Method and apparatus for controlling the diameter of a silicon single crystal

摘要

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. An apparatus for controlling the diameter of a silicon single crystal includes input means for receiving a measured diameter value of a pulled single crystal measured by optical means, incomplete differential PID computing means for making a comparison between a measured diameter value of the pulled single crystal and a desired diameter value a plurality of times at intervals of a unit rotational period to calculate a pull rate, and output means for applying the pull rate to a motor controller of a crystal pulling apparatus.