JP2001190959A - Reactant for decomposition of fluorine compound, decomposition method and its usage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently decompose ad make harmless fluorine compounds giving a noxious influence to the environment, by a simple method. SOLUTION: A reactant containing alumina and an alkaline earth metal compound, to which a metallic oxide is added of necessary, is catalytically decomposed at 200 deg.C or higher, together with the fluorine compounds, thereby the fluorine component of the fluorine compounds is fixed on the reactant. The method for decomposing the fluorine compounds oxidizes carbon monoxide, witch is generated by containing oxygen gas in the fluorine compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to chlorofluorocarbons (hereinafter abbreviated as "CFC"), hydrochlorofluorocarbons (hereinafter abbreviated as "HCFC"), perfluorocarbons (hereinafter abbreviated as "PFC"), Hydrofluorocarbons (hereinafter abbreviated as “HFC”),
Perfluoroethers (hereinafter abbreviated as “PFE”),
Various fluorine compounds such as hydrofluoroethers (hereinafter abbreviated as “HFE”) or sulfur fluoride, and HF, SiF ₄ or HF generated when these compounds are used in, for example, an etching or cleaning step of a semiconductor device manufacturing process. The present invention relates to a reactant and a decomposition method for simultaneously decomposing and rendering a compound such as COF ₂ harmless.

[0002]

2. Description of the Related Art The above-mentioned fluorine compounds are generally stable and are harmless to the human body, so that they are widely used in various fields. In particular, recently, the amount of HFC used for a refrigerant of a car air conditioner and the like and the amount of PFC used for etching and cleaning gas in a semiconductor manufacturing process are increasing. In addition, sulfur hexafluoride is used in a large amount for capacitors, transformers, and the like because of its excellent electrical insulation properties. However, since these fluorine compounds are stable compounds, they have a large global warming potential, and if they are released to the global environment as they are, there is a concern that their effects will continue for a long period of time. In particular, SF ₆ , CF ₄ , C ₂ F _{6 and the} like are extremely stable gases, have a very long atmospheric life, and are emitted after use after being decomposed into harmless substances that do not affect the global environment. There is a need. Further, PFE and HFE, which are considered as substitutes for these compounds, are also compounds that are concerned about global warming, and the gases emitted after being used in the semiconductor device manufacturing process include, for example, HF, SiF ₄ , COF Because it also includes gases such as ₂
It is necessary to safely decompose and discharge each of these compounds together.

On the other hand, CFC, which has been conventionally used in large amounts as a refrigerant, a cleaning agent, and the like, and HCF, an alternative compound thereof, have been used.
Since the destruction of the ozone layer has been raised as a serious environmental problem, C must be decomposed into harmless substances and cannot be emitted as it is. Conventionally, such a fluorine compound decomposition technique includes, for example, a combustion decomposition method for treating with a fuel (WO94 / 05399) and a thermal decomposition method using a reactant such as silica or zeolite (Japanese Patent Application Laid-Open No. 7-116466). Publication), a catalytic decomposition method using alumina or the like (JP-A-10-286434) and the like are known.

However, the methods require generation suppression and large quantities of diluting gas of the NO _X produced by the combustion, resulting in the degradation rate is lowered further, HF contained in the exhaust gas after decomposition There is a problem that secondary processing is required. Is particularly suitable for PFC (CF ₄ , C ₂ F
₆ )) requires a high temperature of 1000 ° C. or more to decompose at a sufficient rate, and furthermore, S contained in the exhaust gas after decomposition.
There is a problem that a secondary treatment of a compound such as iF ₄ is required separately. It is said that the method can be decomposed at a lower temperature than the method. However, in order to decompose PFC by 100%, the concentration of PFC in the supply gas is reduced to a low concentration by diluting it with air or the like. There is a need to. Further, in order for alumina to act as a catalyst, coexistence of a large amount of water vapor for hydrolyzing, for example, fluorides accumulated on the surface of alumina is indispensable. Therefore, a corrosion-resistant material against HF generated by decomposition of water and fluoride on the alumina surface at high temperature, and H
There is a problem that secondary processing of F is required. A method for effectively decomposing a fluorine compound by an industrially advantageous method has not been known so far, and further improvement is desired.

[0005]

In view of the above technical background, the present invention solves the above-mentioned problems by thermally decomposing a fluorine compound at a relatively low temperature without adding water. Decomposition products (F, SO _X
) Is immobilized on the reactant, and particularly the hardly decomposable P
It is an object to provide a method for efficiently decomposing FC.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that in order to decompose fluorine compounds efficiently, a reaction containing alumina and an alkaline earth metal compound is required. It has been found that this problem can be solved by using an agent. Further, the present inventors have found that in the method for decomposing a fluorine compound, the fluorine compound
Chlorine atom produced by catalytic pyrolysis at a temperature of 00 ° C or higher,
Fluorine and / or sulfur atoms can be detoxified by fixing them as chlorides, fluorides and / or sulfates of alkaline earth metals in the reactants. If necessary, metal oxides can be added to the above reactants. It has been found that if oxygen is contained in the fluorine compound, the carbon monoxide produced can be oxidized at the same time to render it harmless, and the present invention has been completed. The present invention relates to a reactant and a method for decomposing a fluorine compound represented by the following (1) to (28).

(1) A reactant for decomposing a fluorine compound, comprising alumina and an alkaline earth metal compound. (2) The reactant for decomposing a fluorine compound according to the above (1), wherein the specific surface area of the alumina is 50 m ² / g or more. (3) The reactant for decomposing a fluorine compound according to the above (1) or (2), wherein the alumina is pseudo-boehmite alumina. (4) The reactant for decomposing a fluorine compound according to the above (1) or (2), wherein the alumina is obtained by firing pseudo-boehmite alumina, and the firing temperature is in a range of 400 to 1000 ° C. (5) The alkaline earth metal compound is magnesium,
The reagent for decomposing a fluorine compound according to any one of the above (1) to (4), which is a carbonate of calcium, strontium or barium.

(6) The decomposition of the fluorine compound according to any one of the above (1) to (5), wherein the particle size of the alumina and the alkaline earth metal compound contained in the reactant is 100 μm or less, respectively. For reactants. (7) The fluorine compound according to any one of the above (1) to (6), wherein the content of alumina and the alkaline earth metal compound contained in the reactant is 1: 9 to 1: 1 by mass ratio. Decomposition reactant. (8) The reaction agent according to any of (1) to (7), wherein the reactant contains at least one oxide of a metal selected from the group consisting of copper, tin, nickel, cobalt, chromium, molybdenum, tungsten, and vanadium. The reagent for decomposing a fluorine compound according to the above. (9) The content of the metal oxide is 1:99 to less than the total mass of the alumina and the alkaline earth metal compound.
The reactant for decomposing fluorine compounds according to the above (8), wherein the ratio is 5:95. (10) The reactant for decomposing a fluorine compound according to any one of the above (1) to (9), wherein the content of the alkali metal contained in the reactant is 0.1% by mass or less.

(11) The reactant is 400 to 700 ° C.
The reagent for decomposing a fluorine compound according to any one of the above (1) to (10), which is a granular product calcined in (1). (12) The reactant for decomposing a fluorine compound according to the above (11), wherein the reactant is a granular product having a particle size in a range of 0.5 to 10 mm. (13) The reactant for decomposing a fluorine compound according to any one of the above (1) to (12), wherein the content of water contained in the reactant is 1% by mass or less. (14) The fluorine compound wherein the fluorine compound is selected from the group consisting of perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin, sulfur fluoride, SiF ₄ and COF ₂ (1) which is at least one of
The reactant for decomposing a fluorine compound according to any one of (13) to (13). (15) The reactant for decomposing a fluorine compound according to the above (14), wherein the fluorine compound contains hydrogen chloride and / or hydrogen fluoride.

(16) A method for decomposing a fluorine compound, comprising bringing the reactant according to any one of the above (1) to (15) into contact with the fluorine compound at a temperature of 200 ° C. or higher. (17) The fluorine according to (16), wherein the concentration of the fluorine compound in the gas to be treated brought into contact with the reactant according to any one of (1) to (15) is in the range of 0.01 to 10 vol%. How to decompose the compound. (18) By contacting the reactant according to any one of the above (1) to (15) with a fluorine compound at a temperature of 500 ° C. or more in the presence of oxygen gas, the generation of carbon monoxide is suppressed. A method for decomposing a fluorine compound, comprising: (19) The method for decomposing a fluorine compound according to (18), wherein the oxygen gas concentration in the gas to be treated is 20 vol% or less. (20) A chlorine atom, a fluorine atom and / or a sulfur atom generated by contacting the reactant according to any one of the above (1) to (15) with a fluorine compound are converted into an alkaline earth metal chloride or an alkaline earth. (16) to (19), which are fixed as metal-like fluorides and / or alkaline earth metal sulfates
The method for decomposing a fluorine compound according to any one of the above.

(21) A fluorine compound selected from the group consisting of perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin and sulfur fluoride as an etching gas or a cleaning gas. An etching step or a cleaning step using at least one of the above, and a decomposition step of decomposing a gas containing a fluorine compound discharged from those steps using the reactant according to any one of the above (1) to (15). A method for manufacturing a semiconductor device, comprising: (22) The gas discharged from the etching step or the cleaning step is perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin, sulfur fluoride, SiF ₄ and COF _2. (21) The method for producing a semiconductor device according to the above (21), wherein the gas is a gas containing at least one fluorine compound selected from the group consisting of: (23) The method of manufacturing a semiconductor device according to (22), wherein the gas containing a fluorine compound contains hydrogen chloride and / or hydrogen fluoride. (24) The above (21) to (21), wherein the decomposition temperature of the fluorine compound in the gas to be treated in the decomposition step is 200 ° C. or higher.
(23) The method for manufacturing a semiconductor device according to any of (23).

(25) The method for manufacturing a semiconductor device according to any one of (21) to (24), wherein the concentration of the fluorine compound in the gas to be treated in the decomposition step is in the range of 0.01 to 10 vol%. (26) The decomposition step is performed at 500 ° C. in the presence of oxygen gas.
A method for manufacturing a semiconductor device, comprising: suppressing the generation of carbon monoxide by performing at the above temperature. (27) The method for manufacturing a semiconductor device according to (26), wherein the concentration of oxygen gas in the gas to be treated in the decomposition step is 20 vol% or less. (28) A chlorine atom, a fluorine atom, and / or a gas generated in the decomposition step of decomposing the gas discharged from the etching step or the cleaning step using the reactant according to any one of the above (1) to (15). (21) wherein the sulfur atom is fixed as an alkaline earth metal chloride, an alkaline earth metal fluoride and / or an alkaline earth metal sulfate.
The method for manufacturing a semiconductor device according to any one of (27) to (27).

That is, the present invention provides a method for decomposing a fluorine compound characterized by containing an alumina and an alkaline earth metal compound, which decomposes a fluorine compound having a high ozone depletion potential or a global warming potential and renders it harmless. Reactant ",
"A method for decomposing a fluorine compound, wherein the fluorine compound is brought into contact with the reactant at a temperature of 200 ° C or higher",
"Oxygen is added to the fluorine compound, and the reactant and 500
By contacting at a temperature of not less than ℃, the method for decomposing a fluorine compound characterized by suppressing the production of carbon monoxide ”and“ etching step or cleaning step,
A method for manufacturing a semiconductor device, comprising a decomposition step of decomposing a gas containing a fluorine compound discharged from these steps using the reactant. ".

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conventional combustion decomposition method described above,
In the thermal decomposition method with the reactant and the alumina catalytic decomposition method, since the decomposition product of the fluorine compound is still a substance that has a harmful effect on the environment, separately after the decomposition step,
It is necessary to add a detoxification treatment step for decomposition products, and there is a problem in downsizing the apparatus. Above all, a gas discharged from a semiconductor device manufacturing process, for example, an exhaust gas of PFC used for etching or cleaning, contains a fluorine compound such as HF, SiF ₄ , and COF _{2 in} addition to PFC. Therefore, to process by the catalytic decomposition method,
In the first stage, a detoxification treatment step for SiF ₄ or the like is required, which makes the apparatus complicated and complicated. In addition, PFC is particularly difficult to decompose and requires a high temperature for decomposition, which causes a problem that the material of the reactor is deteriorated.

On the other hand, according to the present invention, a fluorine compound used for electrical insulation, for a refrigerant, for manufacturing a semiconductor device, and the like can be efficiently decomposed at a low temperature. The present invention relates to a fluorine compound and S produced by using, for example, etching.
Since iF _{4 and the} like are simultaneously decomposed, for example, fluorine generated by the decomposition is fixed as an alkaline earth metal fluoride (for example, CaF ₂ ), and the detoxification reaction proceeds simultaneously, such a problem can be solved at the same time.

Hereinafter, the present invention will be described in detail. The fluorine compound that can be decomposed by the reactant according to the present invention is CFC
For example, CClF ₃ , CCl ₂ F ₂ , CCl ₃ F,
Compounds such as C ₂ Cl ₃ F ₃ , C ₂ Cl ₂ F ₄ and C ₂ ClF ₅ ,
Examples of the CFC include compounds such as CHClF ₂ and C ₂ HCl ₂ F ₃ . As PFC, for example, C
Compounds such as F ₄ , C ₂ F ₆ , C ₃ F ₈ , and C ₄ F ₈ (octafluorocyclobutane);
_{3 F, CH 2 F 2,} CHF 3, compounds such as C ₂ H ₂ F ₄ and the like. As PFE, for example, CF ₃ OCF ₃ , C
Compounds such as F ₃ OCF ₂ CF ₃ and HFE include CHF ₂ O
Compounds such as CHF ₂ , CHF ₂ OCH ₂ CF ₃ , CH ₃ OCF ₂ CF _{3 and the} like can be mentioned. Examples of sulfur fluoride include compounds such as SF ₆ and S ₂ F ₁₀ . The reactant of the present invention can be applied to other compounds, for example, an unsaturated compound CF ₃ OCF = CF ₂
And C ₅ F ₈ (octafluorocyclopentene) compounds such as, or HF contained in the exhaust gas of the etching process of PFC as described above, can be detoxified by decomposition as well compounds such as SiF _4, COF ₂ .

These fluorine compounds may be diluted with an inert gas such as helium, argon, or nitrogen or air, and are liquid at room temperature. However, when they are entrained with other inert gas or air, 0.01 vol% The above-mentioned mixed gas containing the vapor may be used. Further, the fluorine compound may be a single compound or a mixture of two or more compounds.

Next, the reactant for decomposing the fluorine compound of the present invention
Will be described. Decomposition reaction of fluorine compound of the present invention
The agent contains alumina and an alkaline earth metal compound.
There is a feature. Alumina in the reactant is a typical acidic substance
(Solid acid), even if it is used alone, it is a fluorine compound
It is known that can be decomposed. For example, catalyst (Vol.
34, No. 7, p464-469 (1992)) uses alumina with CFC
It can be used as a decomposition catalyst for. So
The content of alumina is generally alumina (Al_TwoO_Three) Using CFC
When decomposed, the fluorine generated by decomposition decomposes aluminum
The surface is fluorinated and AlF_ThreePoisoned as catalyst
Activity is lost in a short time. But generally metal halide
Since compounds are easily hydrolyzed at high temperatures, this property
Using AlF_ThreeIs hydrolyzed in the presence of steam (2
AlF_Three+ 3H_TwoO → Al_TwoO_Three+ 6HF)
That alumina can be used as a catalyst
It is. However, as mentioned above, the reaction in the presence of moisture
Is AlF _ThreeHydrogen fluoride is generated by the decomposition of
The problem of corrosion occurs. Therefore, the present inventors have found that water does not exist.
Fluorine compounds, especially hard-to-decompose PFC,
As a result of studying various decomposers that can be continuously decomposed at low temperatures,
Reactant containing alumina and alkaline earth metal compound
If used, decompose fluorine compounds at a reaction temperature of 200 ° C or higher
Hydrogen fluoride produced is also alkaline earth metal fluoride
Harmless because it can be fixed as
It turns out that it can be converted.

Further, the reactant for decomposing a fluorine compound of the present invention containing alumina and an alkaline earth metal compound is:
As shown below, carbon monoxide may be generated depending on the type of the fluorine compound. (1) CF ₄ + 2CaCO ₃ / Al ₂ O ₃ → 2CaF ₂
+ 3CO ₂ (2) C ₂ F ₆ + 3CaCO ₃ / Al ₂ O ₃ → 3CaF ₂
+ 4CO ₂ + CO In order to oxidize this carbon monoxide, it is sufficient that the oxygen partial pressure is sufficient for the oxidation. However, when the oxygen partial pressure is limited, copper, tin, nickel, cobalt, It was found that addition of at least one oxide of a metal selected from the group consisting of chromium, molybdenum, tungsten, and vanadium enables oxidation to carbon dioxide even at a low oxygen partial pressure. In addition, it is considered that oxides of these metals also function as co-catalysts for breaking carbon-carbon bonds of fluorine compounds.

The alumina used in the present invention is not particularly limited, but the alumina has an active site that determines the decomposition of the fluorine compound and a specific surface area that determines the adsorption of the fluorine compound, that is, pores (diameter and volume of the pores) are sufficiently developed. It is important to choose what has been done. Therefore, it is preferable that the specific surface area of the alumina is 50 m ² / g or more, more preferably it is those which are 100 to 300 m ² / g. Also,
It is important to select a suitable starting material having few impurities. In the present invention, for example, activated alumina or pseudo-boehmite alumina can be used as the alumina raw material, and pseudo-boehmite alumina is preferably used. Pseudo-boehmite alumina can be used as it is by mixing with an alkaline earth metal compound, but when calcining, pseudo-boehmite alumina is heated to 400 to 1000 ° C. in an inert gas such as nitrogen or air, preferably at 400 to 1000 ° C. 500-8
It may be fired at 00 ° C., more preferably at 500 to 600 ° C. for several hours.

The alumina preferably has an alkali metal content of 0.1% by mass or less, more preferably 0.01% by mass or less.
More preferably, the content is 0.001% by mass or less. Further, the particle size of alumina is preferably 100 μm or less, preferably 30 μm or less, more preferably 5 μm or less, and powdery alumina is used.

Next, the alkaline earth metal compound which is one of the components of the reactant will be described. As the alkaline earth metal compound, carbonates, hydroxides or oxides of alkaline earth metals are used, and magnesium, calcium, strontium or barium carbonates are preferably used, and calcium carbonate is particularly preferable. When, for example, calcium carbonate is used as the reactant, fluorine produced by the decomposition of the fluorine compound is converted to C by coexistence with alumina.
By fixing it as aF ₂ , it plays a role of preventing fluorination of alumina and can maintain the decomposition function (activity) of the fluorine compound of alumina.

Like the alumina, the alkaline earth metal compound has a content of alkali metal contained as an impurity of 0.1%.
The content is 1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less. The particle size of the alkaline earth metal compound is 10
The particle size is preferably 0 μm or less, preferably 30 μm or less, more preferably 5 μm or less, and a powdery material is used. Alkaline earth metal compounds having a particle size of 100 μm or less together with alumina are used.
Because they are fine powder, each raw material is easily dispersed among each other, so that the specific surface area of each raw material is increased, the alumina and the alkaline earth metal compound come close to each other as much as possible, and the fluorine compound is decomposed on the alumina surface. This is considered to increase the chances of the reaction between the generated fluorine and the alkaline earth metal compound. Therefore, the specific surface area of the alkaline earth metal compound is preferably 5 m ² / g or more. Specific examples of particularly preferred calcium carbonate raw materials include heavy calcium carbonate (finely ground limestone), light calcium carbonate (also referred to as precipitated calcium carbonate, which is formed by blowing carbon dioxide into lime milk) and And those obtained by neutralizing quicklime or slaked lime with carbonic acid. Preferably, light calcium carbonate containing few impurities such as alkali metals is good, and more preferably, high purity calcium carbonate is good. Although the detailed mechanism by which the reactant of the present invention decomposes the fluorine compound at a low temperature is not clear, almost no effect is recognized in metal oxides such as iron oxide and manganese oxide, and alumina and alkaline earth metal compounds, In particular, it is considered that a specific composite effect is exerted when alumina and an alkaline earth metal carbonate coexist.

Further, oxides of copper, tin, nickel, cobalt, chromium, molybdenum, tungsten and vanadium, which are one of the components of the reactant of the present invention, will be described. As the oxide of the metal, at least one of copper oxide, tin oxide, nickel oxide, cobalt oxide, chromium oxide, molybdenum oxide, tungsten oxide, and vanadium oxide can be added to the reactant. As these metal oxides, copper oxide, tin oxide or vanadium oxide is preferably used, and copper oxide or tin oxide is more preferable. It is thought that these metal oxides also function as cocatalysts for decomposing fluorine compounds,
When, for example, copper oxide or tin oxide is used as a reactant, by coexisting with alumina and an alkaline earth metal compound,
Depending on the type of fluorine compound, carbon monoxide generated by decomposition can be oxidized to carbon dioxide under a low oxygen partial pressure. In addition, these metal oxides have an alkali metal content of 0.1% by mass or less, preferably 0.01% by mass, similarly to the raw materials of the reactant.
Or less, more preferably 0.001% by mass or less. The particle size of the metal oxide is 100 μm
The following is preferred, preferably 30 μm or less, more preferably 5 μm or less, and a powdery one is used.

Next, a method for producing the reactant of the present invention will be described. The method for decomposing a fluorine compound according to the present invention is characterized in that a reactant containing alumina and an alkaline earth metal compound is used. The content ratio of the alumina and the alkaline earth metal compound to be added to the reactant is 1: 1:
It is preferably from 9 to 1: 1 and preferably from 1: 4 to 2: 3.
It is good. Alumina in the reactant efficiently decomposes the fluorine compound by coexisting with the alkaline earth metal compound, but its content may fluctuate as the decomposition reaction proceeds, but at least at the beginning of the decomposition reaction,
It is preferable that the content is 0.1 or more in terms of mass ratio when the mass of the entire reactant is 1, and if this ratio is less than 0.1, decomposition of the fluorine compound may not proceed sufficiently. However, when alumina is contained in such an amount that the mass ratio becomes larger than 0.5, the amount of the alkaline earth metal compound is reduced and the effective utilization of the reactant is reduced. Further, the content ratio of the metal oxide is preferably 1:99 to 5:95 in terms of the ratio of the total mass of the alumina and the alkaline earth metal compound. If this mass ratio is too small, the effect is lost,
If it is too large, the total amount of alumina and the alkaline earth metal compound relatively decreases, and the effect of the metal oxide is saturated, so that the fluorine compound cannot be decomposed efficiently.

The reactant of the fluorine compound of the present invention can be used as it is by mixing the alumina and the alkaline earth metal compound at the above-mentioned mass ratio, adding a metal oxide if necessary, and mixing. However, the water content in each raw material is preferably as small as possible, and the water content in the reactant is preferably 1% by mass or less. The reactant can be granulated and used as a granule.
When granulating the reactant, a binder can be added together with water depending on the particle size of water or the raw material. The binder is not particularly limited as long as it does not affect the blending raw material, but 0.03 to 0.05 can be added in a mass ratio when the total mass of the blending raw material is 1.0. Preferably, fine alumina powder is used. By adding fine alumina powder, the dispersibility of each raw material is further improved, and the hard granulation property of the alkaline earth metal compound is solved.
The particle size of alumina added as the binder is 0.1
μm or less is preferable, and the content of alkali metal contained as an impurity is 0.1% by mass or less, and preferably 0.01% by mass or less. This fine alumina powder is effective even in a small amount, and has the advantage that the content of the active ingredient per unit volume of the reactant is relatively hardly reduced. However, the kind and amount are not limited as long as the binder does not affect the performance of the obtained reactant.

As described above, each raw material in the reactant includes fine alumina powder added as a binder,
In any case, the content of the alkali metal is preferably 0.1% by mass or less. When the content of the alkali metal in the reactant is 0.1
When the content is not less than mass%, the active sites on the alumina surface are reduced, and it is considered that the decomposition rate of PFC such as CF ₄ and C ₂ F ₆ is reduced.

In order to produce the granular reactant used in the present invention, after mixing each raw material, an appropriate amount of water is added to granulate the kneaded product to obtain a granular product. As a kneading machine required for the above, one capable of simultaneously performing mixing and granulation is convenient, but a mixer capable of performing mixing and granulation separately may be used. For example, if a Henschel mixer or a vertical mixer is used, mixing and granulation can be performed at the same time, but mixing of the raw materials is performed using a Henschel mixer or a V-type mixer, and then granulation is performed using a dish-type granulator or a drum pelletizer. You may go in.

Next, the granules are dried in an inert gas such as nitrogen or air at 100 to 200 ° C. to evaporate water. The reason for the granular product is to increase the decomposition activity of the reactant and to increase the hardness to prevent crushing and powdering during filling and handling in the reaction vessel. For this purpose, the granular product is preferably further calcined, that is, the granulated and dried product is in an inert gas such as nitrogen or air in the range of 400 to 700 ° C, preferably 500 to 700 ° C.
It is fired at 700 ° C. The temperature of 400 ° C. or higher is
It is for further evaporating the water added in the granulation step to increase the decomposition activity and for further increasing the hardness. 7
At a temperature higher than 00 ° C., it is not clear whether the alkaline earth metal compound decomposes (eg, CaCO ₃ → CaO + CO ₂ ), but the decomposition rate (activity) of the reactant decreases. That is, it is important that the bound water of alumina is almost completely dehydrated at 700 ° C. or lower where the activity of the reactant does not decrease, and the water content of the reactant after calcination is reduced in an inert gas or air atmosphere. It is preferable that the amount of released water when heated to 550 ° C. is 1% by mass or less. Also,
As the equipment used for firing, a continuous type such as a rotary kiln can be used, but it is also possible to use a fixed type furnace.

As described above, the reactant for decomposing a fluorine compound of the present invention contains alumina and an alkaline earth metal compound as essential components. Further, when carbon monoxide is generated, the oxide of a metal selected from the group consisting of copper, tin, nickel, cobalt, chromium, molybdenum, tungsten, and vanadium to oxidize to carbon dioxide even under low oxygen partial pressure conditions. At least one of The reactant is preferably granular in order to increase the chance of contact with the fluorine compound subjected to decomposition, and if the particle size is too large, the surface area involved in the adsorption and diffusion of the fluorine compound gas becomes relatively small, and Speed slows down. Conversely, if the particle size is too small, the surface area involved in adsorption and diffusion becomes relatively large, and the diffusion speed increases.However, when the amount of gas to be treated increases, the differential pressure also increases, and the reaction vessel becomes compact. Cause trouble. Therefore, the particle size of the reactant is preferably in the range of 0.5 to 10 mm, preferably in the range of 1 to 5 mm.

Next, the method for decomposing a fluorine compound of the present invention will be described. When a fluorine compound is brought into contact with the reactant produced by the above-described method at an appropriate temperature, the fluorine compound is decomposed, and the chlorine atoms and / or fluorine atoms generated by the decomposition are chlorinated alkaline earth metals and / or fluorine. Fixed to the reactant as a compound. In addition, S
When sulfur fluoride such as F ₆ is contained, the sulfur atom generated by the decomposition is fixed to the reactant as a sulfate of an alkaline earth metal, and the formation of sulfur oxide can be prevented.

That is, when the decomposition reagent according to the present invention is used, harmful decomposition products such as HF, SiF ₄ ,
Fluorine compounds can be efficiently decomposed without discharging compounds such as COF ₂ or SO _X. But,
In order not to discharge such products in the cracked gas, further reaction conditions such as reaction temperature, concentration of fluorine compound in the gas to be treated to be subjected to decomposition, presence or absence of oxygen, form of the reactant, gas to be treated It is necessary to adjust the feed rate appropriately, but the most important condition is the reaction (decomposition start)
Temperature.

The reaction temperature varies depending on the type of the fluorine compound contained in the gas to be treated. For example, PFC is classified as a hardly decomposable compound among fluorine compounds. Among them, CF ₄ , C ₂ F _{6 and the} like are the most hardly decomposable. In order to decompose only by thermal decomposition, a high temperature of 1200 to 1400 ° C. is required. Although required, the method of the present invention can decompose at 550 ° C. or higher. Further, according to the method of the present invention, HCFC CHClF ₂ can be decomposed at a temperature of 200 ° C. or higher. As described above, the decomposition temperature varies widely depending on the type of the fluorine compound, and it is important to set the reactor at the optimum temperature depending on the type of the compound.

In addition, since the reaction temperature varies depending on the type and structure of the compound as described above, when many types of PFC and HFC are contained, such as exhaust gas from an etching or cleaning step in a semiconductor device manufacturing process, To detoxify all these fluorine compounds,
The reaction temperature may be 550 ° C. or higher. Here, for example, when a carbonate is used for the alkaline earth metal compound,
Carbon derived from the fluorine compound is oxidized by oxygen released from decomposition of the carbonate, and is mostly released as CO ₂ . In addition, CO may be generated depending on the type of fluorine compound, but by coexisting oxygen in the gas to be treated, CO is also easily oxidized to CO ₂ with the same reactant,
Can be completely harmless.

That is, the decomposition treatment of the fluorine compound according to the present invention can be carried out by ventilating a gas containing the fluorine compound into a reaction vessel filled with the reactant.
At that time, the decomposition temperature may be maintained according to the decomposability of the fluorine compound. Further, even if the reaction atmosphere is a non-oxidizing atmosphere, the object can be sufficiently achieved, but the generated CO
In order to make the concentration below the allowable concentration, an oxidizing atmosphere, for example, 20
If the treatment is performed in an atmosphere containing an oxygen gas of not more than vol% in the gas to be treated, CO can be treated at the same time. Here, the reason why the oxygen gas concentration is 20 vol% or less is that it is preferable to use air as the diluent gas. Even if the oxygen gas concentration is higher than that, the effect is saturated and the decomposition performance is not improved.

The concentration of the fluorine compound in the gas to be treated is not particularly limited, but if it is too low, it is economically disadvantageous. Also, if it is too high, it depends on the type of the fluorine compound, but the reaction temperature rises due to the heat of decomposition generation, and it may be difficult to control the temperature of the reaction vessel,
The content is preferably in the range of 0.01 to 10 vol%. It is preferable to dilute with an inert gas or an oxygen gas-containing gas (including air) so as to be preferably in the range of 0.01 to 5% by volume, and more preferably in the range of 0.01 to 3% by volume. The concentration is not limited as long as the heat can be forcibly removed and controlled.

The kind and concentration of the fluorine compound in the gas to be subjected to the decomposition as described above, the oxygen gas concentration in the gas to be treated, the SV (superficial velocity), the LV (linear velocity) and the state of mixture with other gases In consideration of the above, preferable reaction conditions are set. In this decomposition treatment, a reaction vessel filled with the reactant, a gas inlet to be treated provided to communicate with the inside of the reaction vessel, and a gas after the reaction from the inside of the reaction vessel are provided. The gas to be treated and the fluorine compound gas source are connected to a gas exhaust port, a furnace for accommodating the reaction vessel, and a decomposition apparatus comprising a heat source for raising the atmosphere in the furnace to a predetermined temperature. It can be done by connecting with.

FIG. 1 shows an example of an apparatus for implementing the present invention. While a certain amount of gas is supplied as a carrier gas from the nitrogen gas supply line 2 or the air or oxygen gas supply line 3 in advance, the preheating section 9 for the gas to be treated in the reaction vessel 8 and the reactant 12 And
The temperature is increased to a predetermined temperature by an electric heater 11 by a temperature sensor 7 and a temperature control device 10 provided in the reaction vessel 8 and controlled to a constant temperature.

When the temperature is controlled to a predetermined value, the gas to be treated is supplied to the fluorine compound gas supply line 1 and the nitrogen gas supply line 2.
Alternatively, the mixture is led from the air or oxygen supply line 3 to the mixer and the header 4 through each valve. The mixed gas to be treated is led to the reaction vessel 8 via the gas introduction pipe 6. The to-be-processed gas guided to the reaction vessel 8 and heated by the preheating unit 9 is:
The fluorine compound is decomposed by contact with the reactant which has been raised to a predetermined temperature. The decomposed processing gas (exhaust gas) is cooled to a predetermined temperature by a cooler 14 (water cooling or air cooling is also possible), and exhausted from a discharge pipe 16. In addition, near the inlet and outlet of the reaction vessel 8 for gas sampling,
By providing sampling ports for the gas 5 to be processed and 15 for the processing gas, respectively, component analysis of each gas can be performed.

Thus, the fluorination in the gas to be treated is
The compound can be decomposed almost completely (with a decomposition rate close to 100%)
You. The fluorine component in the decomposed fluorine compound is, for example, C
aF _TwoAs stable as alkaline earth metal fluoride
Is fixed to the reactant, and carbon is mostly CO2_TwoAs
It is exhausted together with a diluent gas such as a raw gas. Therefore, processed
Harmful substances such as fluorine components or carbon monoxide
Is a harmless gas that does not substantially remain.

When the decomposition ability of the charged reactant is exhausted, the decomposition reaction is terminated. The end point of the decomposition reaction can be known from the time when the fluorine compound starts to be detected. When the fluorine compound is detected and the decomposition ability of the reactant is lost, the operation of the device is stopped, a new reactant is charged and the decomposition reaction is started, and the reactant is charged sequentially or in advance with the same device. The fluorine compound can be decomposed by replacing the spare reaction container with the used one.

In order to make this batch system continuous, a plurality of similar reaction vessels are provided side by side, and while one of the reaction vessels is in operation, the reactants in the other reaction vessel are replaced or the reactants are previously prepared. It is also possible to adopt a double-column switching method in which the filled reaction vessel is replaced, and when one reaction vessel stops, the gas flow path is switched to the other reaction vessel. In addition, if a continuous or intermittent supply of the reactant into the reaction vessel and a continuous or intermittent discharge of the used reactant from the reaction vessel are used, the same apparatus can be operated continuously for a long time.

As described above, according to the present invention, a fluorine compound can be efficiently decomposed, and substantially no harmful substances such as a fluorine component or carbon monoxide remain in the exhaust gas. The fluorine compound described here can be used as an etching gas in an etching step in a semiconductor device manufacturing process or a cleaning gas in a cleaning step, and can be used as the above-described perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, and perfluorocarbon. It is at least one fluorine compound selected from the group consisting of fluoroether, hydrofluoroether, fluorinated olefin and sulfur fluoride. The present invention provides an etching step or a cleaning step using the above-mentioned fluorine compound as an etching gas or a cleaning gas, and a reaction containing the above-mentioned alumina and an alkaline earth metal compound containing the fluorine compound discharged from those steps. A method for manufacturing a semiconductor device having a decomposition step of decomposing by using an agent, wherein the gas containing the fluorine compound discharged from the etching step or the cleaning step can be decomposed efficiently and made harmless.

In a process of manufacturing a semiconductor device such as an LSI or a TFT, a thin film or a thick film is formed by using a CVD method, a sputtering method, or a vapor deposition method, and etching is performed to form a circuit pattern. In an apparatus for forming a thin film or a thick film, cleaning is performed to remove unnecessary deposits deposited on an inner wall of the apparatus, a jig, and the like. This is because the generation of unnecessary deposits causes the generation of particles, and it is necessary to remove the deposits as needed in order to produce a high-quality film.

Here, for example, the above-mentioned fluorine compound is used.
Etching methods include plasma etching and microwave etching.
It can be performed under various dry etching conditions such as etching.
Wear. In the gas discharged from this etching process,
Other than the fluorine compound, for example, SiF_FourOr CO
F_TwoSuch as hydrogen chloride or hydrogen fluoride
Unequal gas may be generated.
By using the reactant of the present invention,
Can also be decomposed at the same time, chlorine atom or
Fluorine atom is chloride or fluoride of alkaline earth metal
Immobilized as a substance, the carbon atoms decompose to carbon dioxide,
Can be harmless. In addition, the type of fluorine compound
Depending on the case, CO may be generated.
By coexisting oxygen gas with the gas to be treated,
CO is easily CO _TwoOxidized and completely harmless
Can be.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but the present invention is not limited to these Examples. (Preparation Example of Reactant) Various raw materials of the reactant used in the test are shown in Table 1.

[0047]

[Table 1]

In order to distinguish the same substance in each raw material name of the reactants in Table 1 by grade, alphabetical letters (eg, CaCO ₃ -a) or Arabic numerals are added after the chemical formula of the substance. This distinction also corresponds to Tables 2 to 6, which describe Examples and Comparative Examples. Using the substances shown in Table 1 as raw materials, for example, each of the substances under the test conditions 1 shown in Table 2 and a binder were blended, mixed with a Henschel mixer, added with water, granulated, and dried at 110 ° C. for 3 hours. Perform processing, sieving and particle size 0.85 to 2.8m
m were obtained. Table 2 shows the obtained granules in air atmosphere.
550 ° C or 700 ° C as shown in Test Condition 2
A heat treatment was performed in an (electric furnace) for 3 hours, followed by dehydration and baking to prepare a reactant.

(Reaction Example) The method of the present invention was carried out using an apparatus having the same principle as that shown in FIG. That is, along the axial center of an annular furnace (electric capacity 1.4 KW, length 400 mm) equipped with a heating element (kanthal alloy) that generates heat by energization, an Inconel 60 having an inner diameter of 16 mm and a length of 500 mm is provided.
0 (or SUS310S) was penetrated, and 35 cc of a reactant for decomposing a fluorine compound was filled in the center of the furnace inside the reaction tube. Using a fluorine compound to be decomposed, oxygen gas was added to the fluorine compound as shown in FIG. 1 or nitrogen gas was introduced as a carrier into the above-mentioned reaction tube as shown in FIG. At that time, the flow rate of the gas to be treated: 0.20 l / min The concentration of the fluorine compound in the gas to be treated: 0.5 to 3 vol% The superficial velocity of the gas to be treated: 343 hr ^-1 The linear velocity of the gas to be treated: 1.0 m / min The oxygen gas concentration of the gas to be treated: 20 vol% or less.

Also, in some tests, H is contained in the gas to be treated.
F, SiF ₄ or CO gas was allowed to coexist and the reaction tubes were connected. In both tests, when introducing the gas to be treated, the power supply to the heating element was started, and the temperature measured by the thermocouple inserted into the central part of the reactant (the highest temperature part of the bulk of the reactant) was measured. The amount of electricity supplied to the annular furnace was controlled so as to maintain the temperature. The reaction temperature in each table represents this temperature maintained during the reaction. Gas to be treated,
The composition analysis of the processing gas was performed by sampling from each sampling port shown in FIG. 1 and O ₂ , N ₂ , CO, C
O ₂ and fluorine compounds were analyzed using a gas analyzer, and F ions were analyzed by sampling with a fluorine absorption bottle containing caustic soda solution.

The reactant compositions (combinations of the respective substances) and the binders described in Test Conditions 1 in Tables 2 to 6 correspond to the respective raw material names of the reactants in Table 1. For example, CaCO ₃ -a for high-purity calcium carbonate, Al ₂ O ₃ -a for pseudo-boehmite alumina, and binder I for ultrafine alumina binder. Further, the mass after mixing the alumina and the alkaline earth metal compound is set to 1.0, the mass ratio of the binder I is 0.05, and the mass ratio of the binder II is 0.1. did. The decomposition test was carried out based on the reactants under test condition 1 and the test conditions under test conditions 2 shown in Tables 2 to 6, respectively, and the result was the decomposition rate of the fluorine compound every hour after introducing the gas to be treated. And the concentration of CO and F ions contained in the processing gas (vo
1%). Decomposition rate = (concentration of fluorine compound in gas to be treated-concentration of fluorine compound in gas to be treated) / (concentration of fluorine compound in gas to be treated) x 100 (%)

(Examples 1 to 3) CF ₄ decomposition reaction was carried out for the reactants in which the mixing ratio of alumina and calcium carbonate as the reactants was changed as shown in Table 2. Pseudo-boehmite alumina (hereinafter abbreviated as Al ₂ O ₃ -a) was used as alumina, and high-purity calcium carbonate (hereinafter abbreviated as CaCO ₃ -a) was used as an alkaline earth metal compound. The reaction temperature was kept constant at 650 ° C., and the oxygen concentration was set at 3.5 vol%. The results are shown in Table 2. In all cases, the decomposition ratio was 99% or more until 3 hours after the gas to be treated was aerated. Further, as shown in Table 2, F ions and CO were hardly detected in the processing gas of Example 1.

Examples 4 to 6 The reactants prepared under the same conditions as in Example 2 were subjected to a CF ₄ decomposition reaction at different reaction temperatures. The results are shown in Table 2, where the reaction temperature was 6
At 00 ° C., the decomposition rate was 99% or more, and at 700 ° C., the decomposition rate was 99.9% or more until 5 hours after the gas to be treated was passed.

Example 7 The firing temperature of the reactants was 550 ° C.
From 700 to 700 ° C under the same conditions as in Example 6.
The decomposition reaction of ₄ was performed. The results are shown in Table 2. The decomposition rate of CF ₄ was 99% or more in both cases, but the decomposition rate was gradually decreased as compared with Example 6.

Examples 8-9 Examples 2 and 9 were repeated except that the alumina in the reactant was changed to pseudo-boehmite alumina calcined at 550 ° C. for 3 hours (hereinafter abbreviated as Al ₂ O ₃ -b). The decomposition reaction of CF ₄ was performed under the same conditions as in Example 7. However, in Example 8, the decomposition reaction was also performed when Binder II was added. The results are shown in Table 2. Example 8 showed almost the same decomposition rate as that of Example 2, and no difference in binder was observed. In Example 9, as in Example 7, both the calcination temperature and the reaction temperature were set to 700 ° C., and a high decomposition rate could be maintained.

[0056]

[Table 2]

(Examples 10 to 13) Examples 10 to 13 were conducted except that calcium carbonate in the reactants was changed to light calcium carbonate (hereinafter abbreviated as CaCO ₃ -b) and heavy calcium carbonate (hereinafter abbreviated as CaCO ₃ -c). CF _{4 under the} same conditions as 2 and 6
Was decomposed. The results are shown in Table 3. The decomposition rate of CF ₄ corresponds to the total amount of impurities of each calcium carbonate shown in Table 1, and CaCO ₃ -a (Examples 2, 6)> CaCO ₃
-B (Examples 10 and 11)> CaCO ₃ -c (Example 1)
2, 13).

(Examples 14 to 16) The alumina in the reactants was changed to each of the aluminas (Al ₂ O ₃ -b, Al ₂ O _3- ) shown in Table 1.
c, a decomposition reaction of CF ₄ was performed under the same conditions as in Example 13 except that Al ₂ O ₃ -d) was used. The results are shown in Table 3. The decomposition rate of CF ₄ corresponds to the amount of impurities of various Al ₂ O ₃ shown in Table 1, and Al ₂ O ₃ -a (Example 13) ≧ Al ₂ O ₃ −
b (Example 14)> Al ₂ O ₃ -c (Example 15)> Al
It was found that the concentration decreased in the order of ₂ O ₃ -d (Example 16).

Example 17 A decomposition reaction was carried out under the same conditions as in Example 1 except that the fluorine compound was changed from CF ₄ to C ₂ F ₆ . The results are shown in Table 3. The decomposition rate of C ₂ F ₆ was 80% or more until 3 hours after the gas to be treated was ventilated.

Examples 18 to 20 The decomposition reaction of C ₂ F ₆ was carried out under the same conditions as in Example 2 except that the reaction temperature and the oxygen concentration were changed. The results are shown in Table 3. In Example 18, the reaction temperature was set at 600 ° C. and the oxygen concentration was set at 3.5 vol%.
The decomposition rate of C ₂ F ₆ was about the same as that of Example 17, and the effect of suppressing CO generation was not sufficient. In Examples 19 and 20, the reaction temperature was 650 ° C., and the oxygen gas concentration was 0 vol% and 20 vol%.
The decomposition reaction was carried out by changing the amount to vol%. As a result, in both cases, the decomposition rate of C ₂ F ₆ was 90% or more until 3 hours after the gas to be treated was ventilated. CO was 3% in Example 19.
In contrast to the case where the gas was generated in a near range, in Example 20, no detection was performed until 3 hours after the gas to be treated was ventilated. Therefore, in order to suppress the generation of CO almost completely, the oxygen gas should be present. I understood.

[0061]

[Table 3]

(Examples 21 to 24) Used in Example 20
The mass ratio is Al_TwoO_Three-A / CaCO_Three−a = 0.3
/0.7 as the reactant, each metal oxide (Example 21-
V_TwoO_Five, Example 22-SnO _Two, Example 23-CuO +
SnO_Two, Example 24-Cr_TwoO_Three)
And the oxygen concentration was increased from 20 vol% to 3.5 vol.
C% under the same conditions as in Example 20 except that it was changed to 1%._TwoF₆Minute
A dissolution reaction was performed. Table 4 shows the results. _TwoF₆of
Decomposition rate is almost the same as the results of Examples 18 to 20
However, CO is almost free even when the oxygen gas concentration is 3.5 vol%.
Not detected, but by adding metal oxides to the reactants
CO2 can be almost completely oxidized even under low oxygen partial pressure.
I knew I could do it.

(Examples 25 and 26) Two reaction tubes were connected (reactant 35 × 2 = 70 cc), and the reaction temperature was 550 ° C. and 6
Except for changing the 50 ° C. CF ₄ under the same conditions as in Example 2 and C ₂
A decomposition reaction of the mixed gas of F ₆ was performed. The results are shown in Table 4. At the reaction temperature of 550 ° C. in Example 21, the decomposition rate of C ₂ F ₆ was as low as about 70%, but the decomposition rate was almost maintained together with the decomposition rate of CF ₄ . The reaction temperature of Example 650 was 650.
At ° C, both CF ₄ and C ₂ F ₆ could maintain a high decomposition rate.

(Examples 27 to 28) CO, HF, SiF
The decomposition reaction of CF ₄ was carried out under the same conditions as in Example 2 except that coexisting ₄ was used and the concentration was changed. The results are shown in Table 4. In Example 23 in the presence of CO, no CO was detected in the processing gas. In Example 24 in the presence of HF and SiF ₄ , no F ions were detected in the processing gas.

(Examples 29 to 39) The decomposition reaction was carried out under the same conditions as in Example 2 except for the type, concentration and reaction temperature of the fluorine compound. The results are shown in Table 5. As shown in Table 5, each fluorine compound showed a high decomposition rate although the reaction temperature was different. Here, the structures of the fluorine compounds used in Examples 31 to 39 are shown below. EXAMPLE 31 CF ₂ = CF ₂ Example 32 CHClFCF ₃ Example 33 CClF ₂ CClF ₂ Example 34 CH ₂ FCF ₃ Example 35 CF ₃ OCHFCF ₃ Example 36 CF ₃ OCF = CF ₂ Example 37

Embedded image Example 38

Embedded image Example 39 SF ₆

Example 40 CaCO ₃ in the reactant was changed to S
The decomposition reaction of CF ₄ was performed under the same conditions as in Example 2 except that rCO ₃ was used. The results are shown in Table 5, where SrCO
_In the case of _3, the decomposition rate is somewhat reduced but it can be used as a reactant for decomposing fluorine compounds.

(Comparative Examples 1 and 2) Tests were conducted in the same manner as in the Examples, such as Preparation Examples and Reaction Examples of the reactants. The reaction agent was only alumina, and the decomposition reaction of CF ₄ was performed under the test conditions shown in Table 6.
As a result, the decomposition rate rapidly decreased 2 hours after the gas to be treated was ventilated. (Comparative Examples 3 and 4) CaCO ₃ in the reactant was replaced with MnO ₂ and Fe
_A reactant was prepared under the same conditions as in Example 2 except that the reaction was changed to ₂ O ₃ , and a decomposition reaction of CF ₄ was performed at 700 ° C. Table 6 shows the results
, All had low decomposition rates from the beginning.

[0068]

[Table 4]

[0069]

[Table 5]

[0070]

[Table 6]

[0071] (Example 41) CF ₄ is 20 sccm, CHF ₃
The silicon oxide film was etched using an etching gas of 20 sccm and an argon gas of 400 sccm. A part of the gas discharged from the dry etching step was introduced into a device shown in FIG. 1 in which the same reactant as in Example 23 was filled using a nitrogen carrier gas, and a decomposition experiment was performed. Three hours after the start of the decomposition experiment, the gas at the outlet of the decomposition apparatus was sampled and analyzed by gas chromatography. As a result, the concentrations of CF ₄ and CHF ₃ were all 10 volppm or less, and the CO concentration was 10 volppm or less. In addition, when the concentration of fluorine ions was analyzed by a water extraction ion chromatography method, it was 1 volppm or less.

[0072]

As described above, by using the reactant of the present invention, a fluorine compound can be efficiently decomposed at a relatively low temperature and with a simple formulation, and the decomposed fluorine can be fixed as a harmless substance. That is, the present invention can be carried out with a simple decomposition apparatus, the processing operation is simple, the decomposition efficiency is high, and the production of carbon monoxide can be suppressed by coexisting oxygen. In addition, since the decomposition product is a stable alkaline earth metal fluoride such as CaF2, post-treatment is easy. In addition, in terms of the low cost of the reactants, it has an effect not found in the past,
In particular, it can greatly contribute to the decomposition of the used fluorine compound-containing gas generated in the semiconductor device manufacturing process.

[Brief description of the drawings]

FIG. 1 is a system layout diagram showing an example of an apparatus for implementing the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluorine compound gas supply line 2 Nitrogen gas supply line 3 Air or oxygen gas supply line 4 Gas mixing and header 5 Sampling port 6 Gas introduction pipe 7 Temperature sensor (measurement pipe) 8 Reaction vessel 9 Remaining heater 10 Temperature controller 11 Electric heating Vessel 12 reactant 13 air-permeable floor 14 cooling pipe 15 sampling port 16 gas discharge pipe

Continued on the front page (72) Inventor Yuji Hayasaka 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko Corporation Kawasaki Plant (72) Inventor Shinichi Yano 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko Co., Ltd. 4D048 AA11 AB03 BA01Y BA02X BA03X BA15X BA21X BA23X BA25Y BA26Y BA27Y BA35X BA37Y BA38Y BA41X BA45X BB01 CA01 CC53 DA01 DA08 4G069 AA02 BA01A BA01B BB04BBC BCBC BCA BCBC BC54B BC58A BC58B BC59A BC60A BC67A BC68A CA19 DA06 EA02X EB18X EC02X EC03X EC04X EC05X EC22X FB30 FC07 FC08

Claims (28)

[Claims] 1. A reagent for decomposing fluorine compounds, comprising alumina and an alkaline earth metal compound. 2. The alumina has a specific surface area of 50 m ² / g.
The reagent for decomposing a fluorine compound according to claim 1, which is the above. 3. The reactant for decomposing fluorine compounds according to claim 1, wherein the alumina is pseudo-boehmite alumina. 4. The alumina is obtained by calcining pseudo-boehmite alumina, and the calcining temperature is 400 to 100.
The reactant for decomposing a fluorine compound according to claim 1 or 2, which is in a temperature range of 0 ° C. 5. The reactant for decomposing a fluorine compound according to claim 1, wherein the alkaline earth metal compound is a carbonate of magnesium, calcium, strontium or barium. 6. The reactant for decomposing a fluorine compound according to claim 1, wherein the particle size of the alumina and the alkaline earth metal compound contained in the reactant is 100 μm or less, respectively. 7. The content of alumina and alkaline earth metal compound contained in the reactant is 1: 9 to 1: 1 by mass ratio.
The reagent for decomposing a fluorine compound according to any one of claims 1 to 6. 8. The method according to claim 1, wherein the reactant contains at least one oxide of a metal selected from the group consisting of copper, tin, nickel, cobalt, chromium, molybdenum, tungsten and vanadium. A reagent for decomposing a fluorine compound according to the above. 9. The content of the metal oxide is determined by a ratio of the total mass of the alumina and the alkaline earth metal compound,
The reactant for decomposing a fluorine compound according to claim 8, wherein the ratio is 1:99 to 5:95. 10. The reactant for decomposing a fluorine compound according to claim 1, wherein the content of the alkali metal contained in the reactant is 0.1% by mass or less. 11. The reactant for decomposing fluorine compounds according to claim 1, wherein the reactant is a granular product fired at 400 to 700 ° C. 12. The method according to claim 1, wherein the reactant has a particle size of 0.5 to 10 m.
The reactant for decomposing a fluorine compound according to claim 11, which is a granular product having a range of m. 13. The water content of the reactant is 1
The reactant for decomposing a fluorine compound according to any one of claims 1 to 12, which is not more than mass%. 14. The fluorine compound is selected from the group consisting of perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin, sulfur fluoride, SiF ₄ and COF _2. The reagent for decomposing a fluorine compound according to any one of claims 1 to 13, which is at least one kind of a fluorine compound. 15. The reagent according to claim 14, wherein the fluorine compound contains hydrogen chloride and / or hydrogen fluoride. 16. A method for decomposing a fluorine compound, comprising contacting the reactant according to claim 1 with a fluorine compound at a temperature of 200 ° C. or higher. 17. The fluorine compound according to claim 16, wherein the concentration of the fluorine compound in the gas to be treated brought into contact with the reactant according to any one of claims 1 to 15 is in the range of 0.01 to 10 vol%. Disassembly method. 18. A method for suppressing the production of carbon monoxide by bringing the reactant according to claim 1 into contact with a fluorine compound at a temperature of 500 ° C. or more in the presence of oxygen gas. A method for decomposing a fluorine compound. 19. An oxygen gas concentration in a gas to be processed is 20 v
The method for decomposing a fluorine compound according to claim 18, wherein the amount is not more than ol%. 20. A chlorine atom produced by contacting the reactant according to claim 1 with a fluorine compound,
The method for decomposing a fluorine compound according to any one of claims 16 to 19, wherein the fluorine atom and / or the sulfur atom is fixed as an alkaline earth metal chloride, an alkaline earth metal fluoride and / or an alkaline earth metal sulfate. . 21. A fluorine compound selected from the group consisting of perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin and sulfur fluoride as an etching gas or a cleaning gas. An etching step or a cleaning step using at least one kind, and a decomposition step of decomposing a gas containing a fluorine compound discharged from those steps using the reactant according to any one of claims 1 to 15. Manufacturing method of a semiconductor device. 22. A gas discharged from the etching step or the cleaning step is a perfluorocarbon,
Hydrofluorocarbon, chlorofluorocarbon,
22. The semiconductor according to claim 21, which is a gas containing at least one fluorine compound selected from the group consisting of hydrochlorofluorocarbon, perfluoroether, hydrofluoroether, fluorinated olefin, sulfur fluoride, SiF ₄ and COF _2. Device manufacturing method. 23. The method of manufacturing a semiconductor device according to claim 22, wherein the gas containing a fluorine compound contains hydrogen chloride and / or hydrogen fluoride. 24. The decomposition temperature of the fluorine compound in the gas to be treated in the decomposition step is 200 ° C. or higher.
24. The method for manufacturing a semiconductor device according to any one of 1 to 23. 25. The method of manufacturing a semiconductor device according to claim 21, wherein the concentration of the fluorine compound in the gas to be treated in the decomposition step is in the range of 0.01 to 10 vol%. 26. The decomposing step, in the presence of oxygen gas,
A method for manufacturing a semiconductor device, wherein the method is performed at a temperature of 500 ° C. or higher to suppress generation of carbon monoxide. 27. The method of manufacturing a semiconductor device according to claim 26, wherein the concentration of oxygen gas in the gas to be treated in the decomposition step is 20 vol% or less. 28. A gas discharged from the etching step or the cleaning step is generated in a decomposition step of decomposing using the reactant according to claim 1.
22. A chlorine atom, a fluorine atom and / or a sulfur atom are fixed as an alkaline earth metal chloride, an alkaline earth metal fluoride and / or an alkaline earth metal sulfate.
28. The method of manufacturing a semiconductor device according to any one of the above items.