@phdthesis{Drache2015,
  author    = {Steffen Drache},
  title     = {Deposition of nanostructured Cu-Ti based films by advanced magnetron sputtering methods},
  journal    = {-},
  url       = {https://nbn-resolving.org/urn:nbn:de:gbv:9-002289-5},
  year      = {2015},
  abstract  = {A system for the deposition of intermetallic Cu-Ti based films by magnetron sputtering was developed, built up and characterized by different plasma diagnostics. The dual and externally triggerable power electronics with high parallel capacity allows the pulsing of both magnetrons against each other at an arbitrary frequency f, duty cycle t\_a/T and pulse delay t\_d. This way, apart from conventional pulse modes (dual-MS: f = 4.6 kHz, t\_a/T = 50 \%), also high power impulse magnetron sputtering (dual-HiPIMS: f = 100 Hz, t\_a/T = 1 \%) can be put into effect. Further, the different sputtering yields of Ti and Cu can be compensated by individual mean discharge currents. The discharge characteristics show very high pulse currents (I > 50 A) during HiPIMS. Langmuir probe measurements verify higher electron densities (n\_e = 10^18 m^-3) and a broader electron energy distribution in contrast to dual-MS. As a result, stronger ionization and excitation of plasma species can be observed by optical emission spectroscopy (OES). Spectrally integrated OES was used to describe the spatiotemporal discharge evolution. The velocity distribution function of ions, that are important for the film generation ,are attained time-resolved with a retarding field energy analyzer. The deposited films were analyzed by x-ray diagnostics and their properties interpreted with respect to the film growth at different discharge modes. Film thickness, crystallinity and mass density reveal an obvious dependency on the discharge mode with mainly higher quality in case of HiPIMS. The variation of the mean Cu discharge current allows to influence the films elemental composition that is decisive for practical applications. Further composite films based on Cu nanoparticles (clusters) embedded into a dielectric matrix material (TiO2) were synthesized and analyzed. First the Cu cluster growth during a novel buffer gas pulsing method was studied time-resolved. It involved the performance evaluation of the particle source based on a simple model. As a result the size/mass distribution and by that the properties of the clusters can be influenced in a simple manner. Finally the Cu-TiO2 composite films were produced in a specifically designed codeposition system. Thereby the Cu clusters emitted from the gas aggregation source are deposited simultaneously with reactively (plus O2) sputtered Ti. Separately deposited Cu clusters mainly show polycrystalline fcc-Cu that forms a thin surface layer of Cu2O when in contact with ambient air or after molecular oxygen admixture. While the film of separately and reactively deposited Ti forms titanium dioxide (TiO2) the Cu of the nanocomposite reveals differences in its structure: In the nanocomposite Cu is not metallic anymore, but completely converted to CuO. This is caused by the presence of a reactive oxygen plasma during the codeposition. It could be shown that molecular O2 can only form a diffusion limited amount of Cu2O, while discharge activated oxygen species lead to a complete oxidation of the Cu clusters to CuO. This is an important finding for future synthesis of similar composite materials.},
  language  = {de}
}