A design strategy for the fabrication broadband grazing incidence mirrors in the wavelength range of 0.8–18nm is proposed. Instead of high-density materials, we propose a bilayer coating consisting of the high-density material most suitable for the task coated with a thin film of low-density material. In the wavelength range of 4–18nm, an increase of the reflection coefficients of such coatings by 10–20% compared with the single high-density layers traditionally used is theoretically expected. We also present an experimental demonstration of such advantageous properties based on a Cr-C bilayer film.

By the example of three aperiodic multilayer Mo/Si mirrors (AMM) for the wavelength ranges 17-21 nm, 24-29 nm, and 28-33 nm we have studied numerically the effect of the linearly determinisctic and random fluctuations of the film thickness and the interlayer roughness on the spectral dependences of the reflection coefficient. The simulation results are used to solve the inverse problem of reconstructing the interlayer roughness and the thickness of individual films from the measured dependences of the extreme UV radiation reflection coefficients. It is shown that the `asymmetry' of the boundaries affects the magnitude and slope of the reflection coefficient plateau. Random fluctuations of the film thickness with the variance of 1%-2% weakly influence the reflection characteristics of AMMs and allow reliable reconstruction of the thickness of individual films. The fluctuations with the variance 8%-10% allow the estimation of individual thicknesses, but the reflection curve in this case strongly differs from the desirable one. Larger fluctuations do not allow the reconstruction of the AMM structure. The basic criteria for high-quality AMM synthesis are formulated.

The problems of creating multilayer structures for the soft X-ray range are discussed. The search for an absorbing material for multilayer mirrors and phase shifters based on scandium for the water-window spectral range (wavelength of 2.3–4 nm) is performed. A comparison of the reflection characteristics of normal-incidence mirrors and the properties of phase shifters during numerical simulation of different pairs of materials shows the possibility of using cobalt as an absorbent in a pair with scandium.

В работе обсуждаются проблемы создания многослойных структур для мягкого рентгеновского диапазона. Проведен поиск парного скандию материала для структур на основе скандия для спектральной области “водного окна” (длины волн 2.3–4 нм). Сравнение полученных в ходе численного моделирования отражательных характеристик зеркал нормального падения и фазовращательных свойств пленок для разных пар материалов показало перспективность использования кобальта в качестве рассеивающего материала в паре со скандием.