Invited Paper SE+PS+TF-MoA3
Understanding the Physics of Magnetron Discharges: Ionization Zones and Their Role in Transport of Charged Particles

Monday, November 10, 2014, 2:40 pm, Room 302

Magnetron sputtering is one of most commonly used techniques for the deposition of thin films. The physics of magnetron discharges has been intensively studied, however, recent investigations revealed that our understanding is rather incomplete. To the naked eye the ionization process appears to be homogeneously distributed along the racetrack – i.e. the region of strongest target erosion caused by sputtering. Imaging of the magnetron discharges with intensified CCD cameras using short exposure times revealed differently, namely, the plasma is concentrated in several zones along the racetrack [1-3]. These so-called ionization zones or spokes are organized in periodic or quasi-periodic patterns that move in the E × B direction with approximately 1/10 of the electron drift speed (where E and B are the electric field and magnetic field vectors). Recent experiments further revealed that ionization zones are a fundamental feature of magnetron discharges run in pulsed and continuous mode [4]. In this talk, recent advances in understanding the ionization zone phenomenon will be reviewed. The interpretation of the formation, drift, self-sustainability, and self-organization of ionization zones will be presented with emphasis on potential, electric field and ionization rate distributions. It will be shown that ionization zones play a critical role in the transport of both electrons and ions [4-6].

[1] A. Kozyrev et al., Plasma Physics Reports 37 (2011) 621

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

[3] A.P. Ehiasarian et al., Appl. Phys. Lett. 100 (2012) 114101

[4] M. Panjan et al., Plasma Sources Sci. Technol., 23 (2014) 025007

[5] A. Anders et al., Appl. Phys. Lett., 103 (2013) 144103

[6] P.A. Ni et al., Appl. Phys. Lett., 101 (2012) 224102