WO2023243466A1 - Procédé de production de trichlorosilane purifié - Google Patents

Procédé de production de trichlorosilane purifié Download PDF

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WO2023243466A1
WO2023243466A1 PCT/JP2023/020839 JP2023020839W WO2023243466A1 WO 2023243466 A1 WO2023243466 A1 WO 2023243466A1 JP 2023020839 W JP2023020839 W JP 2023020839W WO 2023243466 A1 WO2023243466 A1 WO 2023243466A1
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trichlorosilane
concentration
isopentane
crude
methyldichlorosilane
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PCT/JP2023/020839
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English (en)
Japanese (ja)
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純也 阪井
昭二 飯山
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株式会社トクヤマ
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Priority to JP2023563332A priority Critical patent/JP7506836B2/ja
Publication of WO2023243466A1 publication Critical patent/WO2023243466A1/fr

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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
    • C01B33/08—Compounds containing halogen
    • C01B33/107—Halogenated silanes

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  • the present invention relates to a method for producing purified trichlorosilane, and more particularly, to a method for obtaining purified trichlorosilane by purifying crude trichlorosilane containing at least isopentane and methyldichlorosilane by distillation.
  • SiHCl 3 high purity trichlorosilane
  • SiHCl 3 polycrystalline silicon
  • Polycrystalline silicon is used, for example, as a raw material for semiconductor or solar power generation wafers.
  • a method for producing trichlorosilane a method is known in which a gas containing hydrogen chloride or silicon tetrachloride and hydrogen is reacted with metallurgical grade silicon.
  • a method of subjecting metallurgical grade silicon to a hydrogen chloride-containing gas at 250°C or higher, generally from 250 to 450°C, or a mixed gas of metallurgical grade silicon, silicon tetrachloride, and hydrogen A method of carrying out a hydrochlorination reaction of and at a temperature of 400°C or higher, generally 400 to 600°C, is known.
  • trichlorosilane is produced as a by-product by, for example, subjecting metallurgical grade silicon to a hydrochlorination reaction with a mixed gas of chlorinated hydrocarbon and hydrogen.
  • Trichlorosilane produced by these methods is free from various side reactions generated by side reactions accompanying the formation of trichlorosilane and by hydrochlorination of carbon impurities contained in the metallurgical grade metal silicon used as the raw material.
  • This is crude trichlorosilane containing raw impurities.
  • By-product impurities typically include trichlorosilane (which is the target of purification such as dichlorosilane (H 2 SiCl 2 : boiling point 8.4°C), tetramethylsilane (Si(CH 3 ) 4 : boiling point 27°C), etc.
  • boiling point means the value under normal pressure (under 1 atmosphere). Therefore, in order to remove by-product impurities contained in such crude trichlorosilane, purification by distillation has conventionally been carried out.
  • Patent Document 1 [0028], Patent Document 2 [0007], and FIG. 1).
  • JP2018-052765A Japanese Patent Application Publication No. 2014-152093
  • distillation purification is a separation method that utilizes the boiling point difference between substances, so if a substance with a small boiling point difference, that is, a by-product impurity contained in the crude trichlorosilane, is classified as the impurity near the boiling point.
  • Patent Document 2 describes crude trichlorosilane with a high content of methyldichlorosilane, which is obtained by removing high-boiling impurities such as low-boiling methylchlorosilanes and silicon tetrachloride (FIG. 1 and [0045]). , a chlorine atom redistribution reaction consisting of a specific step is performed to obtain the above-mentioned fraction with a low methyldichlorosilane content. This fraction with a low methyldichlorosilane content is distilled again to obtain trichlorosilane from which methyldichlorosilane has been considerably removed ([0050]).
  • the present inventors have continued their intensive research in view of the above problems. As a result, the inventors have found that the above-mentioned problems can be solved by subjecting crude trichlorosilane containing at least isopentane and methyldichlorosilane to a specific two-stage distillation, and have completed the present invention.
  • the present invention supplies crude trichlorosilane containing at least isopentane and methyldichlorosilane to a first distillation column, and extracts a low-boiling point fraction whose isopentane concentration is 150 times or more higher than the concentration in the crude trichlorosilane.
  • the trichlorosilane with reduced isopentane concentration is extracted from the bottom of the column by distillation purification in a manner that discharges the trichlorosilane, Next, the obtained trichlorosilane with reduced isopentane concentration is supplied to a second distillation column, and a high boiling point fraction whose methyldichlorosilane concentration is 1.5 times or more higher than the concentration in the crude trichlorosilane is discharged.
  • This is a method for producing purified trichlorosilane, which is characterized in that purified trichlorosilane with a reduced concentration of methyldichlorosilane is distilled out from the top of the column by distillation purification in a specific manner.
  • At least crude trichlorosilane containing isopentane and methyldichlorosilane can be highly reduced in near-boiling impurities that are difficult to separate from these trichlorosilanes, especially isopentane.
  • the polycrystalline silicon produced using the purified trichlorosilane as a raw material has an extremely low amount of carbon impurities, making it possible to produce high-purity silicon single crystals as a raw material for manufacturing semiconductor devices. , is extremely useful industrially.
  • FIG. 1 is a distillation flow diagram showing a typical embodiment of the method for producing purified trichlorosilane according to the present invention.
  • FIG. 2 is a distillation flow diagram showing the method for producing purified trichlorosilane carried out in Comparative Example 1.
  • the crude trichlorosilane used to produce purified trichlorosilane contains at least both isopentane and methyldichlorosilane.
  • the crude trichlorosilane is obtained by reacting the hydrogen chloride or silicon tetrachloride and a hydrogen-containing gas with metallurgical grade silicon.
  • These crude trichlorosilanes are produced by cooling the reaction gas produced by the above reaction to form a condensate, and sending this condensate to a crude trichlorosilane recovery tower to remove impurities with a boiling point higher than silicon tetrachloride, specifically Generally, a metal chloride such as iron chloride is separated and removed.
  • crude trichlorosilane obtained by subjecting metallurgical grade silicon to a hydrochlorination reaction with a mixed gas of chlorinated hydrocarbon and hydrogen can also be used satisfactorily.
  • Such crude trichlorosilane usually contains 10 to 40% mole of trichlorosilane, preferably 20 to 30% mole.
  • crude chlorosilane usually contains 30 to 200 ppb moles of isopentane, more specifically 50 to 100 ppb moles, and 1000 to 20000 ppb moles of methyldichlorosilane, more specifically 6000 to 10000 ppb moles, as impurities. Contains.
  • crude trichlorosilane usually contains 0.1 to 10% mole of dichlorosilane, more specifically 0.2 to 2% mole, as a low boiling point impurity.
  • silicon tetrachloride is usually contained in an amount of 50 to 89.9% by mole, more specifically 70 to 80% by mole.
  • the content of the above-mentioned components means the concentration of the above-mentioned components.
  • low-boiling point impurities such as tetramethylsilane
  • high-boiling point impurities such as trimethylchlorosilane and dimethyldichlorosilane may also be contained.
  • measurements of impurity concentrations of silanes such as methyldichlorosilane, silicon tetrachloride, and dichlorosilane, and isopentane contained in the trichlorosilane refer to values measured using a gas chromatograph.
  • crude trichlorosilane containing at least isopentane and methyldichlorosilane is purified by a specific distillation using a combination of a first distillation column and a second distillation column, which will be described later.
  • Each distillation column used may be either a tray type distillation column or a packed type distillation column.
  • the actual number of stages is not particularly limited, and is, for example, 10 or more and 150 or less, more preferably 20 or more and 100 or less.
  • examples of the filler include a Raschig ring and a Lessing ring.
  • the distillation column can be operated either batchwise or continuously.
  • crude trichlorosilane is first supplied to the first distillation column and purified.
  • isopentane among the impurities near the boiling point is removed by distillation.
  • the greatest feature of the present invention is that isopentane is removed by distillation in this manner prior to the distillation removal of methyldichlorosilane, which is the other component of the near-boiling impurities.
  • the distillative removal of isopentane is carried out in the presence of the methyldichlorosilane.
  • the isopentane concentration is particularly preferably 200 times or more and 300 times or less higher than the isopentane concentration in the crude trichlorosilane.
  • isopentane has a particularly small difference in boiling point from trichlorosilane among the impurities near the boiling point of trichlorosilane, and also exhibits the property of forming an azeotrope with chlorosilanes. , separation by distillation is particularly difficult. Given this property, if distillation is carried out in the coexistence of methyldichlorosilane as described above, it becomes possible to carry out the removal to a higher degree.
  • the isopentane content (isopentane concentration) in crude trichlorosilane is 30 ppb mol or more, more specifically 50 to 100 ppb mol
  • the isopentane content is more preferably 20 ppb mol or less. It is also possible to reduce the amount to 10 to 19 ppb mol.
  • the boiling point difference between isopentane and trichlorosilane is 4.1°C, and the boiling point difference between methyldichlorosilane and trichlorosilane is 10°C. Further, as described above, the isopentane concentration in the crude trichlorosilane is about 30 to 200 ppb mole, and the methyldichlorosilane concentration in the crude trichlorosilane is about 2000 to 20000 ppb mole, as described above.
  • distillation operation it is usually necessary to first perform the distillation operation to remove the components with a large boiling point difference from the target component, and then to remove the components with a small boiling point difference. It will be done.
  • a distillation operation is usually performed to remove components with a high content, and then a distillation operation is performed to remove components with a low content.
  • a distillation operation it is preferable to perform a distillation operation to remove components with a large content first.
  • methyldichlorosilane when distilling crude trichlorosilane to separate isopentane and methyldichlorosilane from the crude trichlorosilane, methyldichlorosilane must be removed first by distillation, both from the viewpoint of boiling point difference and from the viewpoint of content. The isopentane is then removed by distillation.
  • the concentration of isopentane in trichlorosilane is obtained as a value that is reduced to a certain extent when analyzed by the gas chromatography.
  • the effect of removing carbon impurities derived from isopentane is not actually sufficient, and a phenomenon occurs in which the content of carbon impurities is not sufficiently low in polycrystalline silicon produced using this purified trichlorosilane. That is, when the distillation removal operation of methyldichlorosilane is performed first, the isopentane reduction effect obtained by performing the distillation removal operation of isopentane in the coexistence of methyldichlorosilane cannot be obtained.
  • methyldichlorosilane has the effect of inhibiting the formation of an azeotrope between isopentane and the chlorosilanes.
  • isopentane exists alone in trichlorosilane in the coexistence of methyldichlorosilane, so if it is distilled off, a higher degree of purification becomes possible.
  • the isopentane is believed to form an azeotrope with various silanes including the trichlorosilane.
  • the boiling point of the azeotrope of isopentane and trichlorosilane is closer to the boiling point of trichlorosilane than the boiling point of isopentane.
  • the low boiling point fraction whose isopentane concentration is 150 times or more higher than the concentration in the crude trichlorosilane is discharged by heating the crude trichlorosilane stored at the bottom and adjusting the distillation conditions as appropriate.
  • the above-mentioned low boiling point fraction may be discharged from the top or side of the column.
  • the temperature at the top or upper side of the column is set at about 50 to 53°C.
  • the first distillation column it is preferable that a part of the distillate from the top of the column is condensed by cooling and refluxed.
  • the trichlorosilane with reduced isopentane concentration extracted from the bottom of the column is supplied to the second distillation column and purified.
  • the purification in the second distillation column residual methyldichlorosilane among the impurities near the boiling point is removed by distillation.
  • distillation purification is carried out in such a manner that a high boiling point fraction in which the concentration of methyldichlorosilane is 1.5 times or more higher than the concentration in the crude trichlorosilane is discharged, and the concentration of methyldichlorosilane is also reduced from the top of the column.
  • the purified trichlorosilane is distilled off.
  • the concentration of methyldichlorosilane in the high boiling point fraction is 2 to 5 times higher than the concentration in the crude trichlorosilane.
  • the high boiling point fraction whose concentration of methyldichlorosilane is 1.5 times or more higher than the concentration in the crude trichlorosilane is discharged from isopentane, which is supplied from the first distillation column and stored at the bottom.
  • This may be carried out by heating trichlorosilane whose concentration has been reduced, appropriately setting distillation conditions, and extracting the above-mentioned high-boiling point fraction at the bottom or lower side of the column.
  • the temperature at the bottom or lower side of the column is set at about 64 to 67°C.
  • this second distillation column as in the case of the first distillation column, it is preferable that a part of the distillate from the top of the column is condensed and refluxed by cooling, and the reflux ratio at that time is: The larger the number, the better the separation efficiency, but it is set appropriately in consideration of productivity.
  • the content of methyldichlorosilane (methyldichlorosilane concentration) in the isopentane-reduced trichlorosilane is 1000 ppb mol or more, more specifically 2000 to 20000 ppb. Even if it is molar, it is also possible to reduce the content of the methyldichlorosilane to 100 ppb mole or less, more preferably 50 to 90 ppb mole.
  • purified trichlorosilane can be obtained as a clean product with an isopentane content (isopentane concentration) of 20 ppb mol or less and a methyldichlorosilane content (methyldichlorosilane concentration) of 100 ppb mol or less. becomes possible. Moreover, in this purified trichlorosilane, not only the content of detectable isopentane but also the content of difficult-to-detect azeotropes of isopentane and trichlorosilane are extremely low. Therefore, polycrystalline silicon produced using this material has a highly reduced carbon impurity content (carbon concentration).
  • the high boiling point fraction discharged from the second distillation column and having a concentration of methyldichlorosilane that is 1.5 times or more higher than the concentration in the crude trichlorosilane is A third distillation column is supplied to the third distillation column, and a high boiling point fraction in which the methyldichlorosilane concentration is higher (preferably 10 times or more) than the concentration in the crude trichlorosilane is discharged again from the third distillation column. It is also possible to perform distillation purification to obtain purified trichlorosilane with a reduced concentration of methyldichlorosilane distilled from the top of the column.
  • the purified trichlorosilane obtained in this third distillation column also has the same isopentane content (isopentane concentration) and methyldichlorosilane content (methyldichlorosilane concentration) as the purified trichlorosilane discharged from the top of the second distillation column. It is possible to do so.
  • crude trichlorosilane in addition to near-boiling impurities (isopentane and methyldichlorosilane), crude trichlorosilane usually contains dichlorosilane as a low-boiling impurity and silicon tetrachloride as a high-boiling impurity. There is. It is preferable to remove these low-boiling point impurities and high-boiling point impurities to a high degree.
  • the crude trichlorosilane is supplied to the first distillation column, that is, before performing a distillation operation to remove near-boiling point impurities.
  • the crude trichlorosilane is supplied to the pre-first distillation column, and purified by distillation in a manner that discharges a high boiling point fraction in which the silicon tetrachloride concentration is 1.1 times or more higher than the concentration in the crude trichlorosilane.
  • Crude trichlorosilane with reduced silicon tetrachloride concentration is distilled from the top, Next, the obtained crude trichlorosilane with a reduced silicon tetrachloride concentration is supplied to a pre-second distillation column, and a low boiling point fraction whose dichlorosilane concentration is 100 times or more higher than the concentration in the crude trichlorosilane is discharged. Crude trichlorosilane with reduced dichlorosilane concentration is extracted from the bottom of the column and supplied to the first distillation column. This will be implemented by In this specification, the crude trichlorosilane with reduced dichlorosilane concentration extracted from the bottom of the pre-second distillation column is also referred to as pre-purified trichlorosilane.
  • silicon tetrachloride which is a high-boiling point impurity and has a high content (high concentration) in the crude trichlorosilane
  • distillation purification is performed in such a manner that a high boiling point fraction in which the silicon tetrachloride concentration is 1.1 times or more higher than the concentration in the crude trichlorosilane is discharged, and the silicon tetrachloride concentration is reduced from the top of the column. Distill the trichlorosilane.
  • the silicon tetrachloride concentration in the high boiling point fraction is 1.2 to 2 times higher than the concentration in the crude trichlorosilane.
  • the high boiling point fraction whose silicon tetrachloride concentration is 1.1 times or more higher than the concentration in the crude trichlorosilane is discharged by heating the crude trichlorosilane stored at the bottom,
  • the distillation may be carried out by appropriately setting distillation conditions and extracting the above-mentioned high boiling point fraction from the bottom or lower side of the column.
  • the temperature at the bottom or lower side of the column is set at about 90 to 93°C.
  • the high boiling point fraction may contain solid content such as unreacted silicon fine powder.
  • this pre-first distillation column as in the case of the first distillation column, it is preferable that a part of the distillate from the top of the column is condensed and refluxed by cooling, and the reflux ratio at that time is , the larger the separation efficiency, the better the separation efficiency, but it is set appropriately in consideration of productivity.
  • the content of silicon tetrachloride (silicon tetrachloride concentration) in the crude trichlorosilane was 50% mole or more, more specifically 50 to 89.9% mole. However, it is also possible to reduce the content (concentration) to 0.1% mole or less, more preferably 10 ppm mole or less (TCD detection limit value).
  • the subsequent purification in the pre-second distillation column involves distillation removal of dichlorosilane, which is a low-boiling point impurity and has a relatively large content (relatively high concentration) in the crude trichlorosilane.
  • distillation purification is performed in such a manner that a low boiling point fraction with a dichlorosilane concentration 100 times or more higher than the concentration in the crude trichlorosilane is discharged, and trichlorosilane with a reduced dichlorosilane concentration is extracted from the bottom of the column. Pull it out.
  • the dichlorosilane concentration in the low boiling point fraction is 100 to 200 times higher than the concentration in the crude trichlorosilane.
  • the low boiling point fraction whose dichlorosilane concentration is 100 times or more higher than the concentration in the crude trichlorosilane is discharged by heating the silicon tetrachloride-reduced trichlorosilane stored at the bottom.
  • the distillation may be carried out by appropriately setting distillation conditions and discharging the above-mentioned low boiling point fraction from the top or upper side of the column.
  • the temperature at the top or upper side of the column is set at about 40 to 43°C.
  • this pre-second distillation column as in the case of the first distillation column, it is preferable that a part of the distillate from the top of the column is condensed and refluxed by cooling, and the reflux ratio at that time is , the larger the separation efficiency, the better the separation efficiency, but it is set appropriately in consideration of productivity.
  • the content of dichlorosilane (dichlorosilane concentration) in trichlorosilane with reduced silicon tetrachloride concentration is 0.1% mole or more, more specifically 0.2%. Even if it is ⁇ 2% mole, it is possible to reduce its content (concentration) to less than 0.1% mole, more preferably to 10 ppm mole or less (TCD detection limit value).
  • trichlorosilane with a reduced dichlorosilane concentration extracted from the bottom of the pre-second distillation column that is, pre-purified trichlorosilane is obtained.
  • the contents (concentrations) of silicon tetrachloride and dichlorosilane are both at a clean level of 10 ppm mol (TCD detection limit value) or less, and this is supplied to the first distillation column. becomes possible. Therefore, in pre-purified trichlorosilane, the trichlorosilane content (trichlorosilane concentration) is preferably 99% mole or more, more preferably 99.5% mole or more, and 99.9% mole or more. It is even more preferable.
  • the concentration of these near-boiling impurities in crude trichlorosilane containing silicon tetrachloride and dichlorosilane (crude trichlorosilane before pre-purification) and the concentration of these near-boiling impurities in pre-purified trichlorosilane are substantially the same. It is normal that there is. However, if these have changed significantly, the reference concentration of isopentane and methyldichlorosilane before discharge is determined in the removal of these near-boiling impurities, which is performed in combination with the subsequent first distillation column and second distillation column. may be determined based on the concentration in the pre-purified trichlorosilane immediately before the removal treatment.
  • the purified trichlorosilane obtained by the method of the present invention is further purified by adsorption and removal, and mixed with trichlorosilane recovered from the exhaust gas after polycrystalline silicon is precipitated using the purified trichlorosilane. Processing may be performed as appropriate.
  • FIG. 1 is a distillation flow diagram of an embodiment including pre-purification.
  • a liquid flow of crude trichlorosilane produced by reacting a gas containing hydrogen chloride or silicon tetrachloride and hydrogen with metallurgical grade silicon flows through a crude trichlorosilane flow pipe 1. are doing.
  • this crude trichlorosilane contains high boiling point impurities such as silicon tetrachloride and low boiling point impurities such as dichlorosilane.
  • This crude trichlorosilane is first subjected to pre-purification to remove silicon tetrachloride, which is a high boiling point impurity, and dichlorosilane, which is a low boiling point impurity. That is, the crude trichlorosilane flow pipe 1 is connected to the side of the pre-first distillation column 2, and the crude trichlorosilane liquid stream is supplied to the pre-first distillation column 2. In the pre-first distillation column 2, the crude trichlorosilane liquid stored at the bottom is heated, and distillation and purification thereof is carried out under the conditions described above.
  • the bottom liquid corresponding to the high boiling point fraction whose silicon tetrachloride concentration is 1.1 times or more higher than the concentration in the crude trichlorosilane is transferred from the bottom of the column to the silicon tetrachloride concentration column bottom liquid extraction pipe 3.
  • a gas phase of trichlorosilane with a reduced silicon tetrachloride concentration is distilled from the top of the column to a silicon tetrachloride-reduced trichlorosilane distillation pipe 4.
  • the gas phase of the silicon tetrachloride-reduced trichlorosilane distilled into the silicon-tetrachloride-reduced trichlorosilane distillation pipe 4 is liquefied by the condenser 5, and a part of the liquid stream is transferred to the silicon-tetrachloride-reduced trichlorosilane reflux pipe 6. From there, it is refluxed to the pre-first distillation column 2.
  • the other silicon tetrachloride-reduced trichlorosilane supply pipe 7 branched from the silicon tetrachloride-reduced trichlorosilane reflux pipe 6 is connected to the side of the pre-second distillation column 8 .
  • the remaining liquid stream of silicon tetrachloride-reduced trichlorosilane refluxed to the pre-first distillation column 2 is supplied to the pre-first distillation column 2.
  • the silicon tetrachloride-reduced trichlorosilane liquid stored at the bottom is heated, and its distillation purification is carried out under the conditions described above.
  • a gas phase corresponding to a low boiling point fraction in which the dichlorosilane concentration is 100 times or more higher than the concentration in the crude trichlorosilane is distilled from the top of the column to the dichlorosilane concentrate distillation tube 10, and on the other hand, A liquid stream of pre-purified trichlorosilane with a reduced dichlorosilane concentration is extracted from the bottom to a pre-purified trichlorosilane extraction pipe 9 .
  • the gas phase of the dichlorosilane concentrate distilled into the dichlorosilane concentrate distillation pipe 10 is liquefied by the condenser 11, and a part of the liquid stream is transferred from the dichlorosilane concentrate reflux pipe 12 to the pre-second distillation It is refluxed to column 8.
  • the remaining dichlorosilane concentrate is sent out of the system from the other dichlorosilane concentrate distribution pipe 13 branched from the dichlorosilane concentrate reflux pipe 12.
  • isopentane and methyldichlorosilane are removed from the pre-purified trichlorosilane flowing through the pre-purified trichlorosilane extraction pipe 9 from which silicon tetrachloride and dichlorosilane have been removed. . That is, the pre-purified trichlorosilane extraction pipe 9 is connected to the side of the first distillation column 14, and the liquid stream of the pre-purified trichlorosilane is supplied to the first distillation column 14. In the first distillation column 14, the pre-purified trichlorosilane liquid stored at the bottom is heated and distilled and purified under the conditions described above.
  • the gas phase of the isopentane concentrate distilled into the isopentane concentrate distillation pipe 16 is liquefied by the condenser 17, and a part of the liquid stream is refluxed from the isopentane concentrate reflux pipe 18 to the first distillation column 14. be done.
  • the remaining isopentane concentrate is sent out of the system from the other isopentane concentrate distribution pipe 19 branched from the isopentane concentrate reflux pipe 18.
  • the isopentane-reduced trichlorosilane extraction pipe 15 is connected to the side of the second distillation column 20, and the second distillation column 20 is supplied with a liquid stream of the isopentane-reduced trichlorosilane.
  • the isopentane-reduced trichlorosilane liquid stored at the bottom is heated and distilled and purified under the conditions described above.
  • the bottom liquid corresponding to the high boiling point fraction whose methyldichlorosilane concentration is 1.5 times or more higher than the concentration in the crude trichlorosilane is transferred from the bottom of the column to the methyldichlorosilane concentration column bottom liquid extraction pipe 21.
  • a gaseous phase of trichlorosilane with a reduced concentration of methyldichlorosilane is distilled from the top of the column to a purified trichlorosilane distillation tube 22.
  • the gas phase of the purified trichlorosilane distilled into the purified trichlorosilane distillation tube 22 is liquefied by the condenser 23, and a part of the liquid stream is refluxed from the purified trichlorosilane reflux tube 24 to the second distillation column 20. be done.
  • purified trichlorosilane subjected to the manufacturing method of the present invention is taken out as a residual liquid from the other purified trichlorosilane flow pipe 25 branched from the purified trichlorosilane reflux pipe 24.
  • the purified trichlorosilane thus obtained may be usefully used as a raw material for producing polycrystalline silicon.
  • Iron chloride (FeCl 3 ), aluminum chloride (AlCl 3 ), organic chlorosilane, and various other organic substances are contained as trace components in the generated gas.
  • the composition of the raw materials used was that the metallurgical grade silicon had a silicon concentration of 99% by mass, an iron concentration of 0.7% by mass, an aluminum concentration of 0.3% by mass, and a carbon concentration of 300ppmwt, silicon tetrachloride and hydrogen. The purity was 99% by mass or more.
  • the reaction product gas containing trichlorosilane was cooled to a temperature range of 0 to 20°C to obtain a cooled condensate.
  • This coolant was sent to a crude trichlorosilane recovery tower to separate metal chlorides such as iron chloride, which have a boiling point higher than silicon tetrachloride, to obtain a crude trichlorosilane liquid.
  • the composition of the obtained crude trichlorosilane liquid is as follows: trichlorosilane concentration is 27.2% mole, silicon tetrachloride concentration is 72.3% mole, dichlorosilane concentration is 0.5% mole, methyldichlorosilane concentration is 15000 ppb mole, The isopentane concentration was 85 ppb mole, and the iron chloride concentration and aluminum chloride concentration were each less than 1 ppb-wt.
  • Example 1 The crude trichlorosilane liquid was subjected to the distillation flow shown in FIG. 1 and treated.
  • each distillation column In the distillation flow shown in FIG. 1, the pre-first distillation column 2 and the pre-second distillation column 8 each had a column diameter of 150 mm and a theoretical plate number of 30.
  • the pre-first distillation column 2 was operated under the conditions that the pressure at the bottom of the column was 200 kPa (gauge pressure) and the temperature at the bottom of the column was 91 to 92°C.
  • the pre-second distillation column 8 was operated under the conditions that the pressure at the top of the column was 100 kPa (gauge pressure) and the temperature at the top of the column was 41 to 42°C.
  • the first distillation column 14 was operated under the conditions that the pressure at the top of the column was 100 kPa (gauge pressure) and the temperature at the top of the column was 51 to 52°C.
  • the second distillation column 20 was operated under the conditions that the pressure at the bottom of the column was 200 kPa (gauge pressure) and the temperature at the bottom of the column was 65 to 66°C.
  • Pre-first distillation column 2 When we sampled the bottom liquid flowing through the silicon tetrachloride concentration column bottom liquid extraction pipe 3 and analyzed its composition, we found that the silicon tetrachloride concentration was 99.9% molar, and the trichlorosilane concentration was below the detection limit of 10 ppm molar. there were.
  • the concentration of silicon tetrachloride in the column bottom liquid is 1.38 times higher than the concentration in the crude trichlorosilane.
  • the impurity methyldichlorosilane was removed to a high degree from the trichlorosilane distilled from the filtrate and flowing through the purified trichlorosilane distillation tube 22.
  • the composition of the purified trichlorosilane sampled from the purified trichlorosilane flow pipe 25 we found that the trichlorosilane concentration was 99.9% molar, the isopentane concentration was 17 ppb molar, and the methyldichlorosilane concentration was 72 ppb. It was of high molar purity.
  • Comparative example 1 Purified trichlorosilane was produced in the same manner as in Example 1, except that the distillation flow of the crude chlorosilane liquid was changed from that shown in FIG. 1 to that shown in FIG. 2.
  • the distillation flow of FIG. 2 in the one shown in FIG. 1, crude trichlorosilane (pre-purified trichlorosilane) is distilled, but isopentane concentrate is distilled from the top of the column in the first distillation column 14, and isopentane reduction is distilled from the bottom of the column.
  • the process differs in that reduced trichlorosilane is supplied to the first distillation column, and in the first distillation column 14, isopentane concentrate is distilled from the top of the column, and purified trichlorosilane is obtained from the bottom of the column.
  • isopentane concentrate is distilled from the top of the column
  • purified trichlorosilane is obtained from the bottom of the column.
  • the concentration of methyldichlorosilane in the bottom liquid is 2.2 times higher than the concentration in crude trichlorosilane (pre-purified trichlorosilane), and from this, even if methyldichlorosilane is removed first, It was confirmed that methyldichlorosilane was highly removed from the trichlorosilane distilled from the top of the second distillation column 20 and flowing through the methyldichlorosilane-reduced trichlorosilane distillation tube 22.
  • Example 1 the distillation of isopentane in the first distillation column 14 is carried out in the presence of methyldichlorosilane, and in this state, the isopentane is also removed as an azeotrope, whereas in Comparative Example 1, the isopentane is removed as an azeotrope.
  • the distillation of isopentane in the first distillation column 14 is caused by the fact that most of the methyldichlorosilane is removed in the second distillation column 20, and therefore the azeotrope of isopentane is insufficiently removed.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)

Abstract

[Problème] Réduire considérablement, dans le trichlorosilane qui sert de matière première pour la production de silicium polycristallin ou similaire, la concentration de diméthyldichlorosilane et d'isopentane, qui sont des impuretés ayant des points d'ébullition similaires audit trichlorosilane. [Solution] L'invention porte sur un procédé de production de trichlorosilane purifié, le procédé étant caractérisé par au moins : la fourniture de trichlorosilane brut contenant de l'isopentane et du méthyldichlorosilane à une première colonne de distillation ; la réalisation d'une purification par distillation de manière à évacuer une fraction à faible plage de points d'ébullition dans laquelle la concentration d'isopentane est au moins 150 fois supérieure à la concentration d'isopentane dans le trichlorosilane brut ; l'élimination du trichlorosilane ayant une concentration d'isopentane réduite dans le fond de la colonne, puis la fourniture du trichlorosilane ayant une concentration d'isopentane réduite obtenu à une seconde colonne de distillation ; la réalisation d'une purification par distillation de manière à évacuer une fraction de plage de points d'ébullition élevé dans laquelle la concentration de méthyldichlorosilane est au moins 1,5 fois supérieure à la concentration de méthyldichlorosilane dans le trichlorosilane brut ; et la distillation du trichlorosilane purifié ayant une concentration de méthyldichlorosilane réduite dans la partie supérieure de la colonne.
PCT/JP2023/020839 2022-06-13 2023-06-05 Procédé de production de trichlorosilane purifié WO2023243466A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06211882A (ja) * 1993-01-11 1994-08-02 Wacker Chemie Gmbh 共沸混合物テトラクロルシラン−トリメチルクロルシランを蒸留により分離する方法
JP2004149351A (ja) * 2002-09-04 2004-05-27 Sumitomo Titanium Corp クロロシラン及びその精製方法
JP2009062212A (ja) * 2007-09-05 2009-03-26 Shin Etsu Chem Co Ltd トリクロロシランの製造方法および多結晶シリコンの製造方法
WO2020137853A1 (fr) * 2018-12-27 2020-07-02 株式会社トクヤマ Procédé de fabrication de chlorosilane

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06211882A (ja) * 1993-01-11 1994-08-02 Wacker Chemie Gmbh 共沸混合物テトラクロルシラン−トリメチルクロルシランを蒸留により分離する方法
JP2004149351A (ja) * 2002-09-04 2004-05-27 Sumitomo Titanium Corp クロロシラン及びその精製方法
JP2009062212A (ja) * 2007-09-05 2009-03-26 Shin Etsu Chem Co Ltd トリクロロシランの製造方法および多結晶シリコンの製造方法
WO2020137853A1 (fr) * 2018-12-27 2020-07-02 株式会社トクヤマ Procédé de fabrication de chlorosilane

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