On the ion flux and energy gain during pulsed DC operation of an opposed target magnetron

Abstract

Pulsed DC operation of sputtering magnetrons brings higher ion energies and fluxes to the substrate, both having a strong influence on the deposited layer properties. As phenomena leading to an increase in the ion flux and energy at substrate during pulsed DC deposition are still not fully understood, it is therefore important to develop a model that explains the gain in the ion flux and energy and its temporal evolution during the pulse-off time. An opposed target (Penning type) magnetron has been used for the experimental study. The ion energy spectra (IES) at the substrate region are investigated using an EQP-300 (HIDEN Analytical) energy analyser during pulsed DC magnetron operation at 50 kHz, pulse widths between 496 and 8016 ns, and constant current run of 2 A, at 0.4 Pa Ar gas pressure. Based on the measured current and voltage waveforms on the cathodes and the IES at the substrate, a physical model for the ion energy and flux gain during the pulse-off time is proposed. The model is validated through analysis of the ion flux and ion flux rate at the substrate region and by space-resolved IES measurements.