単結晶SiC基板の高能率鏡面仕上げ技術に関する研究 : —定圧研削および紫外光支援研磨による鏡面仕上げ加工—

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SiC is a promising next-generation semiconductor material for high-temperature, high-frequency and high-power device applications due to its excellent properties, such as good thermal conductivity, good carrier mobility and high chemical stability. In device fabrication, atomically smooth and damage-free SiC substrates are highly required for producing high-quality epitaxial films and gate-oxide interfaces. However, such SiC substrates are relatively difficult to machine because of its mechanical hardness and marked chemical inertness. We have proposed and developed an ultra-precision polishing method for single crystal SiC substrates utilizing an ultraviolet (UV) irradiation. This paper describes the planarization method of SiC substrate by constant-pressure grinding and ultraviolet irradiation assisted polishing. The surface qualities were measured and evaluated using phase-shift interferometric microscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The obtained results show that the many asperities on the preprocessed surface could be completely removed and the surface roughness was markedly improved by constant-pressure grinding and ultraviolet irradiation assisted polishing. The microroughness of the processed surface was improved and realized to be 0.12 nm (Ra) and 1.55 nm (Rz), respectively.