JP3217034B2 - Perfluorinated compound processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating perfluorinated substances, and more particularly to a method for treating perfluorinated substances (hereinafter referred to as PFC) contained in exhaust gas from a semiconductor manufacturing plant. The present invention relates to a method for treating perfluorinated matter and a treatment apparatus suitable for the method.

[0002]

In semiconductor manufacturing processes, CF ₄ or the like as an etching gas in the case of dry etching process, C ₂ F ₆ or the like in the cleaning gas in the case of CVD process, easy PFC handled without harmless explosive to the human body Gas is used. After these PFC gases are introduced into an etching apparatus or a CVD apparatus, they are ionized by high-voltage plasma discharge,
The wafer is etched or cleaned in the state of active radicals. However, the amount of gas actually consumed in etching and cleaning is several to several tens vol%, and the rest is discharged out of the system without reacting.

[0003] Since fluorine atoms have a small atomic radius and a strong bonding force, the compound PFC has stable physical properties.
PFCs are chlorine-free FC (fluorocarbon) and H
FC (hydrofluorocarbon) flon and perfluorinated compounds such as nitrogen trifluoride (NF ₃ ) and sulfur hexafluoride (SF ₆ ) are listed in Table 1. The main PFC names, their physical properties and their use are shown in Table 1.

[0004]

[Table 1]

[0005] PFC does not contain chlorine, has a compact molecular structure and a strong binding force, and thus exists stably in the atmosphere for a long time. For example, CF ₄ is 50,000 years, C ₂ F ₆ is 10,000
0 years, SF ₆ is a long 3,200-year and lifetime. However, the coefficient of warming is large, and CF ₄ is 650 compared to CO _2.
0 times, C ₂ F ₆ is 9,200 times, and SF ₆ is 23,900 times. For this reason, although the amount of emission is smaller than that of CO ₂ which is required to be reduced as a cause of global warming, emission control in the near future is considered to be inevitable. In this case, the current PF
It is important to take measures against exhaust gas at semiconductor manufacturing plants, which account for the majority of C emissions.

In a current semiconductor manufacturing plant, for example, when an etching process is performed, a PF for etching is provided in a chamber.
C gas is supplied, plasma is applied to the PFC, and a part of the plasma is changed to fluorine atoms having a high corrosive action, and the silicon wafer is etched. Exhaust gas in the chamber is continuously exhausted by a vacuum pump, but nitrogen gas purge is performed to prevent corrosion by acid gas. For this reason, 99% of the composition of the exhaust gas is nitrogen, and the remaining 1% is PFC not used for etching. Exhaust gas passing through a vacuum pump is led to an acid duct to remove acid gas,
It is released into the atmosphere including PFC.

As a conventional PFC decomposition technique, a chemical method and a combustion method are in practical use. The former is a method in which fluorine is chemically fixed at about 400 to 900 ° C. by using a special agent. Since no acidic gas is generated due to decomposition, exhaust gas treatment is unnecessary. The latter introduced PFC gas to the combustor and burned LPG and propane at about 1,000 ℃.
Thermally decomposes in the above flame.

[0008]

With the conventional PFC decomposition technology, the chemical method cannot reuse chemicals that have chemically reacted with PFCs, so that expensive chemicals consumed as consumables are frequently replaced. The operating cost is 10-2 of the incineration method.
It becomes 0 times. Further, the amount of the chemical is required in proportion to the PFC gas to be treated, and the practical device scale is about 3 to 5 m ^{2 in the} installation area.
And big.

In the combustion method, since the decomposition of C ₂ F ₆ is performed at a high temperature of 1,000 ° C. or more and the decomposition of CF ₄ is performed at a high temperature of 1,100 ° C. or more, a large amount of heat energy is required.
Ox and a large amount of CO ₂ are also generated. Further, PFC in a semiconductor manufacturing process is diluted with an inert N ₂ gas and discharged, so that a misfire potential is high and sufficient operation management is required.

Consider the application of the combustion method to the semiconductor manufacturing process. PFC is a few percent diluted with N ₂ gas
Since it is discharged as a mixed gas of a concentration, a large amount of combustion air is required together with fuel gas for the combustion of this mixed gas,
As a result, the processing gas amount increases, so that the apparatus scale is large and the installation area is about 0.7 to ⁵ m ² .

For example, 100 from a semiconductor manufacturing process
When 1% of C ₂ F ₆ is contained in the liter / min exhaust gas, the amount of L required to reach the pyrolysis temperature of 1,000 ° C. or more is required.
PG is 10 liters / min, and the required amount of air is about 400 liters / min when the excess ratio is 1.5. The total amount of exhaust gas after combustion consumes oxygen in the air and reduces CO ₂ by 30.
About 500 liters / mi
n, which is about five times the amount of gas from the manufacturing process. In addition, since a semiconductor manufacturing factory is a clean room, the space is greatly restricted, and it is not easy to secure a space particularly when newly installing a processing apparatus in an existing factory.

On the other hand, although the chemical composition is similar to that of PFC, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) which have ozone depleting action are used.
For CFCs, a catalytic system which starts decomposition at about 400 ° C. has been put to practical use. Since CFCs and HFCs contain chlorine having a large atomic radius in the composition, the molecular structure bonded to fluorine or hydrogen having a small atomic radius becomes distorted, and thus decomposition at a relatively low temperature becomes possible.

However, since PFC does not contain chlorine, has a compact molecular structure and a strong binding force, its decomposition temperature is about 70%.
As high as 0 ° C., this catalyst system could not be applied. Recently,
The present inventors have succeeded in developing an alumina-based catalyst having a reaction temperature of about 700 ° C. and applicable to the decomposition of PFC, and have filed prior applications (Japanese Patent Application Nos. 9-4349 and 9-134). No. 163717).
The present invention has been made by applying this catalyst to exhaust gas treatment.

It is an object of the present invention to provide a method for treating perfluorinated substances and a treating apparatus thereof, which can improve the decomposition reaction using a catalyst.

[0015]

SUMMARY OF THE INVENTION A first feature of the present invention is to remove silicon from an exhaust gas containing perfluoride and silicon,
Thereafter, an exhaust gas containing perfluoride, to which one of water and steam is added, is supplied to the catalyst layer filled with the catalyst,
It consists in decomposing perfluorinated compounds with a catalyst. In the first invention, since silicon is previously removed from the exhaust gas supplied to the catalyst, solid particles generated by a reaction between water (or steam) added to the exhaust gas and silicon in the exhaust gas form porous particles formed in the catalyst. Blocking can be prevented. Also,
The first invention can also prevent solid particles from closing the gap formed between the catalysts. For this reason, the first invention can effectively utilize the surface area of the catalyst, and can improve the decomposition reaction of perfluoride. The first invention can improve the decomposition efficiency of perfluorinated compounds.

A feature of the second invention is that the heating is performed so that the temperature of the exhaust gas becomes 650 ° C. or higher. Preferably, since an alumina catalyst is used, perfluorinated compounds can be efficiently and easily decomposed at a reaction temperature of 650 to 750 ° C.

A feature of the third invention is to remove an acid gas from the cooled exhaust gas. This significantly reduces the amount of acidic gas contained in the exhaust gas.

A feature of the fourth invention is that the removal of silicon from the exhaust gas is performed using a first silicon removing device and a second silicon removing device, and the exhaust gas discharged from the first silicon removing device is removed by a second silicon removing device. The water is supplied to the removal device, and the water and the exhaust gas are brought into contact in the second silicon removal device. In the first silicon removal device, the exhaust gas, the wastewater discharged from the first silicon removal device, and the exhaust gas containing the decomposition gas are removed. It is to contact the mixed water of the cooled cooling water.

In the first silicon removing device, the mixed water of the cooling water contacted with the waste gas and the exhaust gas containing the decomposition gas discharged from the first silicon removing device is brought into contact with the exhaust gas containing silicon. Part of the contained silicon is removed by the mixed water. For this reason, the amount of fresh water supplied into the second silicon removing device is reduced, so that the amount of treated wastewater is reduced. Further, since the silicon contained in the exhaust gas is removed by the first silicon removing device and the second silicon removing device, the efficiency of removing silicon contained in the exhaust gas is improved.

[0020] Preferably, the heater, the reactor and the cooling device are integrated so as to reduce the size and reduce the heat loss. Further, preferably, the baffle member has a horizontal structure in which these are arranged in a horizontal direction, and a baffle member for blocking the flow of undecomposed perfluoride is provided above the catalyst layer of the reactor. As a result, the catalyst sinks downward with the passage of time, and it is possible to shut off the gas passing through the void formed above the catalyst layer.

Further, preferably, a heat exchanger for exchanging heat between the exhaust gas containing the decomposed gas and the reaction water is provided between the reactor and the cooling device. Thereby, the heating energy and the amount of cooling water can be reduced by half.

The above-mentioned PFC processing apparatus is applied as an apparatus for processing exhaust gas after a dry etching step or a CVD cleaning step in a semiconductor manufacturing plant, so that efficient PFC decomposition processing can be realized. Also, an outlet of the PFC processing device,
Or measure the concentration of PFC in the exhaust gas at the inlet and outlet,
Management means for monitoring the processing status is provided to check the soundness of the processing and the timing of catalyst replacement. Further, the above integration,
In particular, by arranging a horizontal PFC processing apparatus in a duct area of a semiconductor manufacturing factory, it is possible to solve a space problem when the apparatus is installed in an existing factory.

The PFC used in the present invention is a perfluorinated compound which does not contain chlorine, such as FC and HFC flon, nitrogen trifluoride (NF ₃ ) and sulfur hexafluoride (SF ₆ ). Specifically, it refers to perfluorinated compounds shown in Table 1 used in semiconductor manufacturing plants.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, PF using the catalyst of the present invention will be described.
A plurality of embodiments of the C processing apparatus applied to the treatment of exhaust gas from a semiconductor manufacturing process will be described in detail. Throughout the drawings of each embodiment, the same components are denoted by the same reference numerals.

Embodiment 1 FIG. 1 shows that CF ₄
1 shows a PFC processing apparatus for decomposing and removing PFC. P of this embodiment
The FC processing apparatus 1 is a front spray 1 for injecting water for removing impurities to exhaust gas containing an etching gas (CF ₄ ) from a semiconductor manufacturing process having a dry etching step.
1, a heater 12 for introducing and heating exhaust gas and water, a reactor 13 for filling the catalyst layer 14 and hydrolyzing CF ₄ , a cooling device 16 for cooling the decomposition gas and dissolving CO _{2 and the} like in water,
It comprises a removing device 17 for removing acidic gas in the exhaust gas. Hereinafter, the processing process of the heater 12, the reactor 13, and the cooling device 16 may be particularly referred to as a PFC decomposition processing unit.

The exhaust gas from the semiconductor manufacturing process contains about 1 vol% of C not consumed in the etching process.
Along with F ₄ , SiF _{4 and the} like generated by etching are included as impurities. In order to prevent the catalyst layer 14 from being clogged and deteriorated by the impurities, the exhaust gas that has passed through the vacuum pump 21 is supplied through a pipe 3 through a front spray (silicon remover) 1.
Introduced in 1. Water supplied from the pipe 37 is continuously injected into the container of the pre-spray 11 by the spray 2, and SiF _{4 in} the exhaust gas is converted into SiO 2 by the reaction of the formula (1).
Decomposed into ₂ and HF.

SiF ₄ + 2H ₂ O → SiO ₂ + 4HF (1) Since SiO ₂ is solid fine particles, it is removed from the exhaust gas by water sprayed at the same time as generation. HF,
Because of its high solubility in water, it can be similarly removed from exhaust gases. SiO ₂ and HF discharged from the front spray 11
Is discharged to the bottom of the removing device (acid gas removing device) 17 through the pipe 75 and is treated as waste liquid. The removal of the impurities accompanying the exhaust gas may be carried out by bubbling instead of spraying.

The exhaust gas containing CF ₄ from which impurities have been removed is mixed with reaction water (or steam) supplied from a pipe 35 and introduced into the heater 12 through the pipe 4.
The supply of water (or steam) into the exhaust gas depends on the catalyst layer 14.
The reaction of CF ₄ in is because the hydrolysis by CF ₄ and H ₂ O. The supply flow rate of the reaction water (or steam)
It is about 25 times per mole of CF ₄ .

The heater 12 is activated by the electric heater 32 so that the decomposition of CF _{4 in} the catalyst layer 14 starts at about 7 ° C.
Heat the exhaust gas to a temperature of 00 ° C. Temperature control device 30
Adjusts the current of the electric heater 32 based on the exhaust gas temperature Te measured by the thermometer 31 disposed at the inlet of the reactor 13, and controls the temperature so as to maintain the reaction temperature in the catalyst layer 14. For CF _4, it is heated to about 650 to 750 ° C..

The exhaust gas containing the heated CF ₄ is supplied to a reactor 13 filled with a catalyst. The catalyst layer 14 is filled with an alumina (Al ₂ O ₃ ) -based catalyst described later, and CF ₄
Reacts with H ₂ O as shown in equation (2) to be decomposed into HF and CO ₂ .

CF ₄ + 2H ₂ O ⇒ CO ₂ + 4HF (2) When the PFC contained in the exhaust gas is C ₂ F ₆ ,
It reacts as in equation (3) to decompose into CO ₂ and HF.

C ₂ F ₆ + 2H ₂ O ⇒ 2CO ₂ + 6HF (3) FIG. 2 shows the decomposition characteristics of PFC by the alumina catalyst. The horizontal axis indicates the reaction temperature, and the vertical axis indicates the decomposition rate. This property is
This is an example of the above-mentioned prior application, and the composition of the catalyst used is 80% Al ₂ O _{3 and} 20% NiO ₂ . The test gases include four kinds of PFs, CHF ₃ , CF ₄ , C ₂ F ₆ and C ₄ F _8.
C was used. The test conditions were as follows: PFC gas concentration 0.5%, S
V is 1000 / h. About 10 times the theoretical value was added as reaction water. As shown in FIG. 2, nearly 100% decomposition was obtained at a reaction temperature of about 700 ° C. for all four PFCs. The decomposition rate of CF ₄ and CHF ₃ is 95% or more at about 650 ° C., and that of C ₂ F ₆ and C ₄ F ₈ is 80% or more at about 670 ° C. According to this catalyst, PFC can be practically decomposed at a reaction temperature of about 650 to 750 ° C.

The high-temperature exhaust gas containing the decomposition gases CO ₂ and HF discharged from the catalyst layer 14 is supplied to the cooling device 16.
The temperature is cooled to 100 ° C. or lower by water continuously supplied by the sprays 6 and 7 of FIG. The supply of the cooling water to the sprays 6 and 7 is performed by pipes 38 and 39. Instead of spraying, high-temperature exhaust gas may be bubbled into the water tank for cooling. Further, an alkaline solution may be supplied from the sprays 6 and 7 instead of water. A part of the HF is absorbed and removed by the cooling water jetted from the sprays 6 and 7. The waste liquid discharged from the cooling device 16 is supplied to pipes 8 and 7
5 leads to the bottom of the removal device 17.

[0034] The removal device 17 contains about 4 vol%
In order to remove the high concentration of HF contained therein, water is continuously supplied from the spray 36 to the packed layer 10 filled with plastic lahiscilling, and the HF is reduced to 4% by sufficiently contacting the water and the decomposition gas. To several ppm. The supply of water to the spray 36 is performed by a pipe 76. The detoxified decomposed gas is discharged out of the system through a pipe 43 via an exhaust fan 22.

The inside of the cooling device 16 and the removing device 17 is maintained at a negative pressure by the exhaust fan 22 to prevent HF and the like contained in the exhaust gas from leaking out of the system. The removing device 17 can also use a bubbling method. However, the spray method or packed tower method has lower pressure loss,
The size of the exhaust fan can be reduced.

On the other hand, the front spray 11, the cooling device 16,
The waste liquid containing impurities and HF discharged from the removing device 17 is guided to a neutralization treatment device (not shown) through a pipe 42 by driving a drain pump 23, and is subjected to waste water treatment.

In this embodiment, the silicon contained in the exhaust gas is SiO ₂ in the front spray 11 which is a silicon remover.
Therefore, solid particles such as SiO ₂ are not carried into the catalyst layer 14 of the reactor 3. Front spray 1
When 1 is not installed, the water supplied from the pipe 35 causes the reaction of the formula (1) downstream of the junction of the pipe 4 and the pipe 35 to generate SiO ₂ . This S
When iO ₂ flows into the catalyst layer 14, the following problems occur. SiO ₂ plugs the porous formed in the catalyst. Close the gap formed between the catalysts.
As a result, the surface area of the catalyst decreases, and the decomposition reaction of PFC decreases. In addition, the flow of exhaust gas between the catalysts becomes worse due to the above, and the contact between the catalyst and the exhaust gas is hindered. This also leads to a reduction in the decomposition reaction of PFC. In the present embodiment, since the reaction of the formula (1) is forcibly generated in the front spray 11 to remove SiO ₂ from the exhaust gas in advance, the above-mentioned problem does not occur, and the efficiency of PFC decomposition can be improved. In the present embodiment, PFC decomposition treatment can be realized with high efficiency using a catalyst, and emission of PFC, which is one of the gases causing global warming, to the atmosphere can be avoided.

According to this embodiment, CF ₄ can be decomposed at a temperature sufficiently lower than that of the conventional combustion system, and utilities such as heat energy and water can be reduced. In the case of a semiconductor factory, a low decomposition gas temperature is also advantageous in terms of fire safety. In addition, since the catalyst has a long life and can be reused, the operating cost can be greatly reduced as compared with the chemical method.

Although the above embodiment is directed to the case where the semiconductor factory employs CF ₄ as the processing gas for the etching process, the present invention is not limited to this. For example, an exhaust gas when C ₂ F ₆ is used as a cleaning gas by CVD can be treated with the same configuration. In addition, the PFC shown in Table 1 can be treated at the same configuration and at a reaction temperature of about 700 ° C.

Embodiment 2 FIG. 3 shows a PFC decomposition processing section in which the PFC decomposition processing section of Embodiment 1 is integrated.
Heater 12, reactor 13, cooling device 16, and heat exchange chamber 1
5 are integrally connected by flange portions 121, 131 and 161. The heater 12, the reactor 13, and the heat exchange chamber 15 are equipped with heat insulating materials 122, 132, and 152, respectively. According to the PFC decomposition processing unit, the processing device can be downsized, and the responsiveness of control by the temperature control device 30 can be improved. Further, heat loss can be reduced as compared with a case where pipes are connected between devices. Note that an integrated configuration without the heat exchange chamber 15 may be used.

In a semiconductor manufacturing plant, the entire building is a clean room in which the air-conditioning is controlled. Therefore, in order to reduce the floor area of the whole plant, it is desired to reduce the installation space of the equipment. According to the PFC decomposition processing section in this embodiment, a PFC gas processing apparatus having an exhaust gas processing capacity of about 100 liter / min containing about 1% of CF ₄ has an installation area of about 0.4 m ² . This is a fraction of the installation area assuming that the combustion method and the chemical method are adopted.
It is about 1/10.

Further, in the present embodiment, a heat exchange chamber 15 for effectively utilizing the heat of the exhaust gas of about 700 ° C. discharged from the reactor 13 is provided between the reactor 13 and the cooling device 16. In the heat exchange chamber 15, a heat transfer tube 151 connected to a pipe 35 for supplying reaction water is provided. The reaction water becomes steam in the heat transfer tube 151, and the steam is led to the inlet side of the heater 12 by the pipe 153.

FIG. 4 shows a PFC processing apparatus 1C to which the PFC decomposition processing unit having the integrated structure shown in FIG. 3 is applied.
Low-temperature reaction water (supplied by the pipe 35) flows into the inlet of the heat transfer tube 151. This reaction water is supplied to the heat exchange chamber 15 for about 7
The heat is exchanged with the exhaust gas at 00 ° C., and the steam is converted into steam at 100 ° C. or higher and introduced into the heater 12 through the pipe 153. On the other hand, the exhaust gas is cooled to about 300 ° C. or lower by the heat exchange and guided to the cooling device 16. Since heat exchange is performed between the reaction water and the high-temperature decomposition gas, heat energy can be recovered, and the energy required for heating and the amount of water required for cooling can be reduced by half.

[Embodiment 3] FIG. 5 shows an exhaust gas management system of a semiconductor manufacturing plant to which the PFC processing apparatus 1 is applied. The PFC processing apparatus 1 is connected to each of three dry etching apparatuses 5. The gas chromatograph 40 measures the concentration of PFC, for example, CF ₄ , in the exhaust gas collected from the inlet side and the outlet side of each PFC treatment device 1, and transmits each measured value to the monitoring device 45. Incidentally, the acid gas removal filter 4 7 is provided in the gas sampling tube 46A from the inlet side.

This system will be described specifically. Each dry etching apparatus 5 has a CFC, which is a kind of PFC gas, inside.
By supplying F ₄ as the etching gas is performed each etching process on the wafer. Exhaust gas from each dry etching apparatus 5 reaches the pipe 3 through the pipes 44A and 44B by driving the vacuum pumps 21A and 21B.
It is led to the corresponding PFC processing device 1. The exhaust gas is
About 1% by volume of CF not consumed in the etching process
₄ , and SiF ₄ generated by etching. After the exhaust gas is processed by the PFC processing apparatus 1, the exhaust gas is exhausted to an acid duct (exhaust duct) 25 through a pipe 43. A part of the exhaust gas in the pipe 3 is guided to the gas chromatograph 40 by the gas sampling pipe 46A and the acid gas removal filter 47, respectively. The exhaust gas in the pipe 43 is also led to the gas chromatograph 40 by the gas sampling pipe 46B. Exhaust gas supplied to each PFC treatment device 1 and CF ₄ in the exhaust gas discharged from each PFC treatment device 1
The concentration is measured by the gas chromatograph 40.
The monitoring device 45 inputs the measured value of the CF ₄ concentration from the gas chromatograph 40. The monitoring device 45 includes a certain pipe 43
When the CF ₄ concentration in the PFC processing device 1 is higher than the first set value, the alarm 51
Generates an alarm while blinking. Monitoring device 45
When the CF ₄ concentration in a certain pipe 3 is higher than the second set value, an alarm sound is emitted while blinking the alarm 50 of the corresponding dry etching apparatus 5 to notify the occurrence of an abnormality.

In the present embodiment, the PFC concentration in the exhaust gas supplied to the PFC treatment apparatus 1 and the PFC concentration discharged from the outlet of the exhaust gas without decomposition are measured for each apparatus 5. This result of the monitoring device 4 5 outlet exhaust processing device 1 PF
The C concentration is monitored, and a display or alarm is output when the target value is not satisfied. Further, the soundness of the catalytic reaction or the replacement time due to the catalyst deterioration is checked based on the decomposition rate depending on the PFC concentration on the inlet side and the outlet side of the PFC treatment apparatus 1.

[Embodiment 4] FIG. 6 shows a layout of a semiconductor manufacturing plant. The building 59 of the semiconductor manufacturing factory
Clean rooms 53 and 54 are provided both above and below the grating 52. The air in the clean room 54 is supplied to the filter 55 by driving the blowers 55A and 55B.
A and 55B purify and are led to the clean room 53 by piping 57A and 57B. This air is purified again by the filter 58. Clean room 53 is clean room 5
Cleaner than 4 Dry etching equipment 5
Is installed in a clean room 53 which is a manufacturing apparatus area. The clean room 54 includes the vacuum pumps 21A, 21
An auxiliary machine area 103 where B and the like are installed, and a pipe duct area 102 through which pipes and ducts pass.

In this embodiment, two PFC processing apparatuses 1 ′ are arranged in the duct area 102. Duct area 10
2 is provided with an acid duct 25, and an exhaust gas containing an acid gas is supplied to the acid duct 25 by an acid gas treatment device (not shown).
It is guided and processed. Therefore, the PFC treatment apparatus 1 ′ of the present embodiment omits the last removal device 17 of the PFC treatment apparatus 1 described above, and removes the exhaust gas containing HF and the like after cooling.
The air is directly exhausted to the acid duct (exhaust duct) 25.

According to this, even in an existing semiconductor manufacturing plant where it is difficult to secure a space, it becomes easy to install the PFC processing apparatus. In this case, since the duct area 102 generally has a small height, if the PFC processing apparatus 1 ′ can be elongated horizontally as shown in the figure, the duct area 102
Often, it is easier to arrange them.

FIG. 7 shows the structure of a horizontal PFC processing apparatus 1 '. In contrast to the vertical structure shown in FIG. 3, each device is arranged horizontally and integrated. If the spray flow of the front spray 11 and the cooling device 16 is performed from top to bottom, there is no functional change even in the horizontal arrangement. However, when the catalyst layer 14 is in the horizontal direction, the catalyst slightly settles out after a lapse of time to form a gap above the catalyst layer 14, and an undecomposed gas to be processed (PFC gas) passes through the gap. There is fear. Therefore, a baffle plate 141 is provided above the catalyst layer 14. Further, on the inlet side and the outlet side of the reactor 13, holding plates 142 and 143 of perforated plates for suppressing the lateral movement of the catalyst are provided. As shown in FIG. 7 (b), a fan-shaped baffle 141 is formed on the catalyst layer 14 on the cylinder.
And the height of the sector can cover the maximum gap width due to settlement. Even if a gap is formed above the catalyst layer 14 during operation, the baffle plate 141 can block gas passing therethrough, and all the gas to be treated passes through the catalyst layer 14 and is decomposed.

According to this embodiment, in an existing semiconductor factory where there is not enough space for disposing devices, the installation of the PFC processing apparatus is facilitated by using the piping duct area 102, and a near-field device for preventing global warming is provided. It can respond to future exhaust gas regulations. Note that the vertical type (FIG. 3) and the horizontal type (FIG. 7) of the PFC processing apparatus are appropriately selected according to the circumstances of the space at the application place.

[Embodiment 5] In another embodiment of the present invention, P
FIG. 8 shows the FC processing apparatus 1B. PFC processor 1B
Is a device in which the front spray 11 of the PFC treatment device 1 is replaced with a silicon removal device 11A which is a front spray, and a return pipe 60 is newly provided. The silicon removing device 11A includes silicon removers 11B and 11C. Silicon remover 1
1B installs spray 2A in a container. The silicon remover 11 </ b> C installs the spray 2 </ b> B and the diffusion unit 59 in which the filler is spread in the container. Silicon remover 11B and
The 11C container is made of corrosion resistant vinyl chloride to prevent corrosion by HF. The return pipe 60
Downstream of the drain pump 23, it is connected to the pipe 42, and is also connected to the spray 2B. Piping 37 is spray 2
A is connected.

Exhaust gas containing impurities such as CF ₄ and SiF ₄ is discharged into the vessel of the silicon remover 11C through the pipe 3. The exhaust gas rises in the container and spreads in the diffusion section 5.
9 to diffuse and flow in the container. Part of the drainage discharged from the drain pump 23 is returned to the return pipe 60.
Is sprayed from the spray 2B. The concentration of F ions and Si ions in the waste water discharged from the drain pump 23 is several tens ppm or less. This wastewater has a sufficient performance of removing Si and HF. Due to the contact between some SiF ₄ contained in the exhaust gas and the sprayed wastewater,
The reaction of the formula (1) occurs. The generated SiO ₂ is removed from the exhaust gas by wastewater. HF dissolves in the wastewater.

The exhaust gas discharged from the silicon remover 11C is led to the silicon remover 11B. Fresh water supplied from the pipe 37 is supplied from the spray 2A to the silicon remover 11.
It is injected into B. In the silicon remover 11B, the reaction of the formula (1) occurs due to the contact between the sprayed water and the SiF ₄ remaining in the exhaust gas. The drainage liquid of the silicon remover 11B containing SiO ₂ and HF is supplied to the silicon remover 11C.
To the bottom of the removing device 17 through the pipe 41 together with the drainage sprayed from the spray 2B. The processing in other parts of the PFC processing apparatus 1B is the same as the processing in the PFC processing apparatus 1.

The PFC decomposition processing section of the PFC processing apparatus 1B has a configuration in which the PFC decomposition processing section of the PFC processing apparatus 1 is integrated. The configuration of the PFC decomposition processing unit of the PFC processing device 1B will be described with reference to FIG.

The PFC decomposition processing section in this embodiment is one in which the heater 12, the reactor 13, and the cooling device 16 are integrated. The casing 62 and the inner tube 63 are
And the reactor 13. The inner diameter of the inner tube 63 is smaller at the upper part than at the lower part. The flange 66 of the inner tube 63 is fixed to the flange 68 of the casing 62 with a bolt. Heater 1
2 and the reactor 13 have an integral structure. The annular plate 64 is the inner pipe 6
3 installed on the top. The heater 12 is located above the annular plate 64 and includes the electric heater 32 and a heat insulating material 122 covering the electric heater 32. A gap 73 is formed between the casing 62 and the annular plate 64. The gap 73 has a high temperature (7
The heat of the exhaust gas (00 ° C.) is transmitted from the inner tube 63 and the annular plate 64 to the casing 62 and is prevented from being released to the outside. That is, the heat loss of the exhaust gas can be reduced.

The reactor 13 is located below the annular plate 64. The reactor 13 includes a catalyst cartridge 65 having a catalyst layer 14 formed by filling an alumina-based catalyst on a wire mesh 74.
Is provided. Alumina-based catalyst is _{Al 2 O 3 80%, NiO} 2
The catalyst contains 20%. The catalyst cartridge 65 is inserted into the inner tube 63. The cylinder 70 is connected to the casing 62 by connecting the flange 69 to the flange 68.
Attached to. The catalyst cartridge 65 has a flange 6
7 by engaging the flange 6 with the casing 6.
2 is held. The reactor 13 has a heater for keeping heat (not shown) installed between the casing 62 and the inner tube 63. A baffle holding member 71 having a baffle 72
It is attached to the cylinder 70. The cooling device 16 is located below the baffle holding member 71 and is attached thereto.
Air is supplied into the heater 12 by the pipe 61.

The heater 12 and the reactor 13 in this embodiment
The cooling device 16 has the same functions as those of the PFC processing device 1.

The PFC processing apparatus 1B produces the effects obtained by the PFC processing apparatus 1. PFC processing apparatus 1 B, since the amount of fresh water supplied from the water supply pipe 38 is reduced, wastewater led to the neutralization apparatus (not shown) is reduced.
Further, the reaction of the formula (1) is performed by the silicon removing units 11B and 11C.
The removal efficiency of Si components such as SiF ₄ contained in exhaust gas is improved. Further, by installing the baffle 72, the cooling device 1 is removed from within the baffle holding member 71.
Since the passage leading the exhaust gas into the meandering passage 6 meanders, it is possible to prevent the cooling water spray injected from the sprays 6 and 7 from reaching the catalyst layer 14. Therefore, the catalyst layer 1 due to the droplets
Since the temperature drop of 4 can be prevented, the discharge of undecomposed P F C is eliminated.

In the configuration shown in FIG. 8, the return pipe 60 may be directly connected to the bottom of the removing device 17 instead of the pipe 42. In this case, it is necessary to install a pump for supplying the waste liquid to the spray 2B in the return pipe 60. Even in such a configuration, the same effect as the configuration in FIG. 8 can be obtained.

[0061]

According to the first aspect of the present invention, the surface area of the catalyst can be effectively utilized, so that the decomposition reaction of perfluorinated product can be improved and the efficiency of decomposition of perfluorinated product can be improved.

According to the second aspect of the present invention, perfluorinated compounds having a large warming effect can be efficiently and easily decomposed at a reaction temperature of 650 ° C. or higher (preferably 650 to 750 ° C.), thereby suppressing global warming. it can.

According to the third aspect, the amount of acidic gas contained in the exhaust gas can be significantly reduced, and the amount of acidic gas (for example, HF) released into the atmosphere is significantly reduced.

According to the fourth aspect of the present invention, the amount of fresh water used for removing silicon is reduced, so that the amount of wastewater to be treated can be reduced. In addition, since silicon is removed by the first and second silicon removing devices, the removal efficiency of silicon contained in exhaust gas is significantly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a PFC processing apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a decomposition rate of PFC by an alumina-based catalyst.

FIG. 3 shows an example of a PFC decomposition processing unit having an integrated structure (vertical type).
FIG.

FIG. 4 is a configuration diagram of a PFC processing apparatus according to another embodiment of the present invention to which the PFC decomposition processing section of FIG. 3 is applied.

5 is a configuration diagram of an exhaust gas management system of a semiconductor manufacturing apparatus to which the PFC processing apparatus of FIG. 1 is applied.

6 is an explanatory diagram showing a schematic layout of a semiconductor manufacturing plant in which the PFC processing apparatus of FIG. 7 is arranged.

FIG. 7 shows a configuration of a PFC processing apparatus according to another embodiment of the present invention, in which (a) is a schematic longitudinal sectional view of the PFC processing apparatus;
(B) is a longitudinal sectional view in the direction perpendicular to the axial direction of the PFC processing device near the baffle plate (a) of (a).

FIG. 8 is a configuration diagram of a PFC processing apparatus according to another embodiment of the present invention.

FIG. 9 is a detailed configuration diagram of a PFC decomposition processing unit in FIG. 8;

[Explanation of symbols]

1, 1 ', 1C, 1B PFC processing device, 2, 2A, 2
B, 6, 7, 36: spray, 5: dry etching device, 11: front spray, 11A: silicon removal device, 1
1B, 11C: silicon remover, 12: heater, 13: reactor, 14: catalyst layer, 15: heat exchange chamber, 16: cooling device, 17: removing device, 21: vacuum pump, 22: exhaust fan, 23 ... drain pump, 25 ... acid duct, 30 ... temperature controller, 31 ... thermometer, 32 ... electric heater, 40 ... gas chromatograph, 41 ... acid gas removal filter, 60 ...
Return piping, 72: baffle return piping, 101: manufacturing equipment area, 102: piping duct area, 103: auxiliary equipment area, 141: baffle plate, 151: heat transfer pipe.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Mori 3-18-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Ibaraki Hitachi Information Service Co., Ltd. (72) Inventor Hisao Yokoyama 3-chome, Sachimachi, Hitachi City, Ibaraki Prefecture 1 Hitachi Engineering Co., Ltd. (72) Inventor Takayuki Toyama 3-1-2 Bentencho, Hitachi City, Ibaraki Pref. Nitto Kyowa Engineering Co., Ltd. (72) Inventor Toshihide Takano 3-chome, Sachimachi, Hitachi City, Ibaraki Prefecture No. 1-1 Co., Ltd. Hitachi, Ltd., Hitachi Plant (72) Inventor Shin Tamada 3-1-1, Sakaimachi, Hitachi City, Ibaraki Prefecture Co., Ltd. Within Hitachi, Ltd. Hitachi Plant (72) Inventor Shuichi Kanno Omika-cho, Hitachi City, Ibaraki Prefecture 7-1-1-1 Hitachi, Ltd. Hitachi Research Laboratory (56) References JP-A-10-192653 (JP, A) JP-A-10-25 2651 (JP, A) JP-A-11-70322 (JP, A) JP-A-11-244656 (JP, A) US Pat. No. 5,649,985 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B01D 53/86 WPI / L (QUESTEL)

Claims (20)

(57) [Claims] 1. A catalyst filled with a catalyst by removing silicon from an exhaust gas containing perfluorinated substances and silicon and heating the exhaust gas containing perfluorinated substances to which either water or steam is added. The catalyst is used to decompose the perfluoride contained in the exhaust gas by the catalyst ,
Thus, a method for treating perfluorinated substances, which cools the exhaust gas containing the generated decomposition gas . 2. The method of claim 1, wherein the heating is performed so that the temperature of the exhaust gas is 650 ° C. or higher. 3. The method according to claim 2 , wherein said exhaust gas is heated to a temperature in the range of 650 ° C. to 750 ° C. 4. A method of treating excessive fluoride according to claim 1 or claim 2 for removing acid gases from the cooled exhaust gas. Removal of 5. A silicon from the flue gas, the processing method of the perfluorinated compound according to claim 1 carried out by contacting the exhaust gas and the water containing the silicon. 6. The method of claim 5 , wherein the cooling of the exhaust gas containing the decomposition gas is performed by contacting the exhaust gas with cooling water. 7. The removal of silicon from the exhaust gas is performed using a first silicon removal device and a second silicon removal device,
The exhaust gas discharged from the first silicon removal device,
The water was supplied to the second silicon removing device, the water and the exhaust gas were brought into contact in the second silicon removing device, and the exhaust gas was discharged from the second silicon removing device in the first silicon removing device. 7. The method for treating perfluorinated substances according to claim 6 , wherein the waste water and the exhaust gas containing the decomposition gas are brought into contact with the cooling water mixed water. 8. The catalyst according to claim 1, wherein said catalyst is an alumina-based catalyst.
Of perfluorinated compounds. Wherein said exhaust gas either processing method over fluorides of claims 1 to 8 which is exhaust gas discharged from a semiconductor manufacturing device. 10. A silicon removing device for removing silicon from an exhaust gas containing perfluorinated substances and silicon, and a heating device for heating the exhaust gas discharged from the silicon removing device and added with either water or steam. A catalyst layer filled with a catalyst that decomposes the perfluorinated substance contained in the exhaust gas heated by the heating device; and a catalyst layer discharged from the catalyst layer.
And a cooling device for cooling the exhaust gas . 11. A temperature detector for detecting temperature of the exhaust gas supplied to the catalyst layer, according to claim 1 0 comprising a control device for controlling the heating device based on the measured temperature of the temperature detector Perfluoride treatment equipment. 12. The perfluorinated material processing apparatus according to claim 10, further comprising an acid gas removing device for removing an acidic gas contained in said exhaust gas discharged from said cooling device. Wherein said claims water supply pipe for supplying water in contact with the exhaust gas is connected to said silicon remover 1 0
Perfluoride treatment equipment. 14. A perfluorinated water treatment apparatus according to claim 12 , wherein said cooling apparatus comprises a spray apparatus for spraying cooling water for cooling said exhaust gas. 15. The silicon removing device has a first silicon removing device to which the exhaust gas is supplied, and a second silicon removing device to which the exhaust gas discharged from the first silicon removing device is supplied. A drain supply pipe for supplying waste water discharged from the cooling device is connected to the first silicon removing device, a water supply pipe for supplying water is connected to the second silicon removing device, and the first silicon removing device is provided. any of the second claim 1 0, wherein the water is supplied from the second silicon removal apparatus in the silicon removing apparatus, according to claim 12 and claim 14 in
The perfluorinated processing equipment. 16. The apparatus according to claim 1, wherein the heater, the reactor containing the catalyst layer, and the cooling device are integrated in this order.
0 perfluoride treatment equipment. 17. A heat exchanger for performing heat exchange between exhaust gas discharged from the catalyst layer and water and generating the steam is provided between the catalyst layer and the cooling device. 1 0 peracetic fluoride processor. 18. Any over-fluoride treatment apparatus according to claim 1 0 to claims 1-7 wherein the catalyst filled in the catalyst layer is alumina-based catalyst. 19. A silicon removing apparatus for removing silicon from an exhaust gas containing perfluorinated substances and silicon discharged from a semiconductor manufacturing apparatus, and one of water and steam discharged from the silicon removing apparatus is added. A heating device for heating the exhaust gas containing the perfluorinated material, a catalyst layer filled with a catalyst for decomposing perfluoride contained in the exhaust gas heated by the heating device, and a catalyst layer discharged from the catalyst layer. And a cooling device for cooling the exhaust gas. 20. The heater, the reactor containing the catalyst layer, and the cooling device are integrally formed in this order, and the heater, the reactor, and the cooling device, which are integrally formed, are:
20. The exhaust gas treatment apparatus of a semiconductor manufacturing apparatus according to claim 19 , wherein the exhaust gas processing apparatus is installed in a building where the semiconductor manufacturing apparatus is installed.