Paper SE+PS-ThM3
Self-organization of Plasma in RF Magnetron Sputtering

Thursday, October 24, 2019, 8:40 am, Room A215

Self-organization of magnetron plasma in so-called spokes has been previously reported for pulsed [1, 2] and continuous magnetron discharges [3]. In this presentation, we will demonstrate that spokes also form in oscillatory RF magnetron sputtering regime [4]. We used an ICCD camera and electrical probes to investigate the rotating plasma patterns. The spokes in RFMS were compared to the spokes in classical DCMS at similar discharge conditions. In both regimes, stable plasma patterns were observed for a wide range of discharge parameters. For similar gas pressures and discharge powers, the number of spokes in the RFMS regime was always larger than in the DCMS regime. The number of spokes changed sequentially with the increasing working gas pressure for both magnetron operations. In the DCMS regime, a single spoke was observed at the lowest argon pressure (0.25 Pa) and a second spoke was observed only at the highest pressure (2 Pa). In the same pressure range, the plasma in the RFMS regime displayed four spokes at the lowest pressure and six or seven spokes at the highest pressure. The influence of discharge power on the number of spokes was less pronounced for both magnetron regimes. Spoke patterns were analyzed by examining the inelastic collisions between electrons and argon atoms. For this purpose, we simulated the dissipation of electron energy in the drift direction and compared the calculations to the length and number of spokes for particular discharge conditions. Overall, the simulations agree well with the observed plasma patterns in DCMS and RFMS.

[1] A. Anders et al., J. Appl. Phys., 111 (2012) 053304

[2] A. Ehiasarian et al., Appl. Phys. Lett., 100 (2012) 11410

[3] M. Panjan et al., Plasma Sources Sci. Technol., 24 (2015) 065010

[4] M. Panjan accepted for publication in J. Appl. Phys. (2019)