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Design and Performance of Capping Layers for Extreme-Ulatraviolet Multilayer Mirrors



Sasa Bajt, H N. Chapman, Nhan Nguyen, J Alameda, J C. Robinson, M Malinowski, E Gullikson, Andrew Aquila, Charles Tarrio, Steven Grantham


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 projections optics and has been tested with acclerated 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 equal to} 40 x longer lifetimes thatn Si-capped multilayers, which translates to 3 months to many years, depending on the mirror dose.
Applied Optics
No. 28


capping layers, EUV, extreme ultraviolet lithography, mirrors, multilayer mirrors, optics, oxidation resistance, reflectivity, ruthenium


Bajt, S. , Chapman, H. , Nguyen, N. , Alameda, J. , Robinson, J. , Malinowski, M. , Gullikson, E. , Aquila, A. , Tarrio, C. and Grantham, S. (2003), Design and Performance of Capping Layers for Extreme-Ulatraviolet Multilayer Mirrors, Applied Optics (Accessed April 22, 2024)
Created September 30, 2003, Updated October 12, 2021