Manufacturing methods and calcium fluoride crystals, as well as exposure apparatus of fluoride crystal

摘要

PPROBLEM TO BE SOLVED: To provide a production method which enables production of a fluoride crystal which yields a sufficient resolving power when exposed to an FSB2/SBlaser. PSOLUTION: The production method of the fluoride crystal comprises a crystallization step wherein an ingot is obtained through crystal growth. Before the crystallization step, a fluorinating agent comprising a metal fluoride is added to a raw material for the fluoride, and the raw material is heat-melted. Here, the concentrations of Ce, Cr, K, Fe, Mn, Na, Si and Y contained in the fluorinating agent are each adjusted to 10 ppm before use. PCOPYRIGHT: (C)2005,JPO&NCIPI