Exploring different approaches of multipulse HiPIMS

Three different approaches for using high power impulse magnetron sputtering (HiPIMS) with a titanium target were examined in terms of plasma diagnostics and coating properties. In all three approaches, a 1kW average power was kept constant. The first approach involves splitting a strong single HiPIMS pulse into multiple evenly distributed weaker pulses by proportionally dividing the period. The second approach is based on the first one, but the pulses are grouped together in a short burst, or pulse package, where the overall period is conserved. Comparing the second approach to the first enables the identification of the effect of pulse grouping. In the third approach, the pulses are also grouped into the pulse package, however, the period is extended proportionally to the number of pulses in the pulse package. This allows for the creation of short bursts of energetic pulses separated by very long off-times while maintaining the duty cycle. In this way, it is possible to determine whether the grouping of the strong pulses into a pulse package is more beneficial for the deposition than the negative effects induced by prolonging the off-time. Plasma diagnostics revealed that grouping the pulses into packages in the second approach resulted in a higher ionised metal flux fraction on the substrate compared to the first approach, which led to stronger ion bombardment of the growing coating, resulting in denser coatings and changes in the crystalline microstructure. The third approach did not increase ionised metal flux fraction significantly but influenced the texture and grain size of the growing films. •Multi-pulse HiPIMS operation enables the tuning sputtering process.•Multi-pulse operation enables ion flux and deposition rate adjustments.•By grouping the pulses, denser and smoother layers are deposited.•Grain size and preferential growth orientation can be tuned by a number of pulses.