Characterization of WC x /B 4 C multilayers sputtered in argon/methane atmospheres

Abstract

A series of six WC(x)/B4C multilayers was produced by dc magnetron sputtering in an atmosphere of argon with methane additions (from 0 to 15 percent). The microstructure and chemistry of these multilayers was studied using transmission/HREM, XRD, XPS, electron probe microanalysis, and ion beam analysis with MeV helium beams. The multilayers were shown to be completely amorphous. In addition to carbon incorporation, a significant amount of hydrogen was incorporated. The amounts of hydrogen and carbon present increased with the percentage of methane (up to the 12 percent sample), but the atom percent of argon in the multilayers was constant, regardless of the methane concentration. It was found that reflectivity values for Mg K-alpha radiation improved as the methane concentration increased, with the sample produced in a 12 percent methane atmosphere showing the highest reflectivity. Annealing of a representative sample caused a significant loss of hydrogen, and a decrease of the bilayer spacing.