Enhanced sputtering of titanium oxide, nitride and oxynitride thin films by the reactive gas pulsing technique

The reactive gas pulsing technique was used to deposit titanium oxide, nitride and oxynitride thin films by d.c. reactive magnetron sputtering. A pure titanium target was sputtered in a mixture of Ar+O2 for TiOx, Ar+N2 for TiNy and Ar+O2+N2 for TiOxNy. The reactive gas was injected with a well-controlled pulsing method for titanium oxide and nitride whereas titanium oxynitride were prepared with a constant flow rate of nitrogen and a pulsing flow rate of oxygen. A constant pulsing period was used for every deposition and the injection time of the reactive gas was systematically changed. Instability phenomena typical to the reactive process were prevented by this technique. An improvement of the deposition rate of TiO2 and TiN thin films was achieved. The modulation of the reactive gas injection time allowed to change the crystallographic structure of the material as well as the chemical composition (1.4<x<2.0 for TiOx and 0.45<y<1.06 for TiNy). With two reactive gases, the pulsing technique appeared as an original way to prepare titanium oxynitride with every x, y composition. Real time measurements of the Ti target potential were used as process parameters in relation to the changes in TiOx, TiNy and TiOxNy thin film properties.