High power impulse magnetron sputtering under industrial conditions

• In this thesis, the recent development step of magnetron sputtering, termed high power impulse magnetron sputtering (HiPIMS) has been studied. Compared to conventional magnetron sputtering HiPIMS provides a higher plasma density which can ionise the sputtered material. The beneficial influence of the coating properties due to this ionisation has been extensively shown in academic publications. Here, industrial conditions, i.e. no substrate heating and high vacuum conditions have been used during the studies, of which one was performed in an industrial deposition system.For eight metallic targets, films were deposited with HiPIMS and conventional sputtering. The films were evaluated by Rutherford back scattering analysis, scanning electron microscopy, and profilometry. It was found that the density of the HiPIMS grown films exhibited a statistically significant higher density of approximately 5-15% in comparison to films deposited using DCMS under identical conditions. A global plasma model was employed to evaluate the degree of ionisation for some of the target materials, and process conditions used in the study. Conformity between density increase and degree of ionisation as assessed by the plasma model was confirmed.The influence of using HiPIMS during reactive sputtering of TiC was also studied. A metallic Ti target was sputtered in a gas mixture of Ar and C2H2. The coatings were evaluated by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, 4 point probe resistivity measurements, and nanoindentation. The coatings were found to be nanocomposite TiC/a-C:H. For the HiPIMS process the transition zone between metallic and compound target states was found to be significantly expanded over a wide reactive gas flow range. The implications of choice of deposition method for coating composition, chemical structure, as well as electrical and mechanical properties were evaluated for DCMS and HiPIMS. The process behaviour was suggested to be due to the pulsed nature of the HiPIMS, the high plasma density, and ion content of the particles reaching the substrate.

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NATURAL SCIENCES

NATURVETENSKAP

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vet (subject category)

lic (subject category)