Process for large-scale ammonothermal manufacturing of semipolar gallium nitride boules

• US 10,145,026 B2
• Filed: 06/03/2013
• Issued: 12/04/2018
• Est. Priority Date: 06/04/2012
• Status: Active Grant

• Current Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Original Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Inventors: D'Evelyn, Mark P., Ehrentraut, Dirk, Kamber, Derrick S., Downey, Bradley C.
• Primary Examiner(s): Langman, Jonathan C
• Application Number:
  US13/908,836
• Publication Number:
  US 20130323490A1
• Time in Patent Office: 2,010 Days
• CPC Class Codes: C30B 19/02 using molten solvents, e.g. flux
• CPC Class Codes: C30B 23/04 Pattern deposit, e.g. by using masks
• CPC Class Codes: C30B 25/04 Pattern deposit, e.g. by using masks
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 7/105 using ammonia as solvent, i.e. ammonothermal processes

Abstract

Methods for large-scale manufacturing of semipolar gallium nitride boules are disclosed. The disclosed methods comprise suspending large-area single crystal seed plates in a rack, placing the rack in a large diameter autoclave or internally-heated high pressure apparatus along with ammonia and a mineralizer, and growing crystals ammonothermally. A bi-faceted growth morphology may be maintained to facilitate fabrication of large area semipolar wafers without growing thick boules.

Claims

1. A crystalline substrate comprising:

at least one planar surface angled by at least about 5 degrees from an m-plane and a c-plane of said crystalline substrate; and

alternating first and second bands laterally disposed on said planar surface, said first band comprising a first impurity concentration, said second band comprising a second impurity concentration, wherein said first impurity concentration is higher than said second concentration.

2. The substrate of claim 1, wherein said planar surface has a semipolar orientation within about 3 degrees of one of {6 0 −

6 −

1}, {5 0 −

5 −

1}, {4 0 −

4 −

1}, {3 0 −

3 −

1}, {5 0 −

5 −

2}, {2 0 −

2 −

1}, {3 0 −

3 −

2}, {4 0 −

4 −

3}, and {5 0 −

5 −

4}.

3. The substrate of claim 1, wherein the length of said planar surface is greater than about 25 millimeters.

4. The substrate of claim 1, wherein said planar surface has a dislocation density below about 10⁷ cm⁻

2.

5. The substrate of claim 4, wherein said dislocation density is below about 10⁶ cm⁻

2.

6. The substrate of claim 5, wherein said dislocation density is below about 10⁵ cm⁻

2.

7. The substrate of claim 6, wherein said dislocation density is below about 10⁴ cm⁻

2.

8. The substrate of claim 1, wherein the crystallographic orientation of said planar surface has a full width at half maximum of a symmetric x-ray rocking curve less than about 150 arc seconds.

9. The substrate of claim 8, wherein said full width at half maximum of a symmetric x-ray rocking curve is less than about 100 arc seconds.

10. The substrate of claim 1, wherein the crystalline substrate has a substantially wurtzite structure, and is substantially free of other crystal structures, wherein the other structures are less than about 1% in volume with respect to a volume of the substantially wurtzite structure.

11. The substrate of claim 1, wherein the crystallographic orientation of said planar surface has a full width at half maximum of a lowest-order asymmetric x-ray rocking curve less than about 150 arc seconds.

12. The substrate of claim 11, wherein said full width at half maximum of a lowest-order asymmetric x-ray rocking curve is less than about 100 arc seconds.

13. The substrate of claim 1, wherein said first and second bands have a period between about 0.01 mm and about 100 mm.

14. The substrate of claim 13, wherein said period is between about 1 mm and about 10 mm.

15. The substrate of claim 1, wherein the ratio of said first and second concentrations is less than 40.

16. The substrate off claim 15, wherein said ratio of said first and second impurity concentrations is less than 10.

17. The substrate of claim 1, wherein said alternating first and second bands comprise at least 4 of each of said first and second bands.

18. The substrate of claim 1, wherein said crystalline substrate comprises a gallium-containing nitride.

19. The substrate of claim 1, wherein said first and second impurity concentrations are greater than about 10¹⁶ cm⁻

3 of at least one impurity selected from O, H, Li, Na, K, F, Cl, Br, I, Si, Ge, Cu, Mn, and Fe.

20. The substrate of claim 19, wherein the at least one impurity is selected from O and H, and the distribution comprises at least 8 of each of said first and second bands, wherein said ratio of said first and second impurity concentrations is less than about 2.

21. The substrate of claim 1, wherein each of said first and second bands comprise a plurality of impurities constituting said first and second impurity concentrations.