Method for smelting and purifying backing material of monocrystalline pot by electron beams

An electron beam smelting and single crystal technology, applied in chemical instruments and methods, inorganic chemistry, non-metallic elements, etc., can solve the problems of low minority carrier life of polycrystalline silicon ingots, achieve high production efficiency, increase minority carrier life, and short production cycle Effect

Inactive Publication Date: 2017-08-04
DALIAN UNIV OF TECH QINGDAO NEW ENERGY MATERIALS TECH RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the high concentration of metal impurities in the single crystal pot bottom material, the polycrystalline silicon ingot produced by using it has a low minority carrier life.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] A method for purifying single crystal pot bottom material by electron beam smelting, specifically comprising the following steps:

[0018] A. Loading: Load the single crystal pot bottom material into the silo, melting crucible, feeding trolley, and five solidification crucibles, among which 500kg is loaded into the silo, 65kg is loaded into the melting crucible, and 45kg is loaded into the feeding trolley , put 15kg into five solidified crucibles, the purity of silicon in the single crystal pot bottom material is 4.5N, the content of P is 3ppmw, the total metal content is 45ppmw, the content of Fe is 15ppmw, the content of Al is 9ppmw, the content of Ca is 4ppmw, and the content of other metals is less than 1ppmw ;

[0019] B. Preheating electron guns: After the charging is completed, the electron beam furnace is evacuated, and when the vacuum degree is less than 0.5 Pa, start to preheat 3 electron guns, of which 2 electron guns irradiate the melting crucible, and the o...

Embodiment 2

[0026] Each step of the method for a kind of electron beam smelting purification single crystal bottom material described in the present embodiment is all the same as in Embodiment 1, and different technical parameters are:

[0027] 1) In step A, 550kg of single crystal pot bottom material is loaded into the silo, 60kg of heavily arsenic-doped silicon material is loaded into the melting crucible, 40kg of heavily arsenic-doped silicon material is loaded into the feeding trolley, and 550kg of heavy arsenic-doped silicon material is loaded into the melting crucible. The heavy arsenic-doped silicon material loaded separately is 10kg; the purity of the silicon material in the single crystal pot bottom material is 5.5N, the P content is 2.5ppmw, the total metal content is 40ppmw, the Fe content is 10ppmw, the Al content is 8.5ppmw, and the Ca content is 3.5ppmw;

[0028] 2) In step B, the electron gun is preheated for 20 minutes;

[0029] 3) Melting the silicon material for 10 minut...

Embodiment 3

[0032] The steps of a method for removing impurity arsenic in silicon by electron beam smelting described in this embodiment are all the same as in Embodiment 1, and the different technical parameters are:

[0033] 1) In step A, 600kg of single crystal pot bottom material is loaded into the feed bin, 70kg of heavily arsenic-doped silicon material is loaded into the melting crucible, 50kg of heavily arsenic-doped silicon material is loaded into the feeding trolley, and 50kg of heavy arsenic-doped silicon material is loaded into the melting crucible. The heavy arsenic-doped silicon material loaded separately is 20kg; the purity of the silicon material in the single crystal pot bottom material is 5.0N, the P content is 2.0ppmw, the total metal content is 35ppmw, the Fe content is 9ppmw, the Al content is 8.0ppmw, and the Ca content is 3.0ppmw;

[0034] 2) In step B, the electron gun is preheated for 40 minutes;

[0035] 3) Melting the silicon material for 30 minutes in step C;

...

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Abstract

The invention relates to a method for smelting and purifying backing material of a monocrystalline pot by electron beams. The method comprises the following steps of respectively charging the backing material of the monocrystalline pot into a material bin, a smelting crucible, a material delivery cart and five condensing crucibles; after material charging is completed, sucking vacuum out of an electron beam furnace, and preheating three electron guns when the vacuum degree is smaller than 0.5Pa; enabling the power of each of the three electron guns to continue to maintain for 250kW, and smelting silicon material; closing two electron guns which radiate to the smelting crucibles, pouring out the silicon liquid, and maintaining the power of the electronic gun radiating the condensing crucible to 250kW after the pouring is finished; finally, enabling the electron guns to maintain for 10min at the power of 250kW, 2min at the power of 200kW, 3min at the power of 150kW, 5min at the power of 120kW, 7min at the power of 100kW, 10min at the power of 80kW, 15min at the power of 50kW, 20min at the power of 30kW, and 25min at the power of 20kW, and condensing the electron beams at the power of 0kW. The method has the advantages that the metal impurities can be effectively removed, the removal rate reaches 98% or above, and the minority carrier lifetime in the produced polycrystalline cast ingot can be effectively prolonged; the condition is mild, and the operation is easy.

Description

technical field [0001] The invention belongs to the technical field of electron beam smelting, in particular to a method for purifying single crystal pot bottom material by electron beam smelting. Background technique [0002] The monocrystalline pot bottom material produced by Czochralski monocrystalline silicon rods in the industry contains a relatively high concentration of metal impurities. At present, due to the continuous increase in the investment of solar cells, the demand for silicon materials is increasing, and the reuse of single crystal pot bottom materials is also continuing. However, due to the presence of high-concentration metal impurities in the single crystal pot bottom material, the polycrystalline silicon ingot produced by using it has a low minority carrier life. Therefore, there is a need for a method that can effectively remove metal impurities in the single crystal pot bottom material. Contents of the invention [0003] The purpose of the present ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 姜大川孟剑雄王峰李鹏廷姚玉杰
Owner DALIAN UNIV OF TECH QINGDAO NEW ENERGY MATERIALS TECH RES INST CO LTD
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