Properties of ultra-large CaF2 crystals for the high NA optics

Y. Hatanaka; H. Yanagi; T. Nawata; Y. Inui; T. Mabuchi; K. Yasumura; E. Nishijima; T. Fukuda

doi:10.1117/12.600318

12 May 2005 Properties of ultra-large CaF₂ crystals for the high NA optics

Y. Hatanaka, H. Yanagi, T. Nawata, Y. Inui, T. Mabuchi, K. Yasumura, E. Nishijima, T. Fukuda

Proceedings Volume 5754, Optical Microlithography XVIII; (2005) https://doi.org/10.1117/12.600318
Event: Microlithography 2005, 2005, San Jose, California, United States

Abstract

CaF2(Calcium fluoride) lens materials are required for the most important component of the ArF laser lithography stepper for the reason of its excellent transparency in DUV region and excellent laser durability as compared with quartz. Last year we reported to succeed in growing both <111> and <100> crystals, which had 210m diameter and 150mm length by the Czochralski (CZ) method with high productivity¹). The obtained CaF2 crystal had low stress birefringence by way of the optimized annealing process. Although, for the higher NA system, larger CaF2 single crystals are required for the lens materials having the high quality and high productivity. To meet the above mentioned demands, we made efforts to produce and succeeded the first in the world ultra-large (φ300mm over) and high quality CaF2 single crystal by the CZ method with high productivity. The crystal had very low stress birefringence, good transparency in DUV region and good homogeneity. It was also easy to control the orientation of the crystal by the selection of seed crystal.

Citation Download Citation

Y. Hatanaka, H. Yanagi, T. Nawata, Y. Inui, T. Mabuchi, K. Yasumura, E. Nishijima, and T. Fukuda "Properties of ultra-large CaF₂ crystals for the high NA optics", Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005); https://doi.org/10.1117/12.600318

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