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17 April 2014 Contribution of EUV resist components to the non-cleanable contaminations
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The suppression of outgassing from extreme ultraviolet (EUV) resist needs to be addressed for realizing EUV lithography (EUVL) because outgassing is likely the main contributor to the contamination of mirror optics in EUV scanners, which results in reflectivity loss. Resist outgassing causes two types of contamination: cleanable contamination, involving hydrocarbon contaminants, and noncleanable contamination, involving noncarbon components. The relation of cleanable contamination between EUV- and electron beam (EB)-based evaluations is linear. However, the relation of noncleanable contamination is not clear. In this study, we investigated the contribution of EUV resist components to noncleanable contamination using different photoacid generator components. The cleanability of noncleanable elements (sulfur, iodine, chlorine, and bromine) in contamination films was measured and compared for the EUV- and EB-based outgas testers. The result suggested that the chlorine and bromine contaminants were completely removed after cleaning. On the other hand, sulfur and iodine remained even after cleaning. This suggested that the careful use of iodine in resist materials is necessary due to its high photoabsorption and low cleanability. In addition, the cleaning rate and noncleanability of contaminants in the EUV-based test were larger than in the EB-based test. This suggests that the contamination film in the EUV-based test is more porous than that in the EB-based test.
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Eishi Shiobara, Toshiya Takahashi, Norihiko Sugie, Yukiko Kikuchi, Isamu Takagi, Kazuhiro Katayama, Hiroyuki Tanaka, Soichi Inoue, Takeo Watanabe, Tetsuro Harada, and Hiroo Kinoshita "Contribution of EUV resist components to the non-cleanable contaminations", Proc. SPIE 9048, Extreme Ultraviolet (EUV) Lithography V, 904819 (17 April 2014);

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