TW202438718A - Liquefied gas container and method of manufacturing liquefied gas container - Google Patents

Abstract

The container (100) containing liquefied gas of the present invention is constructed as follows: it has a containing part (10) and liquefied gas (30) contained in the containing part (10), the containing part (10) has a metal film (20) on the inner surface (12), and has a fluoride passivation film (22) containing metal fluoride on the metal film (20), and the containing part (10) contains gas (35) and liquid (33), the gas (35) contains a gas phase (34) of the liquefied gas (30), and the liquid (33) contains a liquid phase (32) of the liquefied gas (30), as well as nickel element and/or copper element.

Description

Container containing liquefied gas and method for manufacturing container containing liquefied gas

The present invention relates to a container containing liquefied gas and a method for manufacturing the container containing liquefied gas.

Various developments have been conducted so far for containers containing liquefied gas. As such a technology, the technology described in Patent Document 1 is known. Patent Document 1 discloses that corrosion resistance to halogen gas is improved by forming a fluoride passivation film on the surface of a metal material (claim 1 of Patent Document 1, invention effect, etc.). Prior Art Documents Patent Documents

Patent document 1: Japanese Patent Publication No. 02-263972

[The problem the invention is trying to solve]

However, the results of the inventor's research show that the gas storage container using the metal material with a fluorinated passivation film described in the above-mentioned Patent Document 1 has room for improvement in suppressing the performance changes of the liquefied gas. [Technical means for solving the problem]

After further research, the inventors found that by using a container with a fluoride passivation film formed on a metal film and making the liquid in the container contain nickel and/or copper elements, the difference in gas composition between the initial liquefied gas before the container is opened and the liquefied gas after the gas begins to be released can be made extremely small. As a result, the change in gas performance can be suppressed, thereby completing the present invention.

According to one aspect of the present invention, the following container containing liquefied gas and a method for manufacturing the container containing liquefied gas are provided. 1. A container containing liquefied gas, comprising: a storage portion, and liquefied gas stored in the storage portion, wherein the storage portion has a metal film on the inner surface, and a fluoride passivation film containing metal fluoride on the metal film, the stored liquefied gas includes a liquid phase and a gas phase, and the liquid phase contains nickel and/or copper. 2. The container containing liquefied gas as described in 1., wherein the total content of the nickel and copper elements in the liquid phase measured by ICP emission spectrometry is not less than 10 wt ppb and not more than 1000 wt ppm. 3. The container containing liquefied gas as described in 1. or 2., wherein the liquefied gas is HF or ClF ₃ . 4. A container containing liquefied gas as described in any one of 1. to 3., wherein the amount of the main component in the gas phase of the liquefied gas is 99.9 volume % or more. 5. A container containing liquefied gas as described in any one of 1. to 4., wherein the amount of _F2 in the gas phase of the liquefied gas is less than 100 volume ppm. 6. A container containing liquefied gas as described in any one of 1. to 5., wherein the housing portion comprises one or more selected from the group consisting of stainless steel, carbon steel, manganese steel, nickel steel, and aluminum steel. 7. A container containing liquefied gas as described in any one of 1. to 6., wherein the metal film has a coating film. 8. A container for liquefied gas as described in any one of 1. to 7., wherein the metal film contains nickel and/or copper as a main component. 9. A container for liquefied gas as described in any one of 1. to 8., wherein the film thickness of the metal film is 1 μm to 300 μm. 10. A container for liquefied gas as described in any one of 1. to 9., wherein the fluoride passivation film is a room temperature fluoride passivation film. 11. A container for liquefied gas as described in any one of 1. to 10., wherein at least a portion of the fluoride passivation film has a dissolution mark. 12. A method for manufacturing a container containing liquefied gas, which comprises a housing portion and liquefied gas contained in the housing portion, the method comprising the following steps: forming a metal film on the inner surface of the housing portion; forming a passivation fluoride film containing metal fluoride on the metal film; and introducing the liquefied gas into the housing portion on which the passivation fluoride film is formed, thereby obtaining a container containing liquefied gas, wherein the container containing liquefied gas has liquid and gas in the housing portion, the gas containing a gas phase of the liquefied gas, and the liquid containing a liquid phase of the liquefied gas, as well as nickel and/or copper elements. 13. The method for manufacturing a container containing liquefied gas as described in 12., wherein the step of forming the above-mentioned fluorine passive film is the following step: allowing fluorine-containing gas to flow into the above-mentioned receiving portion at room temperature and contact the above-mentioned metal film. [Effect of the Invention]

According to the present invention, a container containing liquefied gas and a method for manufacturing the container containing liquefied gas which are excellent in suppressing the property variation of the liquefied gas are provided.

The following is an explanation of the embodiments of the present invention using drawings. In all drawings, the same components are labeled with the same symbols and the explanation is omitted as appropriate. In addition, the drawings are schematic and do not correspond to the actual size ratio.

The outline of the container containing liquefied gas according to this embodiment is described.

The container containing liquefied gas of the present embodiment has a storage part and liquefied gas stored in the storage part. The container containing liquefied gas of the present embodiment has the following structure: the storage part has a metal film on the inner surface, and a fluoride passivation film containing metal fluoride is provided on the metal film, and the storage part contains gas and liquid, the gas contains a gas phase of liquefied gas, and the liquid contains a liquid phase of liquefied gas, as well as nickel element and/or copper element.

Furthermore, the above-mentioned "on the inner surface" and "on the metal film" may mean direct contact with the inner surface and the metal film, or may mean that any film or layer is interposed between the inner surface and the metal film. The so-called "containing nickel and copper elements" means that the content in the liquid in the storage part is above the detection limit (1 weight ppb or more) when measured by ICP emission spectrometry. The nickel and copper elements contained in the liquid may be contained in the form of metal or metal ions, or may be contained in part or all of the form of metal fluoride or metal fluoride ions (hereinafter, the metal state and ion state are not distinguished, and are recorded as "metal" or "metal fluoride").

By using the container containing liquefied gas of the present embodiment, it is possible to suppress the degradation of the highly corrosive liquefied gas or the inadvertent mixing of impurities, etc., so that the difference in gas composition between the initial liquefied gas before the container is opened and the liquefied gas after the gas begins to be released can be made extremely small, thereby suppressing the change of gas properties such as etching energy. Generally speaking, the container containing liquefied gas is directly set in the gas supply part of various devices such as semiconductors, and its contents are taken out in the form of gas, but if the gas properties change, the various settings of the gas supply object must be adjusted accordingly according to the change. Furthermore, when the liquefied gas in the container is used up, a new container containing gas that has not been consumed will be replaced. However, if there is a difference in gas performance before and after the replacement, it will require the steps of re-adjusting various settings of the device to which the gas is supplied, thus making the operation complicated during the operation of mass production equipment.

According to the findings of the inventors, it has been discovered that by coating the inner surface of a container containing liquefied gas with a metal film and a fluoride passivation film and allowing the non-gas in the container (e.g., the liquid) to contain a specific metal element, the change in gas properties as described above can be suppressed.

Although the details of the mechanism are unclear, it is believed that by using a metal film and a fluoride passivation film, the corrosion of the storage part by the liquefied gas can be further suppressed compared to the case where each is used separately, so that impurities from the container can be suppressed from accidentally mixing into the liquid or gas in the container. Furthermore, it is believed that the fluorine mixed into the storage part by the metal/metal fluoride such as Ni or _NiF2 dissolved in the liquid in the container is captured (intercepted), so that further changes in the gas composition of the gas can be suppressed. Furthermore, it is speculated that one of the sources of the above-mentioned fluorine is a trace amount of residual fluorine adsorbed on the surface of the film when the above-mentioned fluoride passivation film is formed. Therefore, it is believed that changes in the gas properties of the liquefied gas can be suppressed.

In addition, since the vapor pressure of metals/metal fluorides such as Ni or _NiF2 in the liquid is relatively low, it is possible to suppress the mixing of these metals into the gas in the storage unit. As a result, the purity of the liquefied gas taken out from the container containing the liquefied gas is maintained for a long time.

Regarding the content of nickel or copper in the liquid in the storage unit, the total content of the nickel and copper in the liquid is preferably set to 10 wt ppb to 1000 wt ppm, more preferably 30 wt ppb to 800 wt ppm, and more preferably 50 wt ppb to 500 wt ppm. In addition, when only one of the nickel and copper elements is included, the content can be set to, for example, 10 wt ppb to 1000 wt ppm, preferably 30 wt ppb to 800 wt ppm, and more preferably 50 wt ppb to 500 wt ppm. By setting it within the above range, it is easy to suppress the change of the gas performance of the liquefied gas. In addition, the liquid may also contain other components as long as they are within the range that does not affect the change of the gas performance of the gas phase of the liquefied gas. For example, the components of the liquefied gas whose vapor pressure is lower than that of the contained gas can be listed, such as iron, cobalt, molybdenum, silver, etc. The content of nickel or copper can be measured by ICP emission spectrometry. The object of measurement is the liquefied gas just taken out from the container containing the liquefied gas (initial period).

The liquefied gas filled in the container containing the liquefied gas can be used for various purposes, for example, it can be preferably used as a semiconductor gas. Specifically, the liquefied gas can be a halogen-containing liquefied gas, preferably a fluorine-containing liquefied gas. Among the fluorine-containing liquefied gases, HF or ClF ₃ can be preferably used as an etching gas for miniaturization in the semiconductor field.

The following is a detailed description of the various components of the container containing liquefied gas according to this embodiment.

Fig. 1(a) is a cross-sectional view schematically showing the structure of a container 100 containing liquefied gas. Fig. 1(b) is an enlarged view of a region α of Fig. 1(a).

The container 100 containing liquefied gas includes a housing portion 10 filled with liquefied gas 30 .

The housing portion 10 contains a gas 35 and a liquid 33 . The gas 35 includes a gas phase 34 of a liquefied gas 30 . The liquid 33 includes a liquid phase 32 of a liquefied gas and a nickel element and/or a copper element.

If the gas 35 substantially only includes the gas phase 34 as described later, high-purity liquefied gas can be taken out from the gas container 100, which is preferred.

As described above, the liquid 33 may contain any compound or component other than the liquid phase 32 of the liquefied gas and the nickel element and/or the copper element, as long as it is within a range that does not adversely affect the gas 35 and the gas phase 34 of the liquefied gas. In addition, the liquid 33 may be substantially composed of only the liquid phase 32 and the nickel element and/or the copper element. For example, when all the liquids in the receiving portion 10 are set to 100% by weight, the liquid phase 32 may be set to 98% by weight or more, preferably 99% by weight or more, more preferably 99.5% by weight or more, and further preferably 99.9% by weight or more.

When the internal space of the receiving portion 10 is set to 100% by volume, the upper limit of the content of the liquid 33 can be set to, for example, 95% by volume or less, preferably 90% by volume or less, and more preferably 85% by volume or less. In addition, the content of the gas 35 in the receiving portion 10 can be set to, for example, 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. By setting the volume of the gas 35 in the receiving portion 10 to a specific value or more, even if impurities are mixed in the gas 35, the larger the volume, the more the impurities are diluted, and the lower the concentration of the impurities, so the influence on the gas performance can be suppressed. On the other hand, regarding the lower limit of the content of the liquid 35, it can be set to 50% by volume or more in the 100% by volume of the internal space of the container 10, for example, in the initial period, but it is not limited to this after the release of the liquefied gas 30 begins.

As the liquefied gas 30, those that are highly corrosive to metals can be cited, for example, fluorine-containing liquefied gases such as HF and ClF _3. Since it is easier to use when the contained liquefied gas 30 is one type of gas, the liquefied gas 30 is preferably HF or ClF _3. Even if it is a highly corrosive liquefied gas 30, the container 100 containing the liquefied gas can be stably stored.

The gas 35 in the housing 10 is preferably substantially composed of the gas phase 34 of the liquefied gas 30. For example, 99.9% by volume or more of the gas 35 in the housing 10 may be the gas phase 34 of the liquefied gas 30. More preferably, 99.95% by volume or more of the gas phase 34 of the liquefied gas 30 is more preferably the gas phase 34 of the liquefied gas 30, and even more preferably, 99.99% by volume or more of the gas phase 34 of the liquefied gas 30 is more preferably the gas phase 34 of the liquefied gas 30. In this way, the liquefied gas 30 can be used while maintaining a high purity.

It is preferred that the gas 35 in the housing 10 contain as little F ₂ as possible, for example, it can be set to less than 100 volume ppm, preferably less than 30 volume ppm, and more preferably less than 10 volume ppm. In this way, the liquefied gas 30 can be used with high purity.

In this specification, ICP emission spectrometry can be used to measure the types and amounts of components in the gas 35 in the container. The object of measurement is the gas 35 just taken out from the container 100 containing the liquefied gas (initial period).

The receiving portion 10 includes a container having an inner space surrounded by a wall portion.

The storage part 10 may include a corrosion-resistant metal material or a ceramic material. The storage part 10 may include one or more selected from the group consisting of stainless steel, carbon steel, manganese steel, nickel steel, and aluminum steel. In addition, nickel alloys such as monel alloy and Herschel alloy or materials obtained by grinding the above-mentioned various steels may be used. Among them, stainless steel (SUS) and manganese steel are preferred from the perspective of low price and excellent durability. The above-mentioned stainless steel can be used as a well-known container, for example, it can be an alloy steel of 50% by mass or more of iron and any component (chromium, nickel, etc.) for improving corrosion resistance. Furthermore, in addition to the corrosion-resistant metal material as the main component, the housing 10 may also contain metal elements such as nickel and chromium that are inevitably mixed in.

The housing portion 10 has a metal film 20 formed on the inner surface 12, and a fluoride passivation film 22 containing metal fluoride formed on the metal film 20. The metal film 20 and the fluoride passivation film 22 are configured to cover at least the inner surface 12 where the liquid 33 is present, but may also cover the entire surface of the inner surface 12. In addition, when the metal film 20 does not completely cover the inner surface 12, the uncoated surface of the metal film 20 is preferably a surface or film that is not easily corroded by the liquefied gas 30 and does not have an adverse effect on the gas phase 34 even if corroded. As the surface or film as described above, a well-known one can be used without particular limitation. As a film, for example, a gold-plated film or a fluororesin film can be listed.

The metal film 20 may be constituted to include nickel and/or copper as the main component. In addition to nickel and copper, any component constituting the metal film 20 may also be included. As the arbitrary component, it is more desirable to be one that is not easy to react with the liquefied gas 30, such as gold or fluororesin. Moreover, even if it is a component that may be partially mixed into the liquid 33 from the metal film 20, it may be included in the metal film 20, as long as the vapor pressure is low as described above and does not have an adverse effect on the gas phase 34. For example, iron, cobalt, molybdenum, silver, etc. may be listed. Moreover, of course, even if gold or fluororesin are not components of the metal film 20, they may be included in the metal film 20. In addition, for the purpose of improving the adhesion between the metal film 20 and the inner surface 12 and the durability of the metal film 20, an arbitrary coating layer may be provided between the metal film 20 and the inner surface 12. Furthermore, in this specification, the so-called main component refers to 80% by weight or more in terms of weight conversion. In the case where the above-mentioned metal film contains both nickel and copper, the so-called "containing nickel and copper as main components" means that the total content of the two in the metal film is 80% by weight or more.

The thickness of the metal film 20 is, for example, not less than 1 μm and not more than 300 μm, preferably not less than 2 μm and not more than 200 μm, and more preferably not less than 3 μm and not more than 100 μm.

The method for forming the metal film 20 is not limited. For example, the metal film 20 may be formed by sputtering or coating. In particular, coating is preferred because it is easy to form the film in accordance with the shape of the container. In addition, if a coating is used, the inner surface of the container housing 10 and the outer surface of the container can be made of different materials, and the desired container can be obtained at low cost. The coating can be formed by a known method, for example, electrolytic plating, electroless plating, melt plating, etc.

The housing portion 10 has an inlet and outlet mechanism for introducing the liquefied gas 30 into the interior of the space and/or releasing the gas 35 in the housing portion 10 to the outside. As an example of the inlet and outlet mechanism, the housing portion 10 has a take-out port 50 as shown in FIG. 1 and a filling port for the liquefied gas not shown (for example, a liquid-contacting member for filling). A valve 40 may also be provided at the take-out port 50. Furthermore, the take-out port 50 and the filling port may be the same. The valve 40, the take-out port 50, and the filling port may include corrosion-resistant metal materials or ceramic materials, etc., and may also include the same materials as the housing portion 10. Furthermore, the surfaces of the valve 40, the take-out port 50, and the filling port that are in contact with the liquefied gas 30 or the gas 35 in the housing portion may be formed with the above-mentioned metal film 20 or the fluoride passivation film 22.

The material of the outer surface of the container 100 containing liquefied gas, that is, the outer surface of the wall portion in contact with the outside atmosphere, is not particularly limited, and can be a corrosion-resistant metal material or a ceramic material like the housing portion 10. In addition, for the purpose of improving physical strength and chemical strength, an arbitrary coating can be provided on the surface. In addition, the outer surface can be made of the same material as the metal film 20, but from the perspective of low price and excellent durability, stainless steel (SUS) and manganese steel are preferred.

The fluoride passivation film 22 includes metal fluoride obtained by the reaction of the metal component contained in the metal film 20 with a fluorine-containing gas such as _F2 gas. Examples of the metal fluoride include _NiF2 , _CuF2 , etc., depending on the metal component contained in the metal film 20. Furthermore, in the case where the housing portion 10 is not covered with the fluoride passivation film 22 but only the metal film 20 is formed, the metal film 20 and the liquefied gas 30 may react and impurities may be mixed into the gas 35 in the housing portion 10.

The fluorinated passive film 22 may have at least a portion of a dissolution mark. The dissolution mark may be generated at the gas-liquid interface between the liquid phase 32 and the gas phase 34 in the liquefied gas 30. In addition, the gas-liquid interface may also be the gas-liquid interface between the liquid 33 and the gas 35 in the receiving portion 10. The durability of the fluorinated passive film 22 may also be managed according to the depth of the dissolution mark. The dissolution mark may refer to a portion where discoloration, unevenness, or coating peeling can be visually confirmed due to the contact between the gas-liquid interface and the metal film or fluorinated passive film of the receiving portion 10.

The container 100 containing liquefied gas can be stored, transported, etc. in an environment of, for example, 40°C or less, preferably 30°C or less, and more preferably 25°C or less. In addition, the temperature of the container 100 containing liquefied gas during operation can be set to, for example, 40°C or less, preferably 30°C or less, and more preferably 25°C or less. Under high temperatures during storage and transportation, the container of the present invention suppresses performance changes more than previous containers. This is also effective in summer. From this point of view, as one aspect of the present invention, it can be cited: the case of storing the container containing liquefied gas of the present invention at 30-40°C. That is, one form of the liquefied gas preservation method of the present embodiment may include the following steps: introducing liquefied gas 30 into the storage portion 10 of the above-mentioned container 100 containing liquefied gas; and preserving the container 100 containing liquefied gas filled with the liquefied gas 30 in a specific temperature environment. In the liquefied gas preservation method, the liquefied gas 30 may be a halogen-containing liquefied gas or a fluorine-containing liquefied gas. In addition, in the liquefied gas preservation method, the temperature environment in the preservation step is preferably, for example, above 25°C and below 40°C, and more preferably above 30°C and below 40°C.

An example of a method for manufacturing a container 100 containing liquefied gas includes the following steps: forming a metal film 20 on the inner surface 12 of a receiving portion 10; forming a fluoride passivation film 22 containing metal fluoride on the metal film 20; and introducing liquefied gas 30 into the receiving portion 10 on which the fluoride passivation film 22 is formed, thereby obtaining a container 100 containing liquefied gas, wherein the container 100 containing liquefied gas has a liquid 33 and a gas 35 in the receiving portion 10, the gas 35 containing a gas phase 34 of the liquefied gas 30, and the liquid 33 containing a liquid phase 32 of the liquefied gas 30 and a nickel element and/or a copper element.

The metal film 20 can be formed by a known method, for example, by a metal plating process such as electrolytic plating, electroless plating, or melt plating as described above. The plating solution used in the metal plating process can be appropriately selected according to the process method and the metal film 20 to be formed, and is not particularly limited.

Regarding the step of forming the fluoride passivation film 22 containing metal fluoride, the metal component contained in the metal film 20 can be reacted with a fluorine-containing gas as described above to obtain the fluoride passivation film 22 containing metal fluoride. As the fluorine-containing gas, for example, _F2 gas can be used. In the case of reacting with the fluorine-containing gas, for example, the contact can be carried out at 100°C or less. In addition, in the case where the fluoride passivation film 22 is a room-temperature fluoride passivation film, the room-temperature fluoride passivation film can be produced by allowing the fluorine-containing gas to flow into a container 100 containing liquefied gas at room temperature, the inner surface of which is formed with the metal film 20, and to contact the above-mentioned metal film 20. The above-mentioned "normal temperature" is not particularly limited as long as the temperature of the fluorine-containing gas is kept at a level where the reaction between the fluorine-containing gas and the metal film 20 does not proceed rapidly or significantly slow down. For example, it can be set within the range of 5 to 35°C, more preferably within the range of 10 to 35°C, and further preferably within the range of 10 to 30°C. In addition, when the operating environment is excessively high or low temperature, it can be heated or cooled to be within the above-mentioned normal temperature range.

In the introduction of the liquefied gas 30, the liquefied gas 30 in liquid form is introduced into the storage portion 10. In addition, before the introduction of the liquefied gas 30, if the inside of the container 100 containing the liquefied gas is replaced with an inert gas, it is more preferable because the gas other than the liquefied gas represented by the remaining fluorine-containing gas can be efficiently removed.

If the liquefied gas 30 is introduced after the fluoride passive film 22 is formed, a liquid 33 and a gas 35 containing the liquefied gas 30 are formed in the housing 10, and nickel and/or copper elements are supplied to the liquid 33. Although the details of the mechanism are unknown, it is speculated that the remaining metal elements from the metal film 20 attached to the fluoride passive film 22 are introduced into the liquid 33, or a part of the fluoride passive film 22 is dissolved into the liquid 33 due to the introduction of the liquefied gas 30. For example, when the liquid 33 in the housing 10 is substantially only the liquid phase 32 of the liquefied gas of HF or ClF ₃ , the metal film 20 or the fluoride passivation film 22 of the preferred embodiment of the present invention is not easily dissolved in the liquid phase 32, which can make the corrosion cycle of the inner wall of the container difficult to proceed. However, on the other hand, it can be inferred that since a trace amount of dissolution may occur, a trace amount of dissolution is generated when the liquefied gas 30 is introduced, and the nickel element and/or the copper element is supplied to the liquid 33. Furthermore, as a method for supplying the nickel element and/or copper element contained in the above-mentioned liquid 33, a supply source of the nickel element or the copper element may be arranged in advance in the liquid-contacting member or the housing portion 10 for filling the liquefied gas 30, and then the liquefied gas 30 may be introduced to supply the nickel element and/or the copper element to the liquid 33 from the supply source.

The above is an explanation of the implementation of the present invention, but these are examples of the present invention, and various structures other than the above can be adopted. In addition, the present invention is not limited to the above implementation, and changes and improvements within the scope of achieving the purpose of the present invention are included in the present invention. Implementation examples

Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited in any way to the description of these embodiments.

<Manufacturing of a container containing liquefied gas> (Example 1) A container containing liquefied gas 100 as shown in FIG. 1 is manufactured in the following order. First, a stainless steel container (housing portion 10) having an internal space for containing liquefied gas, a valve, and an outlet is prepared. Then, the entire inner wall of the container is nickel-plated (Ni concentration relative to the entire coating liquid = 15wt%) to form a nickel-plated film (metal film 20) with a thickness of 50 μm on its inner wall (inner surface 12) (plating treatment). Next, _F2 gas (99.9% by volume purity, fluorine-containing gas) is brought into contact with the nickel-plated film at room temperature to form a passivation film containing _NiF2 (a fluoride passivation film 22 containing metal fluoride) on the nickel-plated film (fluorine gas treatment). Thereafter, _F2 gas is removed from the interior of the container and replaced with He gas (inert gas) (replacement treatment). After the replacement, HF (liquefied gas) in a gaseous state is introduced into the internal space of the container, and HF in a liquid state is filled (liquefied gas filling treatment). By the above, a container containing liquefied gas is produced, in which the internal space of the container contains a liquid phase of 80% by volume of the liquefied gas.

(Example 2) A container containing liquefied gas is manufactured in the same manner as in Example 1, except that the Ni concentration in the plating liquid used in the nickel plating is higher than that in Example 1. (Example 3) A container containing liquefied gas is manufactured in the same manner as in Example 1, except that the material of the container is changed from stainless steel to manganese steel. (Example 4) A container containing liquefied gas is manufactured in the same manner as in Example 1, except that the metal plating is changed from nickel plating to copper plating. (Example 5) A container containing liquefied gas is manufactured in the same manner as in Example 4, except that the Cu concentration in the plating liquid used in the copper plating is higher than that in Example 4. (Example 6) A container containing liquefied gas was manufactured in the same manner as in Example 1, except that the type of liquefied gas was changed from HF to ClF _3. (Example 7) A container containing liquefied gas was manufactured in the same manner as in Example 2, except that the type of liquefied gas was changed from HF to ClF _3. (Example 8) A container containing liquefied gas was manufactured in the same manner as in Example 4, except that the type of liquefied gas was changed from HF to ClF _3. (Example 9) A container containing liquefied gas was manufactured in the same manner as in Example 5, except that the type of liquefied gas was changed from HF to ClF ₃ .

It was confirmed that in Examples 1 to 9, the liquefied gas (HF or ClF ₃ ) contained in the container was in a two-phase state including a liquid phase and a gas phase. In Examples 1 to 3 and 6 to 7, a passivation film including NiF ₂ was formed on the nickel-plated film, and in Examples 4 to 5 and 8 to 9, a passivation film including CuF ₂ was formed on the copper-plated film.

(Comparative Example 1) A container containing liquefied gas was produced in the same manner as in Example 1, except that the coating treatment was not performed but the fluorine gas treatment was performed. (Comparative Example 2) A container containing liquefied gas was produced in the same manner as in Example 6, except that the coating treatment was not performed but the fluorine gas treatment was performed.

[Table 1] Table 1 Types of liquefied gas Container material Metal film Metal concentration in liquid _F2 concentration in gas Etching speed Metal Type Initial period (remaining amount 100%) Remaining amount 80% Remaining amount 20% Initial period (remaining amount 100%) Remaining amount 80% Remaining amount 20% Initial period (remaining amount 100%) Remaining amount 80% Remaining amount 20% wt.ppm vol.ppm Set the initial speed to a relative value of 1 hour Embodiment 1 Stainless steel Nickel Nickel 0.1 85 370 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 2 Stainless steel Nickel Nickel 370 368 370 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 3 HF Manganese steel Nickel Nickel 0.8 68 370 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 4 Stainless steel Copper Copper 0.1 30 100 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 5 Stainless steel Copper Copper 3 25 100 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 6 Stainless steel Nickel Nickel 0.5 123 500 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 7 ClF ₃ Stainless steel Nickel Nickel 280 360 500 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 8 Stainless steel Copper Copper 0.3 15 150 ＜1 ＜1 ＜1 1.0 1.0 1.0 Embodiment 9 Stainless steel Copper Copper 5 47 150 ＜1 ＜1 ＜1 1.0 1.0 1.0 Comparison Example 1 HF Stainless steel - Nickel and copper ＜1 ppb ＜1 ppb ＜1 ppb 120 12 ＜1 1.0 0.9 0.8 Comparison Example 2 ClF ₃ Stainless steel - Nickel and copper ＜1 ppb ＜1 ppb ＜1 ppb 56 5 ＜1 1.0 0.9 0.8

Based on the following evaluation items, the containers containing liquefied gas in each embodiment and each comparative example were evaluated.

(Metal concentration in liquid) The metal concentration (wt.ppm) of nickel and copper contained in the liquid in the container was determined by ICP emission spectrometry. In addition, regarding the metal concentration, the values when the remaining amount of liquid in the container was 80% by volume relative to the initial period when the container was just filled with liquefied gas, the gas containing liquefied gas was slowly released from the outlet by opening the valve of the container, and the remaining amount of liquid in the container was 20% are shown in Table 1. Furthermore, in the "Metal Type" of "Metal Concentration in Liquid" in Table 1, nickel or copper is recorded. For those examples 1 to 9 where only one element is recorded, the unrecorded element does not reach 1 ppb (does not reach the detection limit). In Comparative Examples 1 and 2, the concentration of either nickel or copper did not reach 1 ppb (not reaching the detection limit) at the initial stage, when the residual amount was 80%, and when the residual amount was 20%, and neither nickel or copper was confirmed in the liquid.

( _F2 concentration in gas) The _F2 concentration (wt. Vol) contained in the gas in the container was measured by ICP emission spectrometry. In addition, regarding the _F2 concentration, the gas (gas) just released from the outlet was used as the measurement object. The values of the initial period when the liquefied gas was just filled into the container, the remaining amount of liquid in the container when the valve of the container was opened and the gas containing liquefied gas was slowly released from the outlet so that the volume of the remaining liquid in the container was 80% relative to the initial period, and the remaining amount of liquid in the container was 20% are shown in Table 1.

Furthermore, in Examples 1 to 9, the HF concentration or ClF ₃ concentration in the initial period was measured by ICP emission spectrometry with the gas just released from the outlet as the measurement object. It was confirmed that in any of the examples, the HF concentration or ClF ₃ concentration in the gas in the initial period was 99.9% by volume or more.

(Etching speed) First, the structure of the etching device is explained. The reaction chamber is equipped with a stage for supporting the sample. The sample used is a 6-inch silicon substrate on which a silicon oxide film (20 nm) is formed, and a polysilicon film (30 μm) is formed thereon. The stage is equipped with a stage temperature regulator that can adjust the temperature of the stage. The first gas pipe for introducing gas and the second gas pipe for exhausting gas are connected to the reaction chamber. The etching gas supply system is connected to the first gas pipe via the first valve to supply the above-mentioned substrate processing gas to the reaction chamber. The vacuum pump is connected to the second gas pipe via the second valve to exhaust the gas. The pressure inside the reaction chamber is controlled by the second valve based on the indication value of the pressure gauge attached to the reaction chamber.

Next, the operation method of the etching device is explained. Place the sample on the stage, replace the vacuum in the reaction chamber and the first and second gas pipes until the pressure reaches 1.5 kPa, and then set the temperature of the stage to a specific value (25°C). After confirming that the temperature of the stage has reached the specific value, open the first and second valves, set the pressure of the etching gas supply system to a specific pressure (100 Pa), and introduce the liquefied gas stored in the container containing the liquefied gas into the reaction chamber through the first gas pipe as the substrate processing gas. The total flow rate of the substrate processing gas at this time is set to 100 sccm.

After a specific time (etching process time, 1 minute) has passed since the substrate processing gas was introduced, the introduction of the substrate processing gas was stopped, the interior of the reaction chamber was replaced with a vacuum, and then the sample was taken out to measure the etching rate.

Using the silicon substrate (sample) with polysilicon film, the film thickness of the polysilicon film before etching and the film thickness of the polysilicon film after etching were measured at 5 locations, and the etching amount (the film thickness difference before etching and after etching) of each measured location was obtained. The etching speed (nm/min) was calculated based on the average etching amount of each measured location and the etching time.

Regarding the etching rate, when the initial period when the container is just filled with liquefied gas is set to 1.0, the relative values are shown in Table 1 when the remaining amount of liquid in the container is 80% by volume relative to the initial period when the valve of the container is opened and the gas is slowly released from the outlet and the remaining amount of liquid in the container is 20%.

As described above, nickel or copper was confirmed in the liquid in the container containing liquefied gas in Examples 1 to 9, indicating that the composition of the gas in the container can be kept roughly constant from the initial period just after opening to the end of use. In addition, the etching speed of the gas in any of the embodiments is roughly constant, which shows that the performance change of the liquefied gas can be suppressed compared with Comparative Examples 1 and 2. In addition, the liquefied gas filled in the container containing liquefied gas in each embodiment can be preferably used for semiconductor applications such as etching gas.

This application claims priority based on Japanese Patent Application No. 2022-199993 filed on December 15, 2022, and all of its disclosure is incorporated herein.

10: Receptacle 12: Inner surface 20: Metal film 22: Fluoride passive film 30: Liquefied gas 32: Liquid phase 33: Liquid 34: Gas phase 35: Gas 40: Valve 50: Removal port 100: Container containing liquefied gas α: Area

Fig. 1(a) is a cross-sectional view schematically showing an example of the structure of a container containing liquefied gas according to the present embodiment. Fig. 1(b) is an enlarged view of a region α of (a).

10: Containment Department

12: Inner surface

20:Metal film

22: Fluorinated passive film

30: Liquefied gas

32: Liquid phase

33: Liquid

34: Gas phase

35: Gas

40: Valve

50: Take the exit

100: Containers containing liquefied gas

α: Area

Claims (13)

A container containing liquefied gas, comprising: a container, and liquefied gas contained in the container, and the container has a metal film on the inner surface, and a fluoride passivation film containing metal fluoride on the metal film, the container contains liquid and gas, the gas contains the gas phase of the liquefied gas, the liquid contains the liquid phase of the liquefied gas, and nickel element and/or copper element. For example, a container containing liquefied gas as in claim 1, wherein the total content of the nickel element and copper element in the liquid measured by ICP emission spectrometry is greater than 10 wt ppb and less than 1000 wt ppm. A container containing liquefied gas as claimed in claim 1 or 2, wherein the liquefied gas is HF or ClF ₃ . For containers containing liquefied gas as in claim 1 or 2, more than 99.9% by volume of the above-mentioned gas is in the gas phase of the above-mentioned liquefied gas. For containers containing liquefied gas as claimed in claim 1 or 2, the amount of _F2 in the above-mentioned gas does not reach 100 volume ppm. A container containing liquefied gas as claimed in claim 1 or 2, wherein the housing portion comprises one or more selected from the group consisting of stainless steel, carbon steel, manganese steel, nickel steel, and aluminum steel. For example, a container containing liquefied gas as claimed in claim 1 or 2, wherein the metal film has a coating. A container containing liquefied gas as claimed in claim 1 or 2, wherein the metal film contains nickel and/or copper as a main component. For a container containing liquefied gas as in claim 1 or 2, the thickness of the metal film is between 1 μm and 300 μm. For example, a container containing liquefied gas as claimed in claim 1 or 2, wherein the above-mentioned fluorinated passive film is a room temperature fluorinated passive film. A container containing liquefied gas as claimed in claim 1 or 2, wherein at least a portion of the above-mentioned fluorinated passive film has dissolution marks. A method for manufacturing a container containing liquefied gas, which is a method for manufacturing a container containing liquefied gas, comprising a storage portion and liquefied gas stored in the storage portion. The manufacturing method comprises the following steps: forming a metal film on the inner surface of the storage portion; forming a passivation fluoride film containing metal fluoride on the metal film; and introducing the liquefied gas into the storage portion on which the passivation fluoride film is formed, thereby obtaining a container containing liquefied gas, wherein the container containing liquefied gas has liquid and gas in the storage portion, the gas contains a gas phase of the liquefied gas, and the liquid contains a liquid phase of the liquefied gas and nickel and/or copper elements. In the method for manufacturing a container containing liquefied gas as claimed in claim 12, the step of forming the above-mentioned fluoride passivation film is the following step: allowing fluorine-containing gas to flow into the above-mentioned receiving portion at room temperature and contact the above-mentioned metal film.