MO0.5SI0.5 SI MULTILAYER SOFT-X-RAY MIRRORS, HIGH THERMAL-STABILITY, AND NORMAL INCIDENCE REFLECTIVITY/

Multilayer soft x-ray mirrors with an absorber consisting of the mixtu re Mo0.5Si0.5 have been fabricated by electron-beam evaporation in UHV . This has been done to get soft x-ray normal incidence mirrors for 80 -100 eV photon energy with enhanced thermal stability and still high r eflectivity. The thermal stability is studied by baking them at temper atures between 600 and 950-degrees-C. The results were compared with m ultilayers of pure Mo and Si, which were also fabricated by electron-b eam evaporation. After each baking step the x-ray mirrors are characte rized by small angle Cu(Kalpha) x-ray diffraction. The reflectivity of the first-order Bragg peak is nearly constant up to 20 min baking at 900-degrees-C. Further we present the normal incidence soft x-ray refl ectivity for wavelengths between 12 and 18 nm of a Mo0.5Si0.5/Si mirro r with 12 double layers (N = 12) and of a Mo0.5Si0.5/Si mirror as depo sited with 33 double layers (N = 33). With the latter a reflectivity o f 46% is achieved.