Current-voltage-time characteristics in a reactive Ar/N_2 high power impulse magnetron sputtering discharge

摘要

The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N_2 discharge for 400 μs long pulses to explore the effect of nitrogen addition and the pulse repetition frequency. Adding nitrogen to an argon discharge leads to increased discharge current as the pulse repetition frequency is decreased. We argue that the secondary electron emission coefficient and its variation with surface condition and ion composition in the discharge plays a crucial role in determining the discharge current.