Anisotropic Etching of SiC in the Mixed Gas of Chlorine and Oxygen

Anisotropic thermal etching of 4H-SiC {0001} and {11-20} substrates was studied in the mixed gas of chlorine (Cl2) and oxygen (O2) over 900oC. Etch pits appeared only on the (0001) Si face. Etching rates depended on the temperature, O2/Cl2 ratio, and an etching direction on the substrate surfaces. When the mesa structure was formed by the selective etching method, sloped sidewalls were observed around the periphery of the mesa. The angle of sidewalls depended on the orientation of substrates.