23 April 2008 High refractive index materials design for the next generation ArF immersion lithography
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High-refractive-index fluids (HIFs) are being considered to replace water as the immersion fluid in next generation 193nm immersion scanner. We have demonstrated the attractive optical properties for our HIF candidates, HIL-001, HIL-203 and HIL-204. Especially, HIL-203 and HIL-204 have higher transmittance compared to water. In this paper, we describe our latest results on the comparative evaluations including photo-degradation behavior and lens contamination phenomenon in a flow system. For laser induced fluid degradation behavior, it was shown the higher initial transmittance resulted in the higher laser durability. However, the complicated phenomenon was observed for the lens contamination test. That is, HIL-204 with higher initial transmittance showed higher lens contamination rate than HIL-203. From several analyses, the complicated behaviors among HILs were speculated to be caused by the different nature of photo-degraded impurities. In order to control the fluid transmittance change and suppress the lens contamination during exposure, the refining process was definitely necessary for HIL reuse system. Based on the refining mechanism and the refining material design, we have developed an appropriate refinement unit named Refine B. This approach provided us with the result that Refine B could control the change of fluid transmittance and suppress the lens contamination rate.
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Taiichi Furukawa, Taiichi Furukawa, Takanori Kishida, Takanori Kishida, Kyouyuu Yasuda, Kyouyuu Yasuda, Tsutomu Shimokawa, Tsutomu Shimokawa, Zhi Liu, Zhi Liu, Mark Slezak, Mark Slezak, Katsuhiko Hieda, Katsuhiko Hieda, } "High refractive index materials design for the next generation ArF immersion lithography", Proc. SPIE 6924, Optical Microlithography XXI, 692412 (23 April 2008); doi: 10.1117/12.771122; https://doi.org/10.1117/12.771122

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