Metal materials for high-purity hydrogen fluoride storage containers with improved scratch resistance and their manufacturing method

Abstract

This invention relates to a container metal material for storing high-purity hydrogen fluoride and a method for manufacturing the same. In particular, it relates to a container metal material for storing high-purity hydrogen fluoride and a method for manufacturing the same, which improves corrosion resistance and scratch resistance by including a graphite layer on the surface of a metal substrate and a nickel fluoride film formed in the structural defect space within the graphite layer, thereby enabling the storage and transfer of corrosive gases, i.e., hydrogen fluoride, without pollution and with high purity.

Description

Technical Field

[0001] This invention relates to a metal material for a high-purity hydrogen fluoride storage container with improved scratch resistance, and more particularly to a material and a method for manufacturing a container for storing high-purity hydrogen fluoride that can store and transfer corrosive gases, namely hydrogen fluoride, for a long time with high purity without pollution by improving corrosion resistance and scratch resistance. Background Technology

[0002] In the manufacturing processes of semiconductor components, microelectromechanical systems (MEMS) devices, thin film transistor (TFT) panels for liquid crystal displays, and solar cell panels, approximately 150 different gases are required depending on the characteristics of processes such as etching, film deposition, and cleaning.

[0003] For example, semiconductor manufacturing processes require the use of highly reactive and corrosive halogen-based special gases such as hydrogen chloride (HCl), boron trichloride (BCl3), fluorine (F2), nitrogen trifluoride (NF3), chlorine trifluoride (ClF3), hydrogen bromide (HBr), and hydrogen fluoride (HF). In particular, highly reactive corrosive gases, such as hydrogen fluoride (HF), are required in etching and cleaning processes. Due to the increasing integration density of semiconductor engineering, higher purity hydrogen fluoride is needed to minimize defect rates.

[0004] However, hydrogen fluoride is a highly reactive and corrosive gas that is easily hydrolyzed by moisture in the air. It also easily corrodes the metal materials or metal coating structures that make up the storage containers, valves, pipes and reaction chambers used to process hydrogen fluoride. As mentioned above, corrosion will lead to contamination and a decrease in the purity of the stored and supplied hydrogen fluoride, making it unusable in semiconductor engineering.

[0005] To address the problems mentioned above, a corrosion-resistant material for handling hydrogen fluoride has been developed.

[0006] As an example, Japanese Patent No. 3891815 (March 14, 2007) discloses an alloy with excellent corrosion resistance, containing 4.0 to 5.0% by mass of Mg and 0.02 to 0.1% by mass of Cr, with the contents of impurities Si, Fe, Cu, Mn, Zn, and Ni limited to less than 0.1% by mass each, and the remainder consisting of Al and other impurities. This is an aluminum alloy for coating formation, and the prior art discloses that the alloy and alloy material are suitable for use as materials for semiconductor manufacturing devices. However, this prior art is limited to aluminum alloys, and the manufacturing and purification processes to achieve the composition described above are complex, and it has the problem of difficulty in maintaining corrosion resistance when scratched due to external stimuli.

[0007] In addition, as materials for devices that treat hydrogen fluoride, Hastelloy, a nickel alloy with extremely high corrosion resistance, and Inconel, a nickel alloy with excellent heat resistance and corrosion resistance with 15% chromium added, can be considered. However, as mentioned above, the high price and poor machinability of these alloys would lead to a decrease in economic efficiency and engineering efficiency.

[0008] Therefore, fluorine gas can usually be used to passivate the surface of nickel metal, thereby exhibiting extremely high corrosion resistance to corrosive gases, including hydrogen fluoride.

[0009] However, because the passivation layer using fluorine gas, as described above, is not thick enough and is prone to scratches, Korean Patent No. 10-0308688 (November 30, 2001) proposes a method to form a thicker passivation layer. This involves forcibly oxidizing the surface of a metal material or nickel alloy coating made of nickel or a nickel alloy, followed by passivation of the oxidized layer using a substance such as fluorine. This results in a passivation layer of 1 μm or more on the surface, thereby improving its corrosion resistance. However, because this prior art requires forced oxidation of the nickel or nickel alloy coating and the formation of a considerably thick fluoride layer of 1 μm or more, the process is complex, the adhesion between the fluoride layer and the base material decreases, and it is difficult to achieve satisfactory wear resistance and durability through the fluoride layer and maintain it for a considerable period of time.

[0010] The present invention aims to solve the problems described above. It has been discovered that by forming the outermost layer of the inner surface of the storage container using a graphite layer with excellent scratch resistance and forming a nickel fluoride layer on defects such as pinholes that may occur in the graphite layer, corrosion resistance and scratch resistance can be improved, thereby enabling long-term storage of corrosive substances such as hydrogen fluoride. Thus, the present invention is completed.

[0011] [Patent Literature]

[0012] (Patent Document 1) Japanese Patent No. 3891815 (Issuance Date: March 14, 2007)

[0013] (Patent Document 2) Korean Patent No. 10-0308688 (Issuance Date: 2001.11.30) Summary of the Invention

[0014] Technical issues

[0015] The present invention aims to provide a metal material for storing high-purity hydrogen fluoride, which improves corrosion resistance and scratch resistance even when the outermost surface layer is fluorinated, without forming a fluorinated layer of considerable thickness, thereby enabling the storage and transfer of hydrogen fluoride in high purity.

[0016] Furthermore, the present invention aims to provide a container for storing high-purity hydrogen fluoride, which is made of the metal material used in the container.

[0017] Furthermore, the present invention aims to provide a method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride.

[0018] Technical solution

[0019] To address the aforementioned issues, the present invention provides a metal material for a container used to store high-purity hydrogen fluoride, characterized in that it comprises: a metal substrate; a nickel plating layer formed on the surface of the substrate; a graphite layer formed on the surface of the nickel plating layer; and a nickel fluoride film formed in a structural defect space within the graphite layer.

[0020] In one embodiment of the present invention, the thickness of the graphite layer may be 2 to 100 μm.

[0021] Furthermore, the present invention provides a method for manufacturing a metal material for a container for storing high-purity hydrogen fluoride, characterized in that it includes: (1) a step of forming a nickel plating layer on a metal substrate; (2) a step of forming a graphite layer on the surface of the nickel plating layer; (3) a step of inserting nickel into a structural defect space within the graphite layer by replating nickel on the upper part of the graphite layer, and removing the nickel plating film formed on the upper part of the graphite layer; and (4) a step of forming a graphite layer containing nickel fluoride by fluorinating the nickel inserted into the structural defect space within the graphite layer after completing step (3).

[0022] The thickness of the graphite layer can be from 2 to 100 μm.

[0023] Furthermore, the graphite layer in step (2) can be formed by reacting the carbon source reaction gas with the surface of the nickel plating layer.

[0024] In one embodiment of the invention, the fluorination process in step (4) can be carried out using at least one gas selected from the group consisting of fluorine (F2), hydrogen fluoride (HF), chlorine trifluoride (ClF3), nitrogen fluoride (NF3) and fluoromethane (CH3F), or using a gas diluted with an inert gas.

[0025] Furthermore, the present invention provides a container made of the aforementioned metallic material for storing high-purity hydrogen fluoride.

[0026] Technical effect

[0027] The container material of the present invention forms a multilayer coating on a substrate and uses a graphite layer as the outermost layer. The density of the graphite layer is reinforced by forming a nickel fluoride film in the pores that may be formed on the graphite layer. As a result, the scratch resistance of the graphite layer can significantly reduce the possibility of coating damage such as perforation and cracking caused by external environment and impact. Moreover, even when a passivation film, i.e. a nickel fluoride layer, is formed with a relatively thin thickness, sufficient corrosion resistance can be maintained for a long time. Attached Figure Description

[0028] Figure 1 The container material for storing high-purity hydrogen fluoride according to the present invention is illustrated.

[0029] Figure 2 A method for manufacturing the container material according to the present invention has been illustrated. Detailed Implementation

[0030] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Generally, the nomenclature methods known and commonly used in this art are used in this specification.

[0031] Throughout this specification, when a part is described as "including" a constituent element, unless otherwise expressly stated to the contrary, it does not mean that other constituent elements are excluded, but rather that other constituent elements may be included.

[0032] Throughout this specification, "structural defect space of graphite layer" refers to spaces such as perforations and cracks that may occur during the formation of graphite layer.

[0033] The present invention will now be described in detail.

[0034] The present invention provides a metal material for a container for storing high-purity hydrogen fluoride, characterized in that it comprises: a metal substrate; a nickel plating layer formed on the surface of the substrate; a graphite layer formed on the surface of the nickel plating layer; and a nickel fluoride layer formed in the pores of the graphite layer.

[0035] Figure 1 The metal material for a container used for storing high-purity hydrogen fluoride according to the present invention has been illustrated, and will be referred to below. Figure 1 A detailed explanation will be provided.

[0036] See Figure 1 The container metal material of the present invention forms a nickel plating layer on the surface of a metal substrate.

[0037] The metal substrate is not specifically limited, as long as it has the stability and density to be used as a container. It can be selected from aluminum, aluminum alloy, nickel, nickel alloy and stainless steel, preferably stainless steel, and the thickness of the metal substrate is within the range of the composite gas stability standard.

[0038] The nickel plating layer formed on the surface of the metal substrate can be formed by electrolytic plating or non-electrolytic plating. In this case, the nickel can be pure Ni or Ni-P, Ni-B, and Ni-C doped with P, B, and C.

[0039] The thickness of the nickel plating layer can be formed in the range of 5 to 60 μm. If the thickness of the nickel plating layer is less than 5 μm, it may be difficult to effectively form an uneven surface for improving adhesion to the graphite layer described later. If the thickness exceeds 60 μm, it may lead to reduced economic efficiency due to the excessive thickness of the formed nickel film. Preferably, the thickness of the nickel plating layer is 30 to 40 μm.

[0040] In addition, relative to 100 parts by weight of nickel, the amount of P, B and C doped into nickel may be 0.01 to 5 parts by weight.

[0041] The nickel plating layer is applied to form the graphite layer described later, and therefore a certain surface roughness is desirable. Surface roughness refers to the degree of micro-unevenness formed on the metal surface during finishing, caused by factors such as the suitability of the tools and methods used in processing, grooves formed by surface scratches, and rust. It can be determined according to KSB 0161 using the maximum height (Rmax), ten-point average roughness (Rz), and centerline average roughness (Ra). As mentioned above, surface roughness may affect the physical and chemical properties of the contact area. In this invention, the centerline average roughness (Ra) of the metal substrate can be in the range of 0.5–3 μm, preferably around 1.0–2.0 μm. When the average surface roughness (Ra) of the nickel plating layer meets the aforementioned range, the adhesion between the graphite layer and the nickel plating layer described later can be maximized.

[0042] The nickel and the like are metals that exhibit activities such as dehydrogenation. When they come into contact with unsaturated hydrocarbons such as ethylene and acetylene at high temperatures, they can remove hydrogen from the carbides and cause carbon to deposit.

[0043] The graphite layer formed on the surface of the nickel plating exhibits extremely high adhesion to the nickel plating. Considering the durability dependent on corrosion resistance and film density, a thickness of 2–100 μm, preferably 5–50 μm, can prevent coating loss due to external impacts. A graphite layer thickness below 5 μm may lead to decreased scratch resistance, while a thickness exceeding 100 μm may result in decreased adhesion to the nickel plating.

[0044] Due to the properties of the material, the graphite layer may contain structural defects (blank spaces) due to the unintended formation of blank spaces, including pores, within the graphite layer. As a result, its density is low, and if only the graphite layer is used to form the outermost layer, corrosion may occur in the inner layers due to the penetration of substances such as HF into the pores of the graphite layer. Therefore, it is not suitable as a container material for storing and transporting corrosive gases, such as hydrogen fluoride.

[0045] Therefore, the present invention provides scratch resistance by using the graphite layer as the outermost surface layer, and further improves corrosion resistance by plating nickel on the surface of the graphite layer to address corrosion problems induced by structural defects in the graphite layer. Through the nickel plating described above, the nickel plating layer can penetrate to the locations of structural defects such as the aforementioned pores, thereby filling the pores in the graphite layer and removing the structural defects.

[0046] Next, the nickel plating layer formed on the outermost layer is removed by etching or grinding, thereby minimizing the presence of the graphite layer on the outermost surface. Through the processing described above, most of the outermost surface will consist of a graphite layer, but small pores and other defects present on the surface of the graphite layer will be blocked by the nickel plating layer.

[0047] When the surface is subjected to fluorination treatment under the conditions described above, a nickel fluoride layer is formed because the nickel plating layer present in the pores of the graphite layer is passivated. This not only improves the density of the graphite layer by removing structural defects, but also improves scratch resistance and thereby increases durability and lifespan, even when the thickness of the formed nickel fluoride film is less than the thickness usually required to improve corrosion resistance.

[0048] Generally speaking, when defects such as cracks and perforations occur in the passivation layer, nickel fluoride, or fluorine layer due to external environment, corrosive gases, oxygen, and moisture can move between the defects and induce corrosion of the substrate. Therefore, the passivation layer needs to be formed with a considerable thickness to prevent corrosion-inducing substances from moving to the substrate.

[0049] However, by forming a nickel fluoride layer in the structural defect space such as pores within the graphite layer, the present invention can prevent the nickel fluoride layer from directly contacting physical stimuli from the external environment. Therefore, the thickness of the nickel fluoride layer, which is related to durability and mechanical strength, is no longer a major factor. Moreover, thanks to the scratch resistance of the graphite layer, external environmental stimuli are not directly applied to the nickel fluoride layer, thereby significantly reducing the occurrence of defects such as cracks and perforations caused by external stimuli such as scratches.

[0050] As described above, the container material of the present invention forms a multilayer coating on a substrate and uses a graphite layer containing a nickel fluoride film as the outermost layer. Therefore, the possibility of coating damage such as perforation and cracking caused by external environment and impact can be significantly reduced, thereby maintaining corrosion resistance for a long time. It is suitable for storage containers of highly corrosive hydrogen fluoride. Moreover, storage containers for hydrogen fluoride and the like made using the metal material of the present invention have excellent long-term durability compared with storage containers made using other materials.

[0051] Furthermore, the present invention provides a method for manufacturing a metal material for a container for storing high-purity hydrogen fluoride, characterized in that it includes: (1) a step of forming a nickel plating layer on a metal substrate; (2) a step of forming a graphite layer on the surface of the nickel plating layer; (3) a step of inserting nickel into a structural defect space within the graphite layer by replating nickel on the upper part of the graphite layer, and removing the nickel plating film formed on the upper part of the graphite layer; and (4) a step of forming a graphite layer containing nickel fluoride by fluorinating the nickel inserted into the structural defect space within the graphite layer after completing step (3).

[0052] Figure 2 This is an engineering drawing illustrating a method for manufacturing a metal material for a container according to the present invention, which will be referred to below. Figure 2 Please provide an explanation.

[0053] See Figure 2 Step (1) is the step of forming a nickel plating layer on a metal substrate, wherein nickel plating is performed by electrolysis or non-electrolysis after removing impurities present on the surface by pretreatment of the substrate surface.

[0054] The pretreatment of the metal substrate is to remove impurities present on the surface of the metal substrate, thereby improving the adhesion between the substrate and the coating film formed on the substrate and preventing the formation of an unnecessary oxidation environment. It can be carried out by general pretreatment methods such as chemical washing, commercial degreasing and dry etching. At this time, the metal substrate is not particularly limited, as long as it has the stability and density suitable for use as a container. It can be selected from aluminum, aluminum alloy, nickel, nickel alloy and stainless steel, preferably stainless steel, and the thickness of the metal substrate is within the range of the composite gas stability standard.

[0055] The thickness and surface roughness of the nickel plating can be the same as those described above.

[0056] In this invention, step (2) is the step of forming a graphite layer on the surface of the nickel plating layer, wherein the thickness of the graphite layer is 2 to 100 μm, preferably 5 to 50 μm.

[0057] The graphite layer can be formed by coating an aqueous solution containing dispersed carbon material onto a surface and then drying it, or by directly extruding the carbon material onto the surface. However, the graphite layer can be formed more effectively by utilizing the dehydrogenation properties of nickel. Specifically, carbon can be deposited on the nickel plating by simultaneously supplying a carbon source reaction gas and heating the plating, followed by further heating to an even higher temperature to graphitize the carbon and form a graphite layer. In this case, the surface roughness of the nickel plating can be artificially increased to improve carbon deposition efficiency.

[0058] At this point, the temperature for forming the graphite layer can be in the range of 500–1000°C, preferably in the range of 600–800°C. The carbon source reactant gas can be an aliphatic hydrocarbon molecule containing one or more of acetylene, ethylene, ethane, and propane, or an aromatic hydrocarbon molecule containing one or more of benzene, naphthalene, anthracene, phenanthrene, and pyrene. The carbon source reactant gas forms the graphite layer by reacting with the nickel surface. Furthermore, the carbon source reactant gas is preferably supplied to the inert transfer gas at a concentration of 0.1–50 vol%.

[0059] In this invention, step (3) is the step of forming a nickel plating film on the formed graphite layer. After sufficient nickel plating is performed on the upper part of the graphite layer so that nickel is inserted into and plated into the structural defect spaces such as small holes in the graphite layer, the nickel plating film formed on the upper part of the graphite layer is removed.

[0060] In step (3), not only is the density of the graphite layer improved by filling the structural defect space within the graphite layer with nickel plating, but the nickel plating film formed on the upper part of the graphite layer is also removed by electrolytic grinding or etching, thereby making the graphite layer the outermost layer and improving its scratch resistance.

[0061] In this invention, step (4) is a step of forming a graphite layer containing nickel fluoride by fluorinating the nickel inserted into the structural defect space of the graphite layer after completing step (3). The fluorination treatment is not subject to any special limitation and can be carried out by general methods. However, in order to improve the formation efficiency and corrosion resistance of nickel fluoride, the temperature during fluorination is 200 to 500°C.

[0062] The fluorinating gas used in the fluorination reaction can be, for example, at least one gas selected from the group consisting of fluorine (F2), hydrogen fluoride (HF), chlorine trifluoride (ClF3), nitrogen fluoride (NF3), and fluoromethane (CH3F), or a gas diluted with an inert gas.

[0063] As a diluent gas, inert gases such as nitrogen and helium can be used, with nitrogen being preferred. When using the diluted fluorinated gas, its concentration can be set to an appropriate amount according to the reaction conditions. For example, considering factors such as cost, it is advisable to use a fluorine concentration of approximately 10%.

[0064] The present invention will now be described in more detail with reference to the embodiments. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited thereto.

[0065] <Example>

[0066] Manufacturing of hydrogen fluoride storage containers

[0067] Example 1

[0068] A commercially available stainless steel high-pressure vessel (316L, 5mm thick) was used as the metal substrate, and the substrate was first pretreated. After degreasing and washing the inner surface of the substrate with alkali and alcohol, it was washed with high-purity deionized water (DI water). Pretreatment was completed by drying with hot N2. After immersing the metal substrate in a reaction chamber and injecting 45 sccm of Ar gas into the chamber, etching was performed by applying a voltage of 1100V and a current of 0.2A to the ion gun.

[0069] Electroless plating was performed on the pretreated metal substrate surface using an aqueous solution containing graphite, nickel sulfate (NiSO2) metal salt, and sodium hypophosphite (NaH2PO2) reducing agent to form a 10 μm thick carbon-doped Ni coating on the metal substrate surface. Next, the surface roughness (Ra) of the Ni coating was adjusted to 1 μm.

[0070] Next, carbon is deposited on the surface of the carbon-doped Ni film by heating to 500°C while supplying acetylene to the Ni coating, and then the deposited carbon is graphitized by further heating to 800°C, thereby forming a graphite layer with a thickness of 10 μm.

[0071] Ni is plated onto the upper surface of the graphite layer, including the blank spaces within the graphite layer, by electroless plating with an aqueous solution containing nickel sulfate (NiSO2) metal salt and sodium hypophosphite (NaH2PO2) reducing agent. Then, the Ni plating film formed on the surface of the graphite layer is removed, so that the graphite layer is finally exposed as the outermost layer.

[0072] Finally, the outermost layer is fluorinated at 300°C for 5 hours using a mixed gas consisting of 10% F2 and the remainder Ar, thereby producing a container material in which a NiF2 film is formed in the empty space within the graphite layer while making the graphite layer the outermost layer.

[0073] Comparative Example 1

[0074] Based on Example 1, except that after forming nickel plating on the upper part of the graphite layer, the process of removing the nickel plating film on the upper part of the graphite layer is not performed, but fluorination treatment (F2) is directly performed to form a 200nm thick NiF2 film on the surface of the graphite layer and make the graphite layer contain blank spaces, the container material was manufactured in the same way as in Example 1.

[0075] Comparative Example 2

[0076] Except for omitting the niobium layer and fluorination process, the container material was manufactured using the same method as in Example 1.

[0077] Comparative Example 3

[0078] Except for forming a 200 nm thick NiF2 film on the Ni coating surface by omitting the graphite layer formation process, the container material was manufactured in the same manner as in Example 1.

[0079] Corrosion resistance and scratch resistance tests

[0080] For the manufactured Example 1 and Comparative Examples 1 to 3, corrosion resistance and scratch resistance tests were performed according to the method described below, and the results are shown in Table 1 below.

[0081] Corrosion resistance test: After the container material test piece is placed in a sealed container, an HF environment is created inside the container by supplying HF to the container. Then, after 30 days, the surface of the test piece is observed using an electron microscope.

[0082] Scratch resistance test: The manufactured container material specimens were subjected to a scratch test using a scratch tester equipped with a diamond tip.

[0083] Table 1

[0084]

[0085] (◎: Excellent, ○: Good, △: Average, ×: Poor)

[0086] As shown in Table 1, when a nickel fluoride film is formed in the blank space of the graphite layer (Example 1), both corrosion resistance and scratch resistance are excellent.

[0087] In contrast, in the case where a nickel fluoride film is formed on the surface of the graphite layer (Comparative Example 1) and in the case where the graphite layer is omitted (Comparative Example 3), defects such as perforations and cracks are easily formed on the coating due to the pressure and stimulation caused by the external environment, resulting in a significant decrease in corrosion resistance.

[0088] Furthermore, in the absence of a nickel fluoride film (Comparative Example 2), although scratch resistance is present, corrosion resistance is poor.

[0089] In the foregoing description, the embodiments illustrated in the accompanying drawings have been used to illustrate the present invention. However, these are merely exemplary embodiments, and those skilled in the art should understand that various modifications or equivalent embodiments can be implemented based on them. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0090] Industrial availability

[0091] This invention relates to a metal material for storing high-purity hydrogen fluoride, and a method for manufacturing the same, which improves scratch resistance and allows for the storage and transfer of corrosive gases, namely hydrogen fluoride, without pollution and with high purity over long periods of time. This invention can be applied and utilized in various industrial fields, such as semiconductor components, microelectromechanical systems (MEMS) devices, thin-film transistor (TFT) panels for liquid crystal displays, and solar cell panels, which are suitable for high-purity hydrogen fluoride.

Claims

1. A method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride, characterized in that, include: (1) The step of forming a nickel plating layer on a metal substrate; (2) The step of forming a graphite layer on the surface of the nickel plating; (3) The step of inserting nickel into the structural defect space within the graphite layer by replating nickel on the upper part of the graphite layer, and removing the nickel plating formed on the upper part of the graphite layer. as well as (4) The step of forming a graphite layer containing nickel fluoride by fluorinating the nickel inserted into the structural defect space within the graphite layer after completing step (3).

2. The method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride according to claim 1, characterized in that: The thickness of the graphite layer is 2 to 100 μm.

3. The method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride according to claim 1, characterized in that: The graphite layer in step (2) is formed by reacting the carbon source reaction gas with the surface of the nickel plating layer.

4. The method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride according to claim 1, characterized in that: The fluorination process in step (4) is carried out using at least one gas selected from the group consisting of fluorine, hydrogen fluoride, chlorine trifluoride, nitrogen trifluoride and fluoromethane.

5. The method for manufacturing a metal material for a container used to store high-purity hydrogen fluoride according to claim 1, characterized in that: The fluorination process in step (4) is carried out using an inert gas to dilute a gas selected from the group consisting of fluorine, hydrogen fluoride, chlorine trifluoride, nitrogen trifluoride, and fluoromethane.

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