# US 8,465,588 B2 · Ammonothermal method for growth of bulk gallium nitride

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- Number: US 8,465,588 B2
- Document ID: US8465588B2
- Status: Granted
- Kind: B2
- Application number: 13/175,739
- Filed: 2011-07-01
- Published: 2011-10-27
- Granted: 2013-06-18
- Earliest claimed: 2008-09-11
- Assignees: Soraa, Inc.
- Applicants: Christiane Poblenz; James S. Speck; Derrick S. Kamber
- Inventors: Christiane Poblenz; James S. Speck; Derrick S. Kamber
- Web page: https://patentgrep.com/patent/US8465588B2

## CPC

- C30B 23/02: Epitaxial-layer growth
- C30B 7/105: {using ammonia as solvent, i.e. ammonothermal processes}
- C30B 25/02: Epitaxial-layer growth
- C30B 29/403: {AIII-nitrides}
- C30B 29/406: {Gallium nitride}
- H10P 14/2901: {Materials}
- H10P 14/3416: {Nitrides}
- H10P 14/3466: {Crystal orientation}
- H10P 14/22: using physical deposition, e.g. vacuum deposition or sputtering
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/272: {using mask materials other than SiO2 or SiN}
- H10P 14/276: {Lateral overgrowth}
- Y10T 156/10: Methods of surface bonding and/or assembly therefor
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A high-quality, large-area seed crystal for ammonothermal GaN growth and method for fabricating. The seed crystal comprises double-side GaN growth on a large-area substrate. The seed crystal is of relatively low defect density and has flat surfaces free of bowing. The seed crystal is useful for producing large-volume, high-quality bulk GaN crystals by ammonothermal growth methods for eventual wafering into large-area GaN substrates for device fabrication.

## Claims

### Claim 1

A method of fabricating crystalline material comprising:
providing a crystalline substrate having a first surface and a second opposite surface;
forming a first layer of crystalline material containing at least a Group III element and N having a first thickness overlying the first surface of the substrate; and
forming a second layer of crystalline material overlying the second surface of the substrate, the second crystalline material having substantially the same first thickness and having substantially the same composition as the first layer of crystalline material, such that the first crystalline material and second crystalline material are substantially free from bow;
wherein the first layer is formed by a process selected from MOCVD, HVPE, LPE, and MBE; and the second layer is formed by a process selected from MOCVD, HVPE, LPE, and MBE.

### Claim 2 (depends on 1)

The method of claim 1 wherein the structure substantially free from bow is then used as a seed for growth.

### Claim 3 (depends on 1)

The method of claim 1 wherein the first layer of crystalline material and the second layer of crystalline material are formed at the same time.

### Claim 4 (depends on 1)

The method of claim 1 wherein the crystalline substrate comprises two separate crystalline wafers that have been bonded or fused together.

### Claim 5

An epitaxial layer grown on crystalline material wherein the crystalline material is fabricated by a method comprising:
providing a crystalline substrate having a first surface and a second opposite surface;
forming a first layer of crystalline material containing at least a Group III element and N having a first thickness overlying the first surface of the substrate; and
forming a second layer of crystalline material overlying the second surface of the substrate, the second crystalline material having substantially the same first thickness and having substantially the same composition as the first layer of crystalline material, such that the first crystalline material and second crystalline material are substantially free from bow.

### Claim 6 (depends on 1)

The method of claim 1 wherein the first layer of crystalline material or the second layer of crystalline material has an orientation within 10 degrees of (10-10) or (11-20), along with their associated family of planes.

### Claim 7 (depends on 1)

The method of claim 1 wherein the first layer of crystalline material or the second layer of crystalline material has a semipolar orientation.

### Claim 8 (depends on 7)

The method of claim 7 wherein a semipolar orientation refers to a plane with an orientation within 5 degrees of (10-11), (10-1-1), (10-12), (10-1-2), (10-13), (10-1-3), (11-21), (11-2-1), (20-21), (20-2-1),(10-14), (10-1-4), (11-22),or (11-2-2), along with their associated families of planes.

### Claim 9 (depends on 1)

The method of claim 1 wherein the first layer and the second layer are within 500 microns of each other in thickness.

### Claim 10 (depends on 1)

The method of claim 1 further comprising at least one overlying layer covering the first layer deposited on the first layer prior to forming the second layer.

### Claim 11

A method of fabricating crystalline material comprising:
providing a first crystalline substrate material having a first surface and a second surface;
forming a first thickness of first crystalline material overlying the first surface of the first crystalline substrate material, the first thickness of first crystalline material having a first orientation;
providing a second crystalline substrate material having a first surface and a second surface;
forming a second thickness of second crystalline material overlying the first surface of the second crystalline substrate material, the second thickness of second crystalline material having a second orientation; and
attaching the first crystalline substrate and the second crystalline substrate to form a composite substrate such that the composite substrate is configured to be substantially free from bow.

### Claim 12 (depends on 11)

The method of claim 11 wherein the step of attaching is performed by a process selected from wafer fusion, wafer bonding, semiconductor wafer bonding, solder bonding, thermocompression bonding, eutectic bonding, and diffusion bonding.

### Claim 13 (depends on 11)

The method of claim 11 wherein at least one material is disposed between the first crystalline substrate and the second crystalline substrate.

### Claim 14 (depends on 11)

The method of claim 11 wherein the attaching uses at least one material disposed between the first crystalline substrate and the second crystalline substrate.

### Claim 15

A method of fabricating crystalline material containing at least a Group III element and N comprising:
providing a crystalline substrate having a first surface and a second opposite surface;
forming a first layer of crystalline material having a first thickness overlying the first surface of the crystalline substrate; and
forming a second layer of crystalline material overlying the second surface of the crystalline substrate, the second layer of crystalline material having substantially the same first thickness and having substantially the same composition as the first layer of crystalline material overlying the first surface of the crystalline substrate, such that the crystalline substrate together with the first layer of crystalline material and the second layer of crystalline material creates a structure that is substantially free from bow.

### Claim 16 (depends on 15)

The method of claim 15 wherein the first layer of crystalline material and the second layer of crystalline material are formed at the same time.

### Claim 17

A method for fabricating crystalline material comprising:
providing a first crystalline substrate material having a first surface and a second surface;
forming a first thickness of first crystalline material overlying the first surface of the first crystalline substrate material, the first thickness of first crystalline material having a first orientation;
providing a second crystalline substrate material having a first surface and a second surface;
forming a second thickness of second crystalline material overlying the first surface of the second crystalline substrate material, the second thickness of second crystalline material having a second orientation; and
attaching the first crystalline substrate and the second crystalline substrate at their second surfaces, such that the first crystalline material and second crystalline material are substantially free from bow.

### Claim 18 (depends on 17)

The method of claim 17 wherein the attaching is performed by a process selected from wafer fusion, wafer bonding, semiconductor wafer bonding, solder bonding, thermocompression bonding, eutectic bonding, and diffusion bonding.

### Claim 19 (depends on 17)

The method of claim 17 wherein the first orientation of the first crystalline material and the second orientation of the second crystalline material have an orientation within 10 degrees of each other.

### Claim 20 (depends on 17)

The method of claim 17 wherein the first orientation of the first crystalline material and the second orientation of the second crystalline material have an orientation within 170-190 degrees of each other.

### Claim 21 (depends on 17)

The method of claim 17 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material comprise a nonpolar orientation.

### Claim 22 (depends on 17)

The method of claim 17 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material comprise a semipolar orientation.

### Claim 23 (depends on 17)

The method of claim 17 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material have an orientation within 10 degrees of a (0001) or a (000-1) crystallographic orientation.

### Claim 24 (depends on 17)

The method of claim 17 wherein the crystalline substrate contains one or more materials selected from the group consisting of sapphire (Al2O3), silicon carbide (SiC), silicon (Si), spinel (MgAl2O4),LiGaO2, LiAlO2, ZrB2 a Group III-V material, and a Group II-VI material.

### Claim 25 (depends on 17)

The method of claim 17 wherein the first crystalline material and the second crystalline material comprise a wurtzite crystal structure.

### Claim 26

A method for fabricating crystalline material comprising:
providing a crystalline substrate material having a first surface and a second surface;
forming a first crystalline material overlying the first surface of the crystalline substrate material, the first crystalline material having a first lattice constant; and
forming a second crystalline material overlying the second surface of the crystalline substrate material, the second crystalline material having a second lattice constant, such that the lattice constant of the second crystalline material is substantially the same as the lattice constant of the first crystalline material.

### Claim 27 (depends on 26)

The method of claim 26 wherein the crystalline substrate material, the first crystalline material, and the second crystalline material are substantially free from bow.

### Claim 28 (depends on 26)

The method of claim 26 wherein the first crystalline material and the second crystalline material are substantially free from bow.

### Claim 29 (depends on 26)

The method of claim 26 wherein the first crystalline material and the second crystalline material comprise a wurtzite crystal structure.

### Claim 30

A method of fabricating crystalline material comprising:
providing a first crystalline substrate material having a first surface and a second surface;
forming a first thickness of first crystalline material overlying the first surface of the first crystalline substrate material, the first thickness of first crystalline material having a first orientation;
providing a second crystalline substrate material having a first surface and a second surface;
forming a second thickness of second crystalline material overlying the first surface of the second crystalline substrate material, the second thickness of second crystalline material having a second orientation; and
forming a composite structure containing the first crystalline substrate material, the first crystalline material, the second crystalline substrate material, and the second crystalline material such that the surface of the first crystalline material is disposed opposite the surface of the second crystalline material.

### Claim 31 (depends on 30)

The method of claim 30 wherein the composite structure is configured to be substantially free from bow.

### Claim 32 (depends on 30)

The method of claim 30 wherein a material is disposed between the first crystalline substrate material and the second crystalline substrate material.

### Claim 33 (depends on 30)

The method of claim 30 wherein the first orientation of the first crystalline material and the second orientation of the second crystalline material have an orientation within 10 degrees of each other.

### Claim 34 (depends on 30)

The method of claim 30 wherein the first orientation of the first crystalline material and the second orientation of the second crystalline material have an orientation within 170-190 degrees of each other.

### Claim 35 (depends on 30)

The method of claim 30 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material comprise a nonpolar orientation.

### Claim 36 (depends on 30)

The method of claim 30 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material comprise a semipolar orientation.

### Claim 37 (depends on 30)

The method of claim 30 wherein the first orientation of the first crystalline material or the second orientation of the second crystalline material have an orientation within 10 degrees of (0001) or (000-1) crystallographic orientations.

### Claim 38

A method of fabricating crystalline material comprising:
providing a first crystalline substrate material having a first surface and a second surface;
forming a first thickness of first crystalline material overlying the first surface of the first crystalline substrate material, the first crystalline material having a first lattice constant;
providing a second crystalline substrate material having a first surface and a second surface;
forming a second thickness of second crystalline material overlying the first surface of the second crystalline substrate material, the second crystalline material having a second lattice constant, such that the lattice constant of the second crystalline material is substantially the same as the lattice constant of the first crystalline material; and
forming a composite structure containing the first crystalline substrate material, the first crystalline material, the second crystalline substrate material, and the second crystalline material such that the surface of the first crystalline material is disposed opposite the surface of the second crystalline material.

### Claim 39 (depends on 38)

The method of claim 38 wherein the composite structure is configured to be substantially free from bow.

### Claim 40 (depends on 38)

The method of claim 38 wherein a material is disposed between the first crystalline substrate material and the second crystalline substrate material.

### Claim 41 (depends on 38)

The method of claim 38 wherein the first crystalline material and the second crystalline material comprise a wurtzite crystal structure.

### Claim 42

A method of fabricating crystalline material comprising:
providing a first crystalline substrate material having a first surface and a second surface;
forming a first thickness of first crystalline material overlying the first surface of the first crystalline substrate material, the first crystalline material having a first coefficient of thermal expansion;
providing a second crystalline substrate material having a first surface and a second surface;
forming a second thickness of second crystalline material overlying the first surface of the second crystalline substrate material, the second crystalline material having a second coefficient of thermal expansion, such that the coefficient of thermal expansion of the second crystalline material is substantially the same as the coefficient of thermal expansion of the first crystalline material; and
forming a composite structure containing the first crystalline substrate material, the first crystalline material, the second crystalline substrate material, and the second crystalline material such that the surface of the first crystalline material is disposed opposite the surface of the second crystalline material.

### Claim 43 (depends on 42)

The method of claim 42 wherein the composite structure is configured to be substantially free from bow.

### Claim 44 (depends on 43)

The method of claim 43 wherein the composite structure is configured so the first crystalline material or the second crystalline material is substantially free from bow.

### Claim 45 (depends on 43)

The method of claim 43 wherein a material is disposed between the first crystalline substrate material and the second crystalline substrate material.