Method of automatic control of growing neck portion of a single crystal by the CZ method

A method of automatic control of growing a single crystal neck portion between a seed crystal and a corn portion of the single crystal by the CZ method, comprising the steps of:

• (110, 112) pulling up the seed crystal (30) from the lowest initial point with a constant speed for a first set period of time, less than the total time, before measuring crystal diameter to grow the single crystal (32), said crystal contacting with the surface (22S) of a melt (22) contained in a crucible (16);
• (113) measuring the diameter of the lower end of said single crystal after said period has elapsed;
• (114) modifying an electric power supplied to a heater (18) for heating said melt based on the difference between the measured diameter and a reference value;
• waiting a period of time without pulling up said crystal (116) and alternately repeated steps of:
• maintaining constant, for a second set period of time, an electric power supplied to a heater for heating a melt contained in a crucible;
• controlling a pulling up speed of the single crystal growing from said melt such that a diameter of the lower end of the single crystal will approach a reference value during said period;
• measuring said speed repeatedly during said period (118-124);
• and
• modifying said power supply based on the difference between the mean value of said speed and a reference value after said period (126-130).