JP7632086B2 - Method for producing fluorocarbons - Google Patents

Description

The present invention relates to a method for producing fluorohydrocarbons.

Fluorinated hydrocarbons, including monofluoromethane, are widely used for purposes such as etching gases for semiconductor microfabrication.

A known method for producing monofluoromethane involves reacting methyl chloride (CH ₃ Cl) with hydrogen fluoride in the gas phase in the presence of a fluorination catalyst to obtain a mixed gas containing monofluoromethane, and then separating and purifying the monofluoromethane from the mixed gas.

JP 2006-111611 A

However, the above-mentioned method for producing monofluoromethane requires a large amount of preparation of the fluorination catalyst, and the yield decreases as the activity of the catalyst decreases, making continuous production difficult.

The present invention aims to provide a method for producing fluorohydrocarbons, including monofluoromethane, simply and inexpensively using a gas-phase flow system without using a catalyst.

The present invention aims to advantageously solve the above-mentioned problems, and provides a method for producing a plasma device comprising the steps of: continuously supplying a raw material gas containing a compound represented by formula 1: CH ₃ -R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom or an organic group (excluding a hydrocarbon group)) and an inert gas to a thermal non-equilibrium region of a plasma device containing active species derived from a solid fluorine-containing inorganic compound;
and then continuously discharging the gas in the thermally non-equilibrium region to the outside of the plasma device.

Here, thermal non-equilibrium refers to a state in which the temperature of ions and molecules is different from the temperature of electrons, and in a thermal non-equilibrium region within a plasma device, the temperature of electrons is higher than the temperature of ions and molecules.
The discharge region in a plasma device is the space between opposing electrodes in a plasma device that generates plasma using electrodes, but in a method in which a flame is extracted outside the space between the electrodes, such as a plasma jet, it corresponds to the flame zone, and in a plasma device that generates plasma by means other than electrodes, it is the corresponding space.
The solid fluorine-containing inorganic compound refers to a fluorine-containing inorganic compound that is solid under standard conditions (298 K, atmospheric pressure). The inorganic compound refers to a compound that does not contain carbon atoms and a compound that contains one carbon atom and does not contain hydrogen atoms.
The term "fluorohydrocarbon" refers to a compound in which at least one hydrogen atom of a hydrocarbon compound has been substituted with a fluorine atom, and includes a compound in which all hydrogen atoms of a hydrocarbon compound have been substituted with fluorine atoms.

According to the method for producing fluorocarbons of the present invention, it is presumed that fluorocarbons are produced as follows.
When a compound represented by formula 1: CH ₃ -R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding a hydrocarbon group)) is supplied to a thermal non-equilibrium region of a plasma device, various active species are generated from the compound of formula 1 in this region. In the thermal non-equilibrium region of the plasma device, decomposition of the compound of formula 1 is appropriately suppressed, and the generated active species contain a sufficient amount of radicals and ions containing a partial structure of the compound of formula 1, such as CH ₃ radicals and CH ₃ ions (hereinafter also referred to as "CH ₃ radicals, etc."). At that time, active species derived from a solid fluorine-containing inorganic compound are allowed to exist in the thermal non-equilibrium region of the plasma device. The active species derived from a solid fluorine-containing inorganic compound contain at least one of fluorine ions and fluorine radicals (hereinafter also referred to as "fluorine source").
Then, the gas in the thermally non-equilibrium region of the plasma device, which contains active species (including _CH3 radicals, etc.) generated from the compound of formula 1 and active species (including a fluorine source) derived from the solid fluorine-containing inorganic compound, is continuously released to the outside of the plasma device, whereby these active species combine to generate fluorohydrocarbons. In this way, by utilizing plasma, fluorohydrocarbons can be easily produced in the gas phase without using a catalyst. In this case, by using a solid fluorine-containing inorganic compound to generate the fluorine source, fluorohydrocarbons can be produced at low cost.

In the method for producing fluorocarbons of the present invention, a device that forms atmospheric pressure low-temperature plasma or vacuum plasma can be used as the plasma device. The discharge region in such a plasma device corresponds to a thermal non-equilibrium plasma region.

Specifically, a solid fluorine-containing inorganic compound is placed in an apparatus for forming atmospheric pressure low-temperature plasma or vacuum plasma, and then an oxygen-containing compound is introduced to generate active species derived from the solid fluorine-containing inorganic compound, and a raw material gas containing the compound of formula 1 and an inert gas can be continuously supplied to this apparatus. This advantageously enables the solid fluorine-containing inorganic compound to be activated in the apparatus that supplies the compound of formula 1.

The generation of a fluorine source from a solid fluorine-containing inorganic compound can be achieved by introducing an oxygen-containing compound into the discharge region in a plasma device to generate oxygen-containing active species (e.g., various ions (oxygen ions, carbonate ions, etc.), various radicals (carbon monoxide radicals, carbon dioxide radicals), etc.), which are then collided with the solid fluorine-containing inorganic compound to knock out the fluorine source. For example, when the starting material is _CaF2 , etc., a stable compound (e.g., carbonate (CaCO3, etc.)) close to its standard formation energy can be expected to be generated in the region by the collision of oxygen-containing active species (e.g., various ions (oxygen ions, carbonate ions, etc.), various radicals (carbon monoxide radicals, carbon dioxide _radicals ), etc.), which is advantageous for the generation of a fluorine source from the viewpoint of Gibbs' free energy.

In addition, in the method for producing fluorohydrocarbons of the present invention, a device that forms atmospheric pressure thermal plasma can be used as the plasma device. The area around the discharge region in such a plasma device reaches a high temperature (approximately 1000 to 3000 K) due to plasma radiation, and this temperature region corresponds to a thermal non-equilibrium region, where chemical species can undergo excitation and dissociation reactions.

When using a device that forms atmospheric pressure thermal plasma, a solid fluorine-containing inorganic compound can be activated in the discharge region of the plasma device to generate a fluorine source. The activated species derived from the solid fluorine-containing inorganic compound can be supplied to a temperature region of 1000 to 3000 K around the discharge region of the same plasma device, which is advantageous in that it is expected to enable simple and efficient production of fluorohydrocarbons.

In the method for producing fluorocarbons of the present invention, the solid fluorine-containing inorganic compound is preferably at least one type of compound represented by formula 2: M-Fx (wherein M is Li, Na, Mg, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Al, B, Cs, Ba, Pb or Sn, and x is the valence of M). These compounds can easily generate a fluorine source. Furthermore, by using these compounds, costs can be easily reduced compared to conventional methods for producing fluorocarbons.

In the method for producing a fluorohydrocarbon of the present invention, the inert gas may be at least one selected from the group consisting of N2 _, Ar and He.

Furthermore, in the method for producing fluorohydrocarbons of the present invention, it is preferable that the content of the compound represented by formula 1 in the raw material gas is 1% by volume or more and 85% by volume or less. If the content is within the above range, the target fluorohydrocarbons can be produced efficiently.

The method for producing fluorohydrocarbons of the present invention can produce monofluoromethane as the target substance.

The present invention provides a method for producing fluorohydrocarbons, including monofluoromethane, simply and inexpensively using a gas-phase flow system without using a catalyst.

FIG. 2 is a schematic diagram of a plasma device used in the examples.

The following describes in detail an embodiment of the present invention.

[Solid fluorine-containing inorganic compounds]
The solid fluorine-containing inorganic compound may be any solid inorganic compound containing one or more fluorine atoms, typically six or less.

Examples of solid fluorine-containing inorganic compounds include compounds represented by formula 2: M-Fx (wherein M is Li, Na, Mg, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Al, B, Cs, Ba, Pb or Sn, and x is the valence of M), such as NaF, KF and Ca ₂ F, with Ca ₂ F being preferred from the standpoints of economy and safety. These may be used alone or in any combination of two or more kinds.

[Compound of Formula 1]
The compound of formula 1 is a compound represented by formula 1: CH ₃ -R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding hydrocarbon groups). The compound of formula 1 may be used alone or in combination of two or more kinds.

Here, organic groups (excluding hydrocarbon groups) refer to functional groups containing at least one carbon atom (excluding those consisting only of carbon atoms and hydrogen atoms), as well as functional groups containing at least one atom selected from oxygen, nitrogen, and sulfur, but no carbon atoms, and examples of such groups include oxygen-containing organic groups, nitrogen-containing organic groups, and sulfur-containing organic groups.

Examples of oxygen-containing organic groups include hydroxy (-OH), carboxy (-COOH), formyl (-CHO), formyloxy (-O-CH(=O)), acyl (-CR ¹ (=O)), acyloxy (-O-CR ¹ (=O)), alkoxy (-OR ¹ ), alkoxycarbonyl (-C(=O)-OR ¹ ), etc., where R ¹ is alkyl, preferably C1 to C4 alkyl, more preferably methyl or ethyl.

Examples of nitrogen-containing organic groups include unsubstituted amino (-NH ₂ ), substituted amino (-NR ² R ³ ), nitro (-NO ₂ ), and cyano (-CN), in which R ² and R ³ are independently hydrogen or alkyl, provided that at least one of them is alkyl, and the alkyl is preferably C1 to C4 alkyl, more preferably methyl or ethyl.

Examples of sulfur-containing organic groups include mercapto (-SH), sulfo (-SO ₃ H), and alkylthio (-SR ⁴ ), where R ⁴ is alkyl, preferably C1 to C4 alkyl, and more preferably methyl.

R is preferably a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, hydroxy (-OH), alkoxy (-OR ¹ ), acyl (-CR ¹ (=O)), or a substituted amino (-NR ² R ³ ) (wherein R ¹ , R ² and R ³ are as defined above), and more preferably a hydrogen atom, a chlorine atom, hydroxy, methoxy, acetyl, or dimethylamino.

Examples of the compound of formula 1 include CH4, _CH3OH , _CH3Cl , _{CH3Br , CH3I, CH3CHO, HCOOCH3, CH3COOCH3, CH3COOC2H5, CH3NH2, (CH3)2NH , ( CH3 ) 3N , CH3CN , CH3NO2 , CH3SH , CH3SCH3 , CH3OCH3 , CH3OC2H5 , CH3COCH3 , and CH3COC2H5 . From the viewpoint} of ease _of handling _{, CH4 , CH3OH} , _{CH3Cl , CH3COCH3} , _{CH3OCH3 , and} ( _CH3 ) ₃ N is preferred, and CH ₃ OH is more preferred.

[Inert gas]
Examples of the inert gas include _N2 , He, Ne, Ar, Xe, Kr, and _CO2 , and ^N2 , Ar, He, and _CO2 are preferred, and _N2 and Ar are more preferred. The inert gas may be used alone or in combination of two or more kinds.

[Raw material gas]
The source gas contains the compound of formula 1 and an inert gas. The compound of formula 1 may be in any of a gas, liquid, and solid state under standard conditions (atmospheric pressure, 298 K), but is in a gas state when the source gas is introduced into the thermally non-equilibrium region.

The content ratio of the compound of formula 1 and the inert gas in the raw material gas is not particularly limited and can be adjusted to any ratio. The content ratio of the compound of formula 1 in the raw material gas is preferably 1 vol.% or more, more preferably 5 vol.% or more, and is preferably 85 vol.% or less, more preferably 80 vol.% or less. The remainder of the raw material gas other than the compound of formula 1 and the inert gas is preferably impurities that are inevitably mixed in from the surrounding environment.

The raw material gas may contain the compound of formula 1 and an inert gas in the thermally non-equilibrium region of the plasma device. The compound of formula 1 and the inert gas may be supplied separately as gases to the thermally non-equilibrium region of the plasma device to be used as the raw material gas, or all of them may be supplied as a premixed gas to be used as the raw material gas, or a portion of them may be supplied as a premixed gas separately from the remaining gas to be used as the raw material gas.

If the compound of formula 1 is a gas under standard conditions, or a liquid with a sufficiently high vapor pressure that can be easily vaporized by heating, etc., the compound of formula 1 can be supplied as a gas to the thermally non-equilibrium region without providing a separate vaporization chamber, etc. The supply flow rate can be controlled using a mass flow controller, etc.

When the compound of formula 1 is a liquid or solid with a low vapor pressure at standard conditions, the compound of formula 1 can be vaporized in a separately provided vaporization chamber and then fed to the gas-phase flow reactor. When it is a solid, it can be heated to make it liquid and then introduced into the vaporization chamber.

For example, the compound of formula 1 can be vaporized by introducing it in a liquid state into a vaporization chamber maintained at a temperature and pressure at which the compound of formula 1 is sufficiently vaporized. The temperature and pressure of the vaporization chamber are preferably maintained at a temperature and pressure at which the compound of formula 1 can be vaporized instantly. By using such a vaporization chamber, the compound of formula 1 can be continuously introduced into the vaporization chamber as a liquid, instantly vaporized in the vaporization chamber, and continuously supplied as a gas to the thermally non-equilibrium region of the plasma device. The supply flow rate can be controlled by controlling the gas vaporized in the vaporization chamber with a mass flow controller or the like, or by controlling the compound of formula 1 when it is continuously introduced into the vaporization chamber in a liquid state with a liquid mass flow controller or the like. The vaporized compound of formula 1 may be diluted with an inert gas when it is introduced into the thermally non-equilibrium region of the plasma device.

[Thermal non-equilibrium region]
In the manufacturing method of the present invention, the raw material gas is introduced into the thermal non-equilibrium region of the plasma device. In the thermal non-equilibrium region of the plasma device, the compound of formula 1 is brought into a thermal non-equilibrium state, and various active species can be generated. In the thermal non-equilibrium region, the decomposition of the compound of formula 1 is appropriately suppressed, which is advantageous in terms of generating _CH3 radicals.

The thermal non-equilibrium region of the plasma device can be a discharge region by atmospheric pressure low temperature plasma or vacuum plasma. An electrical method can be used to generate the atmospheric pressure low temperature plasma or vacuum plasma.
Examples of atmospheric pressure low-temperature plasma include systems in which dielectric barrier discharge, glow discharge, and pulse discharge are performed under low temperature and atmospheric pressure, while examples of vacuum plasma include systems in which glow discharge and high-frequency discharge are performed under low temperature and low pressure.

The thermal non-equilibrium region of the plasma device can also be a reaction field that creates atmospheric pressure thermal plasma, and typically the temperature region of 1000 to 3000 K around the discharge region of the device that creates atmospheric pressure thermal plasma corresponds to the thermal non-equilibrium region.

In the production method of the present invention, the raw material gas is continuously passed through the thermal non-equilibrium region of the plasma device, and the space velocity at that time is not particularly limited and is preferably 0.01 h ^-1 or more, more preferably 0.1 h ^-1 or more, even more preferably 0.3 h ^{-1 or} more, and is preferably 100000 h ^-1 or less, more preferably 50000 h-1 or less, and even more preferably 10000 h-1 or less. If the space velocity is within the above range, it is possible to avoid difficulty in discharge, and fluorohydrocarbons can be efficiently produced without reducing productivity.

[Fluorine source]
In the production method of the present invention, the active species derived from the solid fluorine-containing inorganic compound is present in a thermal non-equilibrium region. The active species derived from the solid fluorine-containing inorganic compound contains a fluorine source.

A solid fluorine-containing inorganic compound can be activated in the thermal non-equilibrium region of a plasma device, and active species can be present in the thermal non-equilibrium region. For example, a method can be used in which a solid fluorine-containing inorganic compound is placed in the thermal non-equilibrium region of a plasma device, and then an oxygen-containing compound is introduced. By introducing an oxygen-containing compound into the thermal non-equilibrium region, oxygen ions and oxygen radicals can be generated in the region, and the fluorine source can be driven out by colliding with the solid fluorine-containing inorganic compound.

For example, the solid fluorine-containing inorganic compound can be applied to a silicon wafer or the like and placed in a plasma device. In this case, the amount of the solid fluorine-containing inorganic compound can be applied so that it is 0.2 mg/ ^cm2 or more, and the thickness of the application is preferably 1 μm or more. Examples of oxygen-containing compounds that are supplied to the thermal non-equilibrium region to generate a fluorine source include _O2 and _SO2 . The oxygen-containing compound may be introduced into the thermal non-equilibrium region of the plasma device together with a raw material gas.
When the inert gas or the compound of formula 1 contains oxygen, they can also serve as the oxygen-containing compound. For example, the inert gas is CO ₂ , and the compound of formula 1 is CH ₃ OH or CH ₃ CHO.
The amount of the oxygen-containing compound is preferably adjusted so that the ratio of the number of oxygen atoms to the number of carbon atoms supplied into the system (number of oxygen atoms/number of carbon atoms) is 0.5 or more and 10 or less.

A source gas containing the compound of formula 1 and an inert gas can be continuously supplied into the plasma device in which the fluorine source is generated as described above.
Alternatively, the generated active species may be supplied to another plasma device for atmospheric pressure low-temperature plasma or vacuum plasma, and a raw material gas containing the compound of formula 1 and an inert gas may be continuously supplied to the other plasma device.

The activation of the solid fluorine-containing inorganic compound can be achieved, for example, by introducing the solid fluorine-containing inorganic compound into the discharge region in the case of an apparatus for forming atmospheric pressure thermal plasma. In this case, it is preferable to continuously supply the solid fluorine-containing inorganic compound, and a quantitative feeder, a disk feeder, a micron feeder, a mono pump, or the like can be used for supplying the solid fluorine-containing inorganic compound. The amount of the solid fluorine-containing inorganic compound is preferably such that the number of fluorine atoms relative to the number of carbon atoms supplied into the system is 0.25 or more and 25 or less.
The generated active species can be supplied to a temperature region of 1000 to 3000 K around the discharge region in the same plasma device. Specifically, the active species generated in the discharge region can be transferred to a temperature region of 1000 to 3000 K around the discharge region.
Alternatively, the generated active species may be supplied to a plasma device for atmospheric pressure low-temperature plasma or vacuum plasma, and a raw material gas containing the compound of formula 1 and an inert gas may be continuously supplied to the plasma device for atmospheric pressure low-temperature plasma or vacuum plasma.

[Fluorocarbons]
Hydrofluorocarbons can be obtained by continuously discharging the gas in the thermal non-equilibrium region of the plasma device to the outside of the plasma device. The gas in the thermal non-equilibrium region contains various active species, including _CH3 radicals generated from the fluorine source and the compound of formula 1. By continuously discharging these to the outside of the region, the fluorine source and the active species combine to generate hydrofluorocarbons. The continuous discharge can be performed at a space velocity corresponding to the continuous flow of the raw material gas.

After the gas is discharged from the plasma device, it may be further cooled by being introduced into a heat exchanger. The type of heat exchanger is not particularly limited, and examples include air-cooling and water-cooling. The discharged material may contain hydrocarbons in addition to the target substance, fluorohydrocarbons, and may therefore be subjected to a separation and purification process. Examples of separation and purification methods include distillation, absorption by a solution, membrane separation, etc.

According to the production method of the present invention, various kinds of fluorohydrocarbons can be produced, and in particular, fluorohydrocarbons having one carbon atom can be produced. Specific examples include _CH3F , _CH2F2 , _CHF3 , and _CF4 . Applications of monofluoromethane ( _CH3F ) include etching gas, and applications _{of difluoromethane} ( _CH2F2 ) and trifluoromethane ( _CHF3 ) include alternative fluorocarbon materials and etching gas. The production method of the present invention is suitable for producing monofluoromethane.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1
A silicon wafer (4 ^inches) ₂ coated with CaF2 at a density of 0.32 mg/cm2 and a thickness of about 1 μm was introduced into a parallel plate type high frequency plasma device 1 (upper electrode 11 (60 MHz), lower electrode 13 (2 MHz), capacity 35 L) shown in Fig. 1. _CH4 as raw material and Ar as inert gas were introduced into the plasma device 1 at flow rates of 25 sccm and 270 sccm, and _O2 was introduced into the plasma device at a flow rate of 5 sccm as a mixed gas G for generating a fluorine source.

In the plasma device 1, with the mixed gas G kept at 10 PaA (absolute pressure), plasma excitation was performed with a power supplied to the upper electrode of 1800 W, and silicon wafer etching was simultaneously performed with a power supplied to the lower electrode of 300 W. The gas P discharged out of the system was cooled only by continuously exhausting it with a vacuum pump at room temperature (298 K), and the gas P was collected in an aluminum bag.

The collected gas P was analyzed by gas chromatography-mass spectrometry (GC-MS) (Agilent Agilent 7890A) and flame ionization gas chromatography (GC-FID) (Agilent Agilent 6890N). The yield of fluorohydrocarbons was calculated from the area values of each component of GC-MS and GC-FID obtained by the analysis. The results are shown in Table 1.
After the reaction was completed, the silicon wafer 2 was removed from the plasma device 1, and the plasma-irradiated surface was observed with a micro infrared spectrophotometer (Nicolet iS10 Fourier transform infrared spectrometer manufactured by Thermo Fisher Scientific ^K.K. ). Peaks derived from _CO3- of _CaCO3 were observed around 870 and 1450 cm ^-1 , confirming that oxygen-containing active species had collided with _CaF2 and the fluorine source had been knocked out.

Example 2
The flow rates of CH ₄ , O ₂ and Ar were changed to 20 sccm, 10 sccm and 270 sccm, respectively, and the other conditions were the same as in Example 1. The results are shown in Table 1.

Example 3
The flow rates of CH ₄ , O ₂ and Ar were changed to 15 sccm, 15 sccm and 270 sccm, respectively, and the other conditions were the same as in Example 1. The results are shown in Table 1.

Example 4
The flow rates of CH ₄ , O ₂ and Ar were changed to 10 sccm, 20 sccm and 270 sccm, respectively, and the other conditions were the same as in Example 1. The results are shown in Table 1.

(Example 5)
The flow rates of CH ₄ , O ₂ and Ar were changed to 15 sccm, 15 sccm and 270 sccm, respectively, and the upper electrode was changed to 500 W, but the same procedure was followed as in Example 1. The results are shown in Table 1.

Example 6
The flow rates of CH ₄ , O ₂ and Ar were changed to 15 sccm, 15 sccm and 270 sccm, respectively, and the upper electrode was changed to 1150 W, but the same procedure was followed as in Example 1. The results are shown in Table 1.

(Example 7)
The flow rates of CH ₃ OH and Ar were changed to 10 sccm and 290 sccm, respectively, and O ₂ was not used, but the other conditions were the same as in Example 1. The results are shown in Table 1.

(Example 8)
The flow rates of CH ₄ , CO ₂ and Ar were changed to 15 sccm, 15 sccm and 270 sccm, respectively, and the other conditions were the same as in Example 1. The results are shown in Table 1.

(Example 9)
The flow rates of CH ₄ , CO ₂ and Ar were changed to 15 sccm, 45 sccm and 240 sccm, respectively, and the other conditions were the same as in Example 1. The results are shown in Table 1.

Example 10
The flow rates of CH ₄ , O ₂ and N ₂ were changed to 15 sccm, 15 sccm and 270 sccm, respectively, and the upper electrode was changed to 500 W, but the same procedure was followed as in Example 1. The results are shown in Table 1.

From Table 1, it can be seen that in the examples, fluorohydrocarbons (monofluoromethane, difluoromethane) can be produced without using a catalyst.

According to the present invention, fluorohydrocarbons can be produced in a gas phase without using a catalyst. The production method of the present invention can avoid a situation in which a yield is reduced due to a decrease in catalyst activity, and can continuously produce fluorohydrocarbons, and has high industrial applicability.

1 Parallel plate type high frequency plasma device 2 Silicon wafer coated with CaF ₂ 11 Upper electrode 12 Matching box 13 Lower electrode 14 Matching box 20 Cooling gas inlet G Mixed gas P Gas

Claims (9)

A raw material gas containing a compound represented by formula 1: CH ₃ -R (wherein R is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, or an organic group (excluding a hydrocarbon group)) and an inert gas is continuously supplied to a thermal non-equilibrium region of a plasma device containing active species derived from a solid fluorine-containing inorganic compound,
and then continuously discharging the gas in the thermally non-equilibrium region out of the plasma device.
Method for producing fluorocarbons. The method for producing fluorohydrocarbons according to claim 1, wherein the plasma device is a device for forming atmospheric pressure low-temperature plasma or vacuum plasma, and the thermally non-equilibrium region is a discharge region within the device for forming atmospheric pressure low-temperature plasma or vacuum plasma. The method for producing fluorohydrocarbons according to claim 2, wherein the solid fluorine-containing inorganic compound is placed in an apparatus for forming the atmospheric pressure low-temperature plasma or vacuum plasma, and then an oxygen-containing compound is introduced to generate active species derived from the solid fluorine-containing inorganic compound. The method for producing fluorohydrocarbons according to claim 1, wherein the plasma device is a device for generating atmospheric pressure thermal plasma, and the thermal non-equilibrium region is a temperature region of 1000 to 3000 K around a discharge region in the device for generating atmospheric pressure thermal plasma. The method for producing fluorohydrocarbons according to claim 4, wherein active species derived from the solid fluorine-containing inorganic compound are generated in a discharge region in the device for forming the atmospheric pressure thermal plasma. The method for producing fluorohydrocarbons according to any one of claims 1 to 5, wherein the solid fluorine-containing inorganic compound is at least one compound represented by formula 2: M-Fx (wherein M is Li, Na, Mg, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Al, B, Cs, Ba, Pb or Sn, and x is the valence of M). The method for producing a fluorohydrocarbon according to any one of claims 1 to 6, wherein the inert gas is at least one selected from the group consisting of N2 _, Ar and He. The method for producing fluorohydrocarbons according to any one of claims 1 to 7, wherein the content of the compound represented by formula 1 in the raw material gas is 1% by volume or more and 85% by volume or less. The method for producing a fluorohydrocarbon according to any one of claims 1 to 8, wherein the fluorohydrocarbon is monofluoromethane.

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