PRODUCTION METHOD FOR SAPPHIRE SINGLE CRYSTAL

摘要

PROBLEM TO BE SOLVED: To provide a production method for sapphire single crystal that has a high crystallization rate with respect to a fed raw material.SOLUTION: The production method for a sapphire single crystal by a Czochralski method is provided in which a seed crystal 20 is brought into contact with a material melt 21 in a crucible 12, which is heated and molten by a cylindrical heater 14 arranged facing a side face of an outer surface of the crucible 12 and a disk-shaped heater 13 arranged facing a bottom face of the outer surface of the crucible 12, then the seed crystal 20 and a sapphire single crystal 22 is pulled up while rotating the seed crystal 20. The production method for a sapphire single crystal performs a cylindrical heater lowering step of lowering the cylindrical heater 13 after the seed crystal 20 starts to be pulled up; and/or a disk-shaped heater moving step of elevating the disk-shaped heater 13 toward the bottom face of the outer surface of the crucible 12. The cylindrical heater lowering step and/or the disk-shaped heater moving step is performed after a shoulder part of the sapphire single crystal is formed or when the material melt has a solidification ratio of 50% or higher.SELECTED DRAWING: Figure 1