Crystal Growing Systems Gmbh

Crystal Growing System Gmbh

Pva Tepla Ag

Andreas Mühe

Burkhard Altekrüger

Axel Vonhoff

The invention relates to the production of a cable rotating head, which is devoid of an abrasion ring, for a Czochralski-crystal drawing system which is used to drive a drawing cord in an azimuthal and vertical manner and the nucleus of a crystal is fixed therein. According to the invention, the cord rotating head comprises a cord winding mechanism which can be supported by a vertical hollow shaft, through which the drawing cord is suspended in the crystal drawing system, and the cord rotating head is rotationally mounted about the axis thereof and can be offset by a rotation motor, which is secured to the crystal drawing system, together with the cord winding mechanism and the drawing cord in a rotational movement, and said vertical hollow shaft is surrounded in a coaxial manner by a double toothed gear which is rotationally mounted opposite to the hollow shaft and can be driven by a drawing motor which is secured to the crystal drawing system. The double toothed gear can be driven by a gear of the cord winding mechanism, such that the mechanical drive energy of the drawing motor, which is secured in a stationary manner to the crystal drawing system, can be transferred to the cord winding mechanism which rotates in relation to the crystal drawing system.

Cord rotating head for a crystal drawing system

This invention is based on the problem of achieving the most planar possible phase boundary extending in the horizontal direction between the still molten material and the material that has already crystallized out in a vertical Bridgman crystal-growing furnace or vertical gradient freeze crystal-growing furnace for crystallizing out the semiconductor melt and doing so at a low cost. Therefore, jacket heaters are provided coaxially with the furnace core containing the crucible and measurement devices for determining radial temperature differences in the space between the jacket heaters and the crucible, whereby the heat output of the jacket heaters is adjusted so that the measured temperature differences become zero. Thus, at least in the planes in which the measurement devices are located, radial heat transport is prevented and a phase boundary that is not curved is implemented.

Crystal-growing furnace, in particular a vertical Bridgman crystal-growing furnace or a vertical gradient freeze crystal-growing furnace having a jacket heater and a method of regulating the heat output of the jacket heater

The invention relates to producing a melt that is as homogeneous as possible, to which fresh material in the form of granulate is continuously supplied. Since the granulate is cooler than the melt, heat sinks form that are especially pronounced when the granulate forms clumps in the melt. Therefore, the invention relates to a means for distributing the granulate. In one aspect, the means are inductors arranged outside the melting crucible that generate an alternating magnetic field in the melt. In this way, electrical currents are induced there that, in turn, cause the material flows. In one aspect, the inductors are arranged and controlled in such a way that a rapid distribution of the granulate is effected and thus its rapid melting. In this way, good homogeneity is achieved, especially in the center of the melt where the removal of the melted material also occurs.

Melting crucible

The invention presented here relates to a crystal growing equipment. It is equipped in general with a resistance heater for heating a melt () as well as with field coils, which generate alternating magnetic field in a crucible, with which flows can be induced in the melt (). The invention is so designed that the resistance heaters are also devised to function as the field coils, that is, they are built of a hollow cylindrical body (), in which, by means of a surrounding slit () which winds around it, a spiral-shaped single layer current path is formed. This has the advantage that the current needed for the electrical heating in the equipment is also used for the generation of the magnetic field. Thus, neither separate field coils nor a separate current supply is necessary. Further, the resistance heater, which serves as the field coil arranged as a coil array, is high temperature resistant and surrounds the immediate hot core zone of the equipment and thus the region of the melt. Thus the volume, in which the magnetic field must be generated, is minimized. Further, the alternating magnetic field does not need to penetrate through the wall of the vessel of the crystal growing equipment, hence the vessel can be designed as a steel boiler in conventional manner.

Crystal growing equipment

A process for calibrating the temperature control unit of a vertical gradient freeze crystal growth oven, instead of the fused material a test body () is used in the oven () that does not melt at the oven temperature, that has a heat conductivity comparable to the fused material and a central bore (). After turning on the resistance heaters () of the oven () the temperature at the level of the individual control temperature indicators () of the oven () is measured via a reference temperature indicator () that can be fully inserted into the bore () and subsequently the output of the respective resistance heaters () is set to a desired temperature value. After removing the test body () and the reference temperature indicator (), the oven () is operated according to the control temperature indicators () taking into consideration previously determined differences between the reference temperatures and the temperature values of the control temperature indicators ().

Growing community of inventors

Hanau, Germany

Andreas Mühe