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Method for removing boron in polycrystalline silicon

A polysilicon and silicon liquid technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of high consumption of slag-forming agents and expensive high-temperature plasma equipment, reducing silicon loss, reducing boron removal effect, and increasing effect of concentration

Active Publication Date: 2013-05-01
福建兴朝阳硅材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method of the invention solves the problems of high dosage of slagging agent and expensive high-temperature plasma equipment, reduces the cost, and is convenient for industrial application

Method used

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  • Method for removing boron in polycrystalline silicon

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Weigh 50 kg of raw material industrial silicon, heat the silicon block into a graphite crucible of an intermediate frequency induction furnace, and melt it into a silicon liquid, keeping the temperature at 1500 ° C.

[0037] Weigh the composite slag forming agent NaCl~KCl~SiO2, by weight percentage, of which NaCl is 20%, KCl is 20%, SiO2 is 60%, and the mass ratio of composite slag agent to industrial silicon is 0.6:1, that is, 30kg.

[0038] Put the powdery composite slagging agent into the silicon liquid, continue heating to completely melt the slagging agent, and keep the temperature of the silicon liquid at 1500°C,

[0039] Preheat the graphite rod with the ventilation channel, insert the ventilation rod into the above-mentioned silicon liquid after preheating and start to pass oxygen, the gas flow rate of the oxygen is 5L / min, and the ventilation reaction time is 25min.

[0040] Turn on the high-voltage plasma generator, ionize part of the oxygen in the pipeline in...

Embodiment 2

[0043] Weigh 50 kg of industrial silicon as raw material, heat the silicon block in a graphite crucible of an intermediate frequency induction furnace, and melt it into a silicon liquid, keeping the temperature at 1700°C.

[0044] Weigh the composite slagging agent NaCl~KCl~SiO 2 , by weight percentage, where NaCl is 25%, KCl is 25%, SiO2 is 50%, and the mass ratio of composite slagging agent to industrial silicon is 0.8:1, that is, 40kg.

[0045] Put the powdery composite slagging agent into the silicon liquid, continue heating to completely melt the slagging agent, and keep the temperature of the silicon liquid at 1700°C.

[0046] Preheat the graphite rod with the ventilation hole, insert the ventilation rod into the above-mentioned silicon liquid after preheating and start the oxygen flow, the gas flow rate of the oxygen is 10L / min, and the ventilation reaction time is 30min.

[0047] Turn on the high-voltage plasma generator, ionize part of the oxygen in the pipeline into o...

Embodiment 3

[0050] Weigh 50 kg of raw industrial silicon, put the silicon material into a graphite crucible of an intermediate frequency induction furnace, heat it, and melt it into silicon liquid, keeping the temperature at 1800°C.

[0051] Weigh the composite slagging agent NaCl~KCl~SiO 2 , by weight percentage, of which NaCl is 30%, KCl is 30%, SiO2 is 40%, and the mass ratio of composite slagging agent to industrial silicon is 1:1, that is, 50kg.

[0052] Put the powdery composite slagging agent into the silicon liquid, continue heating to completely melt the slagging agent, and keep the temperature of the silicon liquid at 1800°C.

[0053] Preheat the graphite rod with the ventilation channel, insert the ventilation rod into the above silicon liquid after preheating, and start to ventilate the gas. The gas flow rate of the oxygen is 12L / min, and the ventilation reaction time is 35min.

[0054] Turn on the high-voltage ion generator, ionize part of the oxygen in the pipeline into oxy...

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Abstract

The invention relates to a novel method for removing boron in polycrystalline silicon. The method comprises the steps of: filling a silicon briquette into a graphite crucible of a medium-frequency induction furnace to heat, and melting to a silicon liquid; casting a slag former to the silicon liquid, continuously heating to completely melt the slag former, and maintaining temperature of the silicon liquid, wherein the slag former consists of NaCl, KCl and SiO2; preheating a graphite rod with a ventilating channel, and inserting the ventilating rod to the silicon liquid after adequate preheating and starting to introduce oxygen; meanwhile, starting a high pressure plasma generator, ionizing oxygen in an oxygen channel at room temperature to oxygen ions and injecting the oxygen ions to the silicon liquid through the graphite rod; and solidifying the silicon liquid obtained in an insulating furnace, and after a silicon ingot is cooled, removing slag blocks on the surface of the silicon ingot. According to the method, the slag amount can be effectively reduced, the silicon loss caused by silicon wrapped in slag is reduced, the cost of purifying polycrystalline silicon is lowered, the content of boron in the refined low boron polycrystalline silicon purified is lower, and the boron removing effect is good.

Description

technical field [0001] The invention relates to the technical field of polysilicon purification, in particular to a new method for plasma-assisted slagging and boron removal. Background technique [0002] The energy crisis and the pollution of the environment by traditional energy have become the main restrictive factors for the development of society and national economy. In order to maintain sustainable development, countries all over the world are actively adjusting their energy structure and vigorously developing renewable energy. Polycrystalline silicon solar cells have become a hot spot of global concern. The process of preparing high-purity polysilicon by using the improved Siemens method is relatively complicated, and the investment cost is high. Using it to prepare solar cells will greatly increase the price of the cells. The process of purifying polysilicon by metallurgy is relatively simple, the cost is low, and the pollution to the environment is relatively smal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 李伟生龚炳生叶文金
Owner 福建兴朝阳硅材料股份有限公司
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