Method and equipment for purifying polycrystalline silicon by melting in electron beam shallow pool

A technology of shallow melting pool and electron beam, which is applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc. It can solve the problems of unfavorable popularization of solar cells, difficult processing of silicon round rods, and large investment in equipment to achieve removal effect Good effect of improving energy utilization rate and simple equipment structure

Inactive Publication Date: 2011-07-20
DALIAN LONGTIAN TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the improved Siemens method and silane method require large equipment investment, high cost, serious pollution, and complicated processes, which are not conducive to the popular application of solar cells. In comparison, the metallurgical method has the characteristics of short production cycle, low pollution, and low cost. The focus of R&D in various countries
Electron beam smelting is one of the important methods for metallurgical purification of polysilicon. It can effectively reduce the impurity phosphorus in polysilicon. However, most of the current methods for

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  • Method and equipment for purifying polycrystalline silicon by melting in electron beam shallow pool
  • Method and equipment for purifying polycrystalline silicon by melting in electron beam shallow pool

Examples

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Embodiment 1

[0024] A method for smelting and purifying polysilicon in an electron beam shallow melting pool. First, a large high-phosphorus and high-metal polysilicon ingot to be purified is placed on a water-cooled lifting tray, and then the top of the silicon ingot is melted by an electron beam, and the molten silicon melt A shallow molten pool is formed in the space formed by the top of the silicon ingot, the water-cooled copper sleeve and the graphite sleeve. After melting for a certain period of time, the impurity phosphorus is removed, and then the water-cooled lifting tray is raised, and the low-phosphorus silicon melt passes through the guide after the liquid level rises. The orifice flows into the quartz crucible, and the ingot is pulled down under the action of heat preservation for directional solidification and growth. Metal impurities are enriched to the top of the silicon ingot. After solidification, the top of the silicon ingot is cut off to remove metal impurities, and final...

Embodiment 2

[0026] A kind of equipment for smelting and purifying polysilicon in an electron beam shallow melting pool. The equipment consists of a vacuum cover 18 and a vacuum furnace wall 2 to form a vacuum equipment. The inner cavity of the vacuum equipment is a vacuum chamber 3; A collar is installed on the 13, and the collar is made of a water-cooled copper sleeve 16 and a graphite collar, the water-cooled copper sleeve 16 is installed on the smelting support base 14, the graphite collar 4 is placed on the water-cooled copper sleeve 16, and the smelting support base is equipped with The water-cooled lifting tray 13 has a diversion port 5 on one side of the graphite collar, and an ingot pulling mechanism is installed under the diversion port. The ingot pulling mechanism adopts the ingot support base 10 and the water-cooled ingot rod 12 to be installed at the bottom of the vacuum furnace wall 2 , the thermal insulation sheath 9 and the graphite heating element 8 are installed on the ing...

Embodiment 3

[0028] Adopt the equipment described in embodiment 2 to carry out the method for smelting and purifying polysilicon by electron beam shallow melting pool, its specific steps are as follows:

[0029]The first step of material preparation: lower the water-cooled lifting tray 13 to the bottom of the smelting support base 14, and then place large high-phosphorus and high-metal silicon ingots 15 with a phosphorus content of 0.0025% and a total metal impurity content of 0.015% on the water-cooled lifting tray 13 On top, the top of the high-phosphorus, high-metal silicon ingot 15 should be level with the upper surface of the graphite collar 4, and the vacuum cover 18 should be closed;

[0030] In the second step pretreatment, the vacuum is extracted, and the vacuum chamber 3 is pumped to a low vacuum of 7Pa with a mechanical pump 20 and a Roots pump 21, and then the vacuum chamber 3 is pumped to a high vacuum of 0.0018Pa with a diffusion pump 22; Cooling water is passed into the lift...

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Abstract

The invention belongs to the field of purification of polycrystalline silicon by adopting a physical metallurgy technology, and discloses a method for purifying polycrystalline silicon by melting in an electron beam shallow pool. The method comprises the following steps of: putting a large high-phosphorus and high-metal polycrystalline silicon ingot needing to be purified on a water-cooled elevating tray; melting the top of the silicon ingot by adopting electron beams; making a molten silicon solution form the shallow pool in a space formed by the top of the silicon ingot, a water-cooled copper sheathing and a graphite ferrule; melting for a certain period of time to remove phosphorus impurity; lifting the water-cooled elevating tray; raising the liquid level of a low-phosphorus silicon melt and making the low-phosphorus silicon melt flow into a quartz crucible through a diversion port; pulling the ingot downwards under the action of heat preservation; performing directional solidification growth; enriching metal impurities towards the top of the silicon ingot; cutting the top of the silicon ingot after solidifying; and removing the metal impurities. By adopting the method, phosphorus and metal impurities in silicon are removed by melting in the electron beam shallow pool and directional solidification, the purity of polycrystalline silicon meets the using requirement of solargrade silicon and energy sources are saved. The method has the advantages of simple process and high production efficiency, and is suitable for batch production.

Description

technical field [0001] The invention belongs to the technical field of purifying polysilicon by physical metallurgy technology, and particularly relates to a method for removing impurity phosphorus and metal in polysilicon; in addition, the invention also relates to its equipment. Background technique [0002] Solar-grade polysilicon material is an important raw material for solar cells. Solar cells can convert solar energy into electrical energy. In today's shortage of conventional energy sources, solar energy has great application value. At present, the world-wide preparation of polysilicon materials for solar cells has formed large-scale production and the main technical routes under development are: [0003] (1) Improved Siemens method: The Siemens method uses hydrochloric acid (or hydrogen, chlorine gas) and metallurgical grade industrial silicon as raw materials to perform hydrogen reduction from trichlorosilane. Now the relatively mature technology in foreign countri...

Claims

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Application Information

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IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 谭毅战丽姝姜大川顾正邹瑞洵
Owner DALIAN LONGTIAN TECH
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