Novel process for eliminating phosphorus-boron impurities contained in trichlorosilane

Abstract

The invention discloses a novel process for eliminating trace phosphorus and boron by sufficiently contacting trichlorosilane with a humidified inert gas through partial hydrolysis, comprising the following steps of: carrying out the partial hydrolysis in a reaction tower by contacting the trichlorosilane with a certain proportion of water vapors so as to achieve the purpose of eliminating trace phosphorus-boron impurities contained in the trichlorosilane; and previously configuring the water vapors with the inert gas according to a certain proportion, and uniformly mixing, wherein temperature inside the reaction tower is 60-70 DEG C, pressure is 0.1-0.6 MPa, and the inlet pressure of the inert gas is 0.3-1 MPa. The novel process can be directly implemented on a trichlorosilane rectifyingtower and has the advantages of easy operation, low cost, continuous production and good phosphorus-boron eliminating effect.

Description

technical field [0001] The invention relates to a new process for removing trace amounts of phosphorus and boron through partial hydrolysis by fully contacting trichlorosilane with moist inert gas. Background technique [0002] At present, more than 70% of polysilicon in the world is produced by the improved Siemens method. In the improved Siemens method, trichlorosilane is the main raw material for producing polysilicon, so the content of impurities in polysilicon depends on the raw material trichlorosilane. The content of impurities; in this production process, the impurities in trichlorosilane are all removed by rectification; for some impurities, such as iron, copper, manganese, etc., can be completely removed by rectification, but due to the The properties are similar to those of trichlorosilane, and the dispersion coefficient in it is close to 1, so it is difficult to remove. [0003] At present, the method of removing phosphorus and boron in domestic enterprises is m...

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Problems solved by technology

[0002] At present, more than 70% of polysilicon in the world is produced by the improved Siemens method. In the improved Siemens method, trichlorosilane is the main raw material for producing polysilicon, so the content of impurities in polysilicon depends on the raw material trichlorosilane. The content of impurities; in this production process, the impurities in trichlorosilane are all removed by rectification; for some impurities, such as iron, copper, manganese, etc., can be completely removed by rectification, but due to the The properties are similar to those of trichlorosilane, and the dispersion coefficient in it is close to 1, so it is difficult to remove

[0003] At present, the method of removing phosphorus and boron in domestic enterprises is mainly realized by increasing the number of rectification tower stages and the number of trays. bad

[0004] Some companies at home and abroad try to use adsorption to remove trace phosphorus and boron impurities in trichlorosilane, and there are many research reports in this field in recent years; but most of the successful reports on this direction are concentrated in laboratory micro-tests In large-scale industrial production, the removal effect of phosphorus and boron is not good, and it is easy to cause safety accidents such as fire or explosion.

[0005] Foreign polysilicon enterprises have conducted a lot of research in the field of phosphorus and boron removal by complexation in the past two decades, and have searched for hundreds of complexing agents, among which the best effect is sodium tetrahydropyrrole dithiocarbamate, which can The boron content in trichlorosilane is reduced to below 1ppb, but the complexing agent is dispersed unevenly in the complexing method and cannot be reused, the preparation process is complex and demanding, the process is also very complicated, and the overall cost is high

[0006] All current methods for removing phosphorus and boron impurities in trichlorosilane at home and abroad have the following disadvantages: (1) complex operation, expensive equipment and raw materials used; (2) certain danger; (3) phosphorus and boron removal materials in Uneven distribution in trichlorosilane; (4) introduction of secondary impurities; (5) poor effect of phosphorus and boron removal

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