REACTIVE ION ETCHING OF (111) BETA-SIC EPITAXIAL LAYERS ON (111) TIC SUBSTRATES IN CF4+O2+AR

The rate, anisotropy, and morphology obtained by reactive ion etching (RIE) of (111) beta-SiC epilayer surfaces in CF4 + O2 + Ar were determined as functions of O2-to-CF4 ratio and RF incident power density, at 60 mTorr. The beta-SiC etch rate increased from 100 angstrom/min at O2/CF4 = 0, to 380 angstrom/min at O2/CF4 = 1, and then decreased to 0 angstrom/min at O2/(O2 + CF4) = 1. Anisotropic etching was obtained at all O2/CF4 ratios. As-etched surfaces were textured (but flat), C-rich, and contained visible residues adjacent to mesa sidewalls only. The RIE dependence on O2/CF4 ratios and the nearly linear proportional increase of etch rate and \V(dc)\ indicates etching occurred by a combination of chemical reactions of (111) beta-SiC surfaces with F and oxygen radicals and ion bombardment. Titanium carbide (111) surfaces, etched under the same conditions, were isotropically etched, exhibited wavelike morphology, and were free of visible residue.