INTERFACE STABILITY AND SILICIDE FORMATION IN HIGH-TEMPERATURE STABLEMOXSI1-X SI MULTILAYER SOFT-X-RAY MIRRORS STUDIED BY MEANS OF X-RAY-DIFFRACTION AND HRTEM/

Multilayer thin films consisting of alternating pure molybdenum and si licon layers with layer thicknesses of a few nanometers are of increas ing interest for soft X-ray optical applications in the wavelength reg ion above the Si-L edge (lambda = 12.4 nm). In order to enhance the th ermal and long term stability, which is of great importance for applic ations with high power soft X-ray sources, interdiffusion of molybdenu m and silicon as a mechanism of thermal destruction of the multilayer system has to be reduced. For this purpose multilayers with absorber l ayers of two different Mo(x)Si1-x mixtures, Mo0.5Si0.5/Si and Mo0.33Si 0.67/Si, and a double-layer thickness of about 7 nm are prepared by el ectron beam evaporation in a UHV system. The thermal stability for bot h systems is studied by post deposition annealing at different tempera tures. For each temperature interdiffusion and interfacial roughness o f the multilayers are examined by small angle X-ray diffraction (SAXD) at lambda = 0.154 nm, while the formation of nanocrystallites with la ttice plane orientation parallel to the layer system is investigated b y large angle X-ray diffraction (LAXD). In the case of the Mo0.5Si0.5/ Si multilayer system these studies are completed by high resolution tr ansmission electron microscopy (HRTEM) at multilayer cross sections an d optical diffraction measurements (ODM).