NOVEL RADIOFREQUENCY INDUCTION PLASMA PROCESSING TECHNIQUES

A novel plasma source combining rf inductive drive and multipole plasma confinement has been constructed to process advanced semiconductor materials. Measurements show a linear dependence of density with input power. Ion current efficiencies of 1 A per 150-300 W of input power can be achieved in argon, with lower efficiencies in electronegative gases. Applying an rf bias to a substrate immersed in the plasma allows the sheath voltage to be controlled between 8 and 300 V. Insight into the rf induction process can be gained by a simple circuit model, which represents the induction process with a transformer. The physical quantities describing the transformer can be obtained from numerical calculation of the fields of the induction coil. This plasma source can etch thin films at rates exceeding 1 mum/min.