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Boron removing method for multicrystal silicon

A technology of polysilicon and polysilicon blocks, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of high cost, high power consumption, complex equipment, etc., and achieve low power consumption, low cost, and simple equipment Effect

Inactive Publication Date: 2007-10-17
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These chemical methods effectively purify and remove various impurities such as metal, boron and phosphorus in silicon through the change process of silicon composition, but they have high cost, large power consumption, complicated equipment, and the risk of pollution and explosion.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Example 1: Industrial silicon blocks were pulverized, ball milled and screened to obtain silicon powder with a diameter of 100 mesh. Use an electromagnet to absorb a small amount of iron powder in the silicon powder, and use toluene, acetone and ethanol to degrease the silicon powder after iron absorption in sequence, and rinse it with hot and cold deionized water. Put the treated silicon powder into a quartz boat, and then put it into an oxidation furnace for wet oxygen oxidation. The oxygen flow rate is 700ml / min, the oxidation temperature is 740°C, and the wet oxygen oxidation is 5h. The appearance of the silicon powder is dark blue, and the thickness of the oxide layer is 0.3 μm. After cooling, take out the silicon powder and etch it in a plastic container with chemically pure dilute hydrofluoric acid (hydrofluoric acid: water = 1:2) and stir repeatedly for 30 minutes to corrode the oxide layer on the surface of the sample; wash and dry it with deionized water Get ...

Embodiment 2

[0025] Example 2: Pulverize polysilicon blocks, ball mill, and screen to obtain silicon powder with a diameter of 80 meshes, and use an electromagnet to absorb iron powder in the silicon powder. The silicon powder is deoiled with organic solvents carbon tetrachloride, acetone and ethanol in sequence, and rinsed with hot and cold deionized water. Put the deoiled and iron-removed silicon powder into a ceramic container, and then put the ceramic container into a high-temperature oxidation furnace for wet oxygen oxidation. The oxygen flow rate is 800ml / min, the oxidation temperature is 600°C, the wet oxygen oxidation is 8h, and then cooled. Put the silicon powder taken out after cooling into chemically pure dilute hydrofluoric acid solution to corrode to remove the oxide layer on the surface of the sample. The volume ratio of hydrofluoric acid:water=1:1. Repeatedly wash the silicon powder with deionized water until the outflowing water is neutral, use a centrifuge to remove the wa...

Embodiment 3

[0026] Example 3: Pulverize polysilicon blocks, ball mill, and screen to obtain silicon powder with a diameter of 200 meshes, and use an electromagnet to absorb iron powder in the silicon powder. The silicon powder was degreased with organic solvents trichlorethylene, acetone and ethanol in sequence, and rinsed with hot and cold deionized water. Put the silicon powder that has been degreased and ironed into a ceramic container, and then put the ceramic container into a high temperature oxidation furnace for wet oxygen oxidation. The oxygen flow rate is 750ml / min, the oxidation temperature is 1200°C, the wet oxygen oxidation is 0.5h, and then cooled. Put the silicon powder taken out after cooling into chemically pure dilute hydrofluoric acid solution to corrode to remove the oxide layer on the surface of the sample, and the volume ratio of hydrofluoric acid:water=1:4. Repeatedly wash the silicon powder with deionized water until the outflowing water is neutral, use a centrifuge...

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Abstract

A method for removing boron from polysilicon relates to a polysilicon, in particular to a simple, low cost and small pollution method for removing boron from polysilicon. The present invention provides a method for removing boron from polysilicon with simple process, lower cost, safe technology, and small pollution. The polysilicon block is subjected to pulverization, ball milling and sieving to obtain silicon powder which is deoiling treated by using organic solvent, and the iron power contained in the silicon powder is removed too; the obtained silicon powder is put into a container which is put into a high-temperature furnace, wherein the silicon powder is subjected to wet-oxygen oxidation and recooling; the silicon powder after recooling is put into hydrofluoric acid solution to be corrupted so as to remove the surface oxidation layer; and then the silicon powder is scrubbed repeatedly by water until the washing liquid is neutral; finally, the silicon powder is dried to obtain the object product. The spectral analysis of the silicon powder shows that the boron content can be reduced by 1~3 times once, the present invention is totally compatible with the acid cleaning purification technology, and aluminium can be effectively removed.

Description

technical field [0001] The invention relates to polysilicon, in particular to a method for removing boron impurities in polysilicon with simple method, low cost and less pollution. 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 a strategic material for the development of solar energy industry and information microelectronics industry. To purify 1N-2N industrial polysilicon to 6N-7N solar-grade polysilicon and 9N-12N electronic-grade polysilicon, existing methods include physical methods and chemical methods. Physical methods (by Chen Zhiming and Wang Jiannong, Materials Physics Foundation of Semiconductor Devices, Science Press, first edition in May 1999, pages 29-30) do not change the composition of silicon, mainly using Fe, Al, The equilibrium segregation coefficient K of more than a dozen metal impurities such as Au in silic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 陈朝庞爱锁
Owner XIAMEN UNIV
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