The authors investigated the effects of various additive gases and different injection methods on the chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F-2 remote plasmas. N-2 and N-2+O-2 gases in the F-2/Ar/N-2 and F-2/Ar/N-2/O-2 remote plasmas effectively increased the etch rate of the layers. The addition of direct-injected NO gas increased the etch rates most significantly. NO radicals generated by the addition of N-2 and N-2+O-2 or direct-injected NO molecules contributed to the effective removal of nitrogen and oxygen in the silicon nitride and oxide layers, by forming N2O and NO2 by-products, respectively, and thereby enhancing SiF4 formation. As a result of the effective removal of the oxygen, nitrogen, and silicon atoms in the layers, the chemical dry etch rates were enhanced significantly. The process regime for the etch rate enhancement of the layers was extended. at elevated temperature. (c) 2007 American Vacuum Society.