Method and apparatus for single crystal gallium nitride (GaN) bulk synthesis

• US 6,372,041 B1
• Filed: 01/07/2000
• Issued: 04/16/2002
• Est. Priority Date: 01/08/1999
• Status: Expired due to Term

• Current Assignee: Dow, Inc.
• Original Assignee: GAN Semiconductor, Inc. (Dow, Inc.)
• Inventors: Cho, Hak Dong, Kang, Sang Kyu
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US09/478,954
• Time in Patent Office: 830 Days
• Field of Search: 117/84, 117/85, 117/94, 117/95, 117/105, 117/108
• US Class Current: 117/84
• CPC Class Codes: C30B 25/00 Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 29/60 characterised by shape
• CPC Class Codes: C30B 29/64 Flat crystals, e.g. plates, strips or discs
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 33/0075 comprising nitride compounds

Abstract

A method and apparatus for homoepitaxial growth of freestanding, single bulk crystal Gallium Nitride (GaN) are provided, wherein a step of nucleating GaN in a reactor results in a GaN nucleation layer having a thickness of a few monolayers. The nucleation layer is stabilized, and a single bulk crystal GaN is grown from gas phase reactants on the GaN nucleation layer. The reactor is formed from ultra low oxygen stainless steel.

Claims

1. A method for growing a single freestanding Gallium Nitride (GaN) crystal, comprising:

generating a GaN substrate structure by growing a GaN nucleation layer on a susceptor, wherein a thickness of the nucleation layer is at least one monolayer;

stabilizing the GaN substrate structure; and

growing a GaN layer on at least one surface of the GaN substrate structure using a plurality of gas phase reactants.

2. The method of claim 1, further comprising:

providing a reactor chamber formed from ultra low oxygen stainless steel;

cleaning the susceptor;

setting the susceptor in the reactor chamber;

rotating at least one of the reactor chamber and at least one heating element; and

initializing and stabilizing an environment of the reactor chamber.

3. The method of claim 2, wherein generation of the GaN substrate structure is performed when the environment of the reactor chamber is stabilized and controlled within a first set of environmental parameters.

4. The method of claim 3, wherein the first set of environmental parameters includes a pressure selected from a range of 10⁻

3 Torr and 10<sup>−

6</sup> Torr and a temperature selected from a range of 300 degrees Celsius and 800 degrees Celsius, wherein the selected temperature is maintained within plus or minus 1 degree Celsius.

5. The method of claim 2, wherein growth of the GaN layer is performed when the environment of the reactor chamber is stabilized and controlled within a second set of environmental parameters.

6. The method of claim 5, wherein the second set of environmental parameters includes a pressure selected from a range of 10⁻

3 Torr and atmosphere and a temperature selected from a range of 450 degrees Celsius and 1250 degrees Celsius, wherein the selected temperature is maintained within plus or minus 2 degrees Celsius.

7. The method of claim 2, wherein stabilizing the GaN substrate structure comprises changing the environment of the reactor chamber from a first set of environmental parameters to a second set of environmental parameters.

8. The method of claim 1, wherein the plurality of gas phase reactants comprise gases selected from a group consisting of Nitrogen, Hydrogen, Ammonia, Gallium, Aluminum, and Indium.

9. The method of claim 1, wherein growth of the GaN nucleation layer comprises exposing a Pyro-Boron-Nitride (PBN) susceptor to a first gas mixture comprising hydrogen gas, nitrogen gas, ammonia gas, and a second gas mixture comprising at least one group III-V metal alloy.

10. The method of claim 9, wherein the PBN susceptor has a thickness of approximately 4 millimeters and a diameter of approximately 5 inches, wherein the PBN susceptor holds 3 GaN semiconductor wafers.

11. The method of claim 1, wherein the nucleation layer comprises 5 to 30 monolayers, wherein the nucleation layer has a thickness dimension approximately in a range of 10 to 70 Angstroms.

12. The method of claim 1, wherein the GaN layer is grown at a rate between 20 and 100 micrometers per hour, wherein the lattice structure is wurtzite.