Most of the currently used reflective coatings for EUV and X-ray mirrors are periodic nanometer multilayers. Depending on the number of periods and the absorption in the multilayer stack a certain band width of the incoming radiation can be reflected. In order to increase the integral reflectance or to accept larger ranges of incidence angles, non-periodic multilayers are needed. With the transition from periodic to non-periodic multilayers new challenges arise for the deposition process. Since the reflectance spectra are sensitive to every single layer thickness a precise coating control and an exact knowledge of the interface reactions are required. Furthermore substrate roughness influences the reflectance spectra. With an advanced coating process using additional ion bombardment during thin film growth the integrated reflectance of broadband mirrors can be conserved even for an initial substrate roughness of about 0.7 nm rms.

Date Published: 17 September 2014
PDF: 10 pages
Proc. SPIE 9207, Advances in X-Ray/EUV Optics and Components IX, 920707 (17 September 2014); doi: 10.1117/12.2062193

Published in SPIE Proceedings Vol. 9207:
Advances in X-Ray/EUV Optics and Components IX
Christian Morawe; Ali M. Khounsary; Shunji Goto, Editor(s)