CN102951645A - Method for removing boron and phosphorus impurity in industrial silicon by slagging refining - Google Patents
Method for removing boron and phosphorus impurity in industrial silicon by slagging refining Download PDFInfo
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- CN102951645A CN102951645A CN2012105300484A CN201210530048A CN102951645A CN 102951645 A CN102951645 A CN 102951645A CN 2012105300484 A CN2012105300484 A CN 2012105300484A CN 201210530048 A CN201210530048 A CN 201210530048A CN 102951645 A CN102951645 A CN 102951645A
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- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 73
- 239000010703 silicon Substances 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 49
- 238000007670 refining Methods 0.000 title claims abstract description 32
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 31
- 239000012535 impurity Substances 0.000 title claims abstract description 31
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title claims abstract description 26
- 229910052698 phosphorus Inorganic materials 0.000 title abstract description 15
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title abstract description 11
- 239000011574 phosphorus Substances 0.000 title abstract description 11
- 239000002893 slag Substances 0.000 claims abstract description 100
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 72
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000010439 graphite Substances 0.000 claims abstract description 34
- 239000011248 coating agent Substances 0.000 claims abstract description 20
- 238000000576 coating method Methods 0.000 claims abstract description 20
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 20
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 18
- 229920005591 polysilicon Polymers 0.000 claims abstract description 18
- 238000006243 chemical reaction Methods 0.000 claims abstract description 16
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 claims abstract description 10
- 239000000155 melt Substances 0.000 claims abstract description 9
- 239000002210 silicon-based material Substances 0.000 claims abstract description 8
- 230000006698 induction Effects 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 41
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 34
- 229910004261 CaF 2 Inorganic materials 0.000 claims description 31
- VASIZKWUTCETSD-UHFFFAOYSA-N manganese(II) oxide Inorganic materials [Mn]=O VASIZKWUTCETSD-UHFFFAOYSA-N 0.000 claims description 25
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 22
- 241000209456 Plumbago Species 0.000 claims description 14
- HIVGXUNKSAJJDN-UHFFFAOYSA-N [Si].[P] Chemical compound [Si].[P] HIVGXUNKSAJJDN-UHFFFAOYSA-N 0.000 claims description 14
- 238000013022 venting Methods 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- 229910052786 argon Inorganic materials 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000000280 densification Methods 0.000 claims description 3
- GDFCWFBWQUEQIJ-UHFFFAOYSA-N [B].[P] Chemical compound [B].[P] GDFCWFBWQUEQIJ-UHFFFAOYSA-N 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 19
- 239000003795 chemical substances by application Substances 0.000 abstract description 2
- 238000005273 aeration Methods 0.000 abstract 2
- 230000003068 static effect Effects 0.000 abstract 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 18
- 230000000694 effects Effects 0.000 description 12
- 238000005192 partition Methods 0.000 description 11
- 239000007789 gas Substances 0.000 description 8
- 238000009423 ventilation Methods 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000005272 metallurgy Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000004857 zone melting Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000012159 carrier gas Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000004567 concrete Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052810 boron oxide Inorganic materials 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
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- 239000002131 composite material Substances 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
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- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 1
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- 239000010436 fluorite Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
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- Silicon Compounds (AREA)
Abstract
一种造渣精炼去除工业硅中硼磷杂质的方法，涉及工业硅的除杂工艺。1）在石墨坩埚表面涂上一层致密的SiC涂层作为内层，在SiC涂层上涂覆Y2O3涂层作为外层；2）将造渣剂混合后，放入预处理过的石墨坩埚中；3）打开中频感应炉加热至渣料熔化；4）渣料熔化后向熔化的渣料中加入工业硅，进行造渣精炼，待渣料和硅料完全熔化后，降低功率后反应；5）往熔液中插入通气棒，向体系通入Ar+H2O，确保硅相与渣相接触；6）拔离通气棒，将熔液上层硅液倒到静置的石墨模具中冷却；7）继续添加硅料，重复步骤4）～6）；8）将精炼过多晶硅切除头尾杂质富集部分，再通过ICP-MS测量剩余部分硼磷含量。工艺简单，工业化可行性高。The invention discloses a method for removing boron and phosphorus impurities in industrial silicon through slagging and refining, and relates to the impurity removal process of industrial silicon. 1) Coat a dense SiC coating on the surface of the graphite crucible as the inner layer, and coat the Y 2 O 3 coating on the SiC coating as the outer layer; 2) After mixing the slagging agent, put it into the pretreated 3) Turn on the medium frequency induction furnace and heat until the slag melts; 4) After the slag melts, add industrial silicon to the molten slag for slagging and refining. After the slag and silicon are completely melted, reduce the power Post-reaction; 5) Insert aeration rod into the melt, and pass Ar+H 2 O into the system to ensure that the silicon phase is in contact with the slag phase; 6) Pull out the aeration rod, and pour the silicon liquid on the upper layer of the melt into the static graphite Cool in the mold; 7) Continue to add silicon material, repeat steps 4) to 6); 8) Remove the head and tail impurity-enriched parts of the refined polysilicon, and then measure the boron and phosphorus content of the remaining part by ICP-MS. The process is simple and the industrialization feasibility is high.
Description
Technical field
The present invention relates to the impurity removal process of industrial silicon, especially relate to the method that a kind of slag refining is removed the boron from industrial silicon phosphorus impurities.
Background technology
World today's energy dilemma and environmental pollution pressure are also deposited, and people are badly in need of cleaning, safety, continuable new forms of energy.Sun power always is the target that people pursue as satisfying the energy that requires like this.People are the utilizations of its heat effect to the use of sun power the earliest, but are difficult to satisfy fully the needs of modern society.Until the discovery of photoresistance, the manufacturing of solar cell, people find sun power new utilize mode.Silicon is as the desirable feedstock of solar cell, impurity wherein mainly contains metallic impurity and the nonmetallic impuritys such as B, P such as Fe, A1, Ca, and these impurity elements can reduce the at the interface Compound Degree of photo-generated carrier of silicon crystal grain, and the Compound Degree of photo-generated carrier has determined the photoelectric transformation efficiency of solar cell, in the application facet of solar cell vital effect is arranged so effectively remove these impurity.
Although the polysilicon purity of improvement siemens method preparation is very high, is difficult to the demand that satisfied in recent years photovoltaic industry develops rapidly.1996 under the support of Japanese new forms of energy and industrial technology development organizations, Kawasaki, Japan Inland Steel processed (Kawasaki steel) has developed the method for utilizing metallurgical technology to produce solar-grade polysilicon, this method is significantly improved than Siemens Method at cost and pollution, its main flow process is: selecting general industry silicon is raw material, utilize the boron impurity in the plasma melting removal silicon, the horizontal zone melting directional freeze forms silicon ingot, after removing the end to end part and outer matrix section that metallic impurity are assembled in the silicon ingot, carry out coarse reduction and cleaning; The recycling electron beam melting is removed phosphorus and carbon impurity, carries out horizontal zone melting second time directional freeze and becomes silicon ingot, removes afterwards metallic impurity are assembled in the zone melting and refining silicon ingot second time end to end part and outer matrix section, directly generates solar-grade polysilicon.Alemany etc. (Alemany C, Trassy C, Pateyron B, et al.Refiing of metallurgical grade silicon byinductive plasma[J] .Solar Energy Materials﹠amp; Solar Cells, 2002,72:41-48) utilize electromagnetic induction H
2-O
2Cement Composite Treated by Plasma silicon liquid finds that B content has obvious reduction, and refining effect is obvious, by interpretation and theoretical thermodynamics calculating are found that B mainly removes with the form volatilization of BOH.The plasma body that Japanese Patent No.4-228414 adopts argon gas that mixed gas contains hydrogen and water vapour to form together with SiO 2 powder, the surface of irradiation molten silicon promotes the oxidation removal of boron.The Marvin's meeting (Wu Jijun, Ma Wenhui, Wei Kuixian, et al.Removing boron from metallurgical gradesilicon by vacuum oxidation refining[C] .Proceedings of the 8
ThVacuum Metallurgy and SurfaceEngineering Conference.Shengyang, 2007:51) etc. the people adopt Ar-O
2Plasma body, behind the refining 10min, the B content in the silicon drops to 2ppmw by 40ppmw in 2286～2320K scope.Above technique has all adopted plasma body, and its equipment requirements is high, and melting region is narrow, is blown into the oxidizing gas utilization ratio low, and energy consumption is high during suitability for industrialized production, and current consumption is large, and the treatment time is long, and production cost is high.
C.P.Khattak (Chandra P Khattak, David B Joyce, Frederick Schmid.A simple process toremove boron from metallurgical grade silicon[J] .Solar Energy Mater Solar Cel1s, 2002,74:77) in its paper, point out in silicon liquid, to pass into and contain O, H, the reactant gases of Cl and B reaction generate volatile gases, by carrier gas or the mode that vacuumizes it is discharged from system again, wherein, carrier gas can be selected neutral gas, such as Ar, can play simultaneously promotion silicon liquid and stir, the effect of accelerated reaction.Kondo Jiro etc. (Kondo Jiro, Okazawa Kensuke.Method for removingboron from silicon:US, 20070180949[P] .2007-09-08) have then studied from silicon liquid bottom and have been blown into by Ar, H
2, H
2O and O
2Deng the method for the reactant gases oxidation that forms except B.
In the development of metallurgy method technique subsequently, it is found that and utilize slag practice can remove preferably boron and phosphorus matter in the silicon.US Patent No. 5788945 discloses a method of utilizing the continuous slag making of 60%CaO-40%SiO2 slag former, B content in the raw silicon can be down to 1ppmw from 40ppmw, wherein the slag processing is convection current in a container by slag and silicon, or by two or two convection current that realize slag and molten silicon with upper container.It is SiO that US Patent No. 2008/0241045A1 adopts slag former
2-Na
2CO
3, adopt the mode of slag former recycle under 1600 ℃, B in the silicon is reduced to 0.16ppmw,
According to Tanahashi (Tanahashi, et al.Distribution behavior of boron between SiO2-saturatedNaO
0.5-CaO-SiO
2Flux-molten silicon[J] .J.Mining Mater, 2002, calculating 118:497) etc. is with Na
2O-CaO-SiO
2Be the reaction slag system, the partition ratio of B in slag system can reach 3.5, considers simultaneously in the high alkalinity slag to pass into H
2O can effectively increase the OH in the melt
-With free oxygen concentration, for forming the BOH volatilization and forming B
2O
3Enter slag more favorably condition is provided mutually.The Viana Teixeira of Tokyo Univ Japan and Kazuki Morita (Leandro AugustoViana Teixeira and Kazuki Morital, Removal of Boron from Molten Silicon Using CaO-SiO
2BasedSlags, ISIJIntemational, Vol.49 (2009), No.6, pp.783-787) obtained Different Ca F
2The CaO-SiO of content
2-CaF
2The partition ratio of system and the activity quotient of boron oxide are also found Na simultaneously
2The partition ratio that adds affiliation increase system of O.
Chinese patent CN02135841.9 (a kind of high-purity silicon for solar energy cell and production method thereof) discloses and has a kind ofly added lime in melt, ferric oxide, and the slagging process of fluorite has obtained the high-purity silicon of used for solar batteries.The patent 201010109835.2(Luo Xue of Xiamen University great waves, Gong Weiyang etc., a kind of method that adopts rare earth oxide to remove the boron from industrial silicon phosphorus impurities) in the slag former composition, introduced rare earth oxide, concrete composition is R
XO
Y(Y
2O
3, La
2O
3, CeO
2, Sm
2O
3)-SiO
2-BaO-CaF
2With Medium frequency induction slag making 40min under vacuum, slag silicon weight ratio is 1:1, the B content in the polysilicon can be reduced to 0.15ppmw from 8ppmw, and P content is reduced to 1.5ppmw from 15ppmw.
From the development of following metallurgy method, slag practice is the main method of removing B element in the silicon, and the emphasis of research all is how to improve on the slag gold partition ratio of B now.Selection people for slag former have carried out a lot of trials, and common slag system has CaO-SiO
2, Na
2O-SiO
2, CaO-SiO
2-CaF
2, CaO-MgO-SiO
2, CaO-BaO-SiO
2Deng, these slag systems are having certain effect aspect the removal of B, but there are some inevitable problems in the people aspect industrial production: at first, the removal effect of B is the difficult requirement that reaches solar-grade polysilicon still.Secondly, help the consumption of slag agent relatively too high in the slagging process, limited scale operation, also can produce certain pollution to silicon.And when using CaO slag making system, the content of phosphorus generally higher (at least several ppm, at most tens of ppm) in the slag former often more or less makes phosphorus impurities increase after the refining, increases the difficulty of subsequent process or increases the cost that removal of impurities is purified.
Summary of the invention
The object of the present invention is to provide a kind of slag refining to remove the method for boron from industrial silicon phosphorus impurities.
The present invention includes following steps:
1) the SiC coating that is coated with the last layer densification on the plumbago crucible surface then applies Y in the SiC coating as internal layer
2O
3Coating is as skin;
2) with after the various slag formers mixing, put into pretreated plumbago crucible, described various slag formers are ferric oxide, SiO
2, MnO and CaF
2Described ferric oxide is Fe
2O
3, FeO, Fe
3O
4In a kind of;
3) open medium-frequency induction furnace heating, melt to slag charge;
4) slag charge melts in the slag charge of backward fusing and adds industrial silicon, carries out slag refining, after slag charge and silicon material melt fully, reduces the power afterreaction;
5) in liquation, insert venting pin, pass into Ar+H to system
2O guarantees that the silicon phase contacts with slag;
6) pull away venting pin, liquation upper strata silicon liquid is poured in the graphite jig that leaves standstill, cooling;
7) continue to add silicon material, repeating step 4)～6);
8) refining is crossed polysilicon and excise end to end impurity enriched part, measure remainder boron phosphorus content by ICP-MS again.
In step 1), the thickness of described internal layer can be 1～3mm, and described outer field thickness can be 1～2mm.
In step 2) in, described ferric oxide, SiO
2, MnO and CaF
2Mass percent can be: ferric oxide is that 10%～60%, MnO is 5%～35%, CaF
2Be 10%～30%, surplus is SiO
2Described ferric oxide, SiO
2, MnO and CaF
2Mass percent be preferably: ferric oxide is that 10%～50%, MnO is 5%～30%, CaF
2Be 10%～25%, surplus is SiO
2Described ferric oxide, SiO
2, MnO and CaF
2Mass percent be preferably: ferric oxide is that 10%～40%, MnO is 15%～25%, CaF
2Be 10%～20%, surplus is SiO
2
In step 3), the condition of described heating can be in 1～2h power is added to 120～150kW, and final holding power 120～150kW melts to slag charge.
In step 4), the add-on of described industrial silicon can be in mass ratio: slag former: industrial silicon=(20～26): (5～9), describedly fall lower powered condition and can be in 10～30min and to reduce power to 90～120kW, the temperature of described reaction can be 1550～1850 ℃.
In step 5), described venting pin can be 10～20mm apart from the distance of crucible bottom, described Ar+H
2Among the O, Ar is 60%～90%, H by mass percentage
2O is 40%～10%; The described Ar+H that passes into
2The speed of O can be 0.5～3L/min, the described Ar+H that passes into
2The speed of O is preferably 1～2L/min.
In step 6), described graphite jig can adopt cylindrical graphite jig, and the inside radius of described cylindrical graphite jig can be 15～25cm, and external diameter can be 16～26cm, and height can be 40～50cm; The speed of described cooling can be 100～400 ℃/min, and the speed of cooling is preferably 200～300 ℃/min.
In step 7), described repeating step 4)～6 number of times) can be and is cycled to repeat 5～20 times, is preferably 8～15 times.
In step 8), described excision ratio end to end can be 5%～10%.
The present invention is based on the smelting iron and steel principle, iron oxide based slag system has good effect to dephosphorization, MnO and CaF
2Can effectively increase melt activity, selective oxidation iron (Fe of the present invention
2O
3, FeO
2, FeO
3)-SiO
2-MnO-CaF
2As slag former.According to thermodynamic principles, Fe
2O
3-SiO
2-MnO-CaF
2Reaction equation with B, P in slagging process is as follows:
Fe
2O
3+1.2P＝1.2PO
2.5+2Fe
Usually represent deimpurity ability with partition ratio.
The partition ratio of B is expressed as
Wherein, (mass%B) the B content of expression slag in mutually, [mass%B] expression silicon B content in mutually.The B oxidation products BO that generates as can be known according to phasor
1.5Thereby easily be combined with MnO and improved ferric oxide (Fe
2O
3, FeO
2, FeO
3Deng)-SiO
2-MnO-CaF
2Slag system is to the B oxygenizement, and then improved the B partition ratio.
The partition ratio of P is expressed as
Wherein, (mass%P) the P content of expression slag in mutually, [mass%P] expression silicon P content in mutually.Not only ferric oxide can improve the partition ratio of P and CaF to the oxidation of P in this slag system
2Also can play dephosphorizing and can generate Ca with the oxide compound reaction of phosphorus
5(PO
4)
3Thereby, better improved the removal effect of phosphorus.
But this slag system is in slagging process, along with the increase of iron oxide content, L
pAlso can and then rise, but along with the decline of P content in the silicon, the amount of the ferric oxide of increase can't be all and P reaction, L
pDescend.The increase of simultaneous oxidation iron also can be to SiO
2Activity exert an influence, thereby reduce the clearance of B.Along with SiO
2The increase of content, the system oxygen partial pressure increases, L
BRise gradually, but excessive oxygen partial pressure makes again L
BDescend.Therefore, for ferric oxide-SiO
2-MnO-CaF
2The slag making system is determined suitable ferric oxide/SiO
2/ MnO/CaF
2Most important for the dust removal rate that improves whole system.
Main purpose of the present invention provides the processing method that boron and phosphorus matter in the polysilicon is removed in a kind of slag making.The concrete technology flow process is to prepare by a certain percentage slag charge first, has put it into SiC, Y
2O
3In the plumbago crucible of coating, Frequency Induction Heating adds the industrial silicon material to fusing, and then aeration-agitation after the fusing of silicon material is poured upper strata silicon liquid into graphite and accepted crucible and cool off fast.The general percentage range of each composition in the slag system that the present invention is given, OK range, design parameter scope in optimized scope and the technique, and the technological process cost is low, easy to operate, energy consumption is little, is suitable for suitability for industrialized production.
Advantage of the present invention is to utilize SiO
2, in the time of the golden partition ratio of the raising B slag that the slag system ingredients such as MnO can be larger, utilize ferric oxide in the slag system, CaF
2Better improved the removal effect of P with the interaction of phosphorus, wherein the boron clearance reaches more than 95%, tp removal rate is up to more than 90%, solved the present Ca B such as slag system such as grade of system partition ratio generally lower, and the problems such as the P removal effect is not good only need be carried out directional freeze one procedure after slag making is finished again, just industrial silicon can be purified to solar-grade polysilicon, simple for process, the industrialization feasibility is high.
Embodiment
Embodiment 1
1. the SiC coating that is coated with the last layer densification on the plumbago crucible surface is about 1.5mm as internal layer thickness, then applies Y in the SiC coating
2O
3Coating is about 1mm as outer layer thickness, to increase plumbago crucible work-ing life.
2. weighing Fe
2O
3(10%wt)-SiO
2(60%wt)-MnO (20%wt)-CaF
2(10%wt) slag former is total to 130kg, puts into the graphite of coating.Close bell, open intermediate frequency, the 1h internal power rises to 120kW, keeps power 120kW that slag charge is melted fully.
3. after the slag charge fusing, add 25kg industrial silicon (B content is 8.6ppmw, and P content is 15ppmw).After slag charge and silicon material melt fully, reduce power in the 25min to 90kW, recording this moment temperature of reaction by infrared thermometer is 1550 ℃.
4. pass into mixed gas Ar+H to system
2O, venting pin are apart from crucible bottom 10mm, and wherein the volume fraction of Ar is 60%, H
2The volume fraction of O is 40%.Ventilation Rate 2L/min fully stirs liquation.
5.30min after, pull away venting pin, stop ventilation, liquation upper strata silicon liquid is poured into the graphite that leaves standstill accept in the mould, cool off, the outside radius of the cylindrical graphite jig that this experiment is adopted is 17cm, inside radius is 15cm, and height is 40cm, and the control rate of cooling is at 200 ℃/min.
6. continue in plumbago crucible, to add industrial silicon 25kg, so repeat slag making 8 times.
7. obtain altogether refining polysilicon 170kg, through ICP-MS the gained polysilicon is taken multiple measurements and average, wherein average B content is 0.1ppmw, and mean P content is 0.5ppmw.
Embodiment 2
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 3mm, Y
2O
3External coating (EC) thickness is 1.5mm, wherein adds slag former FeO (10%wt)-SiO
2(60%wt)-MnO (15%wt)-CaF
2(15%wt) be total to 100kg.Open intermediate frequency, in the 1.5h power is risen to 150kW, keep power 150kW that slag charge is melted fully.Then add the 45kg industrial silicon.In the 15min power is reduced to 120kW after the fusing fully, this moment, temperature of reaction was 1650 ℃.Pass into 90%Ar+10%H
2O stirs liquation, and venting pin is about 12mm apart from the distance of crucible bottom, Ventilation Rate 1L/min.After slag making continued 15min, pouring upper strata silicon liquid into outside radius was 22cm, and inside radius is 20cm, and high accepting for the graphite of 50cm cooled off in the mould, and rate of cooling is controlled at 200 ℃/min.Again add the 45kg industrial silicon, altogether add 15 times.Obtain altogether refining polysilicon 573kg.Recording average B content through ICP-MS is 0.25ppmw, and mean P content is 1.5ppmw.
Embodiment 3
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 1mm, Y
2O
3External coating (EC) thickness is that 2mm adds slag former Fe
3O
4(15%wt)-SiO
2(60%wt)-MnO (10%wt)-CaF
2(15%wt) be total to 100kg.Open intermediate frequency, in the 1.2h power is risen to 130kW, keep power 130kW that slag charge is melted fully.Then add the 35kg industrial silicon.In the 15min power is reduced to 110kW after the fusing fully, this moment, temperature of reaction was 1750 ℃.Venting pin is 14mm apart from the distance of crucible bottom, Ventilation Rate 1.5L/min.After slag making continued 20min, pouring upper strata silicon liquid into outside radius was 20cm, and inside radius is 18cm, and high accepting for the graphite of 45cm cooled off in the mould, and rate of cooling is controlled at 300 ℃/min.Again add the 35kg industrial silicon, altogether add 10 times.Obtain altogether refining polysilicon 212kg.Recording average B content through ICP-MS is 0.12ppmw, and mean P content is 0.7ppmw.
Embodiment 4
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 3mm, Y
2O
3External coating (EC) thickness is that 1mm adds slag former Fe
2O
3(20%wt)-SiO
2(60%wt)-MnO (10%wt)-CaF
2(10%wt) be total to 130kg.Open intermediate frequency, in the 2h power is risen to 150kW, keep power 150kW that slag charge is melted fully.Then add the 45kg industrial silicon.In the 20min power is reduced to 120kW after the fusing fully, this moment, temperature of reaction was 1850 ℃.Venting pin is 17mm apart from the distance of crucible bottom, passes into 80%Ar+20%H
2O stirs liquation, Ventilation Rate 1L/min.After slag making continued 20min, pouring upper strata silicon liquid into outside radius was 20cm, and inside radius is 18cm, and high accepting for the graphite of 45cm cooled off in the mould, and rate of cooling is controlled at 300 ℃/min.Again add the 45kg industrial silicon, altogether add 9 times.Obtain altogether refining polysilicon 345kg.Recording average B content through ICP-MS is 0.15ppmw, and mean P content is 0.8ppmw.
Embodiment 5
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 2mm, Y
2O
3External coating (EC) thickness is that 2mm adds slag former Fe
3O
4(10%wt)-SiO
2(50%wt)-MnO (20%wt)-CaF
2(20%wt) be total to 120kg.Open intermediate frequency, in the 1.5h power is risen to 150kW, keep power 150kW that slag charge is melted fully.Then add the 45kg industrial silicon.In the 15min power is reduced to 120kW after the fusing fully, this moment, temperature of reaction was 1850 ℃.Venting pin is that 15mm passes into 60%Ar+40%H apart from the distance of crucible bottom
2O stirs liquation, Ventilation Rate 2L/min.After slag making continued 30min, pouring upper strata silicon liquid into outside radius was 20cm, and inside radius is 18cm, and high accepting for the graphite of 45cm cooled off in the mould, and rate of cooling is controlled at 200 ℃/min.Again add the 30kg industrial silicon, altogether add 10 times.Obtain altogether refining polysilicon 255kg.Recording average B content through ICP-MS is 0.12ppmw, and mean P content is 0.8ppmw.
Embodiment 6
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 2.5mm, Y
2O
3External coating (EC) thickness is that 1mm adds slag former FeO (10%wt)-SiO
2(50%wt)-MnO (20%wt)-CaF
2(20%wt) be total to 110kg.Open intermediate frequency, in the 2h power is risen to 150kW, keep power 150kW that slag charge is melted fully.Then add the 45kg industrial silicon.In the 20min power is reduced to 110kW after the fusing fully, this moment, temperature of reaction was 1750 ℃.Venting pin is that 19mm passes into 70%Ar+30%H apart from the distance of crucible bottom
2O stirs liquation, Ventilation Rate 2L/min.After slag making continued 20min, pouring upper strata silicon liquid into outside radius was 20cm, and inside radius is 18cm, and high accepting for the graphite of 45cm cooled off in the mould, and rate of cooling is controlled at 300 ℃/min.Again add the 35kg industrial silicon, altogether add 12 times.Obtain altogether refining polysilicon 357kg.Recording average B content through ICP-MS is 0.2ppmw, and mean P content is 1.2ppmw.
Embodiment 7
Technological process is with embodiment 1.Plumbago crucible SiC undercoat thickness is 2mm, Y
2O
3External coating (EC) thickness is that 1.5mm adds slag former Fe
2O
3(20%wt)-SiO
2(40%wt)-MnO (15%wt)-CaF
2(15%wt) be total to 130kg.In the 2h power is risen to 150kW, keep power 150kW that slag charge is melted fully.Then add the 45kg industrial silicon.In the 20min power is reduced to 110kW after the fusing fully, this moment, temperature of reaction was 1750 ℃.Venting pin is that 20mm passes into 90%Ar+10%H apart from the distance of crucible bottom
2O stirs liquation, Ventilation Rate 2L/min.After slag making continued 15min, pouring upper strata silicon liquid into outside radius was 20cm, and inside radius is 18cm, and high accepting for the graphite of 45cm cooled off in the mould, and rate of cooling is controlled at 200 ℃/min.Again add the 30kg industrial silicon, altogether add 15 times.Obtain altogether refining polysilicon 383kg.Recording average B content through ICP-MS is 0.18ppmw, and mean P content is 1ppmw.
Claims (10)
1. a slag refining is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that may further comprise the steps:
1) the SiC coating that is coated with the last layer densification on the plumbago crucible surface then applies Y in the SiC coating as internal layer
2O
3Coating is as skin;
2) with after the various slag formers mixing, put into pretreated plumbago crucible, described various slag formers are ferric oxide, SiO
2, MnO and CaF
2Described ferric oxide is Fe
2O
3, FeO, Fe
3O
4In a kind of;
3) open medium-frequency induction furnace heating, melt to slag charge;
4) slag charge melts in the slag charge of backward fusing and adds industrial silicon, carries out slag refining, after slag charge and silicon material melt fully, reduces the power afterreaction;
5) in liquation, insert venting pin, pass into Ar+H to system
2O guarantees that the silicon phase contacts with slag;
6) pull away venting pin, liquation upper strata silicon liquid is poured in the graphite jig that leaves standstill, cooling;
7) continue to add silicon material, repeating step 4)～6);
8) refining is crossed polysilicon and excise end to end impurity enriched part, measure remainder boron phosphorus content by ICP-MS again.
2. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 1), and the thickness of described internal layer is 1～3mm, and described outer field thickness is 1～2mm.
3. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 2) in, described ferric oxide, SiO
2, MnO and CaF
2Mass percent be: ferric oxide is that 10%～60%, MnO is 5%～35%, CaF
2Be 10%～30%, surplus is SiO
2Described ferric oxide, SiO
2, MnO and CaF
2Mass percent be preferably: ferric oxide is that 10%～50%, MnO is 5%～30%, CaF
2Be 10%～25%, surplus is SiO
2Described ferric oxide, SiO
2, MnO and CaF
2Mass percent be preferably: ferric oxide is that 10%～40%, MnO is 15%～25%, CaF
2Be 10%～20%, surplus is SiO
2
4. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 3), the condition of described heating is for adding to power 120～150kW in 1～2h, final holding power 120～150kW melts to slag charge.
5. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 4), and the add-on of described industrial silicon is in mass ratio: slag former: industrial silicon=(20～26): (5～9).
6. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 4), describedly fall lower powered condition for reduce power to 90～120kW in 10～30min, the temperature of described reaction is 1550～1850 ℃.
7. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 5), and described venting pin is 10～20mm apart from the distance of crucible bottom, described Ar+H
2Among the O, Ar is 60%～90%, H by mass percentage
2O is 40%～10%; The described Ar+H that passes into
2The speed of O can be 0.5～3L/min, the described Ar+H that passes into
2The speed of O is preferably 1～2L/min.
8. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 6), described graphite jig adopts cylindrical graphite jig, and the inside radius of described cylindrical graphite jig is 15～25cm, external diameter is 16～26cm, and height is 40～50cm; The speed of described cooling can be 100～400 ℃/min, and the speed of cooling is preferably 200～300 ℃/min.
9. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 7) described repeating step 4)～6) number of times can be and be cycled to repeat 5～20 times, be preferably 8～15 times.
10. a kind of slag refining as claimed in claim 1 is removed the method for boron from industrial silicon phosphorus impurities, it is characterized in that in step 8), and described excision ratio end to end is 5%～10%.
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