Method and device for removing metal impurities in tungsten hexafluoride by using fluorine gas

Abstract

The invention provides a method for removing metal impurities in tungsten hexafluoride by fluorine gas, which comprises the following steps: contacting fluorine gas with crude tungsten hexafluoride, carrying out oxidation reaction on fluorine gas and the metal impurities in the crude tungsten hexafluoride to finally form a plurality of metal fluorides, and carrying out two-stage separation on tungsten hexafluoride and a mixture of residual fluorine gas and metal fluorides, residual fluorine gas, metal fluoride and high-purity tungsten hexafluoride are obtained respectively, the separated high-purity tungsten hexafluoride is collected after heat exchange, and finally removal of metal impurities in tungsten hexafluoride is completed. The invention also relates to a device for removing metal impurities in tungsten hexafluoride by using fluorine gas, which comprises a reactor, the reactor is connected with a first-stage separator, the first-stage separator is connected with a second-stage separator, the second-stage separator is connected with a heat exchanger, and the heat exchanger is connected with a collector. The purity of tungsten hexafluoride can reach 99.9%, and the limitation of the purity of crude gas is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine-containing fine chemical synthesis, and specifically relates to a method and a device for removing metal impurities in tungsten hexafluoride by using fluorine gas. Background Art

[0002] Tungsten hexafluoride is an electronic gas widely used in the field of ultra-large-scale circuits and semiconductor materials. As the main raw material for the chemical vapor deposition (CVD) process, tungsten hexafluoride is the main chemical gas used to manufacture large-scale integrated circuits. Its purity is required to be high, often above 99.99%. At present, the industry mostly uses fluorine gas and metal tungsten powder for gas-solid reaction to prepare tungsten hexafluoride, but it is limited by the purity of metal tungsten powder, resulting in the purity of the prepared product far from meeting the specification requirements. There are two main methods for purifying tungsten hexafluoride: adsorption purification and distillation purification.

[0003] Chinese patent CN10827788B is a method and apparatus for producing high-purity tungsten hexafluoride. It discloses a method for obtaining high-purity tungsten hexafluoride by removing substantially all highly volatile gas impurities and thorny transition metal impurities using carbon-containing materials. The purity of the product obtained by this method is above 99.99%, but there are problems such as high requirements on the ratio of the three compounds used and complex process conditions, making it difficult to achieve large-scale production.

[0004] Chinese patent CN104973629B discloses a method for purifying tungsten hexafluoride gas, which discloses a method for removing hydrogen fluoride and metal impurities in tungsten hexafluoride by heating nitrogen replacement equipment, distillation tower impurity removal and other operations. This method has the problems of high reaction system pressure and a single type of metal impurities to be removed.

[0005] Chinese patent CN113574020B discloses a method for manufacturing tungsten hexafluoride, a method for purifying tungsten hexafluoride, and tungsten hexafluoride. The method comprises reacting arsenic or an arsenic compound with a fluorine-containing compound gas, and then separating and removing the trivalent arsenic compound through distillation and other processes to obtain tungsten hexafluoride. The tungsten hexafluoride obtained by this method has a high purity, but the arsenic or arsenic compound used contains highly toxic elements, which greatly increases the dangerous characteristics of the system.

[0006] In summary, the methods for purifying tungsten hexafluoride in existing patents and literature have the problems of complex system raw material ratios and cumbersome subsequent processing operations. Summary of the invention

[0007] In order to solve the problem that metal impurities in crude tungsten hexafluoride are difficult to be completely and effectively removed, the present invention provides a method and device for removing metal impurities in tungsten hexafluoride by using fluorine gas to improve the purity of tungsten hexafluoride.

[0008] The technical solution adopted by the present invention is:

[0009] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, comprising: contacting fluorine gas with crude tungsten hexafluoride, performing an oxidation reaction between the fluorine gas and the metal impurities in the crude tungsten hexafluoride to form metal fluoride, performing two-stage separation on the tungsten hexafluoride, a mixture of residual fluorine gas and metal fluoride to obtain residual fluorine gas, metal fluoride and high-purity tungsten hexafluoride respectively, collecting the separated high-purity tungsten hexafluoride after heat exchange, and finally completing the removal of metal impurities in tungsten hexafluoride.

[0010] Preferably, the specific steps of contacting the fluorine gas with the crude tungsten hexafluoride are: preheating the crude tungsten hexafluoride to 100-150° C., and then performing an oxidation reaction with the fluorine gas.

[0011] Preferably, the temperature of the oxidation reaction is 100°C to 250°C, the pressure is 0.05-0.15 MPa, the primary separation temperature is controlled at 30°C to 35°C, the secondary separation temperature is controlled at 20 to 25°C, and the heat exchange temperature is controlled at 7°C to 10°C.

[0012] Preferably, the product gas components are analyzed by gas chromatography, and the metal ion components are determined by ICP-MS.

[0013] Preferably, the purity of tungsten hexafluoride in the crude tungsten hexafluoride is below 95%, and the mass ratio of the crude tungsten hexafluoride to fluorine gas is 5:2.

[0014] Preferably, the purity of fluorine gas is not less than 99.9%, which is helpful to stimulate the reaction between fluorine gas and metal impurities, and the separation efficiency of metal impurities in tungsten hexafluoride reaches more than 99.9%, among which the separation efficiency of Na, K, Cr, Fe and Zn is more than 99.93%.

[0015] Preferably, the residual fluorine gas after the separation of the two poles is directly used as a reaction raw material to react and produce crude tungsten hexafluoride, thereby avoiding the problem of fluorine gas recovery caused by excessive introduction of fluorine gas.

[0016] Preferably, the collector temperature is controlled between -40 and -140° C. The collector yield is the highest, reaching more than 99%.

[0017] A device for removing metal impurities in tungsten hexafluoride by using fluorine gas comprises a reactor, wherein the reactor is connected to a primary separator, the primary separator is connected to a secondary separator, the secondary separator is connected to a heat exchanger, and the heat exchanger is connected to a collector.

[0018] Preferably, the reactor is also connected to a mass flow meter;

[0019] The reactor is a vertical tube reactor;

[0020] The heat exchanger is a shell and tube heat exchanger;

[0021] The reactor, the primary separator and the secondary separator are made of monel alloy, and the heat exchanger, the collector and the connected pipes are made of stainless steel.

[0022] Preferably, when in use, first turn on the reactor heating to preheat the crude tungsten hexafluoride. When the reactor temperature rises to the required temperature, open the valves of the fluorine gas inlet mass flow meter, heat exchanger, and collector at the same time. After the collector is full, the tungsten hexafluoride is vaporized and continuously monitored by gas chromatography.

[0023] The beneficial effects obtained by the present invention are:

[0024] The present invention continuously introduces F2 into crude tungsten hexafluoride to fluorinate metal impurities to generate high-boiling-point metal fluorides, thereby ultimately removing metal impurities. The purity of tungsten hexafluoride can reach 99.9% or above, thus solving the limitation of crude gas purity.

[0025] The present invention removes metal impurities carried in tungsten hexafluoride by introducing fluorine gas of a certain purity into crude tungsten hexafluoride. The fluorine gas can indirectly participate in the reaction as a fluorinating agent, thereby effectively avoiding the subsequent treatment operation of the fluorine gas.

[0026] The present invention mainly introduces fluorine gas of a certain purity into crude tungsten hexafluoride and realizes continuous operation of purifying tungsten hexafluoride by adjusting the intake gas velocity of the fluorine gas. The process operation is simple and the reaction efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Explanation of the reference numerals: 1. mass flow meter, 2. reactor, 3. primary separator, 4. secondary separator, 5. heat exchanger, 6. collector. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] Two samples of crude tungsten hexafluoride are taken, namely sample 1 and sample 2. The metal impurity contents in the crude tungsten hexafluoride samples 1 and 2 are shown in Table 1 below.

[0031] Table 1 Metal impurity content in crude tungsten hexafluoride

[0032] index Sample before separation 1 / ppb Sample before separation 2 / ppb Na 4128 4384 Mg 3164 3016 K 1058 1.717 Ca 3153 3217 Cr 492 513 Mn 172 146 Fe 2194 2671 Co 16 38 Ni 293 398 Cu 219 16 Zn 39 89 Mo 121 47 Cd 16 2 Pb 17 52

[0033] The purity of sample 1 before separation was 94.50%, and the purity of sample 2 was 94.58%.

[0034] like Figure 1 As shown, a device for removing metal impurities in tungsten hexafluoride by fluorine gas includes a reactor 2, the front end of the reactor 2 is connected to a mass flow meter 1, the reactor is connected to a primary separator 3, the primary separator 3 is connected to a secondary separator 4, the secondary separator 4 is connected to a heat exchanger 5, and the heat exchanger 5 is connected to a collector 6.

[0035] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, comprising: preheating crude tungsten hexafluoride to 100-150° C., introducing crude tungsten hexafluoride and fluorine gas into a reactor 2 through a mass flow meter 1, wherein the mass ratio of crude tungsten hexafluoride to fluorine gas is 5:2, reacting fluorine gas with metal impurities in the reactor, oxidizing and combining fluorine gas with various metal impurities in tungsten hexafluoride to finally form a variety of metal fluorides, conveying a mixture of tungsten hexafluoride and metal fluorides to a primary separator 3 and a secondary separator 4 for separation, and passing the separated high-purity tungsten hexafluoride through a heat exchanger 5 and then entering a collector 6, thereby finally completing the removal of metal impurities in tungsten hexafluoride.

[0036] Example 1

[0037] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, wherein the gas velocity of the fluorine gas is 2 m / s, the purity of the fluorine gas is 99.9%, the gas velocity of the crude tungsten hexafluoride is 3 m / s, and the content of the tungsten hexafluoride components in the collector after the reaction is shown in Table 2 below.

[0038] The pressure in the reactor is controlled at 0.1 MPa and 100°C. The product continuously passes through a primary separator (30°C), a secondary separator (20°C) and a shell-and-tube heat exchanger (7°C) into a collector. The collection temperature of the collector is -40 to -140°C. The impurity content is reduced by 99.91% through actual analysis and comparative calculation. The metal ion components are characterized by ICP-MS gas, and comparative analysis is performed before and after separation.

[0039] Table 2 Metal impurity content in products

[0040] index After separation, the sample is 1 / ppb After separation, sample 2 / ppb Na 4.328 4.168 Mg 2.195 2.268 K 1.049 0.717 Ca 2.986 1.338 Cr 0.483 0.323 Mn 0.110 0.128 Fe 1.876 2.916 Co 0.016 0.028 Ni 0.290 0.361 Cu 0.202 0.128 Zn 0.493 0.867 Mo 0.1098 0.051 Cd 0.012 0.005 Pb 0.011 0.040

[0041] After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.991%, and the purity of sample 2 was 99.993%.

[0042] Example 2

[0043] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, wherein the gas velocity of the fluorine gas is 3 m / s, the purity of the fluorine gas is 99.9%, the gas velocity of the crude tungsten hexafluoride is 4 m / s, and the content of the tungsten hexafluoride components in the collector after the reaction is shown in Table 3 below.

[0044] The pressure in the reactor is controlled at 0.05 MPa and 150°C. The product continuously passes through a primary separator (35°C), a secondary separator (25°C) and a shell-and-tube heat exchanger (10°C) into a collector. The collection temperature of the collector is -40 to -140°C. The impurity content is reduced by 99.93% through actual analysis and comparison calculation. The metal ion components are characterized by gas through ICP-MS.

[0045] Table 3 Gas impurity content in products

[0046]

[0047]

[0048] After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.995%, and the purity of sample 2 was 99.994%.

[0049] Example 3

[0050] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, wherein the gas velocity of the fluorine gas is 4 m / s, the purity of the fluorine gas is 99.9%, the gas velocity of the crude tungsten hexafluoride is 5 m / s, and the content of the tungsten hexafluoride components in the collector after the reaction is shown in Table 4 below.

[0051] The pressure in the reactor is controlled at 0.15 MPa and 200°C. The product continuously passes through the primary separator (32°C), the secondary separator (23°C) and the shell-and-tube heat exchanger (8°C) into the collector. The collection temperature of the collector is -40 to -140°C. The impurity content is reduced by 99.94% through actual analysis and comparison calculation. The metal ion components are characterized by ICP-MS determination of gas.

[0052] Table 4 Gas impurity content in the product

[0053] index After separation, the sample is 1 / ppb After separation, sample 2 / ppb Na 3.145 2.069 Mg 2.085 2.218 K 1.009 0.708 Ca 2.966 1.329 Cr 0.418 0.319 Mn 0.115 0.108 Fe 1.592 1.516 Co 0.014 0.021 Ni 0.282 0.321 Cu 0.213 0.119 Zn 0.329 0.582 Mo 0.108 0.037 Cd 0.012 0.005 Pb 0.037 0.031

[0054] After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.996%, and the purity of sample 2 was 99.995%.

[0055] Example 4

[0056] A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, wherein the gas velocity of the fluorine gas is 5 m / s, the purity of the fluorine gas is 99.9%, the gas velocity of the crude tungsten hexafluoride is 6 m / s, and the content of the tungsten hexafluoride components in the collector after the reaction is shown in Table 5 below.

[0057] The pressure in the reactor is controlled at 0.1 MPa and 250°C. The product continuously passes through the primary separator (33°C), the secondary separator (22°C) and the shell-and-tube heat exchanger (9°C) into the collector. The collection temperature of the collector is -40 to -140°C. The impurity content is reduced by 99.95% through actual analysis and comparison calculation. The metal ion components are characterized by ICP-MS determination of gas.

[0058] Table 5 Impurity content in products

[0059] index After separation, the sample is 1 / ppb After separation, sample 2 / ppb Na 3.165 2.058 Mg 2.075 2.209 K 1.007 0.785 Ca 2.851 1.159 Cr 0.409 0.382 Mn 0.110 0.116 Fe 1.467 1.519 Co 0.012 0.013 Ni 0.273 0.313 Cu 0.215 0.117 Zn 0.316 0.549 Mo 0.114 0.037 Cd 0.011 0.004 Pb 0.036 0.028

[0060] After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.999%, and the purity of sample 2 was 99.998%.

[0061] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for removing metal impurities in tungsten hexafluoride by using fluorine gas, characterized in that: The fluorine gas is brought into contact with the crude tungsten hexafluoride, and metal impurities in the crude tungsten hexafluoride are oxidized to form metal fluoride. The tungsten hexafluoride, the mixture of residual fluorine gas and metal fluoride are separated in two stages to obtain residual fluorine gas, metal fluoride and high-purity tungsten hexafluoride respectively. The separated high-purity tungsten hexafluoride is collected after heat exchange, and finally the metal impurities in the tungsten hexafluoride are removed.

2. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The specific steps of contacting the fluorine gas with the crude tungsten hexafluoride are: preheating the crude tungsten hexafluoride to 100-150° C., and then carrying out an oxidation reaction with the fluorine gas.

3. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The temperature of the oxidation reaction is 100°C to 250°C, the pressure is 0.05-0.15MPa, the primary separation temperature is controlled at 30°C to 35°C, the secondary separation temperature is controlled at 20°C to 25°C, and the heat exchange temperature is controlled at 7°C to 10°C.

4. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The product gas components were analyzed by gas chromatography, and the metal ion components were determined by ICP-MS.

5. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The purity of tungsten hexafluoride in the crude tungsten hexafluoride is below 95%, and the mass ratio of crude tungsten hexafluoride to fluorine gas is 5:

2.

6. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The purity of fluorine gas is not less than 99.9%.

7. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The residual fluorine gas after the separation of the two electrodes is directly used as a reaction raw material to react and produce crude tungsten hexafluoride.

8. The method for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 1, characterized in that: The collector temperature is controlled between -40 and -140°C.

9. A device for removing metal impurities in tungsten hexafluoride by using fluorine gas, used in the method for removing metal impurities in tungsten hexafluoride by using fluorine gas as claimed in claim 1, characterized in that: The invention comprises a reactor, wherein the reactor is connected to a primary separator, the primary separator is connected to a secondary separator, the secondary separator is connected to a heat exchanger, and the heat exchanger is connected to a collector.

10. The device for removing metal impurities in tungsten hexafluoride by using fluorine gas according to claim 9, characterized in that: The reactor is also connected to a mass flow meter; The reactor is a vertical tube reactor; The heat exchanger is a shell and tube heat exchanger; The reactor, the primary separator and the secondary separator are made of monel alloy, and the heat exchanger, the collector and the connected pipes are made of stainless steel.

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