On the film density using high power impulse magnetron sputtering, 2010, SURFACE and COATINGS TECHNOLOGY, (205) AbstractThe influence on thin film density using high power impulse magnetron sputtering (HiPIMS) has been investigated for eight different target materials (Al, Ti, Cr, Cu, Zr, Ag, Ta, and Pt).The density values as well as deposition rates have been compared to results obtained from thin films grown by direct current magnetron sputtering (DCMS) under the same experimental conditions. Overall, it was found that the HiPIMS deposited coatings were approximately 5-15 % denser compared to the DCMS deposited coatings. This could be attributed to the increased metal ion bombardment commonly seen in HiPIMS discharges, which also was verified using a global plasma model to assess the degree of ionization of 2 sputtered metal. One key feature is that the momentum transfer between the growing film and the incoming metal ions is very efficient due to the equal mass of film and bombarding species, leading to a less pronounced columnar microstructure. As expected the deposition rates were found to be lower for HiPIMS compared to DCMS. For several materials this decrease is not as pronounced as previously reported in the literature, which is shown in the case of Ta, Pt, and Ag with rate HiPIMS /rate DCMS ~ 70-85 %, while still achieving denser coatings.

ZrB 2 thin films were grown on Si by high power impulse magnetron sputtering (HiPIMS) from a compound target in an industrial deposition system. By keeping a constant average power while modifying the HiPIMS pulse repetition frequency, the pulse peak current and thereby the degree of ionisation was varied. The films were characterised using X-ray diffraction techniques, scanning electron microscopy, time-of-flight elastic recoil detection analysis, and four-point probe measurements. It was found that the composition of the films matched closely that of the target material, and the films were low in contamination. The films were crystalline with a strong (000n) preferred orientation, and that the residual stress could be adjusted, from tensile to compressive, by increasing the degree of ionisation. The film morphology appeared dense, with a smooth surface, and the resistivity was found to range from 180 to 250 µΩcm with no clear dependence on frequency in the investigated parameter range.

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