Experimental test chamber design for optics exposure testing and debris characterization of a xenon discharge produced plasma source for extreme ultraviolet lithography

A commercial EUV light source is currently used in the MS-13 EUV Micro Exposure Tool (MET) produced by Exitech Ltd. The source uses a xenon z-pinch discharge to produce 13.5 nm light intended for use in extreme ultraviolet lithography (EUVL). During operation, an erosive flux of particles is ejected from the pinch plasma, contributing to limitations in the lifetime of nearby collector optics. A diagnostic chamber is presented that permits characterization of the debris fields present, exposure of optical samples, and evaluation of debris mitigation techniques. Available diagnostics include a Faraday cup, a spherical sector energy analyzer (ESA), and a EUV photodiode. This paper details the chamber design and initial results of source characterization. Faraday cup analysis shows that the maximum theoretical ion energy is 53 keV, ESA measurements show the presence of Xe+, Xe2(+), At+, W+, and Mo+ ions, and microanalysis of exposed mirror samples is used to show the erosive effects of plasma exposure. (c) 2005 Elsevier BN. All rights reserved.