Electron-Wave Interaction in a Planar Sputtering Magnetron

Indianapolis, IN

Magnetrons are plasma devices used in thin film processes and sputter etching. In a magnetron, crossed E and B fields confine a plasma to the surface of a target cathode which, through bombardment by unmagnetized ions in the plasma, is the source of sputtering emission. In this paper, a computational model for a circular, planar sputtering magnetron is developed, in which the bulk plasma behavior is modeled via the cloud-in-cell (CIC) method and the energetic ionizing electrons by direct simulation of discrete particles. The confined plasma in a sputtering magnetron allows for the propagation of waves; in particular, the interaction between acoustic waves travelling in the axial direction and energetic electrons is the focus of this study. These waves should transfer enough energy to electrons to allow them to escape confinement, resulting in a lower electron density in the confined plasma than previous models have predicted.