JP2006116367A - Exhaust gas treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment system capable of sufficiently treating an exhaust gas and enhanced in the rate of operation. <P>SOLUTION: The exhaust gas treatment system S is constituted so as to treat the exhaust gas such as the cleaning gas, the process gas or the like discharged from a semiconductor main process and equipped with a primary treatment unit 1 for removing a powder in the process gas and a secondary treatment unit 2 for heating and decomposing the exhaust gas from the primary treatment unit 1. The secondary treatment unit 2 includes a heating decomposition furnace 11 having a first treatment part 21 for heating and hydrolyzing the cleaning gas by electromagnetic induction heating and a second treatment part 23 for heating and decomposing the process gas by the remaining heat of electromagnetic induction heating. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas treatment system for detoxifying exhaust gas discharged from a semiconductor manufacturing process.

Conventionally, a process gas used in a film forming process of a semiconductor manufacturing process, an etching gas used in a dry etching process, and a cleaning gas for cleaning a plasma CVD apparatus or the like is used. Fluorocarbon; C ₂ F ₆ , C ₃ F ₈ ) gas, NF ₃ gas, SF _{6 and the} like have a global warming potential several thousand to several tens of thousands times higher than CO ₂ and are naturally decomposed. Since it takes thousands of years to tens of thousands of years, there is an international agreement on reducing its use.

  However, since products using semiconductors are increasing, the amount of PFC gas used is increasing at present, and therefore, measures are being taken by detoxifying PFC gas after use.

  A so-called combustion method is known as one method for detoxifying PFC gas and the like. In this combustion method, PFC gas or the like is decomposed by heating using a combustion furnace or the like to decompose into carbon dioxide gas, water, or the like.

  Patent Document 1 proposes an example of an exhaust gas treatment apparatus using electromagnetic induction heating which is a kind of this combustion method.

However, the exhaust gas treatment apparatus according to the proposal of Patent Document 1 has a problem that not only exhaust gas treatment cannot be sufficiently performed but also the operation rate is low.
JP 2002-58961 A

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide an exhaust gas treatment system that can sufficiently perform exhaust gas treatment and has a high operating rate.

  An exhaust gas treatment system of the present invention is an exhaust gas treatment system for treating exhaust gases such as cleaning gas and process gas discharged from a semiconductor manufacturing process, and includes a primary treatment unit for removing powder in the process gas, and an exhaust gas. A secondary processing unit that heats and decomposes, and the secondary processing unit includes a first processing unit that heats and hydrolyzes the cleaning gas, and a second processing unit that heats and decomposes the process gas. It comprises a cracking furnace.

In the exhaust gas treatment system of the present invention, the secondary treatment unit has a first treatment part and a second treatment part concentrically, and is between the first treatment part and the second treatment part. A heating unit composed of an electromagnetic induction heating coil may be provided.
Alternatively, the secondary processing unit has a first processing unit and a second processing unit in tandem, and the first processing unit is an upper pyrolysis furnace including a heating unit including an electric resistance heating coil, The second processing unit may be a lower pyrolysis furnace including a heating unit including an electric resistance heating coil. In that case, it is preferable that the upper and lower pyrolysis furnaces can be freely joined and detached.

  In the exhaust gas treatment system of the present invention, it is preferable that the first treatment unit includes a water addition device for adding moisture.

  Furthermore, in the exhaust gas treatment system of the present invention, it is preferable that a baffle is disposed in the first treatment unit.

  Furthermore, in the exhaust gas treatment system of the present invention, it is preferable that the thermal cracking furnace has a decomposition product accumulation preventing device at the bottom.

  Furthermore, the exhaust gas treatment system of the present invention preferably includes a primary gas cleaning device that cleans the decomposition gas from the secondary processing unit.

  Furthermore, the exhaust gas treatment system of the present invention preferably includes a secondary gas cleaning device for cleaning the decomposed gas after cleaning by the primary gas cleaning device.

  Furthermore, in the exhaust gas treatment system of the present invention, it is preferable that the secondary gas cleaning device includes a gas exhaust part having a cyclone separator.

  According to the present invention, an excellent effect that exhaust gas treatment can be sufficiently performed and the operation rate is high is obtained.

  Hereinafter, although the present invention is explained based on an embodiment, referring to an accompanying drawing, the present invention is not limited only to this embodiment.

Embodiment 1
FIG. 1 shows a schematic configuration of an exhaust gas treatment system according to Embodiment 1 of the present invention, and FIG. 2 shows a schematic block diagram of the system.

The exhaust gas treatment system S heats and decomposes a process gas (eg, SiH ₄ gas) used in a plasma CVD apparatus (not shown) and a PFC gas (eg, C ₃ F ₈ gas) used as a cleaning gas by a so-called combustion method. It is supposed to be.

  Specifically, the exhaust gas treatment system S mainly includes a primary treatment unit 1, a secondary treatment unit 2, a primary gas cleaning device 3, a secondary gas cleaning device 4, and a cleaning water storage tank 5. The bottom of the secondary treatment unit 2 is connected to the front upper surface of the cleaning water reservoir 5, and the bottom of the secondary gas cleaning device 4 is connected to the rear upper surface of the cleaning water reservoir 5. A primary gas cleaning device 3 is disposed at the front end of the cleaning water reservoir 5.

The primary processing unit 1 performs primary processing on the process gas heated and decomposed in the secondary processing unit 2 in such a manner as to remove generated by-product powder such as SiO _2. The As the primary processing unit 1, for example, a powder removal device proposed in Japanese Patent Application Laid-Open No. 11-57365, a powder removal device proposed in Japanese Patent Application No. 2004-126993, and the like can be used. .

  The secondary processing unit 2 heats and decomposes (or heats and hydrolyzes) the cleaning gas and the process gas from the primary processing unit 1, and includes a thermal decomposition furnace 11, a water addition device 12, and an air supply device. 13, a cooling device 14, and a reaction product accumulation preventing device 15.

  The pyrolysis furnace 11 is configured as an electromagnetic induction heating furnace, and heats and hydrolyzes the cleaning gas supplied from the top from the primary processing unit 1 through the cleaning gas supply pipe P1 at a high temperature of 1100 ° C. to 1200 ° C. The cleaning gas processing unit (processing unit 1) 21, the electromagnetic induction coil (heating unit) 22 disposed so as to surround the cleaning gas processing unit 21, and the electromagnetic induction coil 22 are disposed so as to surround the inside. A process gas processing unit (processing unit 2) that heats and decomposes the process gas supplied from the outer periphery through the process gas supply pipe P2 from the next processing unit 1 at an intermediate temperature of 600 ° C. to 800 ° C. by the residual heat of the electromagnetic induction coil 22 ) 23.

  The cleaning gas processing unit 21 is defined by a cylindrical body 21a made of alumina in order to prevent corrosion caused by corrosive decomposition products such as fluorine gas.

  As shown in FIG. 3, a baffle group 24 consisting of baffles 24a arranged in a staggered arrangement is disposed in the cleaning gas processing unit 21, and a sufficient residence time of the processing gas is secured. The baffle 24a is also made of alumina in order to prevent corrosion caused by corrosive decomposition products such as fluorine gas.

  The water addition apparatus 12 has a water addition pipe 12a joined in the vicinity of the joint between the cleaning gas supply pipe P1 and the thermal decomposition furnace 11, and the cleaning gas treatment section 21 is connected from the primary processing unit 1 by this water addition pipe 12a. Moisture is given to the cleaning gas which is sent to the heating and decomposed. Therefore, the cleaning gas is added with water before being heated and decomposed in the cleaning gas processing unit 21, and is heated and decomposed, that is, heated and hydrolyzed together with the added water. Here, the water addition device 12 sprays water into the pipe P1 by dry air, for example, and adds it to the cleaning gas.

  The reason for adding moisture to the cleaning gas is as follows.

Cleaning gas, for example, PFC gas (for example, C ₃ F ₆ ) is heated and decomposed in the cleaning gas processing unit 21, and PFC gas (for example, C ₃ F ₈ ) is decomposed into carbon (C) and fluorine (F). Is done. However, in this state, carbon (C) and fluorine (F) are combined again, and a large amount of C ₂ F ₆ and CF ₄ are generated. C ₂ F ₆ and CF ₄ are substances having an extremely high global warming potential, and even if PFC gas (eg, C ₃ F ₈ ) can be decomposed at a high ratio, the generation of C ₂ F ₆ and CF ₄ is allowed. This does not meet the original purpose of removing PFC gas.

Therefore, when heating and decomposing the PFC gas, water is added in advance, that is, the PFC gas is heated and hydrolyzed, and this configuration is intended to suppress generation of CF _{4 and the} like. In other words, hydrogen (H) and oxygen (O) are supplied in large quantities by heating and hydrolyzing the PFC gas together with water (H ₂ O) to generate hydrogen fluoride (HF) and carbon dioxide (CO ₂ ). As a result, the amount of CF _{4 and the} like produced decreases.

As described above, by configuring the PFC gas to be heated and hydrolyzed, the detoxification rate of the PFC gas (for example, C ₃ F ₆ ) can be increased to about 95%, and C ₂ F ₆ , CF The occurrence of ₄ can be dramatically reduced.

  In particular, since the fluorine gas generated by decomposition is a highly corrosive substance, it is possible to prevent the cylindrical body 21a of the cleaning gas processing unit 21 from being corroded and damaged by the fluorine gas by suppressing the generation thereof. There are also effects such as.

  The air supply device 13 (see FIG. 3) supplies dry air to the cleaning gas processing unit 21 and the process gas processing unit 23 and supplies spraying air to the water addition device 12. That is, after dry air is supplied to the vicinity of the thermal decomposition furnace 11 by the air mother pipe 13a, it is branched into a cleaning gas processing part air supply pipe 13b, a process gas processing part air supply pipe 13c, and a spraying air supply pipe 13d. Then, dry air is supplied to the cleaning gas processing unit 21, the process gas processing unit 23, and the water addition device 12, respectively.

  The tip of the air supply pipe 13b for the cleaning gas processing section is connected to the cleaning gas supply pipe P1 in the vicinity of the thermal decomposition furnace 11. The process gas processing unit air supply pipe 13 c is branched into a required number at the tip, and the tip of each branch pipe is connected to the outer periphery of the pyrolysis furnace 11. The tip of the spray air supply pipe 13 d is connected to the sprayer 12 b of the water addition device 12.

  The cooling device 14 cools the lower flange portion (not shown) of the thermal decomposition furnace 11 by a water cooling method, for example, a water cooling jacket method.

  The decomposition product accumulation preventing device 15 has a required number of injection nozzles 15a (see FIG. 3) disposed on the outer periphery of the bottom of the thermal decomposition furnace 11, and injects water from these injection nozzles 15a to generate a cleaning gas. A water film is stretched on the gas flow path from the processing unit 21, and powder or molten dust (smelt) generated by heating / decomposition or heating / hydrolysis is dropped to the front end side of the washing water storage tank 5 together with the spray water. It is supposed to be.

  The primary gas cleaning device 3 has a required number of cleaning water injection nozzles 3 a disposed at the front end of the cleaning water storage tank 5, and the cleaning water is injected from the injection nozzles 3 a from the thermal decomposition furnace 11. The process gas is cooled while removing the powder and the refined molten dust contained in the dropped and discharged process gas. The removed powder and refined molten dust are stored in the washing water reservoir 5.

  The secondary gas cleaning device 4 includes a cleaning unit 31, a gas exhaust unit 32, and a drain discharge unit 33.

  The cleaning unit 31 includes a cleaning tower 34 and a mist shower mechanism 35 disposed inside the cleaning tower 34. The washing tower 34 has a substantially cylindrical body, and the bottom surface thereof is connected to the upper surface of the washing water reservoir 5 so that the inside communicates with the washing water reservoir 5.

  The mist shower mechanism 35 includes a shower nozzle 35a, a watering tray 35b disposed at a predetermined position below the shower nozzle 35a, and a water supply pipe 35c for supplying water to the shower nozzle 35a. The shower nozzle 35a and the watering tray The combination with 35b is arranged in a plurality of stages in the vertical direction of the washing tower 34.

  Since the cleaning unit 31 is configured as described above, the water spray from the mist shower and the water spray tray 35b while the powder or the like rises in the decomposition gas that has not been removed by the primary gas cleaning device 3 up the cleaning tower 34. Thus, the cracked gas is cooled at the same time as it is reliably removed. Moreover, the wash water after washing falls and is stored in the rear part of the wash water reservoir 5.

  The gas exhaust part 32 includes a cyclone separator 36, a drain pipe 37 that discharges the powder-containing drain separated from the cracked gas by the cyclone separator 36 to the drain discharge part 33, and a gas exhaust pipe 38. The

  The cyclone separator 36 is disposed integrally with the top of the cleaning tower 34, and is provided with a suction port for sucking cracked gas rising up the cleaning tower 34 at an appropriate position, and a drain pipe 37 is provided at the bottom center. ing. The lower end of the drain pipe 37 is joined to the drain discharge part 33. The lower end of the drain discharge part 33 is extended and lowered to the inside of the washing water reservoir 5.

  The flush water storage tank 5 is partitioned by a partition plate 42 having an opening at the bottom at the rear end portion to form an overflow type drainage portion 41. Further, as described above, the primary gas cleaning device 3 is provided at the front end, the secondary processing unit 2 is connected to the front upper surface, and the secondary gas cleaning device 4 is configured on the rear upper surface. 34 is connected.

  Further, the cleaning water reservoir 5 includes a cleaning water circulation mechanism 43, and a part of the stored cleaning water is circulated. A part of the circulation pipe constituting the washing water circulation mechanism 43 is branched, and this branch pipe is connected to the reaction product accumulation prevention mechanism 15 to supply the prevention mechanism 15 with jet water. In the figure, reference numeral 44 denotes a circulation pump.

Embodiment 2
FIG. 4 shows a schematic diagram of the secondary processing unit according to the second embodiment of the present invention. The second embodiment is a modification of the first embodiment, in which the thermal cracking furnace is replaced with the thermal cracking furnace 11 having the cleaning gas processing unit 21 and the process gas processing unit 23 having a coaxial double structure as shown in FIG. As shown, a tandem-type pyrolysis furnace 60 having a cleaning gas processing unit 21 and a process gas processing unit 23 at the top and bottom is provided. That is, the pyrolysis furnace 11 of the first embodiment performs the processing of the cleaning gas and the process gas in parallel, while the pyrolysis furnace 60 of the second embodiment alternately performs the processing of the cleaning gas and the process gas. The remaining configuration of the second embodiment is the same as that of the first embodiment.

  The pyrolysis furnace 60 includes an upper pyrolysis furnace 61 and a lower pyrolysis furnace 62, which are electric resistance heating furnaces arranged in tandem, and a process gas discharge unit 63.

  The upper pyrolysis furnace 61 includes a furnace main body 71, an upper connection portion 72, and a lower connection portion 73, and the upper connection portion 72 is connected to a connection portion P1a provided at the distal end portion of the cleaning gas supply pipe P1. The lower connection portion 73 is connected to the upper connection portion 82 of the lower pyrolysis furnace 62.

  The furnace body 71 includes an inner cylinder 71a made of alumina, a heating part 71b made of an electric resistance heating coil arranged outside the inner cylinder 71a, a heat insulating layer 71c arranged outside the heating part 71b, It includes an outer cylinder 71d disposed outside the layer 71c, and an upper end plate 71e and a lower end plate 71f that hold the inner cylinder 71a and the like in a sandwiched manner. The upper end plate 71e and the lower end plate 71f With the inner cylinder 71a and the like being sandwiched, bolts and nuts are fastened as shown in FIG. Further, through holes 71g having the same diameter as the inner cylinder 71a are formed at locations corresponding to the inner cylinder 71a of the upper end plate 71e and the lower end plate 71f.

  Inside the inner cylinder 71a, although not clearly shown, a baffle group configured in the same manner as shown in FIG. 3 is arranged.

  The output of the heating unit 71 b is adjusted so that the cleaning gas can be decomposed at a high temperature of 1100 ° C. to 1200 ° C.

  The upper connecting portion 72 includes an upper flange 72a and a connecting pipe 72b that connects the upper flange 72a and the upper end plate 71e, and the upper flange 72a of the connecting portion P1a provided at the tip of the cleaning gas. It is connected to the companion flange P1b. This connection is made by, for example, clip fastening in order to facilitate joining / detaching. The connecting pipe 72b communicates with the inner cylinder 71a through a through hole 71g provided in the upper end plate 71e.

  The lower connecting portion 73 includes a lower flange 73a and a connecting pipe 73b that connects the lower flange 73a and the lower end plate 71f. The lower flange 73a is connected to the upper flange 82a of the lower pyrolysis furnace 62. . This connection is made by, for example, clip fastening in order to facilitate joining / detaching. Although the lower flange 73a is not clearly shown, it is water cooled by a water cooling jacket provided on the lower flange 73a. The connecting pipe 73b communicates with the inner cylinder 71a through a through hole 71g provided in the lower end plate 71f. In the figure, reference numerals 74 and 75 denote an inlet and an outlet of the cooling water, respectively.

  The lower pyrolysis furnace 62 includes a furnace body 81, an upper connection part 82, and a lower connection part 83. The upper connection part 82 is connected to the lower flange 73a of the upper pyrolysis furnace 61 as described above, and The lower flange 83a of the connection portion 83 is connected to the upper flange 63a of the process gas discharge portion 63.

  The furnace body 81 includes an inner cylinder 81a made of alumina, a heating part 81b made of an electric resistance heating coil arranged outside the inner cylinder 81a, a heat insulating layer 81c arranged outside the heating part 81b, It includes an outer cylinder 81d disposed outside the layer 81c, and an upper end plate 81e and a lower end plate 81f that hold the inner cylinder 81a and the like in a sandwiched manner. The upper end plate 81e and the lower end plate 81f With the inner cylinder 81a and the like sandwiched, bolts and nuts are fastened as shown in FIG. Further, through holes 81g having the same diameter as the inner cylinder 81a are formed at locations corresponding to the inner cylinder 81a of the upper end plate 81e and the lower end plate 81f.

  The output of the heating unit 81b is adjusted so that the process gas can be decomposed at a medium temperature of 600 ° C to 800 ° C.

  The upper connecting portion 82 includes an upper flange 82a and a connecting pipe 82b that connects the upper flange 82a and the upper end plate 81e. The upper flange 82a is the lower flange 73a of the upper pyrolysis furnace 61 as described above. Connected. This connection is made by, for example, clip fastening in order to facilitate joining / detaching. The connection pipe 82b communicates with the inner cylinder 81a through a through hole 81g provided in the upper end plate 81e, and a branch pipe 82c connected to the process gas supply pipe P2 is branched from the middle. . A flange 82d for connection to the process gas supply pipe P2 is provided at the tip of the branch pipe 82c.

  The lower connecting portion 83 includes a lower flange 83a and a connecting pipe 83b that connects the lower flange 83a and the lower end plate 81f, and the lower flange 83a is connected to the upper flange 63a of the processing gas discharge portion 63. . This connection is made by, for example, clip fastening in order to facilitate joining / detaching. Although the lower flange 83a is not clearly shown, it is water cooled by a water cooling jacket provided on the lower flange 83a. The connecting pipe 83b communicates with the inner cylinder 81a through a through hole 81g provided in the lower end plate 81f. In the figure, reference numerals 84 and 85 denote an inlet and an outlet of the cooling water, respectively.

  The processing gas discharge part 63 includes an upper flange 63a, a lower flange 63b, and a connection pipe 63c that connects the upper flange 63a and the lower flange 63b. The upper flange 63 a is connected to the lower flange 83 a of the lower pyrolysis furnace 62, and the lower flange 63 b is connected to a phase flange of a connection portion provided in the cleaning water storage tank 5. Although the upper flange 63a is not clearly shown, it is water cooled by a water cooling jacket provided on the upper flange 63.

  The connecting pipe 63c is formed in a reducer shape in which the diameter of the lower part is made small, and the reaction product accumulation preventing device 15 is disposed inside the connecting pipe 63c.

  Thus, in Embodiment 2, since the thermal decomposition furnace 60 has a tandem structure and the configuration thereof is simplified, cost reduction and maintenance are easy. For example, the inspection and replacement cycle of the upper heat decomposition furnace 61 and the lower heat decomposition furnace 62 can be made different, and the maintainability is improved.

  The present invention can be applied to heating and decomposition of cleaning gas, process gas, etc. used in semiconductor manufacturing equipment.

1 is a schematic diagram of an exhaust gas treatment system according to Embodiment 1 of the present invention. It is a schematic block diagram of the system. It is the schematic of the secondary processing unit of the embodiment. It is the schematic of the secondary processing unit of the exhaust gas processing system which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary processing unit 2 Secondary processing unit 3 Primary gas cleaning apparatus 4 Secondary gas cleaning apparatus 5 Washing water storage tank 11 Thermal decomposition furnace 12 Water addition apparatus 13 Air supply apparatus 14 Cooling apparatus 15 Decomposition product deposition prevention apparatus 21 Cleaning gas processing unit (processing unit 1)
22 Electromagnetic induction coil (coil part)
23 Process gas processing unit (Processing unit 2)
41 Drainage part 43 Washing water circulation mechanism 60 Thermal decomposition furnace 61 Upper thermal decomposition furnace 62 Lower thermal decomposition furnace 63 Processing gas discharge part S Exhaust gas treatment system P1 Cleaning gas supply pipe P2 Process gas supply pipe

Claims (10)

An exhaust gas treatment system for treating exhaust gases such as cleaning gas and process gas discharged from a semiconductor manufacturing process,
A primary processing unit for removing powder in the process gas, and a secondary processing unit for heating and decomposing exhaust gas,
The exhaust gas characterized in that the secondary processing unit includes a pyrolysis furnace having a first processing unit for heating and hydrolyzing the cleaning gas and a second processing unit for heating and decomposing the process gas. Processing system. The secondary processing unit has a first processing unit and a second processing unit concentrically,
The exhaust gas treatment system according to claim 1, wherein a heating unit including an electromagnetic induction heating coil is disposed between the first processing unit and the second processing unit. The secondary processing unit has a first processing unit and a second processing unit in tandem,
The first processing unit is an upper pyrolysis furnace including a heating unit composed of an electric resistance heating coil,
The exhaust gas processing system according to claim 1, wherein the second processing unit is a lower pyrolysis furnace including a heating unit including an electric resistance heating coil.   The exhaust gas treatment system according to claim 3, wherein the upper pyrolysis furnace and the lower pyrolysis furnace can be joined and detached freely.   The exhaust gas treatment system according to claim 1, further comprising a water addition device for adding moisture to the first treatment unit.   The exhaust gas treatment system according to claim 1, wherein a baffle is disposed in the first treatment unit.   2. The exhaust gas treatment system according to claim 1, wherein the pyrolysis furnace has a decomposition product accumulation prevention device at the bottom.   The exhaust gas treatment system according to claim 1, further comprising a primary gas cleaning device for cleaning the decomposition gas from the secondary processing unit.   9. The exhaust gas treatment system according to claim 8, further comprising a secondary gas cleaning device for cleaning the decomposed gas after cleaning by the primary gas cleaning device. The exhaust gas treatment system according to claim 9, wherein the secondary gas cleaning device includes a gas exhaust part having a cyclone separator.

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