X-ray scattering study of interfacial roughness correlation in Mo/Si multilayers fabricated by ion beam sputtering

摘要

Specular and diffuse x-ray scattering are used to probe the mesoscopic structure of interfaces within two 30-period Mo/Si superlattices, grown on silicon and glass substrates by ion beam sputtering. The data are evaluated qualitatively and quantitatively on the basis of a distorted-wave Born approximation, which includes a correlating behavior of interface roughness in both the lateral and vertical directions. Different initial conditions of the substrate's surface result in distinguishable characters of roughness replications in the direction of growth. The average value, lateral correlation and fractal dimension of roughness are found to be different in the two samples, which leads to differences in the reflective properties of multilayer mirrors.