Thermal absorption coating on sapphire for epitaxial process
OwnerSang H. Choi, Adam J. Duzikinventors
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Abstract
A method of forming an epitaxial layer on a substrate such as a sapphire wafer that does not readily absorb thermal radiation. The method includes coating a first side surface of the substrate with an energy-absorbing opaque material. The opaque material forms a thermally absorptive coating on the substrate. The coated substrate may be heated to remove contaminants from the thermally absorptive coating. The coated substrate is positioned in a vacuum deposition chamber and heated by directing radiative energy onto the thermally absorptive coating. An epitaxial layer such as GaN or SiGe is formed on a second side surface of the substrate opposite the thermally absorptive coating.
Claims20
A method of forming an epitaxial layer on a sapphire substrate having first and second opposite side surfaces, the method comprising:
- coating the first opposite side surface of the sapphire substrate with an energy-absorbing opaque paint that is stable at high temperatures to form a thermally absorptive coating on the first side of the sapphire substrate;
- incrementally heating the coated sapphire substrate to remove contaminants originated from the thermally absorptive coating, wherein incrementally heating the coated sapphire substrate comprises baking the coated sapphire substrate at a first temperature below about 650° C. for a first time period, followed by baking the coated sapphire substrate at a second temperature above the first temperature and below 650° C. for a second time period, followed by baking the coated sapphire substrate at about 650° C. for a third time period and wherein the first time period, the second time period, and the third time period are each at least about 15 minutes;
- cooling the coated sapphire substrate;
- positioning the coated sapphire substrate in a vacuum deposition chamber;
- heating the coated sapphire substrate in the vacuum deposition chamber by directing radiative energy onto the thermally absorptive coating on the first side of the sapphire substrate;
- forming an epitaxial layer on the second side of the coated sapphire substrate opposite the thermally absorptive coating.
A method of forming an epitaxial layer on a sapphire substrate having first and second opposite side surfaces, the method comprising:
- coating the first opposite side surface of the sapphire substrate with an energy-absorbing opaque paint that is stable at high temperatures to form a thermally absorptive coating on the first side of the sapphire substrate;
- incrementally heating the coated sapphire substrate to remove contaminants originated from the thermally absorptive coating;
- cooling the coated sapphire substrate;
- positioning the coated sapphire substrate in a vacuum deposition chamber;
- heating the coated sapphire substrate in the vacuum deposition chamber by directing radiative energy onto the thermally absorptive coating on the first side of the sapphire substrate;
- and
- forming an epitaxial layer on the second side of the coated sapphire substrate opposite the thermally absorptive coating,
- wherein:
- incrementally heating the coated sapphire substrate comprises heating the coated sapphire substrate to about 650° C.;
- the coated sapphire substrate is a wafer;
- and
- the coated sapphire substrate is baked at about 400° C. for about 15 minutes, followed by baking at about 500° C. for about 15 minutes, followed by baking at about 650° C. for at least about 20 minutes.
A method of forming an epitaxial layer on a substrate having first and second opposite side surfaces, the method comprising:
- coating at least a portion of the first opposite side surface of the substrate with an energy-absorbing opaque paint that is stable at high temperatures to form a thermally absorptive coating on the first side of the substrate resulting in a coated substrate;
- heating the coated substrate to remove contaminants from the thermally absorptive coating by baking the coated sapphire substrate at a first temperature less than about 650° C., then baking the coated sapphire substrate at a second temperature above the first temperature and below about 650° C. for a second time period, followed by baking the coated sapphire substrate at about 650° C. for a third time period, wherein the first time period, the second time period, and the third time period are each at least about 15 minutes;
- positioning the coated substrate in a vacuum deposition chamber;
- heating the coated substrate in the vacuum deposition chamber by directing radiative energy onto the thermally absorptive coating;
- forming an epitaxial layer on the second side of the coated substrate opposite the thermally absorptive coating;
- and
- removing the thermally absorptive coating.
Dependencies are inferred from the claim text.