Abstract: A method of controlling the diameter of a silicon single crystal. In the course of manufacturing a silicon single crystal by pulling the silicon single crystal while rotating it relative to a crucible, a comparison between a measured diameter value of the pulled single crystal measured by optical means and a desired diameter value is made to determine a deviation so that the resulting deviation is subjected to an incomplete differential PID processing or the Smith method processing to calculate a pull rate and the pull rate is applied to a motor controller of a crystal pulling apparatus thereby performing the diameter control of the pulled single crystal through the manipulation of the pull rate.

Abstract: A method of measuring the diameter of a silicon single crystal. At intervals of a given rotational period of a pulled single crystal being pulled by the CZ method, optical means samples the luminance distribution of a fusion ring to obtain measured diameter values of the pulled single crystal so that the measured diameter values are processed by a low-pass filter to generate filter output values converted to time series diameter data and the filter output values are subjected to moving averaging to calculate a diameter value.

Abstract: A method of controlling the diameter of a silicon single crystal. In the course of manufacturing a silicon single crystal by pulling the silicon single crystal while rotating it relative to a crucible, a comparison between a measured diameter value of the pulled single crystal measured by optical means and a desired diameter value is made to determine a deviation so that the resulting deviation is subjected to an incomplete differential PID processing or the Smith method processing to calculate a pull rate and the pull rate is applied to a motor controller of a crystal pulling apparatus thereby performing the diameter control of the pulled single crystal through the manipulation of the pull rate.