| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for reducing oxygen and carbon components contained in high purity fluorides, such as calcium fluoride, barium fluoride used as a material for a stepper lens of an exposure device for photolithography, or the like, or in rare earth fluorides such as ytterbium fluoride, cerium fluoride, used as a material for an optical fiber, a coating material, or the like. SOLUTION: The oxygen and carbon components contained in the high purity fluorides can be reduced by subjecting the fluorides to a treatment using gaseous fluorine. |
