SIMPLE METHOD FOR THE CONTROL OF SUBSTRATE ION FLUXES USING AN UNBALANCED MAGNETRON

Substrate ion fluxes from unbalanced magnetron sources are generally c ontrolled by the use of additional magnetic fields. These methods are not always suitable for differentially controlling the ionic flux from multiple sources. We report here a simple method suitable for attaini ng such control that can be easily adapted to most unbalanced magnetro n systems. The flux leakage from an unbalanced magnetron is controlled by the use of a mild steel keeper with a detachable mild steel annulu s. The annulus redirects the unbalanced field lines through the keeper to the rear poles of the magnetron. The flux leakage is thus controll ed by varying the thickness of the annulus. Ion saturation currents me asured at the substrate, with and without a 0.9 mm thick mild steel an nulus, were found to differ by a factor of approximately 3 at an argon partial pressure of 1 mTorr. Furthermore we demonstrate that the chan ges in ion current density are achieved without alteration to the magn etron operating parameters. (C) 1998 American Vacuum Society.