Plasma etching of crystalline and hydrogenated amorphous silicon has been studied in CClF3 gas as a function of pressure and power using a 30 kHz parallel plate plasma-etching system. In contrast to CF4 plasma, etching of amorphous silicon in CClF3 is found to be slower than that of crystalline silicon. The selectivity of crystalline silicon over amorphous silicon is observed in the range 1.5–4.0 in CClF3 plasma as against 0.5–1.0 in CF4 plasma. The effect of mixing oxygen and hydrogen with CClF3 is also discussed. Auger electron spectroscopy has been performed in order to identify the residual chemisorbed species on the sample surface during etching in CClF3 plasma.