X-ray optics is based on reflective multilayers with layer thicknesses of a few nanometers at most. The interface quality plays a central role in determining the final properties of these structures. However, the accurate characterization of such interfaces with the necessary quasi-atomic resolution is still a challenge. For this reason, we typically combine several characterization methods, such as X-ray reflectivity (XRR), X-rays photoelectron spectroscopy (XPS), ion scattering spectroscopy and Transmission Electron Microscopy (TEM), to get complementary information regarding the interface profiles. Here we investigated the resolution of Low-Energy Ion Scattering (LEIS) to characterize buried interfaces. The aim is to build a new approach to characterize interface profiles and provide complementary information to XRR and XPS.We investigated a strategy to assist spectra analysis with simulations and developed a method to quantify the effective width of interfaces from the tails of LEIS spectra.The resolution of LEIS tails proved to be higher than expected for interfaces that are buried less than 2nm from the surface. The method that we designed tested accurate and precise when compared to TEM measurements, with a precision of 0.1 nm.With this approach, we measured the effective width of Si-on-W interfaces and we were able to resolve a 0.1 nm difference in the effective interface width caused by different W thicknesses
