In this study, the effect of the dry etching of titanium dioxide (TiO2) thin films was investigated with addition of O2 to BCl3/Ar plasma. The maximum etch rate of TiO2 thin films and the selectivity of TiO2 to SiO2 were 100 nm/min and 1.07 in O2/BCl3/Ar (= 3:4:16 sccm) plasma, respectively. In addition, the etch rate and selectivity were measured as functions of the etching parameters, such as the gas mixing ratio, RF power, DC-bias voltage, and process pressure. The chemical state on the etched surface of TiO2 thin films were investigated by the x-ray photoelectron spectroscopy. To determine the re-deposition and reorganization of residues on the surface, the surface morphology and roughness of TiO2 thin films were examined by the atomic force microscopy.