Surface Characteristics of Monocrystalline ß-SiC dry etched in fluorinated gases

ABSTRACTMonocrystalline ß-SiC (100) thin films were dry etched in CF4 and NF3 by reactive ion etching (RIE) and in SF6 by plasma etching. The etched surfaces were characterized by Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). The use of a stainless steel or an anodized Al cathode during RIE created a roughened SiC surface, which was contaminated with Fe or Al2 O3respectively. The roughness was caused by a micromasking effect produced by the deposition of these contaminants. By contrast, a carbon cathode yielded a very smooth and a much cleaner etched surface. Plasma etching of SiC in SF6 resulted in a very rough surface, but the AES spectra indicated almost no contamination and very little native oxide or fluorine. The optimal condition for etching SiC was determined to be RIE in NF 3 on a C cathode.