Thin films deposited with unfiltered DC arc plasma from Ti, Ti0.75Al0.25, Ti0.50Al0.50, Ti0.30Al0.70, and Al cathodes were characterized with a scanning electron microscope for quantification of extent of macroparticle incorporation. Depositions were performed in N-2 atmosphere in the pressure range from 10(-6) Torr up to 3 . 10(-2) Torr, and the formation of cathode surface nitride contamination was identified from X-ray diffraction analysis. Visual observation and photographic fixation of the arc spot behavior was simultaneously performed. A reduction in macroparticle generation with decreasing Al content and increasing N-2 pressure was demonstrated. A correlated transformation of the arc from type 2 to the type 1 was visually detected and found to be a function of N-2 pressure and at of Al in the cathode. For the Ti cathode, no arc transformation was detected. These observations can be explained by a comparatively high electrical resistivity and high melting point of Al rich surface nitrides, promoting an arc transformation and a reduction in macropartide generation. (C) 2015 Elsevier B.V. All rights reserved.
Funding Agencies|European Research Council under the European Communitys Seventh Framework Program (FP7)/ERC [258509]; Swedish Research Council (VR) [642-2013-8020]; KAW Fellowship Program