CN102725228A - Method for manufacturing solar-grade silicon - Google Patents

Method for manufacturing solar-grade silicon Download PDF

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Publication number
CN102725228A
CN102725228A CN2010800034173A CN201080003417A CN102725228A CN 102725228 A CN102725228 A CN 102725228A CN 2010800034173 A CN2010800034173 A CN 2010800034173A CN 201080003417 A CN201080003417 A CN 201080003417A CN 102725228 A CN102725228 A CN 102725228A
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walk
silicon
solar energy
energy level
production technology
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刘荣隆
郑敏
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Solar Energy & Materials Incorporate Ltd
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Solar Energy & Materials Incorporate Ltd
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/037—Purification
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)

Abstract

A method for manufacturing solar-grade silicon is disclosed, which comprises the following steps: selecting metallurgical-grade silicon with a purity of no less than 98-99.5% wherein the content of boron element is less than 50ppm and the content of phosphorus element is less than 100ppm; extracting boron and phosphorus in the liquid form from molten silicon at the elevated temperature; solidifying the molten silicon into an ingot; pulverizing the ingot and grinding; corroding the surface; washing by water and drying; removing boron by plasma at elevated temperature; refining in vacuum at elevated temperature so as to remove phosphorus, aluminum and calcium; performing unidirectional solidification and post-treating. In the polycrystalline silicon ingot, the content of boron is less than 0.06ppm, the content of phosphorus is less than 0.01ppm, the whole metal content is less than 0.01ppm, and its resistivity is more than 1.0 Ocm. For manufacturing a solar cell wafer, when it is cut directly into pieces, a photo-electron conversion efficiency of no less than 15% can be achieved; when it is cut into pieces after being pulled into single crystals, a photo-electron conversion efficiency of no less than 16% can be achieved, furthermore, when it is cut into pieces after being pulled into single crystals by means of zone-melting method, a photo-electron conversion efficiency of no less than 17% can be achieved.

Description

Method for manufacturing solar-grade silicon
The present invention relates to a kind of production technology for being used to manufacture solar energy level silicon for a kind of technical field of producing for manufacturing solar energy level silicon of specification.
At present, the manufacture of international monocrystalline or polycrystalline Foundry Works solar level silicon raw material, according to
Remarks：TMI is total metal contents in soil
Initial silicon suitable for solar purposes is to use semiconductor grade silicon（The % of purity ＞ 99. 999999999) end to end material, the silicon material of flavoring food grade one-level.With the developing in solar cell market, the consumption of solar power silicon is greatly increased, and semiconductor secondary material can not meet the growing demand of solar cell industry.The appearance of improved Siemens, alleviates the demand of solar power silicon to a certain extent, but improved Siemens still can not break away from the problems such as the with high investment of traditional Siemens Method, high energy consumption, high pollution.
WACKER companies in 1975 take the lead in employing the Physical Metallurgy method for being different from Siemens Method completely.The development of more than 30 years is passed through in countries in the world, and Physical Metallurgy method can accomplish that metal contains Measure the 01ppm of ＜ 0. level, cost is also greatly less than improved Siemens, but, conventional invention to phosphorus, boron the two have the control of the constituent content of most important effect limited solar energy photoelectric conversion efficiency rate of decay, minority carrier life time, the best phosphorus of the Physical Metallurgy method having been reported that at present, Boron contents are about between 0. l lppm, cause the finished product of Physical Metallurgy method only to be expected mostly with improved Siemens finished product or semiconductor secondary after mutually mixing, the production of solar cell could be used for.
Patent CN1543436A describes one kind and removes boron using plasma, metal is gone to manufacture the high purity silicon for solar cell with directional solidification again, a kind of gaseous mixture of and argon gas composition in its plasma source of the gas chlorine, fluorine, hydrochloric acid, hydrofluoric acid gas, the 250ppm of HIGH-PURITY SILICON content of impurities 100, the 2ppm of Boron contents 0. 5 that its process results is obtained.The technique not only purify it is limited in one's ability, moreover, plasma source of the gas high toxicity used, highly corrosive, very harmful to equipment and operating personnel.
Patent CN100444410C describes p-type solar-grade polysilicon preparation technology, its refining section is before this in oxygen blast, float and electromagnetic centrifugal technology is used after slag, make metal impurities along radius distribution, bombard dephosphorization with electron gun under vacuo again, reorientation solidifies, obtain the % of 99. 9999 % of purity 99. 99999, the 08ppm of boron 0., the lppm of phosphorus 0. HIGH-PURITY SILICON, but the technique is due to lacking effective removal to boron element, cause to select and contact in the equipment choosing of silicon material in raw material to require that Ι Π Α races constituent content have to be lower than 0. lppm harsh conditions, make to be very restricted in its practical application.
Patent PCT/JP96/02965 describes a kind of manufacture method of solar-grade polysilicon, and removing metal impurities, blowing refining using vacuum dephosphorization, directional solidification goes boron carbon oxygen and plasma-arc to deoxygenate the technology of SiClx.The technique can obtain the 3ppm of phosphorus 0., the 6ppm of boron 0., carbon lOppm polysilicon.The technique has directional solidification twice, and 30 % of excision cancel every time, i.e. the silicon material of at least 51 % is wasted in production.
Patent US5510095 describes a kind of production technology of HIGH-PURITY SILICON ingot casting, using plasma Ingot casting is continuously purified with zone melting method, this method exists several clearly disadvantageous：
1) require that feedstock grade is higher, iron 150ppm, aluminium 150ppm.
2) charging rate is slow (2kg/hr), maintains two Walk meltings and a plasma energy consumption too high.
3) exclude impurity not detach effectively so that unfavorable to industrialized production with the continuation impurity content Zhu Walk increases of production, it is impossible to relatively large continuous production.
4) except effect of boron is less desirable, 0. 2ppm can only be dropped to.
5) product is made polysilicon solar cell photoelectric transformation efficiency and there was only 13 %.The content of the invention is it is an object of the invention to provide a kind of production technology for being used to manufacture solar energy level silicon, and the technique can go out environmental protection, low cost, the HIGH-PURITY SILICON for being used directly for silicon solar cell production of high-quality with industrial mass production.
In order to reach above-mentioned purpose, solution of the invention is：
It is a kind of to be used to manufacturing the production technology of solar energy level silicon, Yi Yi Xia Walk manufactured suddenly：Mono- Walk, metalluragical silicon selection：Purity is selected in 98 99. 5 more than % metallurgical grade metallic silicon, boron content ＜ 50ppm, phosphorus element content ＜ 100ppm;
Bis- Walk, high-temperature liquid state extraction：Metalluragical silicon is delivered into intermediate frequency furnace, melting puts into extractant 1, while being passed through gas, extract the boron in silicon liquid, extractant 2 is put into, while being passed through the phosphorus that gas extraction goes out in silicon liquid；
Tri- Walk, silicon liquid solidification：Solidification ingot casting is poured out after silicon liquid is removed slag；
Tetra- Walk, crushing grinding：After silicon ingot is cooled down, first machinery is broken into diameter ＜ 150mm silico briquette, then attrition grinding is into the silica flour of 5 mesh to 500 mesh；
Wu Walk, sheet erosion：Silica flour is put into reactor, chemical etching agent, stirring is added； Liu Walk, washing and drying：By the silica flour after etch, cleaned 2-20 times with deionized water, after dehydration, dry drying；
Qi Walk, high-temperature plasma removal of impurities：Silica flour will be dried to be placed in crucible, with resistance or sensing heating, after melting, boron is removed with flame passes strike liquid surface；
Ba Walk, high-temperature vacuum refining：Silicon liquid is moved into vacuum refining furnace, vacuum refining dephosphorization, aluminium and calcium is carried out；
Jiu Walk, unidirectional solidification：Silicon liquid is placed in crucible, and is put into unidirectional solidification stove, ingot casting is solidified；
Shi Walk, post processing：By the skin cut of the impurity enriched of silicon ingot, solar-grade silicon ingot is obtained.
Wherein, bis- Walk extractant 1, extractant 2 are two or more the mixtures in the compound of calcium, magnesium, sodium, aluminium, iron and silicon.
Bis- Walk extractant 1, the addition sequence of extractant 2 can be exchanged.
Bis- Walk extractant 1 and extractant 2 is that, in 1,450 1800 °C of inputs, extractant can disposably put into, can also repeatedly put into batches in melt temperature, and the reaction time after input is 10 300 minutes every time.
Bis- Walk gas refers to one or more gaseous mixtures in the gases such as oxygen, nitrogen, water vapour, hydrogen, argon gas.
Tri- Walk silicon liquid solidification time as used in 1600 °C are cooled to 1400 °C is 0. 55 hours.
Wu Walk chemical etching agent refers to one or more mixtures such as nitric acid, hydrochloric acid, hydrofluoric acid, acetic acid, sulfuric acid；Or refer to one or more mixtures such as sodium hydroxide, potassium hydroxide, ammoniacal liquor, sodium carbonate；Either two many progress etches of class thing matter point Walk.
Wu Walk sheet erosion is, in 15 95 °C of temperature, to be carried out under normal pressure. The temperature of 7th Walk melting silicon liquids is maintained between 1,420 1800 °C.
It is that immigration plasma heating furnace is obtained after independent resistance furnace or sensing stove heat are melted that 7th Walk, which melts silicon liquid, or direct directly heated on plasma heating furnace with sensing or resistance melts acquisition.
7th Walk plasma source of the gas is using two or more gaseous mixtures such as nitrogen, hydrogen, argon gas, helium, oxygen, vapor.
The 7th Walk preferred argon gas+water vapour of plasma source of the gas, the volume basis ratio of wherein water vapour is 0 50 %.
The Qi Walk plasma refining time is 5 200 minutes.
Qi Walk plasma refining uses single stove to refine, or is connected or many plasma guns series connection continuous refinings of single stove with many stoves.
The temperature of the silicon liquid of Ba Walk vacuum refining is maintained between 1,414 2000 °C.The silicon liquid of Ba Walk vacuum refining is that remelting is obtained again after Qi Walk silicon liquid solidification ingot casting, or Qi Walk silicon liquid is directly moved into vacuum refining furnace acquisition.
The vacuum of Ba Walk vacuum drying oven can be 0. 00001 10Torr.
The refining time of Ba Walk vacuum drying oven is 0. 5 24 hours.
Ba Walk vacuum refining uses single stove or many stoves series connection continuous refining.
Qi Walk plasma removal of impurities is He the order of Ba Walk high-temperature vacuum refining can be exchanged.Jiu Walk unidirectional solidification is to solidify from lower to upper, and setting rate is 2 40mm/ hours.After such scheme, the present invention is by common metal silicon purifying solar energy level polysilicon, the technique makes boron be reduced to 0. below 5ppm by the way of being extracted when refining initial using high-temperature liquid state, phosphorus is reduced to below lppm, so that selecting more wide spectrum in the raw material of industrial silicon, directional solidification ablation technique is replaced metal impurities is reduced to below lOOppm by the way of solidification+sheet erosion, reduce the waste of silicon material, more stoves are created in terms of vacuum dephosphorization and plasma remove boron, the technology of many plasma gun series connection, so that Boron contents are reduced to 0. below 06ppm, Phosphorus content is reduced to 0. below Olppm, finally makes TMKO. Olppm with directional solidification again, obtains the solar-grade polysilicon of high-quality.
The polycrystal silicon ingot that the present invention is obtained, the 06ppm of boron ＜ 0., the Olppm of phosphorus ＜ 0., TMKO. Olppm, Ω-the cmo of the resistivity ＞ 1. 0 solar-grade polysilicon direct slicings are used to manufacture solar battery sheet, can obtain 15 more than % photoelectric transformation efficiency；Cut into slices after pulling of crystals for manufacturing solar battery sheet, 16 more than % photoelectric transformation efficiency can be obtained；Cut into slices after zone melting method crystal-pulling for manufacturing solar battery sheet, 17 more than % photoelectric transformation efficiency can be obtained.Brief description of the drawings Fig. 1 is the process chart of the present invention.Embodiment
Embodiment 1
Coordinate shown in Fig. 1, production technology is：
Mono- Walk, select metalluragical silicon 200kg, and impurity content is：Iron 1819ppm, aluminium 982ppm, beggar 186ppm , Pity 40ppm , Code 15ppm.
Bis- Walk, high-temperature liquid state extraction：Metalluragical silicon is delivered into induction furnace, 1600 °C of meltings put into extractant 1:Calcium, aluminium, silicon systems compound 100kg, while being passed through nitrogen oxygen atmosphere 15L/min, reaction time 80min is repeated once operation, extracts the boron in silicon liquid, and Boron contents are reduced to 1. 03ppm;
1600 °C of molten conditions, then put into extractant 2:Silico-calcium compound 50kg, while being passed through nitrogen 15L/min, reaction time 60min extracts the phosphorus in silicon liquid, and phosphorus content is reduced to 3. 16ppm。
Tri- Walk, silicon liquid solidification：Solidification ingot casting is poured out after silicon liquid is removed slag, speed is；1400 °C of 2 hours used times are reduced to from 1600 °C.
Tetra- Walk, crushing grinding：After cast silicon ingot is cooled down, first machinery is broken into diameter ＜ 150mm silico briquette, then attrition grinding is into the silica flour of 250 mesh to 500 mesh.
Wu Walk, sheet erosion：Silica flour is put into reactor, first add the hydrochloric acid that mass percentage concentration is 6%, in 80 °C of stirring reactions 20 hours, filtering, after being cleaned with deionized water, add the sodium hydroxide that mass percentage concentration is 4% and the sodium carbonate mixed liquor that mass percentage concentration is 5%, in 15 °C of stirring reactions 1 hour, then the nitric acid that mass percentage concentration is 9% and the hydrofluoric acid mixed solution that mass percentage concentration is 13% are added, in 25 °C of stirring reactions 16 hours, sheet erosion Jin mono- Walk removed boron, phosphorus, iron, aluminium and calcium.
Liu Walk, washing and drying：By the silica flour after etch, cleaned with deionized water 10 times, after dehydration, drying is dried, Boron contents are reduced to 0. 54ppm, and phosphorus content is reduced to 0. 91ppm, iron content is reduced to 60. 8ppm, and aluminium content is reduced to 7. 9ppm, and calcium content is reduced to 15. 6ppm.
Qi Walk, high-temperature plasma removal of impurities：Silica flour will be dried to be placed in crucible, with resistance or sensing heating, after melting, 1500 °C of melt temperature, using single stove list plasma gun, source of the gas：Hydrogen, argon gas and water vapour mixing, hit liquid surface 30 minutes with flame passes, remove boron, Boron contents are reduced to 0. 05ppmo
Ba Walk, high-temperature vacuum refining：Silicon liquid is moved into vacuum refining furnace, the series connection of three stoves, carry out vacuum refining, every stove 1 hour, 1500 °C of melt temperature, the Torr of vacuum ＜ 0. 0001, dephosphorization, aluminium and calcium to the equal O l ppm o of ＜ 0. of content
Jiu Walk, unidirectional solidification：Silicon liquid is placed in crucible, and is put into unidirectional solidification stove, ingot casting, setting rate 10mm/ hours is solidified.
Shi Walk, post processing：By the skin cut of the impurity enriched for the silicon ingot cast, excision ratio Example：Along the 15% of solidification direction Bottoming height, solar-grade silicon ingot 79kg, impurity iron, aluminium, calcium, the phosphorus equal Olppm of ＜ 0., the 05ppm of boron 0. are obtained.Embodiment 2
Coordinate shown in Fig. 1, production technology is：
Mono- Walk, select metalluragical silicon 200kg, and impurity content is：Iron 1819ppm, aluminium 982ppm, beggar 186ppm , Pity 40ppm , Code 15ppm.
Bis- Walk, high-temperature liquid state extraction：Metalluragical silicon is delivered into induction furnace, 1600 °C of meltings put into extractant 1:Calcium, aluminium, silicon systems compound 60kg, while being passed through nitrogen oxygen atmosphere 15L/min, reaction time 60min is operated in triplicate, extracts the boron in silicon liquid, and content is reduced to 1. 13ppm;
1600 °C of molten conditions, then put into extractant 2:Silico-calcium compound 25kg, while being passed through nitrogen 15L/min, reaction time 60min repeats secondary operation, extracts the phosphorus in silicon liquid, phosphorus content is reduced to 2. 05ppmo
Tri- Walk, silicon liquid solidification：Solidification ingot casting is poured out after silicon liquid is removed slag, speed is；1400 °C of 2 hours used times are reduced to from 1600 °C.
Tetra- Walk, crushing grinding：After cast silicon ingot is cooled down, first machinery is broken into diameter ＜ 150mm silico briquette, then attrition grinding is into the silica flour of 250 mesh to 500 mesh.
Wu Walk, sheet erosion：Silica flour is put into reactor, first add the hydrochloric acid that mass percentage concentration is 10 %, in 80 °C of stirring reactions 16 hours, filtering, after being cleaned with deionized water, add the sodium oxide molybdena that mass percentage concentration is 5 %, in 15 °C of stirring reactions 1. 5 hours, filtering, cleaned with deionized water, then it is that 3 % nitric acid and mass percentage concentration are 8 % hydrofluoric acid mixed solution to add mass percentage concentration, in 25 °C of stirring reactions 20 hours, filtering, cleaned with deionized water, it is eventually adding the acid that mass percentage concentration is 6 %, in 80 °C of stirring reactions 20 hours, sheet erosion Jin mono- Walk remove boron, phosphorus, iron, aluminium and calcium. Liu Walk, washing and drying：By the silica flour after etch, cleaned with deionized water 10 times, after dehydration, drying is dried, Boron contents are reduced to 0. 52ppm, and phosphorus content is reduced to 0. 74ppm, iron content is reduced to 30. 8ppm, and aluminium content is reduced to 4. 9ppm, and calcium content is reduced to 8. 5ppm.
Qi Walk, high-temperature plasma removal of impurities：Silica flour will be dried to be placed in crucible, with sensing heating, after melting, 1500 °C of melt temperature, using single stove list plasma gun, source of the gas：Argon gas and vapor mixing, hit liquid surface 30 minutes with flame passes, remove boron, Boron contents are reduced to
0. 06ppm。
Ba Walk, high-temperature vacuum refining：Silicon liquid is moved into vacuum refining furnace, single stove, carry out vacuum refining, 2 hours, 1500 °C of melt temperature, the 0001Torr of vacuum ＜ 0., dephosphorization, aluminium and calcium, phosphorus, aluminium and the equal 01ppm of ＜ 0. of calcium content.
Jiu Walk, unidirectional solidification：Silicon liquid is placed in crucible, and is put into unidirectional solidification stove, ingot casting, setting rate 10mm/ hours is solidified.
Shi Walk, post processing：By the skin cut of the impurity enriched for the silicon ingot cast, ratio is cut off：Along 15 % of solidification direction Bottoming height, solar-grade silicon ingot 77kg, impurity iron, calcium, the phosphorus equal Olppm of ＜ 0., the 06ppm of boron 0. are obtained.Embodiment 3
Coordinate shown in Fig. 1, production technology is：
Mono- Walk, select metalluragical silicon 200kg, and impurity content is：Iron 1819ppm, aluminium 982ppm, beggar 186ppm, phosphorus 40m, boron 15pm.
Bis- Walk, high-temperature liquid state extraction：Metalluragical silicon is delivered into induction furnace, 1600 °C of meltings put into extractant 1:Calcium, magnesium, silicon systems compound 140kg, while being passed through nitrogen oxygen atmosphere 15L/min, reaction time 60min extracts the boron in silicon liquid, and Boron contents are reduced to
1. 23ppm;
1600 °C of molten conditions, then put into extractant 2:Silico-calcium compound 25kg, is passed through simultaneously Nitrogen 15L/min, reaction time 60min, are repeated twice operation, extract the phosphorus in silicon liquid, and phosphorus content is reduced to 2. 32ppm0
Tri- Walk, silicon liquid solidification：Solidification ingot casting is poured out after silicon liquid is removed slag, speed is：1400 °C of 2 hours used times are reduced to from 1600 °C.
Tetra- Walk, crushing grinding：After cast silicon ingot is cooled down, first machinery is broken into diameter ＜ 150mm silico briquette, then attrition grinding is into the silica flour of 250 mesh to 500 mesh.
Wu Walk, sheet erosion：Silica flour is put into reactor, first add the hydrochloric acid that mass percentage concentration is 9 %, in 80 °C of stirring reactions 14 hours, filtering, after being cleaned with deionized water, add the potassium hydroxide that mass percentage concentration is 4%, in 15 °C of stirring reactions 40 minutes, filtering, cleaned with deionized water, then the acetic acid that mass percentage concentration is 4% is added, mass percentage concentration is that 10 % nitric acid and mass percentage concentration are 12 % hydrofluoric acid mixed solution, in 25 °C of stirring reactions 14 hours, sheet erosion Jin mono- Walk remove boron, phosphorus, iron, aluminium and calcium.
Liu Walk, washing and drying：By the silica flour after etch, cleaned with deionized water 10 times, after dehydration, drying is dried, Boron contents are reduced to 0. 73ppm, and phosphorus content is reduced to 0. 85ppm, iron content is reduced to 76. 2ppm, and aluminium content is reduced to 3. 8ppm, and calcium content is reduced to 13. 9ppm.
Qi Walk, high-temperature plasma removal of impurities：Silica flour will be dried to be placed in crucible, with sensing heating, after melting, 1500 °C of melt temperature, using single stove list plasma gun, source of the gas：Nitrogen, argon gas and vapor mixing, hit liquid surface 20 minutes with flame passes, remove boron, Boron contents are reduced to 0. 05ppmo
Ba Walk, high-temperature vacuum refining：Silicon liquid is moved into vacuum refining furnace, single stove, carry out vacuum refining, 2 hours, 1500 °C of melt temperature, the OOOlTorr of vacuum ＜ 0., dephosphorization, aluminium and calcium, calcium, the aluminium content equal Olppm of ＜ 0., the 01ppm of phosphorus content 0..
Jiu Walk, unidirectional solidification：Silicon liquid is placed in crucible, and is put into unidirectional solidification stove, is coagulated Gu ingot casting, setting rate 10mm/ hours.
Shi Walk, post processing：By the skin cut of the impurity enriched for the silicon ingot cast, ratio is cut off：Along 15 % of solidification direction Bottoming height, solar-grade silicon ingot 81kg, impurity iron, the calcium equal Olppm of ＜ 0., the Olppm of phosphorus 0., the 05ppm of boron 0. are obtained.

Claims (19)

  1. Claims
    1st, it is a kind of to be used to manufacture the production technology of solar energy level silicon, it is characterised in that Yi Yi Xia Walk manufactured suddenly：
    Mono- Walk, metalluragical silicon selection：Purity is selected in 98 99. 5 more than % metallurgical grade metallic silicon, boron content ＜ 50ppm, phosphorus element content ＜ 100ppm;
    Bis- Walk, high-temperature liquid state extraction：Metalluragical silicon is delivered into intermediate frequency furnace, melting puts into extractant 1, while being passed through gas, extract the boron in silicon liquid, extractant 2 is put into, while being passed through the phosphorus that gas extraction goes out in silicon liquid；
    Tri- Walk, silicon liquid solidification：Solidification ingot casting is poured out after silicon liquid is removed slag；
    Tetra- Walk, crushing grinding：After silicon ingot is cooled down, first machinery is broken into diameter ＜ 150mm silico briquette, then attrition grinding is into the silica flour of 5 mesh to 500 mesh；
    Wu Walk, sheet erosion：Silica flour is put into reactor, chemical etching agent, stirring is added；
    Liu Walk, washing and drying：By the silica flour after etch, cleaned 2-20 times with deionized water, after dehydration, dry drying；
    Qi Walk, high-temperature plasma removal of impurities：Silica flour will be dried to be placed in crucible, with resistance or sensing heating, after melting, boron is removed with flame passes strike liquid surface；
    Ba Walk, high-temperature vacuum refining：Silicon liquid is moved into vacuum refining furnace, vacuum refining dephosphorization, aluminium and calcium is carried out；
    Jiu Walk, unidirectional solidification：Silicon liquid is placed in crucible, and is put into unidirectional solidification stove, ingot casting is solidified；
    Shi Walk, post processing：By the skin cut of the impurity enriched of silicon ingot, solar-grade silicon ingot is obtained.
    2nd, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, its It is characterised by：Bis- Walk extractant 1, extractant 2 are two or more the mixtures in the compound of calcium, magnesium, sodium, aluminium, iron and silicon.
    3rd, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Bis- Walk extractant 1, the addition sequence of extractant 2 can be exchanged.
    4th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that:Bis- Walk extractant 1 and extractant 2 is that, in 1,450 1800 ° of 0 input, extractant is disposably put into melt temperature, or is repeatedly put into batches, and the reaction time after input is 10 300 minutes every time.
    5th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Bis- Walk gas refers to one or more gaseous mixtures in oxygen, nitrogen, water vapour, hydrogen, argon gas.
    6th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Tri- Walk silicon liquid solidification time as used in 1600 °C are cooled to 1400 °C is 0. 55 hours.
    7th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Wu Walk chemical etching agent refers to one or more mixtures in nitric acid, hydrochloric acid, hydrofluoric acid, acetic acid and sulfuric acid；Or refer to one or more mixtures in sodium hydroxide, potassium hydroxide, ammoniacal liquor and sodium carbonate；Either two many progress etches of class thing matter point Walk.
    8th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Wu Walk sheet erosion is 15 95 °C, is carried out under normal pressure.
    9th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The water content ＜ 3% of the dried silica flours of Liu Walk.
    10th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The temperature of 7th Walk melting silicon liquids is maintained between 1,420 1800 °C.
    11st, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, its It is characterised by：It is that immigration plasma heating furnace is obtained after independent resistance furnace or sensing stove heat are melted that 7th Walk, which melts silicon liquid, or direct directly heated on plasma heating furnace with sensing or resistance melts acquisition.
    12nd, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：7th Walk plasma source of the gas uses two or more the gaseous mixture in nitrogen, hydrogen, argon gas, helium, oxygen and vapor.
    13rd, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The 7th Walk preferred argon gas+water vapour of plasma source of the gas, the volume basis ratio of wherein water vapour is 0 50 %.
    14th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The Qi Walk plasma refining time is 10 200 minutes.
    15th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Qi Walk plasma refining uses single stove to refine, or is connected or many plasma guns series connection continuous refinings of single stove with many stoves.
    16th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The temperature of the silicon liquid of Ba Walk vacuum refining is maintained between 1,414 2000 °C.
    17th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The silicon liquid of Ba Walk vacuum refining is that remelting is obtained again after Qi Walk silicon liquid solidification ingot casting, or Qi Walk silicon liquid is directly moved into vacuum refining furnace acquisition.
    18th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The vacuum of Ba Walk vacuum drying oven can be 0. 00001 10Torr.
    19th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：The refining time of Ba Walk vacuum drying oven is 0. 5 24 hours.
    20th, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, its It is characterised by：Ba Walk vacuum refining uses single stove or many stoves series connection continuous refining.
    21st, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Qi Walk plasma removal of impurities is He the order of Ba Walk high-temperature vacuum refining can be exchanged.
    22nd, a kind of production technology for being used to manufacture solar energy level silicon as claimed in claim 1, it is characterised in that：Jiu Walk unidirectional solidification is to solidify from lower to upper, and setting rate is 2 40mm/ hours.
CN2010800034173A 2010-11-22 2010-11-22 Method for manufacturing solar-grade silicon Pending CN102725228A (en)

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