Production technology and device for boron-removing and purification of polysilicon by adopting electromagnetic induction melting assisted with high-temperature plasma

A technology of high-temperature plasma and production technology, which is applied in the direction of silicon compounds, inorganic chemistry, non-metallic elements, etc., can solve the problems that the B removal effect is difficult to reach solar-grade polysilicon, complex equipment, and expensive costs, etc., so as to facilitate industrialization and reduce Energy consumption, the effect of solving the problem of arc ignition

Inactive Publication Date: 2010-03-17
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The current industrial application of blowing slagging method has the following problems: First, the removal effect of B is still difficult to meet the requirements of solar-grade polysilicon
However, due to the use of non-transferred arc, its effective power is generally only 40% to 50% of the total power. Since the cathode and anode of the plasma arc are in the gun

Method used

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  • Production technology and device for boron-removing and purification of polysilicon by adopting electromagnetic induction melting assisted with high-temperature plasma

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] 1) Weigh 50 kg of raw metal silicon with a B concentration of 8 ppmw.

[0054] 2) Put the raw metal silicon into the high-strength graphite crucible, start the mechanical rotary vane pump to vacuum, when the vacuum reaches 500Pa, switch on the intermediate frequency induction coil power supply, the power is 50kw, until the silicon is completely melted.

[0055] 3) Increase the power of the intermediate frequency power supply to 60kw, make the temperature of the silicon liquid reach 1600°C, start the plasma melting system, and pass in 99.5% Ar + 0.5% H 2 O, the ventilation flow is 25L / min.

[0056] 4) Turn the arc ignition device parallel to the high-strength graphite crucible, and lower the plasma gun to a position 40mm above the arc ignition device, adjust the given voltage to 180V, and start the arc ignition. After the arc ignition is completed, rotate the arc ignition device 90-180 degrees in parallel to make it leave the surface of the silicon liquid.

[0057] 5) Adjust the...

Embodiment 2

[0060] The process is the same as in Example 1. After the silicon is completely melted, increase the power of the intermediate frequency power supply to 70kw, make the temperature of the silicon liquid reach 1700℃, and pass in 98.75% Ar+1.25% H 2 O, adjust the given current to 360A, the plasma power to 64kw, adjust the plasma arc length to 170mm, and perform plasma melting on the surface of the silicon liquid for 30 minutes. The silicon liquid was poured into a graphite mold for casting, left to stand, and the silicon ingot was taken out after cooling. The B content in the polycrystalline silicon ingot was measured by a secondary ion mass spectrometer (SIMS) to be 0.07 ppmw.

Embodiment 3

[0062] The process is the same as in Example 1. After the silicon is completely melted, increase the power of the intermediate frequency power supply to 80kw, make the temperature of the silicon liquid reach 1800℃, and pass in 99% Ar+1% H 2 O, adjust the given current to 525A, the plasma power to 92kw, adjust the plasma arc length to 320mm, and perform plasma smelting on the surface of the silicon liquid for 20 minutes. The silicon liquid was poured into a graphite mold for casting, left to stand, and the silicon ingot was taken out after cooling. The B content in the polycrystalline silicon ingot was measured by a secondary ion mass spectrometer (SIMS) to be 0.99 ppmw.

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Abstract

The invention discloses a poduction technology and a device for boron-removing and purification of polysilicon by adopting electromagnetic induction melting assisted with high-temperature plasma, andprovides a poduction technology and a polysilicon boron-removing and purification device which have low cost and high efficiency, are applicable to industrial popularization and adopt electromagneticinduction melting assisted with high-temperature plasma. The purification device is provided with a vacuum system, a mid-frequency induction melting system, a transferred arc plasma melting system anda pouring graphite mould. The technology comprises the following steps: putting the silicon metal into a crucible, vacuumizing, and heating and melting the silicon metal; increasing the power after melting to lead the liquid silicon temperature to be kept between 1600 DEG C and 1800 DEG C, starting the plasma melting system, declining a plasma gun above an arc initiating device, and introducing working gas for arc initiating; moving the arc initiating device off after arc initiating is finished, adjusting specified current and plasma arc length, after conducting plasma melting to the liquid silicon surface, zeroing the specified current, disconnecting the plasma arc, rising the plasma gun, turning off the air supply, pouring the liquid silicon into the mould, and taking silicon ingots outafter standing and cooling.

Description

Technical field [0001] The invention relates to a polycrystalline silicon boron removal and purification technology, in particular to a production process and a device for purifying polycrystalline silicon by using electromagnetic induction melting to assist high-temperature plasma boron removal and purification. Background technique [0002] Due to the energy crisis and traditional energy pollution to the environment, in order to maintain sustainable development, countries all over the world are actively adjusting their energy structure and vigorously developing renewable energy. Therefore, polycrystalline silicon solar cells have become a hot spot of global concern. Because the improved Siemens method for preparing high-purity polysilicon has a complicated process, high investment costs, chemical principles, and pollution problems, it is more practical to use metallurgy to purify solar-grade polysilicon. [0003] Among them, due to similar physical properties, how to effectively ...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 罗学涛蔡靖李锦堂郑淞生陈文辉沈晓杰龚惟扬陈朝
Owner XIAMEN UNIV
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