X-ray reflectivity is a sensitive tool for characterizing interfaces in multilayers. Using an appropriate model, the low-angle θ-2θ spectra can be fit to yield the thickness and roughness of each layer. For Si/Mo, a model that includes an interlayer at the Mo on Si interface gives much better results than a simple bilayer model. Non-specular X-ray scattering measurements are particularly sensitive to roughness that is correlated from layer to layer because correlated roughness gives rise to reasonant scattering in particular non-specular directions. The non-specular behavior can be understood in terms of current theories of X-ray scattering from multilayers. Structural parameters, such as spatial frequencies of the correlated roughness and a coherence length for the correlations can be determined from these data. For the Si/Mo multilayers studied, spatial frequencies below 1/200 Å-1 are correlated throughout the multilayer.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics