Dependence of ion current on magnetic unbalancing in high power pulsed magnetron glow discharge

A high-power pulsed sputtering (HPPS) discharge is able to generate high ionization metallic plasma by applying a negative high voltage pulse-train with low duty ratio and high current capacity to a sputtering target. If HPPS discharge technique is applied to unbalanced magnetron sputtering (UBMS) system which is one of the ionized sputtering, we will get the metallic plasma ionized more. The ion current of direct-current UBMS increases with increase in magnetic un-balancing. However, high-power pulsed UBMS does not necessarily have the same characteristics as dc-UBMS. We investigated a connection between the ion current to a collector electrode and the number of peripheral magnets in the sputter target. The collector current increased with increase in the number of the magnets, but the ratio of the collector current to the target current depended more strongly on average input power than that for dc-UBMS. It was found that the current ratio indicated the maximum of 18.8% at the input power of 400 W in the hpp-UBMS with the peripheral 10-magnets.