Method for smoothing surface of a substrate containing gallium and nitrogen
First Claim
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1. A method for smoothing a substrate for epitaxial growth, said substrate comprising at least a gallium and nitrogen containing material, and having a top surface, at least a portion of said top surface having a first RMS roughness, the method comprising:
- heat treating said substrate to form an annealed substrate surface; and
wherein said heat treating comprises at least a first step and a second step, in said first step, subjecting said substrate to a first temperature of at least about 1000°
C. for a first time period of about 5 minutes to about 30 minutes in the presence of H2 and NH3, and, in said second step, after said first step, subjecting the substrate to a second temperature, substantially higher than said first temperature for a second time period in the presence of at least NH3 to form said annealed substrate surface wherein, after said first step, said at least a portion of said top surface comprises a first surface smoothness, and after said second step, said at least a portion of said top surface comprises a second surface smoothness different than said first surface smoothness and defined by a second RMS roughness less than said first RMS roughness, andwherein said heat treating occurs prior to epitaxial growth.
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Abstract
Disclosed is a method for processing GaN based substrate material for manufacturing light-emitting diodes, lasers, and other types of devices. In various embodiments, a GaN substrate is exposed to nitrogen and hydrogen at a high temperature. This process causes the surface of the GaN substrate to anneal and become smooth. Then other processes, such as growing epitaxial layers over the surface of GaN substrate, can be performed over the smooth surface of the GaN substrate.
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26 Claims
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1. A method for smoothing a substrate for epitaxial growth, said substrate comprising at least a gallium and nitrogen containing material, and having a top surface, at least a portion of said top surface having a first RMS roughness, the method comprising:
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heat treating said substrate to form an annealed substrate surface; and
wherein said heat treating comprises at least a first step and a second step, in said first step, subjecting said substrate to a first temperature of at least about 1000°
C. for a first time period of about 5 minutes to about 30 minutes in the presence of H2 and NH3, and, in said second step, after said first step, subjecting the substrate to a second temperature, substantially higher than said first temperature for a second time period in the presence of at least NH3 to form said annealed substrate surface wherein, after said first step, said at least a portion of said top surface comprises a first surface smoothness, and after said second step, said at least a portion of said top surface comprises a second surface smoothness different than said first surface smoothness and defined by a second RMS roughness less than said first RMS roughness, andwherein said heat treating occurs prior to epitaxial growth. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification