JP5284873B2 - Gas processing apparatus and semiconductor manufacturing apparatus - Google Patents

Description

  The present invention relates to an apparatus for treating a gas containing a fluorine-containing compound. In particular, the present invention relates to a gas processing apparatus for recovering fluorine by decomposing and processing a perfluoro compound (PFC) contained in a gas, and a semiconductor manufacturing apparatus including the apparatus.

The exhaust gas discharged in the semiconductor manufacturing process contains perfluoro compounds (PFC) including CF ₄ . This perfluoro compound is socially required to be suppressed and reduced as a greenhouse gas.

Conventionally, various methods have been adopted for treating perfluoro compounds contained in exhaust gas. For example, there is a method in which a gas containing CF ₄ or sulfur fluoride or sulfur fluoride is brought into contact with a decomposition treatment agent in which aluminum oxide and an oxide of an alkaline earth metal are mixed (Patent Document 1, Patent Document 2). In addition, the PFC-containing gas is brought into contact with a decomposition treatment agent produced from alumina and an alkaline earth metal carbonate (Patent Document 3). Furthermore, the PFC-containing gas is brought into contact with a decomposition treatment agent containing a mixture of aluminum hydroxide and calcium hydroxide and decomposed (Patent Document 4).

  Such a decomposition treatment agent is required to have a longer decomposition treatment life. As the service life is longer, the number of replacements of the decomposition treatment agent can be reduced at the actual manufacturing site of semiconductors and the like. As a result, the working efficiency is improved and the running cost can be reduced.

JP 2002-224565 A JP 2002-370013 A JP 2001-190959 A JP-A-2005-262128

Therefore, the present invention provides a gas treatment apparatus using a decomposition treatment agent having a longer service life than a mixture of aluminum oxide (Al ₂ O ₃ ) and calcium oxide (CaO), and further, in actual use, It is an object of the present invention to provide a gas processing apparatus including a preprocessing unit and a semiconductor manufacturing apparatus including the apparatus that can extend the service life.

In order to solve the above problems, a gas processing apparatus according to a first aspect of the present invention is a gas processing apparatus 1 for processing a gas containing PFC (perfluoro compound), for example, as shown in FIG. A moisture removing device 10 for reducing H ₂ O contained in a gas containing oxygen, and a gas containing PFC in which H ₂ O is reduced by the moisture removing device 10 are introduced, and Al ₂ O ₃ and CaO that decompose PFC are introduced. The PFC processing apparatus 20 filled with the decomposition treatment agent containing the composite oxide of is provided.

According to this structure, since the composite oxide of Al ₂ O ₃ and CaO as a decomposition treatment agent to the PFC processing apparatus of the gas treatment apparatus is filled, than with the mixture of Al ₂ O ₃ and CaO decomposition The service life of the treatment agent can be extended. Furthermore, when moisture is contained in the gas containing PFC, that is, the PFC-containing gas, the amount of moisture contained in the PFC-containing gas is reduced in the previous stage of the PFC treatment apparatus, and the decomposition treatment agent Al ₂ O ₃ and It can suppress that the processing performance of CaO complex oxide falls by moisture. As a result, the service life of the decomposition treatment agent in actual use can be extended. In the present application, “PFC” means a perfluoro compound, and “perfluoro compound” means perfluorocarbons such as CF ₄ or C ₂ F ₆ , hydrofluorocarbons such as CHF ₃ or CH ₂ F ₂ , hexafluorocarbons. It refers to any compound of sulfur fluoride (SF ₆ ) or nitrogen trifluoride (NF ₃ ).

The gas treatment apparatus according to the second aspect of the present invention is a gas treatment apparatus for treating a gas containing PFC and a gas containing an acid gas and / or a corrosive gas, as shown in FIG. A first dry-type abatement device 160 that removes gas and / or corrosive gas, and Al ₂ O that is disposed downstream of the first dry-type abatement device 160 and decomposes PFC in order to remove PFC ₃ and a PFC treatment apparatus 20 filled with a decomposition treatment agent containing a complex oxide of CaO. That is, the dry-type abatement apparatus 160 is an apparatus that removes at least one of acid gas and corrosive gas.

If comprised in this way, when acidic gas, such as HBr, and corrosive gas are contained in the gas containing PFC, after removing acidic gas etc. beforehand with a 1st dry-type abatement apparatus, it will be in a PFC processing apparatus. A PFC-containing gas can be introduced, the load of the Al ₂ O ₃ and CaO complex oxide in the PFC processing apparatus can be reduced, and the lifetime of the expensive Al ₂ O ₃ and CaO complex oxide can be extended. Furthermore, it is possible to prevent the PFC processing apparatus from being corroded by acid gas or the like.

  For example, as shown in FIG. 6, the gas treatment device according to the third aspect of the present invention includes the heating device in the gas treatment device according to the second aspect of the present invention. The second dry-type abatement device 170 for removing PFC at a temperature higher than 160 is provided. The second dry-type abatement device 170 has a first dry-type abatement device 160 for a gas flow including PFC. It is located downstream and upstream of the PFC processing apparatus 20.

With this configuration, as a pretreatment of the PFC processing apparatus, it is possible to decompose and remove the pre-PFC by second dry scrubber having a heating device, a composite oxide of Al ₂ O ₃ and CaO in the PFC processing apparatus The load can be reduced.

  For example, as shown in FIG. 8, the gas processing apparatus according to the fourth aspect of the present invention is the same as the gas processing apparatus according to the third aspect of the present invention, except that the second dry-type abatement apparatus 170 is a PFC processing apparatus. 20 and a single unit.

If comprised in this way, the gas containing PFC heated with the heating apparatus with which a 2nd dry-type abatement apparatus is equipped can be made to flow in into a PFC processing apparatus as it is. Therefore, the composite oxide of Al ₂ O ₃ and CaO in the PFC processing apparatus can be heated by the gas heated by the second dry-type abatement apparatus in a state where the heat loss of the gas is small.

A gas treatment device according to a fifth aspect of the present invention is the gas treatment device according to any one of the second to fourth aspects of the present invention, wherein the downstream of the first dry-type abatement device 160. The water removal apparatus 10 that reduces H ₂ O contained in the gas containing PFC is provided on the upstream side of the PFC processing apparatus 20.

According to this structure, filled in the PFC processing apparatus, the processing performance of the composite oxide of a decomposition agent Al ₂ O ₃ and CaO it can be inhibited from reduction due to moisture.

The gas treatment device according to the sixth aspect of the present invention is the gas treatment device according to the first or fifth aspect of the present invention, wherein the moisture removing device 10 for reducing H ₂ O is a mist trap, a moisture adsorbent. , And a device having at least one of the heat exchangers.

If comprised in this way, the water | moisture content in which a saturated water vapor | steam content is contained in PFC containing gas at maximum can be reduced by cooling a PFC containing gas with a mist trap or a heat exchanger, and reducing a saturated water vapor | steam amount. . In addition, by using a moisture adsorbent, moisture contained in the PFC-containing gas can be adsorbed and reduced by the moisture adsorbent.
When a mist trap (or heat exchanger) and a moisture adsorbent are used in combination, the moisture amount can be reduced to some extent by the mist trap (or heat exchanger) and then further reduced by the moisture adsorbent. Therefore, by setting the cooling temperature of the mist trap (or heat exchanger) high, the capacity of the heat exchanger for cooling water can be reduced, and the usable time of the moisture adsorbent can be extended.

A gas treatment device according to a seventh aspect of the present invention is the gas treatment device according to any one of the first to sixth aspects of the present invention, wherein the composite oxide of Al ₂ O ₃ and CaO is used. Is a mixture having an average particle diameter (median diameter ) of 55 μm or more and 160 μm or less of Al (OH) ₃ and Ca (OH) ₂ of 3: 7 to 5: 5 at a temperature of 430 ° C. or more and 890 ° C. or less. In the range, it is a complex oxide obtained by calcination in a nitrogen flow or air flow.

According to this structure, it is possible to decompose performance constitutes a gas processing apparatus comprising a composite oxide of a higher Al ₂ O ₃ and CaO.

  For example, as shown in FIG. 2, the semiconductor manufacturing apparatus according to the eighth aspect of the present invention is an etching apparatus 110, 120, 130 for etching a semiconductor substrate, and a semiconductor substrate etched by the etching apparatus 110, 120, 130. The ashing device 140 for removing the unnecessary resist, and the etching device 110, 120, 130 and / or the gas containing the PFC discharged from the ashing device 140 are processed. The gas processing apparatus which concerns on an aspect is provided. In other words, the gas processing apparatus is a gas processing apparatus that processes a gas containing PFC discharged from at least one of the etching apparatuses 110, 120, and 130 and the ashing apparatus 140. The ashing apparatus may be called a resist removal apparatus by the industry.

If comprised in this way, the gas containing PFC discharged | emitted from the etching apparatus or the ashing apparatus can be processed efficiently.
In fact, depending on the semiconductor manufacturing process in the semiconductor manufacturing factory, the exhaust gas may contain a lot of moisture. In such a case, the moisture interferes with the performance of the composite oxide of Al ₂ O ₃ and CaO. It may not be fully utilized. In particular, in an ashing process, there is a possibility that water corresponding to the maximum amount of saturated water vapor flows into the exhaust gas treatment tank. However, even in that case, the semiconductor manufacturing apparatus of the present invention provided with the moisture removing apparatus can efficiently process the gas containing PFC.

According to the present invention, the PFC processing apparatus including a gas treatment apparatus, due to the use of composite oxide of _Al 2 _{O 3} and CaO as a decomposition treatment agent, a decomposition agent consisting of a mixture of _Al 2 _{O 3} and CaO The service life of the decomposition treatment agent can be extended as compared with the case where it is used.
Furthermore, since the moisture content in the PFC-containing gas is reduced in the previous stage of the PFC treatment apparatus and the treatment performance of the composite oxide of Al ₂ O ₃ and CaO is improved, the service life of the decomposition treatment agent in actual use Can provide a longer gas treatment device. Furthermore, the treatment performance of the composite oxide of Al ₂ O ₃ and CaO can be improved by providing the gas treatment device with the dry removal device. Furthermore, a semiconductor manufacturing apparatus including such a gas processing apparatus can be provided. As a result, in the gas processing apparatus and semiconductor manufacturing apparatus of the present invention, the replacement frequency of the complex oxide of Al ₂ O ₃ and CaO can be reduced, the working efficiency can be improved, and the running cost of the apparatus can be reduced.

It is a figure which shows the positional relationship of the water | moisture-content removal apparatus and PFC processing apparatus with which the gas processing apparatus 1 which concerns on embodiment of this invention is provided. It is an example when the gas processing apparatuses 1 and 2 which concern on embodiment of this invention are applied in an actual semiconductor factory. It is another example in case the gas processing apparatuses 1 and 3 which concern on embodiment of this invention are applied in an actual semiconductor factory. (A) and (b) are figures which show the example of the water | moisture-content removal apparatus with which a gas treatment apparatus is provided. It is a longitudinal cross-sectional view of a PFC processing apparatus. It is a figure which shows the structure of the gas processing apparatus 4 which concerns on embodiment of this invention. (A) (b) is the schematic of the apparatus with which the 2nd dry-type abatement apparatus was integrally formed with the 1st dry-type abatement apparatus. (A) (b) is the schematic of the apparatus with which the 2nd dry-type abatement apparatus was integrally formed with the PFC processing apparatus. It is a figure which shows the structure of the gas processing apparatus 5 which concerns on embodiment of this invention. It is the schematic of the baking apparatus used in order to prepare a PFC decomposition processing agent. It is the schematic of the baking apparatus in another aspect used in order to prepare a PFC decomposition processing agent. FIG. 6 is a schematic diagram showing sample collection points in the gas processing apparatus used in Comparative Example 1. 1 is a schematic diagram illustrating a CF ₄ processing system. FIG. It is an XRD analysis data of a PFC decomposition treatment agent. A library peak data of crystalline _Al 2 _{O 3} by XRD analysis. It is XRD analysis data which shows the fluorine fixation of a PFC decomposition processing agent. 3 is XRD analysis data of a control system used in Comparative Example 1. It is the XRD analysis data of the control system used in Comparative Example 1 after CF ₄ gas was passed. It is an XRD analysis data of the complex oxide of the CF after ₄ copies gas _Al 2 _{O 3} and CaO. It is a schematic view of a rotary kiln used for the production of a composite oxide of al ₂ O ₃ and CaO. Moisture was contained, a schematic view showing a CF ₄ treatment system. Is an XRD chart of the PFC decomposition treatment agent after CF ₄ process including the moisture content 3.26mg / min. The relationship of Table 11 is represented in a graph.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and redundant description is omitted. Further, the present invention is not limited to the following embodiments.

First, with reference to FIG. 1, the structure of the gas processing apparatus 1 which concerns on the 1st Embodiment of this invention is demonstrated. The gas processing apparatus 1 includes a moisture removing apparatus 10 that reduces the amount of moisture in a gas containing PFC and a PFC processing apparatus 20 that decomposes the PFC contained in the gas. As shown in FIG. 1, the moisture removing device 10 is arranged as a pretreatment device for the PFC treatment device 20. This is because the PFC-containing gas introduced into the PFC treatment apparatus 20 may contain a large amount of moisture, and the decomposition treatment agent (Al ₂ O ₃ and CaO combined oxidation) in which such moisture is filled in the PFC treatment apparatus 20. (The details of the composite oxide of Al ₂ O ₃ and CaO will be described later). Therefore, by providing the water removal device 10 as a pretreatment device for the PFC processing device 20, the amount of water contained in the PFC-containing gas generated during actual operation is reduced. In the gas processing apparatus 1, the moisture removing apparatus 10 and the PFC processing apparatus 20 may be a single apparatus configured as an integral unit or may be separate apparatuses. Furthermore, the moisture removing apparatus 10 may be disposed upstream of the PFC processing apparatus 20 with respect to the gas flow, and may not be immediately before the PFC processing apparatus 20.

With reference to FIG. 2, an example in which the gas processing apparatus 1 according to the first embodiment of the present invention is applied in an actual semiconductor manufacturing factory will be described. Exhaust gases discharged from the oxide film etching apparatus 110, the poly silicon etching apparatus 120, and the metal etching apparatus 130, which are semiconductor manufacturing apparatuses, are sucked by the vacuum pump 150 and disposed further downstream. Sent to. In the first dry-type detoxifying device 160, the acidic gas, corrosive gas, and harmful gas contained in the exhaust gas are decomposed by the processing agent filled in the first dry-type detoxifying device 160, or the treating agent. Is removed by adsorption.
In FIG. 2, the moisture removing device 10 is installed downstream of the ashing device 140 that may discharge particularly a large amount of moisture. The exhaust gas discharged from the ashing device 140 and whose moisture content has been reduced by the moisture removing device 10 merges with the exhaust gas discharged from the first dry-type detoxifying device 160 and further sent to the downstream PFC processing device 20. In the PFC processing apparatus 20, the PFC contained in the exhaust gas is decomposed. In FIG. 2, three PFC treatment apparatuses 20 share one moisture removal apparatus 10 to constitute the gas treatment apparatus 1. As described above, the gas processing apparatus 1 may include a plurality of water removal apparatuses 10 or PFC processing apparatuses 20.

  The oxide film etching apparatus 110 is an apparatus that forms an oxide film thin film on a semiconductor wafer and forms a pattern with a photoresist, and then removes an unnecessary thin film by etching. A thin film of crystalline silicon) is used, and a metal thin film is used in the metal etching apparatus 130. The ashing device 140 removes unnecessary resist on the semiconductor wafer after the etching process.

Gases discharged from the oxide film etching apparatus 110 include CF ₄ , CHF ₃ , C ₄ F _{8, and the} like, as well as SiF ₄ , CO, COF ₂ , HF, and the like as by-product gases. Examples of gases discharged from the poly silicon etching apparatus 120 include HBr, Cl ₂ , and CF _4, and SiF ₄ , Br ₂ , HCl, and HF as by-product gases. Examples of the gas discharged from the metal etching apparatus 130 include BCl ₃ , Cl ₂ , and CF _4, and AlCl ₃ as a by-product gas. Examples of gases discharged from the ashing device 140 include CF ₄ , O ₂ , and H ₂ O, and SiF ₄ , HF, and CO as by-product gases.

  With reference to FIG. 3, another example in which the gas processing apparatus 1 according to the first embodiment of the present invention is applied in an actual semiconductor manufacturing factory will be described. In FIG. 3, the exhaust gas discharged from the first dry-type abatement device 160 and the ashing device 140 is once collected in a collecting pipe, and the moisture removing device 10 is installed in the middle of the collecting pipe. Further, one or more PFC processing apparatuses 20 are provided downstream thereof. In the case of FIG. 3 as well, the three PFC processing apparatuses 20 share one moisture removing apparatus 10 to constitute the gas processing apparatus 1.

Hereinafter, the moisture removal device 10, the PFC processing device 20, and the Al ₂ O ₃ as a PFC decomposition treatment agent filled in the PFC processing device 20 included in the gas processing device 1 according to the first embodiment of the present invention. A composite oxide of CaO and CaO will be described.

  First, with reference to FIG. 4 (a), a water removal apparatus 10 constituting the gas processing apparatus 1 according to the first embodiment of the present invention will be described. As the moisture removing device 10, a mist trap 10 a as a cooling means is provided in the middle of a pipe for introducing the PFC-containing gas into the PFC processing device 20. The amount of water contained in the PFC-containing gas is the maximum amount of saturated water vapor. Therefore, the amount of water contained in the PFC-containing gas is reduced by supplying water at a temperature lower than that of the PFC-containing gas to the mist trap to lower the temperature of the PFC-containing gas and reduce the saturated water vapor amount.

As shown to Fig.4 (a), the spray 11 is arrange | positioned inside the mist trap 10a. The cooling water 12 is directly jetted into the PFC-containing gas flowing in the pipe by the spray 11. As a result, the temperature of the PFC-containing gas is lowered, and at the same time, the saturated water vapor amount of the PFC-containing gas is reduced. Therefore, the amount of water contained in the PFC-containing gas falls to the saturated water vapor amount at the temperature after cooling, and the difference between the amount of water contained in the PFC-containing gas before and after cooling is removed as liquid water. be able to. Moreover, since the cooling water 12 is directly jetted to the PFC-containing gas, it is possible to clean the PFC-containing gas.
In addition, as shown in FIG.4 (b), you may use the cooling device 10c using the heat exchanger 14 instead of the mist trap 10a. In this case, the cooling water can be circulated and used, and the cooling water does not come into direct contact with the PFC-containing gas, and the processing load of the waste water containing moisture removed from the PFC-containing gas can be reduced.

When a composite oxide of Al ₂ O ₃ and CaO is used as the decomposition treatment agent of the PFC treatment apparatus 20, as shown in [Test Example 6] described later, the average moisture concentration of moisture contained in the PFC-containing gas Has been found to be desirably 12.4 mg / L (1.29 mg / min) or less. Therefore, when cooling the PFC-containing gas, cool it to a temperature at which the saturated water vapor amount becomes a predetermined concentration, for example, 1.2 mg / min or less, that is, 13 ° C. or less at which the saturated water vapor amount is 11.54 mg / L or less. Is preferred.

  Alternatively, if the cooling water cannot be used due to the layout of the factory, the water adsorption device 10b including the water adsorbent 13 such as silica gel or zeolite is connected to the PFC treatment device 20 with a pipe for introducing the PFC-containing gas. Provided on the way. By allowing the PFC-containing gas to pass through the moisture adsorbing device 10b, the moisture contained in the PFC-containing gas can be brought into contact with and adsorbed with the moisture adsorbent 13, and the amount of moisture in the PFC-containing gas can be reduced. Furthermore, the amount of water in the PFC-containing gas can be more effectively reduced by combining the mist trap 10a or the cooling device 10c with the moisture adsorption device 10b. For example, the PFC-containing gas is once cooled to 20 to 25 ° C. with the mist trap 10a or the cooling device 10c, and then the moisture content is reduced with the moisture adsorption device 10b equipped with the moisture adsorbent 13, whereby heat exchange for cooling water is performed. The capacity of the vessel can be reduced.

As an option, a hygrometer as an abnormality detection means may be installed in the middle of the piping. In addition, when water-soluble gas contained in exhaust gas (PFC-containing gas) discharged from a semiconductor manufacturing device or the like is treated with a wet detoxification device (water scrubber or the like), a large amount of water merges in the PFC-containing gas. Sometimes. In such a case, the service life of the composite oxide of Al ₂ O ₃ and CaO filled in the PFC processing apparatus 20 may be extremely shortened (see [Test Example 6] described later), so that the pipe is in the middle. If a hygrometer or the like is installed in the apparatus and moisture inflow is detected, an alarm or an abnormal signal may be transmitted. In this case, when a highly corrosive gas such as HBr or Cl ₂ is also contained, a hygrometer having corrosion resistance such as coating the surface with a highly corrosion resistant material may be used.

  With reference to FIG. 5, the PFC processing apparatus 20 which comprises the gas processing apparatus 1 which concerns on the 1st Embodiment of this invention is demonstrated. FIG. 5 is a vertical cross-sectional view of the PFC processing apparatus 20, and the PFC processing apparatus 20 decomposes the PFC contained in the gas. The PFC processing apparatus 20 includes an apparatus main body 30 including a rod-shaped internal heater 31 and an external heater 32 arranged in a cylindrical shape at a predetermined interval from the internal heater 31, and includes the internal heater 31 and the external heater 32. Between these, the processing agent arrangement | positioning part 33 which fills with a PFC decomposition processing agent is formed.

More specifically, the PFC processing apparatus 20 includes an apparatus main body 30, a gas introduction pipe 40 for introducing a PFC-containing gas into the apparatus main body 30, and an exhaust pipe 50 for discharging the product gas after reaction from the apparatus main body 30. . The apparatus main body 30 has a cylindrical shape, and a gas introduction portion 38 and a gas discharge portion 39 that are openings for connecting to the gas introduction pipe 40 and the exhaust pipe 50 are formed at both ends of the apparatus main body 30, respectively. Lids 30a and 30b are provided. Further, the treatment agent arrangement portion 33 in the apparatus main body 30 is filled with a composite oxide of Al ₂ O ₃ and CaO.

  The material for forming the lid is not particularly limited, and materials usually used for this type of gas processing apparatus such as stainless steel can be appropriately used.

  A heat insulating material 34 is disposed so as to cover the external heater 32 so that an air layer 35 is formed on the outer periphery of the external heater 32. The heat insulating material 34 is also arranged around the lid bodies 30a and 30b. Thus, by arranging the heat insulating material 34 over the entire outer periphery of the apparatus main body 30, a predetermined interval (air layer 35) between the external heater 32 and the heat insulating material 34 can be opened. .

As a material for forming the heat insulating material 34, ceramic powder (SiO ₂ 60) reinforced with inorganic fibers (SiO ₂ 55%, Al ₂ O ₃ 15%, CaO 17%, B ₂ O ₃ 8%, and other oxides 5%). _{~65%, TiO 2 30~35%,} Al 2 O 3 2~3%, other oxides <1%), and the like.

  The thickness of the air layer 35 is preferably 0.6 to 1 cm.

  In the PFC processing apparatus 20, the internal heater 31 is divided into two in the longitudinal direction to form a first internal heater 31a and a second internal heater 31b. The external heater 32 is divided into two in the longitudinal direction to form a first external heater 32a and a second external heater 32b. The first and second internal heaters 31a and 31b and the first and second external heaters 32a and 32b can be independently temperature controlled.

  Specifically, the first internal heater 31a, the second internal heater 31b, the first external heater 32a, and the second external heater 32b are each connected to a power source (not shown) and supplied from each power source. By controlling the amount of current to be performed, the temperature of each heater can be controlled independently. As described above, the heaters are divided and arranged in the inside and the outer periphery of the treatment agent arranging unit 33, and the temperature inside the apparatus main body 30 can be finely adjusted depending on the place, so that the inside temperature can be made uniform more easily.

  Further, a rectifying plate 37 is disposed in the PFC processing apparatus 20 on the gas introduction part 38 side for introducing the PFC-containing gas. The rectifying plate 37 is preferably a disc-shaped plate having chemical resistance and heat resistance, and is formed of a nickel alloy or a porous material.

Next, a PFC processing method when the PFC processing apparatus 20 is used will be described. As the decomposition treatment agent filled in the PFC treatment apparatus 20, a composite oxide of Al ₂ O ₃ and CaO described later is used.

First, the composite oxide of Al ₂ O ₃ and CaO is filled in the treatment agent placement unit 33 of the PFC treatment apparatus 20. In the present embodiment, Al (OH) ₃ and Ca (OH) ₂ are filled in the apparatus body as in the method described in Patent Document 4, and Al (OH) ₃ , Ca (OH) ₂ and PFC are filled. Relative oxidation of Al ₂ O ₃ and CaO prepared by calcining a mixture of Al (OH) ₃ and Ca (OH) ₂ in advance, instead of contacting the contained gas at a high temperature to remove the PFC-containing gas The processing agent placement unit 33 is filled with the product. In addition, by applying uniform thermal energy to the entire PFC decomposition treatment agent by the internal heater 31 and the external heater 32, the decomposition treatment of the PFC gas proceeds efficiently as compared with the conventional treatment method.

  The PFC-containing gas in which the moisture content is reduced by the moisture removing device 10 is introduced into the device main body 30 from the gas introducing portion 38 through the gas introducing pipe 40.

Next, the PFC-containing gas is uniformly diffused inside the apparatus by contacting the rectifying plate 37. Next, the PFC in the PFC-containing gas comes into contact with the composite oxide of Al ₂ O ₃ and CaO arranged in the treatment agent arrangement unit 33 and is finally decomposed. At this time, while monitoring a plurality of internal temperatures by separately provided sensors (not shown), the amount of current to each of the internal heaters 31a and 31b and the external heaters 32a and 32b is adjusted to control the temperature of each heater. As a result, the temperature inside the apparatus main body 30 is finely adjusted to maintain a uniform temperature.

The treatment temperature at this time is about 550 to about 850 ° C, preferably about 600 to about 850 ° C, and most preferably about 650 ° C to about 750 ° C. When the temperature is less than about 550 ° C., the decomposition rate of CF _{4 in} the PFC decreases, and when the temperature exceeds about 850 ° C., the crystallization of the composite oxide of Al ₂ O ₃ and CaO proceeds gradually, resulting in thermal degradation. .

  Further, although depending on the size of the apparatus main body 30, if the internal capacity of the apparatus main body 30 is 99 liters, the gas introduction rate is 50 to 250 liters / minute in order to perform the processing reaction efficiently. Is preferable.

By the treatment using the composite oxide of Al ₂ O ₃ and CaO, fluorine-containing compounds such as PFC, acid gas, and oxidizing gas in the gas are decomposed. When CO is contained in the PFC-containing gas, or when it is considered that CO is generated by the treatment reaction, oxygen is added to the PFC-containing gas from an oxygen supply pipe (not shown), and the CO in the apparatus main body 30 is Can be simultaneously oxidized to CO ₂ . CO ₂ , H ₂ O and the like generated by the reaction are exhausted through the exhaust pipe 50.

  After the treatment, the residue after the reaction remains in the apparatus main body 30. Fluorine can be produced from calcium fluoride by taking out this, separating and recovering the contained calcium fluoride and treating it with an acid or the like.

Next, with reference to FIG. 2 and FIG. 3, the structure of the gas processing apparatus 2 which concerns on the 2nd Embodiment of this invention, and the gas processing apparatus 3 which concerns on 3rd Embodiment is demonstrated. When the exhaust gas discharged from the semiconductor manufacturing apparatus or the like contains harmful components composed of atoms other than fluorine (for example, HBr, Cl ₂ , BCl _3, etc.), as shown in FIG. 2 and FIG. The dry-type abatement device 160 may be installed separately. As described above, the gas treatment device 2 (see FIG. 2) is disposed on the downstream side of the first dry-type detoxifying device 160 that removes at least one of the acid gas and the corrosive gas, and the first dry-type detoxifying device 160. The PFC processing apparatus 20 decomposes the PFC contained in the gas. Further, the gas treatment device 3 (see FIG. 3) includes the moisture removal device 10 in the gas treatment device 2 on the downstream side of the first dry removal device 160 and on the upstream side of the PFC treatment device 20.
The gas treatment device 2 may include one PFC treatment device 20 and a first dry removal device 160, and the gas treatment device 3 includes the PFC treatment device 20, the first dry removal device 160, and moisture removal. One device 10 may be provided, or a plurality of each device may be provided as shown in FIGS.

The first dry-type abatement apparatus 160 of the present embodiment is an apparatus that does not use water for processing, and does not use a flame or a heater, and it is processed by flowing a gas through a column filled with a processing agent. Say what you do. By introducing a PFC-containing gas from which acid gas or the like has been removed in advance by the first dry-type abatement apparatus 160 that does not use a heater into the PFC processing apparatus 20, a composite oxide of Al ₂ O ₃ and CaO in the PFC processing apparatus 20 Thus, the life of the expensive Al ₂ O ₃ and CaO composite oxide can be extended.

In the first dry-type abatement apparatus 160, synthetic zeolite is used for removing acidic gas such as HBr or corrosive gas. For BCl ₃ and Cl ₂ that cannot be removed by synthetic zeolite, an ion exchange resin, an iron / manganese metal oxide, an alkali agent made of Ca (OH) ₂ , or activated carbon is used. In addition, when the PFC-containing gas includes a plurality of the above-described compositions, when the first dry-type abatement apparatus 160 in which the above-described synthetic zeolite, ion exchange resin, metal oxide, alkali agent, and activated carbon are appropriately combined is installed. Good. Regarding the CO, it can be also treated with a complex oxide of _Al 2 _{O 3} and CaO filled in PFC processing apparatus 20.

If the first dry-type abatement apparatus 160 is arranged on the upstream side of the PFC processing apparatus 20, boron particles generated from BCl ₃ can be removed before the PFC processing apparatus 20. Therefore, it is possible to prevent solids such as boron particles from being mixed in the PFC treatment apparatus 20 and the active points of the decomposition treatment agent being covered by the solids, thereby reducing the performance. Furthermore, it is possible to prevent gas from becoming difficult to flow through the PFC processing apparatus 20 due to clogging by particles.

  2 and 3, the first dry-type abatement device 160 is individually connected to each of the semiconductor manufacturing apparatuses 110 to 130, but the exhaust gas (PFC-containing gas) from each of the apparatuses 110 to 140 is collected into a collective pipe. A common first dry-type abatement device 160 may be provided downstream thereof. Further, the order of the first dry-type abatement device 160 and the water removal device 10 may be switched. In addition, when water | moisture content is taken with adsorption agents, such as a silica gel, if the water removal apparatus 10 is installed in the downstream of the 1st dry-type abatement apparatus 160, it can prevent that a water | moisture-content adsorption agent breaks through with acidic gas.

Next, with reference to FIG. 6, the structure of the gas processing apparatus 4 which concerns on the 4th Embodiment of this invention is demonstrated. As shown in FIG. 6, the gas processing apparatus 4 further includes a second dry-type abatement apparatus 170 in addition to the configuration of the gas processing apparatus 2 (see FIG. 2). The second dry-type abatement apparatus 170 decomposes a part of PFC (for example, CH ₃ F, C ₂ F _4, etc.) that can be processed at a temperature lower than the processing temperature in the PFC processing apparatus 20 as a preprocessing. By reducing the amount of PFC in the PFC-containing gas, the load of the composite oxide of Al ₂ O ₃ and CaO filled in the PFC processing apparatus 20 is reduced. As a result, the service life as a decomposition treatment agent for the composite oxide of Al ₂ O ₃ and CaO can be further extended.

For example, the second dry-type abatement apparatus 170 is filled with an Fe—Mn metal oxide as a treatment agent. By using the Fe—Mn-based metal oxide, CH ₃ F can be decomposed in a temperature range of 200 to 300 ° C. in the PFC. Moreover, C ₂ F ₄ can be decomposed at around 100 ° C.
As described above, the second dry-type abatement apparatus 170 removes PFC that can be decomposed at a temperature lower than the processing temperature (about 550 to about 750 ° C.) of the PFC processing apparatus 20 from the PFC-containing gas as a pretreatment. .

  Therefore, as shown in FIG. 6, the second dry abatement apparatus 170 is downstream of the first dry abatement apparatus 160 and upstream of the PFC treatment apparatus 20 with respect to the flow of the PFC-containing gas. Placed in. With this arrangement, when at least one of acid gas and corrosive gas is contained in the PFC-containing gas, after removing these harmful gases, a part of the PFC treatment apparatus 20 is pretreated. It is preferable because PFC can be removed.

  Note that the second dry-type abatement apparatus 170 of the present embodiment is an apparatus that does not use water for the treatment, but unlike the first dry-type abatement apparatus 160, it has a heating device, and is treated. This means that the PFC-containing gas is flowed through the column filled with the agent.

  Below, the structure of the 2nd dry-type abatement apparatus 170 is demonstrated. The second dry-type abatement device 170 may be a device separated from the first dry-type abatement device 160 as shown in FIG. 6, or the first dry-type abatement device 170 as shown in FIG. An apparatus integrated with the dry-type abatement apparatus 160 may be used. Alternatively, as shown in FIG. 8A, the second dry-type abatement apparatus 170 may be an apparatus integrated with the PFC processing apparatus 20.

  With reference to Fig.7 (a), the case where the 2nd dry-type abatement apparatus 170 is formed integrally with the 1st dry-type abatement apparatus 160 is demonstrated. The first dry-type abatement apparatus 160 has a cylindrical column 161. The second dry-type abatement apparatus 170 has a double-structured cylindrical column, and the inner column 171 is connected to the column 161. The outer surface of the column 171 is covered with a column 172 having a larger diameter than the column 171, and a space a is formed by the column 171 and the column 172. The column 161 and the column 171 can be distinguished from each other by forming two layers with the processing agent filled therein. Alternatively, a porous mesh member 200 in which gas passage holes are formed may be disposed at the boundary between the column 161 and the column 171. In order to prevent the porous mesh member 200 from being clogged with powdery substances contained in the treatment agent, an alumina ball (for example, 3/8 inch alumina) having a diameter larger than that of the treatment agent is provided in the vicinity of the mesh member 200. Ball) or an alumina cylinder ring.

As shown in FIG. 7A, the PFC-containing gas is first introduced into the first dry removal apparatus 160 from a pipe (not shown) connected to the first dry removal apparatus 160. Acidic gas or the like contained in the PFC-containing gas is removed at room temperature by the processing agent 166 (for example, synthetic zeolite) packed in the column 161. Next, the PFC-containing gas from which the acid gas or the like has been removed flows into the column 171 of the second dry-type abatement apparatus 170. CH ₃ F or the like in the PFC-containing gas is decomposed and removed at a temperature of 300 ° C. or lower (but higher than normal temperature) by the treatment agent 176 (Fe—Mn-based metal oxide) packed in the column 171. Further, the PFC-containing gas from which CH ₃ F and the like have been removed is introduced into the PFC processing apparatus 20. PFC in the PFC-containing gas is decomposed and removed at a temperature of 550 to 750 ° C. by the treatment agent 36 (a composite oxide of Al ₂ O ₃ and CaO) filled in the PFC treatment apparatus 20. Further, the gas discharged from the PFC processing apparatus 20 is introduced into the space a formed by the column 171 and the column 172 of the second dry-type abatement apparatus. Therefore, the treatment agent 176 packed in the column 171 can be heated by the waste heat of the gas heated to 550 to 750 ° C. Thus, the space a into which the gas discharged from the PFC processing apparatus 20 is introduced functions as a heating apparatus. In addition, you may provide the heat-transfer fin 175 for improving heat conduction inside the space a.

In addition, if the 1st dry-type abatement apparatus 160 and the 2nd dry-type abatement apparatus 170 which were formed integrally are comprised in the PFC processing apparatus 20 and one box, the heat of the gas discharged | emitted from the PFC processing apparatus 20 Is preferable because it is possible to suppress the loss of water. In the second dry-type abatement apparatus 170, an internal heater 31 (not shown in FIG. 7A) as shown in FIG.
Further, in FIG. 7A, gas is sucked from the semiconductor manufacturing apparatus or the like by the vacuum pump 150, and the flow of the gas is changed from the first dry removal apparatus 160 to the second dry removal apparatus 170 (column 171). → PFC treatment device 20 → second dry abatement device 170 (space a).

  Alternatively, as shown in FIG. 7B, the second dry-type abatement apparatus 170 may form a double-pipe column 173 having a smaller diameter than the column 171 inside the column 171. In this case, the treatment agent 176 is filled in the space formed by the columns 171 and 173. Further, by introducing the gas discharged from the PFC processing apparatus 20 into the space b inside the column 173, the processing agent 176 is heated by the waste heat of the gas discharged from the PFC processing apparatus 20. That is, the space b functions as a heating device. If the column 173 has a double-pipe structure and an inner tube 174 is installed at the center of the space b so that the gas is discharged from the space b after passing through the inner tube 174, the interior of the space b can be sufficiently obtained. Since gas can be introduced, it is preferable. Furthermore, the processing agent 176 may be heated by providing an external heater 32 as another heating device on the outer surface of the column 171.

With reference to Fig.8 (a), the structure in which the 2nd dry-type abatement apparatus 170 was integrally formed with the PFC processing apparatus 20 is demonstrated. In the PFC processing apparatus 20 shown in FIG. 5, the external heater 32 is divided into two in the longitudinal direction. However, in FIG. 8A, the external heater 32 is divided into three, and the PFC-containing gas introduction side serves as a heating apparatus. A third external heater 32c is formed. Similarly, the internal heater 31 shown in FIG. 5 (not shown in FIG. 8A) may be divided into three in the longitudinal direction.
Furthermore, the second dry-type abatement apparatus 170 and the PFC processing apparatus 20 are each configured in a manner in which one apparatus main body 30 is divided. A region heated by the external heater 32 c of the apparatus main body 30 is filled with a processing agent 176 (Fe—Mn metal oxide). A region heated by the external heaters 32 a and 32 b of the apparatus main body 30 is filled with a processing agent 36 (a composite oxide of Al ₂ O ₃ and CaO). As described above, the second dry-type abatement apparatus 170 includes a part of the apparatus main body 30 and the external heater 32c, and the PFC processing apparatus 20 includes the other part of the apparatus main body 30 and the external heaters 32a and 32b.

In addition, the inside of the processing agent arrangement | positioning part 33 of the apparatus main body 30 can be distinguished into the 2nd dry-type abatement apparatus 170 and the PFC processing apparatus 20 by filling the processing agent 176 and the processing agent 36 into two layers. Or you may install the porous mesh member 200 in which the gas passage hole was formed in the boundary of the processing agent 176 and the processing agent 36. FIG.
If comprised in this way, since the heater structure can be shared by the 2nd dry-type abatement apparatus 170 and the PFC processing apparatus 20, the apparatus can be miniaturized. Furthermore, since the PFC-containing gas heated by the second dry-type abatement apparatus 170 can be introduced into the PFC processing apparatus 20 as it is, the processing agent 36 can be efficiently heated with little heat loss.

As shown in FIG. 8A, the PFC-containing gas is first introduced into the first dry removal layer apparatus 160 from a pipe (not shown) connected to the first dry removal apparatus 160. Acidic gas or the like contained in the PFC-containing gas is removed at normal temperature by the treatment agent 166 (for example, synthetic zeolite) filled in the first dry-type detoxifying layer device 160. Next, the PFC-containing gas from which the acid gas or the like has been removed flows into the second dry-type abatement apparatus 170. CH ₃ F and the like in the PFC-containing gas are decomposed at a temperature of 300 ° C. or lower (higher than normal temperature) by the treatment agent 176 (Fe—Mn-based metal oxide) filled in the second dry-type detoxifying device 170. Removed. Further, the PFC-containing gas from which CH ₃ F and the like have been removed is introduced into the PFC processing apparatus 20. PFC in the PFC-containing gas is decomposed and removed at a temperature of 550 to 750 ° C. by the treatment agent 36 (a composite oxide of Al ₂ O ₃ and CaO) filled in the PFC treatment apparatus 20.

Alternatively, as shown in FIG. 8B, a cylindrical inner tube 21 may be formed in the device main body 30 so that the second dry-type abatement device 170 has a double tube structure. In this case, the processing agent 176 is filled inside the inner tube 21, and a space c is formed by the inner tube 21 and the apparatus main body 30. As described above, the second dry-type abatement apparatus 170 includes a part of the apparatus main body 30 and the inner tube 21.
Further, a cylindrical inner tube 22 having a diameter smaller than that of the inner tube 21 is formed in the apparatus main body 30 so that the PFC processing apparatus 20 has a double tube structure. In this case, the processing agent 36 is filled outside the inner tube 22. As described above, the PFC processing apparatus 20 includes the other part of the apparatus main body 30, the inner tube 22, and the heaters 32a and 32b. The inner pipe 22 is connected to the inner pipe 21 and guides the gas discharged from the inner pipe 21 to the inside of the apparatus main body 30 of the PFC processing apparatus 20.
Further, the boundary between the inner space of the inner tube 21 and the inner space of the inner tube 22 and the boundary between the processing agent placement portion 33 filled with the processing agent 36 and the space c are porous in which gas passage holes are formed. The mesh member 200 is partitioned.

As shown in FIG. 8B, the PFC-containing gas is first introduced into the first dry-type detoxifying layer apparatus 160 from a pipe (not shown) connected to the first dry-type detoxifying apparatus 160. Acidic gas or the like contained in the PFC-containing gas is removed at normal temperature by the treatment agent 166 (for example, synthetic zeolite) filled in the first dry-type detoxifying layer device 160. Next, the PFC-containing gas from which the acid gas or the like has been removed flows into the inner pipe 21 of the second dry-type abatement apparatus 170. CH ₃ F or the like in the PFC-containing gas is decomposed and removed at a temperature of 300 ° C. or lower (but higher than normal temperature) by the treatment agent 176 (Fe—Mn metal oxide) filled in the inner tube 21. Further, the PFC-containing gas from which CH ₃ F and the like have been removed flows through the inner pipe 22 and into the processing agent placement unit 33 of the PFC processing apparatus 20. The PFC in the PFC-containing gas is decomposed and removed at a temperature of 550 to 750 ° C. by the processing agent 36 (a composite oxide of Al ₂ O ₃ and CaO) filled in the processing agent arrangement portion 33 of the PFC processing apparatus 20. . Thereafter, the gas from which the PFC is decomposed and removed at a temperature of 550 to 750 ° C. flows into the space c formed in the second dry-type abatement apparatus 170. Thus, the processing agent 176 is heated by the waste heat of the gas discharged from the PFC processing apparatus 20. That is, the space c functions as a heating device. Thus, since the gas heated by the PFC processing apparatus 20 can be introduced into the second dry-type detoxifying apparatus 170 as it is, the processing agent 176 can be efficiently heated with little heat loss. In the second dry-type abatement apparatus 170, an internal heater 31 (not shown in FIG. 8B) as shown in FIG.

  Next, with reference to FIG. 9, the structure of the gas processing apparatus 5 which concerns on the 5th Embodiment of this invention is demonstrated. The gas processing device 5 further includes a moisture removing device 10 in addition to the gas processing device 4. As shown in FIG. 9, the PFC-containing gases from the second dry-type detoxifying device 170 may be combined into a collecting pipe, and a shared moisture removing device may be installed downstream thereof. Alternatively, the water removal device 10 may be installed downstream of the first dry removal device 160 and upstream of the second dry removal device 170. That is, it is preferable that the moisture removing apparatus 10 is disposed at a position where moisture in the gas can be removed as a pretreatment of the PFC processing apparatus 20 with respect to the flow of the PFC-containing gas. Further, although one water removing device 10 is arranged in FIG. 9, a plurality of water removing devices 10 may be provided.

In addition, when the exhaust gas discharged from the semiconductor manufacturing apparatus or the like does not contain harmful components composed of atoms other than fluorine (for example, HBr, Cl ₂ , BCl _3, etc.) or is in a trace amount, the gas processing apparatus 4 ( In the gas processing apparatus 5 (see FIG. 6) and the gas processing apparatus 5 (see FIG. 9), the first dry-type abatement apparatus 160 may not be included. In this case, the processing temperature of the second dry-type abatement apparatus 170 is maintained at a relatively low temperature (350 ° C. or lower), and the easily decomposable PFC is decomposed and removed. Subsequently, the processing temperature of the PFC processing apparatus 20 is maintained at a relatively high temperature (550 to 750 ° C.), and the hardly decomposable PFC is decomposed and removed.

Hereinafter, a composite oxide of Al ₂ O ₃ and CaO as a PFC decomposition treatment agent filled in the PFC treatment apparatus 20 will be described in detail.
The PFC decomposition treatment agent filled in the treatment agent placement unit 33 (see FIG. 5) of the PFC treatment apparatus 20 includes Al (OH) ₃ having an average particle diameter (median diameter) of 55 μm or more and 160 μm or less, and Ca (OH) _2. A composite oxide of Al ₂ O ₃ and CaO obtained by baking a mixture having a molar ratio of from 3: 7 to 5: 5 in a nitrogen flow or an air flow in a temperature range of 430 ° C. to 890 ° C. Used.
Alternatively, a mixture in which the molar ratio of Al (OH) ₃ having an average particle diameter (median diameter) of 60 μm to 160 μm and Ca (OH) ₂ is 3: 7 to 5: 5 is a temperature of 430 ° C. to 890 ° C. In range, a composite oxide of Al ₂ O ₃ and CaO obtained by firing in a nitrogen flow or air flow is used. In addition, it is preferable that a calcination temperature is the same as or lower than the treatment temperature at which the PFC-containing gas is treated with a composite oxide of Al ₂ O ₃ and CaO.

The composite oxide of Al ₂ O ₃ and CaO functions as a “PFC decomposing agent” and a “fluorine fixing agent” in the present application. In the following, the former means that the PFC is decomposed, and the latter is further used as a concept including the further recovery of fluorine as a solid such as CaF ₂ . However, the constituent components of the “PFC decomposition agent” and the “fluorine fixing agent” are the same. When both are included, that is, when it is intended to decompose the PFC and fix it with fluorine, the “PFC decomposition treatment” And “PFC decomposition treatment agent”.

[Raw material of composite oxide of Al ₂ O ₃ and CaO]
Al (OH) ₃ which is a raw material of the composite oxide of Al ₂ O ₃ and CaO has an average particle size of 55 μm or more, preferably 60 μm or more and 160 μm or less, more preferably 90 μm or more and 120 μm or less. Here, the average particle diameter means the median diameter, and is the particle diameter at which the frequency (content) is integrated for each particle diameter, and the accumulation of the content reaches 50% from the minimum particle diameter. In measuring the median diameter, laser diffraction / scattering method is used and D50 is measured on a volume basis. As other measurement methods, specific surface area / pore distribution measurement by gas adsorption method, pore distribution measurement by mercury intrusion method, and dry density measurement by constant volume expansion method may be used.

If the average particle size is outside the above range, the desired treatment performance as a PFC decomposition treatment agent cannot be obtained, and the CF ₄ removal rate deteriorates to 95% or less in a short time as will be described later in the test examples. Unbearable for practical use.

Al ₂ O ₃ and although the raw material Ca (OH) ₂ having an average particle diameter which is a composite oxide of CaO varies depending on the average particle size of _{Al (OH) 3, Al (} OH) 3 than Ca (OH) ₂ The average particle diameter (median diameter) is preferably smaller. The average particle diameter (median diameter) of Ca (OH) ₂ is preferably 1 μm to 10 μm, more preferably 3 μm to 8 μm, and most preferably 4 μm to 6 μm.

Al (OH) ₃ and Ca (OH) ₂ have Al (OH) ₃ having a large average particle diameter as a nucleus, and the activity is maintained by efficiently arranging Ca (OH) _{2 on the} surface layer. it is conceivable that. Thus, Ca (OH) ₂ of the particle size is too small compared to the average particle size of Al (OH) ₃ Al a (OH) the entire surface of the ₃ cover without gaps, consequently by preventing contact between the PFC Inhibiting the decomposition of PFC, conversely, if the Ca (OH) ₂ particle size is too large compared to the average particle size of Al (OH) ₃ , the contact efficiency with F during PFC decomposition is reduced, resulting in decomposition. In any case, it is considered that the PFC decomposition efficiency is lowered.

The molar ratio of Al (OH) ₃ and Ca (OH) ₂ in the above mixture is 3: 7 to 5: 5, preferably 3: 7 to 4: 6. If the molar ratio of Al (OH) ₃ and Ca (OH) ₂ is outside the above range, the desired processing performance as a PFC decomposition treatment agent cannot be obtained, and as will be described later in the test examples, the CF can be obtained in a short time. _{4 The} removal rate deteriorates to 95% or less, and cannot be practically used.

[Method for preparing composite oxide of Al ₂ O ₃ and CaO]
The composite oxide of Al ₂ O ₃ and CaO is a mixture of the above mixture in a temperature range of 430 ° C. to 890 ° C., preferably 580 ° C. to 850 ° C., more preferably 650 ° C. to 780 ° C. Obtained by firing in a stream.

The firing temperature of the mixture of Al (OH) ₃ and Ca (OH) ₂ needs to be a temperature that allows dehydration and does not deactivate. Since the dehydration temperature of Al (OH) ₃ is about 270 ° C. and the dehydration temperature of Ca (OH) ₂ is about 430 ° C., it is preferably at least 430 ° C. or higher. When the temperature range exceeds 890 ° C., the CF ₄ removal rate decreases as will be described later with reference to test examples. This is considered to be due to the fact that the aluminum oxide crystallizes due to the high heat treatment and the activity deteriorates. In addition, it is preferable that a calcination temperature is the same as or lower than the treatment temperature at which the PFC-containing gas is treated with a composite oxide of Al ₂ O ₃ and CaO.

A mixture of Al (OH) ₃ and Ca (OH) ₂ is calcined in a stream of nitrogen or air. The flow of nitrogen or air preferably reverses the inflow direction for a certain time. This is because moisture generated as a result of the dehydration reaction that proceeds by firing does not stay around the mixture, but quickly evaporates and leaves. If the mixture of Al (OH) ₃ and Ca (OH) ₂ is continuously fired in a hot and humid atmosphere, the presence of moisture causes the aluminum oxide to crystallize (meaning crystallization at the fine structure level at the active site). It is thought that the activity deteriorates. Therefore, it is necessary to quickly remove the generated moisture by flowing an inert gas around Al (OH) ₃ or aluminum oxide obtained by firing. The countercurrent airflow of nitrogen flow or air flow is given by, for example, filling a column with a mixture of Al (OH) ₃ and Ca (OH) ₂ and sending nitrogen flow or air flow from above and below the column. Can do.

The firing time is not particularly limited, and varies depending on the amount of Al (OH) ₃ and Ca (OH) ₂ used, but generally 6 to 12 hours is the point of dehydration effect and energy consumption efficiency. Preferably, the time is 8 to 10 hours. Technically, it is considered sufficient to raise the temperature to a temperature at which Ca (OH) ₂ is dehydrated (about 430 ° C.) and then calcinate for 1-2 hours. If the rate of temperature rise until reaching the firing temperature is too fast, dehydration may be insufficient, and if it is too slow, it is not preferred for economic reasons (consuming energy and time). Usually, a temperature increase rate of 100 ° C./hr is optimum. Also, if the firing time is too long, the PFC decomposition treatment agent is excessively adsorbed with CO ₂ generated from the fuel during firing, and the fluorine adsorption performance is lowered, which is not preferable.

The composite oxide of Al ₂ O ₃ and CaO obtained by the above preparation method is a composite oxide of amorphous Al ₂ O ₃ and CaO as shown by XRD (X-ray diffraction) analysis described later. The content ratio of amorphous Al ₂ O ₃ and CaO in the composite oxide is a molar ratio of Al ₂ O ₃ : CaO = 1: 10.5 to 1: 12.5. From the viewpoint of maintaining the activity, it is more preferably 1: 10.5 to 1:12.

[Characteristics of composite oxide of Al ₂ O ₃ and CaO]
Further, the Al ₂ O ₃ and CaO composite oxide obtained by the above production method preferably has a moisture content lower than 5 wt%, more preferably 0.8 wt% or more and 5 wt% or less, and 1.5 wt%. % To 3.5 wt% is more preferable. Most preferably, it is 2.7 wt% or less. As the water content increases, the CF ₄ removal rate decreases as will be described later. Conventionally, it is thought that the higher the moisture content, the higher the CF ₄ removal rate. Considering that moisture was added during the treatment of fluorine-containing workpieces, the lower the moisture content in this PFC decomposition treatment agent, The finding that the CF ₄ removal rate is high is specific.

A heat resistance improver can be further mixed with the PFC decomposition treatment agent of the present application. Preferable examples of the heat resistance improver include ZrO ₂ and La. The blending ratio of the heat resistance improver is preferably 0.01 to 0.5 mol with respect to 1 mol of Al (OH) ₃ , more preferably 0.05 to 0 with respect to 1 mol of Al (OH) _3. .4 mole, and most preferably 0.08 to 0.35 mole relative to 1 mole of Al (OH) ₃ . When the blending ratio of the heat resistance improver is out of the above range, the crystallization of the PFC decomposition treatment agent gradually proceeds at the use temperature, and it becomes difficult to maintain the activity over a long period of time.

In the PFC decomposition treatment agent of the present application, the Na content in the baked product of a mixture of Al (OH) ₃ and Ca (OH) ₂ is preferably 0.03 wt% or less. If Na is present in a large amount, Na + is selectively adsorbed on the active sites that cause the PFC decomposition action, which is not preferable because the PFC decomposition reaction is inhibited.

The PFC decomposition treatment agent of the present application can be further mixed with an oxidizing power improvement aid. Preferable examples of the oxidizing power improving aid include Pd, Pt, Rh, Ru. The blending ratio of the oxidizing power improving aid is preferably 0.005 to 0.1 mol with respect to 1 mol of Al (OH) ₃ , and more preferably 0.01 to 0.1 mol with respect to 1 mol of Al (OH) _3. The amount is 0.07 mol, and most preferably 0.02 to 0.05 mol with respect to 1 mol of Al (OH) ₃ . When the blending ratio of the oxidizing power enhancing aid is outside the above range, decomposition of C ₂ F ₆ or C ₄ F ₈ having a large number of carbon atoms in the PFC does not proceed, and the removal performance starts to decrease relatively early.

Examples of the fluorine-containing compound that can be treated with the PFC decomposition treatment agent of the present application include perfluoro compounds such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , and NF _3. . Examples of such a gas containing a perfluoro compound (PFC) include exhaust gas discharged in a process of dry-cleaning the inner surface of a semiconductor manufacturing apparatus or a process of etching various film formations in the semiconductor industry.

Further, the PFC decomposition treatment agent of the present application can also decompose oxidizing gas, acidic gas, etc. in addition to PFC and the like. In the exhaust gas discharged from the semiconductor manufacturing process, not only PFC but also oxidizing gases such as F ₂ , Cl ₂ , Br ₂ , HF, SiF ₄ , COF ₂ , HCl, HBr, SiCl ₄ , SiBr _{4 are used.} And so on. Conventionally, there are wet processing methods for oxidizing gases such as F ₂ , Cl ₂ , and Br ₂ , but they cannot be processed completely with water alone, and management and equipment are complicated because an alkali agent and a reducing agent are used in combination. In addition, there are problems such as cost. According to the PFC decomposition treatment agent, these oxidizing gas and acidic gas can also be decomposed together with a fluorine-containing compound such as PFC.

[Structure and reaction of composite oxide of Al ₂ O ₃ and CaO]
The composite oxide of Al ₂ O ₃ and CaO is considered to be loosely bonded through oxygen as follows.

When a composite oxide of Al ₂ O ₃ and CaO is brought into contact with a fluorine compound, CF ₄ → C + 4F is caused by the catalytic action of the (Al_O) portion.
As the decomposition reaction proceeds, oxygen (O) and calcium (Ca) from the (O_Ca) portion cause C + 2O → CO ₂
4F + 2Ca → 2CaF ₂
It is thought that the redox reaction proceeds.

Thus, when an exhaust gas containing a fluorine-containing compound is treated using a composite oxide of Al ₂ O ₃ and CaO, PFC is decomposed and an intermediate product such as HF is not generated in the course of the reaction. Calcium hydride (CaF ₂ ) is produced. Calcium fluoride is a main component of fluorite known as a raw material for producing fluorine, and fluorine gas can be generated by treatment with acid. Therefore, when a composite oxide of Al ₂ O ₃ and CaO is used, fluorine can be recovered in a reusable form from a gas containing a fluorine-containing compound very efficiently.

In addition, a method for recovering fluorine from a gas to be treated containing a fluorine-containing compound is provided, which comprises contacting a composite oxide of Al ₂ O ₃ and CaO with a gas to be treated containing a fluorine-containing compound. At this time, it is preferable to contact the composite oxide of Al ₂ O ₃ and CaO and the gas to be treated containing the fluorine-containing compound at a temperature of 550 ° C. to 850 ° C., more preferably in the range of 600 to 800 ° C. About 650 ° C. to 750 ° C. is most preferred.

Hereinafter, the composite oxide of Al ₂ O ₃ and CaO will be described more specifically.
[Test Example 1]

[PFC decomposition treatment agent A]
Each of the following preparation examples adopted a preparation method in which the generated moisture was quickly discharged from the baking vessel and the contact between the mixture of Al (OH) ₃ and Ca (OH) ₂ and moisture was avoided.

As shown in FIG. 10, a mixture of Al (OH) ₃ and Ca (OH) _{2 in} a small column (dimension: diameter 150 mm × height 850 mm) equipped with an external heater around the circumference so that it can be heated uniformly. (Al (OH) ₃ average particle diameter 90 μm, Ca (OH) ₂ average particle diameter 5 μm, Al (OH) ₃ and Ca (OH) ₂ mixing ratio 3: 7) a large amount of N ₂ so as steam does not stay flow rate: received 50L / min in the upflow and downflow. By adjusting the temperature of the external heater, and fired at first by flowing N ₂ upflow 5-6 hours Al (OH) ₃ and Ca (OH) ₂ and half the upper of the mixture layer of 420 ° C. or higher Next, N ₂ downward flow was allowed to flow for 2 to 3 hours, and the lower half of the mixture layer of Al (OH) ₃ and Ca (OH) ₂ was fired to 420 ° C. or higher. In the above adjustment method, the molar ratio of Al (OH) ₃ and Ca (OH) ₂ is 3: 7. 1-1.

Table 1 shows the results of measuring the water content and the CF ₄ removal rate for the PFC decomposition treatment agent A obtained at each firing temperature. CF ₄ removal rate, gas processing system shown in FIG. 13 the PFC decomposition agent 49 ml (where minicolumns were only first cylinder th) was charged into a mini-column (diameter 22 mm × height 300 mm) of, CF ₄ flow into The removal rate after passing gas at a concentration of 1.0%, a gas flow rate of 410 ml / min, and a processing temperature of 750 ° C. for 3 hours was determined. Sample No. 1-0 means a mixture of Al (OH) ₃ and Ca (OH) ₂ before firing. A concentration of 1.0% means volume percent.

焼成温度は、充填されたＡｌ(ＯＨ)_３とＣａ(ＯＨ)_２との混合物層の温度を内部に挿入した熱電対により実測した値である。また、表中の記号「＞」は、例えば９９．９％を超えることを示す（以下同様）。 Table 1 shows the relationship between the firing temperature, the water content, and the CF ₄ removal rate.

The firing temperature is a value obtained by actually measuring the temperature of the filled mixture layer of Al (OH) ₃ and Ca (OH) ₂ with a thermocouple inserted therein. Moreover, the symbol “>” in the table indicates, for example, that it exceeds 99.9% (the same applies hereinafter).

From Table 1, the moisture content is reduced to 12 wt% even at 420 ° C., but since the dehydration temperature of Ca (OH) ₂ is about 430 ° C., it is preferably at least 430 ° C. or more, and 500 ° C. or more. It turns out that it is more preferable. Further, it can be seen that at a firing temperature of 910 ° C., the CF ₄ removal rate decreases to 96.8% when the water content is 1.6 wt%. This seems to be the effect of thermal degradation.

From Table 1, it can be seen that the firing temperature is preferably 580 ° C to 780 ° C. The PFC decomposition treatment agent fired at a firing temperature of 600 ° C. in consideration of the firing treatment cost was further examined for the relationship between the water content and the CF ₄ removal rate.

A mixture of Al (OH) ₃ and Ca (OH) ₂ (average particle diameter of Al (OH) ₃ of 90 μm, average particle diameter of Ca (OH) ₂ of 5 μm, Al (OH) ₃ and Ca (OH) ₂ A mixing ratio (3: 7) in a molar ratio was filled into a minicolumn (diameter 22 mm × height 300 mm), and this was attached to a ceramic tube furnace, and the temperature was raised to 600 ° C. while feeding nitrogen at 410 ml / min. The moisture adjustment was performed by adjusting the firing time. Specifically, a PFC decomposition treatment agent having a moisture content of 2.7 wt% at a firing time of 5 hours, a moisture content of 1.6 wt% at a firing time of 11 hours, and a moisture content of 0.8 wt% at a firing time of 24 hours is obtained. It was.

49 ml each of the PFC decomposition treatment agents 1-8 to 1-10 thus obtained were packed in a minicolumn of the gas treatment system shown in FIG. 13 (however, the minicolumn was only the first cylinder), and the CF ₄ inflow concentration: 1 0.0%, gas flow rate: 410 ml / min, treatment temperature: 750 ° C., gas was passed for 5 hours (after CF ₄ gas was discharged 3 hours later, the supply of CF ₄ was stopped, and the temperature of nitrogen was raised (410 ml / min with nitrogen alone, 750 ° C.) was performed for 12 hours, and then CF ₄ gas out (CF ₄ inflow concentration: 1.0%, gas flow rate: 410 ml / min, treatment temperature: 750 ° C.) was resumed for 2 hours. According to this, both the initial performance and the lifetime can be evaluated.) The CF ₄ removal rate was obtained. The results are shown in Table 2.

From Table 2, it can be seen that there is no significant difference between the water content of 0.8 wt% and 2.7 wt%, and a high CF ₄ removal rate is achieved even when the water content is 1 wt% or less.
FIG. 14 shows an XRD analysis chart of the obtained PFC decomposition treatment agent (sample No. 1-3 in Table 1). The upper peak data is an analysis peak from raw data of the obtained PFC decomposition treatment agent (sample No. 1-3), and the lower card peak is a characteristic peak of CaO from library data. The peak of the obtained PFC decomposition treatment agent (sample No. 1-3) completely coincides with the library data peak of CaO. As a reference, FIG. 15 shows a standard X-ray diffraction spectrum of crystalline alumina, but no characteristic peak of Al ₂ O ₃ is observed in the PFC decomposition treatment agent (sample No. 1-3) obtained above. Further, in contrast to the observation of the peak of Ca (OH) ₂ in the XRD chart of the comparative example described later, it can be said that the entire amount of Ca (OH) ₂ is changed to CaO by firing. From these facts, it is considered that the PFC decomposition treatment agent of the present application does not generate crystalline Al ₂ O ₃ because all the water generated by firing is removed and the hydrothermal reaction does not proceed.
[PFC decomposition treatment agent B]
As shown in FIG. 11, by using a direct combustion furnace having a storage shelf inside the box, a mixture of Al (OH) ₃ and Ca (OH) ₂ is spread on each storage shelf to a thickness of 10 mm and 20 kg. Then, air is flowed at 20 m ₃ / min, the temperature is increased to 600 ° C. over 6 hours at a temperature increase rate of 100 ° C./hr, and further calcined at 600 ° C. for 6 hours. Obtained. The obtained PFC decomposition treatment agent B had a water content of 2.8 wt%.

The PFC decomposition agent gas treatment system shown in FIG. 13 to 49ml of B (where minicolumns were only first cylinder th) was charged into a mini-column (diameter 22 mm × height 300 mm) of, CF ₄ concentration of inflow: 1. The CF ₄ removal rate after gas was passed through for 3 hours at 0%, gas flow rate: 410 ml / min, treatment temperature: 750 ° C., showed a high removal rate of 99.9% or more.
[PFC decomposition treatment agent C]
As shown in FIG. 20, the rotary kiln has a cylindrical inner cylinder (diameter: about 60 cm × length: 4 to 5 m) having an inlet on one side and an outlet on the opposite side. A heater is installed with a gap provided on the half circumference without contacting the inner cylinder. The inner cylinder has a gentle downward slope from the inlet to the outlet, and the charged agent is moved to the outlet by rotating the inner cylinder. During the movement, the agent is indirectly heated inside the inner cylinder heated by the heater. Gas is not forcedly fed into the inner cylinder, and the air is naturally sucked from the discharge port by the rising gas flow generated inside, and is exhausted in the direction opposite to the flow of the agent. . In such a rotary kiln, a mixture of Al (OH) ₃ and Ca (OH) ₂ (average particle diameter of Al (OH) ₃ is 90 μm, average particle diameter of Ca (OH) ₂ is 5 μm, Al (OH ) ₃ and Ca (OH) ₂ in a molar ratio of 3: 7) was added in an amount of 20 kg / min, and calcined at 620 ° C. ± 20 ° C. for about 1 hour to obtain a PFC decomposition treatment agent C. It was. Over-adsorption of CO ₂ generated from fuel was avoided by heating indirectly using a rotary kiln. The obtained PFC decomposition treatment agent C had a water content of 2.6 wt%.

49 ml of this PFC decomposition treatment agent C is packed into a minicolumn of the gas treatment system shown in FIG. 13 (however, the minicolumn is only the first cylinder), CF ₄ inflow concentration: 1.0%, gas flow rate: 410 ml / min, treatment temperature: CF ₄ removal rate after passing through gas at 750 ° C. for 3 hours was found to be as high as 99.9% or higher.
[PFC decomposition test]
A PFC decomposition treatment agent (sample No. 1-3 in Table 1) calcined with a [PFC decomposition treatment agent A] by a mini-column is filled in a gas treatment device shown in FIG. 12, where CF ₄ , C ₄ F ₈ , and CHF are filled. ₃ , simulated gas containing CO, COF ₂ , SiF ₄ , HF, F ₂ was passed. The gas processing apparatus shown in FIG. 12 includes a heater at the outer periphery and the center of the column, and is configured to easily raise the temperature inside the firing column to a uniform temperature. The treatment temperature of the PFC decomposition treatment agent layer was controlled at 750 ° C., and the exhaust gas flow rate was 150 L / min.

なお、表中の記号「＜」は、例えば０．２ｐｐｍ未満であることを示す（以下同様）。 Table 3 shows the inlet gas composition and the outlet gas composition after 8 hours of treatment.

The symbol “<” in the table indicates, for example, less than 0.2 ppm (the same applies hereinafter).

From Table 3, PFC, CO, and acidic gas were all processed well below the detection limit at the gas processing apparatus outlet after 8 hours. After processing the gas, an XRD analysis of the PFC decomposition treatment agent (Sample No. 1-3) was performed. From the XRD chart shown in FIG. 16, in addition to the characteristic peak of CaO, an X-ray diffraction peak of CaF ₂ appeared, and it was confirmed that F was fixed to Ca in the PFC decomposition treatment agent.
[Comparative Example 1]

As a comparative example, 94 L of a mixture of Al (OH) ₃ and Ca (OH) ₂ was filled in the gas processing apparatus (large column, diameter 350 mm × height 850 mm) shown in FIG. 12, and N ₂ flow rate: 60 L / min. Was allowed to flow downward and calcined at 300 ° C. for 8 hours, at 500 ° C. for 9 hours, and then at 750 ° C. for 8 hours. Divide the mixture in the large column of FIG. 1-No. After firing, a fixed amount was collected for each layer shown in FIG. 12, the water content was measured by thermal analysis, and the crystalline compound was identified by XRD analysis.
In FIG. An example of an XRD analysis chart for 5 is shown. CaO and Ca (OH) ₂ peaks were observed.

Further, 49 ml of the obtained fired body was filled in a mini column (diameter 22 mm × height 300 mm) of the gas processing system shown in FIG. 13 (however, the mini column was only the first cylinder), and CF ₄ inflow concentration: 1 0.0%, gas flow rate: 410 ml / min, treatment temperature: 750 ° C., and the removal rate after passing gas for 3 hours was determined. The results are shown in Table 4. In the table, sample No. Indicates the position of the collected layer shown in FIG. Sample No. 0 means a mixture of green Al (OH) ₃ and Ca (OH) ₂ .

Table 4 shows the control system firing conditions and water content, XRD analysis results, and CF ₄ removal rate.

From Table 4, it can be seen that there is a difference in moisture content and XRD analysis results depending on the sampling position, and uniform baking is not performed. In particular, the CF ₄ removal rate of the fired bodies collected from the middle layer to the lower layer is very low. This is because moisture generated when firing under a high temperature condition of 750 ° C. or more stays around the mixture to create a high temperature and high humidity condition, a hydrothermal synthesis reaction occurs, promotes crystallization, and decreases activity It is thought that it was made.

Also, were XRD analyzed samples after CF ₄ is removed. As an example, sample No. The XRD analysis chart of No. 5 is shown in FIG. Compared with the XRD analysis chart of FIG. 17, Ca (OH) ₂ disappears, and a peak of CaF ₂ is observed instead.
[Test Example 2]

Using the gas treatment system having the configuration shown in FIG. 13, the treatment performance of the PFC decomposition treatment agent of the present application baked at 750 ° C. for 1.5 hours was examined. Two SUS mini columns (diameter 22 mm x height 300 mm) with a ceramic tube furnace attached to the outer periphery were connected in series, and each mini column was filled with 49 ml of the PFC decomposition treatment agent of the present invention. CF ₄ concentration of inflow at a stable at 750 ° C.: 1.0%, flow rate: started 410 ml / min in a flow-through gas of CF _4. In the performance comparison, the processing time until the CF ₄ removal rate fell below 95% was measured at the outlet of the second cylinder of the mini column, and it was determined that the longer the processing time, the better the performance. Table 5 shows the results of performance comparison using Al (OH) ₃ to Ca (OH) ₂ molar ratio as a variable when Al (OH) ₃ having an average particle size of 120 μm is used.

Table 5 shows the molar ratio of Al (OH) ₃ to Ca (OH) ₂ and the CF ₄ treatment performance.

From Table 5, when the average particle diameter is the same, Al (OH) ₃ : Ca (OH) ₂ molar ratio is in the range of 3: 7 to 5: 5 and shows good processing performance. It can be seen that the processing performance is maximized. Next, using the gas treatment system shown in FIG. 13, under the same treatment conditions, the molar ratio of Al (OH) ₃ : Ca (OH) ₂ was set to 3: 7 and baked at 750 ° C. for 1.5 hours. The relationship between the average particle diameter of Al (OH) ₃ and the CF ₄ treatment performance was examined. At that time, Ca (OH) ₂ having an average particle diameter (median diameter) of 5 μm was used.

Table 6 shows the average particle diameter of Al (OH) ₃ and the CF ₄ treatment performance.

From Table 6, the tendency for processing performance to improve was recognized, so that the average particle diameter of Al (OH) ₃ was large. From the results of the above test examples, the highest CF _{4 in} terms of performance when the molar ratio of Al (OH) ₃ : Ca (OH) ₂ is 3: 7 and the average particle diameter of Al (OH) ₃ is 120 μm. It can be seen that processing performance is obtained. However, if mass production is performed using this composition on an industrial basis, the recovery rate of the powder product is poor and the cost is high. Therefore, commercialization was attempted with the same molar ratio and an average particle size of 90 μm. When the performance was evaluated under the same conditions with this composition, the treatment time when the CF ₄ removal rate was 95% was 34.8 hours, and it was confirmed that there was no significant difference compared to the optimum composition. Furthermore, when Al (OH) ₃ was used without sieving, the average particle size was 55 μm, but it was confirmed that the treatment time when the CF ₄ removal rate was 95% was 31.2 hours. It was. This treatment time is not different from the treatment time of 31.5 hours with an average particle diameter of 60 μm obtained by sieving Al (OH) ₃ . Since the treatment time when the CF ₄ removal rate is 95% is 30 hours or more, it can be practically used. Therefore, considering the balance between production cost (sieving) and performance, Al (OH) ₃ has an average particle diameter of 55 μm. That's all there is to it.

Further, XRD analysis was performed on the PFC decomposition treatment agent after the CF ₄ removal test. An XRD chart is shown in FIG. In addition to the CaO peak, a CaF ₂ peak was observed, indicating that F was fixed to Ca in the PFC decomposition treatment agent.
[Test Example 3]

The PFC decomposition treatment agent of the present application is considered to be a composite oxide of amorphous Al ₂ O ₃ and CaO. For comparison, a simple mixture of commercially available α-type crystalline Al ₂ O ₃ (powder with a particle size of 20 μm) and CaO (powder) in a molar ratio of 3: 7 is compression-molded to prepare a 1 to 4 mm pulverized product. , CF ₄ treatment was performed with the gas treatment system shown in FIG. 13 (however, the mini-column was only the first cylinder). Filling the simple mixture 49ml to mini-column of a gas processing system, stable at by CF ₄ concentration of inflow at 650 ° C.: 1.0%, flow rate: starts passing gas CF ₄ at 410 ml / min, depending on the processing time CF ₄ Change in removal rate was observed. Table 7 shows the CF ₄ removal rate when the PFC decomposition treatment agent of the present invention (Sample No. 1-3 in Table 1) is used and treated at a treatment temperature of 650 ° C.

Table 7 shows a comparison between a fluorine fixing agent (PFC decomposition treatment agent), a simple mixture of α-type crystalline Al ₂ O ₃ and CaO (powder).

As is clear from the results shown in Table 7, the simple mixture of α-Al ₂ O ₃ and CaO is not only less active than the PFC decomposition treatment agent, but also cannot withstand practical use in a short time after the treatment starts. The performance will deteriorate.
[Test Example 4]

100 L of PFC decomposition treatment agent (sample No. 1-3) prepared in [PFC decomposition treatment agent A] was charged into an actual reactor (diameter 350 mm × height 850 mm, equipped with external heater and internal heater), and nitrogen gas 50 L / The temperature was raised to 750 ° C. over 8 hours while pouring min, and field evaluation was performed. The actual exhaust gas treated in the actual reactor is PFC (CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CHF ₃ , CH ₂ F ₂ , NF ₃ ) and acid gases _{(COF 2, SiF 4, F} 2, HF) and _CO, contained CH _4, N 2 O, the _{H 2.} In the field evaluation, an actual exhaust gas flow rate of 150 L / min, purge air of 10 L / min is introduced, the inside of the reaction vessel is controlled to 750 ° C., and the process is terminated when the PFC removal rate reaches 86 to 88%. The measurement was performed by measuring the F adsorption amount of the PFC decomposition treatment agent (fluorine fixing agent) at the end of the treatment. As a control, Al (OH) ₃ and Ca (OH) ₂ were filled in an actual reactor without baking, and nitrogen gas was introduced at 50 L / min for 8 hours at 300 ° C., then at 500 ° C. for 8 hours, and further at 750 The temperature was raised at 8 ° C. over 8 hours, and field evaluation was performed in the same manner.

＊ Ｆ吸着量をすべてＣＦ_４であると仮定して換算した値
＊＊充填量７１ｋｇに換算した値 Table 8 shows the field evaluation in an actual reactor.

* Value converted assuming that all F adsorption amounts are CF ₄ * * Value converted to a charge of 71 kg

Water emerged from the column after treatment of the control mixture.
According to Table 8, the PFC decomposition treatment agent of the present application does not generate moisture during the actual exhaust gas treatment unlike the unfired control mixture, and the F adsorption amount (CF ₄ treatment amount) can be treated about twice as much. You can see that it was made.
[Test Example 5]

The influence of Na on the decomposition action of PFC was investigated.
In order to determine the relationship between the Na content and the CF ₄ treatment performance, the PFC decomposition treatment agent was calcined under the following conditions to prepare treatment agents having different Na contents. Table 9 shows a comparison of treatment capacities with PFC decomposition treatment agents having different Na contents. PFC decomposition treatment agent, average particle diameter 90μm of Al (OH) _3, an average particle size 5μm of Ca (OH) _2, were mixed as a blending ratio of 3: 7 with Al (OH) ₃ and Ca (OH) ₂ The sample was packed in a minicolumn (diameter 22 mm × height 300 mm), mounted in a ceramic tube furnace, and fired at 600 ° C. for 5 hours while supplying N ₂ and 410 mL / min. Each 49 mL of these PFC decomposition treatment agents was filled into a minicolumn of the gas processing system shown in FIG. 13 (however, the minicolumn was only the first cylinder), CF ₄ inflow concentration: 1.0%, gas flow rate: 410 mL / min. Process temperature: After passing gas at 750 ° C. for 3 to 4 hours, heated with nitrogen alone at 410 mL / min and 750 ° C., again CF ₄ inflow concentration: 1.0%, gas flow rate: 410 mL / min, process temperature: The processing time until the CF ₄ removal rate decreased to 95% at 750 ° C. was determined. There was a tendency for the treatment time to become longer as the Na content was smaller, and there was a correlation between the Na content and the CF ₄ treatment performance.

Table 9 shows the relationship between Na content and CF ₄ processing performance.

Since it is preferable that the treatment lifetime is long, the Na content of the fired product is preferably 0.03 wt% or less, more preferably 0.01 wt% or less. In order to obtain such a treatment agent, as raw materials, Al (OH) ₃ containing 0.03 wt% or less, preferably 0.01 wt% or less Na, and 0.03 wt% or less, preferably 0.01 wt% or less. It is preferable to use Ca (OH) ₂ containing Na.
[Test Example 6]

The influence of moisture contained in the exhaust gas was investigated.
In order to obtain the relationship between the amount of water contained in the exhaust gas and the treatment performance of the PFC decomposition treatment agent for CF ₄ , first, the PFC decomposition treatment agent was adjusted under the following conditions. PFC decomposition treatment agent, Al (OH) ₃ having an average particle diameter of 90 [mu] m, Ca (OH) ₂ having an average particle diameter of 5μm, Al (OH) ₃ and Ca (OH) a mixing ratio of a molar ratio of ₂ 3 The mixture was mixed as a pair 7, filled into a minicolumn (diameter 22 mm × height 300 mm), mounted in a ceramic tube furnace, and fired at 600 ° C. for 5 hours while feeding N ₂ and 410 mL / min.

Next, 49 mL of this PFC decomposition treatment agent is packed into a mini-column of the gas treatment system shown in FIG. 21, and CF ₄ inflow concentration: 1420 ppm (CF ₄ 1% diluted to 1420 ppm with N ₂ ), gas flow rate: Gas was passed at 104 mL / min, SV: 127 hr-1, treatment temperature: 750 ° C., and the treatment time until the CF ₄ removal rate decreased to 95% was determined. The gas contained in the gas flow is a gas obtained by adding a predetermined amount of CF ₄ to N ₂ that has been assimilated with water. The amount of moisture to be introduced was adjusted by the heating temperature of the explosion bottle.
Table 10 shows the amount of moisture introduced.

Table 11 shows the treatment performance of the PFC decomposition treatment agent for CF ₄ gas having different moisture contents. It was confirmed that the treatment performance of the PFC decomposition treatment agent was lowered depending on the amount of moisture introduced. Further, it was found that when the water introduction amount was 0.95 mg / min, the processing performance was the same as when no water was added.

Table 11 shows the relationship between the moisture content and the processing performance.

Further, the maximum amount of water contained in the exhaust gas is the amount of saturated water vapor, and the amount of saturated water vapor at 30 ° C. is 30.3 mg / L. Therefore, the exhaust gas discharged from a semiconductor manufacturing apparatus, for example, an ashing apparatus that is highly likely to use H ₂ O, may contain a maximum of 30.3 mg / L of moisture at 30 ° C. This water content is the closest value to the average water content of 3.26 mg / min in Table 11, and it can be seen that the processing time of the PFC decomposition treatment agent is reduced to about 1/4 compared to the case without water addition. .

As a result, when moisture is contained in the exhaust gas, the activity of Al ₂ O ₃ is blocked in the composite oxide of Al ₂ O ₃ and CaO, and the calcium oxide is changed to calcium hydroxide, so that the fluorine component is sufficient. It is thought that it is not processed.
CaO + H ₂ O → Ca (OH) ₂

FIG. 22 is an XRD chart of the PFC decomposition treatment agent after the treatment of CF ₄ gas containing a moisture content of 3.26 mg / min. In addition to CaF ₂ and CaO, Ca (OH) ₂ was identified, and it was confirmed that Ca (OH) ₂ was produced by introduction of H ₂ O.

  FIG. 23 is a graph showing the relationship of Table 11. FIG. 23 shows that the amount of water in the gas to be treated is preferably 1.2 mg / min or less, more preferably 1.0 mg / min or less. In this way, the service life of the PFC decomposition treatment agent can be maintained for about 300 hours or more.

In addition, when the present inventors apply the method described in Patent Document 4 to a scaled-up actual machine, the moisture generated in the apparatus does not evaporate due to heating, resulting in an excess of moisture, and the aluminum oxide is turned into α. (Crystallization) to decrease the activity of aluminum (change in microstructure at the active site, for example, deterioration due to adsorption of OH groups to the active site and local alpha conversion at the active site, It is found that a PFC decomposition treatment agent that maintains high activity of aluminum can be obtained by avoiding crystallization while preventing excessive water during firing, and the PFC decomposition treatment agent ( Al ₂ O ₃ and CaO composite oxide) have been completed. Further, the composite oxide of _Al 2 _{O 3} and CaO, was clarified that it is possible to improve the processing performance of the decomposition agent than a simple mixture of _Al 2 _{O 3} and CaO.

In the gas treatment apparatus according to the embodiment of the present invention using the composite oxide of Al ₂ O ₃ and CaO, the service life of the decomposition treatment agent can be extended, and further, in the exhaust gas at the stage before the PFC decomposition treatment By reducing the amount of water, the service life of the composite oxide of Al ₂ O ₃ and CaO can be further improved. Therefore, it is possible to provide a gas processing apparatus that can reduce the number of times of replacement of the processing agent, improve working efficiency, and reduce running costs, and a semiconductor manufacturing apparatus including this apparatus.

1, 2, 3, 4, 5 Gas treatment device 10 Moisture removal device
10a Mist trap 10b Moisture adsorption device 10c Cooling device 11 Spray 12 Cooling water 13 Moisture adsorbent 14 Heat exchanger 20 PFC treatment device 21, 22, 174 Inner tube 30 Device body 30a, 30b Lid 31 Internal heater 31a First inside Heater 31b 2nd internal heater 32 External heater 32a 1st external heater 32b 2nd external heater 32c 3rd external heater 33 Treatment agent arrangement | positioning part 34 Insulation material 35 Air layer 36, 166, 176 Treatment agent 37 Current plate 38 Gas introduction part 39 Gas exhaust part 40 Gas introduction pipe 50 Exhaust pipe 110 Oxide film etching apparatus 120 Poly silicon etching apparatus 130 Metal etching apparatus
140 Ashing device 150 Vacuum pump 160 First dry-type abatement device 170 Second dry-type abatement device 161, 171, 172, 173 Column 175 Heat transfer fin 200 Mesh members a, b, c Space

Claims (8)

A gas processing apparatus for processing a gas containing PFC (perfluoro compound);
A water removal device for reducing H ₂ O contained in the gas containing PFC;
A PFC treatment apparatus filled with a decomposition treatment agent containing a composite oxide of Al ₂ O ₃ and CaO that introduces a gas containing PFC with reduced H ₂ O in the moisture removal apparatus and decomposes the PFC. Prepare;
Gas processing device. A gas processing apparatus for processing a gas containing PFC and a gas containing acid gas and / or corrosive gas;
A first dry abatement device for removing the acid gas and / or the corrosive gas;
A PFC treatment disposed downstream of the first dry-type abatement apparatus and filled with a decomposition treatment agent containing a composite oxide of Al ₂ O ₃ and CaO that decomposes the PFC in order to remove the PFC Comprising a device;
Gas processing device. A second dry-type detoxifying device that has a heating device and removes the PFC at a temperature higher than that of the first dry-type detoxifying device;
The second dry-type abatement apparatus is disposed downstream of the first dry-type abatement apparatus and upstream of the PFC processing apparatus with respect to the gas flow including the PFC.
The gas processing apparatus according to claim 2. The second dry abatement device was formed integrally with the PFC treatment device;
The gas processing apparatus according to claim 3. A water removal device that reduces H ₂ O contained in the gas containing the PFC downstream of the first dry-type abatement device and upstream of the PFC treatment device;
The gas processing apparatus of any one of Claim 2 thru | or 4. The moisture removing device for reducing H ₂ O is a device having at least one of a mist trap, a moisture adsorbent, and a heat exchanger;
The gas processing apparatus according to claim 1 or 5. The Al ₂ O ₃ and CaO composite oxide has an average particle diameter (median diameter ) of 55 μm or more and 160 μm or less of Al (OH) ₃ and Ca (OH) ₂ in a molar ratio of 3: 7 to 5: 5. A composite oxide obtained by calcining a mixture in the temperature range of 430 ° C. to 890 ° C. in a nitrogen flow or air flow;
The gas processing apparatus according to any one of claims 1 to 6. An etching apparatus for etching a semiconductor substrate;
An ashing device for removing unnecessary resist on the semiconductor substrate etched by the etching device;
The gas processing apparatus according to any one of claims 1 to 7, wherein a gas including PFC discharged from the etching apparatus and / or the ashing apparatus is processed.
Semiconductor manufacturing equipment.

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