Design and performance of capping layers for extreme-ultraviolet multilayer mirrors.
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.
Bajt
Sasa
S
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA. bajt@llnl.gov
Chapman
Henry N
HN
Nguyen
Nhan
N
Alameda
Jennifer
J
Robinson
Jeffrey C
JC
Malinowski
Michael
M
Gullikson
Eric
E
Aquila
Andrew
A
Tarrio
Charles
C
Grantham
Steven
S