Gas-filled filling container and method for storing hydrogen halides

Abstract

Provided is a gas-filled filling container that is not prone to corrosion by hydrogen halides that contain water. This gas-filled filling container is realized by filling a filling container with hydrogen halides that contain water. The filling container is provided with a compressed gas cylinder in which the hydrogen halides are accommodated and a valve made of austenitic stainless steel. The austenitic stainless steel contains more than 0% by mass and no more than 0.03% by mass of carbon, more than 0% by mass and no more than 1.0% by mass of silicon, more than 0% by mass and no more than 1.5% by mass of manganese, at least 30.0% by mass and no more than 45.0% by mass of nickel, at least 16.0% by mass and no more than 25.0% by mass of chrome, at least 2.0% by mass and no more than 8.0% by mass of molybdenum, no more than 0.0050% by mass of sulfur, no more than 0.030% by mass of phosphorus, no more than 0.0050% by mass of oxygen, no more than 0.020% by mass of nitrogen, no more than 0.020% by mass of titanium, and no more than 0.020% by mass of aluminum, the remainder comprising iron and unavoidable impurities.

Description

Gas-filled filling container and method for storing hydrogen halide

[0001] The present disclosure relates to a gas-filled filling container and a method for storing hydrogen halide.

[0002] In order to perform fine processing stably in dry etching, the dry etching gas is required to be of high purity (for example, 99.9% by volume or more). Further, since the dry etching gas is stored in a filling container until use in a filled state, it is necessary to maintain high purity over a long period in the filling container. Hydrogen halide, which is used as a dry etching gas for semiconductor manufacturing, has a property of being easily soluble in water, and an aqueous solution of hydrogen halide becomes a hydrohalic acid and dissolves various metals. That is, it is considered that the cause of the deterioration of the purity of hydrogen halide is trace amounts of water in the filling container or trace amounts of water in hydrogen halide. Hydrogen halide containing water promotes corrosion of the inner surface of the filling container, and thus it is considered that the purity of hydrogen halide enclosed in the filling container deteriorates, but it is extremely difficult to completely remove water from the filling container and hydrogen halide.

[0003] Under such circumstances, at present, it is required that hydrogen halide has extremely few impurities, and particularly strict restrictions are imposed on the amount of metal impurities in the order of volume ppm. Manganese steel or the like used as a material for general filling containers corrodes due to the above reasons, and thus is not suitable as a material for a filling container for handling hydrogen halide for semiconductor manufacturing. Further, when hydrogen halide is stored in a filling container for a long period or used intermittently, the amount of metal impurities in the hydrogen halide gas tends to increase, and it is difficult to suppress the amount of metal impurities in the hydrogen halide gas to several volume ppm or less. Therefore, as a material for a filling container for hydrogen halide gas and members constituting a system for supplying hydrogen halide gas, it is preferable to use austenitic stainless steel typified by SUS316L in order to suppress deterioration of the purity of hydrogen halide due to corrosion.

[0004] Japanese Patent Publication No. 60307 of 1996

[0005] For example, Patent Document 1 discloses an austenitic stainless steel that is resistant to corrosion by hydrogen halides. However, if the hydrogen halide contains water, corrosion may occur even in austenitic stainless steel. In particular, the valve of the filling container may come into contact with the atmosphere, making it more susceptible to corrosion by hydrogen halides than other parts. As a result, the purity of the hydrogen halide sealed in the filling container may decrease during storage. This disclosure aims to provide a gas-filled container that is resistant to corrosion by hydrogen halides containing water, and a method for storing hydrogen halides.

[0006] To solve the aforementioned problems, one aspect of the present disclosure is as follows: [1] to [7] [1] A gas-filled container in which hydrogen halogen is filled, wherein the hydrogen halogen contains water, the container comprises a cylinder containing the hydrogen halogen and a valve that opens and closes a flow path for the hydrogen halogen inside the cylinder to flow to the outside, and the material of at least a portion of the valve that comes into contact with the hydrogen halogen is austenitic stainless steel. The austenitic stainless steel is a gas-filled container containing carbon in an amount exceeding 0% by mass and up to 0.03% by mass, silicon in an amount exceeding 0% by mass and up to 1.0% by mass, manganese in an amount exceeding 0% by mass and up to 1.5% by mass, nickel in an amount of 30.0% by mass or more and up to 45.0% by mass, chromium in an amount of 16.0% by mass or more and up to 25.0% by mass, molybdenum in an amount of 2.0% by mass or more and up to 8.0% by mass, sulfur in an amount of 0.0050% by mass or less, phosphorus in an amount of 0.030% by mass or less, oxygen in an amount of 0.0050% by mass or less, nitrogen in an amount of 0.020% by mass or less, titanium in an amount of 0.020% by mass or less, and aluminum in an amount of 0.020% by mass or less, with the remainder being iron and unavoidable impurities.

[0007] [2] The gas-filled container according to [1], wherein the water content of the hydrogen halide is 10 ppb or more and 10 ppm or less by volume. [3] The austenitic stainless steel further contains at least one of niobium, vanadium, zirconium, yttrium, copper in an amount exceeding 0% by mass and up to 0.90% by mass, tungsten in an amount exceeding 0% by mass and up to 2.00% by mass, tantalum in an amount exceeding 0% by mass and up to 0.50% by mass, calcium in an amount exceeding 0% by mass and up to 0.0010% by mass, magnesium in an amount exceeding 0% by mass and up to 0.0010% by mass, and boron in an amount of 0.0005% by mass or more and up to 0.010% by mass, wherein the total content of niobium and vanadium when at least one of niobium and vanadium is included is 0.001% by mass or more and up to 0.050% by mass, and the total content of zirconium and yttrium when at least one of zirconium and yttrium is included is 0% by mass and up to 0.0060% by mass, according to [1] or [2].

[0008] [4] A gas-filled container according to any one of [1] to [3], wherein the purity of the hydrogen halide is 99.99% by volume or more. [5] A gas-filled container according to any one of [1] to [4], wherein the hydrogen halide is at least one of hydrogen fluoride, hydrogen chloride, and hydrogen bromide.

[0009] [6] A method for storing hydrogen halogens, comprising filling a container with hydrogen halogens and storing the hydrogen halogens, wherein the hydrogen halogens contain water, the container comprises a cylinder containing the hydrogen halogens, and a valve for opening and closing a flow path for the hydrogen halogens inside the cylinder to flow to the outside, and at least a portion of the valve that comes into contact with the hydrogen halogens is made of austenitic stainless steel. A method for storing hydrogen halides, wherein the austenitic stainless steel contains carbon in an amount of more than 0% by mass and less than or equal to 0.03% by mass, silicon in an amount of more than 0% by mass and less than or equal to 1.0% by mass, manganese in an amount of more than 0% by mass and less than or equal to 1.5% by mass, nickel in an amount of more than 30.0% by mass and less than or equal to 45.0% by mass, chromium in an amount of more than 16.0% by mass and less than or equal to 25.0% by mass, molybdenum in an amount of more than 2.0% by mass and less than or equal to 8.0% by mass, sulfur in an amount of less than or equal to 0.0050% by mass, phosphorus in an amount of less than or equal to 0.030% by mass, oxygen in an amount of less than or equal to 0.0050% by mass, nitrogen in an amount of less than or equal to 0.020% by mass, titanium in an amount of less than or equal to 0.020% by mass, and aluminum in an amount of less than or equal to 0.020% by mass, with the remainder being iron and unavoidable impurities. [7] The method for storing hydrogen halides according to [6], wherein the water content of the hydrogen halide is 10 ppb by volume or more and 10 ppm by volume or less.

[0010] The gas-filled container and hydrogen halide storage method described herein are less prone to corrosion of the container due to hydrogen halide containing water.

[0011] This diagram illustrates an example of the configuration of an apparatus for evaluating the performance of test pieces in the examples and comparative examples.

[0012] One embodiment of the present disclosure is described below. This embodiment is merely an example of the present disclosure, and the disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and such modified or improved forms may also be included in the present disclosure.

[0013] The gas-filled container according to this embodiment is a gas-filled container in which hydrogen halogen is filled, the hydrogen halogen contains water, and the container comprises a cylinder containing the hydrogen halogen and a valve that opens and closes a flow path for the hydrogen halogen inside the cylinder to flow to the outside, wherein at least a portion of the valve that comes into contact with the hydrogen halogen is made of austenitic stainless steel, and the austenitic stainless steel contains carbon exceeding 0% by mass and 0.03% by mass or less, and carbon exceeding 0% by mass and 1% by mass It contains 0% by mass or less of silicon, more than 0% by mass and 1.5% by mass or less of manganese, 30.0% by mass or more and 45.0% by mass or less of nickel, 16.0% by mass or more and 25.0% by mass or less of chromium, 2.0% by mass or more and 8.0% by mass or less of molybdenum, 0.0050% by mass or less of sulfur, 0.030% by mass or less of phosphorus, 0.0050% by mass or less of oxygen, 0.020% by mass or less of nitrogen, 0.020% by mass or less of titanium, and 0.020% by mass or less of aluminum, with the remainder being iron and unavoidable impurities.

[0014] Furthermore, the hydrogen halide storage method according to this embodiment is a method for storing hydrogen halide by filling a filled container with hydrogen halide, wherein the hydrogen halide contains water, and the filled container comprises a cylinder containing the hydrogen halide and a valve that opens and closes a flow path for the hydrogen halide inside the cylinder to flow to the outside, wherein at least a portion of the valve that comes into contact with the hydrogen halide is made of austenitic stainless steel, and the austenitic stainless steel contains more than 0% by mass and 0.03% by mass or less of carbon, 0% by mass. It contains silicon in an amount exceeding 1.0% by mass or less, manganese in an amount exceeding 0% by mass or less than 1.5% by mass, nickel in an amount between 30.0% by mass and 45.0% by mass, chromium in an amount between 16.0% by mass and 25.0% by mass, molybdenum in an amount between 2.0% by mass and 8.0% by mass, sulfur in an amount of 0.0050% by mass or less, phosphorus in an amount of 0.030% by mass or less, oxygen in an amount of 0.0050% by mass or less, nitrogen in an amount of 0.020% by mass or less, titanium in an amount of 0.020% by mass or less, and aluminum in an amount of 0.020% by mass or less, with the remainder being iron and unavoidable impurities.

[0015] The cylinder of the filling container comes into contact with hydrogen halide, which has a low water (H2O) content, so corrosion is relatively unlikely to occur. However, the valve of the filling container may come into contact with the atmosphere, so even if the water content of the hydrogen halide is low, corrosion due to contact with the hydrogen halide is likely to occur. In the gas-filled container and the hydrogen halide storage method according to this embodiment, at least a portion of the valve of the filling container that comes into contact with the hydrogen halide is made of austenitic stainless steel with the alloy composition described above. Therefore, corrosion of the filling container is unlikely to occur even when in contact with hydrogen halide containing water (especially corrosion of the valve is unlikely to occur). As a result, according to the gas-filled container or the hydrogen halide storage method according to this embodiment, even if the gas-filled container is stored for a long period of time, the purity of the hydrogen halide it contains is unlikely to decrease. Therefore, if the gas-filled container is filled with high-purity hydrogen halide, the high purity is likely to be maintained even after long-term storage. In the austenitic stainless steel according to this embodiment, the mass loss rate before and after exposure to hydrogen bromide in Example 1, described later, may be 5.0% by mass or less, 4.0% by mass or less, or 3.0% by mass or less.

[0016] The alloy components and alloy composition of the austenitic stainless steel described above are explained in detail below. [Carbon: greater than 0% by mass and less than or equal to 0.03% by mass] Carbon (C) is an element that stabilizes the austenite phase. Carbon also contributes to solid solution strengthening and has the effect of increasing alloy strength. Furthermore, if the carbon content is 0.03% by mass or less, even if chromium carbides precipitate due to improper heat treatment, the austenitic stainless steel will be less susceptible to corrosion and the decrease in toughness of the austenitic stainless steel will be suppressed. The lower limit of the carbon content is preferably 0.005% by mass or more, and the upper limit is preferably 0.015% by mass or less, but the carbon content is preferably between 0.005% by mass and 0.015% by mass.

[0017] [Silicon: Over 0% by mass and 1.0% by mass or less] Silicon (Si) contributes to deoxidation and is effective in reducing oxide inclusions in austenitic stainless steel. Furthermore, if the silicon content is 1.0% by mass or less, the hot workability and toughness of the austenitic stainless steel are good. Preferably, the silicon content is over 0% by mass and 0.5% by mass or less.

[0018] [Manganese: Over 0% by mass and 1.5% by mass or less] Manganese (Mn) contributes to deoxidation and is effective in reducing oxide inclusions in austenitic stainless steel. Furthermore, if the manganese content is 1.5% by mass or less, sulfide formation is less likely to occur, and corrosion of austenitic stainless steel is less likely to occur. Preferably, the manganese content is over 0% by mass and 1.0% by mass or less.

[0019] [Nickel: 30.0% by mass or more and 45.0% by mass or less] Nickel (Ni) is an element that stabilizes the austenite phase and is indispensable for obtaining a single austenite phase. Nickel is also an important element in making austenitic stainless steel resistant to corrosion. If the nickel content is 45.0% by mass or less, the cost and workability of the austenitic stainless steel are good. The lower limit of the nickel content is preferably 33.0% by mass or more, and more preferably 36.0% by mass or more. The upper limit of the nickel content is preferably 40.0% by mass or less. In other words, the nickel content may be 33.0% by mass or more and 45.0% by mass or less, 33.0% by mass or more and 40.0% by mass or less, 36.0% by mass or more and 45.0% by mass or less, or 36.0% by mass or more and 40.0% by mass or less.

[0020] [Chromium: 16.0% by mass or more and 25.0% by mass or less] Chromium (Cr) is an important element in making austenitic stainless steel resistant to corrosion. In order to make austenitic stainless steel resistant to corrosion in environments where halogen elements are present, the lower limit of the chromium content is preferably 18.0% by mass or more, and more preferably 20.0% by mass or more.

[0021] Furthermore, if the chromium content is 25.0% by mass or less, intermetallic compounds are less likely to precipitate, resulting in good workability of the austenitic stainless steel. The upper limit of the chromium content is preferably 24.0% by mass or less, and more preferably 23.0% by mass or less. That is, the chromium content may be 16.0% by mass or more and 24.0% by mass or less, 16.0% by mass or more and 24.0% by mass or less, 16.0% by mass or more and 23.0% by mass or less, 18.0% by mass or more and 25.0% by mass or less, 18.0% by mass or more and 24.0% by mass or less, 18.0% by mass or more and 23.0% by mass or less, 20.0% by mass or more and 25.0% by mass or less, 20.0% by mass or more and 24.0% by mass or less, and 20.0% by mass or more and 23.0% by mass or less.

[0022] [Molybdenum: 2.0% by mass or more and 8.0% by mass or less] Molybdenum (Mo) is an important element in making austenitic stainless steel resistant to corrosion. In order to make austenitic stainless steel resistant to corrosion in environments in which halogen elements are present, the lower limit of the molybdenum content is preferably 3.0% by mass or more, more preferably 3.5% by mass or more, and even more preferably 4.0% by mass or more.

[0023] Furthermore, if the molybdenum content is 8.0% by mass or less, intermetallic compounds are less likely to precipitate, resulting in good hot workability of the austenitic stainless steel. The upper limit of the molybdenum content is preferably 7.0% by mass or less, and more preferably 6.0% by mass or less. In other words, the molybdenum content may be 2.0% by mass or more and 7.0% by mass or less, 2.0% by mass or more and 6.0% by mass or less, 3.0% by mass or more and 8.0% by mass or less, 3.5% by mass or more and 8.0% by mass or less, 4.0% by mass or more and 8.0% by mass or less, 2.0% by mass or more and 7.0% by mass or less, 3.0% by mass or more and 7.0% by mass or less, 3.5% by mass or more and 7.0% by mass or less, 4.0% by mass or more and 7.0% by mass or less, 2.0% by mass or more and 6.0% by mass or less, 3.0% by mass or more and 6.0% by mass or less, 3.5% by mass or more and 6.0% by mass or less, or 4.0% by mass or more and 6.0% by mass or less.

[0024] [Sulfur: 0.0050 mass% or less] Since sulfur (S) is an impurity element, it is desirable to keep the sulfur content low. If the sulfur content is 0.0050 mass% or less, the workability of the austenitic stainless steel will be good, and the austenitic stainless steel will be less susceptible to corrosion. The lower limit of the sulfur content may be greater than 0 mass%, but since sulfur is an impurity element, the sulfur content may be 0 mass%. In other words, the sulfur content may be 0 mass% or more and 0.0050 mass% or less, or greater than 0 mass% and 0.0050 mass% or less.

[0025] [Phosphorus: 0.030 mass% or less] Since phosphorus (P) is an impurity element, it is desirable to keep the phosphorus content low. If the phosphorus content is 0.030 mass% or less, the workability of austenitic stainless steel will be good. The lower limit of the phosphorus content may be greater than 0 mass%, but since phosphorus is an impurity element, the phosphorus content may be 0 mass%. In other words, the phosphorus content may be 0 mass% or more and 0.030 mass% or less, or greater than 0 mass% and 0.030 mass% or less.

[0026] [Oxygen: 0.0050 mass% or less] Since oxygen (O) is an impurity element, it is desirable to keep the oxygen content low. If the oxygen content is 0.0050 mass% or less, there are fewer oxide inclusions and the cleanliness of the austenitic stainless steel is high, resulting in good hot workability and toughness of the austenitic stainless steel. The lower limit of the oxygen content may be greater than 0 mass%, but since oxygen is an impurity element, the oxygen content may be 0 mass%. In other words, the oxygen content may be 0 mass% or more and 0.0050 mass% or less, or greater than 0 mass% and 0.0050 mass% or less.

[0027] [Nitrogen: 0.020 mass% or less] Nitrogen (N) contributes to solid solution strengthening and has the effect of increasing alloy strength. Furthermore, if the nitrogen content is 0.020 mass% or less, even if chromium nitride precipitates due to improper heat treatment, the austenitic stainless steel will be less susceptible to corrosion, and the decrease in the toughness of the austenitic stainless steel will be suppressed. The lower limit of the nitrogen content may be greater than 0 mass%, but since nitrogen is an impurity element, the nitrogen content may be 0 mass%. In other words, the nitrogen content may be 0 mass% or more and 0.020 mass% or less, or greater than 0 mass% and 0.020 mass% or less.

[0028] [Titanium: 0.020 mass% or less] Titanium (Ti) is a strong carbide-forming element that prevents the precipitation of chromium carbides, making austenitic stainless steel less susceptible to corrosion, and also suppresses the reduction in the toughness of austenitic stainless steel. Furthermore, if the titanium content is 0.020 mass% or less, the formation of coarse carbides is suppressed, resulting in good hot workability and toughness of austenitic stainless steel. The lower limit of the titanium content may be greater than 0 mass%, but since titanium is an impurity element, the titanium content may be 0 mass%. In other words, the titanium content may be 0 mass% or more and 0.020 mass% or less, or greater than 0 mass% and 0.020 mass% or less.

[0029] [Aluminum: 0.020 mass% or less] Aluminum (Al) contributes to deoxidation and is effective in reducing oxide inclusions in austenitic stainless steel. Furthermore, if the aluminum content is 0.020 mass% or less, the formation of coarse oxides is suppressed, resulting in good hot workability and toughness of the austenitic stainless steel. The lower limit of the aluminum content may be greater than 0 mass%, but since aluminum is an impurity element, the aluminum content may be 0 mass%. In other words, the aluminum content may be 0 mass% or more and 0.020 mass% or less, or greater than 0 mass% and 0.020 mass% or less.

[0030] The austenitic stainless steel in the gas-filled container and the austenitic stainless steel in the hydrogen halide storage method according to this embodiment preferably further contains at least one of niobium, vanadium, zirconium, yttrium, copper in an amount exceeding 0% by mass and up to 0.90% by mass, tungsten in an amount exceeding 0% by mass and up to 2.00% by mass, tantalum in an amount exceeding 0% by mass and up to 0.50% by mass, calcium in an amount exceeding 0% by mass and up to 0.0010% by mass, magnesium in an amount exceeding 0% by mass and up to 0.0010% by mass, and boron in an amount of 0.0005% by mass or more and up to 0.010% by mass, wherein the total content of niobium and vanadium when at least one of niobium and vanadium is included is 0.001% by mass or more and up to 0.050% by mass, and the total content of zirconium and yttrium when at least one of zirconium and yttrium is included is preferably exceeding 0% by mass and up to 0.0060% by mass.

[0031] [Niobium, Vanadium: Total 0.001% by mass or more, 0.050% by mass or less] Niobium (Nb) and vanadium (V) are strong carbide-forming elements that stabilize carbon, suppress the precipitation of chromium carbides, make austenitic stainless steel less susceptible to corrosion, and suppress the decrease in toughness of austenitic stainless steel.

[0032] To obtain this effect, it is preferable to include at least one of niobium and vanadium in the austenitic stainless steel, and the total content of niobium and vanadium in this case may be 0.001% by mass or more. Furthermore, if the total content of niobium and vanadium is 0.050% by mass or less, the formation of coarse carbides is suppressed, resulting in good hot workability and toughness of the austenitic stainless steel.

[0033] [Zirconium, Yttrium: Total exceeding 0% by mass and 0.0060% by mass or less] Zirconium (Zr) and yttrium (Y) have the effect of improving the hot workability of austenitic stainless steel. To obtain this effect, it is preferable to include at least one of zirconium and yttrium in the austenitic stainless steel, and in that case, the total content of zirconium and yttrium may be greater than 0% by mass and 0.0060% by mass or less.

[0034] [Copper: Over 0% by mass and 0.90% by mass or less] [Tungsten: Over 0% by mass and 2.00% by mass or less] [Tantalum: Over 0% by mass and 0.50% by mass or less] Copper (Cu), tungsten (W), and tantalum (Ta) have the effect of making austenitic stainless steel less susceptible to corrosion. Therefore, at least one of copper, tungsten, and tantalum may be included in austenitic stainless steel. If the copper content is 0.90% by mass or less, the tungsten content is 2.00% by mass or less, and the tantalum content is 0.50% by mass or less, the hot workability and cost of the austenitic stainless steel are good.

[0035] [Calcium: greater than 0% by mass and less than or equal to 0.0010% by mass] [Magnesium: greater than 0% by mass and less than or equal to 0.0010% by mass] Calcium (Ca) and magnesium (Mg) form sulfides and stabilize sulfur, thereby making austenitic stainless steel less susceptible to corrosion and improving its hot workability. When the calcium content is 0.0010% by mass or less and the magnesium content is 0.0010% by mass or less, sulfur concentration at grain boundaries is less likely to occur, resulting in good hot workability, such as hot forgeability, of austenitic stainless steel.

[0036] [Boron: 0.0005% by mass or more, or 0.010% by mass or less] Boron (B) segregates at grain boundaries, strengthening them and contributing to improved workability and mechanical strength of austenitic stainless steel. Furthermore, if the boron content is 0.010% by mass or less, excessive segregation at grain boundaries is less likely to occur, resulting in good workability such as ductility of austenitic stainless steel.

[0037] The austenitic stainless steel according to this embodiment can be obtained by melting and refining the raw materials necessary to obtain a predetermined alloy composition in, for example, an arc furnace, induction furnace, or vacuum induction furnace. Refining can be carried out using methods such as AOD (Argon-Oxygen-Decarburization) or VOD (Vacuum-Oxygen-Decarburization). The obtained ingot can be remelted one or more times by electroslag remelting (ESR) or vacuum arc remelting (VAR). This improves the cleanliness. Afterward, the molten metal is poured into a mold and solidified to form a steel ingot. Then, after being held in a predetermined temperature range for a predetermined time, the material for hot working according to this embodiment can be manufactured by hot forging or hot rolling.

[0038] [Filled Container] The filled container in the gas-filled filled container according to this embodiment, and the filled container in the hydrogen halogen storage method according to this embodiment, comprises a cylinder and a valve. The cylinder is a component that contains hydrogen halogen. Preferably, this cylinder is a seamless, integrally molded container. The valve is a component that opens and closes a flow path that allows hydrogen halogen inside the cylinder to flow to the outside, and controls the flow of hydrogen halogen through the flow path.

[0039] In the gas-filled container and the hydrogen halide storage method according to this embodiment, at least a portion of the valve that comes into contact with the hydrogen halide is made of austenitic stainless steel, but the material of the cylinder is not particularly limited. The material of the cylinder may be the same austenitic stainless steel as the valve, or it may be made of another material.

[0040] [Hydrogen Halide] In the gas-filled container and the hydrogen halide storage method according to this embodiment, the type of hydrogen halide is not particularly limited, but for example, the hydrogen halide may be at least one of hydrogen fluoride (HF), hydrogen chloride (HCl), and hydrogen bromide (HBr).

[0041] In the gas-filled container and the hydrogen halide storage method according to this embodiment, the purity of the hydrogen halide to be filled into the container (purity before filling into the container) is preferably 99.90% by volume or higher, more preferably 99.95% by volume or higher, and even more preferably 99.99% by volume or higher.

[0042] When dry etching is performed using hydrogen halide with a purity of 99.90% by volume or higher as the dry etching gas, the reproducibility of plasma behavior and etching performance tends to be good. There are no particular limitations on the method for measuring the purity of hydrogen halide, but for example, it can be measured by gas chromatography or Fourier transform infrared spectroscopy (FT-IR analysis).

[0043] Further, in the gas-filled container according to the present embodiment and the method for storing hydrogen halide according to the present embodiment, the water content of hydrogen halide is preferably 10 volume ppb or more and 10 volume ppm or less, more preferably 5 volume ppb or more and 5 volume ppm or less, and still more preferably 1 volume ppb or more and 1 volume ppm or less. If a hydrogen halide having a low water content as described above is filled into the filling container, the filling container including the valve and the cylinder is less likely to be corroded by the hydrogen halide, so that the purity of the hydrogen halide is less likely to decrease and high purity is likely to be maintained even after long-term storage.

[0044] The lower limit value of the water content of hydrogen halide is preferably 10 volume ppb or more, more preferably 5 volume ppb or more, and still more preferably 1 volume ppb or more. Further, the upper limit value of the water content of hydrogen halide is preferably 10 volume ppm or less, more preferably 5 volume ppm or less, and still more preferably 1 volume ppm or less.

[0045] The method for filling hydrogen halide into the filling container is not particularly limited. For example, there is a method of filling hydrogen halide through a filling line purged with an inert gas into a filling container whose inside is evacuated to a reduced pressure state. Examples of the inert gas include nitrogen gas (N2), argon (Ar), and helium (He).

[0046] The type of the purge treatment is not particularly limited, and a batch purge treatment in which the filling line is filled with an inert gas and then evacuated, or a flow purge treatment in which an inert gas is continuously flowed through the filling line can be used. The type of the filling line is not particularly limited, and a pipe whose inner surface is treated by passivation or electrolytic polishing may be used.

[0047] Examples and comparative examples are shown below to explain the present disclosure more specifically. First, while referring to FIG. 1, the configuration of an apparatus for evaluating the performance (corrosion resistance) of test pieces in the examples and comparative examples will be described. The apparatus of FIG. 1 includes a gas cylinder 1 filled with hydrogen halide gas, a mass flow controller 2 for controlling the flow rate of hydrogen halide gas, a liquid 4 for adjusting the humidity of the mixed gas of hydrogen halide and water, a reaction chamber 3 for reacting hydrogen halide with the liquid 4, and a pressure gauge 5 for measuring the pressure inside the reaction chamber 3.

[0048] In addition, the apparatus of FIG. 1 includes, on the downstream side of the reaction chamber 3, a reaction chamber 6 for exposing the test piece 10 to hydrogen halide, a pressure gauge 7 for measuring the pressure inside the reaction chamber 6, a thermometer 8 for measuring the temperature inside the reaction chamber 6, and a heating device 9 for heating the mixed gas and the test piece 10 inside the reaction chamber 6.

[0049] Furthermore, the apparatus of FIG. 1 includes, on the downstream side of the reaction chamber 6, a moisture meter 11 for measuring the humidity of the mixed gas, a decontamination device 12 for removing harmful substances from the mixed gas before exhausting the mixed gas to the outside, and a vacuum pump 13 for reducing the pressure inside the system. And these are connected to each other by piping as shown in FIG. 1.

[0050] When evaluating the corrosion resistance of the test piece 10 using the apparatus of FIG. 1, first, after installing the test piece 10 inside the reaction chamber 6, the hydrogen halide gas inside the gas cylinder 1 is sent to the reaction chamber 3 by the mass flow controller 2. The reaction chamber 3 contains water or hydrohalic acid as the liquid 4 for adjusting the humidity, and the humidity of the mixed gas supplied into the reaction chamber 6 can be arbitrarily controlled by bubbling the liquid 4 using the hydrogen halide gas whose flow rate is adjusted by the mass flow controller 2. When not passing through the reaction chamber 3, hydrogen halide gas with a humidity of 0% can be supplied into the reaction chamber 6.

[0051] The reaction chambers 3 and 6 are not particularly limited as long as they are made of a material resistant to hydrogen halide gas and hydrohalogen acids, but examples of materials include fluororesins (e.g., PFA, PTFE, PVDF, PCTFE). Similarly, the piping connected to the reaction chambers 3 and 6 is not particularly limited as long as it is made of a material resistant to hydrogen halide gas and hydrohalogen acids, but it is preferable that it has a structure that can withstand a predetermined pressure.

[0052] In the exposure step in which the test piece 10 is exposed to hydrogen halide, the temperature at which the test piece 10 reacts with the mixed gas can be determined by arbitrarily controlling the temperature inside the reaction chamber 6 using the heating device 9. The temperature at which the test piece 10 reacts with the mixed gas in the exposure step is not particularly limited, but considering the temperature in the actual operating environment, it is preferably 0°C to 80°C, more preferably 10°C to 70°C, and even more preferably 20°C to 60°C.

[0053] The pressure during the exposure process can be determined by arbitrarily controlling the pressure inside the reaction chamber 6 using the mass flow controller 2 and a valve attached to the reaction chamber 6. The pressure during the exposure process is not particularly limited, but considering the pressure in actual operating environments, it is preferably 1 Pa or more and 5 MPa or less, more preferably 10 Pa or more and 4 MPa or less, and even more preferably 100 Pa or more and 3 MPa or less.

[0054] The humidity of the mixed gas in the exposure process can be determined by arbitrarily controlling the humidity of the mixed gas in the reaction chamber 6 using the mass flow controller 2 and the moisture content meter 11. The humidity of the mixed gas in the exposure process is not particularly limited, but considering the humidity in the actual operating environment, it is preferable to have a humidity of 2500 ppm by volume or more in a humid environment.

[0055] While there are no particular limitations on the exposure time in the exposure process, it is preferable to have an exposure time of one week or more, considering the actual operating environment. The exposure time refers to the time from when the mixed gas is supplied to the reaction chamber 6 containing the test piece 10 until the mixed gas is exhausted to end the exposure. After the exposure is complete, the mixed gas is exhausted from the reaction chamber 6 to the outside, but it is sent to a detoxification device 12 to remove harmful substances before being exhausted to the outside.

[0056] [Preparation of Test Pieces] Raw materials, formulated to have the specified components shown in Tables 1 and 2, were first melted in a vacuum induction heating furnace, and then secondly melted in a vacuum arc remelting furnace. The cast steel after the second melting was hot forged and hot rolled to obtain steel with a thickness of 10 mm, and then the steel plate, which was solution treated at 1200°C, was processed to a size of 15 mm in length, 15 mm in width, and 1 mm in thickness to be used as test pieces.

[0057] [Example 1] A metal test piece 10 for evaluating corrosion resistance was placed in a reaction chamber 6 (a PFA multi-purpose pressure-resistant jar manufactured by Savillex Co., Ltd.) equipped with a pressure gauge 7 and a thermometer 8. The shape of the test piece 10 was a plate with dimensions of 15 mm in length, 15 mm in width, and 1 mm in thickness. The type of metal forming the test piece 10 was austenitic stainless steel, and its alloy composition is as shown in Table 1.

[0058] Furthermore, 50 mL of pure water was placed in reaction chamber 3 (a PFA multi-purpose pressure-resistant jar manufactured by Savillex) as liquid 4 to adjust the humidity of the mixed gas of hydrogen halide and water. The reaction chamber 6 was heated using an oil bath, which is a heating device 9. The heating of reaction chamber 6 was continued until the reading on the thermometer 8 reached 40°C.

[0059] When the reading on thermometer 8 reached 40°C, hydrogen bromide (manufactured by Resonaq Corporation, purity 99.99% by volume or higher), with a flow rate of 500 mL / min adjusted using mass flow controller 2 (digital mass flow controller SEC-N100 manufactured by Horiba STEC Co., Ltd.), was supplied to reaction chamber 3.

[0060] After closing the valve on the downstream side of reaction chamber 3 to seal it, hydrogen bromide was supplied to reaction chamber 3 from gas cylinder 1, and the pure water in reaction chamber 3 was bubbled with hydrogen bromide. Hydrogen bromide was then continuously supplied to reaction chamber 3 until the pressure inside reaction chamber 3 reached 1 MPa. After supplying hydrogen bromide to the above pressure value, the valve on the downstream side of reaction chamber 3 was opened, and a mixed gas of water and hydrogen bromide was supplied from reaction chamber 3 to reaction chamber 6. The humidity of the mixed gas supplied to reaction chamber 6 was measured using a moisture content meter 11 (Techne Measuring Instruments Co., Ltd., Corrosive Gas Continuous Moisture Analyzer TMA-210), and it was confirmed that the water content of the mixed gas was 2500 ppm by volume or more.

[0061] The mixed gas was continuously supplied to the reaction chamber 6 for one hour. When water droplets began to precipitate inside the reaction chamber 6, the valve on the downstream side of the reaction chamber 6 was closed to seal the chamber 6, and the mixed gas was continued to be supplied to the reaction chamber 6 until the pressure inside the chamber 6 reached 1 MPa. After supplying the mixed gas to the above pressure, the valve on the upstream side of the reaction chamber 6 was closed to seal the chamber 6, and the temperature inside the reaction chamber 6 was maintained at 40°C while the test piece 10 was continuously exposed to the mixed gas for one week.

[0062] After the above exposure time had elapsed, the valve on the upstream side of reaction chamber 6 was opened, and the mixed gas inside reaction chamber 6 was absorbed by a filtration device (Clean S ZH acid gas filtration device, manufactured by Resonaq Corporation). Reaction chamber 6 was opened, and the test piece 10 was recovered, and the mass of the test piece 10 was measured. The amount of mass loss and the mass loss rate from the mass before exposure were then calculated. The results are shown in Table 1.

[0063]

[0064] [Comparative Examples 1-8] The test pieces 10 were exposed to the mixed gas and evaluated in the same manner as in Example 1, except that the type of metal forming the test piece 10 was different. The results are shown in Table 1. The alloy compositions of the metals forming the test pieces 10 used in Comparative Examples 1, 2, 4-8 are as shown in Table 1. The metal forming the test piece 10 used in Comparative Example 3 is nickel, as shown in Table 1.

[0065] As can be seen from the results of Example 1 and Comparative Examples 1 to 8, the austenitic stainless steel in the gas-filled container according to this embodiment, and the austenitic stainless steel in the hydrogen halide storage method according to this embodiment, were less susceptible to corrosion by hydrogen halides even in a humid environment where the moisture content in the mixed gas was 2500 volume ppm or more.

[0066] [Example 2] Two test pieces 10 of the same type as those used in Example 1 were prepared. The two test pieces 10 were placed inside a 10L capacity filling container. The two test pieces 10 were suspended in the space inside the filling container using a string and rod made of fluororesin. One test piece 10 was placed 20 cm above the bottom of the filling container, and the other test piece 10 was placed 60 cm above the bottom of the filling container.

[0067] After attaching a valve to the filling container, 10 kg of hydrogen bromide (manufactured by Resonaq Co., Ltd., purity 99.99% by volume or higher) was supplied into the filling container through the valve, and the valve was closed to seal the filling container. At this time, one test piece 10 was immersed in the liquid phase of hydrogen bromide, and the other test piece 10 was placed in the gas phase of hydrogen bromide. The water content of the hydrogen bromide was 2 ppm by volume.

[0068] Test piece 10 was continuously exposed to hydrogen bromide for one month at room temperature. After the above exposure time had elapsed, hydrogen bromide gas was discharged from the filled container. The valve was removed from the filled container and test piece 10 was recovered, and its mass was measured. The amount of mass loss and the mass loss rate from the mass before exposure were then calculated. The results are shown in Table 2.

[0069] [Example 3] In Example 3, the same procedure as in Example 2 was followed, except that hydrogen bromide was replaced with hydrogen fluoride (manufactured by Resonaq Corporation, purity 99.999% by volume or higher). The test piece 10 was exposed to hydrogen halides and evaluated. However, in Example 3, only the test piece 10 immersed in the liquid phase of hydrogen fluoride was evaluated. The results are shown in Table 2. The water content of the hydrogen fluoride is 1 ppm by volume.

[0070]

[0071] As can be seen from the results of Example 2, the austenitic stainless steel in the gas-filled container according to this embodiment, and the austenitic stainless steel in the hydrogen halide storage method according to this embodiment, were less susceptible to corrosion by hydrogen halides even in a dry environment where the hydrogen bromide water content was 2 ppm by volume.

[0072] As can be seen from the results of Example 3, the austenitic stainless steel in the gas-filled container according to this embodiment, and the austenitic stainless steel in the hydrogen halide storage method according to this embodiment, were less susceptible to corrosion by hydrogen halides even in a dry environment where the water content of hydrogen fluoride was 1 ppm by volume.

Claims

1. A gas-filled container in which hydrogen halogen is filled, wherein the hydrogen halogen contains water, and the container comprises a cylinder containing the hydrogen halogen and a valve that opens and closes a flow path for the hydrogen halogen inside the cylinder to flow to the outside, wherein at least a portion of the valve that comes into contact with the hydrogen halogen is made of austenitic stainless steel. The austenitic stainless steel is a gas-filled container containing carbon in an amount exceeding 0% by mass and up to 0.03% by mass, silicon in an amount exceeding 0% by mass and up to 1.0% by mass, manganese in an amount exceeding 0% by mass and up to 1.5% by mass, nickel in an amount of 30.0% by mass or more and up to 45.0% by mass, chromium in an amount of 16.0% by mass or more and up to 25.0% by mass, molybdenum in an amount of 2.0% by mass or more and up to 8.0% by mass, sulfur in an amount of 0.0050% by mass or less, phosphorus in an amount of 0.030% by mass or less, oxygen in an amount of 0.0050% by mass or less, nitrogen in an amount of 0.020% by mass or less, titanium in an amount of 0.020% by mass or less, and aluminum in an amount of 0.020% by mass or less, with the remainder being iron and unavoidable impurities.

2. The gas-filled container according to claim 1, wherein the water content of the hydrogen halide is 10 ppb or more and 10 ppm or less by volume.

3. The gas-filled container according to claim 1 or claim 2, wherein the austenitic stainless steel further contains at least one of niobium, vanadium, zirconium, yttrium, copper in an amount exceeding 0% by mass and up to 0.90% by mass, tungsten in an amount exceeding 0% by mass and up to 2.00% by mass, tantalum in an amount exceeding 0% by mass and up to 0.50% by mass, calcium in an amount exceeding 0% by mass and up to 0.0010% by mass, magnesium in an amount exceeding 0% by mass and up to 0.0010% by mass, and boron in an amount of 0.0005% by mass or more and up to 0.010% by mass, wherein when at least one of niobium and vanadium is included, the total content of niobium and vanadium is 0.001% by mass or more and up to 0.050% by mass, and when at least one of zirconium and yttrium is included, the total content of zirconium and yttrium is 0% by mass and up to 0.0060% by mass.

4. The gas-filled container according to claim 1 or claim 2, wherein the purity of the hydrogen halide is 99.99% by volume or more.

5. The gas-filled container according to claim 1 or claim 2, wherein the hydrogen halide is at least one of hydrogen fluoride, hydrogen chloride, and hydrogen bromide.

6. A method for storing hydrogen halogens, comprising filling a container with hydrogen halogens, wherein the hydrogen halogens contain water, the container comprises a cylinder containing the hydrogen halogens, and a valve for opening and closing a flow path that allows the hydrogen halogens inside the cylinder to flow to the outside, and at least a portion of the valve that comes into contact with the hydrogen halogens is made of austenitic stainless steel. A method for storing hydrogen halides, wherein the austenitic stainless steel contains carbon in an amount exceeding 0% by mass and up to 0.03% by mass, silicon in an amount exceeding 0% by mass and up to 1.0% by mass, manganese in an amount exceeding 0% by mass and up to 1.5% by mass, nickel in an amount of 30.0% by mass or more and up to 45.0% by mass, chromium in an amount of 16.0% by mass or more and up to 25.0% by mass, molybdenum in an amount of 2.0% by mass or more and up to 8.0% by mass, sulfur in an amount of 0.0050% by mass or less, phosphorus in an amount of 0.030% by mass or less, oxygen in an amount of 0.0050% by mass or less, nitrogen in an amount of 0.020% by mass or less, titanium in an amount of 0.020% by mass or less, and aluminum in an amount of 0.020% by mass or less, with the remainder being iron and unavoidable impurities.

7. The method for storing hydrogen halogen according to claim 6, wherein the water content of the hydrogen halogen is 10 ppb or more and 10 ppm or less by volume.

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