Behavior of bipolar pulsed high-power impulse magnetron sputtering plasma studied using Langmuir probe

Bipolar pulsed high-power impulse magnetron sputtering (HiPIMS), incorporating a positive voltage reversal, was utilized for copper deposition. This research employed a custom-made Langmuir probe to measure plasma parameters. This custom-made probe can study the high-energy region of electron energy distribution function, where the temporal profiles of the probe current and floating potential were directly measured with a digital oscilloscope. Thus, the temporal evolution of ion saturation current, plasma densities, and plasma potential were determined. The results reveal that the positive voltage phase maintains high plasma density and stability. This study demonstrates that the positive reverse voltage can manipulate the plasma potential. An increase in plasma potential enhances ion kinetic energy, potentially improving film deposition quality through controlled ion bombardment. The findings suggest that bipolar pulsed HiPIMS can effectively control plasma characteristics, influencing film deposition properties. Apart from changes in potentials, the plasma properties of bipolar pulsed HiPIMS were found to be similar to those of unipolar HiPIMS.