Particle-beam experiment to study heterogeneous surface reactions relevant to plasma-assisted thin film growth and etching

Abstract

An ultrahigh-vacuum-based particle-beam experiment to study heterogeneous surface reactions relevant to plasma–surface interaction processes is presented. The experiment comprises two radical beam sources and a source for low energy ions. As diagnostic tools real-time in situ ellipsometry and infrared spectroscopy are implemented. The infrared sensitivity for thin films is enhanced through application of an optical cavity substrate. The fluxes of the radical beam sources are quantified absolutely for the production of hydrogen atoms and methyl radicals. The ion source is also quantified for a wide variety of ionic species, e.g., He+, Ar+, H+, H2+, H3+, and CH3+. Ion energies from above 1 keV down to 1 eV are achievable. The setup allows one to investigate heterogeneous surface processes of one single species or simultaneous interaction of up to three different, individually controllable species with a surface of interest. By running the radical sources to produce hydrogen and methyl radicals and the ion source with the ions mentioned, microscopic surface processes relevant to deposition and erosion of hydrocarbon layers in low-pressure gas discharges were studied in great detail. Sample results for the hydrogen CH3 growth synergism, ion-assisted film growth, and chemical sputtering are presented to demonstrate the capability of the setup.