Patent ID: 10066313

Abstract:
After melting raw materials, a distance between a raw material melt surface and a heat-shielding member disposed so as to face to the melt surface is adjusted based on temporal changes in chamber inside conditions, such as the heater temperature at the time of completion of the seed crystal equilibration operation carried out after completion of the raw material melting procedure and/or lag time required for completion of the seed crystal equilibration operation following completion of the raw material melting procedure. As a result, single crystals can be produced efficiently and in high yield, and further, by controlling the crystal interior temperature gradient by modifying the distance between the melt surface and the heat-shielding member, it becomes possible to control the ratio V/G (V:pulling speed, G:crystal interior temperature gradient) to thereby produce single crystals free of crystal defects such as COPs and/or dislocation clusters.