WO2014129050A1

WO2014129050A1 - Device for processing perfluoro compounds and method for processing perfluoro compounds

Info

Publication number: WO2014129050A1
Application number: PCT/JP2013/083214
Authority: WO
Inventors: 純一鳥巣; 裕二早坂; 正直小野寺
Original assignee: 昭和電工株式会社
Priority date: 2013-02-19
Filing date: 2013-12-11
Publication date: 2014-08-28
Also published as: TW201433350A; JPWO2014129050A1

Abstract

This device (2) for processing perfluoro compounds is provided with: a first heater (221) that heats water and a device entrance exhaust gas that is an etching exhaust gas; a second heater (222) that further heats the water and the device entrance exhaust gas and that generates decomposition gas containing an acidic gas by means of hydrolysis of a perfluoro compound by means of a catalyst; a heat exchanger (231) that exchanges heat between the device entrance exhaust gas and the decomposition gas; and an acid component elimination device (232) that performs dry elimination of the acid component from the decomposition gas. The first heater (221), second heater (222), heat exchanger (231), and acid component elimination device (232) are disposed along any of the sides of a rectangular region and within the rectangular region when seen from above, the device entrance exhaust gas and a discharge gas are respectively led in from and discharged from one of the short sides of the rectangular region, and the second heater (222) is disposed at the other short side of the rectangular region.

Description

Perfluoride treatment apparatus and perfluoride treatment method

The present invention relates to a perfluoride treatment apparatus used to decompose and treat perfluoride, for example.

For example, in the manufacturing process of a semiconductor device or a liquid crystal device, etching or cleaning may be performed to form a fine pattern. In this case, a perfluoride is often used. In addition, since perfluoride is generally stable and often harmless to the human body, it is also used, for example, as a refrigerant for air conditioners.
However, many of these perfluorides have a great impact on the global environment when released into the atmosphere. That is, since it exists stably in the atmosphere for a long time and has a large global warming potential, it can contribute to global warming. As described above, perfluoride is generally stable, and its influence often lasts for a long time.
Therefore, in order not to affect the global environment, it is necessary to decompose the used perfluoride and make it harmless to the global environment and release it into the atmosphere.

Patent Document 1 discloses a gas stream containing a fluorine compound containing only fluorine as a halogen, a catalyst containing Al, such as a catalyst made of Al and Ni, Al and Zn, and Al and Ti in the presence of water vapor. A method for decomposing a fluorine-containing compound is disclosed in which contact is made at about 200 to 800 ° C. to convert fluorine in the gas stream into hydrogen fluoride.
Further, Patent Document 2 includes a perfluoride decomposition apparatus that is provided with a catalyst layer and is supplied with exhaust gas containing perfluoride and decomposes perfluoride, and is included in exhaust gas discharged from the perfluoride decomposition apparatus. There is disclosed a perfluoride treatment apparatus comprising an acidic substance removing device for removing a first reaction product produced by reacting an acidic substance with a Ca salt.

JP 2001-224926 A JP 2008-246485 A

However, when a large amount of gas containing perfluoride is to be processed, the apparatus becomes large, and when HF (hydrogen fluoride) or the like is generated as a reactant, a large amount of water is required to remove HF or the like. It may be necessary. Therefore, there has been a problem that wastewater containing HF must also be treated. In addition, when heating and decomposing perfluoride, safety problems may occur.

The present invention has been made in view of the above-described problems of conventional techniques.
That is, an object of the present invention is to provide a perfluoride treatment apparatus that can treat a large amount of perfluoride, is easy to downsize, has a small amount of discharged wastewater, and is excellent in safety.

Thus, according to the present invention, the first heating means for heating the gas and water containing perfluoride, the gas and water containing the perfluoride heated by the first heating means are further heated and predetermined. A second heating means for hydrolyzing the perfluoride with the prepared catalyst to generate a cracked gas containing an acidic gas, a first stage of the first heating means and a rear stage of the second heating means, Heat exchange means for mixing water with the gas containing perfluoride before flowing into the heating means and exchanging heat with the cracked gas after flowing out from the second heating means, and outflow from the heat exchange means An acid component removing means for dry-removing the acid component from the later cracked gas, and the first heating means, the second heating means, the heat exchange means and the acid component removing means are rectangular regions when viewed from above. One of the rectangular regions inside The gas containing perfluoride flowing along the section and flowing into the first heating means and the exhaust gas after flowing out from the acid component removing means are introduced and discharged from one short side of the rectangular region, respectively. The second heating means is provided on the other short side of the rectangular region, and a perfluoride treatment apparatus is provided.

Here, the first heating means is arranged side by side with the second heating means on the other short side of the rectangular area, and the heat exchange means and the acid component removing means are along the long side of the rectangular area, It is preferable to arrange the exhaust gas in order in the direction where the exhaust gas flows out.
A pretreatment means for removing solids and / or mist from the gas containing perfluoride; and a posttreatment means for removing solids from the exhaust gas after the acid component has been dry removed by the acid component removal means. The pretreatment means further comprises a long side different from the long side where the heat exchanging means and the acid component removing means are arranged, and the portion between the portion where the gas containing perfluoride flows and the first heating means. The post-treatment means is preferably arranged on the long side where the heat exchange means and the acid component removal means are arranged, and between the acid component removal means and the location where the exhaust gas flows out.

Further, the apparatus further comprises a medicine supply means for supplying a medicine for dry removal of the acid component from above the acid component removal means, and a medicine discharge means for discharging the medicine from below the acid component removal means. The cracked gas to be introduced is preferably introduced from below the acid component removing means and discharged from above the acid component removing means.
Furthermore, it is preferable that the water and / or device driving air mixed by the heat exchange means is supplied from one short side of the rectangular region.

Further, according to the present invention, the first heating step for heating the gas and water containing perfluoride, the gas and water containing the perfluoride heated by the first heating step are further heated, and predetermined. A second heating step of hydrolyzing the perfluoride with the prepared catalyst to generate a cracked gas containing an acidic gas, and a first heating step before the first heating step and after the second heating step. A heat exchange step in which water is mixed with a gas containing perfluoride before flowing into the gas and heat exchange is performed with the cracked gas after flowing out from the second heating step, and after flowing out from the heat exchange step An acid component removal step for dry-removing the acid component from the cracked gas, and the first heating step, the second heating step, the heat exchange step, and the acid component removal step are performed inside the rectangular region when viewed from above. Along any side of the rectangular area The gas containing perfluoride flowing into the heat exchange process and the exhaust gas after flowing out from the acid component removal process are introduced and discharged from one short side of the rectangular region, respectively, in the second heating process Is provided at a position on the other short side of the rectangular region. A method for treating perfluoride is provided.

The first heating means, the second heating means, the heat exchange means, and the acid component removing means are disposed along the side of any of the rectangular areas inside the rectangular area when viewed from above, The gas containing perfluoride flowing into one heating means and the exhaust gas after flowing out from the acid component removing means are introduced and discharged from one short side of the rectangular area, respectively, and the second heating means is a rectangular area It is possible to improve safety by being arranged on the other short side, and to arrange other devices such as a heat exchanger and an acid component removing device in order between the long sides of the rectangular region. This makes it easier to miniaturize the device.

Safety can be further improved by arranging the 1st heating means along with the 2nd heating means along the other short side of a rectangle field.
Further, the heat exchange means and the acid component removal means are arranged in order along the long side of the rectangular region toward the location where the exhaust gas flows out, and the pretreatment means is a length in which the heat exchange means and the acid component removal means are arranged. A long side that is different from the side and is arranged between a portion into which a gas containing perfluoride flows and the first heating means, and the post-processing means is arranged with the heat exchange means and the acid component removing means. By being arranged between the acid component removal means and the location where the exhaust gas flows out on the long side, each device is arranged in a substantially U shape in the order in which the gas flows. Therefore, for example, as compared with a case where the devices are arranged in a straight line, the length occupied by the perfluoride treatment apparatus when viewed from above is reduced and the area is also reduced.

The apparatus further comprises a medicine supply means for supplying a medicine for dry-removing the acid component from above the acid component removal means, and a medicine discharge means for discharging the medicine from below the acid component removal means, which are introduced into the acid component removal means. The decomposition gas is introduced from below the acid component removing means and discharged from above the acid component removing means, so that the medicine can be exchanged by a simple system and the consumption of the medicine can be reduced. it can.

Water and equipment driving air mixed by the heat exchange means are supplied from one short side of the rectangular area, so that utilities such as water are affected by the heat released from the second heating means. This can be suppressed.

The first heating step, the second heating step, the heat exchange step, and the acid component removal step are performed at a position along one side of the rectangular region inside the rectangular region when viewed from above, The gas containing perfluoride flowing into the heat exchange step and the exhaust gas after flowing out from the acid component removal step are introduced and discharged from one short side of the rectangular region, respectively, and the second heating step is performed in the rectangular region. By performing at the position on the other short side, the treatment of perfluoride can be performed within a smaller area.

It is the figure explaining the whole structure of the semiconductor manufacturing factory to which the processing apparatus of the perfluoride of this Embodiment is applied. It is the figure explaining schematic structure of the processing device of perfluoride of this embodiment. It is the figure which showed each apparatus which comprises the processing apparatus of the perfluoride of this Embodiment. It is a figure explaining the relationship between reaction temperature and the decomposition rate of perfluoride. It is the flowchart explaining operation | movement of the processing apparatus of perfluoride. It is the figure which looked at the processing apparatus of the perfluoride actually manufactured from the upper direction. It is the figure which looked at the processing apparatus of the perfluoride actually manufactured from the VII direction of FIG.

Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention. The drawings used are for explaining the present embodiment and do not represent the actual size.

<Description of overall configuration of semiconductor manufacturing factory>
FIG. 1 is a diagram illustrating the overall configuration of a semiconductor manufacturing factory to which the perfluoride treatment apparatus of the present embodiment is applied.
As shown in the figure, the semiconductor manufacturing plant of the present embodiment includes a semiconductor manufacturing facility 1 that manufactures semiconductors, a perfluoride processing device 2 that decomposes perfluoride, and an acid scrubber that collects acid gas. 3.
The semiconductor manufacturing facility 1 is normally a clean room. In the example shown in the figure, a P-Si etcher 11 for etching silicon / polysilicon as a semiconductor and an oxide film such as silicon oxide (SiO ₂ ) as an insulating film are used. An oxide film etcher 12 for etching a metal film and a metal etcher 13 for etching a metal film for use in wiring.
The P-Si etcher 11, the oxide film etcher 12, and the metal etcher 13 are dry etching (dry etching) apparatuses, for example, reactive ion etching (RIE: Etching) using a reactive etching gas in a process chamber. Reactive Ion Etching) device.

The etching gas used in the P-Si etcher 11, the oxide film etcher 12, and the metal etcher 13 is different, but various perfluorides (due to this etching gas) are used as the gas exhausted after dry etching in each apparatus. hereinafter also referred to as a PFC (perfluorocompound)) and CHF ₃ and the like. Examples of the perfluoride include CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , and SF ₆ . The exhausted gas containing perfluoride, that is, the etching exhaust gas is discharged out of the semiconductor manufacturing facility 1 by the collection duct 15 after the toxic gas such as chlorine (Cl ₂ ) gas is removed by the toxic gas abatement apparatus 14. Is done. In the present embodiment, the etching exhaust gas discharged out of the semiconductor manufacturing facility 1 is, for example, a gas containing 99% N ₂ (nitrogen) gas as a carrier gas and 1% perfluoride. In the present embodiment, the perfluoride contained in the etching exhaust gas is preferably 1% or less. Further, the flow rate of the etching exhaust gas discharged is, for example, 3000 L / min to 3500 L / min.

As will be described in detail later, the perfluoride treatment apparatus 2 detoxifies perfluoride by decomposing perfluoride contained in the etching exhaust gas discharged from the semiconductor manufacturing facility 1 and then discharges it as exhaust gas. To do. For this purpose, the etching exhaust gas discharged from each facility of the semiconductor manufacturing facility 1 and collected via the duct is introduced into the perfluoride treatment device 2 via the three-way valve 4. The perfluoride treatment apparatus 2 does not need to be installed in a clean room, and is usually installed outside the semiconductor manufacturing facility 1.

The acid scrubber 3 collects acid gas. The detoxified gas after collecting the acid gas is discharged outside the semiconductor manufacturing factory. The acid scrubber 3 plays a role of collecting perfluoride even when the perfluoride treatment apparatus 2 cannot completely remove the perfluoride. Further, even when a failure or the like occurs in the perfluoride treatment apparatus 2, it plays a role as a backup of the perfluoride treatment apparatus 2. In other words, in a normal state, the gas containing perfluoride is introduced into the perfluoride processing device 2 by the three-way valve 4, and the perfluoride is decomposed and processed by the perfluoride processing device 2. However, when a failure or the like occurs in the perfluoride treatment apparatus 2, the three-way valve 4 is switched so that a gas containing perfluoride is directly introduced into the acid scrubber 3.
Although not shown in FIG. 1, an alkali scrubber for collecting acid gas contained in the etching exhaust gas discharged from the semiconductor manufacturing facility 1 may be provided on the upstream side of the three-way valve 4.

<Description of configuration of perfluoride treatment apparatus>
Hereinafter, the perfluoride treatment apparatus 2 will be described in more detail.
FIG. 2 is a diagram illustrating a schematic configuration of the perfluoride treatment apparatus 2 of the present embodiment.
As shown in the figure, the perfluoride treatment apparatus 2 includes a pretreatment unit 21 that pretreats the introduced apparatus inlet exhaust gas (etching exhaust gas), and a perfluoride contained in the apparatus inlet exhaust gas pretreated by the pretreatment unit 21. Perfluoride decomposition unit 22 for decomposing fluoride, and HF adsorption for dry removal by adsorbing decomposition gas containing HF (hydrogen fluoride) generated when perfluoride is decomposed by perfluoride decomposition unit 22 A unit 23. Then, the exhaust gas at the inlet of the apparatus is treated by each of these units to make it harmless, and then exhausted out of the perfluoride processing apparatus 2 as exhaust gas.

FIG. 3 is a diagram showing each device constituting the perfluoride treatment apparatus 2 of the present embodiment.
As described with reference to FIG. 2, the perfluoride treatment apparatus 2 mainly includes a pretreatment unit 21, a perfluoride decomposition unit 22, and an HF adsorption unit 23. Further, as shown in the figure, the perfluoride treatment apparatus 2 includes a control unit 24, and controls each device and valves (not shown) provided in the perfluoride treatment apparatus 2.

The pretreatment unit 21 includes an inlet heater 211 for preheating the exhaust gas at the apparatus inlet and a filter 212 for removing fine particles.
The inlet heater 211 evaporates minute water droplets (mist) contained in the apparatus inlet exhaust gas by preheating the apparatus inlet exhaust gas. The inlet heater 211 includes a heater 211a around a pipe through which the apparatus inlet exhaust gas passes. The apparatus inlet exhaust gas is heated by the heater 211a when passing through the inlet heater 211, and is preheated to a temperature at which mist evaporates. At this time, the temperature of the exhaust gas at the inlet of the apparatus preheated can be set to 60 ° C., for example. Thereby, in the next filter 212, it can suppress that a filter is obstruct | occluded with mist.

The filter 212 removes fine particles as a solid content contained in the exhaust gas at the inlet of the apparatus. In the semiconductor manufacturing facility 1, fine particles such as silicon oxide shaved when performing the above-described dry etching are generated. Since the fine particles are mixed in the exhaust gas at the inlet of the apparatus, the filter 212 removes the fine particles. The filter 212 is not particularly limited as long as it allows the exhaust gas at the inlet of the apparatus to pass therethrough and collects fine particles. For example, a mesh filter or the like can be used.
The pretreatment unit 21 can be grasped as a pretreatment means for removing solid content and / or mist from the exhaust gas at the inlet of the apparatus.

In this embodiment, air is introduced between the inlet heater 211 and the filter 212. Oxygen may be required to suppress the formation of carbon monoxide in the next perfluoride decomposition unit 22, so air is mixed with the apparatus inlet exhaust at this stage.
In this embodiment, as will be described in detail later, the exhaust gas at the inlet of the apparatus after passing through the filter 212 once enters the heat exchanger 231. The apparatus inlet exhaust gas is heated by heat exchange in the heat exchanger 231. Further, at this time, water necessary for the reaction for decomposing the perfluoride is added in a liquid state in the next perfluoride decomposition unit 22. This water is heated together with the exhaust gas at the inlet of the apparatus in the heat exchanger 231 and becomes gaseous water vapor. And it is transferred while mixing with the exhaust gas at the inlet of the apparatus. In the present embodiment, pure water is used as the water, and the amount added is an amount commensurate with the reaction formula described later, for example, 350 mL / min. Further, this water may be heated in advance and added to the heat exchanger 231 as water vapor.

The perfluoride decomposition unit 22 further heats the apparatus inlet exhaust gas and water heated by the first heater 221 as an example of first heating means for heating the apparatus inlet exhaust gas and water. In addition, a second heater 222 which is an example of second heating means for hydrolyzing perfluoride with a predetermined catalyst to generate a cracked gas containing an acidic gas is provided.

The first heater 221 is provided with a heater 221a. The heater 221a heats the exhaust gas at the inlet of the apparatus and the water added to the heat exchanger 231 to become water vapor. The exhaust gas at the inlet of the apparatus after passing through the first heater 221 is, for example, 450 ° C. to 500 ° C. In the present embodiment, the first heater 221 is a horizontal heater in which the flow path of the apparatus inlet exhaust gas is in the horizontal direction.

The second heater 222 introduces apparatus inlet exhaust gas from above, and further heats the apparatus inlet exhaust gas and water vapor by a heater 222a provided therein. As a result, the exhaust gas at the inlet of the apparatus is heated to 750 ° C., for example.
Further, the heated exhaust gas at the inlet of the apparatus reacts with the water (steam) mixed with the exhaust gas at the inlet of the apparatus in the catalyst layer 222b disposed below the second heater 222 and is decomposed.
As the decomposition reaction at this time, the case of CF ₄ , CHF ₃ , C ₂ F ₆ and SF ₆ as the perfluoride is taken as an example, and the reaction formula is shown below.

CF ₄ + 2H ₂ O → CO ₂ + 4HF (1)
CHF ₃ + (1/2) O ₂ + H ₂ O → CO ₂ + 3HF (2)
C ₂ F ₆ + 3H ₂ O + (1/2) O ₂ → 2CO ₂ + 6HF (3)
SF ₆ + 3H ₂ O → SO ₃ + 6HF (4)

As can be seen from the above formulas (1) to (4), perfluoride becomes a decomposition gas containing HF (hydrogen fluoride) which is an acid component by a hydrolysis reaction. In this case, HF can also be regarded as an acidic gas contained in the cracked gas.

FIG. 4 is a diagram illustrating the relationship between the reaction temperature and the decomposition rate of perfluoride.
Here, CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , SF ₆ , and NF ₃ are exemplified as the perfluoride contained in the etching exhaust gas. Further, although not a perfluoride, CO is also shown as a component contained in the gas discharged from the semiconductor manufacturing facility 1.
As shown in the figure, since each component has a decomposition rate of almost 100% near 750 ° C., the reaction at a temperature of 750 ° C. can almost remove perfluoride and the like.

As the catalyst constituting the catalyst layer 222b, in this embodiment, Al ₂ O ₃ (aluminum oxide), Zn (zinc), Ni (nickel), Ti (titanium), F (fluorine), Sn (tin) , Co (cobalt), Zr (zirconium), Ce (cerium), Si (silicon) and other oxides can be used. More specifically, for example, a composition comprising 80% by weight of Al ₂ O ₃ (aluminum oxide) and 20% by weight of NiO (nickel oxide) can be used.

The cracked gas containing HF after the perfluoride is decomposed by the second heater 222 is discharged from below the second heater 222 and sent to the next HF adsorption unit 23. At this time, the temperature of the cracked gas discharged from the second heater 222 is about 600 ° C. to 700 ° C.

The HF adsorption unit 23 mixes water with a gas containing perfluoride before flowing into the first heater 221, which is arranged at the front stage of the first heater 221 and the rear stage of the second heater 222, and the second heater Heat exchanger 231 which is an example of heat exchange means for exchanging heat with cracked gas after flowing out from 222, and reacting an acid component with calcium salt from the cracked gas after flowing out from heat exchanger 231 An acid component removing device 232 as an example of an acid component removing means for dry-removing by an acid, and an ejector 233 as an example of an exhaust gas discharging means for discharging exhaust gas after the acid component is removed by the acid component removing device 232 Is provided.

The HF adsorption unit 23 includes a medicine supply device 234 that is an example of a medicine supply unit that supplies calcium salt, which is a medicine for dry removal of HF from above the acid component removal apparatus 232, and a lower part of the acid component removal apparatus 232. A medicine discharge device 235 which is an example of a medicine discharge means for discharging used calcium salt from the HF, a HF concentration sensor 236 for monitoring the concentration of HF contained in the gas discharged from the acid component removal device 232, and an HF concentration A powder trap 237 that is disposed between the sensor 236 and the ejector 233 and removes the solid content generated by the acid component removing device 232 is further provided.

The heat exchanger 231 performs heat exchange between the high-temperature cracked gas discharged from the second heater 222 and the aforementioned low-temperature apparatus inlet exhaust gas before being introduced into the first heater 221. As a result, the temperature of the cracked gas decreases, and the temperature of the exhaust gas at the apparatus inlet before being introduced into the first heater 221 increases. Further, as described above, the water added to the heat exchanger 231 evaporates to become water vapor.
The cracked gas after passing through the heat exchanger 231 decreases in temperature to about 300 ° C. to 500 ° C., and the exhaust gas at the inlet of the apparatus after passing through the heat exchanger 231 increases in temperature to about 200 ° C. to 300 ° C. .

The heat exchanger 231 is not particularly limited, and two plate plates are alternately arranged, a flow path is formed between the plates, and a plate-type heat that exchanges heat between the apparatus inlet exhaust gas and the cracked gas. It is possible to use an exchanger, or a shell-and-tube type heat exchanger that exchanges heat between the shell exhaust gas and cracked gas through the shell (cylinder) and a number of tubes (heat transfer tubes). Moreover, it may be a double-pipe heat exchanger having a double-pipe structure in which a high-temperature cracked gas flows through the inner pipe and a low-temperature apparatus inlet exhaust gas flows through the outer pipe. Further, the apparatus inlet exhaust gas and the cracked gas may flow oppositely or may flow in parallel. In the present embodiment, a double-tube heat exchanger is used, and the apparatus inlet exhaust gas and the cracked gas are caused to flow opposite to each other.

The acid component removing device 232 is filled with a drug layer 232a made of a calcium salt, and HF contained in the decomposition gas is dry-removed by an adsorption reaction with the calcium salt. As the calcium salt, CaCO ₃ (calcium carbonate), Ca (OH) ₂ (calcium hydroxide), CaO (calcium oxide), or the like can be used. The shape of the calcium salt may be powder, but is preferably a pellet molded into a cylindrical shape or a spherical shape for ease of handling. In the present embodiment, for example, a mixture of Ca (OH) ₂ and CaCO ₃ and using CaCO ₃ : Ca (OH) ₂ = 50 wt% to 80 wt%: 20 wt% to 50 wt% is used. To do. In this case, the moldability is good and pulverization can be suppressed when the pellet is formed. In the present embodiment, this mixture is used as a cylindrical pellet having a bottom diameter of about 3 mm and a height of about 8 mm.

As an adsorption reaction at this time, the case where CaCO ₃ or Ca (OH) ₂ is used as a calcium salt is taken as an example, and the reaction formula is shown below.

CaCO ₃ + 2HF → CaF ₂ + CO ₂ + H ₂ O (5)
Ca (OH) ₂ + 2HF → CaF ₂ + 2H ₂ O (6)

As can be seen from the above formulas (5) to (6), HF reacts with calcium salt, and CaF ₂ (calcium fluoride (fluorite)), CO ₂ (carbon dioxide), and H ₂ O (water) Arise.

The ejector 233 is connected to a compressed air pipe through which compressed air flows. The exhaust gas is sucked by the negative pressure generated by flowing the compressed air at a high speed, and discharged together with the compressed air to the outside of the perfluoride processing apparatus 2. To do. As a result, the exhaust gas is further discharged at a reduced temperature. The exhaust gas after being discharged from the acid component removing device 232 is, for example, about 200 ° C., but the exhaust gas discharged from the ejector 233 is, for example, 100 ° C. or less.

The cracked gas is introduced from below the acid component removing device 232 and discharged from above the acid component removing device 232. While the cracked gas flows from the lower side to the upper side of the acid component removing device 232, the reaction between HF and the calcium salt exemplified in the above formula (3) occurs, and HF is dry-removed. At this time, the calcium salt becomes CaF ₂ , and no further reaction occurs, so it is necessary to sequentially exchange the calcium salt.

Therefore, in the present embodiment, a medicine supply device 234 that supplies calcium salt to the acid component removal device 232 and a medicine discharge device 235 that discharges the used calcium salt from the acid component removal device 232 are provided.

In the present embodiment, the HF concentration sensor 236 monitors the HF concentration, and when the HF concentration reaches, for example, 100 ppm, it is determined that it is time to replace the calcium salt. And the rotary valve (not shown) etc. which were provided in the chemical | medical agent discharge apparatus 235 are opened and closed, and predetermined amount used calcium salt is discharged | emitted. In addition, after discharging the used calcium salt, a rotary valve (not shown) provided in the medicine supply device 234 is opened and closed to supply new calcium salt for the discharged amount. In this way, the calcium salts in the medicine discharge device 235 are sequentially replaced. In this series of procedures, the control unit 24 acquires information on the concentration of HF sent from the HF concentration sensor 236, and when the concentration of HF reaches, for example, 100 ppm, the medicine supply device 234 and the medicine discharge This is automatically performed by controlling opening and closing of a rotary valve provided in the device 235. At this time, all of the calcium salt may be exchanged, but usually only a part is exchanged. The exchange amount of the calcium salt is, for example, 40 kg / h.

The powder trap 237 is provided to remove calcium salt powder or the like generated in the acid component removing device 232 when the calcium salt is exchanged. As the powder trap 237, a metal mesh filter or the like can be used.
In the present embodiment, the powder trap 237 can be grasped as a post-processing means for removing the solid content from the exhaust gas after the acid component is removed by the acid component removing device 232.

<Description of operation of perfluoride treatment apparatus>
FIG. 5 is a flowchart for explaining the operation of the perfluoride treatment apparatus 2.
Hereinafter, the operation of the perfluoride treatment apparatus 2 will be described with reference to FIGS. 3 and 5.
First, the apparatus inlet exhaust gas passes through the inlet heater 211 of the pretreatment unit 21 and is preheated (step 101). As a result, the mist contained in the exhaust gas at the inlet of the apparatus evaporates.
Next, air is introduced into the preheated apparatus inlet exhaust gas, and fine particles are removed by the filter 212 of the pretreatment unit 21 (step 102).

The exhaust gas at the inlet of the apparatus is heated by heat exchange by the heat exchanger 231 (step 103). At this time, water necessary for the decomposition reaction of perfluoride is added (step 104).
The apparatus inlet exhaust gas that has passed through the heat exchanger 231 is first heated by the first heater 221 (step 105), and further heated by the second heater 222 to a temperature necessary for decomposition of perfluoride (step 105). 106). Then, the perfluoride is decomposed when passing through the catalyst layer 222b of the second heater 222, and the exhaust gas at the inlet of the apparatus becomes a decomposition gas containing HF (step 107).

The cracked gas enters the heat exchanger 231 again, and performs heat exchange with the above-described apparatus inlet exhaust gas (step 108).

Then, the cracked gas reacts with the calcium salt in the acid component removing device 232, and HF is dry-removed (step 109). At this time, the control unit 24 determines whether or not the HF concentration acquired by the HF concentration sensor 236 has become a predetermined value or more (step 110). And when it becomes more than a predetermined value (it is Yes at Step 110), medicine discharge device 235 and medicine supply device 234 are operated, and calcium salt is exchanged (Step 111). If it is less than the predetermined value (No in step 110), the calcium salt is not exchanged and the process proceeds to the next step 112.

The exhaust gas from which HF has been dry removed is removed from the perfluoride processing apparatus 2 by the ejector 233 after the powder is removed by the powder trap 237 (step 112) (step 113).

The perfluoride treatment apparatus 2 described in detail above has the following features.
(I) Since the perfluoride is decomposed using the catalyst layer 222b, a large amount of etching exhaust gas can be treated and the operating cost can be reduced.
(ii) HF contained in the cracked gas is dry-removed by an adsorption reaction with a calcium salt, so that wastewater containing HF is not generated as compared with a conventional method of removing HF by dissolving HF in water. Moreover, CaF ₂ produced after the adsorption reaction is harmless and easy to handle. Further, CaF ₂ is a valuable material because it becomes a raw material for producing HF. That is, CaF ₂ which is a valuable material can be produced from etching exhaust gas harmful to the global environment.
(Iii) By using the heat exchanger 231 to exchange heat between the exhaust gas at the inlet of the apparatus and the cracked gas, the energy utilization efficiency increases. Moreover, compared with the conventional method of cooling the cracked gas with water, drainage does not occur. This eliminates the need for a wastewater treatment process and reduces the operating cost of the perfluoride treatment apparatus 2.
(iv) By incorporating the drug supply device 234 disposed above the acid component removal device 232 and the drug layer 232a having the drug discharge device 235 below, it is possible to simply drop it using gravity simply by opening the valve. The system allows the exchange of calcium salts. In this embodiment, the decomposition gas is introduced from below and exhausted from above, and the HF concentration sensor 236 is provided, and the HF concentration is monitored to determine the replacement timing of the calcium salt. As a result, the upper layer portion of the drug layer 232a is not discharged, and only the reacted calcium salt of the lower layer portion is discharged, so that almost no unreacted calcium salt is generated, and wasteful consumption of the calcium salt can be reduced. it can.

<Description of actual perfluoride treatment apparatus>
FIG. 6 is a view of the actually produced perfluoride treatment apparatus 2 as viewed from above. FIG. 7 is a view of the actually produced perfluoride treatment apparatus 2 as seen from the direction VII in FIG. That is, FIG. 7 is a view of the perfluoride treatment apparatus 2 as seen from the horizontal direction.
As shown in the figure, the actual perfluoride treatment apparatus 2 has almost all the devices arranged inside the rectangular area when viewed from above or when viewed from the horizontal direction. The control unit 24 is disposed outside the rectangular area. Note that the rectangle in this embodiment is a basic shape, but a trapezoid, a parallelogram, an ellipse, or the like close to the rectangle can be included in the rectangle without departing from the characteristics of this embodiment.

Next, each device of the perfluoride treatment apparatus 2 in FIGS. 6 and 7 will be described. In the following description, it is assumed that the position where the control unit 24 is installed is the lower left side of the perfluoride treatment apparatus 2 when viewed from above.

The exhaust gas at the inlet of the apparatus is introduced from the lower left side of the perfluoride processing apparatus 2. Then, it flows in the right direction in the figure through a plurality of pipes, and passes through an inlet heater 211 installed on the lower side of the perfluoride treatment apparatus 2. At this time, preheating is performed by a heater 211a (see FIG. 3) arranged in the inlet heater 211. As a result, the mist contained in the exhaust gas at the inlet of the apparatus is evaporated. Further, the apparatus inlet exhaust gas that has passed through the inlet heater 211 is further caused to flow in the right direction in the drawing and introduced into the filter 212 to remove particulates contained in the apparatus inlet exhaust gas. Although not shown, air is introduced into the apparatus inlet exhaust gas after passing through the inlet heater 211.

In this embodiment, not only the filter 212 but also a spare filter 212a is provided as a filter. That is, when the filter 212 needs to be replaced due to blockage or the like, by operating a valve or the like provided in the pipe connected to the filter 212, the pipe through which the exhaust gas from the apparatus is circulated can be switched. The apparatus inlet exhaust gas flows into the filter 212a. Thus, the particulate matter can be removed by the preliminary filter 212a during the replacement operation of the filter 212, and the replacement operation of the filter 212 can be performed without stopping the operation of the perfluoride treatment apparatus 2.

The exhaust gas at the inlet of the apparatus after passing through the filter 212 flows in the direction of arrow A through the pipe P1 and enters the heat exchanger 231 installed on the upper side of the perfluoride treatment apparatus 2. The exhaust gas at the inlet of the apparatus is heated by heat exchange by the heat exchanger 231. Although not shown, water is added to the heat exchanger 231 at this time, and this water is converted into water vapor and carried along with the exhaust gas at the inlet of the apparatus.

The apparatus inlet exhaust gas discharged from the heat exchanger 231 flows in the direction of arrow B through the pipe P2 and enters the first heater 221 installed on the lower right side of the perfluoride treatment apparatus 2. The first heater 221 is a horizontal heater, and the apparatus inlet exhaust gas flows from the left side in the figure, and the apparatus inlet exhaust gas is discharged from the right side in the figure. The first heater 221 is provided with a heater 221a (see FIG. 3), and is heated when the apparatus inlet exhaust gas moves from the left side to the right side inside the first heater 221.

Next, the apparatus inlet exhaust gas discharged from the first heater 221 flows in the direction of arrow C through the pipe P3 and enters the second heater 222 installed on the upper right side of the perfluoride treatment apparatus 2. The second heater 222 is a vertical heater, in which a heater 222a (see FIG. 3) is disposed above, and a catalyst layer 222b (see FIG. 3) is disposed below. The exhaust gas at the inlet of the apparatus flows from above the second heater 222 and flows below the second heater 222 while being heated to the decomposition temperature of perfluoride by the heater 222a. In the catalyst layer 222b, the perfluoride reacts with water (steam) mixed with the exhaust gas at the inlet of the apparatus and is decomposed. And it becomes acidic decomposition gas containing HF which is a product after decomposition, and is discharged from the lower part of the 2nd heater 222.

The cracked gas discharged from the second heater 222 flows in the direction of arrow D through the pipe P4 and enters the heat exchanger 231 again. In the heat exchanger 231, heat exchange is performed between the high-temperature cracked gas and the low-temperature apparatus inlet exhaust gas.

The cracked gas discharged from the heat exchanger 231 flows in the direction of arrow E (left direction in the figure) through the pipe P5 and enters the acid component removing device 232 installed on the upper side of the perfluoride treatment device 2. At this time, the cracked gas flows from below the acid component removing device 232 and flows above the acid component removing device 232. At this time, in the drug layer 232a made of calcium salt (see FIG. 3), HF contained in the decomposition gas undergoes an adsorption reaction and is dry-removed. The exhaust gas is rendered harmless and is discharged from above the acid component removing device 232.

The exhaust gas discharged from the acid component removing device 232 flows in the direction of arrow F (left direction in the figure) through the pipe P6 and enters the powder trap 237 installed on the upper left side of the perfluoride treatment device 2. Then, powder of calcium salt or the like is removed by the powder trap 237. An HF concentration sensor 236 is disposed in the middle of the pipe P6, and measures the concentration of HF contained in the exhaust gas. Further, in the present embodiment, the pipe P6 is relatively long and includes heat dissipating fins around it. In other words, the pipe P6 connected to the acid component removing device 232 and directed to the ejector 233 is disposed along the other long side of the rectangular region and includes a heat radiation fin for cooling the exhaust gas. Thereby, the temperature of the exhaust gas can be further reduced.

The exhaust gas discharged from the powder trap 237 is finally sucked by the ejector 233 installed on the upper left side of the perfluoride treatment apparatus 2 and flows in the direction of arrow G (upward in the figure) through the pipe P7. It is discharged outside.

In the layout of each device described in detail above, each device including the first heater 221, the second heater 222, the heat exchanger 231, and the acid component removing device 232 is inside the rectangular area when viewed from above. Are arranged along any side of the rectangular area.

And the exhaust gas after flowing out from the apparatus inlet exhaust gas and the acid component removing device 232 flowing into the heat exchanger 231 is introduced and discharged from one short side of the rectangular region, respectively, and the second heater 222 is disposed in the rectangular region. It is arranged on the other short side.
That is, in the example shown in FIG. 6, the apparatus inlet exhaust gas and exhaust gas are respectively introduced and discharged from the short side on the left side of the rectangular region, and the second heater 222 is short on the right side of the rectangular region on the opposite side. Arranged on the side.

Thus, safety can be improved by arranging the high-temperature second heater 222 at a position deeper along the short side of the rectangular region. Further, when exchanging the catalyst in the second heater 222, it is easy to access from the outside of the rectangular region of the perfluoride treatment apparatus 2, and the convenience of exchanging work can be improved.
The exhaust gas and exhaust gas at the inlet of the apparatus are introduced and discharged from the short side opposite to the second heater 222, respectively, so that the heat exchanger 231 and the acid component removing device 232 are disposed between the short sides of the rectangular region. Such other devices can be arranged in order, and the perfluoride treatment apparatus 2 can be easily downsized.

In the present embodiment as an arrangement of other devices, the first heater 221 is arranged along with the second heater 222 on the other short side of the rectangular region, and the heat exchanger 231 and the acid component removing device 232 are Then, they are arranged in order along the long side of the rectangular area toward the location where the exhaust gas flows out.
That is, in the example shown in FIG. 6, the first heater 221 is arranged side by side with the second heater 222 along the short side on the right side of the rectangular area. The heat exchanger 231 and the acid component removing device 232 are arranged in order from the right side toward the left side toward the location where the exhaust gas flows out along the long side above the rectangular region.

In addition, the inlet heater 211 and the filter 212 are on the long side different from the long side where the heat exchanger 231 and the acid component removing device 232 are arranged, and the location where the exhaust gas from the device inlet flows into the first heater 221. The powder trap 237 and the ejector 233 are arranged on the long side where the heat exchanger 231 and the acid component removing device 232 are arranged, and are arranged between the acid component removing device 232 and the location where the exhaust gas flows out. Is done.
That is, in the example shown in FIG. 6, the inlet heater 211 and the filter 212 are on the lower long side that is different from the long sides on which the heat exchanger 231 and the acid component removing device 232 are arranged, and the apparatus inlet exhaust gas flows in. It arrange | positions between the location to perform and the 1st heater 221. Further, the powder trap 237 and the ejector 233 are arranged between the long side on the upper side where the heat exchanger 231 and the acid component removing device 232 are arranged, and between the acid component removing device 232 and the location where the exhaust gas flows out. .

In the example shown in FIG. 6, the heat exchanger 231 is arranged between the second heater 222 and the acid component removing device 232 on the long side on the upper side of the rectangular region. However, the present invention is not limited to this, and the heater may be arranged along the lower long side where the inlet heater 211, the filter 212, and the first heater 221 are arranged.

Thus, the safety can be further improved by arranging the high-temperature first heater 221 along with the second heater 222 along the other short side of the rectangular region.
In addition, by arranging the devices in this way, the devices are arranged in a substantially U shape as indicated by the arrow H direction in the order in which the gas flows. Therefore, for example, as compared with the case where the devices are arranged in a straight line, the length occupied by the perfluoride treatment apparatus 2 when viewed from above is reduced and the area is also reduced. Therefore, the entire apparatus can be made compact and can be sized to fit in a container or the like. The perfluoride treatment apparatus 2 of the present embodiment can be sized to be suitable for transportation that can fit in a 20-foot container.

In addition, by arranging the devices in this manner, it is possible to form a passage in the central portion sandwiched between the two long sides. In FIG. 6, a location where the worker can move through this passage is indicated by a double arrow T. The pipes P1, P2, and P3 are arranged above, and the worker can move along the passage without causing the pipes P1, P2, and P3 to be obstructed. In this way, when operating or maintaining each device, access is possible not only from the outside of the rectangular area but also from the inside by using the passage, and convenience is improved.

Further, in the layout of each device described in detail above, the water mixed in the heat exchanger 231 and necessary for decomposing the apparatus inlet exhaust gas is supplied from one short side of the rectangular region. Also, the device driving air (compressed air) is also supplied from one short side of the rectangular region.
That is, in the example shown in FIG. 6, water and compressed air are supplied from the short side on the left side of the rectangular area.
In this way, the introduction of exhaust gas at the inlet of the apparatus, the discharge of exhaust gas, the supply of water, and the utility such as compressed air used in the ejector 233 are concentrated on one short side of the rectangular region, thereby The processing device 2 can be further reduced in size. And since the high temperature 1st heater 221 and the 2nd heater 222 are arrange | positioned at the other short side of a rectangular area, the utility and its instrument and adjustment work space are the 1st heater 221 and the 2nd heater. The influence of heat released from 222 can be suppressed.

The perfluoride treatment method performed by the perfluoride treatment apparatus 2 described above includes a first heating process for heating the apparatus inlet exhaust gas and water, and an apparatus inlet exhaust gas and water heated by the first heating process. A second heating step of further heating and hydrolyzing the perfluoride with a predetermined catalyst to generate a cracked gas containing an acidic gas; a first stage of the first heating step and a subsequent stage of the second heating step; From the heat exchange step, which mixes water with the exhaust gas at the inlet of the apparatus before flowing into the first heating step and exchanges heat with the cracked gas after flowing out from the second heating step, An acid component removal step for dry-removing the acid component from the cracked gas after flowing out, the first heating step, the second heating step, the heat exchange step and the acid component removal step when viewed from above Inside the rectangular area The exhaust gas exhausted from the apparatus inlet exhaust gas and the acid component removal process that flows into the heat exchange process at positions along either side of the rectangular area is introduced from one short side of the rectangular area, respectively. The second heating step can be regarded as a method for treating perfluoride, characterized in that the second heating step is performed at a position on the other short side of the rectangular region.

In the above-described example, the case where the perfluoride contained in the etching exhaust gas discharged at the semiconductor manufacturing factory is treated has been described. However, the present invention is not limited to this. For example, it may be a case where perfluoride contained in etching exhaust gas or cleaning exhaust gas discharged from a liquid crystal manufacturing factory or the like is processed.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor manufacturing equipment, 2 ... Perfluoride processing apparatus, 3 ... Acid scrubber, 21 ... Pretreatment unit, 22 ... Perfluoride decomposition unit, 23 ... HF adsorption unit, 24 ... Control unit, 211 ... Inlet heater , 212 ... Filter, 221 ... First heater, 222 ... Second heater, 231 ... Heat exchanger, 232 ... Acid component removal device, 233 ... Ejector

Claims

A first heating means for heating a gas containing perfluoride and water;
A gas containing water and perfluoride heated by the first heating means is further heated, and a hydrofluoric acid is hydrolyzed by a predetermined catalyst to generate a cracked gas containing an acid gas. Heating means;
Water is mixed with the gas containing the perfluoride before flowing into the first heating means, which is arranged before the first heating means and after the second heating means, and the second heating means. Heat exchange means for exchanging heat with the cracked gas after flowing out of
Acid component removing means for dry-removing the acid component from the cracked gas that has flowed out of the heat exchange means;
With
The first heating means, the second heating means, the heat exchanging means, and the acid component removing means are inside the rectangular area when viewed from above and along any side of the rectangular area. Arranged,
The gas containing perfluoride flowing into the first heating means and the exhaust gas after flowing out from the acid component removing means are introduced and discharged from one short side of the rectangular region, respectively, and the second heating The means is disposed on the other short side of the rectangular region.
The first heating means is arranged side by side with the second heating means on the other short side of the rectangular region,
2. The perfluoride according to claim 1, wherein the heat exchanging means and the acid component removing means are arranged in order toward a location where the exhaust gas flows out along a long side of the rectangular region. Processing equipment.
Pretreatment means for removing solids and / or mist from a gas containing perfluoride;
Post-treatment means for removing solids from the exhaust gas after the acid component has been dry-removed by the acid component removal means;
Further comprising
The pretreatment means has a long side that is different from the long side where the heat exchange means and the acid component removal means are arranged, and a portion into which a gas containing perfluoride flows and the first heating means Between
The post-treatment means is arranged on the long side where the heat exchange means and the acid component removal means are arranged, and is arranged between the acid component removal means and a location where the exhaust gas flows out. The apparatus for treating perfluoride according to claim 2.
A medicine supply means for supplying a medicine for dry removal of the acid component from above the acid component removal means, and a medicine discharge means for discharging the medicine from below the acid component removal means,
The cracked gas introduced into the acid component removing means is introduced from below the acid component removing means and discharged from above the acid component removing means. The perfluoride processing apparatus as described.
5. The water and / or device driving air mixed in the heat exchanging means is supplied from one short side of the rectangular region. Perfluoride processing equipment.
A first heating step for heating a gas containing perfluoride and water;
The gas and water containing the perfluoride heated by the first heating step are further heated, and the perfluoride is hydrolyzed by a predetermined catalyst to generate a cracked gas containing an acid gas. Heating process;
In the first stage of the first heating step and the second stage of the second heating step, water is mixed with the gas containing perfluoride before flowing into the first heating step and the water flows out of the second heating step. A heat exchange process for exchanging heat with the cracked gas after
An acid component removal step of dry-removing the acid component from the cracked gas after flowing out of the heat exchange step;
With
The first heating step, the second heating step, the heat exchange step, and the acid component removal step are inside a rectangular region when viewed from above and along any side of the rectangular region. Done at
The gas containing perfluoride flowing into the heat exchange step and the exhaust gas after flowing out from the acid component removal step are introduced and discharged from one short side of the rectangular region, respectively, and the second heating step A method for treating perfluoride, which is performed at a position on the other short side of the rectangular region.