Improvement of X-ray reflectivity calculation on surface and interface roughness

摘要

In the conventional X-ray reflectivity (XRR) analysis for the estimation of multilayer surface, the reflectivity is calculated based on the Parratt formalism, accounting for the effect of roughness by the theory of Nevot-Croce. However, the calculated results have shown often strange behaviour due to the fact that the diffuse scattering at the rough interface was not taken into account in the equation. Then we developed new improved formalism to correct this mistake. In this study, we show applying of new improved formalism using a transmission electron microscope (TEM) observation result. The result of interfacial roughness by using the conventional XRR formulae showed large difference with the TEM result, and derived wrong structure of surface. While, the result by new improved formalism reproduce the TEM result well, but need appropriate parameters in transmission coefficient. It shows that new improved XRR formalism derives more accurate analysis of the XRR, but the reduced Fresnel coefficients with physical grounds in the reflectivity equation are need in further research.