Auxiliary capacitor to enhance oscillation in circuit and reduce current onset delay in HiPIMS discharge: Theory, experiment and simulation

• Published in: Surface & coatings technology Vol. 405; p. 126518
• Main Authors: Han, Mingyue, Luo, Yang, Li, Hua, Li, LiuHe, Xu, Ye, Luo, Sida, Zhang, Peipei, Xu, Hao, Xu, Changyun
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.01.2021; Elsevier BV
• Subjects: Argon; Capacitors; Circuits; Current onset delay; Delay time; Discharge; ECO-HiPIMS; Electric potential; Electrodes; Gas breakdown; Gas pressure; HiPIMS; Low pressure; Magnetron sputtering; Parallel connected; PIC-MCC simulation; Plasma dynamics; Thin films; Voltage; HiPIMS; Current onset delay; Gas breakdown; PIC-MCC simulation; ECO-HiPIMS
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.126518

In high power impulse magnetron sputtering (HiPIMS) discharge, generally, the current onset lags the applied pulse voltage by a significant time which can reach to several tens of microseconds, especially at a low gas pressure. The existence of this delay will affect the instantaneous and average power, and in turn, it determines the plasma dynamics and the thin film properties. The origin of current onset delay can be traced back to gas breakdown in E × B fields. This work firstly focuses on the theory and model of gas breakdown in the HiPIMS discharge with parallel electrodes. Theoretically, the breakdown voltage of argon in HiPIMS is about −700 V at gas pressure of 0.45 Pa, while it can exceed −1100 V at pressure of 0.4 Pa. To operate the HiPIMS at a low pressure with a short delay time of current onset, the means using an auxiliary capacitor C connected in parallel with plasma between electrodes to enhance oscillation in circuit (named ECO-HiPIMS) is employed, which can generate a high oscillation voltage during the gas breakdown phase. Choosing a suitable capacitor, this oscillation voltage reaches up to −1322 V at applied pulse voltage of −700 V, and in turn, the delay time can be shortened from around 50 μs (in standard HiPIMS) to less than 5 μs. Finally, the plasma dynamics during gas breakdown phase in HiPIMS and ECO-HiPIMS has been investigated by a two-dimension particle in cell/Monte Carlo (2D PIC-MCC) simulation. •The theory of gas breakdown mechanism in HiPIMS is studied to estimate the breakdown voltage at various gas pressure.•The ECO-HiPIMS is used to generate a high voltage at the initial period of pulse and reduce the current onset delay.•The 2D PIC-MCC simulation is used to explore the plasma dynamics during the gas breakdown phase.