X-ray reflectivity investigation of interlayer at interfaces of multilayer structures: application to Mo/Si multilayers

摘要

We report the effect of interlayer on multilayer X-ray reflectivity (XRR) profile using simulations at 8.047 keV (CuK_e???) energy. We distinguished the effect of interfacial roughness and in-depth interlayer on reflectivity profile. The interfacial roughness reduces the intensity of individual peak while the in-depth interlayer redistributed the reflectivity profile. We are able to discern the asymmetry in interlayer thickness at two interfaces if the interfacial roughness is small compared to in-depth interlayer thickness. The limitation is that, the sensitivity decreases with increasing interfacial roughness. This interlayer model is applied for electron beam evaporated Mo/Si multilayers. The Moa€“ona€“Si interlayer thickness is 10 ?± 0.5 ?… and Sia€“ona€“Mo interlayer thickness is 8 ?± 0.5 ?…. The nature of interfacial compound is identified using X-ray photoelectron spectroscopy (XPS). The mechanism of interlayer asymmetry is explained on the basis of different heats of sublimation of Mo and Si.