Optical and thin film properties of mixed oxides deposited by pulsed reactive magnetron sputtering

Reactive magnetron sputtering was used to deposit optical thin films. In order to obtain high deposition rates, metallic targets were used. For the creation of mixed oxides bipolar pulsed sputtering was applied to two different targets. A new process control setup was developed to monitor the oxidation state of both targets individually. Two different elemental targets are co-sputtered in oxygen-argon atmosphere within the lambda-probe stabilized transition mode. The composition is controlled by optical emission spectroscopy. Thus different mixtures are accessible without changing target material. Varied mixtures in the system hafnia-silica have been prepared. The optical properties (refractive indices, absorption, surface roughness, density) as well as mechanical behavior (film stress, hardness) of the mixtures are compared to pure oxide materials. By mixing the oxides thin film quality can be improved beyond the properties of the single materials.