Optical emission spectroscopy (OES) and laser interferometry (LI) were investigated as monitoring methods during reactive ion etching (RIE) of hexagonal SiC in SF6/Ar gas mixtures. The etch rate and the surface roughness were monitored by LI, while at the same time OES monitored the intensity of the fluorine-related 704 nm line. It was found that the etch rate is directly related to the above intensity and not to the self-induced DC-bias. This explains the very high etch rates obtained at high pressures (150-250 mTorr) despite the low DC-bias values (similar to100 V). Etch rates higher than 400 nm/min were achieved for 400 W of rf power. (C) 2002 Elsevier Science Ltd. All rights reserved.