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A kind of metal silicon surface treatment purification method

A surface treatment and purification method technology, applied in the direction of non-metallic elements, chemical instruments and methods, silicon compounds, etc., can solve the problems that metal impurities cannot be removed or are difficult to remove

Inactive Publication Date: 2012-02-01
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It is generally believed that the segregation coefficients of most metal impurities in silicon are very small, and can be removed by directional solidification; however, the segregation coefficients of B and P (0.8 and 0.35, respectively) are relatively large, and it is difficult to remove them by directional solidification.
Moreover, when the concentration of metal impurities is very high (greater than 1ppmw), the metal impurities cannot be removed by directional solidification

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] 1) Degreasing and cleaning metallic silicon with a particle size of 0.05 mm in acetone by ultrasonic waves;

[0019] 2) The product of step 1) is ball-milled to 0.005 mm in ethanol as a medium, and the resulting product is dried under an argon atmosphere;

[0020] 3) Put the product of step 2) into an annealing furnace, heat to 1050°C, keep it warm for 30 minutes, cool down to 700°C at a rate of 1°C per minute, keep it warm for 30 minutes, and then cool with the furnace;

[0021] 4) The product of step 3) is taken out, soaked for 1 hour with 5% hydrochloric acid and 1% hydrofluoric acid at a volume ratio of 1:1, and then cleaned with deionized water. High-grade metal silicon materials with a purity of 4N can be obtained. (The impurity content has been tested by ICPMS, see the table below for details, ppmw refers to one millionth by mass, that is, there is 1 microgram of metal impurities per gram of silicon)

[0022] impurity atoms

Embodiment 2

[0024] 1) Degreasing and cleaning metal silicon with a particle size of 1mm in acetone by ultrasonic;

[0025] 2) The product of step 1) is ball-milled to 0.01 mm with acetone as the medium, and the resulting product is dried with argon;

[0026] 3) Put the product of step 2) into an annealing furnace, rapidly heat to 1200°C, keep it warm for 60 minutes, cool down to 750°C at a rate of 5°C per minute, keep it warm for 60 minutes, and then cool with the furnace;

[0027] 4) The product of step 3) is taken out, soaked for 3.5 hours with 10% hydrochloric acid and 5% hydrofluoric acid with a mass percentage concentration of 1:1, and then cleaned with deionized water. High-grade metal silicon materials with a purity of 5N can be obtained. (The content of impurities has been tested by ICPMS, see the table below for details)

[0028] impurity atoms

Embodiment 3

[0030] 1) Degreasing and cleaning metallic silicon with a particle size of 10 mm in acetone by ultrasonic waves;

[0031] 2) The product of step 1) is ball-milled to 0.03 mm in ethanol as a medium, and the resulting product is dried with argon;

[0032] 3) Put the product of step 2) into an annealing furnace, rapidly heat to 1350°C, keep it for 120 minutes, cool down to 900°C at a rate of 10°C per minute, keep it for 150 minutes, and then cool with the furnace;

[0033] 4) The product of step 3) is taken out, soaked with 20% hydrochloric acid and 10% hydrofluoric acid in a volume ratio of 1:1 for 5 hours, and then cleaned with deionized water. High-grade metal silicon materials with a purity of 4.5N can be obtained. (The content of impurities has been tested by ICPMS, see the table below for details)

[0034] impurity atoms

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PUM

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Abstract

The invention discloses a method for surface treatment and purification of metal silicon, which comprises the following steps: first degreasing and cleaning the metal silicon; then using alcohols or ketones as the medium for the degreased and washed metal silicon, and drying with argon gas after ball milling dry; then heat the dried product quickly, keep it warm and then cool it down, and cool it after keeping it warm; take out the cooled product, soak it in a mixed solution of hydrochloric acid and hydrofluoric acid, and clean it with deionized water. The invention utilizes the principle of external diffusion of impurities in silicon and gettering on the surface. First, a large number of defects are artificially caused on the surface of metal silicon to form a damaged layer. The metal silicon is initially purified to a purity of 99.99%-99.999% (4-5N), and can be used as a silicon material for solar cells or a further purified raw material for subsequent purification processes.

Description

technical field [0001] The invention relates to a method for purifying metallic silicon, in particular to a method for purifying the surface of metallic silicon. Background technique [0002] Solar energy is widely distributed and is an inexhaustible clean energy. Solar cells can convert solar energy into electrical energy, but the current price of solar cells is relatively high, especially the cost of crystalline silicon cells, which is the main body of the photovoltaic market, is still very high, which seriously affects the promotion and use of solar energy. [0003] According to authoritative forecasts, the photovoltaic market in the next 10 years will still be dominated by crystalline silicon solar cells. In the past five years, the price of solar-grade silicon raw materials has risen to $500 / kg. Although it has fallen back to about $100 / kg, the cost of materials still accounts for more than 25% of the total cost, and it has become one of the most difficult links to red...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 余学功顾鑫杨德仁
Owner ZHEJIANG UNIV
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