Thermal field structure for drawing zone-melting 8-12-inch silicon single crystal

Abstract

The invention provides a thermal field structure for drawing a zone-melting 8-12-inch silicon single crystal. The thermal field structure comprises a sharp-angled coil, a middle thermal shield and a lower thermal shield, wherein the sharp-angled coil is located at a melting zone between a polycrystal rod and a single-crystal rod in a furnace body; the sharp-angled coil is a round coil; a coil eye is formed in the center of the round coil; a plurality of coil seams which are in circumferential distribution by taking the center of the round coil as a starting point are arranged between the outer edge of the round coil and the coil eye; the coil between every two adjacent coil seams forms a sharp-angled step; a ring-shaped steel plate is arranged in the furnace body; the middle thermal shield is fixed to the upper end of the ring-shaped steel plate; the lower thermal shield is fixed to the lower end of the steel plate. According to the thermal field structure for drawing the zone-melting 8-12-inch silicon single crystal, owing to arrangement of the sharp-angled coil, the raw material melting capability of the coil can be enhanced, the power of the coil can be reduced, and poor crystal pulling waist forms caused by high power are avoided or reduced; owing to arrangement of the middle thermal shield and the lower thermal shield, the probability of dislocation is lowered.

Description

technical field [0001] The invention belongs to the field of single crystal silicon production equipment, and in particular relates to a thermal field structure for melting 8-12 inch silicon single crystal in a drawing zone. Background technique [0002] The growth of monocrystalline silicon by zone melting is currently the most advanced application technology for the production of single crystal silicon, so it is used in high-end power electronic devices. With the development of power electronic devices, large diameters have become an inevitable trend. The increase of the single crystal diameter may lead to the following problems: Firstly, the diameter of the raw material increases, and the power of the required generator increases accordingly, which leads to an increase in the probability of ionization breakdown, and an increase in the probability of uneven feeding or puncture of the feeding material ; Secondly, the increase of thermal stress leads to an increase in the pr...

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Problems solved by technology

[0002] The growth of single crystal silicon by zone melting method is the most advanced application technology for the production of single crystal silicon at present, so it is used in middle and high-end power electronic devices. With the development of power electronic devices, large diameter has become an inevitable trend. The increase of the single crystal diameter may lead to the following problems: Firstly, the diameter of the raw material increases, and the power of the required generator increases accordingly, which leads to an increase in the probability of ionization breakdown, and an increase in the probability of uneven feeding or puncture of the feeding material. ; secondly, the thermal stress increases, resulting in an increase in the probability of dislocation generation; again, the gas in the zone melting growth furnace and the convection velocity in the melt increase, which is prone to temperature fluctuations, resulting in free energy fluctuations at the interface and dislocations

[0003] In the prior art, the thermal stress of the molten silicon single crystal in the large-diameter area is generally controlled by adding a magnetic field and adding a reflective ring between the coil and the insulation cylinder, thereby reducing the probability of dislocation generation. However, the molten silicon single crystal in the large-diameter area The problem of difficult chemical materials has not been solved, and at the same time, the thermal stress of zone-melting silicon single crystal has not been significantly reduced.

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