FLUORITE, AND OPTICAL SYSTEM AND ALIGNER USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide fluorite in which the transmittance property is hardly deteriorated even when it is repeatedly irradiated with light of high output having a short wavelength for a long period; an optical component made of the same; and an aligner for photolithography using the optical component.

SOLUTION: The fluorite has an internal transmittance to a light having a wavelength of 135 nm of ≥70%. The fluorite contains strontium in a content of 1-600 ppm. An optical system for excimer laser has at least one lens made of the fluorite or the fluorite containing strontium. The aligner for photolithography includes the optical system having at least one lens made of the fluorite and a stage for holding a substrate being exposed. The aligner for photolithography includes the optical system having at least one lens made of the fluorite containing strontium and the stage for holding the substrate being exposed.

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