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Symposium on Plasma Surface Engineering at the Spring Meeting of the German Physical Society, Regensburg, 2002-03-11 to 2002-03-15
Abstract:
Despite the widespread use of low-temperature plasmas for deposition and erosion of thin films and
surface modification the underlying microscopic mechanisms are often not well understood,
especially for reactive plasmas. Thorough parameter studies and the use of modern in situ real-time
diagnostics of the plasmas as well as of the growing film provide valuable results to optimize the
processes. However, they generally allow only an indirect and therefore qualitative or even
ambiguous conclusion about the actual film growth processes. One reason is the complexity that is
inherently connected to such plasma processes. A vast number of particles with different energy and
reactivity is interacting simultaneously with the surface, thus hindering to reveal microscopic growth
mechanisms or reliable values of universal constants. One approach to isolate microscopic
mechanisms is the use of model experiments with quantified particle beams.
In this article model experiments for the example of amorphous hydrogenated carbon film (a-C:H)
growth will be motivated and described. The discrepancy between different experimental results and
various growth models proposed over the years are briefly reviewed. Recent results of the
particle–beam experiment during the last years established at the Max-Planck-Institut für
Plasmaphysik are presented. It will be shown, how the sticking probability of thermal methyl
radicals is influenced by substrate temperature and how the presence of other radicals such as
atomic hydrogen alter the sticking of methyl. Furthermore, it will be shown how ions participate in
film growth and the consequences for plasma experiments are discussed.
