The effect of deposition parameters on the phase of TiO₂ films grown by RF magnetron sputtering

TiO₂ thin films were deposited on Si substrates by using conventional radio-frequency (RF) magnetron sputtering with either metallic Ti or TiO₂ targets, and the effect of the deposition parameters (substrate temperature (T_s), RF sputtering power, gas flow ratio of O₂/(Ar+O₂) and deposition time) on the phase of the film was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to obtain information on the phase of the films and on the surface image/thickness of films, respectively. TiO₂ films deposited at a T_s higher than 300 °C by using a metallic Ti target showed the dominant presence of the rutile phase. For films grown at a constant T_s of 300 °C with different gas flow ratios of O₂/(Ar+O₂), the amount of the rutile phase gradually decreased as the oxygen gas flow was decreased. The anatase phase, however, was formed when the O₂/(Ar+O₂) was 0.2. On the other hand, for TiO₂ films deposited at T_s’s between 50 °C and 200 °C with an O₂/(Ar+O₂) of 0.1 by using a TiO₂ target, both the anatase and the rutile phases gradually decreased as the T_s was increased. For TiO₂ films deposited with various gas flow ratios of O₂/(Ar+O₂) between 0 and 0.4 at a constant T_s of 200 °C by using a TiO₂ target, the anatase phase gradually decreased, but the rutile phase gradually increased, as the gas flow ratio was increased.