Device and method for producing a monocrystalline silicon rod in a zone-melting pulling system

A method for pulling a monocrystalline rod from silicon in a pulling installation for zone melting, the method comprising:

• providing a feed rod of silicon, which at one end comprises a groove in a lateral surface;
• attaching a lower part of a device to the feed rod, the lower part comprising three gripping arms, each of the gripping arms being formed in such a way that one end fits into the groove of the feed rod and another end is attached rotatably to a central body of the lower part,
• suspending the lower part together with the feed rod on an upper part of the device, the upper part comprising:
• a connecting element, which is connected to a pulling shaft of the pulling installation;
• a bearing configured to support the lower part so that, while the lower part is attached to the upper part, the upper part and the lower part are connected to one another by the bearing which has the effect that the connection is radially with a form fit and in a self-centering manner;
• a radial alignment element;
• and
• three length-adjustable spacer elements arranged in the upper part in such a way that the length-adjustable spacer elements are configured to exert force respectively onto a corresponding gripping arm of the gripping arms while the lower part is suspended from the upper part;
• moving the radial alignment element so that an axis of rotation of the feed rod at the one end at which the groove is located coincides with an axis of rotation of the pulling shaft;
• setting the length-adjustable spacer elements so that the axis of rotation of the feed rod at an end opposite from the groove coincides with the axis of rotation of the pulling shaft;
• pulling a conical part of the monocrystalline rod;
• and
• pulling a cylindrical part of the monocrystalline rod.