Patent ID: 8216371

Claim:
A single crystal manufacturing apparatus according to the Czochralski method, comprising: multiple heaters for applying heat to a crucible; an elevating/lowering device which pulls up a crystal from said crucible; a temperature measurement device which measures an applied heat temperature, generated by heat applied by said heaters, at a predetermined site of said single crystal manufacturing apparatus; a diameter measurement device which measures the diameter of said crystal; a speed measurement device which measures the pulling up speed of said elevating/lowering device; and a control device configured to set a diameter set value, a speed set value, a variable power ratio temperature set value, and a power ratio set value; configured to input the measured values from said temperature measurement device, said diameter measurement device, and said speed measurement device; configured to control said pulling up speed by said elevating/lowering device and the electrical power of said multiple heaters on the basis of the values measured by said temperature measurement device, said diameter measurement device, and said speed measurement device, and of said diameter set value, said speed set value, and said variable power ratio temperature set value; and configured to make the power ratio of said multiple heaters agree with said power ratio set value; wherein: said power ratio set value changes according to the state of progression of the crystal pulling up process; said variable power ratio temperature set value changes along with the change of said power ratio set value, so as to become a temperature value which corresponds to the current value of said power ratio set value, said control device is configured to set said variable power ratio temperature set value so as to compensate for a change of the measured value of said applied heat temperature which occurs due to change of said power ratio set value, and said control device is configured to calculate said power ratio set value based on a target oxygen density and information in which the relationship between a current oxygen density and a current power ratio for attaining the oxygen density is determined.