CN101497441A - Method for preparing high purity silicon - Google Patents

Method for preparing high purity silicon Download PDF

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Publication number
CN101497441A
CN101497441A CNA2009101270172A CN200910127017A CN101497441A CN 101497441 A CN101497441 A CN 101497441A CN A2009101270172 A CNA2009101270172 A CN A2009101270172A CN 200910127017 A CN200910127017 A CN 200910127017A CN 101497441 A CN101497441 A CN 101497441A
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container
silicon
zinc
purity
high purity
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CN101497441B (en
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大石直明
桥本明
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BEIJING ZHONGJING HUYE TECHNOLOGY CORP
Oishi Naoaki
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BEIJING ZHONGJING HUYE TECHNOLOGY CORP
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Priority to PCT/CN2009/071476 priority Critical patent/WO2010022601A1/en
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/02Silicon
    • C01B33/021Preparation
    • C01B33/027Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/02Silicon
    • C01B33/021Preparation
    • C01B33/027Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/033Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by reduction of silicon halides or halosilanes with a metal or a metallic alloy as the only reducing agents
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01PINDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00Physical properties of inorganic compounds
    • C01P2006/80Compositional purity

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

The invention provides a method of producing high purity silicon. The method produces high purity silicon at low cost on a large scale by complete separation, recovery and reuse of the reaction products. The method comprises the steps of: using a container 1 with temperature maintaining at 910 to 1300 degrees centigrade, a container 2 with temperature maintaining at 300 to 400 degrees centigrade and a container 3 with temperature maintaining less than 0 degree centigrade; the outlet side of the container 3 being connected with external gas by a waste gas treatment device, combing the containers 1, 2, 3 in series, supplying silicon tetrachloride gas, zinc fume and inert gases from the inlet of the container 1; supplying under the state of maintaining the stoichiometric ratio being more than that of zinc under 1000 to 1200 hPa pressure, such that there is no zinc in the system; the container 1 obtains granular silicon; the container 2 obtains byproduct zinc chloride and granular silicon; the container 3 recovers the rest silicon tetrachloride by liquid state. The byproduct zinc chloride of the container 2 is recovered by granular silicon, then sent to aqueous solution to electrolyze; the zinc is recovered and reused.

Description

The manufacture method of high purity silicon
Technical field
The present invention relates to the manufacturing field of silicon, relate in particular to a kind of manufacture method that is used for the high purity silicon of solar cell raw material.
Background technology
High purity silicon generally adopts Siemens Method (siemensprocess) to make as semiconductor device silicon single-crystal raw material.But, high purity silicon is as having the silicon for solar cell monocrystalline of great demand or the raw material of polycrystalline ingot casting from now on, because Siemens Method cost height, in order to make high purity silicon cheaply, now about the various manufacture method beyond the Siemens Method just in motion and even exploitation.
The zinc reduction of one of them, before implementing more than 50 year, once once do not use Siemens Method, 1978 to 1980 afterwards in the Battelle of U.S. Columbus institute (Battelle ColumbusLaboratory), with the cost degradation is purpose, from the by product zinc chloride, reclaim zinc and chlorine by fusion electrolysis, the step that combination is recycled has been implemented this method.Being characterized as of this method (hereinafter referred to as the BCL method): make silicon tetrachloride and zinc as raw material, be directed into Reaktionsofen with vapor state separately, solid phase is separated out granular and even pulverous silicon, by product zinc chloride and unreacted silicon tetrachloride and zinc are carried out Separation and Recovery separately by knockouts (condenser), will in reduction step, utilize again by the resulting zinc of electrolysis of silicon tetrachloride and zinc and zinc chloride.But owing in Reaktionsofen and the knockouts each separating substances not exclusively being produced variety of issue, this method is not by practical application afterwards.
Afterwards, to above-mentioned BCL method, by setting the scope of reduction reaction temperature, or make zinc fume with respect to the mol ratio of the silicon tetrachloride that imports greater than the equivalence ratio of chemical equation etc., thereby the particle diameter and the shape of the silicon that control generates, yield with raising silicon is a purpose, proposed several schemes and applied for a patent (as: with reference to patent documentation 1~6, wherein, patent documentation 1 is a TOHKEMY 2003-34519 communique, patent documentation 2 is a TOHKEMY 2003-95633 communique, patent documentation 3 is a TOHKEMY 2004-18370 communique, patent documentation 4 is a TOHKEMY 2004-210594 communique, patent documentation 5 is a TOHKEMY 2004-284935 communique, patent documentation 6 is a TOHKEMY 2006-290645 communique).Yet these schemes include in the scope of above-mentioned BCL method, for the problem points in the BCL method, promptly resultant of reaction separate fully with each scheme of basic solution that reclaims fully and utilize again in all be not mentioned.
Summary of the invention
The embodiment of the invention provides a kind of manufacture method of high purity silicon, be to solve in the BCL method problem that each separating substances in the Reaktionsofen and knockouts not exclusively can't be carried out the industrialization practicality, can realize the separation fully of resultant of reaction in the BCL method and reclaim fully and utilize again with good productivity, purpose provide can low-cost mass production solar-grade polysilicon manufacture method.
The objective of the invention is to be achieved through the following technical solutions:
The manufacture method of the high purity silicon that the embodiment of the invention provides is specially: form container 1 with heating, insulation, refrigerating function and container 2, with have refrigerating function and have the container 3 that links to each other with ambient atmos through emission-control equipment system at outlet side according to the order series combination of container 1,2,3;
Wherein, make container 1,2,3 temperature maintenance separately 910 to 1300 ℃, 300 to 400 ℃, below 0 ℃, simultaneously from the ingress of container 1, making purity is that rare gas element, silicon tetrachloride gas and the zinc fume of 6N flows to container 1 under 1000 to 1200hPa (hundred handkerchiefs) pressure, and the stoichiometric ratio of keeping silicon tetrachloride is higher than the state of zinc, wherein, the N among the 6N represents in the percentage purity 9 number.
At container 1 the silicon solid phase is separated out, when container 2 makes the cohesion of zinc chloride liquid phase, obtained the micropartical of silicon, make remaining silicon tetrachloride liquid phase cohesion and recovery, and in system, do not comprise the step of separation of Zinc from resultant of reaction at container 3.
In the aforesaid method because the temperature range in the container 1 is 910 to 1300 ℃, so the silicon tetrachloride that boiling point is 907 ℃ zinc and boiling point is 58 ℃ react with gas phase state moment 100%, fusing point be 1414 ℃ silicon then solid phase separate out, be deposited in the inner face of container 1.Afterwards, go into greater than the state downstream of zinc with the stoichiometric ratio of silicon tetrachloride, zinc all consumes in reduction reaction, no longer is present in the later system of container 1.Therefore, in system, there is no need to carry out the step of separation of Zinc from resultant of reaction fully.And, if the equivalence ratio of silicon tetrachloride is many during reduction reaction, unreacted and silicon that residual silicon tetrachloride and reduction generate reacts, the disproportionation reaction of silicon dichloride gas can take place to generate, this is reflected at when surpassing 1352 ℃ under 1 normal atmosphere and can sharply carries out, the temperature of container 1 can suppress this reaction if be controlled at below 1300 ℃.The temperature of container 2 is set at 300 to 400 ℃ scope, this temperature is at the fusing point of zinc chloride more than 283 ℃, boiling point below 732 ℃, and at the boiling point of silicon tetrachloride more than 58 ℃, so make zinc chloride carry out the liquid phase cohesion and the isolating while from the silicon tetrachloride of gas phase, can will be in container 1 generate and generate a part of silicon microparticle that gas is transferred, reclaim by container 2 with the form of outstanding turbid zinc chloride in molten state with reaction.Because silicon tetrachloride by container 2 and rare gas element tie up in the container 3 and maintain below 0 ℃,, rare gas element is discharged into the outside via emission-control equipment so remaining silicon tetrachloride is given the liquid phase cohesion and reclaim.
To carry out drying, the silicon of recovery cake (cake) shape with silicon microparticle filtration, pickling and after washing only with ultra-high purity in the zinc chloride and the silicon microparticle dissolving or outstanding turbid behind highly purified dilution solder(ing)acid of container 2 recovery.As the high density chlorination zinc aqueous solution of filtrate after adjusting concentration, PH, temperature, use aluminium sheet to carry out electrolysis as anode, use ion-exchange membrane as barrier film as negative electrode, use DSE (insoluble electrode), thereby the recovery high-purity Zn is utilized its reductive agent as silicon tetrachloride again.
The technical scheme that is provided by the invention described above embodiment as can be seen, embodiment of the present invention reclaims the granular and even spongiform silicon that is generated after the zinc completely consumed at container 1 (reduction reactor), reclaim zinc chloride and silicon microparticle at container 2 (knockouts one), reclaim silicon tetrachloride at container 3 (knockouts two), do not need to carry out the step of separation of Zinc from resultant of reaction in the system.Zinc chloride and silicon microparticle that container 2 is reclaimed dissolve or hang turbid in high purity dilution solder(ing)acid, filter this solder(ing)acid and reclaim silicon microparticle, and reclaim zinc by electrolysis as the dense solder(ing)acid of filtrate, so can carrying out and separate resultant easily, each separation (recovery) step can reclaim fully by the high purity state.Therefore, this method can realize from the BCL method resultant of reaction being separated fully and reclaiming fully and utilize with good productivity, makes the low-cost volume production of high-purity silicon for solar energy cell become possibility.
Description of drawings
The flow chart of steps of a kind of embodiment that Fig. 1 provides for the embodiment of the invention.
Symbol brief description among the figure:
1-reduction reactor (container 1) 1a-heating, attemperator
1b-refrigerating unit 2-knockouts one (container 2)
2a-heating, attemperator (electric furnace) 2b-possess the tectosome of cooling function
2c-steam trap 3-knockouts two (container 3)
3a-refrigerator 4-emission-control equipment
5-zinc vaporizer 6-silicon tetrachloride vaporizer
7-aqueous solution electrolytic cell 8-dissolving tank.
Embodiment
The embodiment of the invention provides a kind of manufacture method that is used for the high purity silicon of solar cell raw material.Be a kind of with raw material silicon tetrachloride and zinc, import Reaktionsofen with vapor state respectively, solid phase is separated out granular and even pulverous silicon, will be reduced into zinc after the electrolysis of by product zinc chloride and utilizes, promptly so-called gas phase zinc reduction and obtain the manufacture method of high purity silicon.
Understand for convenient, the flow process of the manufacture method of the high purity silicon of 1 pair of embodiment of the invention is described further with reference to the accompanying drawings.
This manufacturing process: adopt container 1 (reduction reactor) and container 2 (knockouts one) to connect and the bonded system according to the order of container 1,2,3 with having refrigerating function and having the container 3 (knockouts two) that links to each other with ambient atmos through emission-control equipment at outlet side with heating, insulation, refrigerating function.And, make container 1,2,3 temperature maintenance separately 910 to 1300 ℃, 300 to 400 ℃, below 0 ℃ in, the rare gas element (argon gas), silicon tetrachloride gas and the zinc fume that from container 1 ingress with purity are 6N are under 1000 to 1200hPa the pressure and keep the stoichiometric ratio of silicon tetrachloride to surpass under the condition of zinc about 3 to 100%, flow to container 1, wherein, N among the 6N (nine) means in the percentage purity 9 number, for example the purity of 6N promptly represents 99.9999%, following synonym).
At first, the pressure in the said system, from preventing the inner and running security aspect of ambient atmos invasive system, must make its maintain near normal pressure and belong to malleation 1000 to 1200hPa.The control of this pressure can be supplied to the feed speed of silicon tetrachloride gas, zinc fume and the rare gas element of container 1 by adjustment, and container 3 outlet side peristomes or container 2 are realized toward the gas flow of the inlet part of containers 3.
Secondly, the reason of silicon tetrachloride gas with respect to the stoichiometric ratio surplus of zinc fume described.Container 1 temperature inside maintains 910 to 1300 ℃ by heating and heat-insulating device 1a and refrigerating unit 1b, this temperature range is that the boiling point of 732 ℃ of the boiling points of 907 ℃ of boiling points, zinc chloride at zinc and silicon tetrachloride is more than 58 ℃, and at the fusing point of silicon below 1414 ℃, the reduction reaction of this moment is as follows.
SiCl 4(gas)+2Zn(gas)→Si(solid)+2ZnCl 2(gas)
By thermodynamic data as can be known, in 910 to 1300 ℃ of the design temperature scopes of container 1, almost moment 100% carries out to be accompanied by the reduction reaction of heat release.If this moment the silicon tetrachloride surplus, during near 1300 ℃ of high temperature, following disproportionation reaction (disproportionation) can take place under 1 normal atmosphere, the silicon of generation is understood some and is become silicon dichloride, but, at last can 100% be converted to silicon in cold zone generation reversed reaction.
Disproportionation reaction Si+SiCl 4→ 2SiCl 2
Therefore, when reacting in the gas stream of silicon tetrachloride surplus, all zn all makes silicon tetrachloride be reduced into silicon effectively, does not contain zinc in the resultant of reaction of airflow downstream fully.So, do not need the separating step of zinc in the system.
In the case, react in order to make zinc 100%, silicon tetrachloride also wants 3% with respect to the excess rate of the stoichiometric ratio of zinc is minimum.And for temperature and the integral pressure with container 1,2,3 maintains in the stable claimed range, this excess rate is with better, but the silicon microparticle that disproportionation reaction and reversed reaction thereof generated that takes place because of the silicon of the silicon tetrachloride of surplus and generation might become many, can cause the utilising efficiency of production unit to reduce simultaneously because of the increase of the silicon tetrachloride internal circulating load in the production equipment system, so the excess rate maximum is suitable with about 100%.From multiple angles, the state flow that surpasses zinc about 3~100% with the stoichiometric ratio of keeping silicon tetrachloride is advisable to container 1.
In addition, above-mentioned disproportionation reaction surpasses 1352 ℃ under 1 normal atmosphere will sharply carry out, and silicon dichloride is reduced to silicon and silicon tetrachloride in that reversed reaction takes place when cryogenic container 2 moves.The silicon that generate this moment is the particulate about 1 micron, also is difficult to use even reclaim, so be necessary to suppress as far as possible this disproportionation reaction.Therefore, under the condition of malleation and silicon tetrachloride surplus, be necessary to keep the temperature of container 1 below 1300 ℃.
On the other hand, with regard to equivalence ratio if make the zinc surplus, this disproportionation reaction will be suppressed (with reference to patent documentation 2), but because of the zinc fume of surplus can and by product zinc chloride vapor and the silicon particle below a part of 10 μ m that swim move to reactor downstream jointly, problem such as stop up even in the BCL method, also can react in the device, therefore be necessary to carry out the separation of zinc, zinc chloride and microsilica.If when particularly the method that reclaims high-purity Zn from zinc chloride, adopting the aqueous electrolysis that is easy to turn round, at first to carry out the separation of zinc according to the vapour pressure deficit of zinc chloride, both boiling points are respectively 907 ℃ and 732 ℃, bigger difference is arranged, so separate very difficult fully on vapour pressure unlike zinc chloride and silicon tetrachloride (58 ℃ of boiling points).And in the mixture of zinc and zinc chloride, sneak under the situation of microsilica, in order to remove microsilica, will be in fusing point high temperature fused state filtration more than 420 ℃ of zinc, perhaps zinc is not directly reclaimed with the state of zinc but in hydrochloric acid, filter again after the dissolving once etc., then will pass through unnecessary step.When containing zinc in the bearing reaction resultant, can't be as in the present invention microsilica be reclaimed easily as goods, the aqueous solution that zinc chloride is used as electrolysis.
Silicon tetrachloride gas and zinc fume be in the control of the feed speed of container 1, and the steam generator 5,6 by separately carries out.The supply of silicon tetrachloride is to drop into liquid silicon tetrachloride in the vaporizer 6 of stainless steel, Yi Bian monitor the generation flow velocity of silicon tetrachloride steam, Yi Bian control the output rating of the electrothermal heater that vaporizer is equipped with, controls its feed speed thus.The zinc of solid or molten state is dropped into the vaporizer 5 of silica glass system, be heated near 907 ℃ of boiling points, the output rating of the electrothermal heater that the liquid level that one side is monitored zinc is simultaneously controlled vaporizer and is equipped with is controlled feed speed.
The internal temperature of relevant container 1 is controlled by following steps.At first, for make the by product zinc chloride all under vapor state downstream the direction of container 2 move, the internal temperature of container 1 will maintain more than the boiling point (910 ℃) of zinc chloride and zinc.On the other hand, the present invention adopts and to move near normal pressure, between the silicon and remaining silicon tetrachloride that is generated after surpassing 1352 ℃, can produce above-mentioned disproportionation reaction, to the direction discharge of container 2.For anti-situation here, near the temperature the outlet of container 1 must be controlled in below 1300 ℃ at least.But this disproportionation reaction can be reduced to silicon and silicon tetrachloride because of reversed reaction once more at the cold zone below 1352 ℃.This reductive silicon can be separated out with the micropartical state, but in the present invention, even the temperature for the moment in the container 1 surpasses 1352 ℃, by the aftermentioned method, also can catch fully in container 2 and reclaims this reduction silicon with the high purity state.
The vapour phase reduction reaction of carrying out in the container 1 is thermopositive reaction, if do not remove reaction heat, even begin reaction with about 900 ℃ temperature, when reaction was carried out, container 1 internal temperature also can rise to more than 1300 ℃.Therefore, for the temperature that keeps container 1 at 910 to 1300 ℃, the leading portion (upstream side) of container 1 is packed among the electric furnace 1a with heating, heat insulation function, back segment (downstream side) is packed among the tectosome 1b with refrigerating function.
It is highly purified granular and even spongy that the silicon that container 1 is reclaimed is generally, may produce the silicon powder of trace during taking-up or sneak into the following impurity micropartical of 0.1 μ m, be to remove the impurity micropartical, take out the weak hydrochloric acid in back from container 1, ultrapure water is clean and carry out drying.
About container 2 (knockouts one), its purpose makes it become liquid phase state for the cohesion zinc chloride, obtains the silicon microparticle that swims of outstanding turbid state simultaneously in the zinc chloride fused solution, separates remaining silicon tetrachloride gas and rare gas element then.For this reason, be configured in the temperature of the zinc chloride liquid receiving portion branch of container 2 bottoms, must be between 732 to 283 ℃.Simultaneously, in order to reduce, must reduce temperature as much as possible from the silicon tetrachloride gas of container 2 discharges and the dividing potential drop of the zinc chloride vapor the rare gas element.Therefore, for the dividing potential drop with zinc chloride vapor drops to below 1hPa, temperature must be controlled at below 400 ℃, preferably 300 ℃, zinc chloride is not solidified.For this reason, pack among 300 to 400 ℃ the electric furnace 2a with heating and heat preserving function in the bottom of container 2.
On the other hand, the top of container 2 (upstream side) packs among the tectosome 2b that possesses refrigerating function, 910 to 1300 ℃ the resultant of reaction of discharging from container 1 can be cooled to 300 to 400 ℃.In addition, when solid phase is separated out and is obtained the zinc chloride vapor of trace, for the refrigerating function that makes container 3 is more effectively brought into play, the exit portion of leading to container 3 at container 2 is provided with steam trap (trap) 2c and silicon tetrachloride gas and rare gas element temperature is cooled to below 150 ℃ (be preferably 70 ℃).
Afterwards, container 3 (knockouts two) liquefies unreacted silicon tetrachloride, Separation and Recovery from rare gas element.For this reason, the vapour pressure of silicon tetrachloride at least will be below 100hPa, and the temperature of container 3 must be preferably subzero below 10 ℃ below 0 ℃.
Another feature of the present invention is: zinc chloride that container 2 is obtained and silicon microparticle dissolving or outstanding turbid behind highly purified rare solder(ing)acid, pie silicon is reclaimed in silicon microparticle filtration, clean, dry back, with the dense solder(ing)acid electrolytic recovery of zinc of this filtrate, utilize again with the reductive agent of zinc as silicon tetrachloride.
From the aqueous solution electrolytic cell 7 of zinc chloride, zinc is reclaimed the thinning electrolytic solution in back deliver to zinc chloride dissolving tank 8, be adjusted to specified zinc oxide concentration, be supplied to electrolyzer 7 once again.This dilution solder(ing)acid is the zinc chloride that is used to dissolution vessel 2.The zinc chloride of container 2 is delivered to dissolving tank 8 behind overcooling, curing schedule, this lysate via the filtering separation silicon microparticle after, carry out after zinc oxide concentration, pH value, temperature etc. adjust, use as the electrolytic solution of electrolyzer 7.
Electrolyzer 7 usefulness aluminium sheets are made negative electrode, are made anode, carry out electrolysis with ion-exchange membrane as barrier film with DSE (insoluble electrode), reclaim zinc.At this moment, if the ultra-high purity water that the water of solder(ing)acid uses semi-conductor to use, just can obtain purity 5N (nine, mean in the percentage purity 9 number, for example the purity of 5N promptly represents 99.999%, following synonym) Yi Shang high-purity Zn will can be used as the zinc fume of required purity 6N (nine) of silicon tetrachloride when reduction and utilizes after its distillation.And the simultaneous chlorine of this electrolysis can liquefy after dehydration and reclaim, as the prepared using of silicon tetrachloride, hydrochloric acid, other mechanicalss.
Comprise above-mentioned BCL method, the method for the patent application of Ti Chuing nearly all adopts with the electrolysis process of fusion electrolysis method as zinc chloride afterwards.Yet, the fusion electrolysis method is compared with the aqueous electrolysis method, though the electric power original unit of electrolyzer may reduce about 20% in theory, but must under 400 to 600 ℃ high temperature, handle, and the fusion electrolysis method also has difficulty and device material in the sealing of by product chlorine that the danger of sneaking into impurity is arranged, and to electrolyzer circulation supply electrolytic solution and the recovery of maintenance electrolyzer, the temperature of attendant equipments such as keeping fused zinc all needs extra thermal source, also exist electrolytic steady running difficult, device working efficiency low problem, thus with use aqueous electrolysis below 100 ℃ to compare to be inferior very much.Therefore, as method, be advisable with the aqueous electrolysis method with the in stable condition recovery zinc of high purity.Among the present invention, biggest advantage is the zinc that does not have remained unreacted in the reduction reaction resultant, so available high purity water dissolved method reclaims zinc chloride at an easy rate.
Secondly, the silicon microparticle that container 2 is obtained because of being generally the particle of 10 to 0.1 μ m, need use the resin system strainer of aperture below 0.1 μ m during filtration.The silicon microparticle surface attachment that filters out from solder(ing)acid has the impurity zinc chloride, use highly purified weak aqueous hydrochloric acid to clean after, after the clean and drying, can obtain the high purity silicon of pie by the ultra-high purity washing again.Thus, add the granular and even spongiform silicon that upper container 1 obtains, the silicon in the raw material silicon tetrachloride can reclaim high purity silicon by the yield more than 95%.
The method that provides according to the invention described above embodiment, the high purity silicon that can be contained free micro mist hardly, and free if desired micro mist is seldom and during bigger finer and closely woven bulk silicon, the silicon impact briquetting that is obtained in available the inventive method is about 10 to 200mm bulk, under vacuum or decompression argon environment, heat-treat at 1300 to 1400 ℃, can obtain the purpose product.The mould that impact briquetting under this situation is used must select for use physical strengths such as silicon nitride to pollute the material of silicon by force and not.Moreover the container that thermal treatment is used must be selected the heat-stable material that also can not pollute silicon under the high temperature such as high-purity carborundum for use.If thermal treatment temp rises to more than the melt temperature of silicon, after then fusion, the curing, need to pulverize, also can bring pollution.Therefore, thermal treatment temp is for being advisable than low slightly 1300 to 1400 ℃ of the fusing point of silicon.
At last, the above purity of 6N (nine) to be arranged at least,, in the complete Separation and Recovery of resultant of reaction,, can not expect that it possesses refining function even the contamination preventing function is arranged according to the method for the embodiment of the invention as high-purity silicon for solar energy cell.So during according to the high purity silicon more than the method manufacturing purity 6N (nine) of the embodiment of the invention, raw material silicon tetrachloride gas, reductive agent zinc fume and the rare gas element that circulates simultaneously all require the above purity of 6N (nine).
In addition, if when containing silicon hydrates such as trichlorosilane, dichlorosilane in the silicon tetrachloride, silicon hydrate in the mixed gas is in the design temperature scope of container 1 of the present invention, all separate out silicon with the zinc fume reduction, become zinc chloride vapor and hydrogen, so as long as the mixed gas purity of using all is applicable to the method for the embodiment of the invention more than 6N.But, when calculating unstripped gas, must use the chemical equivalent of corresponding unstripped gas with respect to stoichiometric excess rate of zinc.
The concentration of silicon hydrate was above 10% o'clock in the silicon tetrachloride gas, for guaranteeing security by the secondary hydrogen of giving birth to and discharging to the external world together from the peristome of container 3 and rare gas element of zinc reduction, need be to be not less than 10 times of hydrogen gas volumes and above air dilution near escape orifice.Like this, the mixed gas of silicon tetrachloride and silicon hydrate is used as raw material, promptly refer to the method for the embodiment of the invention to be made up with a large amount of secondary Siemens Methods of giving birth to same mixed gass and make polysilicon.
The present invention must satisfy above-mentioned condition on the implementation.Relevant other conditions can suitably be selected when satisfying above-mentioned condition.For example, can select container 1 to catch the silicon of separating out the bottom or inner all silicon is separated out for the round tubular of horizontal type for vertical circular tower shape.
For example the structure of container 2 can be made into and is divided into 2 parts, comprise main cooling down high-temperature resultant of reaction part and with the zinc chloride of cohesion with the liquid or solid-state part that retains.The material of the container that uses, the material of utensil and the pipe arrangement that links to each other with container need possess the temperature that contacted and thermotolerance, the erosion resistance of atmosphere gaseous matter, preferably selects the reliable material in other field practicability for use.For example, as general silica glass and the silicon carbide that uses of the thermal treatment of semiconductor material, the silicon nitride or Inconel (registered trademark) and the nickel that use as general heat-resisting, corrosion resistant material, even materials such as the Teflon (registered trademark) that uses of generally acidproof, corrosion-resisting resin, polypropylene, vinylchlorid, when the invention process, can use.
Embodiment one
Container 1 is that internal diameter is that 300mm, length are the carborudum tube of 2500mm, being attached thereto container 2 tops that connect is the carborudum tube of internal diameter 100mm, height 1500mm, the bottom is the nickel container of internal diameter 700mm, degree of depth 1000mm, the container 3 that joins with container 2 bottoms is to use the knockouts two of stainless steel, at container 3 opening that links to each other with the external world via emission-control equipment 4 is set.Container 1 and 2 is equipped with heating, the electrothermal heater 1a of insulation usefulness and the 1b of air cooling mechanism of transport portion air.Can be cooled to subzero water cooler 3a below 10 ℃ in container 3 settings.
With vessel cascade 1,2, after 3 system all uses the above argon replaces of purity 6N (nine), with this argon gas speed that flow 5L/ divides when dropping into to the direction mobile of container 3 simultaneously by container 1, container 1,2,3 temperature is set at 910 ℃ respectively, 300 ℃, subzero 20 ℃, to be preheated to about 400 ℃ and purity afterwards and be the above silicon tetrachloride gas of 6N (nine) and be preheated to about 910 ℃ and purity is the above zinc fume of 6N (nine), keep silicon tetrachloride to the equivalence ratio of zinc at the state that has more 5 to 15%, respectively silicon tetrachloride and zinc divides with average 166.5g/ and average 116.4g/ divides speed were flowed 20 hours by the direction of container 1 to container 3.During this time, the internal pressure of container 1,2,3 remains on 1000 to 1100hPa, control container 1 temperature inside at 910 ℃ to 1300 ℃, the internal temperature of container 2 bottoms at 300 ℃ to 400 ℃, the temperature of container 3 subzero below 10 ℃.
Then, obtain a part from container 1 and be spongiform granular silicon 24kg, obtain containing the zinc chloride 290kg of the microsilica below the 10 μ m from container 2.With zinc chloride and microsilica, dissolve separately and after the suspension pH value is 2, zinc oxide concentration is the high purity chlorination zinc aqueous solution of 10g/L, with polypropylene filter separating particles silicon, after cleaning with 2 centinormal 1 high purity acid, clean with the ultra-high purity washing again, filter with Teflon (registered trademark) strainer, directly carrying out drying under reduced pressure below 90 ℃ then, obtain the pie silicon of 4.8Kg.The purity of the silicon that is obtained by above step has been confirmed all more than 6N (nine).
Embodiment two
In the treatment process of embodiment one, it is that 200g/L, PH are 3, temperature is 30 ℃ that a part of solder(ing)acid behind the separating particles silicon is adjusted to zinc oxide concentration, make negative electrode, make anode (insoluble anode), carry out aqueous electrolysis as barrier film with aluminium then with ion-exchange membrane with DSE, confirmed to drop into reclaiming with the above purity of 5N (nine) more than 95% of the zinc that contains in the electrolytic zinc chloride, in distillation more than 907 ℃, purity is all more than 6N (nine) with it.
Embodiment three
Silicon with granular, the spongy and pie that obtains among the embodiment one, mould with silicon nitride is pressed into the dome-type that diameter is 100mm, in the silicon carbide container, 0.1kPa under the following high purity argon atmosphere, 1400 ℃ carry out thermal treatment in 2 hours after, obtaining not containing fully the diameter that free micro mist and purity almost reaches 7N (nine) is the hemispherical silico briquette of 100mm.
Embodiment four
Mixed gas with the purity 6N (nine) that contains 5% the trichlorosilane of having an appointment in the silicon tetrachloride gas is a raw material, with respect to zinc with equivalence ratio 5 to 15%, supply with according to the speed that the average 164.2g/ branch of mixed gas, the average 114.5g/ of zinc divide, with after method is reacted 10 hours similarly to Example 1, container 1 and container 2 respectively obtain the high purity silicon of 12kg and 2.5kg then.Purity is all more than 6N (nine).
One embodiment of the present invention more than have been described, certainly, the present invention is not limited only to above-mentioned embodiment, also can implement with different modes in each in its technical scope.Make possibility of its application on the concrete industry of the manufacturing of high purity silicon.
In sum, so far also the make silicon tetrachloride and the zinc of practicability import Reaktionsofen and separate out granular and even pulverous silicon with solid phase with vapor state from the improvement of essence ground in the present invention, then pair is given birth to zinc chloride and become zinc and utilization once more by electrolytic reduction, that is so-called zinc reduction (BCL method) according to vapor phase process, can be in industrial application.Thereby, can low cost production 6N (nine) high-purity silicon for solar energy cell of level.
The above; only be the preferable embodiment of the present invention; but protection scope of the present invention is not limited thereto; the present invention is not caused any restriction because of the succession of each embodiment yet; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (5)

1, a kind of manufacture method of high purity silicon is characterized in that, comprising:
The container 1 that employing has heating, insulation, a refrigerating function and container 2, with have refrigerating function and have the container 3 that links to each other with ambient atmos through emission-control equipment at outlet side, according to the system of the order series combination of container 1,2,3;
Wherein, make container 1,2,3 separately temperature maintain 910~1300 ℃ respectively, 300~400 ℃, below 0 ℃, simultaneously from the ingress of container 1, making purity is the rare gas element of 6N, silicon tetrachloride gas and zinc fume are under 1000~1200hPa pressure, and be higher than under the state of zinc in the stoichiometric ratio that keeps silicon tetrachloride, enter container 1, the silicon solid phase is separated out, in container 2, make in the zinc chloride liquid phase cohesion and catch silicon particle, in container 3, make remaining silicon tetrachloride liquid phase cohesion and recovery, wherein, the N among the 6N represents in the percentage purity 9 number.
2, the manufacture method of high purity silicon according to claim 1, it is characterized in that, after zinc chloride that described container 2 reclaims and silicon particle are dissolved in highly purified solder(ing)acid, carry out drying, reclaim the silicon of cake (cake) shape with silicon particle filtration, pickling and after washing only with ultra-high purity; With solder(ing)acid after adjusting concentration, pH value and temperature, with aluminium sheet as negative electrode, insoluble electrode DSE as anode, carry out electrolysis with ion-exchange membrane as barrier film, obtain high-purity Zn, utilize again as the reductive agent of silicon tetrachloride.
3, the manufacture method of high purity silicon according to claim 1 and 2, it is characterized in that, after resulting pie silicon is shaped to 10 to 200mm bulk in resulting granular and even spongy silicon or the described container 2 in the described container 1, in vacuum or decompression argon atmosphere, carry out 1300~1400 ℃ thermal treatment, obtain not having the bulk silicon of free particulate.
4, the manufacture method of high purity silicon according to claim 1, it is characterized in that, the described purity that enters to silicon tetrachloride gas, zinc fume and rare gas element in the container 1 is all greater than more than the 6N (nine), and wherein the N among the 6N represents in the percentage purity 9 number.
5, the manufacture method of high purity silicon according to claim 1, it is characterized in that, the described silicon tetrachloride gas that enters container 1 is to contain the silicon hydrate of trichlorosilane or dichlorosilane and purity is the above mixed gas of 6N, and the stoichiometric ratio of keeping this mixed gas when entering container 1 all the time surpasses the stoichiometric ratio of zinc, and wherein the N among the 6N represents in the percentage purity 9 number.
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