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Method for removing boron and phosphorus in silicon at low temperature

A low-temperature, boron-phosphorous technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of special production technology for solar-grade high-purity silicon that is difficult to use in metallurgy, poor connection of purification methods, and inability to remove impurities simultaneously. , to achieve the effects of low equipment manufacturing requirements, shortened high-temperature treatment time, and reduced energy consumption

Active Publication Date: 2011-06-29
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the concentration of boron and phosphorus in the silicon liquid is low, its mass transfer rate is slow, resulting in an extremely slow removal rate. To meet the requirements, long-term high-temperature treatment is required, and the two impurities cannot be removed simultaneously.
Therefore, the removal of boron and phosphorus impurities is the bottleneck of metallurgical methods to reduce energy consumption.
At the same time, the various purification methods in the metallurgical method are poorly connected, and intermittent operations are mostly used, and the processing capacity of the equipment is small, resulting in extremely unstable product quality
These shortcomings make it difficult for metallurgical methods to become a dedicated production technology for solar-grade high-purity silicon

Method used

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  • Method for removing boron and phosphorus in silicon at low temperature

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Break 2g of metallurgical silicon (grade 1101, produced in Hunan) to below 500 microns, pickle with 5wt% hydrofluoric acid at 70°C for 6 hours, the weight ratio of silicon to acid is 1:20, rinse with deionized water after pickling , and dried to obtain pretreated silicon powder. The pretreated silicon powder is mixed with metal tin (purity 99.9wt%), heated to 1150°C to completely melt, and cooled to 600°C at 3.3°C / min to recrystallize the silicon. The silicon crystal was separated by centrifugation, pickled with dilute aqua regia (aqua regia:water:crude silicon weight ratio: 10:10:1), rinsed, and dried to obtain 1.95g of silicon crystal. The silicon crystals were melted, rapidly solidified into blocks, crushed, pickled, rinsed, and dried to obtain 1.91 g of high-purity silicon. The purification results are compared in Table 1.

[0029] Table 1

[0030] Impurity elements

[0031] Unit: ppmw

Embodiment 2

[0033] Break 2g of metallurgical silicon (grade 1101, produced in Hunan) to below 500 microns, pickle with 5wt% hydrofluoric acid at 70°C for 6 hours, the weight ratio of silicon to acid is 1:20, rinse with deionized water after pickling , and dried to obtain pretreated silicon powder. Mix the pretreated silicon powder with the centrifuged waste tin in Example 1, heat to 1150°C to completely melt, and cool to 600°C at 3.3°C / min to recrystallize the silicon. The silicon crystals were separated by centrifugation, pickled with dilute aqua regia (aqua regia:water:crude silicon weight ratio: 10:10:1), rinsed, and dried to obtain 1.90 g of silicon crystals. The silicon crystals were melted, rapidly solidified into blocks, crushed, pickled, rinsed, and dried to obtain 1.89 g of high-purity silicon. The purification results are compared in Table 2.

[0034] Table 2

[0035] Impurity elements

[0036] Unit: ppmw

Embodiment 3

[0038] Break 10g of metallurgical silicon (brand 1101, produced in Fujian) to below 500 microns, pickle with aqua regia at 70°C for 6 hours, the weight ratio of silicon to acid is 1:10, rinse with deionized water after pickling, and dry , to obtain pretreated silicon powder. The pretreated silicon powder is mixed with metal tin (purity 99.9wt%), heated to 1200°C to completely melt, and cooled to 600°C at 3.3°C / min to recrystallize the silicon. The silicon crystals were separated by centrifugation, pickled with dilute aqua regia (aqua regia:water:crude silicon weight ratio: 10:10:1), rinsed, and dried to obtain 9.84g of silicon crystals. The silicon crystals were melted, rapidly solidified into blocks, crushed, pickled, rinsed, and dried to obtain 9.75 g of high-purity silicon. The purification results are compared in Table 3.

[0039] table 3

[0040] Impurity elements

[0041] Unit: ppmw

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Abstract

A method for removing boron and phosphorus in silicon at low temperature belongs to the technical field of the production of high purity silicon and the method is to recrystallize and purify silicon in tin-based alloy liquid. The method comprises the following steps: crushing industrial silicon, pickling, pretreating, heating with tin-based alloy for complete melt-blending, cooling to ensure that silicon is recrystallized and precipitated, fast ingotting crystalline silicon, crushing and pickling to obtain the high purity silicon with low boron and phosphorus. In the method of the invention, the recrystallization temperature is 300-1400 DEG C and the silicon loss is less than 5%. Compared with the current metallurgical method for purifying silicon, the impurities of boron and phosphorus can be removed fast and simultaneously and the operating temperature is reduced by 600-1700 DEG C.

Description

technical field [0001] The invention belongs to the technical field of high-purity silicon production, in particular to a method for removing boron and phosphorus in silicon at low temperature, and quickly removes boron and phosphorus impurities in industrial silicon at low temperature. Background technique [0002] High-purity silicon is the most basic raw material for the electronic information industry and solar photovoltaic power generation industry. It is mainly used in integrated circuits, discrete devices and solar cells. In the past, high-purity silicon was almost completely used in the electronic information industry, and the waste from the production of electronic silicon wafers was used as raw materials for the photovoltaic industry. With the rapid development of the photovoltaic industry in recent years, the amount of high-purity silicon it consumes has far exceeded that of the electronics industry. [0003] The industrial production methods of high-purity silic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 赵立新王志郭占成
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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