X-ray and AFM studies of ultrthin films for EUV and soft X-ray applications

This film roughness and its correlation with the substrate microtopography are studied using x-ray scattering at L = 0.154 nm. The approach is applied for the investigation of superthin films of several nanometers thickness, when both interfaces are responsible for x-ray scattering, and consists in the direct determination of PSD functions from a set of x-ray scattering diagrams measured at different grazing angles of the probe beam. X-ray scattering methods are demonstrated to enable the quantitative evaluation of PSD functions of external film surfaces as well as the correlation between the substrate and film roughnesses. Results of measurements of thin films of materials widely used in the fabrication of short-period multilayer mirrors are discussed. The result of the x-ray scattering measurements are compared with independent investigations of the external film surface by atomic force microscopy.