<title>Al/Ir multilayers for high relectance in the extreme ultraviolet longward of 50 nm</title>

Abstract

Extreme UV reflectance measurements of multilayer coatings based on IR and non-oxidized Al films are presented. Two kinds of multilayer coatings were prepared: bilayers of a thin non- oxidized Al film over an IR film, and multilayers IR/Al/IR and IR/Al/IR/Al/IR. The bilayers were aimed at enhancing pure Al reflectance below Al plasma wavelength (approximately 83 nm). Multilayers with IR as the outermost film were designed for highest reflectance at 53.6 nm. We deposited IR films by evaporation on heated and unheated substrates by means of an electron gun, and Al films by evaporation on room temperature substrates from a thermal source. Multilayer coatings were prepared under UHV conditions and their reflectance was measured in situ. The short-term multilayer aging was also investigated.