Cleaning method of polycrystalline silicon raw material

A polysilicon and raw material technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of high cost, achieve low cost, reduce the content of metal impurities and boron, and improve the effect of cleaning

Inactive Publication Date: 2013-04-03
PROPOWER RENEWABLE ENERGY SHANGHAI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the cost of directly using 1N-2N industrial-grade polysilicon for directional solidification, regional purification, and Czochralski single crystal separation and purification is still very high.

Method used

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  • Cleaning method of polycrystalline silicon raw material

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Preferred embodiment 1 of the present invention is:

[0036] The polysilicon material containing impurities is crushed first, and the mesh size of the sieved silicon powder is 50 mesh, and then the iron in the silicon material is absorbed by a magnet. Then put the silicon powder into 40% hydrogen peroxide solution and soak for 24 hours. Then put the silicon powder into a high-temperature container, and then put the container into a high-temperature furnace for wet oxygen oxidation. The oxygen flow rate is 1000 ml / min, the oxidation temperature is 1200 ° C, and the oxidation time is 1 hour. The appearance of silica fume is purple or dark red, and then cools down. Put the silicon powder taken out after cooling into the mixed acid whose concentration is 20% hydrochloric acid and 40% hydrofluoric acid and soak for 6 hours to remove impurities such as oxide layer and iron in the sample, wherein the hydrochloric acid and The volume ratio of hydrofluoric acid is 3:1; the sil...

Embodiment 2

[0038] Preferred embodiment 2 of the present invention is:

[0039] The polysilicon material containing impurities is crushed first, and the sieved silicon powder has a mesh size of 200 mesh, and then the iron in the silicon material is absorbed by a magnet. Then put the silicon powder into a hydrogen peroxide solution with a concentration of 30% and soak for 12 hours. Then put the silicon powder into a high-temperature container, and then put the container into a high-temperature furnace for wet oxygen oxidation. The oxygen flow rate is 1000 ml / min, the oxidation temperature is 800°C, and the oxidation time is 8 hours. The appearance of silica fume is purple or dark red, and then cools down. Put the silicon powder taken out after cooling into the mixed acid whose concentration is 30% hydrochloric acid and 40% hydrofluoric acid and soak for 4 hours to remove impurities such as oxide layer and iron in the sample, wherein the hydrochloric acid and The volume ratio of hydrofluo...

Embodiment 3

[0041] Preferred embodiment 3 of the present invention is:

[0042]The polysilicon material containing impurities is crushed first, and the mesh size of the sieved silicon powder is 400 mesh, and then the iron in the silicon material is absorbed by a magnet. Then put the silicon powder into 20% hydrogen peroxide solution and soak for 2 hours. Then put the silicon powder into a high-temperature container, and then put the container into a high-temperature furnace for wet oxygen oxidation. The oxygen flow rate is 1000 ml / min, the oxidation temperature is 400°C, and the oxidation time is 24 hours. The appearance of silica fume is purple or dark red, and then cools down. Soak the silicon powder taken out after cooling in a mixed acid with a concentration of 30% hydrochloric acid and 40% hydrofluoric acid to remove impurities such as oxide layer and iron in the sample, wherein the hydrochloric acid and hydrofluoric acid in the mixed acid The volume ratio of the acid is 1:1; the s...

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Abstract

The invention discloses a cleaning method of a polycrystalline silicon raw material. The cleaning method comprises the following steps of crushing a polycrystalline silicon raw material, removing iron from silicon powder by a magnet, immersing the silicon powder in a hydrogen peroxide solution for 2-24h, carrying out wet-oxygen oxidation of the silicon powder, immersing the silicon powder in a mixed acid of hydrochloric acid and hydrofluoric acid, immersing the silicon powder in hydrofluoric acid for corrosion, putting the silicon powder into an ultrasonic water tank, carrying out ultrasonic cleaning, and drying the silicon powder in a vacuum furnace to obtain a target product. The cleaning method removes metal impurities in the silicon powder by pickling, realizes diffusion of the impurities into SiO2 by utilization of a ratio of the equilibrium concentration of boron in silicon to the equilibrium concentration of boron in SiO2, wherein the ratio is less than 1, and realizes removal of SiO2 containing a large amount of boron by pickling so that 4N-5N polycrystalline silicon can be obtained. The cleaning method has the advantages of simple processes, low cost, good safety and low pollution.

Description

technical field [0001] The invention relates to a method for cleaning polysilicon raw materials. Background technique [0002] Polycrystalline silicon raw materials are the main raw materials for preparing silicon solar cells and manufacturing integrated circuit substrates, and are an important cornerstone for the development of information industry and new energy industry. In recent years, the country has advocated the development of new energy, especially the development and utilization of renewable new energy. Solar energy, as a renewable and non-polluting energy, has led to the rapid development of the solar energy industry, resulting in a shortage of polysilicon for solar cells. The existing methods for purifying 1N-2N industrial-grade polysilicon into 6N-7N solar-grade polysilicon include chemical methods and physical methods. Chemical methods include Siemens method, modified Siemens method and silane method. The Siemens method is to react Si and HCl to generate SiHC...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 史珺卿喻楚李华杰
Owner PROPOWER RENEWABLE ENERGY SHANGHAI
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