DEVELOPMENT OF A HIGH-PRECISION ELECTRON DENSITY MEASUREMENT TECHNIQUE FOR MULTILAYER FILMS

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An X-ray reflectometer with a crystal monochromator and analyzer has been designed for high-precision determination of electron of density profiles in multilayr films. Use of an asymmetric channel-cut silicon monochromator resulted in an X-ray beam intensity one order of magnetitue greater than in the conventional design. For data analysis a package of computer codes has been prepared using the scattering theory based on the distorted-wave Born approximation, which allows us to determine the interface roughness and its correlations in the in-plane and out-of-plane directions from specular and non-specular diffuse scattering data collected over a large range of scattering angle including the total-external reflection region. The system has bee applied to the determination of layr thicknesses and their variation, interface roughness in semiconductor SiGe/Si superlattices and magnetic multilayrs including Gd Co and Gd layrs, an Al/C nanolayrs. It was found that the replication of surfacestep structure on a vicinal siicon substrate strongly depends on the alloy composition of Ge in the SiGe layr. The system was proved useful in the structure characterization of magnetic multilayrs for X-ray resonant magnetic scattering experiments at synchrotron sources. It was also applied to a model-independent determination of electron density profiles in Al/C films from anomalous dispertion X-ray reflectometry data.