Method for purifying high-purity hydrogen or high-purity chlorosilane with phosphorus-containing impurities

Abstract

The invention discloses a method for purifying high-purity hydrogen or high-purity chlorosilane with phosphorus-containing impurities, comprising the following steps: heating the high-purity hydrogen with phosphorus-containing impurities to 500-800°C, and reacting the phosphorus-containing impurities in the high-purity hydrogen with hydrogen Generate phosphine, and then adsorb the phosphine through molecular sieves to obtain purified high-purity hydrogen. The phosphorus-containing impurities in the high-purity hydrogen containing phosphorus impurities are converted into phosphine by heating, so that all kinds of phosphorus-containing impurities are reduced and reacted to form the same substance phosphine, because the molecular sieve has a large impact on the gas passing through it. Selective adsorption of phosphine, thereby improving the adsorption capacity of phosphine in high-purity hydrogen with phosphorus impurities, thus greatly improving the purity of purified high-purity hydrogen, and further improving the production of purified high-purity hydrogen as raw materials The quality of the polysilicon reduces the impurity content in the polysilicon.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and in particular relates to a method for purifying high-purity hydrogen or high-purity chlorosilane with phosphorus-containing impurities. Background technique [0002] High-purity crystalline silicon is an important solar photovoltaic material. High-purity hydrogen and high-purity chlorosilane are the key raw materials for the production of high-purity polysilicon. The removal of phosphorus-containing impurities in high-purity hydrogen and high-purity chlorosilane determines the quality of the produced polysilicon. The key factor. [0003] For the improved Siemens method, it is to purify trichlorosilane through repeated lightening and heavy-lifting treatments through rectification. Most domestic enterprises use this method to produce polysilicon. This method is easy to operate and is suitable for large-scale industrial production. It can obtain an impurity mass fraction of 10 -...

AI Technical Summary

Problems solved by technology

200580039715.7 Invented the simultaneous use of diphenylthiocarbazone (DTZ) and triphenylchloromethane (TCM) as complexing agents, TCM can fully complex boron impurities and some metal impurities, DTZ can complex most metals , the combination of the two can show the best complexation efficiency, this method can reduce the mass fraction of boron to 3×10 －7 , the mass fraction of phosphorus is reduced to 5×10 －9 ;The disadvantage is that it adopts intermittent operation, and the total reflux time is longer (more than 3h) when starting up. This process cannot meet the requirements of continuous large processing capacity.

Studies have shown that the use of such complexes can fully react with the impurities in chlorosilanes, reducing the impurity content to one part per billion. The disadvantage is that it is difficult to realize industrialization of this method, and the complexing agent is expensive

[0005] 200810180270.X invention discloses a method for removing boron and phosphorus ions in chlorosilane materials by using resin. The inventive method can remove more than 95% of trace boron and phosphorus ions contained in chlorosilane materials, but no specific adsorption resin is disclosed name

[0006] The technical feature of the above chlorosilane purification method is to use wet nitrogen rectification, oxidative rectification, complex rectification and adsorption methods to purify chlorosilanes, which has the following disadvantages: the moisture content in the wet nitrogen rectification is difficult to accurately control, if the water content is excessive , resulting in the hydrolysis of chlorosilane, producing hydrolyzate, blocking the equipment pipeline, and at the same time, producing a small amount of hydrochloric acid, which is easy to corrode the equipment, which has caused phosphorus impurities in the equipment pipeline to enter the back-end process due to corrosion, affecting product quality

Oxygen is introduced during the operation of the oxidative distillation, and it is difficult to effectively control the amount of oxygen introduced. If the oxygen is excessive, excessive intermediates will be produced, resulting in new impurities that will remain in the chlorosilane. At the same time, the excess oxygen may enter the back-end process. There are security risks

The disadvantage of complex distillation is that it adopts intermittent operation, and the total reflux time is longer (more than 3h) when starting up. This process cannot meet the requirements of continuous large-scale processing capacity, and continuous industrial production is difficult. In order to make chlorosilane and complexing agent For full mixing, it is necessary to increase the stirring device, and at the same time, it is also necessary to increase the follow-up processing device of the complex, thus increasing the operating cost. Due to the high price of the complexing agent, the operating cost is also increased

Compared with the traditional method, the adsorption method can reduce the rectification workload and save costs. However, in the liquid phase adsorption process, the impurities in the adsorbent, due to the competitive adsorption of metals, boron, carbon and other impurities in the chlorosilane and phosphorus impurities, affect the Adsorption performance

At the same time, due to the various forms of phosphorus impurities in chlorosilanes and the diversity of their physical and chemical properties, it is impossible to determine highly selective adsorbents and complexing agents.

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