[Zurück]

C. Eisenmenger-Sittner, W. Vollnhofer, Ł. Ocypa, M. Piwko, Z. Rymuza:
"Nanotribological Behaviour Of Quasicrystalline Ultrathin Films Pvd Deposited On Silicon";
Vortrag: 6th International Colloquium MICRO TRIBOLOGY 2012, Osiek-Warsaw (eingeladen); 09.09.2012 - 13.09.2012.

The materials used in micro/nanotechnological applications like for the fabrication of e.g. molds used in nanoimprint lithography (NIL) or sliding components in MEMS/NEMS devices usually show poor tribological properties and, in particular, an inclination to sticking. Therefore we started to look for special coatings which can perform tribological functions and which also can be used as antisticking films. Complex metallic alloys (CMA) can be synthesized from abundant metallic constituents. One special sub-class of these materials are quasicrystals (QC) which show relatively low surface energy and good mechanical resistance against deformation and abrasion. Ultrathin QC films of Al59Cu25.5Fe12.5B3 with thicknesses below 500 nm were deposited by DC magnetron sputtering from composite targets. The challenges to the deposition process were (i) the production of sputtering targets suitable for DC magnetron sputtering with the correct, complex stoichiometry, (ii) the conservation of the stoichiometry in the deposited films and (iii) the achievement of good adhesion on the mold material. In the present paper we will discuss these deposition related points in detail. After solving the issues related to target production, coatings were deposited on single crystal silicon and were studied in a clean-room environment with a microtribometer based on an Atomic Force Microscope (AFM) Their tribological and adhesive properties were investigated. Additional wettability tests supported the results of the AFM tests. The effect of roughness on frictional and adhesive properties was identified. These extensive studies on plane silicon substrates, which led to an optimization of the film properties in respect to anti-sticking performance, will be presented and discussed in this report. Finally, first efforts were made to deposit the optimized coatings conformally onto high aspect ratio NIL moulds. Strategies to obtain a conformal coating on structured surfaces will be presented and first results based on these strategies will be shown.