WO2025041699A1 - Method for producing purified fluorine-containing gas composition, method for producing semiconductor device, and etching apparatus - Google Patents

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

This disclosure relates to a method for producing a purified fluorine-containing gas composition, a method for producing a semiconductor device that applies the method for producing the purified fluorine-containing gas composition, and an etching apparatus.

Fluorine gas and other fluorine-containing gas compositions are widely used as gases for etching substrates or cleaning thin-film formation equipment such as CVD (Chemical Vapor Deposition) in the manufacturing processes of semiconductor devices, MEMS (Micro Electro Mechanical Systems) devices, liquid crystal TFT (Thin Film Transistor) panels, and solar cells, or as fluorinating agents for the synthesis of fluorine chemicals.

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. In this situation, there is concern that impurities contained in the materials of semiconductor devices may cause problems in the manufacturing process of semiconductor devices, such as reducing product yields. Therefore, there is a demand for high purity fluorine gas to be used, and the required level is particularly high, with metal impurities, which have a large impact on electrical properties, needing to be reduced to less than 10 ppb by mass.

For example, Patent Document 1 discloses that when the hydrogen fluoride concentration 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 solid metal fluorides and removed together with the hydrogen fluoride, thereby purifying the fluorine gas.

JP 2017-141149 A

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.

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 treated surface when etching is performed, a method for producing a semiconductor device that applies the method for producing a purified fluorine-containing gas composition, and an etching apparatus.

As a result of extensive research, the present inventors discovered that even a fluorine-containing gas composition with a very low Cr concentration can be made into a purified fluorine-containing gas composition with a higher purity by contacting it with a solid metal fluoride at 30°C or lower, 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, thus completing the present disclosure.

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, which includes 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.

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

The present disclosure (3) relates to a method for producing a purified fluorine-containing gas composition according to the present disclosure (1), in which the crude fluorine-containing gas composition is contacted with a solid metal fluoride at -20°C or lower in the contacting step.

The present disclosure (4) relates to a method for producing a purified _fluorine -containing gas composition according to any _one of _the present disclosures (1) to (3), wherein the fluorine-containing molecule is at least one selected from _the group consisting of _F2 , ClF, ClF3, _IF5 , _IF7 , _BrF3 , _BrF5 , _NF3 , _WF6 , _SiF4 , CF4, SF6, and BF3.

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), in which the hydrogen fluoride concentration in the fluorine-containing gas composition is 50 ppm by volume or less.

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), in which the hydrogen fluoride concentration in the fluorine-containing gas composition is 10 ppm by volume or less.

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), in which the Cr concentration in the fluorine-containing gas composition is 10 ppb by mass or less.

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), in which the concentration of the fluorine-containing molecules in the fluorine-containing gas composition is 99.9% by volume or more.

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

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), in which the crude fluorine-containing gas composition consists solely of the fluorine-containing gas composition.

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), in which the metal fluoride is at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides.

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

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

The present disclosure (14) provides a method for producing a purified fluorine-containing gas composition according to any one of the present disclosures (1) to (13), comprising the steps of: obtaining a purified fluorine-containing gas composition;
Etching a semiconductor device using the purified fluorine-containing gas composition;
The present invention relates to a method for manufacturing a semiconductor device, comprising:

The present disclosure (15) provides a method for producing a purified fluorine-containing gas composition according to the present disclosure (12) or (13), comprising the steps of: obtaining a purified fluorine-containing gas composition;
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 device;
The present invention relates to a method for manufacturing a semiconductor device, comprising:

The present disclosure (16) relates to a method for producing 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, contacting the crude fluorine-containing gas composition with a solid metal fluoride at 30° C. or less;
an etching chamber to which the outlet gas of the metal fluoride filling section is supplied;
The present invention relates to an etching apparatus having the above structure.

The method for producing a purified fluorine-containing gas composition disclosed herein includes 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 treated surface when etching is performed.

The method for producing a semiconductor device according to the present disclosure includes 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 steps 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, the incorporation of Cr into the semiconductor element is suppressed, and a high-quality semiconductor device can be produced.

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 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 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. In the metal fluoride-filled section, 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 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 the incorporation of Cr into the surface to be treated when etching is performed.

FIG. 1 is a conceptual diagram illustrating 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 the examples and the comparative examples.

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

In this specification, the notation "X to Y" in the explanation of a numerical range means from X to Y, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass to 5% by mass."

The method for producing a purified fluorine-containing gas composition disclosed herein includes 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. Since 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 treated surface when etching is performed. The purified fluorine-containing gas composition can be used for applications such as etching that corresponds to miniaturization in the semiconductor field.

The reason why the above-mentioned effect is obtained is not entirely clear, but it is presumed to be due to the following mechanism.

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 must be 50 ppm by volume or more. 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 ppb by mass, which is the quantification limit. As described above, the present inventors believed that the method described in Patent Document 1 sufficiently removed metal components such as Cr, but 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 the incorporation of Cr into the treated surface. This is because, in the method described in Patent Document 1, the Cr concentration in the fluorine-containing gas composition before treatment is relatively high, and it is presumed that a certain amount of Cr remains even if the Cr concentration in the purified fluorine-containing gas composition after treatment is below the quantification limit.

On the other hand, in the present disclosure, a crude fluorine-containing gas composition having a higher purity than the conventional one, 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, so that metal components such as Cr can 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 the conventional technology. Although it is difficult to clearly grasp the Cr concentration because of the existence of a quantitative limit, when etching is performed using the purified fluorine-containing gas composition, the incorporation of Cr into the treated surface can be suppressed, which 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 the conventional one.

And because 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 intrusion of Cr onto the treated surface during etching.

By using the purified fluorine-containing gas composition obtained by the method for producing a purified fluorine-containing gas composition of the present disclosure, it is possible to suppress the incorporation of Cr into the treated surface.
Therefore, the content of Cr atoms on the treated surface after etching is preferably 4.0×10 ⁹ atoms/cm ² or less, more preferably 1.0×10 ⁹ atoms/cm ² or less, and even more preferably 5.0×10 ⁸ atoms/cm ² or less, and although there is no particular lower limit, it is, for example, 1.0×10 ⁵ atoms/cm ² or more. Metal contamination of the substrate surface with Cr or the like can cause unexpected fluctuations in electrical conductivity and may cause a loss of reliability of a semiconductor device, 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/ ^cm2 means the density of the number of certain atoms (e.g., Cr atoms) present on the surface.

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 typically includes, but is not limited to, silicon wafers. In addition to silicon wafers, examples of the object to be etched include semiconductor device substrates such as _SiO2 , SiN, _AlOx , _HfOx , _ZrOx , TiN, TaN, Ti, Co, Ru, Ta, and W.

<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 mass ppb or less. The fluorine-containing gas composition can be obtained by removing impurities in advance by distillation, cryogenic purification, contact with 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.

The Cr concentration in the fluorine-containing gas composition is 100 ppb by mass or less, preferably 90 ppb by mass or less, more preferably 80 ppb by mass or less, even more preferably 50 ppb by mass or less, particularly preferably 30 ppb by mass or less, most preferably 10 ppb by mass or less, and most preferably less than 5 ppb by mass, and the lower limit is not particularly limited, but is, for example, 0.1 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 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.

It is preferable that the concentration of each metal component other than Cr (e.g., Fe, Mn, Co, Ti, Mo, Cu, Ni) in the fluorine-containing gas composition is similar to the Cr concentration.

In this specification, the Cr concentration in the 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, the 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 a relatively high vapor pressure. However, the concentration of each metal component is evaluated as the concentration converted to a simple metal, not as the concentration of a metal compound or metal complex.

Metal components such as Cr are mixed into the fluorine-containing gas composition in the form of the aforementioned metal impurities, for example, when metals used as materials for components such as reactors or piping in the manufacturing process of the fluorine-containing gas composition, or for cylinders, are corroded by the fluorine-containing gas composition. The content can be kept to 1000 mass ppb or less by using the aforementioned corrosion-resistant metals for components and cylinders, but if the Cr concentration in the fluorine-containing gas composition exceeds 100 mass ppb, the metal components such as Cr can be appropriately removed using known means, for example, by contacting the composition with a solid metal fluoride.

The hydrogen fluoride concentration in the 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, and 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 fluorine-containing gas composition means the content ratio of hydrogen fluoride in 100% by 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.

Examples of fluorine-containing molecules other than hydrogen fluoride include _F2 ; fluorine compounds such as ClF, _ClF3 , _IF5 , _IF7 , _BrF3 , _BrF5 , _NF3 , _WF6 , _SiF4 , _CF4 , _SF6 , and _BF3 ; and the like. These may be used alone or in combination of two or more. Among them, _F2 , _ClF3 , _IF7 , _NF3 , _WF6 , _SiF4 , and _CF4 are preferred, and _F2 is more preferred.

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, and 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 a plurality of fluorine-containing molecules are used, the concentration of the fluorine-containing molecules means the total concentration of the fluorine-containing molecules. The same applies to other similar descriptions.
In this specification, the concentration of fluorine-containing molecules in a fluorine-containing gas composition is determined by dividing (subtracting) the concentration of components other than fluorine-containing molecules from 100 volume %.

<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 of only the fluorine-containing gas composition, i.e., the concentration of the fluorine-containing gas composition in the crude fluorine-containing gas composition may be 100% by volume.

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 a fluorine-containing gas composition and an inert gas.

Examples of the inert gas include _N2 , Ar, He, Ne, Kr, and Xe. These may be used alone or in combination of two or more. Among these, _N2 and Ar are preferred.

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.

The Cr concentration in the crude fluorine-containing gas composition is 100 ppb by mass or less, preferably 90 ppb by mass or less, more preferably 80 ppb by mass or less, even more preferably 50 ppb by mass or less, particularly preferably 30 ppb by mass or less, most preferably 10 ppb by mass or less, and most 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. 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 content ratio of Cr in 100 mass % of the crude fluorine-containing gas composition. The same applies to other similar descriptions.

It is preferable that the concentrations of each metal component other than Cr (e.g., Fe, Mn, Co, Ti, Mo, Cu, Ni) in the crude fluorine-containing gas composition be similar to the Cr concentration.

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, and 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.

<Refined 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 quantification limits, but because they can be more suitably used 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 although there is no particular lower limit, it 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 although there is no particular lower limit, it 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 although there is no particular upper limit, it is, for example, 99.99999% by volume or less.

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

<Metal fluoride filled section 100>
The metal fluoride is preferably filled in the metal fluoride filling section. The metal fluoride filling section 100 is a container filled with a chemical agent containing a metal fluoride, and is appropriately designed according to the purity and flow rate of the gas flowing through. For example, a decontamination device can be used in which metal fluoride pellets are filled on the bottom net, the gas to be treated is introduced from the bottom, and the gas is discharged from the top. The chemical agent to be filled may be in the form of a powder, a granule, or a pellet as long as it contains a metal fluoride, and the purity of the metal fluoride is not particularly limited, but is usually 90% by mass or more, and preferably 95% by mass or more. Examples of the metal fluoride to 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 the metal fluoride include lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, barium fluoride, and the like. These metal fluorides are preferred because they have low reactivity with fluorine compounds but can adsorb hydrogen fluoride gas. Among these, sodium fluoride is more preferred.

The material used for the container of the metal fluoride filling section 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 preferable. Note that, with regard to stainless steel, the Fe and Cr contained in the material react with the fluorine compounds, which may become a source of metal impurities, so it is necessary to pass a fluorine compound gas or fluorine gas through the material before use to perform a process such as forming a passivation film on the surface.

The operating temperature of the metal fluoride-filled 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 the metal fluoride-filled section 100 at the lowest possible temperature, the temperature is preferably less than 0°C, more preferably less than -10°C, even more preferably less than -20°C, particularly preferably less than -30°C, and most preferably less than -40°C, and the lower limit is not particularly limited, but is, for example, more than -80°C. By setting the temperature of the solid metal fluoride to less than 0°C, there is a tendency that metal components such as Cr can be suitably removed even from a fluorine-containing gas composition having a hydrogen fluoride concentration of less than 50 ppm by volume.

The amount of the metal fluoride filled in the metal fluoride filling section is, for example, 5 kg or less, 1 kg or less, or 0.2 kg or less. As long as there is sufficient adsorption capacity, the lower limit is not particularly limited, but 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 equipment such as a gas production facility.

The volume of the metal fluoride-filled 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, and is, for example, 1 ^cm3 or more, or 5 ^cm3 or more. In the present disclosure, a purified fluorine-containing gas composition can be suitably produced without using large equipment such as a gas production facility.

The fluorine-containing gas composition supplied to the metal fluoride filling section 100 is as described above. Similarly, the purified fluorine-containing gas composition which is the outlet gas of the metal fluoride filling section 100 is as described above.

<Crude fluorine-containing gas composition supply section 20>
The crude fluorine-containing gas composition supply section 20 is a storage section for the crude fluorine-containing gas composition produced in a production facility for a fluorine-containing gas composition, or a cylinder filled with the crude fluorine-containing gas composition. 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 the composition include a crude fluorine-containing gas composition having a concentration of 100% by volume from a cylinder filled with the fluorine-containing gas composition, a crude fluorine-containing gas composition containing 0.1 to 40% by volume of the fluorine-containing gas composition is supplied from a cylinder filled with an inert gas and the fluorine-containing gas composition, and a crude fluorine-containing gas composition containing 0.1 to 40% by volume of the fluorine-containing gas composition is supplied by mixing gases from both a cylinder filled with the fluorine-containing gas composition and a cylinder filled with a diluent gas.

<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 the manufacturing process of a fluorine-containing gas composition, the external device 30 corresponds to a filling facility for the fluorine-containing gas composition. Also, when the method of the present disclosure is used in the manufacturing process of a semiconductor device such as a gas supply line in an etching process, an etching device corresponds to the external device 30. Note that both the refining device 10 and the external device 30 may be provided in one housing. For example, the refining device of the present disclosure is provided in the gas inlet or midway of the piping of the etching device, and the outlet gas of the refining device (metal fluoride filling section) is supplied to the etching chamber, so that a semiconductor element can be etched using a purified fluorine-containing gas composition from which metal components have been removed, and a semiconductor device can be manufactured. Here, in order to suppress the intrusion of metal components such as Cr from the piping, the piping is preferably made of nickel.

It is preferable that a metal fluoride filling section is installed in the etching apparatus, and more preferably, the metal fluoride filling section is provided in 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 filling 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 filling section, is supplied to the etching chamber to etch the semiconductor element. This makes it possible to more suitably suppress the contamination of the purified fluorine-containing gas composition with metal components originating from the piping, etc., and to manufacture a higher quality semiconductor device. As an etching apparatus that can be suitably used for this process, an etching apparatus having a metal fluoride filling section that contacts 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, and an etching chamber to which the outlet gas of the metal fluoride filling section is supplied is preferable.

<Effects of the refining device 10>
The refining device 10 using 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 obtain gas with low metal impurities (Cr) using the present disclosure. In addition, since the refining device 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 use gas with low metal impurities.

Examples of the present disclosure are given below along with comparative examples, but the present disclosure is not limited to the following examples.

[Example 1]
An 8-inch silicon wafer 202 with a silicon oxide film (film thickness: 100 nm) formed on the surface was placed in an aluminum reactor 200 shown in FIG. 2. Around the aluminum reactor 200, as shown in the piping diagram in FIG. 3, a fluorine-containing gas composition (Cr concentration: less than 5 mass ppb which is the limit of quantification, hydrogen fluoride concentration: 38 volume ppm, _F2 concentration calculated from the contents of other components: 99.9 volume% or more, other metal components (Fe, Mn, Co, Ti, Mo, Cu, Ni) concentrations are also less than 5 mass ppb which is the limit of quantification) supply part, a nitrogen gas (100% nitrogen gas) supply part, and a dry pump are connected, so that the fluorine-containing gas composition and nitrogen gas can be circulated and a vacuum state can be created. In addition, a gas purification filter (1/2-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.

First, the lid 201 of the aluminum reactor 200 was closed, and the aluminum reactor 200 was degassed to a vacuum state, and then the fluorine-containing gas composition was passed through a gas purification filter cooled to -40°C using a mass flow controller to flow through the wafer at 20 cm ³ /min for 1 minute. Thereafter, the aluminum reactor 200 was degassed under vacuum, and nitrogen gas was passed through the wafer at 100 cm ³ /min for 10 minutes, and then the wafer was removed. Next, the silicon oxide film on the removed wafer was etched with dilute hydrofluoric acid to recover metal components attached to the wafer. The sample was analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) to measure the content (atoms/cm ² ) of Cr atoms on the wafer. The results are shown in Table 1 and FIG. 4.

[Example 2]
The 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.

[Example 3]
The 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.

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

From Table 1 and FIG. 4, in Comparative Example 1 where no gas purification filter was installed, the Cr concentration on the wafer was 4.8×10 ⁹ atoms/cm ² , but in Examples 1 and 2 where a gas purification filter was installed and cooled, the Cr concentration on the wafer was significantly lower than that of Comparative Example 1. In addition, even at 20° C., the Cr concentration on the wafer was lower than that of Comparative Example 1. Therefore, it was found that 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 can be produced by contacting a solid metal fluoride at 30° C. or less with the crude fluorine-containing gas composition, which contains a fluorine-containing gas composition containing 98% by volume or more of fluorine-containing molecules other than hydrogen fluoride and has a Cr concentration of 100 mass ppb or less, when etching is performed, with a solid metal fluoride at 30° C. or less. In particular, it was found that the effect of suppressing Cr contamination was dramatically improved by setting the temperature of the solid metal fluoride to less than 0° C., and it was found that it was possible to more suitably suppress Cr contamination on the surface to be treated.

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 (16)

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 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. The method for producing a purified fluorine-containing gas composition according to claim 1, wherein in the contacting step, the crude fluorine-containing gas composition is contacted with a solid metal fluoride at a temperature below 0°C. The method for producing a purified fluorine-containing gas composition according to claim 1, wherein in the contacting step, the crude fluorine-containing gas composition is contacted with a solid metal fluoride at -20°C or lower. 3. A method for producing a purified fluorine-containing gas composition according to claim 1 or ₂ , wherein the fluorine-containing molecule is at least one selected from the group consisting of _F2 , ClF, _ClF3 , _IF5 , _IF7 , _BrF3 , _BrF5 , _NF3 , _WF6 , _SiF4 , _CF4 , _SF6 , and BF3. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the hydrogen fluoride concentration in the fluorine-containing gas composition is 50 ppm by volume or less. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the hydrogen fluoride concentration in the fluorine-containing gas composition is 10 ppm by volume or less. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the Cr concentration in the fluorine-containing gas composition is 10 mass ppb or less. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the concentration of the fluorine-containing molecules in the fluorine-containing gas composition is 99.9% by volume or more. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the crude fluorine-containing gas composition contains 0.1 to 40 volume % of the fluorine-containing gas composition, with the remainder being an inert gas. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the crude fluorine-containing gas composition consists solely of the fluorine-containing gas composition. 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. The method for producing a purified fluorine-containing gas composition according to claim 1 or 2, wherein the metal fluoride is filled in a metal fluoride filling section. The method for producing a purified fluorine-containing gas composition according to claim 12, wherein the metal fluoride filling section is installed inside an etching device. A step 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;
Etching a semiconductor device using the purified fluorine-containing gas composition;
A method for manufacturing 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 claim 12;
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 device;
A method for manufacturing a semiconductor device, comprising: a metal fluoride-packed section for 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;
an etching chamber to which the outlet gas of the metal fluoride filling section is supplied;
An etching apparatus comprising:

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