Spatial profiles of CF2 concentration in C2 F6 rf plasma are measured by the laser‐induced fluorescence method. The observed profiles are explained by the generation and recombination reaction mechanisms of CF2 . It is found that the deposition rate of fluorocarbon polymer on SiO2 film is proportional to [CF2]n ; n=2.5–3.0, whereas the etch rate of SiO2 is proportional to [CF2]. Both the etching and the deposition reactions proceed at the same time. Based on these observations, reaction mechanisms for fluorocarbon polymer deposition and SiO2 etching are analyzed.