IN-SITU REFLECTANCE MEASUREMENTS OF SOFT-X-RAY EXTREME-ULTRAVIOLET MOY MULTILAYER MIRRORS/

With a new ultrahigh-vacuum deposition/reflectometer system, Mo/Y mult ilayer mirrors were deposited by dc-magnetron sputtering and character ized in situ with synchrotron radiation. The Mo/Y multilayer mirrors, measured before exposure to air, had near-normal-incidence reflectance s as high as 46% at wavelengths near 11.4 nm. After several days of ex posure these samples typically had a relative reflectance loss of simi lar to 10% as a result of oxidation of the top Mo layer. The best Mo/Y multilayers were fabricated with base pressures below the low 10(-9) Torr range and after a bakeout to reduce water vapor in the chamber.