Method and equipment for directional solidification and purification of polycrystalline silicon through taking tailing by quartz tube

A directional solidification, quartz tube technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of reduced industrial production costs, high cutting equipment costs, affecting purification effects, etc. Energy consumption and the effect of reducing process links

Inactive Publication Date: 2013-03-20
QINGDAO NEW ENERGY SOLUTIONS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the subsequent slow cooling process, the impurities in the high-concentration area will diffuse to the low-concentration area, so that the purity of silicon will gradually decrease with the prolongation of the holding time, which affects the purification effect, and in this case, the tail that needs to be removed The waste is as high as 25%~35%, and the finished product rate is only 65-75%
At the same time, due to the relatively high hardness of silicon, h

Method used

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  • Method and equipment for directional solidification and purification of polycrystalline silicon through taking tailing by quartz tube

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Such as figure 1 The equipment used in the method of directional solidification and purification of polysilicon by taking tailings from quartz tubes is shown. The outer wall is composed of a vacuum chamber 2, and a vacuum pipeline 16 is installed on the outer wall. One end of the vacuum pipeline 16 is connected to a vacuum pump group 15.

[0024] A ventilation pipeline 13 is fixedly installed on the outer wall, and a tailings collection box 14 is installed movably. The water cooling plate 12 is movably installed at the bottom of the vacuum chamber 2. The graphite plate 11 is placed on the top of the water cooling plate. One end of the pillar 10 is nested and connected to the graphite plate 11 through a hole, and the other end is nested and connected to the graphite tray 9. The crucible 7 is placed on the graphite tray 9, and the graphite heating element 6 is set on the periphery of the crucible and fixed on the side wall of the vacuum chamber 2. , 4 sets of carbon felt ...

Embodiment 2

[0029] Use the equipment described in Example 1 to take the tailings and carry out directional solidification to purify polysilicon. First, add silicon material with a purity of 99.5% to the crucible 7 with 90% of the volume of the crucible, close the ventilation line 13, and turn on the vacuum pump group 15. The vacuum degree in the vacuum chamber 2 is pumped to 10Pa, close the vacuum pump group 15, open the ventilation pipeline, fill the vacuum chamber 2 with 99.92% argon until the pressure reaches 100Pa, and close the ventilation pipeline;

[0030]The second step of smelting and solidification: turn on the power, use the induction coil 5 and the graphite heating element 6 to heat the silicon material in the crucible 7 to 1450 ° C until it is completely melted into a silicon melt, keep it at this temperature for 30 minutes, and pull it vertically downward The water cooling plate 12 makes the silicon melt in the crucible 7 move vertically downward at a constant speed at a spee...

Embodiment 3

[0033] Use the equipment described in Example 1 to take tailings and carry out directional solidification to purify polysilicon. First, add silicon material with a purity of 99.7% to the crucible 7 with a volume of 93% of the crucible, close the ventilation line 13, and turn on the vacuum pump group 15. The vacuum in the vacuum chamber 2 is pumped to 2 Pa, the vacuum pump group 15 is closed, the ventilation pipeline is opened, and the vacuum chamber 2 is filled with argon gas with a purity of 99.94% until the pressure reaches 2000 Pa, and the ventilation pipeline is closed;

[0034] The second step of smelting and solidification: turn on the power, use the induction coil 5 and the graphite heating element 6 to heat the silicon material in the crucible 7 to 1550 ° C until it is completely melted into a silicon melt, keep it at this temperature for 45 minutes, and pull it vertically downward The water cooling plate 12 makes the silicon melt in the crucible 7 move vertically downw...

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Abstract

The invention belongs to the technical field of metallurgy purification, and particularly relates to a method and equipment for directional solidification and purification of polycrystalline silicon through taking tailing by a quartz tube. According to the method, under inert gas environment, silicon is melt and then is cooled to pull ingot; when solidification is completed by 85-90%, the quartz tube is stretched into the surplus melt silicon, vacuumizing is stopped, inert gas is led in, the surplus melt silicon enters the quartz tube under the action of pressure difference, ingot pulling is continuously carried out, after the upper end of a crucible leaves a heating area, a tailing collection box is stretched below the quartz tube with a point; the power is cut off so as to stop heating, melt silicon in the quartz tube expands, then the quartz tube cracks and falls into the tailing collection box, and cast ingot of high purity in the crucible is obtained. Due to the method, back-diffusion of impurity is prevented, technology processes are reduced, and the yield of cast ingot is improved. The equipment is convenient to improve and install, is simple to operate, can effectively remove impurities accumulated at the tail of the cast ingot, save production period and cost, and is applicable to industrial production.

Description

technical field [0001] The invention belongs to the technical field of metallurgical purification, and in particular relates to a method and equipment for directional solidification and purification of polysilicon by tailing material extraction. Background technique [0002] The purification of silicon raw materials is an important link in the solar photovoltaic industry chain. The rapid development of the photovoltaic industry depends on high-efficiency and low-cost purification methods. Directional solidification technology has been widely used in many fields of metal purification, and has achieved remarkable results. In the process of purifying silicon raw materials, metal impurities whose segregation coefficient is far less than 1 will be enriched in the liquid phase during the directional solidification process and finally removed. This method is one of the key links in the current metallurgical preparation of solar-grade polysilicon, and is the most effective method f...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 谭毅安广野顾正张晓峰
Owner QINGDAO NEW ENERGY SOLUTIONS
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