Density-related properties of metal oxide films

The density of the material in a deposited film determines many important film properties, for example hardness and abrasions resistance, adherence to the substrate, refractive index, film stress, flatness and film permeation. Chemical compound films like metal oxides, some nitrides and oxynitrides are mainly produced by reactive PVD processes. The energy input into the growing film strongly influence the density of the resulting film. High energetic coating conditions result e.g. in a high refractive index, but often also in relatively high residual optical absorption and high compressive film stress. In order to obtain films with improved properties immediately after deposition without time consuming post-deposition heat treatments, depositions of RLVIP-Ta2O5 films were carried out under relatively high oxygen pressures and under special rate conditions. The achieved reproducible film properties can practically be accepted for many low loss optical film applications.