Prozeßuntersuchung eines innovativen Plasmaverfahrens zur Herstellung funktioneil gradierter Metall-Nichtmetall-Schichten

The understanding of the plasma based processes which take place during the deposition of thin films is a prerequisite to deposit complex layer systems. The deposition of metallic and non-metallic films using dense plasmas in combination with suitable in-situdiagnostics is described in this paper. In the experiment dense He- and Ar-plasmas were generated by a low pressure arc discharge using a hollow LaB$_{6}$-cathode in the plasma facility PETRA (Plasma Engineering and Technology Research Assembly). Typical values for the density and electron temperature were n$_{e}$ = 10$^{12}$..10$^{13}$ cm$^{-3}$ and kT$_{e}$ = 5..20 eV. The influence of different configurations of the magnetic field (homogeneous and cusp) were investigated in view of homogenity of the layers and the deposition rate. Usually the adhesion of non-metallic films (a-C:H) on metal substrates is limited by the high internal stresses of the coating and the poor interfacial contact between coating and substrate. A concept to improve the adhesion of coatings is to introduce a metal interlayer (Al) with a gradient transition to the non-metal coating. For the deposition of homogeneous coatings a combination of plasma assisted PVD and CVD methods was used. The coatings were characterised by SEM, EDS, TEM/TED, IR-spectroscopy, Raman-spectroscopy and SIMS analyses as well as microindentation measurements. The influence of different parameters on the plasma and the local distribution of plasma density and electron temperature were measured by electric double probes. Mass spectrometry showed that the introduced hydrocarbon gases (CH$_{4}$ or C$_{2}$H$_{2}$) were almost completely dissociated by the plasma. The amount of hydrogen liberated from the dissociation process was strongly dependent on the reactive gases used. Space resolved optical emission spectroscopy allowed to measure the local enrichment of H, CH and CII species. Also the absolute densities of Al and Al$^{+}$ were determined. Additionally a 2-D-model of the local transport of Al-atoms and Al-ions within the plasma was developed. OES-measurements are in good agreement with the numerical results and the measured film deposition is consistent with the calculation