Smoothing method for semiconductor material and wafers produced by same
AssigneeCree, Inc.
InventorsDavis Andrew McClure, Nathaniel Mark Williams
Life of this patent
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Abstract
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.
Claims13
A wafer comprising:
- a substrate with a surface wherein an appearance of atomic steps is reduced by at least 50% compared to the surface after chemical mechanical planarization and an arithmetic mean surface roughness less than 0.2 nm over a 1×1 micron or greater area of the surface;
- and
- an epitaxial layer on the substrate, wherein the epitaxial layer is free of defects from 10 to 5000 microns in size that are characterized by localized morphological changes, and has a defect density of less than 5×107 cm−2.
A semiconductor wafer comprising a substrate with a surface wherein an appearance of atomic steps is reduced by at least 50% compared to the surface after mechanical material removal and chemical mechanical planarization, the surface also having an arithmetic mean surface roughness less than 0.2 nm over a 1×1 micron or greater area and the semiconductor wafer also having an epitaxial layer with a defect density of less than 5×107 cm−2, and being prepared by a process comprising:
- planarizing a surface of the semiconductor wafer;
- oxidizing the semiconductor wafer;
- and
- growing the epitaxial layer on the substrate so as to be free of defects from 10 to 5000 microns in size that are characterized by localized morphological changes.
Dependencies are inferred from the claim text.