In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity to $SiO_2$ and $HfO_2$) of TiN thin films in the $CH_4$/Ar inductively coupled plasma. The maximum etch rate of $274;{AA}/min$ for TiN thin films was obtained at $CH_4$(80%)/Ar(20%) gas mixing ratio. At the same time, the etch rate was measured as function of the etching parameters such as RF power, Bias power, and process pressure. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as showed an accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the $CH_4$ containing plasmas.