KR20100099396A - Apparatus and method for refining of high purity silicon - Google Patents

Apparatus and method for refining of high purity silicon Download PDF

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Publication number
KR20100099396A
KR20100099396A KR1020090017866A KR20090017866A KR20100099396A KR 20100099396 A KR20100099396 A KR 20100099396A KR 1020090017866 A KR1020090017866 A KR 1020090017866A KR 20090017866 A KR20090017866 A KR 20090017866A KR 20100099396 A KR20100099396 A KR 20100099396A
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South Korea
Prior art keywords
molten metal
flux
crucible
furnace
silicon
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KR1020090017866A
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Korean (ko)
Inventor
백광선
이상철
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미리넷실리콘(주)
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Priority to KR1020090017866A priority Critical patent/KR20100099396A/en
Publication of KR20100099396A publication Critical patent/KR20100099396A/en

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    • 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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/34—Arrangements for circulation of melts
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/367—Coil arrangements for melting furnaces

Abstract

PURPOSE: The removal rate of impurity can get speed and the impurities of many amounts can be eliminated easier. Provided is the high purity silicon purifier and purification process. CONSTITUTION: A high purity silicon purifier comprises the melting furnace(10) capable of vacuum. With the crucible(11) which is arranged as melting in and accepts the silicon of the powder or the pellet state. With the induction heat method(12) which is installed in the around crucible and in which the one-way mixing occurs. With the rotor(13) for being arranged as melting as outside and throwing in the argon gas or flux within crucible.

Description

High Purity Silicon Purifier and its Purification Method {Apparatus and Method for Refining of High Purity Silicon}

The present invention is to obtain a high-purity silicon that can be used in solar cells, more specifically, a high-purity silicon purification device for more effectively removing metal impurities, boron (B), phosphorus (P) and the like contained in low-purity silicon And a purification method thereof.

In general, silicon used in solar cells is required to have a purity of 6N (Six Nines) or more, and most metal impurities are 0.1 ppm or less, and boron (B) and phosphorus (P) are at least 1 ppm or less. desirable.

Silicon satisfying such conditions is known for semiconductors manufactured by the Siemens method, but since the manufacturing method is quite expensive and the purity is higher than necessary, researches on metallurgical methods for solar cells have been actively conducted in recent years. It is becoming.

It is well known that the unidirectional coagulation of metal silicon generally purifies high purity silicon on the solid side due to segregation of the metal impurities in the molten metal, but boron (B) has a high segregation index value, which is not easy to remove by directional coagulation. .

In addition, a method of removing the low boiling point impurities in the molten silicon while the molten silicon is maintained in a vacuum state using a vacuum dissolving method is well known. The vacuum dissolving method removes phosphorus (P), carbon impurities, and the like. There have been many attempts to remove the boron because it is not suitable for removing boron (B).

That is, a slag made of CaF 2 + CaO + SiO 2 is added to the molten silicon to remove the boron using a distribution ratio of boron, or a mist is added to the molten silicon to remove boron. The method of changing the components of slag to remove boron is also shown.

In addition, there is a method of removing boron by contacting the oxidizing gas to the molten silicon, but since the boron concentration is relatively high and metal impurities are not constantly removed, production conditions have not been stabilized yet.

This is not a problem of flux or gas added to remove various impurities, but how impurities in molten silicon and added flux, gas or vacuum will react with impurities in molten silicon. Problems are being derived.

Moreover, since the conventional slag refining technique is a method of refining only by contacting slag with molten silicon, this method requires not only a large amount of flux to be used as slag, but also a contact between impurities and flux in molten silicon. There is a disadvantage that it takes a lot of time.

As a technique for removing boron from metal silicon as described above, Japanese Unexamined Patent Application Publication No. Hei 4-228414 discloses, for example, metal silicon as a raw material is kept in a container in which silica or silica-containing refractory is mainly contained inside. A method of vaporizing and removing boron as an oxide by spraying a hot, high speed plasma jet on a hot water surface is disclosed.

In this technique, since a silica film is formed on the molten surface, there is a drawback that the amount of water vapor added to the plasma jet can only be up to 10%. Therefore, the removal rate of boron is slower than expected and the processing time is long, so that the productivity of silicon does not increase as expected.

In Japanese Unexamined Patent Publication No. 4-193706, molten silicon is dissolved in a silica container having a blower that blows gas into the bottom, and an inert gas such as argon is blown through the blower to stir the melted silicon to melt the silicon. Although a method of removing boron by reacting boron and oxygen in the inside is disclosed, this method requires a long time to reach the target boron concentration because of the slow removal rate of boron.

In Japanese Patent Laid-Open No. 5-139713, a blowhole (membrane) is formed to blow gas into the bottom of the container, and through this, a mixed gas of an inert gas and an oxidizing gas is blown to intensify stirring to remove boron. It is proposed to speed up, but there is a limit on the flow rate of the gas to be blown through the tuyere, and when the gas stops blowing, because the molten metal flows back into the tuyere can not stop the operation in the middle There was a problem with workability.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and an object of the present invention is to reduce the concentration of impurities in low purity silicon, particularly metal impurities and boron, to purify the flux to a purity that can be used for solar cell substrates. The present invention provides a high-purity silicon purifier and a method of purifying the gas which react directly with impurities in the molten metal so that the reaction between the impurities in the molten silicon and the flux or the gas reaction can be quickly and easily removed.

In addition, another object of the present invention is to directly inject the flux, mist, etc. in the molten metal and improve the flowability of the molten metal by unidirectional stirring caused by induction heating, so as to remove the impurities in a large amount of impurities much easier It is to provide a high-purity silicon purification apparatus that can remove a lot and a purification method thereof.

In addition, another object of the present invention is to maintain a high vacuum at a high temperature to easily remove the phosphorus (P) and at the same time to perform the stirring by physical force compared to the conventional mechanical agitation by stirring It is to provide a high-purity silicon purification apparatus and a purification method thereof that can prevent contamination.

The high purity silicon purifying apparatus according to the present invention for achieving the above object is a melting furnace capable of vacuum, a crucible disposed in the melting furnace for accommodating silicon in powder or pellets, and installed around the crucible and stirring in one direction. An induction heating means for causing this to occur, a rotor disposed to the outside of the melting furnace to inject argon gas or flux into the crucible, and a chamber for pushing the argon gas or flux into the distribution pipe in the rotor by internal pressure. It is characterized by.

In addition, the high-purity silicon refining method according to the present invention is charged with 400 to 600 kg of silicon molded into a powder or pellet in a crucible and vacuum-treated to make the inside of the melting furnace 10 -2 to 10 -4 torr while heating by induction heating means. In the vacuum atmosphere, the temperature in the furnace is maintained at 1700 to 1800 ° C. for 50 to 70 minutes, and argon gas is blown into the furnace to lower the temperature of the molten metal to 1400 to 1600 ° C. in the chamber. Pouring 80 ~ 120kg of the flux into the surface of the molten metal or the molten metal through the distribution pipe in the rotor, maintaining the flux for 50 to 70 minutes while all the flux enters the molten metal, and sufficiently reacting the mist through the distribution pipe of the rotor. Pushed into the reactor to react with boron in the melt, and after the rotor was removed from the melt By tilting in the Ar atmosphere, characterized by comprising the step of performing a directional solidification was poured into a clot that want to separate Ar atmosphere conditions.

Here, the induction heating means is characterized in that the molten metal and the additives are mixed by the convection action by one-way stirring while the molten metal held in the crucible is heated in a vacuum.

In addition, the flux may be used by mixing any one or two or more of oxides such as SiO 2 , CaO, CaF 2 , Al 2 O 3 , MgO, and the proportion of the flux is 15 to 30% of the molten metal. It is done.

In addition, after the flux is poured into the molten metal is characterized in that it further comprises the step of maintaining for 50 to 70 minutes while rotating the molten metal by induction heating means.

According to the high-purity silicon purifier and the purification method of the present invention having the characteristics as described above, the flux or gas reacts directly with impurities in the molten metal so that the reaction between the impurities in the molten silicon and the flux or the gas reaction can be performed more quickly and easily. Thus, it is possible to purify the high purity silicon from which all impurities are removed.

In addition, since one-way agitation generated by induction heating method after directly introducing flux and mist into the molten metal improves the fluidity of the molten metal, not only the removal rate of impurities but also much more impurities can be removed. will be.

In addition, since the inside of the furnace can maintain a high vacuum at a high temperature of at least 10 -3 torr and 1700 ° C or higher, not only boron but also phosphorus can be easily removed, and agitation by physical force can be performed as compared with conventional mechanical agitation. It is possible to purify the high purity silicon that can prevent contamination by stirring.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, Figure 1 is a view for explaining a high-purity silicon purification apparatus according to the present invention, this purification apparatus is a vacuum (melting furnace 10) and the silicon disposed in the melting furnace 10 is molded in a powder or pellet state ( The crucible 11 which accommodates Si) is provided.

Induction heating means 12 is installed around the crucible 11, and a rotor 13 is disposed outside the melting furnace 10 so that argon gas or flux can be introduced into the crucible 11. have.

That is, a chamber 14 having an outlet pipe 14a is installed at the upper end of the rotor 13 to maintain argon gas or flux, and then pushed out to the distribution pipe 13a in the rotor 13 by internal pressure to the crucible. It becomes possible to supply to the molten surface or the molten metal in (11).

In the case of the rotor 13, it is preferable to maintain the fixed state at the upper end of the melting furnace 10, but in some cases, it may be rotated by driving the motor by connecting a normal interlocking means to the rotor (13).

In addition, the mist (mist) made through the usual equipment (not shown) provided separately from the melting furnace 10 may be supplied into the crucible 11 through the distribution pipe (13a) formed in the rotor (13).

With this configuration, after charging silicon processed in the form of powder or pellet into the crucible 11, the melting furnace 10 is heated to a predetermined temperature by the induction heating means 12 in a vacuum atmosphere, and the crucible 11 It can dissolve the silicon inside.

At this time, the flow of the molten metal in the crucible 11 takes place in one direction, and the argon gas or the flux in the chamber 14 passes through the flow pipe 13a in the rotor 13 or the surface of the molten metal in the crucible 11. By supplying the same, impurities contained in the metal silicon can be removed.

In this way, the high vacuum can be maintained while heating the dissolved silicon in the crucible 11 at a high temperature, so that various impurities and boron (B) as well as phosphorus (P) contained in the metal silicon can be more easily removed. will be.

Next, the method of purifying high purity silicon using the apparatus as mentioned above is demonstrated concretely.

First, silicon is molded into powder or pellets, charged into the crucible 11, and heated in an induction heating means 12, and the inside of the melting furnace 10 is vacuumed at about 10 -2 to -10 -4 torr.

Subsequently, while maintaining the temperature in the furnace to 1700 to 1800 ° C. in the vacuum atmosphere for 1 hour, the temperature of the molten metal is lowered to 1400 to 1600 ° C. while argon gas is blown into the furnace to be at atmospheric pressure.

At this time, the induction heating means 12 is a molten metal held in the crucible 11 is heated in a vacuum, the flow of the molten metal in the crucible 11 in one direction by the one-way stirring takes place, such as P, etc. Metals / nonmetals that are easy to evaporate are pushed out of the melt and are easily removed.

Thereafter, 100 kg of the flux held in the chamber 14 is poured into the molten surface or into the molten metal through the distribution pipe 13a in the rotor 13.

Here, the flux may be used by mixing any one or two or more of oxides, such as SiO 2 , CaO, CaF 2 , Al 2 O 3 , MgO, the amount of flux is to be carried out in 20 to 50% of the amount of the melt Most preferred.

In addition, after all the flux is kept in the molten state for a predetermined time to fully react, the mist is pushed into the molten metal through the flow pipe (13a) of the rotor 13 to react with the boron (B) in the molten metal.

Here, after pouring the flux into the molten metal may further include a step of maintaining for one hour while rotating the molten metal by the induction heating means (12).

Thereafter, the rotor 13 is removed from the molten metal and then placed in a coagulation furnace to directionally solidify to obtain final high purity silicon.

The technical problem of the present invention is achieved by the technical configuration as described above, although the present invention has been described by a limited embodiment and drawings, the present invention is not limited thereto but by those skilled in the art to which the present invention pertains. Various modifications and variations are possible, without departing from the spirit and scope of the appended claims.

1 is a conceptual diagram showing a high purity silicon purifier according to the present invention,

2 is a flow chart showing a purification process of high purity silicon.

<Description of the symbols for the main parts of the drawings>

10: melting furnace 11: crucible

12: induction heating means 13: rotor

13a: Distribution Line 14: Chamber

14a: outlet pipe

Claims (6)

With a vacuum furnace, A crucible disposed in the melting furnace for accommodating silicon in powder or pellet form, Induction heating means is installed around the crucible to cause one-way stirring, A rotor disposed to the outside of the melting furnace to inject argon gas or flux into the crucible, And a chamber for pushing the argon gas or the flux into the distribution pipe in the rotor by the internal pressure. 400-600 kg of silicon molded into powder or pellets was charged in a crucible and vacuum-treated in the furnace to 10 -2 to 10 -4 torr while heating by induction heating means, In this vacuum atmosphere, the temperature in the furnace is maintained at 1700 to 1800 ° C. for 50 to 70 minutes, and the temperature of the molten metal is reduced to 1400 to 1600 ° C. while argon gas is blown into the furnace to be at atmospheric pressure. Pouring 80-120 kg of the flux held in the chamber into the molten surface or into the molten metal through a distribution pipe in the rotor, After all the flux enters into the molten state for 50 to 70 minutes to fully react to push the mist into the molten metal through the flow pipe of the rotor to react with the boron in the molten metal, and And removing the rotor from the molten metal and injecting the furnace in an Ar atmosphere to inject it into a coagulation furnace waiting in a separate Ar atmosphere to perform directional solidification. The method of claim 2, The induction heating means is a high-purity silicon purification method characterized in that the molten metal and the additives are mixed by the convection action by one-way stirring while the molten metal held in the crucible is heated in a vacuum. The method according to claim 2 or 3, The flux is a high-purity silicon purification method characterized by using any one or two or more of the oxides, such as SiO 2 , CaO, CaF 2 , Al 2 O 3 , MgO. The method of claim 4, wherein A high purity silicon purifying method, characterized in that the proportion of the flux consists of 15 to 30% of the molten metal. The method of claim 2, And pouring the flux into the molten metal and maintaining the molten metal for 50 to 70 minutes by rotating the molten metal by induction heating means.
KR1020090017866A 2009-03-03 2009-03-03 Apparatus and method for refining of high purity silicon KR20100099396A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101222175B1 (en) * 2011-03-31 2013-01-14 연세대학교 산학협력단 Refining method of impurities from MG-Si by utilizing the density difference between molten Si and reducing slags
CN103274417A (en) * 2013-06-05 2013-09-04 青岛隆盛晶硅科技有限公司 Continuous slag-feeding and slag-discharging device in polycrystalline silicon medium smelting process
KR102328768B1 (en) * 2020-06-25 2021-11-22 주식회사 썸백 High Purity Powder Manufacturing Equipment

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101222175B1 (en) * 2011-03-31 2013-01-14 연세대학교 산학협력단 Refining method of impurities from MG-Si by utilizing the density difference between molten Si and reducing slags
CN103274417A (en) * 2013-06-05 2013-09-04 青岛隆盛晶硅科技有限公司 Continuous slag-feeding and slag-discharging device in polycrystalline silicon medium smelting process
KR102328768B1 (en) * 2020-06-25 2021-11-22 주식회사 썸백 High Purity Powder Manufacturing Equipment

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