METHOD FOR REGENERATING SEED CRYSTAL IN PRODUCTION OF METAL FLUORIDE SINGLE CRYSTAL BY MELT-SOLIDIFICATION METHOD USING SEED CRYSTAL

摘要

PROBLEM TO BE SOLVED: To provide a method for regenerating a seed crystal into a shape suitable for crystal growth in a crystal growth furnace, the seed crystal having a caving center portion at the bottom end compared to the circumference edge caused by troubles in the crystal growth furnace while producing a metal fluoride single crystal by Czochralski method or Kyropoulos method.;SOLUTION: The following operation is repeated on a seed crystal 116 having a caving center portion at the bottom end compared to the circumference edge. The operation comprises: descending the seed crystal 116 while rotating at 10 to 30 rpm so as to immerse the bottom end in a raw material melt 104 heated and held at a temperature higher by 10 to 100°C than the melting point; and elevating the seed crystal 116 within 120 seconds of immersion to bring the crystal into a non-contact state with the raw material melt 104. Thereby, the bottom end of the seed crystal 116 can be regenerated into a flat form. Then the seed crystal having the flat bottom end is used to start growing a single crystal.;COPYRIGHT: (C)2012,JPO&INPIT