Recently, we developed a process control for the deposition of mixed oxides by reactive pulsed magnetron sputtering. A dual magnetron setup with two different metallic targets was used. Different closed-loop stabilizations were applied: one controlled the oxygen partial pressure by the help of a lambda-probe while two other regulated the mixture by means of optical emission spectroscopy at each target. The presented process system features low cost mixing of different materials with high flexibility because only standard pure metal targets are used within the transition mode. High refractive index materials for ultraviolet coatings like hafnium oxide or zirconium oxide suffer from high thin film stress. We show reduced stress values for mixing them with silicon oxide or aluminum oxide which also shifts the absorption edge to lower wavelengths. Thus the application range can be extended with higher refractive index than pure alumina. Besides we present optical properties (refractive indices, absorption, and surface roughness) and mechanical properties (film stress, hardness) of the mixtures that give the possibility to optimize the film characteristics beyond pure materials.
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