Pressure Effects on HiPIMS Deposition of Hafnium Films
Surface and Coatings Technology
High power impulse magnetron sputtering (HiPIMS) was studied during the growth of hafnium films at argon pressures ranging from 0.80 to 5.33 Pa with a fixed pulse length (50 μs) and frequency (200 Hz). The effect of inert gas pressure on the plasma conditions and film structure was investigated. The peak target current increased with pressure, but its sensitivity decreased above 2.00 Pa, which corresponded to an increased ratio of ions to neutrals in the plasma. A comparison of plasma characteristics between Hf and Ti HiPIMS growth was made. In addition to pressure, the target currents were affected by the physical properties of the target material, particularly the secondary ionization energy and atomic mass. Sputtering gas rarefaction phenomena were found to be more pronounced for Hf, and as a result, the process characteristics and film properties had a strong interdependence on argon pressure discussed in this study. The microstructure of the hafnium films was analyzed with scanning electron microscopy and X-ray diffraction. When compared to Hf films deposited by dc magnetron sputtering, the HiPIMS process resulted in a decreased grain size and promoted the growth of the (100) orientation in the Hf films. These results demonstrate that Hf HiPIMS sputtering regimes have much stronger dependence on the working gas pressure compared to titanium, and these need to be taken into account to ensure that films are dense and have the desired morphology and crystallographic orientation.
Copyright © 2012, Elsevier
Reed, Amber N.; Lange, Matthew A.; Muratore, Christopher; Bultman, John E.; Jones, John G.; and Voevodin, Andrey A., "Pressure Effects on HiPIMS Deposition of Hafnium Films" (2012). Chemical and Materials Engineering Faculty Publications. 132.