REACTIVE ION ETCHING OF SIC THIN-FILMS USING FLUORINATED GASES

Reactive ion etching (RIE) using fluorinated gases, such as admixtures of CF//4 with O//2, has been conducted on sputter deposited films of SiC. For comparison purposes, the same experiments with SiO//2 films and Si wafers have been conducted. The influence of rf power, pressure, and O//2 concentration on etch rate in CF//4 plus O//2, SF//6 plus He, and Ar gases has been investigated. RIE mechanisms were studied using in situ monitoring of excited fluorine emission intensity and dc self-bias at the lower electrode. In both CF//4 plus 4 per-cent O//2 and SF//6 plus 50 per-cent He, the etch rates of Si, SiO//2, and SiC all increase monotonically with the rf power. The results are presented and discussed. Among other things, they suggest that a certain etching inhibitor layer exists on the surface of SiC, which can weakly react with the O//2 plasma. Auger electron spectroscopy data indicate that this layer consists of carbon atoms.