Abstract

$\mathrm{Cr}/\mathrm{Sc}$ multilayer mirrors, synthesized by ion-assisted magnetron sputter deposition, are proved to have a high near-normal reflectivity of $R=14.5\%$ at a grazing angle of 87.5° measured at the wavelength $\lambda =3.11 \mathrm{nm}$, which is an improvement of more than 31% compared with previously published results. Elastic recoil detection analyses show that the mirrors contained as much as 15 at. % of N and traces of C and O. Soft x-ray reflectivity simulations reveal interface widths of $\sigma =0.34 \mathrm{nm}$ and an exceptionally small layer thickness drift of $\sim 1.6\times {10}^{-5} \mathrm{nm}/\mathrm{multilayer}$ period throughout the stack. Simulations show that a reflectivity of $R=25.6\%$ is attainable if impurities and layer thickness drift can be eliminated. The abrupt interfaces are achieved with ion assistance with a low ion energy of 24 eV and high ion-to-metal flux ratios of 7.1 and 23.1 during Cr and Sc sputter deposition, respectively. In addition, a near-normal incidence reflectivity of 5.5% for the C VI emission line $\left(\lambda =3.374 \mathrm{nm}\right)$ from a laser plasma source was verified.

© 2003 Optical Society of America

Impact of B₄C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

Naureen Ghafoor, Fredrik Eriksson, Andrew Aquila, Eric Gullikson, Franz Schäfers, Grzegorz Greczynski, and Jens Birch
Opt. Express 25(15) 18274-18287 (2017)

Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics

Fredrik Eriksson, Naureen Ghafoor, Franz Schäfers, Eric M. Gullikson, Samir Aouadi, Susanne Rohde, Lars Hultman, and Jens Birch
Appl. Opt. 47(23) 4196-4204 (2008)

Interface engineered ultrashort period Cr-Ti multilayers as high reflectance mirrors and polarizers for soft x rays of lambda = 2.74 nm wavelength

Naureen Ghafoor, Per O. Å. Persson, Jens Birch, Fredrik Eriksson, and Franz Schäfers
Appl. Opt. 45(1) 137-143 (2006)

Normal-incidence reflectance of optimized W/B₄C x-ray multilayers in the range 1.4 nm < λ < 2.4 nm

David L. Windt, Eric M. Gullikson, and Christopher C. Walton
Opt. Lett. 27(24) 2212-2214 (2002)

Ion polished Cr/Sc attosecond multilayer mirrors for high water window reflectivity

Alexander Guggenmos, Stefan Radünz, Roman Rauhut, Michael Hofstetter, Sriram Venkatesan, Angela Wochnik, Eric M. Gullikson, Stefan Fischer, Bert Nickel, Christina Scheu, and Ulf Kleineberg
Opt. Express 22(22) 26526-26536 (2014)