Affiliations: Laboratoires d'Electronique Philips (LEP), 22 Avenue Descartes, BP15, 94453 Limeil-Brevannes Cedex, France | Phys. Tech. Bundesanstalt, C/O Bessy, Lentze Allee 100, D1000 Berlin 33, FRG | Laboratoire de Chimie Physique, Université Paris VI, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France | Institut d'Astrophysique Spatiale, BP 10, 91371 Verrières Le Buisson Cedex, France | Center for Solid State Science and Department of Physics, Arizona State University, Tempe, Arizona 85287
Abstract: W/Mg2Si multilayers for soft x-ray optics above the MgKα and MgLα lines have been deposited by RF sputtering. Their structural characteristics have been deduced from in situ kinetic ellipsometry, ex situ grazing x-ray reflection measurements, and high-resolution electron microscopy. Their soft x-ray performances have been measured by synchrotron radiation around the MgKα and MgLα lines and related to the structural characteristics. For short wavelengths, first Bragg peak reflectivities as high as 31% have been measured for multilayers with double period equal to 84 Å. For samples with smaller layer thicknesses, these performances decrease due to finite interdiffusion at the interfaces. Nevertheless, well-defined Bragg peaks are observed even when the double period is as low as 44 Å. Near the MgLα line, more than 20% reflectivity at the first Bragg peak has been measured at normal incidence. At the same wavelength the selectivity is two times higher than that of conventional systems such as Mo/Si.
