein the step (b) is conducted at higher oxygen concentration than that of step (a).

18. A method of fabricating a group III nitride crystal according to claim 8 , wherein the oxygen concentration in the step (b) is gradually increased during growth.

19. A method of fabricating a group III nitride crystal according to claim 1 , further comprising the following steps;
(a) grinding the second surface;
(b) grinding the first surface;
(c) lapping the first surface.

20. A method of fabricating a group III nitride crystal according to claim 1 , wherein the group III nitride is GaN.

21. A method according to claim 1 , wherein the group III nitride is GaN.

Assignees

• Sixpoint Mat Inc
• Seoul Semiconductor Co Ltd

Inventors

• Hashimoto Tadao

Classifications

• C01B21/0632

  with gallium, indium or thallium · CPC title

• C30B25/02

  Epitaxial-layer growth · CPC title

• C30B7/105 Primary

  using ammonia as solvent, i.e. ammonothermal processes · CPC title

• C01P2004/60

  Particles characterised by their size · CPC title

• C30B29/406

  Gallium nitride · CPC title