Ti thin films deposited by high-power impulse magnetron sputtering in an industrial system: Process parameters for a low surface roughness
Nyasha J. Suliali, William E. Goosen, A. Janse van Vuuren, E.J. Olivier, Babak Bakhit, Hans Högberg, Vanya Darakchieva, J.R. Botha
Abstract
The influence of the choice of process parameters in an industrial high-power impulse magnetron sputtering (HiPIMS) system on the surface roughness and crystallinity of Ti coatings is presented in this work. A current density of 1 A/cm2 was kept constant by varying the pulse frequency to control the average power. The films were characterised by scanning electron microscopy, atomic force microscopy, X-ray diffraction and transmission electron microscopy. The surface roughness, residual stress and grain size are discussed as a function of the HiPIMS target average power in the 1.45–7.90 kW range. The surface roughness, ranging from 14 to 24 nm, is lower than that of the SnO2 glass substrate, and has a non-linear dependence on the HiPIMS power. X-ray 2θ diffraction shows (100), (001) and (101) orientation of the film crystallites. The peak shifts reveal a gradual reduction in residual stress as target power increases. Further, the effect of target power on crystal grain length and geometric orientation is also determined.