Method for producing purified fluorine-containing gas composition, method for producing semiconductor device, and etching apparatus

Abstract

Provided are: a method for producing a purified fluorine-containing gas composition capable of suppressing contamination of Cr on a treatment target surface when etching is performed; a method for producing a semiconductor device in which the method for producing the purified fluorine-containing gas composition is applied; and an etching apparatus. The present invention pertains to a method for producing a purified fluorine-containing gas composition, the method comprising a contact step for bringing, into contact with a metal fluoride that is solid at 30°C or lower, a crude fluorine-containing gas composition containing a fluorine-containing gas composition that includes 98 vol% or more of a fluorine-containing molecule excluding hydrogen fluoride and that has a Cr-concentration of 100 mass ppb or less.

Description

Method for producing purified fluorine-containing gas composition, method for producing semiconductor device, and etching apparatus

[0001] The present disclosure relates to a method for producing a purified fluorine-containing gas composition, a method for producing a semiconductor device to which the method for producing a purified fluorine-containing gas composition is applied, and an etching apparatus.

[0002] Fluorine gas compositions such as fluorine gas are widely used as cleaning gases for etching substrates or for thin film formation devices such as CVD (Chemical Vapor Deposition) in the manufacturing processes of semiconductor devices, MEMS (Micro Electro Mechanical Systems) devices, TFT (Thin Film Transistor) panels for liquid crystal displays, solar cells, etc., or as fluorinating agents for synthesizing fluorine chemical products.

[0003] In the manufacture of semiconductor devices, the technical difficulty of processing is increasing year by year due to the development of miniaturization and high-integration technologies. Under these circumstances, there is concern that impurities contained in semiconductor device materials may cause problems in the semiconductor device manufacturing process, such as reducing product yield. Therefore, there is a demand for high purity fluorine gas to be used, and the required level is particularly high, such as the need to reduce metal impurities, which have a significant impact on electrical properties, to less than 10 ppb by mass.

[0004] For example, Patent Document 1 discloses that when the concentration of hydrogen fluoride in fluorine gas is 50 ppm by volume or more, metal components contained in the fluorine gas react with hydrogen fluoride and are adsorbed onto a solid metal fluoride and removed together with the hydrogen fluoride, thereby enabling the fluorine gas to be purified.

[0005] JP 2017-141149 A

[0006] The present inventors had believed that the method described in Patent Document 1 sufficiently removed metal components such as Cr. However, when etching was actually performed using the purified fluorine-containing gas composition obtained by the method described in Patent Document 1, it was surprisingly found that there was room for improvement in terms of suppressing the incorporation of Cr into the treated surface.

[0007] The present disclosure aims to solve the above-mentioned problem newly discovered by the present inventors, and to provide a method for producing a purified fluorine-containing gas composition that can suppress the incorporation of Cr into the surface to be treated during etching, a method for producing a semiconductor device that applies the method for producing a purified fluorine-containing gas composition, and an etching apparatus.

[0008] As a result of extensive research, the present inventors have found that even a fluorine-containing gas composition with an extremely low Cr concentration can be converted into a purified fluorine-containing gas composition with an even higher purity by contacting it with a solid metal fluoride at 30°C or less, and that when etching is performed using this purified fluorine-containing gas composition, it is possible to suppress the incorporation of Cr into the treated surface, thereby completing the present disclosure.

[0009] That is, the present disclosure (1) relates to a method for producing a purified fluorine-containing gas composition, which includes a contacting step of contacting a crude fluorine-containing gas composition containing a fluorine-containing gas composition that contains 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and has a Cr concentration of 100 ppb by mass or less, with a solid metal fluoride at 30°C or less.

[0010] The present disclosure (2) relates to a method for producing a purified fluorine-containing gas composition according to the present disclosure (1), wherein the crude fluorine-containing gas composition is contacted with a solid metal fluoride at a temperature below 0°C in the contacting step.

[0011] The present disclosure (3) relates to the method for producing a purified fluorine-containing gas composition according to the present disclosure (1), wherein the crude fluorine-containing gas composition is brought into contact with a solid metal fluoride at −20° C. or lower in the contacting step.

[0012] The present disclosure (4) is a method for preparing a fluorine-containing molecule comprising: ２ , ClF, ClF ３ , IF ５ , IF ７ , BrF ３ , BrF ５ , N.F. ３ , W.F. ６ , SiF ４ , C.F. ４ , S.F. ６ , and BF ３The present invention relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosure (1) to (3), wherein the purified fluorine-containing gas composition is at least one selected from the group consisting of:

[0013] The present disclosure (5) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (4), wherein the concentration of hydrogen fluoride in the fluorine-containing gas composition is 50 ppm by volume or less.

[0014] The present disclosure (6) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (4), wherein the concentration of hydrogen fluoride in the fluorine-containing gas composition is 10 ppm by volume or less.

[0015] The present disclosure (7) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (6), wherein the Cr concentration in the fluorine-containing gas composition is 10 ppb by mass or less.

[0016] The present disclosure (8) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (7), wherein the concentration of the fluorine-containing molecules in the fluorine-containing gas composition is 99.9% by volume or more.

[0017] The present disclosure (9) relates to the method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (8), wherein the crude fluorine-containing gas composition contains 0.1 to 40% by volume of the fluorine-containing gas composition, with the remainder being an inert gas.

[0018] The present disclosure (10) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (8), wherein the crude fluorine-containing gas composition consists solely of the fluorine-containing gas composition.

[0019] The present disclosure (11) relates to a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (10), wherein the metal fluoride is at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides.

[0020] The present disclosure (12) relates to the method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (11), wherein the metal fluoride is filled in a metal fluoride-filled section.

[0021] The present disclosure (13) relates to the method for producing a purified fluorine-containing gas composition according to the present disclosure (12), wherein the metal fluoride-filled section is installed in an etching apparatus.

[0022] The present disclosure (14) relates to a method for producing a semiconductor device, comprising: a step of obtaining a purified fluorine-containing gas composition by applying the method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (13); and a step of etching a semiconductor element using the purified fluorine-containing gas composition.

[0023] The present disclosure (15) relates to a method for producing a semiconductor device, comprising: a step of obtaining a purified fluorine-containing gas composition by applying the method for producing a purified fluorine-containing gas composition according to the present disclosure (12) or (13); and a step of supplying the purified fluorine-containing gas composition, which is the outlet gas of the metal fluoride-filled section, to an etching chamber to etch a semiconductor element.

[0024] The present disclosure (16) relates to an etching apparatus having: a metal fluoride-filled section that brings a crude fluorine-containing gas composition, including a fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and having a Cr concentration of 100 ppb by mass or less, into contact with a solid metal fluoride at 30°C or less; and an etching chamber to which an outlet gas of the metal fluoride-filled section is supplied.

[0025] The method for producing a purified fluorine-containing gas composition according to the present disclosure comprises a contacting step of contacting a crude fluorine-containing gas composition containing a fluorine-containing gas composition having a content of 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a Cr concentration of 100 ppb by mass or less with a solid metal fluoride at 30° C. or less. Because the crude fluorine-containing gas composition containing a fluorine-containing gas composition having a content of 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a Cr concentration of 100 ppb by mass or less is contacted with a solid metal fluoride at 30° C. or less, a purified fluorine-containing gas composition can be produced that can suppress Cr from being mixed into the treated surface when etching is performed.

[0026] The method for producing a semiconductor device according to the present disclosure comprises the steps of obtaining a purified fluorine-containing gas composition by applying the method for producing a purified fluorine-containing gas composition according to the present disclosure, and etching a semiconductor element using the purified fluorine-containing gas composition. Since the method for producing a semiconductor device according to the present disclosure includes the step of etching a semiconductor element using the purified fluorine-containing gas composition obtained by applying the method for producing a purified fluorine-containing gas composition according to the present disclosure, incorporation of Cr into the semiconductor element is suppressed, and high-quality semiconductor devices can be produced.

[0027] The etching apparatus of the present disclosure is an etching apparatus having a metal fluoride-filled section that brings a crude fluorine-containing gas composition containing a fluorine-containing gas composition that contains 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and has a Cr concentration of 100 ppb by mass or less into contact with a solid metal fluoride at 30° C. or less, and an etching chamber to which an outlet gas of the metal fluoride-filled section is supplied. In the metal fluoride-filled section, the crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and having a Cr concentration of 100 ppb by mass or less is brought into contact with a solid metal fluoride at 30° C. or less, and the outlet gas is supplied to the etching chamber, so that it is possible to suppress Cr from being mixed into the surface to be treated when etching is performed.

[0028] Fig. 1 is a conceptual diagram showing an example of an embodiment of the present disclosure. Fig. 2 is a schematic diagram showing an example of an aluminum reactor. Fig. 3 is a schematic diagram showing an example of piping. Fig. 4 is a graph showing the results of Examples and Comparative Examples.

[0029] The present disclosure will be described in detail below, but the following description of the constituent elements is an example of an embodiment of the present disclosure, and the present disclosure is not limited to these specific details. Various modifications can be made within the scope of the gist of the present disclosure.

[0030] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0031] The method for producing a purified fluorine-containing gas composition according to the present disclosure comprises a contacting step of contacting a crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a fluorine-containing gas composition having a Cr concentration of 100 ppb by mass or less with a solid metal fluoride at 30° C. or less. Because the crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a fluorine-containing gas composition having a Cr concentration of 100 ppb by mass or less is contacted with a solid metal fluoride at 30° C. or less, a purified fluorine-containing gas composition can be produced that can suppress the incorporation of Cr into the surface to be treated during etching. The purified fluorine-containing gas composition can be used in applications such as etching to accommodate miniaturization in the semiconductor field.

[0032] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that the following mechanism is involved.

[0033] In the method described in Patent Document 1, since the content of metal components contained in the fluorine-containing gas composition before treatment is relatively high, it is presumed that in order to remove the metal components, the hydrogen fluoride concentration in the fluorine-containing gas composition needs to be 50 volume ppm or more. Even in the method described in Patent Document 1, the Cr concentration in the purified fluorine-containing gas composition obtained by the method described in Patent Document 1 is less than 5 mass ppb, which is the quantitation limit. As mentioned above, the present inventors believed that the method described in Patent Document 1 sufficiently removed metal components such as Cr. However, when etching was actually performed using the purified fluorine-containing gas composition obtained by the method described in Patent Document 1, it was found that there was room for improvement in terms of suppressing Cr contamination on the treated surface. This is presumed to be because, in the method described in Patent Document 1, the Cr concentration in the fluorine-containing gas composition before treatment is relatively high, and even if the Cr concentration in the purified fluorine-containing gas composition after treatment is below the quantitation limit, a certain amount of Cr remains.

[0034] On the other hand, in the present disclosure, a fluorine-containing gas composition having a higher purity than conventional ones, specifically a crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and having a Cr concentration of 100 ppb by mass or less, is contacted with a solid metal fluoride at 30° C. or less, thereby allowing metal components such as Cr to be adsorbed onto the metal fluoride and removed from the fluorine-containing gas composition, thereby producing a purified fluorine-containing gas composition with a higher purity than conventional techniques. Although a clear understanding is difficult due to the existence of a quantitation limit for the Cr concentration, when etching was performed using the purified fluorine-containing gas composition, the fact that Cr contamination on the treated surface was suppressed strongly suggests that the purified fluorine-containing gas composition obtained by the method for producing a purified fluorine-containing gas composition of the present disclosure is a purified fluorine-containing gas composition with a higher degree of purity than conventional ones.

[0035] Furthermore, since etching is performed using a purified fluorine-containing gas composition with a higher level of purification than conventional methods, it is presumed that it will be possible to suppress the incorporation of Cr into the treated surface during etching.

[0036] By using the purified fluorine-containing gas composition obtained by the method for producing a purified fluorine-containing gas composition according to the present disclosure, it is possible to suppress the incorporation of Cr into the surface to be treated. Therefore, the content of Cr atoms on the surface to be treated after etching is preferably 4.0 × 10 ９ atoms / cm ２ or less, more preferably 1.0 × 10 ９ atoms / cm ２ More preferably, 5.0 × 10 ８ atoms / cm ２ The lower limit is not particularly limited, but for example, 1.0 × 10 ５ atoms / cm ２ That's all. Metal contamination such as Cr on the substrate surface can cause unexpected fluctuations in conductivity, which can lead to loss of reliability in semiconductor devices, so this can improve the reliability of the device. In this specification, the content of each atom on the treated surface is measured by the method described in the Examples. In this specification, atoms / cm ２means the density of the number of certain atoms (for example, Cr atoms) present on a surface.

[0037] The object to be etched using the purified fluorine-containing gas composition obtained by the method for producing a purified fluorine-containing gas composition of the present disclosure is not particularly limited, and examples thereof include, but are not limited to, silicon wafers. ２ , SiN, AlO ｘ , HfO ｘ , ZrO ｘ , TiN, TaN, Ti, Co, Ru, Ta, W, and the like.

[0038] <Fluorine-containing gas composition> The fluorine-containing gas composition contains 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride, and has a Cr concentration of 100 ppb by mass or less. The fluorine-containing gas composition can be obtained by removing impurities in advance by distillation, cryogenic purification, contact with a solid metal fluoride, etc. For example, the fluorine-containing gas composition after purification obtained by the method described in Patent Document 1 may be used as the fluorine-containing gas composition.

[0039] The Cr concentration in the fluorine-containing gas composition is 100 mass ppb or less, preferably 90 mass ppb or less, more preferably 80 mass ppb or less, even more preferably 50 mass ppb or less, particularly preferably 30 mass ppb or less, most preferably 10 mass ppb or less, and most preferably less than 5 mass ppb, and the lower limit is not particularly limited, but is, for example, 0.1 mass ppb or more. This can further suppress the incorporation of Cr into the treated surface when etching is performed. Here, the Cr concentration in the fluorine-containing gas composition means the content ratio of Cr in 100 mass% of the fluorine-containing gas composition. The same applies to other similar descriptions.

[0040] The concentrations of metal components other than Cr (for example, Fe, Mn, Co, Ti, Mo, Cu, and Ni) in the fluorine-containing gas composition are preferably the same as the Cr concentration.

[0041] In this specification, the Cr concentration in a fluorine-containing gas composition is measured by an inductively coupled plasma mass spectrometer (ICP-MS). Metal components other than Cr are also measured by the same method. Here, metal components such as Cr are contained in the gas as fine particles or clusters of metals or metal compounds, or as gases of metal halides or metal complexes having relatively high vapor pressures. However, the concentration of each metal component is evaluated as the concentration converted to simple metal, not as the concentration of a metal compound or metal complex.

[0042] Metal components such as Cr are mixed into the fluorine-containing gas composition in the form of the above-mentioned metal impurities, for example, when metals used as materials for components such as reactors or piping in the production process of the fluorine-containing gas composition, or for cylinders, are corroded by the fluorine-containing gas composition. The content can be kept to 1,000 ppb by mass or less by using the above-mentioned corrosion-resistant metals for the components and cylinders, etc., but when the Cr concentration in the fluorine-containing gas composition exceeds 100 ppb by mass, the metal components such as Cr can be appropriately removed by known means, for example, by contacting the composition with a solid metal fluoride.

[0043] The hydrogen fluoride concentration in the fluorine-containing gas composition is preferably less than 50 volume ppm, preferably 40 volume ppm or less, more preferably 30 volume ppm or less, particularly preferably 20 volume ppm or less, most preferably 10 volume ppm or less, and most preferably 5 volume ppm or less. The lower limit is not particularly limited, but is preferably 0.01 volume ppm or more, more preferably 0.1 volume ppm or more, and may be more than 10 volume ppm. This can further suppress the incorporation of metal components such as Cr into the treated surface when etching is performed. Here, the hydrogen fluoride concentration in the fluorine-containing gas composition means the content ratio of hydrogen fluoride in 100 volume% of the fluorine-containing gas composition. In this specification, the hydrogen fluoride concentration in the fluorine-containing gas composition is measured by infrared spectroscopy.

[0044] Fluorine-containing molecules other than hydrogen fluoride include F ２ ClF, ClF ３ , IF ５ , IF ７ , BrF ３ , BrF５ , N.F. ３ , W.F. ６ , SiF ４ , C.F. ４ , S.F. ６ , B.F. ３ These may be used alone or in combination of two or more. ２ , ClF ３ , IF ７ , N.F. ３ , W.F. ６ , SiF ４ , C.F. ４ is preferred, and F ２ is more preferred.

[0045] The concentration of "fluorine-containing molecules other than hydrogen fluoride" in the fluorine-containing gas composition is 98% by volume or more, preferably 99% by volume or more, more preferably 99.9% by volume or more, and even more preferably 99.99% by volume or more. The upper limit is not particularly limited, but is, for example, 99.99999% by volume or less. This makes it possible to further suppress the incorporation of metal components such as Cr into the treated surface when etching is performed. Here, the concentration of "fluorine-containing molecules other than hydrogen fluoride" in the fluorine-containing gas composition means the content ratio of "fluorine-containing molecules other than hydrogen fluoride" in 100% of the fluorine-containing gas composition. When multiple fluorine-containing molecules are used, the concentration of fluorine-containing molecules means the total concentration of fluorine-containing molecules. The same applies to other similar descriptions. In this specification, the concentration of fluorine-containing molecules in the fluorine-containing gas composition is determined by dividing (subtracting) the concentration of components other than fluorine-containing molecules from 100% by volume.

[0046] <Crude Fluorine-Containing Gas Composition> The crude fluorine-containing gas composition is not particularly limited as long as it contains a fluorine-containing gas composition, and the crude fluorine-containing gas composition may consist solely of the fluorine-containing gas composition. That is, the concentration of the fluorine-containing gas composition in the crude fluorine-containing gas composition may be 100% by volume.

[0047] The crude fluorine-containing gas composition may contain components other than the fluorine-containing gas composition. The components other than the fluorine-containing gas composition are not particularly limited, but an inert gas is preferred. That is, the crude fluorine-containing gas composition preferably consists of the fluorine-containing gas composition and an inert gas.

[0048] The inert gas is N ２ , Ar, He, Ne, Kr, Xe, etc. These may be used alone or in combination of two or more. ２ , Ar are preferred.

[0049] The crude fluorine-containing gas composition preferably contains 0.1 to 40% by volume of the fluorine-containing gas composition, with the remainder being an inert gas, more preferably contains 0.1 to 20% by volume of the fluorine-containing gas composition, with the remainder being an inert gas, and even more preferably contains 0.5 to 20% by volume of the fluorine-containing gas composition, with the remainder being an inert gas.

[0050] The Cr concentration in the crude fluorine-containing gas composition is 100 mass ppb or less, preferably 90 mass ppb or less, more preferably 80 mass ppb or less, even more preferably 50 mass ppb or less, particularly preferably 30 mass ppb or less, most preferably 10 mass ppb or less, and most preferably less than 5 mass ppb, and the lower limit is not particularly limited, but is, for example, 0.1 mass ppb or more. This makes it possible to further suppress the incorporation of Cr into the treated surface when etching is performed. Here, the Cr concentration in the crude fluorine-containing gas composition means the Cr content in 100 mass% of the crude fluorine-containing gas composition. The same applies to other similar descriptions.

[0051] The concentrations of metal components other than Cr (for example, Fe, Mn, Co, Ti, Mo, Cu, and Ni) in the crude fluorine-containing gas composition are preferably similar to the Cr concentration.

[0052] The hydrogen fluoride concentration in the crude fluorine-containing gas composition is preferably less than 50 ppm by volume, preferably 40 ppm by volume or less, more preferably 30 ppm by volume or less, particularly preferably 20 ppm by volume or less, most preferably 10 ppm by volume or less, and most preferably 5 ppm by volume or less. The lower limit is not particularly limited, but is preferably 0.01 ppm by volume or more, more preferably 0.1 ppm by volume or more, and may be more than 10 ppm by volume. This makes it possible to further suppress the incorporation of metal components such as Cr into the treated surface when etching is performed. Here, the hydrogen fluoride concentration in the crude fluorine-containing gas composition means the content ratio of hydrogen fluoride in 100% by volume of the crude fluorine-containing gas composition. In this specification, the hydrogen fluoride concentration in the crude fluorine-containing gas composition is measured by infrared spectroscopy.

[0053] <Purified Fluorine-Containing Gas Composition> The concentrations of each component in the purified fluorine-containing gas composition obtained by the method for producing a purified fluorine-containing gas composition of the present disclosure may be difficult to measure due to the problem of quantitation limits, but for reasons that allow for more suitable use in the production process of semiconductor devices, they are, for example, as follows: The Cr concentration in the purified fluorine-containing gas composition is preferably less than 5 ppb by mass, and the lower limit is not particularly limited, but is, for example, 0.1 ppb by mass or more. The hydrogen fluoride concentration in the purified fluorine-containing gas composition is preferably 10 ppm by volume or less, and the lower limit is not particularly limited, but is, for example, 0.01 ppm by volume or more. The concentration of "fluorine-containing molecules other than hydrogen fluoride" in the purified fluorine-containing gas composition is preferably 99.99% by volume or more, and the upper limit is not particularly limited, but is, for example, 99.99999% by volume or less.

[0054] <Purification Apparatus 10> The purification apparatus 10 according to the present disclosure is supplied with a fluorine-containing gas composition from a crude fluorine-containing gas composition supply section 20, and supplies an outlet gas to an external device 30. The purification apparatus 10 includes at least a metal fluoride filling section 100. If necessary, the purification apparatus may also include a hydrogen fluoride supply section that supplies hydrogen fluoride to the crude fluorine-containing gas composition supply section 20. If necessary, the purification apparatus may also include an inert gas supply section that supplies an inert gas to the crude fluorine-containing gas composition supply section 20.

[0055] <Metal Fluoride-Filled Section 100> The metal fluoride is preferably filled in the metal fluoride-filled section. The metal fluoride-filled section 100 is a container filled with a chemical containing a metal fluoride and is designed appropriately depending on the purity and flow rate of the gas passing through. For example, a decontamination system can be used in which metal fluoride pellets are filled on a bottom mesh, the gas to be treated is introduced from the bottom, and the gas is discharged from the top. The chemical to be filled may be in the form of a powder, granules, or pellets as long as it contains a metal fluoride. The purity of the metal fluoride is not particularly limited, but is typically 90% by mass or higher, preferably 95% by mass or higher. Examples of metal fluorides that can be used include alkali metal fluorides and alkaline earth metal fluorides. These may be used alone or in combination of two or more. Specific examples of metal fluorides include lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, and barium fluoride. These metal fluorides are preferred because they have low reactivity with fluorine compounds but can adsorb hydrogen fluoride gas. Of these, sodium fluoride is more preferred.

[0056] Furthermore, the material used for the container of the metal fluoride filling unit 100 is a metal that is corrosion-resistant to fluorine compounds, fluorine, and hydrogen fluoride. Specifically, nickel, nickel-based alloys such as Hastelloy (registered trademark), Monel (registered trademark), or Inconel (registered trademark), aluminum, aluminum alloys, or stainless steel can be selected. These may be used alone or in combination of two or more. Of these, nickel is preferred. Regarding stainless steel, the Fe and Cr contained in the material may react with the fluorine compounds, potentially becoming a source of metal impurities. Therefore, prior to use, the stainless steel must be treated by passing a fluorine compound gas or fluorine gas through the material to form a passivation film on the surface.

[0057] Furthermore, the operating temperature of metal fluoride-packed section 100, i.e., the temperature at which the crude fluorine-containing gas composition is brought into contact with the solid metal fluoride (the temperature of the solid metal fluoride), is 30° C. or lower. Since a better purification effect can be obtained by using metal fluoride-packed section 100 at as low a temperature as possible, the temperature is preferably below 0° C., more preferably below −10° C., even more preferably below −20° C., particularly preferably below −30° C., and most preferably below −40° C., and the lower limit is not particularly limited, but is, for example, above −80° C. By setting the temperature of the solid metal fluoride to below 0° C., metal components such as Cr tend to be able to be suitably removed even from a fluorine-containing gas composition having a hydrogen fluoride concentration of less than 50 ppm by volume.

[0058] The amount of the metal fluoride filled in the metal fluoride-filled section is, for example, 5 kg or less, 1 kg or less, or 0.2 kg or less. The lower limit is not particularly limited as long as sufficient adsorption capacity is maintained, but it is, for example, 1 g or more or 5 g or more. In the present disclosure, a purified fluorine-containing gas composition can be suitably produced without using large facilities such as gas production facilities.

[0059] The volume of the metal fluoride filling section is, for example, 5 L or less, 1 L or less, or 0.2 L or less. As long as there is sufficient adsorption capacity, the lower limit is not particularly limited. For example, ３ More than 5cm ３ According to the present disclosure, a purified fluorine-containing gas composition can be suitably produced without using large facilities such as gas production facilities.

[0060] The fluorine-containing gas composition supplied to the metal fluoride-packed section 100 is as described above. Similarly, the purified fluorine-containing gas composition that is the outlet gas of the metal fluoride-packed section 100 is as described above.

[0061] <Crude fluorine-containing gas composition supply section 20> The crude fluorine-containing gas composition supply section 20 is a storage section for a crude fluorine-containing gas composition produced in a fluorine-containing gas composition production facility, a cylinder filled with the crude fluorine-containing gas composition, or the like. By supplying the crude fluorine-containing gas composition from the crude fluorine-containing gas composition supply section 20 to the metal fluoride filling section 100, it becomes possible to carry out a contact step in which the crude fluorine-containing gas composition is brought into contact with a solid metal fluoride. Then, a purified fluorine-containing gas composition is obtained as the outlet gas of the metal fluoride filling section 100. If necessary, an inert gas supply section for supplying an inert gas to the crude fluorine-containing gas composition supply section 20 may be provided, and the crude fluorine-containing gas composition may be diluted before supply. Examples of such a case include supplying a crude fluorine-containing gas composition having a fluorine-containing gas composition concentration of 100% by volume from a cylinder filled with the fluorine-containing gas composition, supplying a crude fluorine-containing gas composition containing 0.1 to 40% by volume of the fluorine-containing gas composition from a cylinder filled with an inert gas and the fluorine-containing gas composition, and supplying a crude fluorine-containing gas composition containing 0.1 to 40% by volume of the fluorine-containing gas composition by mixing gases from both a cylinder filled with the fluorine-containing gas composition and a cylinder filled with a diluent gas.

[0062] <External Device 30> An external device 30 is connected downstream of the refining device 10. For example, when the method of the present disclosure is used in a process for producing a fluorine-containing gas composition, the external device 30 corresponds to a filling facility for the fluorine-containing gas composition. Furthermore, when the method of the present disclosure is used in a process for producing a semiconductor device, such as a gas supply line for an etching process, the etching device corresponds to the external device 30. Note that both the refining device 10 and the external device 30 may be provided in a single housing. For example, by providing the refining device of the present disclosure at the gas inlet or midway through the piping of the etching device and supplying the outlet gas of the refining device (metal fluoride filling section) to the etching chamber, a semiconductor element can be etched using a purified fluorine-containing gas composition from which metal components have been removed, thereby producing a semiconductor device. Here, in order to suppress the intrusion of metal components such as Cr from the piping, the piping is preferably made of nickel.

[0063] It is preferable that a metal fluoride-filled section is installed in the etching apparatus, and more preferably, the metal fluoride-filled section is provided at the gas inlet of the etching apparatus or in the middle of the piping that supplies gas to the etching chamber so that the purified fluorine-containing gas composition, which is the outlet gas of the metal fluoride-filled section, can be supplied to the etching chamber. That is, it is preferable that the purified fluorine-containing gas composition, which is the outlet gas of the metal fluoride-filled section, is supplied to the etching chamber to etch a semiconductor element. This makes it possible to more effectively prevent metal components from piping from mixing into the purified fluorine-containing gas composition, thereby enabling the production of higher quality semiconductor devices. An etching apparatus that can be suitably used in this process is preferably an etching apparatus having a metal fluoride-filled section that brings a crude fluorine-containing gas composition, which contains 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a fluorine-containing gas composition having a Cr concentration of 100 ppb by mass or less, into contact with a solid metal fluoride at 30° C. or less, and an etching chamber to which the outlet gas of the metal fluoride-filled section is supplied.

[0064] <Effects of the Purification Apparatus 10> The purification apparatus 10 utilizing the present disclosure is a device with a simple structure that is simply filled with a chemical agent, and is capable of reducing the Cr concentration to a very low level. Therefore, even small-scale factories can utilize the present disclosure to obtain gas with low metal impurities (Cr). Furthermore, since the purification apparatus 10 can be installed immediately before the use of the fluorine-containing gas composition, it is possible to prevent the inclusion of metal components derived from piping, etc., and the external device 30 can utilize gas with low metal impurities.

[0065] Examples of the present disclosure will be listed below along with comparative examples, but the present disclosure is not limited to the following examples.

[0066] Example 1 An 8-inch silicon wafer 202 having a silicon oxide film (film thickness: 100 nm) formed on its surface was placed in an aluminum reactor 200 shown in FIG. 2. A fluorine-containing gas composition (Cr concentration: less than 5 mass ppb, which is the limit of quantification; hydrogen fluoride concentration: 38 volume ppm; F concentration calculated from the contents of other components) was placed around the aluminum reactor 200, as shown in the piping diagram in FIG. 3. ２A fluorine-containing gas composition supply part (concentration: 99.9% by volume or more, with other metal components (Fe, Mn, Co, Ti, Mo, Cu, Ni) concentrations also being less than 5 ppb by mass, which is the limit of quantification), a nitrogen gas (100% nitrogen gas) supply part, and a dry pump were connected to the reactor, so that the fluorine-containing gas composition and nitrogen gas could be circulated and a vacuum could be created. In addition, a gas purification filter (½-inch nickel piping filled with about 7 g of sodium fluoride) was installed between the fluorine-containing gas composition supply part and the nitrogen gas supply part and the aluminum reactor 200.

[0067] First, the lid 201 of the aluminum reactor 200 was closed, and the inside of the aluminum reactor 200 was evacuated to a vacuum state. Then, the fluorine-containing gas composition was passed through a gas purification filter cooled to −40° C. using a mass flow controller to flow 20 cm ３ The aluminum reactor 200 was then evacuated and nitrogen gas was introduced at a flow rate of 100 cm3 / min to the wafer for 1 minute. ３ After flowing the gas at a flow rate of 10 minutes at 1 / min, the wafer was removed. The silicon oxide film on the removed wafer was then etched with dilute hydrofluoric acid to recover the metal components adhering to the wafer. The sample was analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) to determine the Cr atom content (atoms / cm) on the wafer. ２ The results are shown in Table 1 and FIG.

[0068] Example 2 A test was carried out under the same conditions as in Example 1, except that the temperature of the gas purification filter was set to -1°C.

[0069] [Example 3] A test was carried out under the same conditions as in Example 1, except that the temperature of the gas purification filter was set to 20°C.

[0070] Comparative Example 1 A test was carried out under the same conditions as in Example 1, except that the gas purification filter was omitted.

[0071]

[0072] From Table 1 and FIG. 4, in Comparative Example 1 in which a gas purification filter was not installed, the Cr concentration on the wafer was 4.8×10 ９ atoms / cm ２However, in Examples 1 and 2 in which a gas purification filter was installed and cooling was performed, the Cr concentration on the wafer was significantly reduced compared to Comparative Example 1. Furthermore, even at 20°C, the Cr concentration on the wafer was reduced compared to Comparative Example 1. Therefore, it was found that a purified fluorine-containing gas composition that can suppress Cr contamination onto the treated surface when etching is performed can be produced by contacting a crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and a fluorine-containing gas composition having a Cr concentration of 100 mass ppb or less with a solid metal fluoride at 30°C or less. In particular, it was found that by setting the temperature of the solid metal fluoride to less than 0°C, the effect of suppressing Cr contamination is dramatically improved, and it is possible to more suitably suppress Cr contamination onto the treated surface.

[0073] REFERENCE SIGNS LIST 10 Purification device 20 Crude fluorine-containing gas composition supply section 30 External device 100 Metal fluoride filling section 200 Aluminum reactor 201 Lid 202 Silicon wafer

Claims

1. A method for producing a purified fluorine-containing gas composition, comprising a contacting step of contacting a crude fluorine-containing gas composition, the crude fluorine-containing gas composition including a fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and having a Cr concentration of 100 ppb by mass or less, with a solid metal fluoride at 30°C or less.

2. A method for producing a purified fluorine-containing gas composition according to claim 1, wherein in said contacting step, said crude fluorine-containing gas composition is contacted with a solid metal fluoride at a temperature below 0°C.

3. A method for producing a purified fluorine-containing gas composition according to claim 1, wherein in said contacting step, said crude fluorine-containing gas composition is contacted with a solid metal fluoride at -20°C or lower.

4. The fluorine-containing molecule is F ２ , ClF, ClF ３ , I.F. ５ , I.F. ７ , BrF ３ , BrF ５ , N.F. ３ , W.F. ６ , SiF ４ , C.F. ４ , S.F. ６ , and BF ３ 3. The method for producing a purified fluorine-containing gas composition according to claim 1, wherein the compound is at least one selected from the group consisting of:

5. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the concentration of hydrogen fluoride in said fluorine-containing gas composition is 50 ppm by volume or less.

6. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the concentration of hydrogen fluoride in said fluorine-containing gas composition is 10 ppm by volume or less.

7. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the Cr concentration in said fluorine-containing gas composition is 10 ppb by mass or less.

8. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the concentration of said fluorine-containing molecules in said fluorine-containing gas composition is 99.9 volume % or more.

9. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein said crude fluorine-containing gas composition contains 0.1 to 40% by volume of said fluorine-containing gas composition, the remainder being an inert gas.

10. A method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein said crude fluorine-containing gas composition consists solely of said fluorine-containing gas composition.

11. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the metal fluoride is at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides.

12. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the metal fluoride is packed in a metal fluoride-packed section.

13. The method for producing a purified fluorine-containing gas composition according to claim 12, wherein the metal fluoride-filled section is installed inside an etching device.

14. A method for producing a semiconductor device, comprising the steps of: obtaining a purified fluorine-containing gas composition by applying the method for producing a purified fluorine-containing gas composition according to claim 1 or 2; and etching a semiconductor element using the purified fluorine-containing gas composition.

15. A method for producing a semiconductor device, comprising the steps of: obtaining a purified fluorine-containing gas composition by applying the method for producing a purified fluorine-containing gas composition as defined in claim 12; and supplying the purified fluorine-containing gas composition, which is the outlet gas of the metal fluoride-filled section, to an etching chamber to etch a semiconductor element.

16. An etching apparatus comprising: a metal fluoride-filled section for contacting a crude fluorine-containing gas composition, the crude fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and having a Cr concentration of 100 ppb by mass or less, with a solid metal fluoride at 30°C or less; and an etching chamber to which an outlet gas of the metal fluoride-filled section is supplied.

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