| 摘要 |
In a conventional method of pulling a large-sized single crystal, an expanded portion and a contracted portion are formed on the lower side of a neck, and the contracted portion is engaged with the single crystal, which is then pulled. During the formation of the contracted portion, the diameter thereof is reduced sharply in a usual case. Even when the diameter of this portion is controlled by using an optical measuring means, a fusion ring on the contracted portion which is hidden behind the expanded portion cannot be observed, so that it is difficult to control the diameter of the crystal. A single crystal pulling apparatus used in this method has a complicated structure and is liable to get out of order at high temperature. According to the present invention, a contracted portion is formed under the condition where the diameter thereof can be measured constantly with an optical measuring means. This method uses a single crystal pulling apparatus which is provided with a pressing means which constitutes a single crystal retaining means, and which is adapted to move a locking portion engaged with a contracted portion of the crystal from a standby position to a contracted portion engaging position. |
