23 March 2009 Assumptions and trade-offs of extreme ultraviolet optics contamination modeling
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Extreme ultraviolet (EUV) lithography is one of the most promising candidates for device patterning at the 22 nm halfpitch node. The contamination of extreme ultraviolet optics has consistently been listed among the top challenges for the commercialization of EUV lithography. In a lithography exposure tool under radiation exposure, the two main mechanisms that degrade reflectivity of EUV molybdenum/silicon multilayer optics are carbonization and oxidation. The accumulation of carbon on the mirror surfaces is a consequence of residual hydrocarbons and/or other carbon containing molecules, while oxidation is likely due to water vapor. Theoretical and numerical modeling of EUV optics and mask contamination kinetics can provide valuable insight into reaction mechanisms and help identify favorable conditions that suppress contamination accumulation. However, the complexity of the underlying surface chemistry currently renders obtaining predictive quality challenging. We investigate the validity of different model assumptions and present preliminary numerical results on the dependence of contamination rates on key parameters including the effect of out-of-band radiation.
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V. Jindal, V. Jindal, R. Garg, R. Garg, G. Denbeaux, G. Denbeaux, A. Wüest, A. Wüest, } "Assumptions and trade-offs of extreme ultraviolet optics contamination modeling", Proc. SPIE 7271, Alternative Lithographic Technologies, 72713Q (23 March 2009); doi: 10.1117/12.814188; https://doi.org/10.1117/12.814188

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