Method for refining and purifying electronic-grade silane in polysilicon production process

Abstract

The invention discloses a method for refining and purifying electronic-grade silane in a polysilicon production process, which comprises the following steps of: 1) introducing crude silane into a lightness-removing column of which an operating pressure is 1.8 to 2.5 MPa and a top temperature is -120 to -80 DEG C, and removing nitrogen, methane and hydrogen from the top of the column; 2) making the crude silane flow out from the bottom of the column and enter a first weight-removing column of which the operating pressure is 1.8 to 2.5 MPa and the top temperature is -70 to -40 DEG C, and removing ethane, boron, phosphorus and the like from the bottom of the column; 3) making the silane exhausted from the top of the column enter series-wound absorption columns of which the operating pressures are all 1.6 to 2.3 MPa, and removing ethylene; and 4) making the silane enter a second weight-removing column of which the operating pressure is 1.6 to 2.3 MPa and the top temperature is -70 to 40 DEG C, and removing ethyl silicane. In the silane refined and purified by the method, the content of the nitrogen, the methane and the hydrogen is reduced to be below 1.5*10-9 and the content of the ethane, the ethyl silicane, diethylsilane, the boron and the phosphorus is reduced to be below 2.5*10-9; and the purity of the crude silane can be finally increased to be over 99.9999999 percent, which meets using requirements of electronics industry and semiconductor industry.

Description

technical field [0001] The invention relates to a compound preparation method, in particular to a method for refining and purifying electronic-grade silane in the production process of polysilicon. Background technique [0002] Polycrystalline silicon material is the most basic and main functional material in the electronic information industry and solar photovoltaic power generation industry. With the development of electronic information industry and solar photovoltaic new energy industry, the demand for polycrystalline silicon products will continue to increase. [0003] At present, the polysilicon production process of most enterprises in my country is the improved Siemens method, which actually uses trichlorosilane as the raw material to reduce polysilicon. The advantage of this method is that the process is mature, but it also has its disadvantages, such as high energy consumption, the power consumption is 350-500 degrees / kg; the reduction conversion rate is low, only ...

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Problems solved by technology

The advantage of this method is that the process is mature, but it also has its disadvantages, such as high energy consumption, the power consumption is 350-500 degrees / kg; the reduction conversion rate is low, only about 15%; The purity is 99.999%-99.9999% (technically called five 9 to six 9); at the same time, the pollution is relatively large, and the tail gas contains a large amount of silicon tetrachloride, which cannot be recycled, and accumulates more and more, forming an environmental protection problem that is difficult to solve

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