X-ray standing wave and reflectometric characterization of multilayer structures

Abstract

A microstructural characterization of synthetic periodic multilayers by x-ray standing waves is presented. It is shown that the analysis of multilayers by combined x-ray reflectometry (XRR) and x-ray standing-wave (XSW) techniques can overcome the deficiencies of the individual techniques in microstructural analysis. While interface roughnesses are more accurately determined by the XRR technique, the layer composition is more accurately determined by the XSW technique, where an element is directly identified by its characteristic emission. These aspects are explained with an example of a 20-period Pt/C multilayer. The composition of the C layers due to Pt dissolution in the C layers, Pt_xC_1-x, is determined by the XSW technique. In the XSW analysis, when the entire amount of Pt present in the C layers is assumed to be within the broadened interface, this leads to larger interface roughness values, inconsistent with those determined by the XRR technique. Constraining the interface roughness values to those determined by the XRR technique requires an additional amount of dissolved Pt in the C layers to explain the Pt fluorescence yield excited by the standing-wave field. This analysis provides the average composition Pt_xC_1-x of the C layers.