JP2812830B2 - How to remove NF (3) - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a detoxifying method exhaust gas containing NF _3.

[0002]

2. Description of the Related Art With the development of the semiconductor industry, the demand for NF ₃ is rapidly increasing as a dry etching agent and a cleaning agent. NF ₃ , on the other hand, is extremely stable in air at room temperature and is only slightly soluble in water. In addition, since it is a toxic gas having a TLV of 10 ppm, when it is used, it must always be harmed when exhausting residual gas and the like.

NF ₃ is very stable around normal temperature, but decomposes at high temperature into N ₂ and active F atoms. How abating NF ₃ so far developed are based on this principle.

[0004] Specifically, Si, B, W, Mo, V, Se, Te, Ge and 200
Method to react at ~ 800 ° C (Japanese Patent Publication No. 63-48570)
63-48571) A method of reacting with a carbon lump such as charcoal at 300 to 600 ° C (Japanese Patent Publication No. 2-30731). A method of reacting with a transition metal oxide at 250 ° C or higher (Japanese Patent Application Laid-Open No. 3-181316). is there. As a method of removing harm at a lower temperature than these methods, a method of reacting with a metal halide at 40 to 80 ° C (Japanese Patent Publication No. 63-48569) is mixed with hydrogen and contacted with a reducing catalyst in a range of 130 to 180 ° C. Method (JP-A-2-303524).

[0005]

All of the methods (1) to (4) require a high temperature and thus require a large amount of heater and heat retention, have a problem that the apparatus is large, the handling is inconvenient, and the cost is high. Therefore, the development of a method capable of removing harm at a low temperature is desired. Is similar to the present invention, but at a reaction temperature of about 200 ° C. as in the present invention.
F ₃ can not abatement. NF ₃ at a reaction temperature of 250 ° C or higher
Can be harmed, but NO, NO ₂
Occurs, and equipment for removing it is required separately, and there is a problem that the apparatus becomes complicated.

The methods (1) and (2) can remove NF ₃ at a lower temperature than the methods (1) to ( ₃₎ , but in the method (3), the metal halide is very difficult to handle because of its hygroscopicity. The hydrogen used is NF ₃
And an explosion range, and HF is generated as a product.

[0007]

As a result of various studies on these problems, the present inventors have found that a gas containing NF ₃ is brought into contact with and reacted with activated carbon impregnated with a copper compound and / or a nickel compound. Thus, the present inventors have found a method capable of removing NF _3, and have reached the present invention.

That is, the present invention provides an NF_ThreeContaining gas and copper
Activity impregnated with compound or / and nickel compound
Contact with charcoal at a temperature in the range of 100 to 300 ° C.
Release by reacting with substances and / or nickel compounds
NF characterized by leaving _ThreeMethod of abatement, and
Activity with copper compound and / or nickel compound impregnated
The charcoal is characterized in that it is fired at a temperature of 100 ° C. or more.
NF_ThreeIt is an abatement method.

According to the present invention, a gas containing NF ₃ and an activated carbon to which a copper compound and / or a nickel compound are impregnated are used.
The NF ₃ is decomposed and removed by contact with a copper compound and / or a nickel compound in a temperature range of from 00 to 300 ° C. When the temperature is lower than 100 ° C., the reaction rate is slow and the decomposition is insufficient. Absent. Also, 30
NF ₃ but becomes the 0 ℃ more NF ₃ decomposition can be removed
Reacts with activated carbon and generates gases such as CF ₄ and C ₂ F ₆ (which are not toxic but have a problem of global warming), which is not preferable. In particular, it is most preferable to carry out the reaction in the range of preferably 150 to 250 ° C. F of the decomposed NF ₃ is fixed as fluoride of copper and / or nickel,
N is discharged as N _2.

As the copper compound used in the present invention, copper oxyacids such as copper sulfate and copper nitrate, and organic acid coppers such as copper acetate and copper oxalate can be used. As the nickel compound, nickel oxyacids such as nickel sulfate and nickel nitrate, nickel organic acids such as nickel acetate and nickel oxalate can be used.

In the method of attaching a copper compound or / and a nickel compound to activated carbon, a copper compound or / and a nickel compound are first dissolved in a solvent such as water or alcohol to form a solution. Activated carbon is charged therein and sufficiently impregnated with a solution of a copper compound and / or a nickel compound.
Calcination is carried out at 0 ° C. or higher to impregnate the activated carbon with a copper compound and / or a nickel compound. The method of impregnation includes, besides the method of charging activated carbon into the solution, a method of injecting the solution after sufficiently degassing the activated carbon, a method of injecting the solution and a method of spraying the solution on the activated carbon, and the like. May be used. This is fired at a temperature of 100 ° C. or higher. In the fired product, metallic copper and / or metallic nickel was detected from X-ray diffraction, but was an activated reactant or mixture of copper and activated carbon or / and nickel and activated carbon, and was simply copper and activated carbon or / And a mixture of nickel and activated carbon has a different effect. The baking temperature of 600 ° C. or higher is economically disadvantageous without changing the abatement effect, and a baking temperature of 100 ° C. or lower, that is, a reaction temperature or lower is not preferable because the abatement effect cannot be obtained. The firing time varies depending on the amount to be fired, and cannot be unconditionally determined. However, if the firing time is short, the abatement effect is insufficient, and if the firing time is long, it is economically disadvantageous. Preferably, 2 to 5 hours are optimal.

The NF ₃ gas treated in the present invention is N ₂ , A
The present invention is applicable not only to a gas containing NF ₃ diluted with an inert gas such as r or He, but also to a 100% NF ₃ gas.

The contact time may be appropriately selected within a range from 0.1 second to several hours. The pressure is not particularly limited, since the reaction is promoted if the pressure is increased, but it can be removed at a sufficient rate even under atmospheric pressure or reduced pressure.

The reactor is not particularly limited as long as it allows gas and solids to be brought into contact, but a reactor having good solid-gas contact, such as a forced circulation system, a fixed bed circulation system or a fluidized bed system, is particularly preferred. The material is SUS, nickel, Monel,
Copper and the like are preferred.

[0015]

The present invention will be described below in detail with reference to examples. Example 1 Copper (II) acetate monohydrate was used as a copper compound,
g of activated carbon in an aqueous solution of copper acetate in which
g, and the mixture was sufficiently stirred and heated. The water was evaporated and dried, and activated carbon was impregnated with copper acetate. This is filled into a SUS reaction tube having a length of 1/2 inch and a length of 500 mm.
C. for 4 hours. The reaction tube was kept at 200 ° C.
There, 2% NF ₃ was introduced at a rate of 125 cc / min. As a result of analyzing the gas at the reactor outlet by gas chromatography, the NF ₃ concentration was 10 ppm or less. Also, IR
As a result, no products such as CF ₄ , C ₂ F ₆ , NO, and NO ₂ were detected.

Example 2 10% NF using a drug prepared in the same manner as in Example 1
₃ was introduced at a rate of 125 cc / min and treated at 200 ° C. NF ₃ as well as other by-product gases were not detected in the reactor outlet gas.

Example 3 Activated carbon was impregnated with copper acetate under the same conditions as in Example 1;
Using a drug calcined at 0 ° C. for 2 hours, NF ₃ was reacted at the same temperature, concentration and flow rate as in Example 1. NF ₃ as well as other by-product gases were not detected in the reactor outlet gas.

Example 4 Copper nitrate was used as a copper compound, 20 g of activated carbon was added to an aqueous solution of copper nitrate in which 10 g was dissolved in 60 g of water, and the mixture was sufficiently stirred, heated, and evaporated to dryness to form activated carbon. Copper nitrate was impregnated. This is 1/2 inch Φ, length 500m
m, and fired at 500 ° C. for 4 hours. The reaction tube was kept at 200 ° C., and 2% NF ₃
Was introduced at a rate of 125 cc / min. As a result of analyzing the outlet gas of the reactor by gas chromatography, not only NF ₃ but also other by-product gases were not detected.

Example 5 Nickel acetate was used as a nickel compound, and activated carbon 20 was added to a nickel acetate aqueous solution in which 6 g was dissolved in 10 g of water.
g, and the mixture was sufficiently stirred and heated. The water was evaporated and dried, and activated carbon was impregnated with nickel acetate. This is 1/2
Fill into a SUS reaction tube of inch Φ, length 500mm,
It baked at 500 degreeC for 4 hours. The reaction tube was maintained at 200 ° C., and 2% NF ₃ was introduced therein at a rate of 125 cc / min. As a result of analyzing the outlet gas of the reactor by gas chromatography, not only NF ₃ but also other by-product gases were not detected.

Example 6 Using copper acetate as a copper compound and nickel acetate as a nickel compound, 20 g of activated carbon was added to a copper acetate / nickel acetate aqueous solution in which 4 g and 3 g were dissolved in 100 g of water, and the mixture was sufficiently stirred and heated. Then, the water was evaporated and dried, and copper acetate / nickel acetate was impregnated on the activated carbon. This is 1/2
Fill into a SUS reaction tube of inch Φ, length 500mm,
It baked at 500 degreeC for 4 hours. The reaction tube was maintained at 200 ° C., and 2% NF ₃ was introduced therein at a rate of 125 cc / min. As a result of analyzing the outlet gas of the reactor by gas chromatography, not only NF ₃ but also other by-product gases were not detected.

Comparative Example 1 Activated carbon not impregnated with copper acetate was filled in a reaction tube, and
NF at the same temperature, concentration and flow rate as in Example 1_ThreeAnd reacted. Out
As a result of analyzing the mouth gas, NF with the same concentration as the inlet _ThreeIs detected
NF_ThreeHad not been decomposed at all.

Comparative Example 2 After filling copper in a reaction tube and reducing it with hydrogen, it was reacted with NF ₃ at the same temperature, concentration and flow rate as in Example 1. As a result of analyzing the outlet gas, NF ₃ having the same concentration as that of the inlet was detected, and NF ₃ was detected.
₃ had not been disassembled.

Comparative Example 3 Activated carbon mixed with 6 wt% of copper was filled in a reaction tube and reacted with NF ₃ at the same temperature, concentration and flow rate as in Example 1. As a result of analyzing the outlet gas, NF ₃ having the same concentration as that of the inlet was detected, and NF ₃ was not decomposed.

Comparative Example 4 A reaction tube filled with a drug prepared under the same conditions as in Example 1 was heated to 320 ° C., and NF ₃ having the same concentration and flow rate as in Example 1 was used.
Was processed. As a result of analyzing the outlet gas, NF ₃ was not detected, but 200 ppm of CF ₄ was detected.

[0025]

According to the present invention, it is possible to remove NF ₃ -containing exhaust gas at a lower temperature than the conventional method without generating by-product gas.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B01D 53/68 B01D 53/54

Claims (3)

(57) [Claims] 1. A gas containing NF ₃ and activated carbon impregnated with a copper compound and / or a nickel compound are mixed in an amount of 100 to 30%.
A method for removing NF ₃ , comprising contacting at a temperature of 0 ° C. and decomposing and removing it by reaction with a copper compound and / or a nickel compound. 2. The method for removing NF _{3 according} to claim 1, wherein the activated carbon to which the copper compound and / or the nickel compound is attached is calcined at a temperature of 100 ° C. or higher. Wherein said copper compound and / or nickel compounds, oxygen copper, organic copper, oxygen, nickel, abatement method NF ₃ according to claim 1, characterized in that the organic acid nickel.