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

A device for holding a feed rod in a pulling installation for zone melting, the device comprising:

• an upper part, the upper part comprising:
• a connecting element, which serves for the fitting into the pulling installation;
• and
• a radial alignment element configured to radial align the upper part in the pulling installation:
• a lower part, the lower part comprising three gripping arms, the three gripping arms being formed in such a way that one end fits into a groove in the lateral surface of the feed rod, and another end is attached rotatably;
• and
• three length-adjustable spacer elements attached to the upper part in such a way that the length-adjustable spacer elements are configured to exert force respectively onto a gripping arm, of the gripping arms,
• wherein the upper part and the lower part are connected by a bearing, the bearing having the effect that a connection is radially with a form fit in a self-centering and detachable manner with respect to one another.

A method for pulling a monocrystalline rod from silicon in a pulling installation for zone melting, including the following steps

• providing a feed rod of silicon, which at one end comprises a groove in the lateral surface;
• attaching a lower part of a device for holding the feed rode, the lower part comprising three gripping arms, formed in such a way that one end fits into the groove of the feed rod and another end is attached rotatably to 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, so that the upper part and the lower part are connected to one another by a 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 attached to the upper part in such a way that they are configured to exert force respectively onto a gripping arm:
• 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.