Effect of peak discharge current on the ion current density on the substrate in the short-pulse HiPIMS

The bombardment of the substrate with accelerated ions from the plasma during the magnetron sputtering process is an effective way of controlling the energy transfer to the coating. One of the ways to increase the ion flux on the substrate is to change the parameters of the discharge power supply pulses. This work investigates the effect of the discharge current pulse amplitude on the average ion current density on the substrate in short-pulse high power impulse magnetron sputtering (s-HiPIMS). During sputtering, the peak discharge current varied from 25 to 250 A with a fixed pulse duration of 6 μs and an average discharge power of 1 kW. Experimental results and theoretical calculations show that the average ion current density on the substrate increases twofold when the amplitude of the discharge current pulses is increased from 25 to 60 A. As the amplitude of the discharge current pulses is further increased, the average ion current density on the substrate stops growing and begins to decrease at currents above 150 A. The paper discusses the reasons for the nonlinear dependence of the average ion current density on the substrate on the amplitude of the discharge current pulses.