Method for growth of a merged crystal by bonding at least a first and second crystal to an adhesion layer to form a tiled substrate and growing a crystalline composition over said tiled substrate

• US 10,400,352 B2
• Filed: 02/07/2017
• Issued: 09/03/2019
• Est. Priority Date: 06/18/2010
• Status: Active Grant

• Current Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: D'Evelyn, Mark P., Speck, James S., Kamber, Derrick S., Pocius, Douglas W.
• Primary Examiner(s): Bratland, Jr., Kenneth A
• Application Number:
  US15/426,770
• Publication Number:
  US 20170145585A1
• Time in Patent Office: 938 Days
• Field of Search: 117 84, 117 88, 117 94, 117 99-101, 117106, 117109, 117937, 117952, 438455, 438459, 438503-504, 438766, 438795, 438798
• CPC Class Codes: C30B 19/068 Substrate holders
• CPC Class Codes: C30B 19/12 characterised by the substrate
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 33/06 Joining of crystals
• CPC Class Codes: C30B 7/105 using ammonia as solvent, i.e. ammonothermal processes
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 29/2003 Nitride compounds

Abstract

Techniques for processing materials in supercritical fluids including processing in a capsule disposed within a high-pressure apparatus enclosure are disclosed. The disclosed techniques are useful for growing crystals of GaN, AlN, InN, and their alloys, including InGaN, AlGaN, and AlInGaN for the manufacture of bulk or patterned substrates, which in turn can be used to make optoelectronic devices, lasers, light emitting diodes, solar cells, photoelectrochemical water splitting and hydrogen generation devices, photodetectors, integrated circuits, and transistors.

Claims

1. A method for growth of a large-area merged crystal, the method comprising:

depositing an adhesion layer on a surface of a handle substrate, said adhesion layer having a melting point at a first temperature;

bonding at least a first crystal and a second crystal to said adhesion layer to form a tiled substrate while said adhesion layer is at a temperature of no less than said first temperature, to melt said adhesion layer to enhance its adhesion;

heat treating said adhesion layer to form a heat-treated adhesion layer, said heat-treated adhesion layer having a melting point at a second temperature higher than said first temperature; and

laterally and vertically growing a crystalline, composition over said tiled substrate at a third temperature to form a merged crystal, said third temperature being higher than said first temperature and below said second temperature.

2. The method of claim 1 wherein the first crystal and the second crystal comprise GaN.

3. The method of claim 1 wherein the average dislocation density of each of the first crystal and the second crystal is below 10⁷ cm⁻

2.

4. The method of claim 1 wherein the handle substrate is selected from among selected from sapphire, aluminum oxide, mullite, silicon, silicon nitride, germanium, silicon germanium, diamond, gallium arsenide, silicon carbide, MgAl₂O₄ spinel, zinc oxide, indium phosphide, gallium nitride, indium nitride, gallium aluminum indium nitride, and aluminum nitride.

5. The method of claim 1 wherein the handle substrate has a thermal expansion coefficient parallel to its surface between room temperature and 700 degrees Celsius that is between 5.5×

10<sup>−

6</sup> K<sup>−

1</sup> and 6.5×

10<sup>−

6</sup> K<sup>−

1</sup>.

6. The method of claim 1 wherein the handle substrate has the same composition as the first and second crystals.

7. The method of claim 1, wherein the at least two crystals are placed on the handle substrate by means of a pick and place machine, a robot, or a die attach tool.

8. The method of claim 1 wherein said first crystal having a first nominal crystallographic orientation (x₁ y₁ z₁), and said second crystal having a second nominal crystallographic orientation (x₂ y₂ z₂), said first nominal crystallographic orientation (x₁ y₁ z₁) and said second nominal crystallographic orientation (x₂ y₂ z₂) being identical

wherein said first and second crystals define first and second domains in said merged crystal;

wherein;

z₁ is a negative surface normal of the first nominal crystallographic orientation, and x₁ and y₁ are crystallographic vectors that are orthogonal to z₁;

z₂ is a negative surface normal of the second nominal crystallographic orientation, and x₂ and y₂ are crystallographic vectors that are orthogonal to z₂;

a polar misorientation angle γ

between z₁ and z₂ is greater than 0.005 degrees and less than 0.5 degrees;

a misorientation angle α

between x₁ and x₂ is greater than 0.01 degrees and less than 1 degree; and

a misorientation angle β

between y₁ and y₂ is greater than 0.01 degrees and less than 1 degree.

9. The method of claim 1, wherein said first temperature is no greater than 500°

C., said second temperature is no less than 700°

C., and said third temperature is no less than 600°

C.

10. The method of claim 1, wherein said first crystal comprises at least one of an ion implanted region and a release layer;

and further comprising;

separating the first crystal at the ion implanted region or release layer into a first region that remains bonded to the handle substrate and a second region that, is removed from the first region;

bonding said second crystal to said adhesion layer proximate to said first region of said first crystal, said second crystal comprising at least one of an ion implanted region and a release layer;

separating the second crystal at the ion implanted region or release layer into a first region that remains bonded to the handle substrate and a second region that is removed from the first region to form a tiled substrate.

11. The method of claim 10 wherein the second crystal comprises the second region of the first crystal.

12. The method of claim 1, wherein said merged crystal is utilized as a seed crystal for bulk crystal growth.

13. The method of claim 8 wherein the first domain and the second domain are separated by a line of dislocations with a linear density less than 2×

10⁵ cm<sup>−

1</sup> and the polar misorientation angle γ

between the first domain and the second domain is less than 0.3 degree and the misorientation angles α and

β

are less than 0.6 degree.

14. The method of claim 1, wherein laterally and vertically growing a crystalline composition over said tiled substrate at a second temperature to form a merged crystal is performed using ammonothermal growth.

15. The method of claim 1 wherein said heat treating is after said first and second crystals are adhered to said adhesion layer.

16. The method of claim 1 wherein the first crystal and the second crystal comprise GaN.

17. The method of claim 10, further comprising:

separating the merged crystal from the handle substrate.

18. The method of claim 1 wherein the adhesion layer comprises at least one of SiO₂, GeO₂, SiN_x, AlN_x, B, Al, Si, P, Zn, Ga, Ge, Au, Ni, Ti, Cr, Cd, In, Sn, Sb, Tl, or Pb, or an oxide, nitride, or oxynitride thereof.