Carbon based Thin Films Prepared by HiPIMS and DCMS

Sammanfattning: The present thesis focuses on carbon based thin films prepared by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). The properties of such thin films can be tailored to an extensive variety; the film microstructure, for example, ranges in the presented work from fully amorphous, graphitic films to fullerene like (FL). Consequently, the applications of these films migh be as wide spread as their properties. Carbon nitride (CNx, 0 < x < 0.20) as well as carbon fluoride (CFx 0.16 < x < 0.35)thin films were synthesized in an industrial deposition chamber by reactive sputtering  ofgraphite in an Ar/N2 and Ar/CF4 ambient. In order to gain a better understanding of thegrowth processes the C/Ar/N2 and the C/Ar/CF4 plasma was investigated by ion massspectroscopy at room temperature. Further understanding in this context gave thedetailed evaluation of target current and target voltage waveforms, acquired whengraphite was sputtered in HiPIMS mode. First principle calculations were carried out forthe growth of CFx and gave additional grasp about the most probable plasma precursorsas well as structure defining defects. Data gained from these characterisations of thedeposition processes were successfully related to the film properties. In order to linkdifferent process parameters to film properties, the synthesized films werecharacterized with regards to their thickness and deposition rate (secondary electronmicroscopy, SEM), chemical composition (elastic recoil detection analysis, ERDA and xrayphotoelectron spectroscopy, XPS), the chemical bonding (XPS), microstructure (transmission electron spectroscopy, TEM and selected area electron diffraction, SAED).Another part on thin film characterization comprised measurements for possibleapplications. For this, mainly nanoindentation and surface energy measurements wereperformed. Application-related measurements revealed a hardness of up to 23 GPa at high elastic recoveries of ~ 90 % for CNx (x = 0.1) films that exhibited a weakly pronounced fullerene like structure. The hardness correlated with the microstructure and N incorporation rate of the thin film. Evidence by TEM for an increased amount of N intercalations in CNx HiPIMS thin films is supported by ion mass spectroscopic measurements. As expected, higher ion particle energies as well as amounts particularly for C+ and N+ were measured in the reactive HiPIMS plasma. CFx thin films were found to show surface energies equivalent to superhydrophobic material for x > 0.26 while such films were polymeric in nature accounting for hardnesses below 1 GPa. Whereas, an amorphous structure for carbon-based films with fluorine contents ranging between 16 % and 23 % was observed. For such films, the hardness increased with decreasing fluorine content and ranged between 16 GPa and 4 GPa.

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