Patent attributes
By pulling up an ingot in consideration of deformation of a crucible, generation of the defective ingot is prevented and a plurality of ingots having equivalent quality with the first ingot are pulled up in a multiple pull-up. Firstly, a deformation amount of a crucible for experiment (34) upon melting a silicon raw material and a history of supply power to a heater for experiment (38) are measured to calculate deformation tendency of a crucible for mass production (14). Next, the size of the crucible for mass production is measured, the silicon raw material of the amount equivalent to the amount supplied to the crucible for experiment is melted with a heater for mass production (18), and an initial crucible external position with a predetermined gap (X) is measured before initiating pull-up. Moreover, the deformation amount of the crucible for mass production upon melting the silicon raw material is predicted based on such as a relation between the deformation tendency of the crucible for experiment and the initial crucible external position, an initial crucible internal position when the predetermined gap is provided is predicted based on the deformation amount of the crucible for mass production, and an optimal pulling-up speed of the ingot is derived from predictive calculation to initiate the pull-up of the ingot at the optimal pulling-up speed.
