Gas flow sputtering of oxide coatings: Practical aspects of the process

On the basis of the principle of reactive gas flow sputtering, advanced sputtering sources for metals and hard coatings have been developed. Main features of these sources, which are based on an intense hollow cathode glow discharge and an inert gas flow supported material transport to the substrate, are the high deposition rates (in the order of 10-20 mm h-¹), the operation at a low vacuum level (1 mbar range) and the applicability to a wide range of coating materials. Oxide coatings of aluminum, titanium and zirconium have been deposited; furthermore, corresponding pure metals and high temperature superconductor films (YBaCuO) also. Linear upscaling to 0.5 m source length suggests that there are no principle limits for large area coating. The 3D behavior follows from the directed gas flow and the isotropic out-diffusion from the carrier gas, i.e., it displays characteristics between PVD and CVD. A long-term stability up to 65 h of continuous operation has been demonstrated.