JP3358130B2 - Gas pyrolysis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas pyrolysis apparatus,
In particular, do not install a heater in the reaction tube filled with filler.
That relates to gas pyrolysis apparatus.

[0002]

2. Description of the Related Art Elimination of harmful gases is an important subject in a semiconductor manufacturing process. Among various harmful gas removal methods, there is a method of removing harmful gases by thermally decomposing them. A conventional gas pyrolysis apparatus used in this method will be described below with reference to FIG. In the conventional gas pyrolysis apparatus, a cylindrical reaction tube 12 is connected to an inlet tube 11 at an upper end thereof, and a discharge tube 13 is connected to a lower end thereof.
Is provided with a heater 14 on its outer periphery. The inside of the reaction tube 12 is filled with a filler S1 having a detoxifying effect by a thermal decomposition reaction on each harmful gas.
The filler S1 is used in a granular form in order to increase the contact area with the harmful gas. Using the device having the above configuration,
Explain the harmful gas removal. The harmful gas is sent from the inlet tube 11 to the reaction tube 12. The inside of the reaction tube 12 is previously heated by the heater 14 to a temperature range of a thermal decomposition reaction of the harmful gas and the filler S1. The harmful gas sent into the reaction tube 12 is detoxified by a thermal decomposition reaction with the filler S1, and is discharged from a discharge tube 13 connected to a lower end of the reaction tube 12.

[0003]

However, the above gas pyrolysis apparatus has the following problems. That is, the filler S
1 is that the particle size becomes smaller as the thermal decomposition reaction is repeated,
It becomes powder filler S2. By further repeating the thermal decomposition reaction, the powder filler S2 is eventually consumed. However, the powder filler S2 having a reduced particle diameter falls downward in the reaction tube 12 before it is consumed and disappears. Both ends of the reaction tube 12 are regions where the thermal decomposition reaction is unlikely to occur, and the dropped powder filler S2 does not repeat the thermal decomposition reaction anymore, and thus does not become exhausted. Further, since the filler S1 reduced by the thermal decomposition reaction is replenished from the upper part of the reaction tube 12, the filler S2 remains at the lower end of the reaction tube 12. By repeating the above, the powder filler S2 gradually accumulates at the lower end of the reaction tube 12, closes a portion communicating with the reaction tube 12 and the discharge tube 13, and causes gas clogging.
The above is the same even if the flow of gas is reversed. An object of the present invention is to solve the problems described above.

[0004]

According to the present invention, there is provided an inlet pipe for introducing a harmful gas containing fluorine.
A reaction tube connected to the inlet tube and filled with a filler containing silicon, a discharge tube connected to the reaction tube and discharging a reaction gas of the harmful gas and the filler, and a heater for heating the reaction tube The reaction tube is located below the inlet and outlet tubes, and reacts with harmful gases to reduce the particle size.
The part of the reaction tube where the filler falls and stays,
Than the connection between the reaction tube and the introduction tube and the discharge tube.
It is a gas pyrolysis apparatus characterized by being installed below . The present invention is also a gas pyrolysis method for detoxifying harmful gas containing fluorine using such a gas pyrolysis apparatus.

[0005]

In the gas pyrolysis apparatus having the above configuration, the gas pyrolysis apparatus
When harmful gas is introduced into the reaction tube, the filler in the reaction tube
Reduced particle size by thermal decomposition of harmful gas to become powder filler
In the reaction tube, the powder filler fills the gap between the fillers.
Fall. For this reason, the bent part of the reaction tube will face downward
By arranging the gas pyrolysis unit as described above,
The filler falls to the bent portion. This bend
Between the connection with the inlet pipe and the connection with the discharge pipe
Since the pyrolysis reaction is active, the powder filler is not
In addition, the particle size becomes smaller due to the thermal decomposition reaction,
Wear out. Therefore, powder filler is deposited in the reaction tube.
I will not do it.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of a gas pyrolysis apparatus showing a first embodiment. This apparatus comprises a reaction tube 2 and one end of the reaction tube 2
And a reaction tube 2 connected to the other end of the reaction tube 2.
And a discharge pipe 3.
It has a covered structure. Between the inlet pipe 1 and the outlet pipe 3
The reaction tube 2 is provided with a bent portion 2a. this
The reaction tube 2 has, for example , a U-shape having a bent portion 2a at an intermediate portion, and is installed such that a connection portion between the introduction tube 2 and the discharge tube 3 is directed upward and the bent portion 2a is directed downward. The inside of the reaction tube 2 is filled with a filler S1 having a detoxifying effect on each harmful gas by a thermal decomposition reaction. The filler S1 is packed as particles in consideration of increasing the contact area with the harmful gas to promote the thermal decomposition reaction and not to obstruct the gas flow. The heater 4 is for heating the inside of the reaction tube 2 to a temperature range of a thermal decomposition reaction. For this reason, the heater 4 is provided all around the reaction tube 2.
Is provided, the temperature distribution inside the reaction tube 2 is kept uniform, and the area of the thermal decomposition reaction inside the reaction tube 2 is made wider.

Hereinafter, a case where SiO ₂ is filled in the reaction tube 2 as the filler S1 will be described taking as an example the removal of harmful gas NF ₃ . SiO ₂ has a detoxification effect of a thermal decomposition reaction with respect to NF _3. The particle size of the filler S 1 made of SiO ₂ filled in the reaction tube 2 is preferably about 2 mm in consideration of the above. First, the reaction tube 2 filled with the filler S1 made of SiO _{2 is} previously placed on NF ₃ and SiO 2.
₂ is heated to 600 ° C. where a thermal decomposition reaction occurs. Next, a harmful gas (hereinafter, referred to as NF ₃ ) is sent from the introduction tube 1 to the reaction tube 2. Then, inside the reaction tube 2, NF ₃ is detoxified by a thermal decomposition reaction with the filler S1 made of SiO _2, and becomes SiF ₄ gas. The SiF ₄ gas is discharged from the discharge pipe 3.

On the other hand, as the filler S1 made of SiO ₂ repeats the thermal decomposition reaction, the particle size becomes smaller and becomes the powder filler S2 as it repeats the thermal decomposition reaction, and falls in the reaction tube 2 toward the bent portion 2a. Here, both ends of the reaction tube 12, that is, the introduction tube 1
The connecting portion with the discharge pipe 3 is a region where the thermal decomposition reaction hardly occurs, whereas the bent portion 2a provided therebetween is a position where the thermal decomposition reaction actively occurs. For this reason, the powder filler S2 that has dropped toward the bent portion 2a repeats the thermal decomposition reaction with the harmful gas and eventually is not consumed. Further, the smaller the particle size, the larger the surface area, so that the thermal decomposition reaction is promoted. The reduction amount of the SiO ₂ filler S1 consumed by the thermal decomposition reaction is determined by a U-shaped reaction.
Refill from the top of tube 2 .

Next, a second embodiment will be described with reference to FIG. In the second embodiment, as shown in FIG. 2, the bent portion 2a of the reaction tube 2 of the first embodiment is rounded at an angle. The corner of the bent portion 2a is deviated from the gas flow, and it is considered that the powder filler S2 is likely to be deposited. This is prevented by making the corner round.

A third embodiment will be described with reference to FIG. In the third embodiment, as shown in FIG. 3, the shape of the reaction tube 2 of the first embodiment is J-shaped. The introduction tube 1 and the discharge tube 3 connected to both ends of the reaction tube 2 may be opposite to each other.

[0011]

As described above, according to the gas pyrolysis apparatus of the present invention, the silicon content falling in the reaction tube is reduced.
Powder filler, since the reaction tube disappears consumed by thermal decomposition of a harmful gas containing successively fluorine without depositing it, gas clogging inside the reaction tube can be prevented, noxious gas containing fluorine Semiconductor manufacturing process using
Process safety is improved. In addition, since the filler having a small particle diameter can be collected by the reaction region of the thermal decomposition reaction, the thermal decomposition reaction of the harmful gas by the filler can be promoted. Further, the filler can be easily refilled from above the reaction tube.

[Brief description of the drawings]

FIG. 1 is a sectional view of a gas pyrolysis apparatus of a first embodiment.

FIG. 2 is a sectional view of a gas pyrolysis apparatus of a second embodiment.

FIG. 3 is a sectional view of a gas pyrolysis apparatus of a third embodiment.

FIG. 4 is a sectional view of a conventional gas pyrolysis apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 introduction pipe 2 reaction pipe 2 a bent portion 3 discharge pipe 4 heater S1 filler

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 8/00-8/06 B01D 53/54 B01D 53/68

Claims (6)

(57) [Claims] Claims: 1. A toxic gas containing fluorine is subjected to a thermal decomposition reaction.
In the gas pyrolysis method that removes In the reaction tube located below the inlet tube and discharge tube,
Silicon that reacts with harmful gases to generate reactive gases
Filled with a filler containing By heating the reaction tube, before the introduction tube
Reacting the harmful gas introduced into the reaction tube with the filler
And react with the harmful gas to reduce the particle size.
The filled filler is dropped to the lower part of the reaction tube,
The filler having a reduced diameter is further reacted with the harmful gas.
Respond The reaction gas is discharged from the discharge pipe.
Gas pyrolysis method. 2. A harmful gas containing fluorine is subjected to a thermal decomposition reaction.
In the gas pyrolysis method that removes In the reaction tube located below the inlet tube and discharge tube,
Silicon that reacts with harmful gases to generate reactive gases
Filled with a filler containing By heating the reaction tube, before the introduction tube
Reacting the harmful gas introduced into the reaction tube with the filler
And reacts with the harmful gas to reduce the particle size.
The filler dropped to the bottom of the reaction tube due to
Is further reacted with the harmful gas, The reaction gas is discharged from the discharge pipe.
Gas pyrolysis method. 3. The gas pyrolysis method according to claim 1 , wherein the filler has a particle size of about 2 mm. 4. The gas pyrolysis method according to claim 1 , wherein the reaction tube is heated to 600 ° C. 5. The method according to claim 1, wherein:
Gas pyrolysis method, It falls to the lower part of the reaction tube and further reacts with the harmful gas.
The corresponding filler is regenerated by repeating the thermal decomposition reaction.
A gas pyrolysis method characterized in that it is not consumed by consumption. 6. The gas pyrolysis method according to claim 5, wherein
hand, The reduced amount of the filler due to the thermal decomposition reaction is
A gas pyrolysis method characterized by replenishing from the top.