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

Published

October 1, 2003

Author(s)

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

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 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.

Citation

Applied Optics

Volume

42

Issue

No. 28

Pub Type

Journals

Keywords

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

Citation

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 October 26, 2025)