DISCHARGE CHARACTERISTICS FOR MAGNETRON SPUTTERING OF AL IN AR AND AR-O-2 MIXTURES

An Al target has been sputtered in a planar magnetron system using argon and argon-oxygen mixtures at pressures from 0. 1 to 2 Pa. The characteristics of both dc and rf discharges have been investigated. In the dc case, the current is given by a relation of the form KV**n where V is the applied voltage and K and n are pressure-dependent parameters. Values of n p to 9 were obtained at the higher pressures but n decreased at lower pressures. For the rf discharge, the target self-bias voltage, V//s//b, at a given power decreased with decreasing pressure and was related to the average rf power by a relationship of the form CV//s//b/(V//s//b minus V) where V was approximately 1000 V and C decreased from 900 to 500 W with increasing argon pressure.