Planar hollow cathode sputtering with asymmetrical voltage supply

This article studies a planar hollow cathode discharge (HCD) with an asymmetric negative potential applied to parallel cathodes. The hollow cathode effect is preserved when an additional high voltage bias is applied to one of cathodes. For the argon pressures of 15, 20 and 60 Pa, the current-voltage characteristics of the HCD were obtained with an extra bias voltage applied on the iron cathode/target. The paper describes the sputtering system based on a HCD, consisting of two cathodes: a flat target and a tungsten mesh located at a distance of 7 mm, through which the deposited material passes. At the argon pressure of 40 Pa, the dynamics of the local plasma parameters and the iron deposition rate on a substrate under floating potential located at a distance of 40 mm from the grid were measured. The asymmetrical voltage supply in hollow cathode sputtering lead to a significant increase in the iron sputtering rate (from 2 to 16 nm/min), which is associated with both an increase in the plasma density and the sputtering coefficient of the target material. Sputtering system based on a planar HCD is advantageous due to the absence of magnetic field, which facilitates deposition of soft magnetic materials. •The hollow cathode effect is preserved with asymmetrical voltage supply.•An extra bias voltage applied to the target reduces the discharge threshold voltage and increases parameters of plasma.•The asymmetrical voltage supply increases the target material sputtering rate.•Asymmetrical planar hollow cathode discharge can be used as an effective scalable sputtering system.