Tailored plasmas for applications in the surface treatment of materials

We describe the development and diagnosis of a two-stage plasma discharge in which a source plasma is separated from a secondary process plasma by a fine mesh. Through the application of a DC bias potential to the mesh the electron temperature Te and mean ion bombarding energy Ei to an electrically isolating substrate can be well controlled in the secondary discharge. Electrical probe and retarding field analyser measurements have shown that Te and Ei can be varied in the range 0.2–4 and 1–26 eV, respectively, and are found to be spatially uniform. Using this system, the bombarding ion flux can also be varied in the range from 1017 to 1019 m−2 s−1, independently of the ion energy through the combined variation of the primary discharge power, and pressure and substrate location. These types of plasmas may find applications in the controlled plasma modification of materials through tailoring of the ion energy and flux.