| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing a large diameter CaF<SB>2</SB>single crystal which is suitable for an optical system for regular optical instruments or photolithography and further, which can be used in an optical system of a stepper for the semiconductor lithography, in which high optical performance is required. SOLUTION: The method of growing the single crystal comprises growing the single crystal while keeping the temperature difference between the axial central part and the outermost peripheral part of a seed crystal at a value of≤6°C, in the same plane perpendicular to the axis of the crystal growth direction of the seed crystal and keeping the temperature at one end (A) in the crystal growth direction of the seed crystal at a temperature (1,380 to 1420°C) at which a CaF<SB>2</SB>raw material starts to melt and the temperature at the other end (B) at a temperature of≤97% of the temperature of (A). COPYRIGHT: (C)2003,JPO
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