Abstract: In the last years a variety of plasma sources have been developed for film depositionby plasma activated deposition techniques. In addition to RF- and DC-sources, pulsedplasma sources are gaining increased attention. This interest is driven by the wish ofdepositing coatings with superior properties as compared to those deposited by conven-tional techniques. One prominent example of coatings that are significantly enhancedby the usage of pulsed plasmas is alumina. Although crystalline α-alumina can be de-posited by thermal CVD at temperatures above 1000℃ for two decades, no process forthe deposition of crystalline alumina on heat sensitive substrates like tempered steelsat low temperatures is commercially available up to now. In this paper, the depositionof alumina films from gaseous mixtures of AlCls-N2-H2-Ar in a bipolar pulsed glowdischarge at about 500℃ is reported. Special attention was paid on the correlation be-tween plasma characteristics and film properties. The measurements revealed that theproperties of the resulting coatings were significantly influenced by the characteristicsof the power supply. Depending on the gas composition and the plasma parameters,alumina films with high hardness and good adhesion were deposited.

Key words: alumina, PECVD, structure, bipolar pulsed glow discharge