CN117985724A - Purifying device and purifying method for hexachlorodisilane - Google Patents
Purifying device and purifying method for hexachlorodisilane Download PDFInfo
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- CN117985724A CN117985724A CN202410126437.3A CN202410126437A CN117985724A CN 117985724 A CN117985724 A CN 117985724A CN 202410126437 A CN202410126437 A CN 202410126437A CN 117985724 A CN117985724 A CN 117985724A
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- hexachlorodisilane
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- circulating
- electrode
- impurity removing
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- LXEXBJXDGVGRAR-UHFFFAOYSA-N trichloro(trichlorosilyl)silane Chemical compound Cl[Si](Cl)(Cl)[Si](Cl)(Cl)Cl LXEXBJXDGVGRAR-UHFFFAOYSA-N 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000012535 impurity Substances 0.000 claims abstract description 154
- 239000007788 liquid Substances 0.000 claims abstract description 52
- 229910052751 metal Inorganic materials 0.000 claims abstract description 42
- 239000002184 metal Substances 0.000 claims abstract description 42
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 19
- 239000002994 raw material Substances 0.000 claims abstract description 15
- 238000007599 discharging Methods 0.000 claims abstract description 14
- 238000006479 redox reaction Methods 0.000 claims abstract description 11
- 230000001681 protective effect Effects 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 22
- 238000000746 purification Methods 0.000 claims description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 18
- 229910002804 graphite Inorganic materials 0.000 claims description 18
- 239000010439 graphite Substances 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 14
- 239000011261 inert gas Substances 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 239000000460 chlorine Substances 0.000 claims description 10
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims description 10
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 10
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052801 chlorine Inorganic materials 0.000 claims description 2
- 238000006722 reduction reaction Methods 0.000 abstract description 9
- 150000001768 cations Chemical class 0.000 abstract description 7
- 229910021645 metal ion Inorganic materials 0.000 abstract description 7
- 239000003960 organic solvent Substances 0.000 abstract 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- 230000000694 effects Effects 0.000 description 14
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000000151 deposition Methods 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 229910001385 heavy metal Inorganic materials 0.000 description 3
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 3
- 229920005591 polysilicon Polymers 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- -1 cyclic ether compound Chemical class 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000000600 sorbitol Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 235000012431 wafers Nutrition 0.000 description 1
Classifications
-
- 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
- C01B33/10778—Purification
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/06—Operating or servicing
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention discloses a purifying device and a purifying method of hexachlorodisilane, comprising an electrode group, a plurality of groups of water-soluble organic solvents, a plurality of groups of water-soluble organic solvents and a plurality of groups of water-soluble organic solvents, wherein the electrode group is used for removing metal impurities through oxidation-reduction reaction on a positive electrode and a negative electrode of the electrode group; the electrolytic impurity removing tank is of a closed structure, the inside of the electrolytic impurity removing tank is used for installing the electrode groups, and a plurality of electrode groups are sequentially arranged in the electrolytic impurity removing tank along the flow direction of raw materials; the side wall of the electrolytic impurity removing groove is provided with a liquid adding port, a liquid discharging port, a protective gas port and an air outlet; the circulating pipeline is respectively communicated with a circulating liquid inlet and a circulating liquid outlet of the electrolytic impurity removal tank; and the circulating pump is arranged on the circulating pipeline and is used for providing driving force for the circulating flow of hexachlorodisilane raw material. The scheme adopts an electrolysis mode, metal cations are deposited by reduction reaction in the cathode, and the metal ions are removed comprehensively.
Description
Technical Field
The invention belongs to the technical field of hexachlorodisilane purification, and particularly relates to a hexachlorodisilane purification device and a hexachlorodisilane purification method.
Background
Compared with the traditional dichlorosilane and silane vapor deposition method for preparing the silicon film, the high-purity Hexachlorodisilane (HCDS) has the advantages of low deposition temperature, low deposition pressure and high deposition efficiency in the vapor deposition method of hexachlorodisilane, and the obtained silicon film has better insulativity, corrosion resistance and compatibility. The preparation method is widely applied to the preparation of a thin film intermediate dielectric layer, a polysilicon interconnection line surrounding layer and a grid transistor spacing layer, and is a key silicon-based semiconductor raw material for manufacturing high-end chips, wafers, memories and logic chips.
At present, hexachlorodisilane raw materials are mostly sourced from tail gas condensate of a polysilicon system reduction furnace, the components are complex, the content of various metal impurities is high, particularly Al, fe, ti, V, cr and the like, the content is different from thousands to hundreds ppb, uniform and efficient removal is difficult to perform, and the existing process has low product yield and high production cost.
In the related art, the main disadvantages of hexachlorodisilane purification are: firstly, a process route of a rectification method needs a plurality of groups of rectification towers, the flow is complex, the one-time investment is large, the metal impurity removal effect is general, and the material loss is large; secondly, the process route of the extraction method is long in standing time, organic matters are mutually dissolved, and metal impurities are difficult to effectively separate by extraction; thirdly, the process route of the distillation method after adding the cyclic ether compound only has the effect of removing titanium, and other metal impurities are not obviously reduced; fourthly, the hexachlorodisilane raw material has high content of metal impurities, and a process route for removing the metal impurities by adopting sorbitol, chelating resin needs to consume a large amount of adsorbents, and has high replacement frequency and high cost.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
Therefore, an embodiment of the invention provides a purifying device of hexachlorodisilane, the invention sets the electrolytic impurity removing tank into a closed structure by improving equipment of the electrolytic impurity removing tank, meanwhile, a protection air source is arranged on the electrolytic impurity removing tank for carrying out inert gas replacement and protection on the inside of the electrolytic impurity removing tank, meanwhile, a graphite rod electrode is arranged in the electrolytic impurity removing tank, other impurities are not introduced, and secondly, a circulating pipeline is arranged at the inlet and outlet ends of the electrode impurity removing tank, and a circulating pump is arranged on the circulating pipeline, so that circulating power is provided for materials in the electrode impurity removing tank, and the electrolytic efficiency can be further improved.
The embodiment of the other aspect of the invention provides a purification method of hexachlorodisilane, which has good effect of removing metal impurities in hexachlorodisilane and strong pertinency; the hexachlorodisilane to-be-treated liquid is introduced into the electrolytic impurity removing tank, and metal cations are deposited by reduction reaction at the negative electrode in an electrolytic mode, so that the hexachlorodisilane to-be-treated liquid has removing effects on all metal ions, has better removing effects on high-valence and heavy metal impurities with high electron obtaining capability, and is more comprehensive in metal ion removal. Besides a small amount of exhaust gas is discharged, the material loss is small, and the yield of hexachlorodisilane is high.
An embodiment according to a first aspect of the present invention provides a purification apparatus for hexachlorodisilane, comprising an electrode group provided with a plurality of groups for removing metal impurities by oxidation-reduction reaction on a positive electrode and a negative electrode thereof; the electrolytic impurity removing tank is of a closed structure, the inside of the electrolytic impurity removing tank is used for installing the electrode groups, and a plurality of electrode groups are sequentially arranged in the electrolytic impurity removing tank along the flow direction of raw materials; the side wall of the electrolytic impurity removing tank is provided with a liquid adding port, a liquid discharging port, a protective gas interface and an air outlet, wherein the liquid adding port is used for introducing hexachlorodisilane raw materials to be treated into the electrolytic impurity removing tank, and the protective gas interface is used for introducing inert gas into the electrolytic impurity removing tank and replacing and protecting the interior of the electrolytic impurity removing tank; the exhaust port is used for exhausting gas generated by electrolysis to the outside of the electrolytic impurity removal tank through the exhaust port; the liquid outlet is used for discharging and collecting products through the liquid outlet after the electrolysis is completed; the circulating pipeline is respectively communicated with a circulating liquid inlet and a circulating liquid outlet of the electrolytic impurity removal tank, the circulating liquid inlet and the circulating liquid outlet are respectively arranged on the side walls of the feeding side and the discharging side of the electrode group and are used for realizing that after materials in the electrolytic impurity removal tank are discharged from the circulating liquid outlet side, the materials return to the other end circulating liquid inlet side of the electrolytic impurity removal tank through the circulating pipeline and the circulating liquid inlet; and the circulating pump is arranged on the circulating pipeline and is used for providing driving force for the circulating flow of hexachlorodisilane raw material.
According to the purification device, the electrolytic impurity removal tank is simple in structure, low in power consumption, low in electrode replacement cost, long in service life and convenient to examine and maintain. Through setting up circulation liquid inlet and circulation liquid export respectively in the import and export side of electrolytic edulcoration groove to through circulation pipeline and circulating pump, drive the material circulation flow in the electrolytic edulcoration groove, the material is continuous to circulate and is carried out the electrolytic edulcoration, and multiple reaction increases the reaction probability, and the edulcoration is effectual.
Preferably, the exhaust port is communicated with an alkaline washing unit and is used for carrying out alkaline washing treatment on hydrogen chloride and chlorine generated by electrolysis.
The generated small amount of gas is treated by the alkaline washing unit, so that on one hand, the over-pressure in the impurity removing tank can be avoided, and meanwhile, the generated harmful gas can be prevented from polluting the environment by discharging the generated harmful gas after alkaline washing.
Preferably, the electrode group is provided with 2-6 groups.
As a preferable scheme, the inner wall of the electrolytic impurity removal tank is provided with a PTFE or PFA lining layer, so that the introduction of impurities can be avoided.
Preferably, the electrode group comprises a positive electrode and a negative electrode, and the positive electrode and the negative electrode both adopt graphite rods. The electrode material is graphite, has good conductivity and stable property, and does not introduce other impurities.
Preferably, the number of graphite rods in each electrode group is 2-8 pairs.
An embodiment according to a second aspect of the present invention provides a method for purifying hexachlorodisilane, comprising the following steps:
Step one, before feeding, the electrolytic impurity removing tank is replaced by introducing high-purity inert gas through a protecting gas port, so that air and moisture are prevented from entering, the pressure in the electrolytic impurity removing tank is kept between 10 and 100kPa, and the internal temperature is controlled between 10 and 50 ℃;
Step two, hexachlorodisilane to be treated with high metal impurity content is added through a liquid adding port of an electrolytic impurity removing tank; the volume of the added hexachlorodisilane is 85% -95% of the volume of the electrolytic impurity removal tank;
Step three, the electrode group starts to be electrified with direct current, metal impurities are removed through oxidation-reduction reaction on the positive electrode and the negative electrode of the electrode group, and the direct current voltage of the graphite rod of the electrode group is controlled to be 5-48V;
step four, circulating hexachlorodisilane by starting a circulating pump, wherein the circulating time is 4-8 hours;
Step five, generating a small amount of HCl and Cl 2 through oxidation at the positive electrode of the electrode group, discharging from an exhaust port after the pressure of the electrolytic impurity removing tank is higher than a set pressure, and absorbing by an alkaline washing unit;
and step six, collecting and detecting products through a liquid outlet of the electrode impurity removal tank after the cycle time of the electrolytic impurity removal tank reaches 4-8 hours.
According to the purification method provided by the invention, the method for comprehensively and efficiently removing the metal impurities in hexachlorodisilane is provided. By matching with the specific purification device, the process index is strictly controlled, the metal cations are deposited by reduction reaction at the negative electrode in an electrolysis mode, the removal effect on all metal ions is achieved, the removal effect on high-valence and heavy metal impurities with high electron obtaining capability is better, and the removal of the metal ions is more comprehensive. In the purification process, besides a small amount of exhaust gas, the material loss is less, and the yield of hexachlorodisilane is high.
In some embodiments, in the first step, the pressure in the electrolytic impurity removing tank is 10kPa to 100kPa, the internal temperature is controlled to be 10 ℃ to 50 ℃, preferably, the pressure in the electrolytic impurity removing tank is 30kPa to 60kPa, and the internal temperature is controlled to be 20 ℃ to 40 ℃.
In some embodiments, in the third step, the graphite rod dc voltage of the electrode group is controlled to be 5V to 48V, preferably 10V to 24V.
In some embodiments, in step four, the circulation pump circulates hexachlorodisilane material volume per hour: the volume of the electrolytic impurity removing tank is 0.5:1-2:1.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of a purification apparatus of the present invention;
FIG. 2 is a schematic diagram of the material circulation principle of the purification device of the present invention;
The marks in the figure: 1. electrode group, 2, electrolytic impurity removal groove, 3, the liquid filling port, 4, the leakage fluid dram, 5, the shielding gas interface, 6, the gas vent, 7, circulation pipeline, 8, the circulating pump, 9, alkaline washing unit.
Detailed Description
The invention is described in detail below by way of exemplary embodiments. It is to be understood that elements, structures and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
It should be noted that: unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used in the specification and claims of this application, the terms "a," "an," and "the" and similar referents are not to be construed to limit the scope of at least one. The word "comprising" or "comprises", and the like, indicates that elements or items listed thereafter or equivalents thereof may be substituted for elements or items thereof in addition to those listed thereafter or equivalents thereof without departing from the scope of the word "comprising" or "comprising".
As shown in the drawing, in an exemplary embodiment of the present invention, there is provided a hexachlorodisilane purification apparatus comprising an electrode group 1, an electrolytic impurity removing tank 2, a circulation pipe 7, a circulation pump 8, and an alkaline washing unit 9, wherein the electrode group 1 is provided with a plurality of groups, each group of the electrode groups 1 comprising a positive electrode and a negative electrode for removing metal impurities by performing oxidation-reduction reactions on the positive electrode and the negative electrode thereof; the electrolytic impurity removing tank 2 is of a closed structure, and a plurality of electrode groups 1 are sequentially arranged in the electrolytic impurity removing tank 2 along the flow direction of raw materials; the side wall of the circulation inlet side and the side wall of the circulation outlet side of the electrolytic impurity removal tank 2 are connected with two ends of a circulation pipeline 7, and after the materials in the electrolytic impurity removal tank 2 are discharged from the side of the circulation liquid outlet, the materials return to the side of the circulation liquid inlet at the other end of the electrolytic impurity removal tank 2 through the circulation pipeline 7 and the circulation liquid inlet; the circulating pipe 7 is provided with a circulating pump 8, and the circulating pump 8 adopts a diaphragm pump or a gear pump. Thereby providing a driving force for the circulating flow of hexachlorodisilane starting material. According to the scheme, the circulating pipeline 7 is arranged on the side wall of the circulating inlet and the side wall of the circulating outlet of the electrode group 1 of the electrolytic impurity removal tank 2, so that the probability of reduction and deposition of metal impurities on the negative electrode can be effectively improved by starting the circulating pump 8 for circulation, and the impurity removal efficiency is improved.
In one embodiment of the invention, the volume of the electrolytic impurity removing tank 2 is 50L-200L, the material is 304L or 316L stainless steel, preferably 316L, and PTFE or PFA lining layers are arranged in the electrolytic impurity removing tank 2, so that the electrolytic impurity removing tank has good stability and corrosion resistance, the introduction of external impurities can be avoided, and the working pressure in the electrolytic impurity removing tank 2 is 10 kPa-100 kPa, preferably 30 kPa-60 kPa; the control temperature is used at 10℃to 50℃and preferably at 20℃to 40 ℃.
In the invention, the side wall of the electrolytic impurity removal tank 2 is provided with a liquid adding port 3 and a liquid discharging port 4, wherein the purpose of arranging the liquid adding port 3 is as follows: the device is used for introducing hexachlorodisilane raw materials to be treated into the electrolytic impurity removal tank 2, and the liquid outlet 4 is used for discharging and collecting detection products through the liquid outlet 4 after the electrolysis is completed, and can be used for replacing and pressure relief.
In one embodiment of the invention, the electrolytic impurity removing tank 2 is further provided with a shielding gas port 5 and an exhaust port 6, and the purpose of the shielding gas port 5 is that: the device is used for introducing inert gas into the electrolytic impurity removal tank 2 and replacing and protecting the interior of the electrolytic impurity removal tank 2; the exhaust port 6 is used for exhausting the gas generated by electrolysis to the outside of the electrolytic impurity removal tank 2 through the top exhaust port 6. In the electrolysis process, the anode is oxidized to generate a small amount of HCl and Cl 2, and after the internal pressure of the electrolytic impurity removal tank 2 is higher than the set pressure, the water is discharged from the top exhaust port 6 and is absorbed by the alkaline washing unit 9.
In the invention, the electrode group 1 in the single electrolytic impurity removing groove 2 is provided with 2 groups to 6 groups, preferably 4 groups to 6 groups; each electrode group 1 comprises a positive electrode and a negative electrode, wherein the materials of the positive electrode and the negative electrode are graphite, and the number of graphite rods of each electrode group is 2-8 pairs, preferably 4-8 pairs. The electrode material is made of graphite, so that the electrode material has good conductivity and stable property, and other impurities are not introduced.
Another exemplary embodiment of the present invention also provides a method for purifying hexachlorodisilane, comprising the following steps:
Step one, before feeding, the electrolytic impurity removing tank 2 is replaced by introducing high-purity inert gas through a protective gas interface 5, static replacement is that high-purity nitrogen is filled from the top protective gas interface 5, the pressure is 0.2 MPaG-0.3 MPaG, the electrolytic impurity removing tank is kept stand for 10 min-30 min, the pressure is relieved from a liquid outlet 4 at the bottom, the pressure is relieved to 10 kPaG-50 kPaG, the reciprocating is carried out for 3-5 times, and when the gas dew point in the electrolytic impurity removing tank 2 is less than or equal to-50 ℃, and the micro oxygen is less than or equal to 10ppm, the replacement is qualified; the hexachlorodisilane is prevented from being polluted by water and oxygen due to incomplete replacement, and the working pressure in the electrolytic impurity removing tank 2 is kept between 10kPa and 100kPa, preferably between 30kPa and 60kPa in the whole electrolytic impurity removing process; the internal temperature is controlled to be 10-50 ℃, preferably 20-40 ℃;
According to the scheme, the high-purity inert gas can be selected from nitrogen, the nitrogen is preferably high-purity nitrogen, the purity of the nitrogen is more than or equal to 5N, the moisture is less than or equal to 10ppb, and the oxygen is less than or equal to 10ppb. Through nitrogen replacement and finally through nitrogen to carry out inert gas's protection, can avoid external air and moisture's entering, avoid the pollution to the inside of electrolytic edulcoration groove 2.
Step two, hexachlorodisilane to be treated with high metal impurity content is added through a liquid adding port of the electrolytic impurity removing tank 2; the volume of the added hexachlorodisilane is 85% -95% of the volume of the electrolytic impurity removal tank 2;
Step three, the electrode group 1 starts to be electrified with direct current, metal impurities are removed through oxidation-reduction reaction on the positive electrode and the negative electrode, and the direct current voltage of the graphite rod of the electrode group 1 is controlled to be 5V-48V; preferably 10V to 24V.
In the scheme, direct current is started through the graphite electrode, oxidation-reduction reaction is carried out on the positive electrode and the negative electrode, and metal impurities are removed; by adopting an electrolysis mode, metal cations are deposited by reduction reaction at the negative electrode, so that the metal cations have removal effect on all metal ions, have better removal effect on high-valence heavy metal impurities with strong electron obtaining capability, and are more comprehensive in metal ion removal.
Step four, circulating hexachlorodisilane by starting a circulating pump 8, wherein the circulating time is 4-8 hours; the circulating pump 8 uses a diaphragm pump or a gear pump, and the circulating flow is 10L/h-200L/h, preferably 50L/h-100L/h; hexachlorodisilane material volume is cycled per hour: the volume of the electrolytic impurity removing tank 2 is 0.5:1-2:1.
According to the scheme, the 8-row circulation of the circulating pump is started, the probability of reduction deposition of metal impurities on the negative electrode is improved, the impurity removal efficiency is improved, and the circulation time is 4-8 hours.
Step five, generating a small amount of HCl and Cl 2 by oxidation at the positive electrode of the electrode group 1, discharging from the exhaust port 6 when the pressure of the electrolytic impurity removal tank 2 is higher than the set pressure, and absorbing by the alkaline washing unit 9;
For example, the pressure in the electrolytic impurity removing tank 2 is controlled to be 40 kPa-50 kPa, the pressure is higher than 50kPa, the exhaust port 6 is opened to exhaust air, the pressure is lower than 40kPa, and the exhaust port 6 is closed dynamically to maintain pressure; during the electrolysis process, the anode is oxidized to generate a small amount of HCl and Cl 2, and after the pressure is higher than the set pressure, the anode is discharged from the top exhaust port 6 and is absorbed by alkaline washing.
And step six, after circulation for 4 to 8 hours, collecting and detecting products through the liquid outlet 4 of the electrode impurity removal tank 2.
The invention provides a purification method and a device of hexachlorodisilane, which uses a byproduct of a polysilicon system as a raw material, and after the material with high metal impurity content is pressurized by a circulating pump 8, the material continuously circulates through an electrolytic impurity removing tank 2, oxidation reduction reaction occurs on the surface of a graphite rod electrode, metal cations obtain electrons at a negative electrode, the electrons are reduced into metal simple substances, and the metal simple substances are deposited on the surface of the electrode for removal; the anions are oxidized at the positive electrode to generate HCl and Cl 2, and the HCl and Cl 2 are discharged through a tail gas discharge port 6 at the top of the electrolytic impurity removing tank 2. Through cyclic electric impurity removal, the content of metal impurities in hexachlorodisilane is obviously reduced, the content of each metal impurity can be reduced to below 20ppb, the product quality is greatly improved, the loss of production links is small, and the production cost is obviously reduced.
The following description is made with reference to specific embodiments:
Example 1
Step one, before feeding, the electrolytic impurity removing tank 2 is filled with high-purity inert gas through a protective gas interface 5 to replace the electrolytic impurity removing tank 2, the pressure in the electrolytic impurity removing tank 2 is kept at 40-50 kPa, the internal temperature is controlled at 25 ℃, and air and moisture are prevented from entering; the pressure of the electrolytic impurity removing tank is controlled to be 40-50 kPa, the pressure is higher than 50kPa, the air is discharged by automatically opening the air outlet 6, the pressure is lower than 40kPa, and the air outlet 6 is automatically closed; the high-purity inert gas is nitrogen, the purity is more than or equal to 5N, the moisture is less than or equal to 10ppb, the oxygen is less than or equal to 10ppb, and the nitrogen is replaced to be qualified;
Step two, hexachlorodisilane to be treated with high metal impurity content is added through a liquid adding port 3 of the electrolytic impurity removing tank 2; the volume of the added hexachlorodisilane is 90% of the volume of the electrolytic impurity removal tank 2; the electrolytic impurity removing tank 2 is made of 316L and has a volume of 100L, and the inner surface is lined with PTFE; the addition volume is 90L;
step three, the electrode group 1 starts to be electrified with direct current, metal impurities are removed through oxidation-reduction reaction on the positive electrode and the negative electrode, the materials of the positive electrode and the negative electrode are graphite, the positive electrode and the negative electrode of each electrolytic impurity removing groove 2 are 4 groups, and graphite rods of each group of electrode groups are 4 pairs; electrode direct current voltage control 24V;
And fourthly, circulating hexachlorodisilane by starting a circulating pump 8, wherein the circulating pump 8 adopts a diaphragm metering pump, the circulating flow is 100L/h, the circulating time is 6h, sampling and detection are carried out through a liquid outlet 4, and the metal impurities are detected by adopting ICP-MS.
Step five, generating a small amount of HCl and Cl 2 by oxidation at the positive electrode of the electrode group 1, discharging from the exhaust port 6 after the pressure of the electrolytic impurity removal tank 2 is higher than the set pressure of 50kPa, and absorbing by the alkaline washing unit 9;
And step six, after circulation for 6 hours, collecting products through a liquid outlet 4 of the electrode impurity removal tank 2, sampling and detecting through the liquid outlet 4, and detecting metal impurities by adopting ICP-MS.
Example 1 (comparison of before and after electrolytic Elimination)
As can be seen from Table 1, the method of the invention has obvious purification effect on hexachlorodisilane raw materials with higher impurity content, after electrolytic treatment, various impurities are obviously reduced, and the content of Al impurity with highest content is lower than 20ppb.
TABLE 2 examples 1-3 and comparative example 1 (cycle time vs)
In comparison with example 1, sample 1 in table 2 is identical to example 1 in terms of the cycle time for 6 hours, examples 2, 3 and comparative example 1 being identical to the other conditions of example 1, except that: sample 2 (example 2) had a cycle time of 4h, sample 3 (example 3) had a cycle time of 8h, and sample 4 (comparative example) had a cycle time of 2h.
As can be seen from Table 2, the removal efficiency of the metal impurities in examples 1 to 3 was gradually increased with the increase of the cycle time, and the decrease of the efficiency was more remarkable with the decrease of the cycle time in comparative example 1, but the production efficiency was decreased with the excessively long cycle time, and the proper cycle electrolysis time was selected according to the requirements of the product quality.
TABLE 3 examples 1, 4-6 (comparison of circulation flow rates)
In comparison with example 1, sample 1 in Table 3 was identical in terms of example 1, and had a circulating flow rate of 100L/h.
Examples 4, 5 and 6 are identical to example 1 except that: sample 2 (example 4) had a circulation flow of 10L/h, sample 3 (example 5) had a circulation flow of 200L/h, sample 4 (example 6) had a circulation flow of 400L/h, and the other conditions were the same.
As can be seen from table 3, sample 2 had a too small circulation flow, decreased circulation times per unit time, decreased probability of reduction of metal cations on electrolysis, and decreased impurity removal effect; however, the excessive circulation flow of the sample 4 can cause the too fast flow rate of the material, the impact on the electrode is increased, and deposited impurities are fallen off, so that the circulation flow is controlled in a proper interval, and the circulation volume of the solution per hour is preferably controlled: the electrolytic stripping tank volume=0.5:1-2:1 is preferable.
TABLE 4 examples 1, 7, 8 and comparative example 2 (electrolytic voltage vs.)
Sample 1 in table 4 is identical to example 1 in terms of electrolysis voltage of 24V compared to example 1, and examples 7, 8 and comparative example 2 are identical to example 1 except that: the electrolysis voltage of sample 2 (example 7) was 5V, the electrolysis voltage of sample 3 (example 8) was 48V, the electrolysis voltage of sample 4 (comparative example 2) was 2V, and the other conditions were the same.
As can be seen from table 4, the lower electrode voltage of comparative example 2 resulted in slower redox reaction at the electrode, and the reduction of the impurity removal effect was significant; in example 8, after the voltage is raised, the impurity removing effect of the electrolytic impurity removing tank is increased, but the safety risk is raised and the production cost is raised due to the excessively high voltage, preferably 10V to 24V.
According to the invention, the metal impurities in the hexachlorodisilane are removed through the electrolytic stripping tank, and by controlling the proper circulation time, selecting the proper circulation flow according to the volume of the electrolytic stripping tank 2 and selecting the proper electrode voltage, various metal impurities in the hexachlorodisilane can be efficiently removed, and particularly, the removal effect is more obvious for metal impurities with higher content such as Al, ti, cr, fe, cu. Compared with the existing purification methods such as rectification, adsorption, extraction, ionization chlorination and the like, other impurity components are not introduced, the metal impurities are comprehensively removed, the removal rate is high, the flow is simple, the overhaul is convenient, and the cost is low.
The present invention is not limited to the above-mentioned embodiments, but is intended to be limited to the following embodiments, and any modifications, equivalent changes and variations in the above-mentioned embodiments can be made by those skilled in the art without departing from the scope of the present invention.
Claims (10)
1. A hexachlorodisilane purification device, characterized in that: comprising
The electrode group is provided with a plurality of groups; the metal impurities are removed through oxidation-reduction reaction on the positive electrode and the negative electrode;
The electrolytic impurity removing tank is of a closed structure, the inside of the electrolytic impurity removing tank is used for installing the electrode groups, and a plurality of electrode groups are sequentially arranged in the electrolytic impurity removing tank along the flow direction of raw materials; the side wall of the electrolytic impurity removing tank is provided with a liquid adding port, a liquid discharging port, a protective gas interface and an air outlet, wherein the liquid adding port is used for introducing hexachlorodisilane raw materials to be treated into the electrolytic impurity removing tank, and the protective gas interface is used for introducing inert gas into the electrolytic impurity removing tank and replacing and protecting the interior of the electrolytic impurity removing tank; the exhaust port is used for exhausting gas generated by electrolysis to the outside of the electrolytic impurity removal tank through the exhaust port; the liquid outlet is used for discharging and collecting products through the liquid outlet after the electrolysis is completed;
The circulating pipeline is respectively communicated with a circulating liquid inlet and a circulating liquid outlet of the electrolytic impurity removal tank, the circulating liquid inlet and the circulating liquid outlet are respectively arranged on the side walls of the feeding side and the discharging side of the electrode group and are used for realizing that after materials in the electrolytic impurity removal tank are discharged from the circulating liquid outlet side, the materials return to the other end circulating liquid inlet side of the electrolytic impurity removal tank through the circulating pipeline and the circulating liquid inlet;
And the circulating pump is arranged on the circulating pipeline and is used for providing driving force for the circulating flow of hexachlorodisilane raw material.
2. The purification apparatus of hexachlorodisilane of claim 1, wherein: the exhaust port is communicated with the alkaline washing unit and is used for carrying out alkaline washing treatment on hydrogen chloride and chlorine generated by electrolysis.
3. The purification apparatus of hexachlorodisilane of claim 1, wherein: the electrode groups are provided with 2-6 groups.
4. The purification apparatus of hexachlorodisilane of claim 1, wherein: PTFE or PFA inner liner layer is arranged on the inner wall of the electrolytic impurity removal tank.
5. A hexachlorodisilane purification apparatus as recited in claim 3, wherein: the electrode group comprises a positive electrode and a negative electrode, and both the positive electrode and the negative electrode adopt graphite rods.
6. The apparatus for purifying hexachlorodisilane of claim 5, wherein: the number of graphite rods of each group of electrode groups is 2-8 pairs.
7. A method for purifying hexachlorodisilane is characterized in that: the method comprises the following specific steps:
Step one, before feeding, the electrolytic impurity removing tank is replaced by introducing high-purity inert gas through a protecting gas port, so that air and moisture are prevented from entering, the pressure in the electrolytic impurity removing tank is kept between 10 and 100kPa, and the internal temperature is controlled between 10 and 50 ℃;
Step two, hexachlorodisilane to be treated with high metal impurity content is added through a liquid adding port of an electrolytic impurity removing tank; the volume of the added hexachlorodisilane is 85% -95% of the volume of the electrolytic impurity removal tank;
Step three, the electrode group starts to be electrified with direct current, metal impurities are removed through oxidation-reduction reaction on the positive electrode and the negative electrode of the electrode group, and the direct current voltage of the graphite rod of the electrode group is controlled to be 5-48V;
step four, circulating hexachlorodisilane by starting a circulating pump, wherein the circulating time is 4-8 hours;
Step five, generating a small amount of HCl and Cl 2 through oxidation at the positive electrode of the electrode group, discharging from an exhaust port after the pressure of the electrolytic impurity removing tank is higher than a set pressure, and absorbing by an alkaline washing unit;
and step six, collecting and detecting products through a liquid outlet of the electrode impurity removal tank after the cycle time of the electrolytic impurity removal tank reaches 4-8 hours.
8. The method for purifying hexachlorodisilane of claim 7, wherein: in the first step, the pressure in the electrolytic impurity removing tank is 30 kPa-60 kPa, and the internal temperature is controlled at 20-40 ℃.
9. The method for purifying hexachlorodisilane of claim 7, wherein: in the third step, the direct current voltage of the graphite rod of the electrode group is controlled to be 10V-24V.
10. The method for purifying hexachlorodisilane of claim 7, wherein: in the fourth step, the circulating pump circulates hexachlorodisilane material volume per hour: the volume of the electrolytic impurity removing tank is 0.5:1-2:1.
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