Deposition of Tantalum and Tantalum Oxide by Superimposed RF and D -C Sputtering

Abstract

The advantages and flexibility of glow discharge diode sputtering for the deposition of thin films can be greatly extended by the simultaneous application of a d ‐c and rf field at the cathode. The combined field increases the plasma density and prevents the formation of a dielectric film on the cathode during reactive sputtering. This technique allows: (i) operation at sputtering pressures of 0.5–2.0 millitorr with a tantalum deposition rate of ∼80 Aå/min, or a two ‐fold increase in tantalum deposition rate for pressures in the 10 to 20 millitorr range; (ii) high deposition rates (50 to 100 Aå/min) for the deposition of and by reactive sputtering in pure oxygen.