Preparation of low-phosphorus solar-grade polysilicon

A solar-grade, polysilicon technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of high power consumption, pollution, and high cost of chemical methods, and achieve low cost, simple process, and good purification effect

Inactive Publication Date: 2008-11-12
SOUTH CHINA NORMAL UNIVERSITY
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  • Abstract
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Problems solved by technology

[0008] Chemical methods have high cost, high power consumption, complex equipment, and the risk of pollution and explosion; the purity of polysilicon prepared by physical methods is not very high for the time being

Method used

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  • Preparation of low-phosphorus solar-grade polysilicon
  • Preparation of low-phosphorus solar-grade polysilicon

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preparation example Construction

[0014] The preparation method of low-phosphorus solar-grade polysilicon of the present invention, its preferred embodiment is as follows figure 1 As shown, it includes the wet purification of metal silicon powder after phosphorus removal pretreatment and pulverization. The specific wet purification includes treating metal silicon powder with dilute hydrochloric acid, dilute nitric acid, aqua regia, and hydrofluoric acid for 7 to 9 hours respectively. 8 hours of processing time.

[0015] The temperature for wet purification may be 70-90°C, such as 80°C. The particle size of metal silicon powder can be 180-220 mesh, such as 200 mesh.

[0016] When performing wet purification, the concentration of hydrochloric acid can be 3.5-4.5 mol / L, the concentration of nitric acid can be 2.5-3.5 mol / L, and the concentration of hydrofluoric acid can be 0.3-0.4 mol / L. The preferred concentration is: hydrochloric acid 4.0mol / L, nitric acid 3.0mol / L, hydrofluoric acid 0.35mol / L.

[0017] Wet...

specific Embodiment

[0021] Including the high-temperature smelting stage and the wet purification stage, which are described below:

[0022] High temperature melting stage:

[0023] First, the 441# metal silicon block was crushed and ball milled, and the metal silicon powder with a particle size of 200 mesh (about 75 μm) was screened out with a sieve, and 5.000 g was weighed. Then weigh 0.250g of calcium metal, grind it into powder with an agate mortar, and then mix metal silicon powder and metal calcium powder according to m Si :m Ca =20:1 mass ratio fully mixed evenly.

[0024] After that, scoop the evenly mixed powder into an 87.0cm porcelain boat with a plastic medicine spoon, then put it into the middle part of a 21cm×17cm ceramic tube, and then insert the ceramic tube into a tube with a power of 2.5KVA and a furnace size of Φ18×180mm in the electric furnace. Connect the two ends of the ceramic tube with rubber plugs to form a closed environment, and then pass the protective gas high-pur...

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Abstract

The invention discloses a method for preparing low phosphorous solar-grade polycrystalline silicon. The method combines a high-temperature smelting method and a wet purification method, and comprises the steps as follows: metallic silicon powder is uniformly mixed with metallic calcium powder and is smelted at a high temperature under a high-pure argon atmosphere with fluidity; a part of phosphorus in the metallic silicon can be gasified, escape with flowing argon and be separated from the metallic silicon; at the same time, the phosphorus can react with the metallic calcium to generate calcium phosphide which is easily dissolved in acid; and the wet purification method is used after the high-temperature smelting method to reduce the content of phosphorus, other non-metallic impurities and various metallic impurities to the solar-grade polycrystalline silicon level after processing the metallic silicon for 8 hours respectively through 4.0 mol/L hydrochloric acid, 3.0 mol/L nitric acid, aqua regia and 0.35 mol/L hydrofluoric acid at a temperature of 80 DEG C under an ultrasonic oscillation atmosphere, thereby acquiring the low phosphorous solar-grade polycrystalline silicon. The method has the advantages of low cost, simple process and good purification effect.

Description

technical field [0001] The invention relates to a semiconductor processing technology, in particular to a method for preparing low-phosphorus solar grade polysilicon. Background technique [0002] Polycrystalline silicon is the basic raw material for preparing silicon solar cells, various silicon discrete devices and various silicon integrated circuits, and is an important raw material for the development of solar energy industry and information microelectronics industry. [0003] Metal silicon contains a large amount of metal impurities and non-metal impurities, which seriously affect the efficiency of solar cells and cannot meet the requirements of silicon raw materials required by the solar cell industry. It is necessary to purify 1N-2N industrial silicon to 6N-7N solar-grade polysilicon and 9N-12N electronic-grade polysilicon. [0004] In the prior art, there are chemical methods and physical methods for the purification of metal silicon. [0005] Chemical methods main...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 陈红雨杨春梅李核
Owner SOUTH CHINA NORMAL UNIVERSITY
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