Properties of thermally etched 4H-SiC by chlorine-oxygen system

By the use of Cl-2-O-2 thermal etching method, the etching rates of 4H-SiC were reached to about 1 mu m/h for Si and 40 mu m/h for C face at 950 degrees C. Etch pits only appeared over 0.25-mu m-etched depth on the 4H-SiC (0001) Si face. The shapes and density of etch pits are similar tendencies in the case of molten KOH etched surface. To study the relationship between thermally etched surface features and crystal defects, the planar mapping electron-beam-induced current (EBIC) technique was carried out. Almost dark areas in the EBIC image correspond to the etch pits. From the EBIC image, a shell-like pit formed by the Cl-2-O-2 etching on the (0001) Si face is a basal plane dislocation.