JP2003024741A - Combustion type semiconductor exhaust gas treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion type semiconductor exhaust gas treatment apparatus preventing the adhesion of a silica powder, which is a combustion decomposed product of a monosilane contained in the exhaust gas of a semiconductor manufactur process, to piping during a feed process. SOLUTION: In the combustion type semiconductor exhaust gas treatment apparatus having a combustion furnace 3 of gas to be treated, a cooling part 4 provided under the combustion furnace, a tank 6 provided under the cooling part to receive cooling water and an absorption column 7 provided to the cooling part on the downstream side thereof, the tank 6 provided under the cooling part is extended to the region under the absorption column 7 and a space part 6A is provided between the cooling part 4 and the lower part of the absorption column 7 so as to introduce the gas discharged from the cooling part 4 into the lower part of the absorption column 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion type semiconductor exhaust gas treatment device, and more particularly to a combustion type semiconductor exhaust gas treatment device capable of efficiently removing monosilane and freon gas discharged from a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In recent years, the problem of global warming has been highlighted, and it is required to suppress the emission of exhaust gas such as carbon monoxide and carbon dioxide produced by consuming a large amount of fossil fuel. . The total amount of CFCs emitted from semiconductor manufacturing processes (PFC: Perfluorocarbon) is small, but the global warming potential is said to be 1,000 to 10,000 times that of carbon dioxide CO ₂ , and semiconductor production will continue to increase. Can not be ignored considering. Kyoto Protocol (1997) of the Conference of the Parties to the Framework Convention on Climate Change
(Year), PFC is listed as one of the greenhouse gases to be reduced. In view of such a situation, it is necessary to develop an exhaust gas treatment device that makes CFCs harmless.

There are various types of exhaust gas treatment apparatus, such as a wet type and a catalytic type, but these have problems such as high running cost, and the development of a combustion type processing apparatus having a relatively compact apparatus and low running cost. Is expected. Exhaust gas from the semiconductor manufacturing process contains harmful components such as monosilane in addition to CFCs. In the combustion furnace, CFCs must be decomposed and these harmful gases must also be decomposed. In addition to hydrogen fluoride generated by decomposition, silica powder generated by decomposition of monosilane gas is present.

FIG. 2 is an explanatory view showing the schematic structure of a conventional typical combustion type semiconductor exhaust gas treating apparatus. The to-be-processed gas 21 is introduced into the combustion furnace 22 through the exhaust gas inlet and decomposed by combustion. A cooling unit 23 that cools the combustion gas is provided below the combustion furnace 22, and the silica powder generated by the decomposition of monosilane and the hydrogen fluoride generated by the decomposition of Freon gas are partially collected and removed. Below the cooling unit 23, a cyclone scraper type dust collector 24 for collecting silica powder is provided. After the silica powder is removed here, the exhaust gas is supplied to the absorption tower 25 and the absorption tower 2
After the hydrogen fluoride is completely removed from the exhaust gas in 5, the processing gas 27 containing no harmful component is discharged to the outside from the upper part of the absorption tower. The acid wastewater 26 that has absorbed hydrogen fluoride is temporarily stored in a tank below the absorption tower and then discharged to the outside.

FIG. 3 is an explanatory view showing the schematic structure of another conventional combustion type semiconductor exhaust gas treating apparatus. The gas to be treated is introduced into the combustion furnace 31 through the exhaust gas inlet 30 and decomposed by combustion. Below the combustion furnace 31, there is a cooling unit 3 for cooling the combustion gas.
2 is provided, and further, a cooling unit 33 is provided at the end of the conduit communicating with the cooling unit 32, so as to partially collect and remove silica powder produced by decomposition of monosilane and hydrogen fluoride produced by decomposition of Freon gas. Done. A scrubber device 36 is further provided at the end of the pipeline communicating with the cooling unit 33,
Here, the collection of silica powder and the wet removal of hydrogen fluoride are performed. The exhaust gas leaving the scrubber device is a mist trap 3.
After the mist is removed through 7, the process gas outlet 39
Exhausted from.

In these conventional combustion type semiconductor exhaust gas treatment apparatuses, silica powder produced by the combustion decomposition of monosilane flows from the combustion furnace to the cooling section and further to the dust collecting section and the absorption tower on the downstream side together with the combustion gas. Be transported. However, in these conventional devices, silica powder adheres to the inside of the pipe in the process of transporting the gas to be treated, which clogs the pipe, which hinders continuous operation of the device, and eventually results in monosilane or fluorocarbon gas. There were various problems that efficient removal could not be achieved.

[0007]

The object of the present invention is to eliminate the drawbacks of the prior art described above, and silica powder, which is a combustion decomposition product of monosilane contained in the exhaust gas of the semiconductor manufacturing process, adheres to the pipe during the transportation process. The present invention is to provide a combustion type semiconductor exhaust gas treatment device which prevents continuous operation and thus does not cause a problem of pipe clogging, thereby enabling continuous operation.

[0008]

In order to achieve the above object, the invention claimed in the present application is as follows. (1) A combustion furnace for combusting and decomposing a gas to be treated, a cooling unit provided below the combustion furnace for cooling the gas to be treated after burning with water, and a cooling unit provided below the cooling unit. A combustion type semiconductor exhaust gas treatment apparatus having a tank for receiving cooling water and a wet absorption tower for adsorbing hydrogen fluoride in the gas, which is provided on the downstream side of the cooling unit, wherein: A tank provided below the cooling unit is extended to below the absorption tower, and the gas discharged from the cooling unit is introduced into the lower part of the absorption tower between the cooling unit and the lower part of the absorption tower. A combustion type semiconductor exhaust gas treatment device, characterized by having a space portion.

(2) The combustion type semiconductor exhaust gas treating apparatus according to (1), wherein the gas to be treated contains monosilane. (3) The combustion type semiconductor exhaust gas treatment device according to (1) or (2), wherein a bag filter type dust collecting device for collecting silica powder is provided on the downstream side of the absorption tower. (4) In the combustion type semiconductor exhaust gas treating apparatus, in order to hold the space, means for controlling the upper limit of the water surface level in the tank to a predetermined value or less is provided, (1) to (3) Combustion type semiconductor exhaust gas treatment equipment.

(5) In the above combustion type semiconductor exhaust gas treating apparatus, another side wall (referred to as inner peripheral wall) made of a high temperature heat resistant porous material is provided inside the side wall (referred to as outer peripheral wall) of the combustion furnace. The gas is introduced into the combustion furnace through the inner peripheral wall of the combustion type semiconductor exhaust gas treatment apparatus according to (1). (6) In the combustion type semiconductor exhaust gas treating apparatus, the space between the outer peripheral wall and the inner peripheral wall of the combustion furnace is divided, and a gas feeding means is provided in each space. ) Combustion type semiconductor exhaust gas treatment device as described above. (7) In the combustion-type semiconductor exhaust gas treatment device, the gas introduced into the combustion furnace through the inner peripheral wall is air or nitrogen, (6).

According to the present invention, in a combustion type semiconductor exhaust gas treating apparatus, a tank for receiving cooling water is installed below a cooling section by a water spray provided below a combustion furnace, and the tank is extended below a wet absorption tower. However, by providing a space part so that the gas discharged from the cooling part is introduced into the lower part of the absorption tower, the piping for conveying the gas to be treated after combustion is structurally omitted, and the adhesion of silica powder is prevented. You can Further, in the device of the present invention, the post-combustion target gas discharged from the cooling section is introduced to the lower part of the absorption tower through the space between the ceiling surface of the tank and the surface of the water accumulated in the tank. .
Since the space has a sufficient volume for transporting gas, and the bottom surface of the space in the gravity direction is the water surface, adhesion of silica powder does not occur. Further, even if the silica powder temporarily adheres to the surface of the tank, the silica powder that adheres falls to the lower water surface by its own weight, so clogging due to the adhesion of silica powder in the space inside the tank is completely prevented. can do.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 is an explanatory view showing a schematic structure of a combustion type semiconductor exhaust gas treatment apparatus of the present invention. In the figure, the present apparatus comprises a combustion furnace 3 for burning and decomposing a gas to be treated, a cooling unit 4 provided below the combustion furnace for water-cooling the gas to be treated after combustion, and the cooling unit. A tank 6 provided below the section 4 and extending below the absorption tower 7 for receiving at least either water from the cooling section 4 or washing water from the absorption tower 7.
And a wet absorption tower 7 for adsorbing hydrogen fluoride in the gas, which is provided on the downstream side of the cooling unit 4 and above the extended tank 6.

The gas discharged from the cooling unit 4 is introduced into the lower portion of the absorption tower 7 inside the tank 6 provided between the cooling unit 4 and the lower portion of the absorption tower 7. A space portion 6A for forming the space is formed. The space 6A is formed to have a sufficient volume for carrying the gas. Further, the tank 6 is provided with a level gauge 11 for monitoring the water surface level in the tank 6 and a drainage pump 12 for discharging water from the bottom of the tank 6.

In FIG. 1, a semiconductor exhaust gas containing monosilane or chlorofluorocarbon as a gas to be treated is introduced from a treatment gas introducing pipe 1 into an upper part of a combustion furnace 3 and ignited by a burner 2 provided in an upper part of the combustion furnace 3. Combustion is decomposed in the combustion furnace 3. The monosilane contained in the gas to be treated is the combustion furnace 3
By being combusted with, the decomposition product silica is generated as silica powder. The high-temperature post-combustion process gas containing silica powder is cooled by a cooling unit 4 provided below the combustion furnace 3.
And is cooled by the spray water which is introduced into the spray nozzle 5 and is sprayed from the spray nozzle 5. The spray water used for cooling the gas is dropped and stored in a tank 6 provided below the cooling unit 4 and extending below the absorption tower 7. Inside the tank 6, in addition to the spray water, washing water falling from an absorption tower 7 described later is received and stored. By storing these water, a space 6A is formed above the inside of the tank 6 by the inner wall surface of the tank 6 and the surface of the stored water, and the gas discharged from the cooling unit 4 passes through the space 6A to the absorption tower. 7 is introduced at the bottom.

The gas introduced into the absorption tower 7 is introduced into the packed bed 10. The packed bed 10 includes the packed bed 10
Spray water is jetted from a spray nozzle 9 provided above the gas, and the gas introduced into the packed bed 10 comes into contact with the spray water, whereby fluorinated gas which is a CFC gas combustion decomposition product in the gas. Hydrogen is absorbed by the spray water and removed from the gas. The spray water that has absorbed hydrogen fluoride falls in the absorption tower 9 as washing water,
It is received and stored in the tank 6 extending downward. The level of water stored in the tank 6 is monitored by the level meter 11, and the amount of water discharged by the drainage pump 12 is adjusted so that the water level does not exceed a certain upper limit.

Since the bottom surface of the space 6A formed by the inner wall surface of the tank 6 and the water surface of the stored water in the direction of gravity is the water surface, the space 6A is discharged from the cooling section 4 to the lower part of the absorption tower 9 through the space 6A. The silica powder, which is a combustion decomposition product of monosilane in the introduced gas to be treated after combustion, does not adhere to the space 6A. Further, since the space 6A has a sufficient volume for transporting the gas, the gas is sufficiently introduced into the lower part of the absorption tower 9. Furthermore, even if the silica powder temporarily adheres to the ceiling surface of the tank 6, the silica powder that adheres falls on the stored water surface below due to its own weight, so that the space 6A is not clogged due to the adhesion of the silica powder. , Can be completely prevented.

A silica powder dust collector 8 such as a bag filter is provided on the downstream side of the absorption tower 7. The bag filter is sucked by a suction fan (IDF) 13 and is not trapped in the gas. Of the silica powder is collected, and the gas is discharged to the outside of the apparatus after the silica powder is removed. The burner 2 in FIG. 1 has a structure in which the gas to be treated is introduced from the outside of the main body of the burner 2 and combustion air and fuel are premixed inside the burner 2, but in the present invention, For example, the gas to be treated may be introduced from the inside of the burner 2, and the combustion air and the fuel may be introduced from the outside of the main body of the burner 2.

In the combustion furnace 3 in FIG. 1, fuel is fed from above the combustion furnace 3, but inside the wall of the combustion furnace 3 (referred to as an outer peripheral wall), another side wall is provided. (Inner peripheral wall) may be provided, and gas may be introduced into the combustion furnace through the inner peripheral wall. In FIG. 4, the vertical partition plate 58 and the horizontal partition plate 59 are shown as being divided into eight parts. Although not shown, a gas inlet line is connected to each divided space. With the combustion furnace having such a shape, the generated silica can be prevented from adhering to the furnace wall, and the generated silica can be dropped into the tank 6, so that the device as a whole does not generate clogging.

[0019]

According to the inventions of claims 1 to 4,
In a combustion type semiconductor exhaust gas treatment device, silica powder contained in the exhaust gas of the semiconductor manufacturing process is prevented from adhering to the pipe during the transportation process, and the problem of pipe clogging does not occur, so continuous operation of the device is possible As a result, stable combustion can be secured for a long time, and a low utility structure in which pipes from the combustion furnace to the cooling unit and the absorption tower are omitted can be obtained. Furthermore, since there is no clogging of the piping etc. by silica powder, the collection efficiency of silica powder is almost 1
It can be set to 00%.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic structure of a combustion type semiconductor exhaust gas treatment apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a schematic structure of a conventional typical combustion type semiconductor exhaust gas treatment apparatus.

FIG. 3 is an explanatory view showing a schematic structure of a conventional typical combustion type semiconductor exhaust gas treatment apparatus.

FIG. 4 is an explanatory view showing the structure of a combustion furnace of the present invention.

[Explanation of symbols]

1 ... Process gas introduction pipe, 2 ... Burner, 3 ... Combustion furnace, 4 ... Cooling part, 5 ... Spray nozzle, 6 ... Tank, 6A ... Space part,
7 ... Absorption tower, 8 ... Dust collector, 9 ... Absorption tower spray nozzle,
10 ... Packed bed, 11 ... Level meter, 12 ... Drainage pump, 1
3 ... Suction fan (IDF).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // H01L 21/205 F23J 15/00 J (72) Inventor Akira Baba 3 36 Takaracho, Kure City, Hiroshima Prefecture Babcock-Hitachi Kure Institute (72) Inventor Fumihiko Hanayama 6-9 Takaracho, Kure-shi, Hiroshima Babcock Hitachi Ltd. Kure Works (72) Inventor Noboru Toyama 6-9 Takara-cho, Kure-shi, Hiroshima Babcock Hitachi Stock Company Kure Office (72) Inventor Kenshi Kumagai 6-9 Takara-cho, Kure City, Hiroshima Prefecture Babcock Hitachi Co., Ltd. F-Term in Kure Factory (reference) 3K070 DA05 DA24 DA27 DA28 DA37 3K078 AA06 BA20 BA29 CA03 CA12 4D002 AA23 AA26 AC10 BA02 BA05 BA13 BA14 CA01 CA07 CA13 CA20 DA35 EA02 FA10 HA03 4K030 AA06 CA04 CA12 EA12 KA26 5F045 AC01 EG08

Claims (7)

[Claims] 1. A combustion furnace for combusting and decomposing a gas to be treated, a cooling unit provided below the combustion furnace for water-cooling the gas to be treated after combustion, and a cooling unit below the cooling unit. In a combustion type semiconductor exhaust gas treatment apparatus having a tank for receiving cooling water, and a wet absorption tower for adsorbing hydrogen fluoride in the gas, which is provided on the downstream side of the cooling unit A tank provided below the cooling unit is extended to below the absorption tower, and the gas discharged from the cooling unit is introduced into the lower part of the absorption tower between the cooling unit and the lower part of the absorption tower. Combustion type semiconductor exhaust gas treatment equipment characterized in that a space portion is provided as described above. 2. The combustion type semiconductor exhaust gas treating apparatus according to claim 1, wherein the gas to be treated contains monosilane. 3. The combustion type semiconductor exhaust gas treatment apparatus according to claim 1, wherein a bag filter type dust collector for collecting silica powder is provided on the downstream side of the absorption tower. 4. The combustion type semiconductor exhaust gas treating apparatus according to claim 1, further comprising means for controlling an upper limit of a water surface level in the tank to a predetermined value or less in order to hold the space portion. Combustion type semiconductor exhaust gas treatment equipment. The combustion type semiconductor exhaust gas treatment device according to claim 1, which is provided. 5. In the combustion type semiconductor exhaust gas treating apparatus, another side wall (referred to as an inner peripheral wall) made of a high temperature heat resistant porous material is provided inside a side wall (referred to as an outer peripheral wall) of the combustion furnace, The combustion type semiconductor exhaust gas processing apparatus according to claim 1, wherein gas is introduced into the combustion furnace through the inner peripheral wall. 6. The combustion type semiconductor exhaust gas treating apparatus is characterized in that a space between an outer peripheral wall and an inner peripheral wall of a combustion furnace is divided, and a gas feeding means is provided in each space. The combustion type semiconductor exhaust gas treatment device according to claim 5. 7. The combustion type exhaust gas treatment apparatus according to claim 6, wherein in the combustion type semiconductor exhaust gas treatment apparatus, the gas introduced into the combustion furnace through the inner peripheral wall is air or nitrogen.