| 摘要 |
PURPOSE:To prepare high-quality single crystal in high yield, by penetrating electrically-conductive rods into a given depth from melt surface, detecting the position of melt surface, taking it out to the outside as a signal, controlling each sequence of pulling process depending upon the signal. CONSTITUTION:A sintered raw material such as LiTaO3 is put in the crucible 1, melted by a heater, and the electrically-conductive rods 2 and 3 are penetrated into a given depth of the melt. The seed crystal 4 in the X axis direction is brought into contact with the melt and the crystal 4 is pulled up while being rotated. When the diameter of the crystal 4 is grown, the melt surface is lowered, and the tip of the electrically-conductive rod 2 is released from the melt surface, the relay circuit 5 is started and the work coil 9 starts to sink. In this state, the crystal is further pulled up and the melt surface is sunk, so the tip of the electrically-conductive rod 3 is released from the melt surface and the relay circuit 6 is operated. Consequently, the pulling motor 7 is exchanged to the quick sending motor 8, the crystal 4 is separated from the melt surface and the pulling is finished. |
