JP2007176770A - Method of producing high purity fluorine gas and apparatus for producing high purity fluorine gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing high purity fluorine gas used, for example, as an etching gas and a cleaning gas for the manufacture of a semiconductor or a liquid crystal and an apparatus for producing the high purity fluorine gas which is used for the production method. <P>SOLUTION: The method of producing the high purity fluorine gas is carried out by treating manganese fluoride with a process including a step (1) for reducing the pressure while heating manganese fluoride at 250-340°C, a step (2) for releasing fluorine gas while heating the manganese fluoride at 340-500°C under the reduced pressure, a step (3) for bringing the manganese fluoride into contact with fluorine gas while heating the manganese fluoride at 340-500°C then reducing the pressure and a step (4) for absorbing fluorine gas, and the resultant manganese fluoride is heated to produce the high purity fluorine gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing high-purity fluorine gas by heating manganese fluoride and a high-purity fluorine gas production apparatus used therefor. More specifically, a method for producing high-purity fluorine gas by heating manganese fluoride obtained by removing impurities such as silicon component and carbon component contained in manganese fluoride as silicon fluoride or carbon fluoride and The present invention relates to a purity fluorine gas production apparatus.

Fluorine gas is used as a raw material for synthesizing various fluorides, and recently has begun to be used as a cleaning gas and etching gas for electronic parts such as semiconductors and liquid crystals. General industrial production of fluorine gas is performed by electrolysis of KF · 2HF molten salt. The fluorine gas obtained by this method may contain impurity gases derived from electrodes and raw materials such as HF, O ₂ , N ₂ , CO ₂ , CF ₄ , SiF _4, etc., and a high-purity fluorine gas is obtained. However, it is necessary to remove these impurity gases, but it is not easy. For example, among these impurity gases, HF can be removed relatively easily by using porous NaF, but other impurity gases need to be repeatedly distilled and purified. However, fluorine is a highly active substance, and it is very dangerous to repeat the process of liquefaction and gasification for distillation purification, and it is difficult to implement industrially. In addition, the fluorine electrolytic cell is difficult to maintain and stably operate. In addition to this, the material of the distillation tower is also very disadvantageous because it requires a very expensive material resistant to fluorine and requires distillation at a very low temperature. Furthermore, since ancillary facilities are required, the capital investment is high, and the fluorine gas becomes very expensive if there is no amount of use, so far it has been difficult to supply inexpensive high-purity fluorine gas.

  In addition, fluorine gas is the most oxidative combustion-supporting gas, and is highly toxic and highly corrosive to materials. Therefore, in Japan, except for special cases, it is almost circulated as a compressed gas cylinder that is not diluted on a commercial basis. Not.

  As a method for supplying fluorine gas other than a cylinder, Japanese Patent Application Laid-Open No. 5-502981 (Patent Document 1) stores fluorine gas in a solid state and stores the solid when fluorine gas is used. A fluorine gas generator is disclosed in which a container is heated to generate fluorine gas by the reaction of the following formula (1).

K ₃ NiF ₇ → K ₃ NiF ₆ + 1 / 2F ₂ (1)
Although this document does not discuss the purity of fluorine gas, K ₃ NiF ₇ contains a small amount of impurities such as silicon component and carbon component. It is considered that carbons may be mixed as impurities in the fluorine gas.

Further, as metal fluoride capable of generating fluorine gas, CoF ₃ and MnF ₄ are known, but the fluorine gas generation temperature from CoF ₃ is 500 ° C. or more, and there are restrictions on the material of the device, etc. It is difficult to use industrially. On the other hand, although the fluorine gas generation temperature of MnF ₄ is lower than that of CoF ₃ , the purity of the generated fluorine gas and the high purity of the fluorine gas have not been studied so far. For example, US Pat. No. 143,0011 (Patent Document 2) describes a method of using manganese fluoride as a fluorine gas generating agent, but purity is not studied. In addition, this method generates a small amount of fluorine gas, and manganese fluoride contains trace amounts of impurities such as silicon components and carbon components. Silicon fluorides and fluorocarbons derived from these impurities are contained in fluorine gas. It is conceivable to be mixed in as impurities.

  Furthermore, the silicon component and carbon component contained in the high-valent metal fluoride used as the fluorine gas generator in these methods are the raw materials used to synthesize the high-valent metal fluoride and the material of the container used. It is difficult to synthesize metal fluoride so as not to contain these impurities.

Thus, it has not been studied so far to obtain a high-purity fluorine gas having a small content of silicon fluorides and fluorocarbons. However, in the field of electronic industries such as semiconductors, microfabrication is progressing year by year, and the development of technology that uses fluorine gas as an etching gas is also progressing. Furthermore, fluorine gas is a gas with a low global warming potential. Use as a cleaning gas for the CVD chamber is also expected. Since impurities in the fluorine gas deteriorate the product yield and reduce the production efficiency, a high-purity fluorine gas with a low impurity content is required.
Japanese National Patent Publication No. 5-502981 Soviet Patent No. 143001

  The present invention is intended to solve the problems associated with the prior art as described above, and the problem to be solved is, for example, a high level that can be used as an etching gas and a cleaning gas when manufacturing semiconductors and liquid crystals. An object of the present invention is to provide a method for producing a pure fluorine gas and a high-purity fluorine gas production apparatus that can be used in this production method.

  As a result of earnest research to solve the above problems, the present inventor has preliminarily set manganese fluoride to a temperature at which the fluorine gas generation pressure becomes atmospheric pressure or lower when the manganese fluoride is heated to generate fluorine gas. The silicon component contained in manganese fluoride is removed as silicon fluorides under reduced pressure while heating, and then the carbon component contained in manganese fluoride reacts with fluorine by heating manganese fluoride in the presence of fluorine gas. By removing them as fluorocarbons, the inventors have found that the generated fluorine gas has a low content of silicon fluorides and fluorocarbons and has high purity, and thus completed the present invention.

That is, the present invention includes the following [1] to [13].
[1] Step of depressurizing manganese fluoride while heating to 250 to 340 ° C., (2) Step of releasing fluorine gas while heating to 340 to 500 ° C. under reduced pressure, (3) 340 to 500 It is processed by a method including a step of reducing pressure after contacting with fluorine gas while heating to ° C., and (4) a step of absorbing fluorine gas, and heating the obtained manganese fluoride to convert high purity fluorine gas A method for producing high-purity fluorine gas, characterized in that it is generated.

[2] The method for producing high-purity fluorine gas according to [1], wherein the manganese fluoride is represented by an average composition formula MnF _x (3 <x ≦ 4).
[3] The method for producing high-purity fluorine gas according to the above [1] or [2], wherein in the step (1), the absolute pressure is reduced to 0.005 MPa or less.

[4] The method for producing high-purity fluorine gas according to any one of the above [1] to [3], wherein in the step (2), the absolute pressure is reduced to 0.005 MPa or less.
[5] In any one of the above [1] to [4], in the step (3), the pressure when contacting with the fluorine gas is 0.1 MPa or more and 1.0 MPa or less in absolute pressure. Of high purity fluorine gas.

[6] The method for producing high-purity fluorine gas according to any one of [1] to [5], wherein the step (3) is repeated twice or more.
[7] Fluorine gas is absorbed into manganese fluoride after being used in the production method according to any one of [1] to [6], and the resulting manganese fluoride is heated to produce high-purity fluorine gas. A method for producing high-purity fluorine gas, characterized in that it is generated.

  [8] (1) Step of depressurizing while heating to 250 to 340 ° C, (2) Step of releasing fluorine gas while heating to 340 to 500 ° C under reduced pressure, (3) While heating to 340 to 500 ° C An apparatus for producing high-purity fluorine gas, comprising manganese fluoride treated by a method comprising: a step of reducing pressure after contacting with fluorine gas; and (4) a step of absorbing fluorine gas.

[9] The high-purity fluorine gas production apparatus according to [8], wherein the manganese fluoride is represented by an average composition formula MnF _x (3 <x ≦ 4).
[10] The high-purity fluorine gas production apparatus according to [8] or [9], wherein in the step (1), the absolute pressure is reduced to 0.005 MPa or less.

[11] The high-purity fluorine gas production apparatus according to any one of [8] to [10], wherein in the step (2), the absolute pressure is reduced to 0.005 MPa or less.
[12] In any one of the above [8] to [11], in the step (3), the pressure when contacting with the fluorine gas is 0.1 MPa or more and 1.0 MPa or less in absolute pressure. High purity fluorine gas production equipment.

  [13] The high-purity fluorine gas production apparatus according to any one of [8] to [12], wherein the step (3) is repeated twice or more.

  According to the present invention, high-purity fluorine gas can be produced inexpensively, safely and industrially. Furthermore, manganese fluoride once treated by the method used in the present invention may be used again for the production of high purity fluorine gas by occluding the fluorine gas even if it was used for the production of high purity fluorine gas. it can.

The present invention will be described in detail below.
Manganese fluoride used in the present invention is a conventionally known manganese fluoride, and can be prepared by a conventionally known method. For example, by fluorinating manganese or a manganese salt with a fluorinating agent such as HF. Further, high-valent manganese fluoride obtained by treating the obtained fluoride with a fluorinating agent having strong oxidizing power can be used. Manganese fluoride prepared by such a conventional method includes impurities such as a silicon component and a carbon component as described above.

Further, in the present invention, among the conventionally known manganese fluorides described above, the amount of fluorine gas generated by heating increases, specifically, the fluorine gas generation rate with respect to manganese fluoride is 10% by mass or more. Valent manganese fluoride is preferable, and manganese fluoride represented _by an average composition formula MnF _x (3 <x ≦ 4) is more preferable. Usually, manganese fluoride MnF _x (3 <x ≦ 4) is obtained as a mixture of crystals represented by MnF ₃ and crystals represented by MnF ₄ . The above average composition formula represents the average composition of such a mixture. For example, in the case of manganese fluoride containing 50% MnF ₃ and 50% MnF ₄ , it is expressed as MnF _3.5 .

The “fluorine gas generation ratio with respect to manganese fluoride” is a value theoretically determined from the fluorine gas generation reaction formula. For example, if the MnF _4, the following formula (2)
MnF ₄ → MnF ₃ + 1 / 2F ₂ (2)
As described above, ½ mol (19 g) of F ₂ is produced from 1 mol (131 g) of MnF ₄ . Therefore, the fluorine gas generation ratio from MnF _{4 is} 19/131 × 100 = 15 mass%.

  In the present invention, the above manganese fluoride is charged into a gas generating container and processed according to the following steps (1) to (4). The capacity | capacitance of a gas generation container can be suitably set with the quantity of the gas generated at the following process. The container material is preferably selected from corrosion-resistant metal materials such as nickel, monel, and stainless steel, and the surface of these metal materials is preferably passivated with fluorine gas in advance. Alternatively, after nickel plating is applied to the surface of the metal material, the surface may be passivated with fluorine gas.

<Step (1)>
First, manganese fluoride containing impurities such as a silicon component and a carbon component is charged into a gas generation container, and the pressure is reduced while heating to 250 to 340 ° C. When the silicon component is contained in the state of a silicon compound such as silicon oxide in manganese fluoride, fluorine gas is generated from the manganese fluoride by the heating, and the fluorine gas reacts with the silicon component to generate silicon fluoride. A kind is generated. In addition, the silicon component may be present in manganese fluoride as a composite fluoride of manganese fluoride and silicon fluoride. When the heating temperature is 250 ° C. or higher, the composite fluoride can be thermally decomposed and removed as silicon fluoride, and the content of the silicon component in manganese fluoride can be reduced. In particular, since manganese fluoride has higher activity as the valence of manganese is higher, a composite fluoride containing manganese having a higher valence is more preferable because it is more easily decomposed by heat. In addition, the higher the heating temperature, the easier the thermal decomposition of the above composite fluoride, but when the heating temperature exceeds 340 ° C, the pressure of fluorine gas generated from manganese fluoride exceeds atmospheric pressure, and more fluorine gas is generated than necessary. However, it is not preferable because the activity of manganese fluoride decreases.

  The silicon fluorides thus produced are removed by the above depressurization operation. The pressure during decompression is preferably 0.005 MPa or less, more preferably 0.002 MPa or less in terms of absolute pressure, from the viewpoint of efficiently removing silicon fluorides. The heating time is preferably 6 hours or longer, more preferably 12 hours or longer.

  By performing heat treatment under reduced pressure as described above, the content of the silicon component in manganese fluoride can be reduced to preferably 100 ppm or less, more preferably 60 ppm or less, and the content of silicon fluorides is reduced. Less fluorine gas can be obtained. The content of the silicon component in manganese fluoride can be quantitatively analyzed by ICP emission spectroscopy after dissolving manganese fluoride in ultrapure water, for example.

<Step (2)>
Next, fluorine gas is released from the manganese fluoride while heating the manganese fluoride from which the silicon component has been removed to 340 to 500 ° C., preferably 380 to 450 ° C. under reduced pressure. As a result, the manganese fluoride can be changed to MnF _3, and even when the manganese fluoride (MnF ₃ ) is heated to a high temperature in the following step (3), high-pressure fluorine gas is not generated, and fluorination can be performed more safely. Manganese (MnF ₃ ) and fluorine can be contacted. On the other hand, if high-valent manganese fluoride (MnF _x (3 <x ≦ 4)) is heated in step (3) without carrying out this step (2), high-pressure fluorine gas is generated, and the pressure resistance of the container is increased. It is necessary to increase the safety, which is not preferable in terms of safety and economy.

The pressure at the time of depressurization is preferably 0.005 MPa or less, more preferably 0.002 MPa or less in terms of absolute pressure, from the viewpoint that the above-mentioned manganese fluoride can be made sufficiently MnF ₃ .
The heating time is appropriately set depending on the heating temperature, but it is preferable to heat until the fluorine gas is not released.

<Step (3)>
The MnF ₃ is brought into contact with fluorine gas while being heated to 340 to 500 ° C., preferably 350 to 450 ° C., more preferably 380 to 450 ° C. As a result, the carbon component in the manganese fluoride reacts with the fluorine gas to produce fluorocarbons. Thereafter, the fluorocarbons are removed by a reduced pressure treatment.

  The heating temperature is preferably higher in terms of promoting the reaction between the carbon component and fluorine. However, exceeding the above range is not preferable because the resistance of the gas generating container decreases. Moreover, the pressure of the fluorine gas at the time of heating contact is preferably 0.1 MPa or more and 1.0 MPa or less in absolute pressure, and more preferably 0.3 MPa or more and 1.0 MPa or less. The heating time is not particularly limited, and can be set as appropriate depending on the degree of progress of the reaction between the carbon component and fluorine.

  The pressure during decompression is preferably 0.005 MPa or less, more preferably 0.002 MPa or less in absolute pressure. Moreover, 340-450 degreeC is preferable and the temperature at this time has more preferable 380-450 degreeC.

  Moreover, it is preferable to repeat the said heating contact and pressure reduction operation 2 times or more, and it is more preferable to repeat 3 times or more. Thereby, the carbon component in manganese fluoride can be removed sufficiently, and a fluorine gas with a low content of fluorocarbons can be obtained.

As described above, the content of the carbon component in the manganese fluoride is preferably 0.02% by mass or less, more preferably 0 by bringing the manganese fluoride into contact with the fluorine gas while heating it to a high temperature and performing a reduced pressure treatment. The fluorine gas can be reduced to 0.005% by mass or less and the content of fluorocarbons is small. The content of the carbon component in the manganese fluoride is determined by, for example, oxidizing the carbon component by heating the manganese fluoride in an oxygen stream and quantifying the generated CO gas and CO ₂ gas by the infrared absorption method. Can be analyzed.

<Process (a)>
In the present invention, in addition to removing the silicon component and the carbon component in the manganese fluoride by performing the above steps (1) to (3), the pressure in the gas generating container is 0.01 MPa or less in absolute pressure. It is preferable to heat manganese fluoride to a temperature of less than 300 ° C. under the following conditions. Thereby, the other impurity gas contained in manganese fluoride can be removed, and a highly purified fluorine gas can be manufactured.

  The heating temperature is more preferably 20 ° C. or higher and lower than 300 ° C., particularly preferably 100 ° C. or higher and lower than 300 ° C. The pressure is more preferably 0.001 MPa or less in absolute pressure. The heating operation is preferably repeated twice or more, more preferably three or more times. Thereby, other impurity gases in manganese fluoride can be sufficiently removed, and a fluorine gas having a small content of other impurity gases can be obtained.

<Process (4)>
Fluorine gas is absorbed into manganese fluoride (MnF ₃ ) from which the silicon component and carbon component have been removed to form high-valent manganese fluoride, specifically MnF _x (3 <x ≦ 4). When MnF ₃ and fluorine gas are brought into contact, for example, MnF ₄ is formed as shown in the following formula (3).

2MnF ₃ + F ₂ → 2MnF ₄ (3)
If the fluorine gas used here is an undiluted fluorine gas having a purity of 95% or more, the preparation method is not particularly limited. For example, fluorine gas generated by electrolysis in an electrolytic cell is passed through NaF to remove hydrogen fluoride, or commercially available fluorine gas filled in a cylinder is passed through NaF to purify fluorine gas, fluorine generation High purity fluorine gas generated by the apparatus can be mentioned. In particular, the content of hydrogen fluoride in the fluorine gas is preferably 500 ppm by volume or less, and more preferably 100 ppm by volume or less. When fluorine gas with a hydrogen fluoride content exceeding the above range is used, hydrogen fluoride is physically adsorbed on manganese fluoride, preventing fluorine gas from being absorbed into manganese fluoride, and hydrogen fluoride is physically adsorbed. Manganese is not preferred because it easily takes in impurity gases such as O ₂ gas, CO ₂ gas, and SiF _4, and it becomes difficult to diffuse and remove these impurity gases even when manganese fluoride is heated.

  In addition to the fluorine gas prepared by the above exemplified method, the fluorine gas released in the above step (2) can also be used in this step if the content of hydrogen fluoride is 500 ppm by volume or less.

The temperature at which MnF ₃ absorbs fluorine gas is preferably 100 to 400 ° C., and the pressure of fluorine gas is preferably 0.2 MPa or more in absolute pressure.
<Production of fluorine gas>
By heating manganese fluoride, preferably MnF _x (3 <x ≦ 4), which has been treated as described above to remove impurities such as silicon component and carbon component, fluorine gas is converted from manganese fluoride to the following formula. Will occur.

2MnF ₄ → 2MnF ₃ + F ₂ (4)
The heating temperature is preferably 340 to 400 ° C, more preferably 360 to 400 ° C, and most preferably 370 to 400 ° C. When the heating temperature is set to 340 ° C. or higher, the generation pressure of the fluorine gas becomes equal to or higher than the atmospheric pressure, the pressure of the fluorine gas generator can be made higher than the pressure of the fluorine gas supply destination, and the supply pressure of the fluorine gas can be easily Can be adjusted. However, since the generation pressure of fluorine gas increases exponentially with respect to the heating temperature, it tends to be high pressure. When the heating temperature exceeds the above range, particularly 450 ° C., high-pressure fluorine gas is generated, which is not preferable in terms of safety, and it is necessary to increase the thickness of the container in order to increase the pressure resistance of the gas generating container. Also, it is not preferable.

The high-purity fluorine gas produced in this way has a low content of hydrogen fluoride, O ₂ , N ₂ , CO ₂ , CF ₄ , SiF ₄ and a purity of 99.9% by volume or more, preferably 99.99. Volume% or more. In particular, the high-purity fluorine gas has a silicon fluoride content of 10 volume ppm or less, a fluorocarbon content of 10 volume ppm or less, and a CO ₂ gas content of 10 volume ppm or less. The content of impurity gas such as silicon fluoride, carbon fluoride, O ₂ gas and CO ₂ gas in the fluorine gas is such that the fluorine gas is occluded in K ₃ NiF ₆ which is a fluoronickel compound and is not occluded. Is obtained by quantitative analysis by gas chromatography. The purity of the fluorine gas is a value obtained by subtracting the impurity gas content from 100% by volume.

<Reuse of manganese fluoride>
As described above, the manganese fluoride (MnF ₃ ) used for the production of the high-purity fluorine gas is again absorbed in the same manner as in the step (4) to obtain a high-valence manganese fluoride. Again, it can be used for the production of high purity fluorine gas.

By repeating this reuse, the content of impurities contained in manganese fluoride is further reduced, and the purity of the generated fluorine gas can be further improved.
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by this Example.

[Reference Example 1]
When the fluorine gas filled in the conventional cylinder was analyzed, its purity was 99.69 vol%, the hydrogen fluoride content was 1500 vol ppm, the O ₂ gas content was 200 vol ppm, and the CO ₂ gas content was The content was 250 ppm by volume, the N ₂ gas content was 500 ppm by volume, the CF ₄ content was 400 ppm by volume, and the SiF ₄ content was 250 ppm by volume.

The fluorine gas production apparatus shown in FIG. 1 was used. 10 kg of untreated MnF _3.8 was charged into a Ni gas generation container 10 (φ150 mm × 1000 mm) having an internal volume of 18 L. After connecting the gas generation container 10 as shown in FIG. 1, the valve 3 and the valve 8 were operated to vacuum-accumulate the connection port of the gas generation container 10 and dry the connection port. Thereafter, the valve 3 was closed and the valve 8 was opened. While the gas generating container 10 was heated to 300 ° C., the pressure was reduced to an absolute pressure of 0.002 MPa by the vacuum pump 11 and this state was maintained for 12 hours (step (1) )).

Subsequently, the inside of the gas generation container 10 was heated to 400 ° C. while reducing the absolute pressure to 0.005 MPa by the vacuum pump 11, and this state was maintained for 6 hours to remove gas generated from MnF _3.8 (step (2)). ). Thereafter, no gas was generated even when the heating was continued. This indicates that MnF _3.8 has changed to MnF ₃ .

  Next, the valve 8 was closed, the valve 4 was opened while the gas generation container 10 was heated to 400 ° C., and fluorine gas was introduced to an absolute pressure of 0.5 MPa, and this state was maintained for 12 hours. At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the valve 4 was closed and the valve 8 was opened, and the generated gas was removed by reducing the pressure in the gas generation container 10 to an absolute pressure of 0.001 MPa by the vacuum pump 11 (step (3)). This step (3) was repeated three times.

Next, the valve 8 is closed, the valve 4 is opened while the gas generating container 10 is heated to 350 ° C., and fluorine gas is introduced into the gas generating container 10 at an absolute pressure of 0.4 MPa while controlling the flow rate by the mass flow controller 5. Fluorine was absorbed in MnF ₃ (step (4)). At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the weight of manganese fluoride in the gas generation container 10 was measured, and it was confirmed that the weight was changed to MnF _3.8 .

The gas generating container 10 charged with MnF _3.8 thus treated was heated to 400 ° C. to produce fluorine gas. When the obtained fluorine gas was analyzed, HF was 50 ppm by volume, CF ₄ was below the detection limit (1 volume ppm or less), and SiF ₄ was below the detection limit (3 volume ppm or less).

[Comparative Example 1]
In the same manner as in Example 1, 10 kg of untreated MnF _3.8 was charged into the gas generation container 10, and then the connection port of the gas generation container 10 was vacuum-accumulated purged and dried. Thereafter, the gas generating container 10 was heated to 400 ° C. to produce fluorine gas. When the obtained fluorine gas was analyzed, HF was 5000 ppm by volume, CF ₄ was 300 ppm by volume, and SiF ₄ was 300 ppm by volume.

[Comparative Example 2]
In the same manner as in Example 1, 10 kg of untreated MnF _3.8 was charged into the gas generation container 10, and then the connection port of the gas generation container 10 was vacuum-accumulated purged and dried. Thereafter, by opening the valve 8 by closing the valve 3, the gas generator vessel 10 and heated in a vacuum while 400 ° C. to an absolute pressure of 0.005MPa with a vacuum pump 11, from MnF _3.8 This state was kept for 6 hours The generated gas was removed (corresponding to step (2) in Example 1). Thereafter, no gas was generated even when the heating was continued. This indicates that MnF _3.8 has changed to MnF ₃ .

Next, the valve 8 is closed, the valve 4 is opened while the gas generating container 10 is heated to 350 ° C., and fluorine gas is introduced into the gas generating container 10 at an absolute pressure of 0.4 MPa while controlling the flow rate by the mass flow controller 5. Fluorine was absorbed in MnF ₃ (corresponding to step (4) in Example 1). At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the weight of manganese fluoride in the gas generation container 10 was measured, and it was confirmed that the weight was changed to MnF _3.8 .

The gas generating container 10 charged with MnF _3.8 thus treated was heated to 400 ° C. to produce fluorine gas. When the obtained fluorine gas was analyzed, HF was 50 ppm by volume, CF ₄ was 40 ppm by volume, and SiF ₄ was 30 ppm by volume.

[Comparative Example 3]
In the same manner as in Example 1, 10 kg of untreated MnF _3.8 was charged into the gas generation container 10, and then the connection port of the gas generation container 10 was vacuum-accumulated purged and dried. Thereafter, by opening the valve 8 by closing the valve 3, the gas generator vessel 10 and heated in a vacuum while 400 ° C. to an absolute pressure of 0.005MPa with a vacuum pump 11, from MnF _3.8 This state was kept for 6 hours The generated gas was removed (corresponding to step (2) in Example 1). Thereafter, no gas was generated even when the heating was continued. This indicates that MnF _3.8 has changed to MnF ₃ .

  Next, the valve 8 was closed, the valve 4 was opened while the gas generation container 10 was heated to 400 ° C., and fluorine gas was introduced to an absolute pressure of 0.5 MPa, and this state was maintained for 12 hours. At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the valve 4 was closed and the valve 8 was opened, and the generated gas was removed by reducing the pressure in the gas generation vessel 10 to an absolute pressure of 0.001 MPa with the vacuum pump 11 (corresponding to step (3) of Example 1). ). This process was repeated three times.

Next, the valve 8 is closed, the valve 4 is opened while the gas generating container 10 is heated to 350 ° C., and fluorine gas is introduced into the gas generating container 10 at an absolute pressure of 0.4 MPa while controlling the flow rate by the mass flow controller 5. Fluorine was absorbed in MnF ₃ (corresponding to step (4) in Example 1). At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the weight of manganese fluoride in the gas generation container 10 was measured, and it was confirmed that the weight was changed to MnF _3.8 .

The gas generating container 10 charged with MnF _3.8 thus treated was heated to 400 ° C. to produce fluorine gas. When the obtained fluorine gas was analyzed, HF was 50 ppm by volume, CF ₄ was below the detection limit (1 ppm by volume), and SiF ₄ was 20 ppm by volume.

[Comparative Example 4]
In the same manner as in Example 1, 10 kg of untreated MnF _3.8 was charged into the gas generation container 10, and then the connection port of the gas generation container 10 was vacuum-accumulated purged and dried. Thereafter, the valve 3 was closed and the valve 8 was opened. While the gas generation container 10 was heated to 300 ° C., the pressure was reduced to an absolute pressure of 0.002 MPa by the vacuum pump 11 and this state was maintained for 12 hours (Example 1). Step (1)).

Subsequently, the inside of the gas generation container 10 was heated to 400 ° C. while reducing the absolute pressure to 0.005 MPa by the vacuum pump 11, and this state was maintained for 6 hours to remove the gas generated from MnF _3.8 (in Example 1). Equivalent to step (2)). Thereafter, no gas was generated even when the heating was continued. This indicates that MnF _3.8 has changed to MnF ₃ .

Next, the valve 8 is closed, the valve 4 is opened while the gas generating container 10 is heated to 350 ° C., and fluorine gas is introduced into the gas generating container 10 at an absolute pressure of 0.4 MPa while controlling the flow rate by the mass flow controller 5. Fluorine was absorbed in MnF ₃ (corresponding to step (4) in Example 1). At this time, as the fluorine gas, the one obtained by passing the fluorine gas in the cylinder through the NaF packed tower 7 and removing HF was used. Thereafter, the weight of manganese fluoride in the gas generation container 10 was measured, and it was confirmed that the weight was changed to MnF _3.8 .

The gas generating container 10 charged with MnF _3.8 thus treated was heated to 400 ° C. to produce fluorine gas. When the obtained fluorine gas was analyzed, HF was 70 ppm by volume, CF ₄ was 30 ppm by volume, and SiF ₄ was below the detection limit (3 ppm by volume).

  Table 1 shows the impurity gas content of the fluorine gas and the steps carried out in the examples and comparative examples.

  According to the present invention, a large amount of high-purity fluorine gas can be obtained without using an expensive and dangerous fluorine electrolytic layer or fluorine gas cylinder, and the present invention can be industrially used in various fields. In particular, the fluorine gas obtained by the present invention is a high-purity fluorine gas that can be applied to the manufacture of semiconductors, and the present invention can supply such a high-purity fluorine gas safely and in large quantities. Also, in the fluorination of inorganic compounds and organic compounds, the use of high-purity fluorine gas does not produce impurities due to side reactions, and a higher quality product can be produced.

FIG. 1 is a schematic view of an example of a fluorine gas production apparatus used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container source valve 2 Pressure gauge 3 Stop valve 4 Stop valve 5 Mass flow controller 6 Cushion tank 7 NaF filling tower 8 Stop valve 9 Heater 10 Gas generating container 11 Vacuum pump 12 Detoxification cylinder

Claims (13)

Manganese fluoride,
(1) A step of reducing pressure while heating to 250 to 340 ° C.,
(2) releasing fluorine gas while heating to 340 to 500 ° C. under reduced pressure;
(3) Treating by fluorine gas while heating at 340 to 500 ° C., and (4) Treating by a method including a step of absorbing fluorine gas, heating the obtained manganese fluoride A method for producing high-purity fluorine gas, characterized by generating high-purity fluorine gas. The method for producing high-purity fluorine gas according to claim 1, wherein the manganese fluoride is represented by an average composition formula MnF _x (3 <x ≦ 4).   The method for producing high-purity fluorine gas according to claim 1 or 2, wherein in the step (1), the pressure is reduced to 0.005 MPa or less in absolute pressure.   In the said process (2), it is pressure-reduced to 0.005 Mpa or less with an absolute pressure, The manufacturing method of the high purity fluorine gas in any one of Claims 1-3 characterized by the above-mentioned.   The high purity fluorine gas according to any one of claims 1 to 4, wherein in the step (3), the pressure when contacting with the fluorine gas is 0.1 MPa or more and 1.0 MPa or less in absolute pressure. Production method.   The method for producing high-purity fluorine gas according to any one of claims 1 to 5, wherein the step (3) is repeated twice or more.   The fluorine fluoride is absorbed in the manganese fluoride after being used in the production method according to any one of claims 1 to 6, and the obtained manganese fluoride is heated to generate high-purity fluorine gas. A method for producing high-purity fluorine gas. (1) A step of reducing pressure while heating to 250 to 340 ° C.,
(2) releasing fluorine gas while heating to 340 to 500 ° C. under reduced pressure;
(3) containing manganese fluoride treated by a method comprising a step of reducing pressure after contacting with fluorine gas while heating to 340 to 500 ° C., and (4) a step of absorbing fluorine gas Purity fluorine gas production equipment. The high-purity fluorine gas production apparatus according to claim 8, wherein the manganese fluoride is represented by an average composition formula MnF _x (3 <x ≦ 4).   The high-purity fluorine gas production apparatus according to claim 8 or 9, wherein in the step (1), the pressure is reduced to 0.005 MPa or less in absolute pressure.   The high-purity fluorine gas production apparatus according to any one of claims 8 to 10, wherein in the step (2), the pressure is reduced to 0.005 MPa or less in absolute pressure. The high purity fluorine gas production according to any one of claims 8 to 11, wherein in the step (3), the pressure when contacting with the fluorine gas is 0.1 MPa or more and 1.0 MPa or less in absolute pressure. apparatus.   The said process (3) is repeated twice or more, The high purity fluorine gas manufacturing apparatus in any one of Claims 8-12 characterized by the above-mentioned.

Images