Design and performance of a versatile, cost-effective microwave electron cyclotron resonance plasma source for surface and thin film processing

Abstract

A plasma source has been developed, which makes use of electron cyclotron microwave resonance conditions without cost-intensive tuning or other active elements. A magnetron typical of domestic microwave ovens is coupled to a cylindrical resonator of fixed dimensions. A high density plasma is maintained with permanent magnets. Sources have been designed for both high vacuum and ultrahigh vacuum environments. In the latter, microwaves are conducted by a coaxial feedthrough from the resonator to a ceramic plasma cup inside the vacuum chamber. This permits shorter working distances, resulting in higher beam densities at the sample. Ions are extracted from the plasma by grid assemblies. Beam energies are in the range from 30 to 2000 eV, with densities from a few μA/cm2 up to 10 mA/cm2, respectively. Predominantly neutral species are emitted using a specially designed, ceramic grid. Operating with O2 gas, a flux of neutral monomers of 2×1016/cm2 s has been measured by the oxidation of Ag films. The performance of the source is demonstrated in various surface and thin film processes, like ion beam sputtering, reactive ion beam deposition, as well as sputter cleaning and reactive etching of semiconductor materials.