A New AC Sputtering Technique for the Deposition of Thin Films

An ac sputtering technique is described which utilizes an array of tubular target electrodes. Reduced substrate heating is achieved by a combination of efficient cooling of the target electrodes and the unique geometry of the target array. Because substrate heating is reduced, capacitor grade beta-tantalum films have been deposited at 450 Å/min; a two-fold increase over maximum deposition rates for such films in a conventional dc sputtering process. Alloy films can be conveniently deposited with this ac sputtering method. The alloy composition is selected and controlled by electrical means. This concept has bean successfully applied to the deposition of tantalum-aluminum alloy films.