Process and apparatus for manufacturing polycrystalline silicon ingots

Abstract

The present application describes a process and apparatus for producing polycrystalline silicon ingots. During the process, a crucible is arranged in a process chamber, wherein the crucible is filled with solid silicon material or is being filled with silicon material in the process chamber. The crucible is located with respect to at least one diagonal heater in such a way that the diagonal heater is located laterally offset to and generally above the silicon ingot to be produced. Thereafter, the solid silicon material in the crucible is heated above the melting temperature of the silicon material in order to form molten silicon in the crucible, and thereafter, the silicon material in the crucible is cooled down below the solidification temperature of the molten silicon, therein a temperature profile in the silicon material during the cooling phase is controlled at least partially via the at least one diagonal heater. The apparatus comprises a process chamber, a crucible holder inside the process chamber, and at least one diagonal heater in the process chamber. The diagonal heater is located laterally with respect to the crucible holder and extends generally perpendicular thereto and is spaced from the crucible holder in a vertical direction at such a distance that the diagonal heater is located generally above a polycrystalline silicon ingot to be formed in the crucible. The diagonal heater is stationary with respect to the crucible holder when the process chamber is closed.

Description

technical field [0001] The present invention relates to a process and equipment for manufacturing polycrystalline silicon ingots. Background technique [0002] In the field of semiconductors and solar cells, it is known to produce polycrystalline silicon ingots by melting high-purity silicon material in melting vessels or crucibles. For example, document DE 199 34 94 032 describes a corresponding device for this purpose. The apparatus generally consists of an isolator with heating elements, a crucible and a loading unit in the isolator. The following are provided as heating elements: a bottom heater arranged below the crucible, side heaters arranged on each side of the crucible, and a top heater arranged above the crucible. [0003] During the manufacture of silicon ingots, the crucible is loaded with the isolation box open, and thereafter granular silicon is melted in the crucible by the heating element, with the isolation box closed. After reloading with additional sili...

AI Technical Summary

Problems solved by technology

In cases where only bottom heaters are used, the desired control of the temperature profile may not be achieved as the molten silicon will solidify from the bottom to the top as mentioned above

On the other hand, the use of side heaters causes the phase boundaries to bend substantially during directional solidification

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