Polysilicon preparation method of recovering hydrogen chloride in circulating exhaust

Abstract

The invention relates to a production method of polysilicon which can recycle the chlorine hydride in tail gas. The method comprises: adopting industrial silicon and chlorine hydride as the raw material to react and generate trichlorosilane, purifying the trichlorosilane to be sent to a reduction furnace and react with hydrogen, thus generating the polysilicon by reduction and collecting the tailgas. The tail gas essentially comprises hydrogen, chlorine hydride and chlorsilane, wherein, the chlorsilane essentially comprises dichlorosilane, trichlorosilane and silicon tetrachloride. The improved production method of polysilicon further comprises the step of recycling the chlorine hydride in the tail gas by putting the recycled chlorine hydride into the production process of the polysilicon to react with the industrial silicon and generate trichlorosilane. By adopting dry treatment to recycle the chlorine hydride in the tail gas and applying the chlorine hydride to the production of polysilicon once again, the production method has the advantages of making full use of the raw materials, reducing pollutant, solving the problem of environment pollution, improving production quality and reducing cost.

Description

technical field [0001] The invention relates to an improved polysilicon production method, more specifically, relates to a polysilicon production method which can recover and recycle the hydrogen chloride in the tail gas. Background technique [0002] Polycrystalline silicon is the raw material for preparing monocrystalline silicon, which is ultimately used in the production of integrated circuits and electronic devices. It is one of the basic raw materials with the largest consumption and the highest purity requirements in the information industry. It is also a product and industry that the country encourages the development of. [0003] The world's advanced polysilicon production technology has always been monopolized by companies from the United States, Japan, and Germany. Each company has its own technical secrets and technical characteristics. After continuous research and development, it has formed its own production process. Set out, strictly control technology transf...

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Problems solved by technology

[0004] my country's polysilicon industry started in the 1950s, realized industrialization in the mid-1960s, and developed blindly in the early 1970s. There were more than 20 production plants, all using traditional Siemens technology, backward technology, serious environmental pollution, and material consumption. Large, high production costs, most enterprises lose money and stop production or change production one after another

[0005] The outstanding feature of the traditional polysilicon production process is the tail gas wet recovery technology, that is, the tail gas in the reduction furnace is initially pressurized to separate chlorosilane and then rinsed with water to recover hydrogen, but hydrogen chloride is not recovered. At the same time, due to the water rinse process, Oxygen, carbon dioxide and other impurity gases in the water will contaminate the hydrogen to be recovered, so a large amount of recovered hydrogen needs to be purified again. In addition, after the chlorosilane is hydrolyzed during the leaching process, a large amount of sewage will be generated, which requires further treatment and will also lead to environmental pollution. and high material consumption

Moreover, the hydrogen chloride produced in the production has not been fully utilized, which has not only wasted energy, but also caused environmental pollution.

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