Performances of large multilayer mirrors for the 0.5–1.5 nm range

6‐in.‐diam multilayer mirrors were fabricated for a double mirror monochromator designed to select photon energies between 830 and 1240 eV (0.5–1.5 nm). Coatings with 50 and 40 Mo/C bilayers with a bilayer d spacing of 4.1 and 4.6 nm, respectively, and a division parameter of Γ=0.44, were deposited by the triode sputtering method on 6‐in.‐diam silicon with 5% d uniformity. Similar coatings were also deposited on 2 in. silicon wafers. Peak reflectivity and integrated reflectivities were measured at several wavelengths between 0.5 and 1.5 nm using monochromatized synchrotron radiation. Measurements were performed along a 4 in. diameter for the large area coatings. The resolving power as measured in the center of the six inch mirrors was found to be 41 and 46 at 826 and 1240 eV, respectively, which compares well with the corresponding theoretical values of 43 and 40. The performance of a matched pair of multilayer mirrors with the smaller areas in the double mirror configuration was experimentally investigated as well. Reflectivity values for the two mirror configuration scheme were calculated from the experimental data for the individual mirrors. Possible applications of such monochromator in lithography research are briefly described.