Surface Preparation of 6H-Silicon Carbide Substrates for Growth of High-Quality SiC Epilayers

摘要

Various surface scratches and defects were eliminated from as-received on-axis 6H-SiC wafers using chemical mechanical polishing (CMP) and It etching techniques. The polished surface was observed from the SiC substrates treated with H_2 etching at 1500℃ for 10 min and the formation of nanosteps was uniformly observed across the fattened surface. To investigate the effect of the surface state of the substrates on the crystal quality of epitaxially grown SiC films, the homoepitaxial growth of 6H-SiC epilayers was carried out on the H_2 etched 6H-SiC substrate using a step controlled method at 1650℃ for 3 hr. The surface morphology and crystal quality of the surface treated 6H-SiC substrates and 6H-SiC epilayers grown on the treated substrates were characterized using AFM and TEM measurements. It was found that the high-quality homoepitaxial 6H-SiC film could be grown on flattened substrate surface with microsteps.