Highly reflective Ru/Y multilayer mirrors for the spectral range of 9-11 nm

The results of the investigation of the reflective characteristics of multilayer mirrors based on Ru/Y are presented. Reflection coefficients at the level of 38.5% at an operating wavelength of 9.4 nm. It is shown that the deposition of B-4 C barrier layers onto Y layers makes it possible to significantly increase the reflection coefficient compared to structures without barrier layers. A reflectance of 54% was obtained for mirrors optimized for 11.4 nm, which is close to the theoretical limit for these materials. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement