MONTE-CARLO SIMULATION OF IONIZATION IN A MAGNETRON PLASMA

A Monte Carlo simulation of electrons emitted from the cathode of a planar magnetron is tested against experiments that were reported by Wendt, Lieberman, and Meuth [J. Vac. Sci. Technol. A 6, 1827 (1988)] and by Gu and Lieberman [J. Vac. Sci. Technol. A 6, 2960 (1988)]. Comparing their measurements of the radial profile of current and the axial profile of optical emission to the ionization profiles predicted by the model, we find good agreement for a typical magnetic field strength of 456 G. We also find that at 456 G the product of the average number of ionizations <Ni> and the secondary electron emission coefficient γ is ∼1. This indicates that secondary emission contributes significantly to the ionization that sustains the discharge. At 171 G, however, <Ni>γ≪ 1, revealing that cathode emission is inadequate to sustain a discharge at a low magnetic field. © 1990, American Vacuum Society. All rights reserved.