Different pulse techniques for stationary reactive sputtering with double ring magnetron

Abstract

Abstract Double Ring Magnetron (DRM) sources are suitable for stationary uniform coating of large substrates with metals, alloys and insulating layers. DRM sources are characterized by two concentric discharges on electrically insulated targets. Therefore, different pulse techniques in the frequency range between 10 and 100 kHz can be applied: (i) a voltage with alternating polarity between the inner and outer target (bipolar mode); (ii) a pulsed d.c. voltage for both of the targets (unipolar mode). Process parameters like energetic ion flux towards the substrate and thermal load as well as layer properties like mechanical stress and hardness are influenced by the pulse technique and the pulse parameters. Pulsed reactive sputtering allows a high rate deposition even of insulating compounds. Furthermore, unique materials such as compounds with multiple gas constituents (e.g. ternary compounds) or layers with changing composition (gradient layers) can be deposited. It will be shown that by adjusting the reactive gas flow ratio of oxygen and nitrogen, oxynitride layers with a defined composition and refractive index can be deposited. Gradient layers have been produced by changing the reactive gas flow ratio during deposition, including the appropriate adaptations of the reactive working point.