| 摘要 |
PURPOSE:To obtain a single crystal which is uniform in diameter and is free from ruggedness on a surrace easily with simple handling by detecting the diameter of the single crystal under growing directly from the efficiency applied to a single crystal pulling mechanism and the rotating speed resulted therefrom and controlling the diameter. CONSTITUTION:A controller 14 for diameter is inputted with respective sets of data for the rotating speed of the single crystal under growing applied from a rotating speed detector 10, the torque generated in a motor 9 from a torque setter 11, and the temp. of the melt 4 from a temp. detector 13, determines density and a coefft. of kinematic viscosity from the temp. of a melt 4, calculates the radius of the single crystal 2 under growing from these rotating speed, torque, density and coefft. of kinematic viscosity, compares the same with the diameter applied from a setter 12 for time to diameter programs and increases or decreases the output of an oscillator 8 in such a way that both coincide. Since the detection of the diameter of the crystal 2 under growing is carried out virtually in real time by maintaining accuracy, the single crystal of a good condition having a prescribed diameter size and having virtually no ruggedness on the surface of a circular columnar ingot is obtained. |
