Smoothing method for semiconductor material and wafers produced by same
View Patent ↗A smoothing method for semiconductor material and semiconductor wafers produced by the method are disclosed. Semiconductor wafers with reduced atomic steps, as well with reduced scratches and subsurface defects can be produced. Such wafers feature an improved growth surface that can provide for the growth of an epilayer with reduced macroscopic defects and defect densities. A method of smoothing the surface of a wafer according to example embodiments of the invention includes planarizing the surface of a semiconductor wafer, and then oxidizing the wafer to achieve a specified thickness of oxide on the surface of the wafer. The oxide can then be stripped from the surface of the semiconductor wafer.
1. A method of processing a semiconductor wafer, the method comprising:
chemically mechanically planarizing a surface of the semiconductor wafer; and
oxidizing the semiconductor wafer to form an oxide having a thickness of at least 500 angstroms to reduce atomic steps caused by crystal lattice planes, and at least one of scratches and subsurface damage.
2. The method of claim 1 further comprising stripping from the semiconductor wafer the oxide formed by the oxidizing of the semiconductor wafer.
3. The method of claim 2 wherein the semiconductor wafer further comprises silicon carbide.
4. The method of claim 3 wherein the oxidizing of the semiconductor wafer further comprises thermally oxidizing the wafer at a temperature of between 1225° C. and 1800° C.
5. A method of processing a semiconductor wafer, the method comprising:
chemically mechanically planarizing a surface of the semiconductor wafer; and
thermally dry oxidizing the semiconductor wafer to form an oxide having a thickness of at least 500 angstroms to reduce atomic steps caused by crystal lattice planes, and at least one of scratches and subsurface damage.
6. The method of claim 5 further comprising stripping from the semiconductor wafer the oxide formed by the oxidizing of the semiconductor wafer.
7. The method of claim 6 wherein the semiconductor wafer further comprises silicon carbide.
8. The method of claim 5 wherein the thermally oxidizing of the semiconductor wafer further comprises holding the wafer at a temperature of between 1225° C. and 1800° C.
9. A method of processing a semiconductor wafer, the method comprising:
chemically mechanically planarizing a surface of the semiconductor wafer; and
reducing atomic steps caused by crystal lattice planes, and at least one of scratches and subsurface damage, using an oxide formed by dry oxidation.
10. The method of claim 9 wherein the semiconductor wafer is made of silicon carbide.
11. The method of claim 10 wherein an appearance of atomic steps on the surface is reduced by at least 50% as compared to the appearance of atomic steps immediately after the planarizing.
12. The method of claim 11 wherein the oxide has a specified thickness.
13. The method of claim 12 wherein the specified thickness is at least 500 angstroms.
14. The method of claim 13 wherein the appearance of atomic steps is reduced by at least 75%.
15. The method of claim 13 wherein the subsurface damage is reduced so that a subsurface defect density is numerically no greater than a defect density in the bulk crystal from which the semiconductor wafer was cut or the center of the semiconductor wafer.