THERMAL-STABILITY OF MO/SI MULTILAYER SOFT-X-RAY MIRRORS FABRICATED BY ELECTRON-BEAM EVAPORATION

Mo/Si multilayers are fabricated by electron-beam evaporation in UHV at different temperatures (30-degrees-C, 150-degrees-C, 200-degrees-C) during deposition. After completion their thermal stability is tested by baking them at temperatures (T(bak)) between 200-degrees-C and 800-degrees-C in steps of 50-degrees-C or 100-degrees-C. After each baking step the multilayers are characterized by small angle Cu(Kalpha)-X-ray diffraction. Additionally, the normal incidence soft-X-ray reflectivity for wavelengths between 11 nm and 19 nm is determined after baking at 500-degrees-C. Furthermore, the layer structure of the multilayers is investigated by means of Rutherford Backscattering Spectroscopy (RBS) and sputter/Auger Electron Spectroscopy (AES) technique. While the reflectivity turns out to be highest for a deposition temperature of 150-degrees-C, the thermal stability of the multilayer increases with deposition temperature. The multilayer deposited at 200-degrees-C stands even a 20 min 500-degrees-C baking without considerable changes in the reflectivity behaviour.