Multilayer coatings for x-ray mirrors: extraction of stack parameters from x-ray reflectivity scans and comparison with transmission electron microscopy results

The reflectance effectiveness of a multilayer depends strongly on the stack properties (thickness, roughness, and density of each layer) and can be directly tested by means of x-ray reflectivity scans at definite photon energies. The reflectivity curves are also a powerful tool for the in-depth, nondestructive characterization of the stack structure: The complex task of extracting the stack parameters from reflectivity curves can be achieved via a suitable best-fitting computer code based on a global automatic optimization procedure. We present the computer-assisted layer-by-layer analysis of the characteristics of Ni/C, Pt/C, and W/Si multilayers, based on x-ray reflectivity scans performed at 8.05 and 17.45 keV. In order to verify the correctness of the code predictions, we present also a comparison of the computer model with the transmission electron microscope profiles of the same multilayer samples.