Technological method for preparing polysilicon by silane method

A process method, polysilicon technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of reducing product yield and product quality, high single-pass conversion rate, fast homogeneous decomposition rate of silane, etc. Yield and quality, the effect of reducing the generation of silicon powder, and reducing the temperature of the gas phase

Active Publication Date: 2015-09-09
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

Because the thermal decomposition reaction rate of silane is very fast, the single-pass conversion rate is very high, and the amount of silane contained in the tail gas is very small, so the economy and feasibility of this process are not high.
CN103449439A discloses a safe production method for polysilicon produced by silane method. The main feature is that high-purity silane is prepared by using chlorosilane disproportionation method; and high-purity silane directly enters the reduction furnace to prepare high-purity polysilicon without passing through the silane storage tank. This method saves To remove the silane storage tank, use the bypass to adjust the silane feed amount, but it is difficult to achieve the stability of the reduction furnace feed
Due to the high gas phase temperature and fast homogeneous decomposition rate of silane in this process, a large amount of silicon powder will be generated, thereby reducing product yield and product quality

Method used

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  • Technological method for preparing polysilicon by silane method

Examples

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Comparison scheme
Effect test

Embodiment 1

[0018] Such as figure 1 As shown, a process method for preparing polysilicon by a silane method, the process equipment involved in the process method includes a reduction furnace 1, a cyclone separator 16, a filter 15, a waste heat exchanger 14, a steam drum 13, a water cooler 12, Circulating hydrogen compressor 11, cryogenic cooler 10 and connecting pipelines. Wherein the reduction furnace is a place where the chemical vapor deposition reaction occurs, including a bell jar cooling jacket 2 , a chassis cooling jacket 6 , silicon rods 3 and a gas chamber 7 . Described processing method specifically comprises the following steps:

[0019] (1) Silane / hydrogen mixture, wherein the volume fraction of the silane is 2%, enters the reduction furnace 1 through the gas chamber 7, the internal pressure of the reduction furnace 1 is 6MPaG, and the silicon rod 3 is heated by electrodes method, the surface temperature of the silicon rod is controlled at 900°C, the silane undergoes a heter...

Embodiment 2

[0027] The difference from Example 1 is that by increasing the cooling water flow rate, the temperature of the bottom plate and the inner wall of the bell jar of the reduction furnace 1 is maintained at 400° C., which can further reduce the deposition of elemental silicon on the bottom plate and the inner wall of the bell jar. The temperature of the reduction tail gas drops to 110°C after heat exchange through the waste heat heat exchanger 14, and the temperature of the circulating hydrogen drops to 40°C after heat exchange through the water cooler 12, and after being compressed, the temperature drops to 40°C in the low temperature cooler 10 The intermediate cooling medium is further cooled to -20°C, thereby further reducing the gas phase temperature in the reduction furnace 1, reducing the homogeneous cracking reaction rate of silane, reducing the generation of silicon powder, and improving the yield and quality of polysilicon products.

Embodiment 3

[0029] Different from Example 1, by adjusting the electrode heating rate and controlling the surface temperature of the silicon rod 3 at 800°C, the gas phase temperature in the reduction furnace 1 can be lowered, thereby reducing the homogeneous cracking reaction rate of silane and reducing silicon Powder generation, improve the yield and quality of polysilicon products.

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Abstract

The invention belongs to the field of a chemical technology and relates to a technological method for preparing polysilicon by a silane method. Processing equipment involved in the technological method comprises a reducing furnace, a cyclone separator, a filter, a waste heat exchanger, a steam drum, a water cooler, a circulating hydrogen compressor, a cryogenic cooler and a connecting pipe. In comparison with the prior art, the technological method has advantages of small silicon powder generation amount, high yield and quality of products, low comprehensive energy consumption and the like.

Description

technical field [0001] The invention belongs to the technical field of chemical industry and relates to a process for preparing polysilicon by a silane method. Background technique [0002] Polysilicon is widely used in the semiconductor and photovoltaic industries. In recent years, with the rapid development of the photovoltaic industry, the demand for polysilicon in the world has grown rapidly. In 2012, the output reached 170,000 tons, of which the consumption of photovoltaic industry accounted for as high as 85%. Polysilicon production technology is the most important link in the photovoltaic industry chain, and environmental protection and energy consumption issues have always been the bottleneck of the polysilicon industry. [0003] At present, the main process for producing polysilicon in the world is the improved Siemens method, and its production capacity accounts for about 80% of the world's total production capacity. The improved Siemens method, also known as the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/035
CPCY02P20/129
Inventor 李学刚肖文德梁正阎建民
Owner SHANGHAI JIAO TONG UNIV
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