Composite type heating method and device for polycrystalline silicon smelting

Abstract

The invention discloses composite type heating method and device for polycrystalline silicon smelting, belonging to the technical field of purifying polycrystalline silicon by using the physico-metallurgy technology, in particular relates to a method and a device for smelting the polycrystalline silicon by using a mode of composite heating of an induction coil and a graphite heater. In the method, the composite type heating is carried out on a heating zone by synchronously using two modes of induction heating and radiant heating, silicon materials are fused and smelted, and a fusant disengages the heating zone through the movement of an ingot-pulling device to realize directional solidification. In the device, a shell of the device consists of a vacuum cover and a vacuum drum, wherein an internal cavity of the vacuum drum is a vacuum chamber, and the vacuum chamber is internally provided with the induction coil for induction heating and the graphite heater for radiant heating. The invention effectively utilizes the high efficiency of the induction heating and the stability of the radiant heating, ensures the stability of the smelting process, reduces the energy consumption and enhances the heating efficiency, and the method is simple and easy to operate and suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of purifying polysilicon by using physical metallurgy technology, and in particular relates to a method and a device for melting polysilicon by means of combined heating of an induction coil and a graphite heater. Background technique [0002] High-purity polysilicon is the main raw material for solar cells. The preparation of high-purity polysilicon abroad mainly uses the Siemens method, specifically the silane decomposition method and the gas-phase hydrogen reduction method of chlorosilane, in which SiHCl 3 The Siemens method is currently the mainstream technology for polysilicon preparation. SiHCl 3 The useful deposition ratio of the method is 1×10 3 , is SiH 4 100 times. The deposition rate of the Siemens method can reach 8-10 μm / min. The conversion efficiency of one pass is 5% to 20%, and the deposition temperature is 1100°C, second only to SiCl 4 (1200°C), the power consumption is about 120kWh / k...

AI Technical Summary

Problems solved by technology

The disadvantage of the Siemens method is that it adopts backward thermal chemical vapor deposition in the core link of the process. There are too many links in the process and the conversion rate is low at one time, which leads to a long process time and increases the cost of materials and energy consumption.

If the induction heating method is used alone, it is difficult to ensure the stability of the induction electromagnetic field due to uncertain factors, and the electromagnetic stirring effect also affects the solidification behavior and solidification structure of the ingot.

If the radiation heating method is used alone, due to the low temperature at the beginning of heating, the graphite heater needs to consume a lot of energy, and the heating time will be very long

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