Thermal etching of 6H-SiC substrate surface

Thermal etching was investigated as one of the methods of obtaining atomically flat surfaces of SiC substrates. The formation of a graphite layer on substrate surface was suppressed by reducing the C/Si ratio in the vapor phase. Although (11 (2) over bar0) substrates etched in argon atmosphere had round pits on their surface, such pits were not observed and an atomically flat surface with an RMS roughness of approximately 0.3 nm was obtained in nitrogen atmosphere even at the high etching rate of 250 mum/h. The substrates with higher nitrogen concentrations had both higher surface flatness and higher etching rate. The thermal etching method was found to be an effective technique for obtaining the flat surface of SiC substrates that is suitable for crystal growth and/or device fabrication. The etching mechanisms of (0001) and (11 (2) over bar0) surfaces were compared, and the result was discussed by taking into consideration the bond configuration on the surface.