Method for producing acid fluoride-filled container

Abstract

Provided is a method for producing an acid fluoride-filled container, in which the purity of an acid fluoride filled therein is less likely to decrease. This method for producing an acid fluoride-filled container is for producing an acid fluoride-filled container comprising a container and an acid fluoride therein. In the container, at least the inner surface is formed of a metal material, and the inner surface has a surface roughness Rz of 0.01-10 μm. The method includes: a treatment step for introducing a treatment gas, which contains an acid fluoride for treatment use for treating the inner surface of the container, into the container so as to bring the acid fluoride for treatment use into contact with the inner surface at a temperature of 160°C or lower; an extraction step for extracting the treatment gas, which has been introduced into the container in the treatment step, from the container; and a filling step for filling the container, which has undergone the extraction step, with an acid fluoride to be stored in the container.

Description

Method for manufacturing acid fluoride-filled containers

[0001] The present disclosure relates to a method for producing a pre-filled container of an acid fluoride.

[0002] Metallic containers are often used as containers for storing acid fluorides. However, when acid fluorides are stored in metallic containers, the acid fluorides may react with the metal material or carbon forming the inner surface of the metallic container, or with water adhering to the inner surface of the metallic container. As a result, gas impurities such as carbon monoxide (CO), carbon dioxide (CO), carbon tetrafluoride (CF), and hydrogen fluoride (HF) as well as metal impurities are generated, which may cause a problem of gradual deterioration in the purity of the acid fluorides stored in the metallic container.

[0003] Japanese Patent Publication No. 2009-57248

[0004] An object of the present disclosure is to provide a method for producing a container filled with acid fluoride that is less likely to cause a decrease in the purity of the acid fluoride filled therein.

[0005] In order to solve the above problems, one aspect of the present disclosure is as follows: [1] to [6]: [1] A method for producing an acid fluoride-filled container in which an acid fluoride is filled in a container, wherein at least the inner surface of the container is formed of a metal material and the surface roughness Rz of the inner surface is 0.01 μm or more and 10 μm or less, the method comprising: a treatment step of introducing a treatment gas containing a treatment acid fluoride for treating the inner surface into the container and bringing the treatment acid fluoride into contact with the inner surface at a temperature of 160° C. or less, an extraction step of extracting the treatment gas introduced into the container in the treatment step from the container, and a filling step of filling the container after the extraction step with acid fluoride to be stored in the container.

[0006] [2] The method for producing an acid fluoride-filled container according to [1], wherein the metal material forming the inner surface has an iron content of 60 mass% or more and a chromium content of 10 mass% or less. [3] The method for producing an acid fluoride-filled container according to [1], wherein the metal material forming the inner surface is at least one of manganese steel and chromium-molybdenum steel. [4] The method for producing an acid fluoride-filled container according to any one of [1] to [3], wherein the contents of carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride in the acid fluoride extracted from the container after the filling step are all 10 volume ppm or less.

[0007] [5] The method for producing an acid fluoride-filled container according to any one of [1] to [4], wherein the acid fluoride to be filled into the container in the filling step is at least one of carbonyl fluoride, oxalyl fluoride, and trifluoromethylacetyl fluoride.

[0008] According to the method for producing a container filled with acid fluoride according to the present disclosure, it is possible to produce a container filled with acid fluoride in which the purity of the filled acid fluoride is less likely to decrease.

[0009] 1 is a schematic diagram of an acid fluoride filling apparatus illustrating a method for manufacturing an acid fluoride-filled container according to one embodiment of the present disclosure. FIG.

[0010] An embodiment of the present disclosure will be described below. Note that this embodiment shows an example of the present disclosure, and the present disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and embodiments incorporating such modifications or improvements can also be included in the present disclosure. Note that in this specification, pressure is expressed as gauge pressure unless otherwise specified.

[0011] The method for producing an acid fluoride-filled container according to this embodiment is a method for producing an acid fluoride-filled container in which an acid fluoride is filled in a container, wherein at least the inner surface of the container is formed of a metal material and the surface roughness Rz of the inner surface is 0.01 μm or more and 10 μm or less, and the method comprises a treatment step of introducing a treatment gas containing a treatment acid fluoride for treating the inner surface into the container and bringing the treatment acid fluoride into contact with the inner surface at a temperature of 160° C. or less; an extraction step of extracting the treatment gas introduced into the container in the treatment step from the container; and a filling step of filling the container after the extraction step with acid fluoride to be stored in the container.

[0012] The acid fluoride-filled container manufactured by the method for manufacturing an acid fluoride-filled container according to the present embodiment is less likely to suffer from a decrease in the purity of the filled acid fluoride. Therefore, the acid fluoride-filled container manufactured by the method for manufacturing an acid fluoride-filled container according to the present embodiment and the acid fluoride filled in the acid fluoride-filled container can be used as an electronic material gas for semiconductor manufacturing or as a raw material for precision organic synthesis.

[0013] [Acid Fluoride Filling Apparatus] An example of the configuration of an acid fluoride filling apparatus that can be used in the method for producing an acid fluoride-filled container according to this embodiment will be described with reference to Fig. 1. The acid fluoride filling apparatus in Fig. 1 includes a raw material tank 1 that contains acid fluoride, a cylinder 2 that is a container for storing the acid fluoride, a pipe 3 that connects the raw material tank 1 and the cylinder 2, and a valve 4 that is provided on the pipe 3. At least the inner surface of the cylinder 2 is made of a metal material (for example, a cylinder made of a metal material), and the surface roughness Rz of the inner surface is 0.01 µm or more and 10 µm or less.

[0014] A branch pipe 5 extends from the pipe 3 downstream of the valve 4, and is connected to a vacuum pump 7, with the exhaust port of the vacuum pump 7 connected to a detoxification device (not shown). A valve 6 is provided on the branch pipe 5 upstream of the vacuum pump 7. Furthermore, the cylinder 2 is equipped with a temperature regulator 8, which allows the temperature of the cylinder 2 to be set to any desired value.

[0015] By using the acid fluoride charging apparatus having such a configuration, the method for producing an acid fluoride-filled container according to this embodiment can be carried out to produce an acid fluoride-filled container. Specifically, acid fluoride contained in raw material tank 1 is introduced into cylinder 2 via pipe 3, and the acid fluoride is brought into contact with the inner surface of cylinder 2 at any temperature below 160°C (treatment step). Then, the acid fluoride is discharged from cylinder 2 via branch pipe 5 using vacuum pump 7 (extraction step). Then, the acid fluoride contained in raw material tank 1 is introduced back into cylinder 2 via pipe 3 (filling step), thereby producing an acid fluoride-filled container filled with acid fluoride containing few impurities.

[0016] The acid fluoride charging apparatus may include devices not shown in Fig. 1. For example, it may include a regulator for charging the acid fluoride contained in the raw material tank 1 into the cylinder 2 at a desired pressure, and a mass flow controller for controlling the flow rate of the acid fluoride when the acid fluoride contained in the raw material tank 1 is sent to the cylinder 2.

[0017] [Acid Fluoride] An acid fluoride is a compound having a functional group *-C(=O)F in the molecule. Here, "*" means any atom or atomic group. The number of carbon atoms in the acid fluoride is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less.

[0018] Examples of acid fluorides include carbonyl fluoride (COF), oxalyl fluoride (COF), trifluoromethylacetyl fluoride (CFCHCOF), formyl fluoride, carbonyl chloride fluoride, acetyl fluoride, 2,2,3,3,3-pentafluoropropanoyl fluoride, 2,2,3,3,4,4,4-heptafluorobutanoyl fluoride, 2,2,3,3,4,4,5,5,5-nonafluoropentanoyl fluoride, 2,2,3,4,4,4-hexafluoro-3-(trifluoromethyl)butanoyl fluoride, and 3,3,3-trifluoro-2,2-bis(trifluoromethyl)propanoyl fluoride.

[0019] Among these acid fluorides, from the viewpoint of easy availability, carbonyl fluoride, oxalyl fluoride, and trifluoromethylacetyl fluoride are preferred, and carbonyl fluoride is more preferred. The acid fluorides may be used alone or in combination of two or more. That is, the acid fluoride filled into the container in the filling step may be at least one of carbonyl fluoride, oxalyl fluoride, and trifluoromethylacetyl fluoride.

[0020] The acid fluoride filled into the container in the filling step is preferably of high purity, but since excessive purification leads to an increase in the manufacturing cost of the acid fluoride-filled container, it may contain a small amount of impurities.For example, the purity of the acid fluoride filled into the container in the filling step is preferably 95% by volume or more and 100% by volume or less, more preferably 98% by volume or more and 99.99999% by volume or less, and even more preferably 99% by volume or more and 99.9999% by volume or less.If the purity of the acid fluoride filled into the container in the filling step is within the above numerical range, the acid fluoride filled into the acid fluoride-filled container is unlikely to be mixed with gas impurities and metal impurities, and therefore the purity is unlikely to decrease.

[0021] [Impurities] In the present disclosure, the term "impurities" refers to components other than those intentionally mixed into the acid fluoride filled in the acid fluoride-filled container. Examples of impurities that may be contained in the acid fluoride filled in the acid fluoride-filled container include gas impurities such as nitrogen gas (N), hydrogen gas (H), carbon dioxide (CO), oxygen gas (O), argon (Ar), water (HO), hydrogen fluoride (HF), carbon monoxide (CO), and carbon tetrafluoride (CF), as well as metal impurities.

[0022] Among the gas impurities, carbon monoxide, carbon dioxide, hydrogen fluoride, and carbon tetrafluoride may be generated during storage if the inner surface of the container filled with acid fluoride is made of a metal material. The content of any type of gas impurity contained in the acid fluoride filled in the container filled with acid fluoride is preferably 5% by volume or less, more preferably 1% by volume or less, even more preferably 300 ppm by volume or less, even more preferably 100 ppm by volume or less, even more preferably 10 ppm by volume or less, and particularly preferably 5 ppm by volume or less. For example, it is preferable that the contents of carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride in the acid fluoride extracted from the container after the filling step are all 10 ppm by volume or less.

[0023] Furthermore, when an acid fluoride containing a metal is used for etching, the chamber may be contaminated with the metal, which may cause abnormal discharge, resulting in non-uniform plasma and metal contamination of the object to be etched. Therefore, it is preferable to remove as much metal as possible by purification.

[0024] Examples of the metal include metal elements from the third to sixth periods of the periodic table, such as Na, Mg, Al, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, Mo, and W. These metals may be contained in the acid fluoride as simple substances and / or as metal compounds. Note that the metal compound refers to a compound containing a metal element and a non-metal element, and examples include metal oxides, metal nitrides, metal oxynitrides, metal chlorides, metal bromides, metal iodides, and metal sulfides.

[0025] Among the above metals, Na, Cr, Mn, Fe, Co, Ni, Cu, and Mo are often contained in the containers and metal pipes in which acid fluorides are filled, and therefore are likely to be mixed into acid fluorides. Cr, in particular, is likely to be mixed into acid fluorides because it reacts with acid fluorides to form volatile metal complexes (CrO2F2, CrF6, etc.).

[0026] The metal content in the acid fluoride can be quantified, for example, by a technique such as inductively coupled plasma mass spectrometry (ICP-MS). The metal content of the acid fluoride filled in the acid fluoride-filled container is preferably 0.1 mass ppb to 300 mass ppb inclusive, more preferably 0.5 mass ppb to 100 mass ppb inclusive, and even more preferably 1 mass ppb to 20 mass ppb inclusive. For example, it is preferable that the metal content of each metal contained in the liquid phase of the acid fluoride extracted from the container after the filling step is less than 100 mass ppb.

[0027] [Material of container] The container for filling with acid fluoride to produce an acid fluoride-filled container has at least the inner surface formed of a metal material, and the material is not particularly limited as long as the surface roughness Rz of the inner surface is 0.01 μm or more and 10 μm or less, but a metal container formed entirely of a metal material is preferred.

[0028] The type of metallic material is not particularly limited, but a metallic material having an iron content of 60% by mass or more and a chromium content of 10% by mass or less is preferred. That is, the iron content of the metallic material forming the inner surface of the container is preferably 60% by mass or more and a chromium content of 10% by mass or less. Furthermore, the type of metallic material is not particularly limited, but manganese steel, chromium-molybdenum steel, stainless steel, etc. are preferred. That is, the metallic material forming the inner surface of the container is preferably at least one of manganese steel and chromium-molybdenum steel.

[0029] Manganese steel preferably contains 97% by mass or more of iron and 1% by mass or more and 2% by mass or less of manganese. When carbon and chromium are contained in the manganese steel, the carbon content is preferably 0.5% by mass or less, and the chromium content is preferably 0.35% by mass or less. Examples of manganese steel include SMn420, SMn433, SMn438, SMn443, STH11, and STH12. Chromium-molybdenum steel preferably contains 95% by mass or more of iron and 0.9% by mass or more and 1.5% by mass or less of chromium. When carbon is contained in the chromium-molybdenum steel, the carbon content is preferably 0.5% by mass or less. Examples of chromium-molybdenum steel include STH21 and STH22.

[0030] The stainless steel may contain 70% by mass or more of iron and 10.5% by mass or more of chromium. When acid fluoride is filled into a stainless steel container, chromium reacts with the acid fluoride to form a volatile metal complex, as described above, and chromium is easily contained in the acid fluoride gas. Therefore, the chromium content in the stainless steel is usually preferably less than 5% by mass. However, if an acid fluoride-filled container is produced using the method disclosed herein, the incorporation of chromium into the acid fluoride is suppressed even when the acid fluoride is filled into a stainless steel container. If carbon is contained in the stainless steel, the carbon content is preferably 1.5% by mass or less. Examples of stainless steel include SUS304, SUS316, and SUS316L.

[0031] [Surface roughness Rz of the inner surface of the container] The surface roughness Rz of the inner surface of the container to be filled with acid fluoride to produce an acid fluoride-filled container is preferably 0.01 μm or more and 10 μm or less, more preferably 0.05 μm or more and 5 μm or less, and particularly preferably 0.1 μm or more and 2 μm or less. The surface roughness Rz means the maximum height roughness defined in JIS B0601:2001.

[0032] When the surface roughness Rz of the inner surface of the container is small, the gas adsorption performance of the inner surface of the container is reduced. Therefore, the amount of water adsorbed and remaining on the inner surface of the container is reduced, and the water content of the acid fluoride is likely to be low. In addition, the amounts of carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride produced by the reaction of acid fluoride with water are reduced, and the purity of the acid fluoride filled in the container is unlikely to decrease. In addition, when the surface roughness Rz of the inner surface of the container is small, the contact area with the acid fluoride is reduced, and therefore the reaction between the metal material and the acid fluoride is unlikely to occur, and the metal is unlikely to be released into the acid fluoride.

[0033] Therefore, by reducing the surface roughness Rz of the inner surface of the container, the amount of water adsorbed on the inner surface of the container is reduced, and the reaction between the metal material and the acid fluoride is suppressed, so that the purity of the acid fluoride filled in the container is less likely to decrease. The surface roughness Rz of the inner surface of the container can be adjusted, for example, by polishing. The polishing method is not particularly limited, but for example, electrolytic polishing, buffing, barrel polishing, etc. can be used.

[0034] [Treatment Step] The method for producing a container filled with acid fluoride according to this embodiment includes a treatment step of introducing a treatment gas containing a treatment acid fluoride for treating the inner surface of the container into the container and bringing the treatment acid fluoride into contact with the inner surface of the container at a temperature of 160°C or less.

[0035] In the treatment step, the water adsorbed on the inner surface of the vessel is reacted with the treatment acid fluoride, and the impurities such as chromium and carbon on the inner surface of the vessel are also reacted with the treatment acid fluoride to produce carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride, and these impurities are volatilized.

[0036] The processing gas may be a gas consisting of only the processing acid fluoride, or may be a mixed gas of the processing acid fluoride and other gases. Examples of other gases include inert gases such as nitrogen gas and argon. The processing acid fluoride used in the processing step and the acid fluoride stored in the container in the filling step may be the same type of acid fluoride or different types of acid fluorides.

[0037] If the temperature in the treatment step is 160°C or lower, the generation of carbon monoxide and fluorine gas (F2) due to the decomposition of the treating acid fluoride is unlikely to occur. However, if the temperature in the treatment step is too low, the reaction between the treating acid fluoride and impurities will be difficult to proceed, so the temperature in the treatment step is preferably −78°C or higher and 160°C or lower, more preferably −30°C or higher and 100°C or lower, even more preferably 10°C or higher and 80°C or lower, and particularly preferably higher than 40°C and 75°C or lower.

[0038] The pressure of the treatment step is not particularly limited and can be appropriately set within the range of, for example, 10 kPa to 15 MPa. The treatment step may be carried out in a state in which the treating acid fluoride is vaporized in the container, but it is desirable to carry out the treatment step at a pressure at which the treating acid fluoride is liquefied in the container or at its critical pressure. Specifically, the pressure in the container is preferably 0.3 MPa to 10 MPa, more preferably 1 MPa to 9 MPa, even more preferably 1.5 MPa to 8 MPa, and particularly preferably 6 MPa to 7.6 MPa. The phase change state of the treating acid fluoride in the container can be controlled by the temperature and pressure of the treatment step and the amount of treating acid fluoride filled.

[0039] The time for which the treatment step is carried out is not particularly limited as long as it is possible to ensure that the time required for the treating acid fluoride to sufficiently react with the impurities in the container is secured, and may be, for example, 20 seconds to 300 hours. In consideration of the reproducibility and productivity of the treatment step, the treatment step is preferably carried out for 1 minute to 200 hours, more preferably 5 minutes to 100 hours, even more preferably 10 minutes to 48 hours, and particularly preferably 15 minutes to 24 hours. If the time required for the treatment step is within the above range, the impurities in the container can be sufficiently reacted with the treating acid fluoride.

[0040] The treatment step may be carried out with the container standing still, or may be carried out while moving the container using a cylinder rotator or a shaker. When the treatment step is carried out while moving the container, convection of the treating acid fluoride occurs within the container, thereby increasing the efficiency of the reaction between the treating acid fluoride and the impurities. The treatment step may be carried out only once, or may be carried out repeatedly multiple times. When the treatment step is carried out repeatedly multiple times, the treatment step is followed by a withdrawal step (described later) before the next treatment step is carried out.

[0041] [Extraction Step] The method for manufacturing a container filled with acid fluoride according to this embodiment includes an extraction step of extracting the processing gas introduced into the container in the processing step from the container. In the extraction step, the entire amount of processing gas introduced into the container may be extracted, or a portion of the processing gas introduced into the container may be extracted. When a portion of the processing gas introduced into the container is extracted, the amount of processing gas to be extracted may be determined so that the amount of impurities contained in the processing gas remaining in the container is reduced to a reference value or less.

[0042] From the viewpoint of reducing the amount of processing gas used, it is preferable to extract a small amount of processing gas from the vessel. For example, the amount of processing gas extracted may be 0.1% by mass or more and 100% by mass or less of the amount of processing gas introduced into the vessel in the processing step, but is preferably 3% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 80% by mass or less.

[0043] [Filling Step] The method for producing a container filled with acid fluoride according to this embodiment includes a filling step of filling the container after the extracting step with acid fluoride for storage in the container. The amount of acid fluoride to be filled in the filling step is not particularly limited as long as it is an amount that does not overfill the container. Overfilling refers to the container being completely filled with liquefied acid fluoride.

[0044] The temperature at which the filling step is carried out is not particularly limited, but is preferably higher than the temperature at which the acid fluoride solidifies. Furthermore, since carrying out the filling step at a temperature lower than the temperature of the treatment step tends to reduce the amount of impurities derived from the container, the temperature at which the filling step is carried out is preferably lower than the temperature of the treatment step. For example, the temperature at which the filling step is carried out is preferably −84° C. or higher and 120° C. or lower, more preferably −79° C. or higher and 80° C. or lower, even more preferably −20° C. or higher and 60° C. or lower, and particularly preferably 0° C. or higher and 30° C. or lower.

[0045] In the acid fluoride-filled container manufactured by the method for manufacturing an acid fluoride-filled container according to this embodiment, gas impurities and metal impurities are unlikely to be mixed into the filled acid fluoride, and therefore the purity of the filled acid fluoride is unlikely to decrease. The purity of the acid fluoride taken out from the acid fluoride-filled container manufactured by the method for manufacturing an acid fluoride-filled container according to this embodiment is preferably 99% by volume or more, and more preferably 99.9% by volume or more.

[0046] The method for measuring the purity of the acid fluoride is not particularly limited, but the purity can be determined by analyzing the contents of impurities such as carbon monoxide, carbon dioxide, carbon tetrafluoride, hydrogen fluoride, and metals in the acid fluoride using Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma mass spectrometry (ICP-MS), or the like.

[0047] The present disclosure will be described in more detail below with reference to examples and comparative examples. Example 1 A container filled with acid fluoride was produced using a charging device having a configuration substantially similar to that of the acid fluoride charging device shown in Figure 1 (see Table 1). The acid fluoride for treatment and the acid fluoride to be stored in the container were both carbonyl fluoride and contained in raw material tanks.

[0048] The gas impurities and metal impurities contained in this carbonyl fluoride are as follows: carbon monoxide 5 ppm by volume, carbon dioxide 6 ppm by volume, hydrogen fluoride 4 ppm by volume, carbon tetrafluoride 3 ppm by volume, sodium less than 5 ppb by mass, chromium less than 5 ppb by mass, manganese less than 5 ppb by mass, iron less than 5 ppb by mass, cobalt less than 5 ppb by mass, nickel less than 5 ppb by mass, copper less than 5 ppb by mass, and molybdenum less than 5 ppb by mass.

[0049] The container for filling the acid fluoride was a 10 L manganese steel (STH12) cylinder (manufactured by Asahi Seisakusho Co., Ltd.). The inner surface of this cylinder had a surface roughness Rz of 5 μm. Using a filling device, carbonyl fluoride was supplied from a raw material tank to the cylinder under conditions of 3 MPa and 50°C and sealed. After leaving it to stand for 2 hours after sealing (treatment step), the entire amount of carbonyl fluoride was extracted from the cylinder (extraction step).

[0050] Next, using a filling device, 5 kg of carbonyl fluoride was supplied from the raw material tank to the cylinder after the extraction step and sealed (filling step). The cylinder was then stored at a temperature of 30 to 35°C for 12 months. After 12 months of storage, a portion of the carbonyl fluoride was extracted from the cylinder. The concentrations of gas impurities (carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride) in the carbonyl fluoride were measured using a MAX-iR Fourier transform infrared spectrometer manufactured by Thermo Fisher Scientific. Furthermore, the concentrations of metal impurities (sodium, chromium, manganese, iron, cobalt, nickel, copper, and molybdenum) in the liquid phase of carbonyl fluoride were measured using an Element 2 inductively coupled plasma mass spectrometer manufactured by Thermo Fisher Scientific. The results are shown in Table 2.

[0051] The gas impurity measurement conditions are as follows. The gas impurities in carbonyl fluoride stored in the raw material tank were also measured under the same conditions. Measurement temperature: 27°C Measurement pressure: 101.3 to 102 kPa Cell length: 10 m Cell window plate: AgCl Measurement wavelength: Carbon monoxide 2172 cm -1Carbon dioxide 2360 cm -1 Hydrogen fluoride 4038 cm -1 Carbon tetrafluoride 1281 cm -1

[0052] The measurement conditions for metal impurities are as follows. Metal impurities in carbonyl fluoride stored in a raw material tank were also measured under the same conditions. First, the liquid phase of carbonyl fluoride was removed from the cylinder and vaporized, and the vaporized carbonyl fluoride was bubbled into 100 g of a nitric acid aqueous solution with a concentration of 1% by mass. In this way, a mixed solution of carbonyl fluoride and a nitric acid aqueous solution was prepared. Since the mass of the mixed solution was 200 g, it is considered that 100 g of carbonyl fluoride was mixed with 100 g of the nitric acid aqueous solution.

[0053] Next, 1 g of the mixture was sampled and analyzed for metals using a fusion coupled plasma mass spectrometer to measure the signal intensities (y) of sodium, chromium, manganese, iron, cobalt, nickel, copper, and molybdenum in the mixture. The concentrations of each metal were calculated from the signal intensities using a calibration curve.

[0054] The calibration curve was prepared as follows. That is, nitric acid standard solutions with metal concentrations of 0 mass ppb (no metal), 10 mass ppb, and 100 mass ppb were prepared, and analyzed using an inductively coupled plasma mass spectrometer. A calibration curve was then prepared with the metal concentration on the horizontal axis and the signal intensity on the vertical axis, and its slope (a) and intercept (b) were determined. The same procedure was performed for sodium, chromium, manganese, iron, cobalt, nickel, copper, and molybdenum, and a calibration curve for each metal was prepared. The concentration M of the metal contained in the mixed solution can be calculated using the following formula: M = (y - b) / a

[0055]

[0056]

[0057] Examples 2 to 14 and Comparative Examples 1, 2, and 4 Acid fluoride-filled containers were produced in the same manner as in Example 1, except that the material of the cylinder (container), the surface roughness Rz of the inner surface of the cylinder, the type of acid fluoride for treatment, the conditions of the treatment step (pressure, temperature, time), the conditions of the extraction step (amount extracted, number of times the extraction step was performed), the type of acid fluoride filled in the cylinder, and the conditions of the filling step (amount filled) were changed as shown in Table 1. The number of times the extraction step was performed means the number of times the cycle was repeated, where one cycle is defined as the treatment step and the extraction step being performed consecutively.

[0058] The concentrations of gaseous impurities and metal impurities in the acid fluoride were measured in the same manner as in Example 1. The results are shown in Table 2. The gaseous impurities and metal impurities contained in the oxalyl fluoride stored in the raw material tank were as follows: carbon monoxide 6 ppm by volume, carbon dioxide 3 ppm by volume, hydrogen fluoride 3 ppm by volume, carbon tetrafluoride 5 ppm by volume, sodium less than 5 ppb by mass, chromium less than 5 ppb by mass, manganese less than 5 ppb by mass, iron less than 5 ppb by mass, cobalt less than 5 ppb by mass, nickel less than 5 ppb by mass, copper less than 5 ppb by mass, and molybdenum less than 5 ppb by mass.

[0059] The gas impurities and metal impurities contained in the trifluoromethylacetyl fluoride stored in the raw material tank are as follows: carbon monoxide 3 ppm by volume, carbon dioxide 5 ppm by volume, hydrogen fluoride 4 ppm by volume, carbon tetrafluoride 3 ppm by volume, sodium less than 5 ppb by mass, chromium less than 5 ppb by mass, manganese less than 5 ppb by mass, iron less than 5 ppb by mass, cobalt less than 5 ppb by mass, nickel less than 5 ppb by mass, copper less than 5 ppb by mass, and molybdenum less than 5 ppb by mass.

[0060] Furthermore, the gas impurities and metal impurities contained in the iodine heptafluoride stored in the raw material tank are as follows: carbon monoxide 2 ppm by volume, carbon dioxide 2 ppm by volume, hydrogen fluoride 2 ppm by volume, carbon tetrafluoride less than 1 ppm by volume, sodium less than 5 ppb by mass, chromium less than 5 ppb by mass, manganese less than 5 ppb by mass, iron less than 5 ppb by mass, cobalt less than 5 ppb by mass, nickel less than 5 ppb by mass, copper less than 5 ppb by mass, and molybdenum less than 5 ppb by mass.

[0061] Comparative Example 3 An acid fluoride-filled container was produced in the same manner as in Example 1, except that the filling step was carried out without carrying out the treatment step and the extraction step. Then, the concentrations of gas impurities and metal impurities in the acid fluoride were measured in the same manner as in Example 1. The results are shown in Table 2.

[0062] The results of Examples 1 to 3 reveal the following. That is, when a container filled with acid fluoride was manufactured using carbonyl fluoride, oxalyl fluoride, or trifluoromethylacetyl fluoride as the acid fluoride in the treating step and the filling step, and manganese steel as the material for the container for filling with acid fluoride, the amounts of gas impurities and metal impurities did not increase even when the acid fluoride was stored in the container for a certain period of time. In particular, when oxalyl fluoride was used as the treating acid fluoride, a container filled with acid fluoride could be manufactured without any problems even when the pressure condition in the treating step was 0.15 MPa.

[0063] The results of Examples 4 to 6 reveal the following: Even when chromium-molybdenum steel was used as the material for the container for filling with acid fluoride, a container filled with acid fluoride could be produced without any problems. Furthermore, the amounts of gas impurities and metal impurities did not increase even after storing the acid fluoride in the container for a certain period of time.

[0064] The results of Examples 7 to 9 reveal the following. That is, even when the surface roughness Rz of the inner surface of the container was 10 μm or 2 μm, a container filled with acid fluoride could be produced without any problems. Furthermore, even when the acid fluoride was stored in the container for a certain period of time, the amount of gaseous impurities and metal impurities hardly increased. In particular, when the treatment step and extraction step were repeated three times and when the surface roughness Rz of the inner surface of the container was reduced (2 μm), the effect of suppressing the increase in the amount of gaseous impurities and metal impurities was high.

[0065] The results of Examples 10 and 11 reveal the following: Even when the temperature of the treatment process was set to 20° C. or 160° C., a container filled with acid fluoride could be produced without any problems. Furthermore, even when the acid fluoride was stored in the container for a certain period of time, the amounts of gas impurities and metal impurities did not increase significantly.

[0066] The results of Example 12 reveal the following: Even when only 10% of the carbonyl fluoride introduced into the vessel in the treatment step was extracted in the extraction step and then the filling step was carried out, a vessel filled with acid fluoride could be produced without any problems. Furthermore, even when the acid fluoride was stored in the vessel for a certain period of time, the amount of impurities did not increase significantly.

[0067] The results of Example 13 reveal the following: Even when the amount of acid fluoride filled into the container in the filling step was 1 kg, a container filled with acid fluoride could be produced without any problems. Furthermore, even when the acid fluoride was stored in the container for a certain period of time, the amounts of gas impurities and metal impurities did not increase.

[0068] The results of Example 14 reveal the following: Even when different types of acid fluoride were used in the treatment step and the filling step, a container filled with acid fluoride could be produced without any problems. Furthermore, even when the acid fluoride was stored in the container for a certain period of time, the amounts of gas impurities and metal impurities did not increase.

[0069] The results of Comparative Example 1 reveal the following: When iodine heptafluoride was used instead of acid fluoride, the amounts of gas impurities and metal impurities increased after storing iodine heptafluoride in the container for a certain period of time. In particular, the amounts of hydrogen fluoride and chromium increased significantly to 100 ppm by volume or more and 100 ppb by volume or more, suggesting that the present disclosure is an effective method for manufacturing a filled container for acid fluoride.

[0070] The results of Comparative Example 2 reveal the following. That is, even if the material of the container is manganese steel, if the surface roughness Rz of the inner surface of the container is large, the amounts of gas impurities and metal impurities increase after storing acid fluoride in the container for a certain period of time. This result suggests that the condition of the surface roughness Rz of the inner surface of the container is important.

[0071] The results of Comparative Example 3 reveal the following. That is, when acid fluoride was filled into a container that had not undergone the treatment step and the extraction step, the amounts of gas impurities and metal impurities increased after the acid fluoride was stored in the container for a certain period of time. This result suggests that the treatment step and the extraction step are essential. The results of Comparative Example 4 reveal the following. That is, when the temperature in the treatment step exceeded 160°C, the amounts of gas impurities and metal impurities increased after the acid fluoride was stored in the container for a certain period of time. This result suggests that the temperature conditions in the treatment step are important.

[0072] 1... Raw material tank 2... Cylinder 3... Piping 5... Branch piping

Claims

1. A method for producing an acid fluoride-filled container in which an acid fluoride is filled in a container, the method comprising: a treatment step of introducing a treatment gas containing a treatment acid fluoride for treating the inner surface into the container and bringing the treatment acid fluoride into contact with the inner surface at a temperature of 160°C or less; an extraction step of extracting the treatment gas introduced into the container in the treatment step from the container; and a filling step of filling the container after the extraction step with acid fluoride to be stored in the container.

2. A method for manufacturing an acid fluoride-filled container as described in claim 1, wherein the iron content of the metal material forming the inner surface is 60 mass % or more and the chromium content is 10 mass % or less.

3. The method of claim 1, wherein said metallic material forming said inner surface is at least one of manganese steel and chromium-molybdenum steel.

4. A method for producing an acid fluoride-filled container according to any one of claims 1 to 3, wherein the acid fluoride extracted from the container after the filling step has a content of carbon monoxide, carbon dioxide, carbon tetrafluoride, and hydrogen fluoride of 10 ppm by volume or less.

5. A method for producing a container filled with acid fluoride described in any one of claims 1 to 3, wherein the content of metals contained in the liquid phase of the acid fluoride extracted from the container after the filling step is less than 100 ppb by mass for each metal.

6. A method for producing an acid fluoride-filled container according to any one of claims 1 to 3, wherein the acid fluoride filled into the container in the filling step is at least one of carbonyl fluoride, oxalyl fluoride, and trifluoromethylacetyl fluoride.