| 摘要 |
PROBLEM TO BE SOLVED: To provide a sapphire substrate capable of eliminating the problem that abnormal growth and substrate crack are increased upon epitaxial growth, although the surface flatness of the growing layer is improved when the sapphire substrate is used with chamfering processing at edges thereof. SOLUTION: The epitaxial growth sapphire substrate is subjected to mirror surface processing at least on one surface and to edge processing for both edges composed of the surface and end surfaces. In the sapphire substrate, the edge processing is tapering processing and a tapered surface formed by the tapering processing is the slope of the angle of 20 to 70°formed with respect to the sapphire substrate surface, and average surface roughness Ra of the tapered surface and the end surfaces is≤0.05μm. Alternatively, the edge processing is R processing where R is 0.5t to t when the thickness t of the sapphire substrate is assumed to be t, and the average surface roughness Ra of the surface of the R process is≤0.05μm. COPYRIGHT: (C)2006,JPO&NCIPI
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