title: Design and performance of capping layers for extreme-ultraviolet multilayer mirrors.
abstract: Multilayer lifetime has emerged as one of the major issues for the commercialization of extreme-ultraviolet lithography (EUVL). We describe the performance of an oxidation-resistant capping layer of Ru atop multilayers that results in a reflectivity above 69% at 13.2 nm, which is suitable for EUVL projection optics and has been tested with accelerated electron-beam and extreme-ultraviolet (EUV) light in a water-vapor environment. Based on accelerated exposure results, we calculated multilayer lifetimes for all reflective mirrors in a typical commercial EUVL tool and concluded that Ru-capped multilayers have approximately 40x longer lifetimes than Si-capped multilayers, which translates to 3 months to many years, depending on the mirror dose.
authors.affiliation: Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA. bajt@llnl.gov
authors.forename: Sasa
authors.initials: S
authors.lastname: Bajt
authors.forename: Henry N
authors.initials: HN
authors.lastname: Chapman
authors.forename: Nhan
authors.initials: N
authors.lastname: Nguyen
authors.forename: Jennifer
authors.initials: J
authors.lastname: Alameda
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Robinson
authors.forename: Michael
authors.initials: M
authors.lastname: Malinowski
authors.forename: Eric
authors.initials: E
authors.lastname: Gullikson
authors.forename: Andrew
authors.initials: A
authors.lastname: Aquila
authors.forename: Charles
authors.initials: C
authors.lastname: Tarrio
authors.forename: Steven
authors.initials: S
authors.lastname: Grantham