High-power pulsed sputtering using a magnetron with enhanced plasma confinement

Abstract

High-power pulsed dc magnetron discharges for ionized high-rate sputtering of metallic films were systematically investigated. The depositions were performed using two unbalanced circular magnetrons of different types with a directly water-cooled planar copper target of 100mm in diameter. The repetition frequency was 1kHz at a fixed 20% duty cycle and an argon pressure of 0.5Pa. Time evolutions of the discharge characteristics were measured to provide information on absorption of energy in the discharge plasma and on transfer of arising ions to the substrate at a target power density in a pulse up to 950W∕cm2. Time-averaged mass spectroscopy was performed at the substrate position to characterize ion energy distributions and composition of total ion fluxes onto the substrate. The deposition rate of the copper films formed on a floating substrate at the distance of 100mm from the target was 2.2μm∕min at an average target power density over a pulse period of 96W∕cm2. Very effective ionization of sputtered copper atoms resulted in a strong predominance of copper ions (up to 92%) in total ion fluxes onto the substrate. Trends in measured values of the deposition rate per average target power density and the ionized fraction of sputtered copper atoms in the flux onto the substrate (up to 56%) were explained on the basis of model predictions.