| 摘要 |
PROBLEM TO BE SOLVED: To keep the productivity of an ingot at a high level and remove impurity elements in high efficiency in the unidirectional solidification of molten silicon poured into a mold by measuring the freezing interface position and controlling the heating and cooling of the silicon in such a manner as to make the moving speed of the freezing interface determined by the measured result coincide with the target value. SOLUTION: Molten silicon 9 poured into a mold 1 is solidified by unidirectionally moving the freezing interface. In this process, the position of the freezing interface is measured and the moving speed of the interface is determined based on the measured result. The surface of the silicon 9 is heated 2 and the bottom is cooled 3 in such a manner as to make the freezing speed coincide with the target value. For example, thermometers 4 are placed on the wall of the mold 1 in plural stages, the measured results are inputted into a freezing speed controlling means 5 to obtain the freezing speed, the measured speed is compared with a target value and the heating and the cooling are carried out according to the output from the comparison means. The position of the freezing interface can be measured also by an ultrasonic depth sensor placed above the mold 1. |
