Ultraviolet-excitation Polishing using Photocatalyst and Cathilon: Availability Study for 4H-SiC Wafer Polishing and XAFS Analysis of Chemical State

The availability of ultraviolet-excitation polishing for 4H-SiC wafer and the chemical state of the 4H-SiC surface polished using photocatalyst and cathilon were investigated in absence and presence of an ultraviolet (UV). X-ray absorption fine structure (XAFS) spectroscopy conducted the qualitative analysis of the polished 4H-SiC surface. This analysis was used to clarify the oxides that are formed/removed by decomposition of cathilon dye and water during the polishing of 4H-SiC using TiO2 slurry, cathilon slurry and TiO2-cathilon slurry (mixed slurry), all of which included diamond particles. In polishing the previously sandblasted and handlapped 4H-SiC, TiO2 slurry provides large polishing efficiency and large polished surface roughness, and cathilon slurry provides small polishing efficiency and small polished surface roughness under UV irradiation. The large polishing efficiency, small polished surface roughness and large roughness decrease rate were attained using mixed slurry that is suitable to polish 4H-SiC under UV irradiation. The differences of XAFS spectrum are observed in UV absence/presence among three kinds of slurries. The XAFS analysis mainly investigates and indicates that some oxides form on the surface polished using cathilon and mixed slurries in UV absence/presence. Polishing using mixed slurry provides less volumes of oxides inside SiC on the polished surface, particularly.