APPARATUS FOR PRODUCING CRYSTAL

摘要

PROBLEM TO BE SOLVED: To obtain a crystal production apparatus having a melt-moving means effective for keeping the controllability of a crystal by lifting a seed and a crucible by the same distance to effect the moving of the liquid level of melt in a production apparatus to grow a crystal by lifting a seed. SOLUTION: A liquid level moving process is a process for intentionally moving the liquid level to control the evaporation rate of oxygen, dissolution amount of oxygen and crystal temperature gradient and correct the discrepancy of the liquid level. The apparatus is provided with a crystal growth rate determining part 100, a ratio calculation part 102 to multiply the growth rate of a crystal 10 by the ratio of the increase in the grown length of the crystal 10 to the lowered liquid level of the melt 12 and a liquid level moving rate adding part 104 to add the liquid level moving rate to both of the multiplication result of the ratio calculation part and the crystal growth rate. It is preferably further provided with a liquid level variation detection part 106 to detect the variation of the liquid level of the melt and a speed conversion part 108 to calculate the liquid level moving speed by converting the liquid level variation into the speed. The liquid level is moved while keeping the constant ratio of the increase in the grown length of the crystal to the lowering amount of the liquid level.