Methods of growing a silicon carbide epitaxial layer on a substrate to increase and control carrier lifetime
A method of growing an epitaxial layer on a substrate is generally provided. According to the method, the substrate is heated in a chemical vapor deposition chamber to a growth temperature in the presence of a carbon source gas, then the epitaxial layer is grown on the substrate at the growth temperature, and finally the substrate is cooled in a chemical vapor deposition chamber to at least about 80% of the growth temperature in the presence of a carbon source gas. Substrates formed from this method can have a carrier lifetime between about 0.25 μs and about 9.9 μs.
1. A method of growing a silicon carbide epitaxial layer on a substrate, the method comprising
heating the substrate in a temperature increase atmosphere from about 1000° C. to a growth temperature that is between about 1400° C. and about 1650° C., wherein the temperature increase atmosphere comprises a first carbon source gas;
growing the silicon carbide epitaxial layer on the substrate at the growth temperature in a growth atmosphere, wherein the growth atmosphere comprises a silane source gas; and
after termination of epilayer growth, cooling the substrate in a temperature decrease atmosphere until the temperature reaches about 1000° C. or lower, wherein the temperature decrease atmosphere comprises a second carbon source gas, wherein the temperature decrease atmosphere is substantially free of silane source gas.
2. The method of claim 1 , wherein the temperature increase atmosphere comprises the first carbon source gas and a carrier gas.
3. The method of claim 2 , wherein the carrier gas comprises hydrogen, argon, helium, nitrogen, or a mixture thereof.
4. The method of claim 2 , wherein the temperature increase atmosphere is substantially free from a silane source.
5. The method of claim 1 , wherein the temperature increase atmosphere consists essentially of the first carbon source gas and a carrier gas.
6. The method of claim 1 , wherein the temperature decrease atmosphere comprises the second carbon source gas and a carrier gas.
7. The method of claim 1 , wherein the temperature decrease atmosphere consists essentially of the second carbon source gas and a carrier gas.
8. The method of claim 1 , wherein heating the substrate, growing the epitaxial layer on the substrate, and cooling the substrate are performed in a chemical vapor deposition chamber.
9. The method of claim 8 , wherein the chemical vapor deposition chamber has a pressure of from about 200 Torr to about 400 Torr through heating, growing, and cooling.
10. The method of claim 8 , wherein a susceptor is utilized to heat the substrate within the chemical vapor deposition chamber.
11. The method of claim 10 , wherein the susceptor is a graphite susceptor having a tantalum carbide coating.
12. The method of claim 1 , wherein the growth atmosphere further comprises a third carbon source gas.
13. The method of claim 12 , wherein the first carbon source gas, the second carbon source gas, and the third carbon source gas comprise propane.
14. The method of claim 12 , wherein a ratio of the third carbon source gas to the silane source gas present in the growth atmosphere is about 0.1 to about 10 by gas flow rate.
15. The method of claim 1 , wherein the silane source gas comprises dichiorosilane.