Patent ID: 8764900
Filing Date: 2014-07-01
Classification: C30B,Y10T

Abstract:
1. A method for producing single crystals according to a Czochralski method, at least, using an apparatus for producing single crystals comprising a chamber that can be divided into a plurality of chambers, the method comprising: a first step of calculating a quantity of heat removed from at least one of a plurality of divided chambers by cooling with a circulating coolant and/or a proportion of the quantity of removed heat; a second step of investigating a relationship between a variation in the quantity of removed heat from the chamber and/or the proportion of the quantity of removed heat and a crystal quality associated with aggregation defects of the resulting single crystal; a third step of determining a relationship between a quantity of removed heat from a chamber and/or a proportion of the quantity of removed heat and a single-crystal pulling rate that produces a desired crystal quality associated with aggregation defects, with respect to a target chamber having a correlation between a variation in the quantity of removed heat from the chamber and/or the proportion of the quantity of removed heat and a change in the crystal quality associated with aggregation defects of the resulting single crystal; a fourth step of correcting a set value of single-crystal pulling rate so as to give a pulling rate that produces a desired crystal quality associated with aggregation defects, based on the quantity of removed heat from the target chamber and/or the proportion of the quantity of removed heat; and a fifth step of pulling a single crystal from a crucible at the corrected single-crystal pulling rate, wherein the quantity of heat removed from the at least one of the plurality of divided chambers by cooling with the circulating coolant, and/or the proportion of the quantity of removed heat, is calculated from measured values of an inlet temperature, an outlet temperature and a circulating coolant flow rate of the circulating coolant in a circulating coolant passage.