Fluorine fixing agent, fluorine fixing method, fluorine recovery method, and method for treating exhaust gas from semiconductor production device

Abstract

To provide a fluorine fixing agent that fixes fluorine from exhaust gas containing HF, F2, SiF4 or the like and a method for producing the same, and a fluorine fixing method and a fluorine recovery method.SOLUTION: A fluorine fixing agent composed of CaO with a specific surface area of 15 m2 / g or more and 35 m2 / g or less is exposed to a fluorine-containing compound at a temperature of 500°C or higher and 600°C or lower. Thus, F is fixed as CaF2. Then, the fluorine fixing agent with the fixed F is sequentially exposed to acid and alkali, thereby recovering the solid CaF2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a fluorine fixing agent, a fluorine recovery method, and a method for treating exhaust gas from semiconductor manufacturing equipment, and in particular to a technology for recovering fluorine from exhaust gas containing fluorine-containing compounds such as HF, F2, and SiF4, which are discharged from processes such as dry cleaning the inner surfaces of semiconductor manufacturing equipment, film formation processes, and etching processes for various films such as oxide films. [Background technology]

[0002] In the semiconductor industry, HF, F2, etc. are used in the cleaning process, etching process, and CVD process of the inside of semiconductor manufacturing equipment, and fluorine-containing compounds including SiF4 are discharged as by-product gases. The exhaust gas containing these fluorine-containing compounds is either reacted and removed with solid chemicals and disposed of as waste, or absorbed in a solution and treated as industrial wastewater. Meanwhile, in recent years, the depletion of fluorite, the raw material for fluorine, has become an issue, and the recovery and reuse of fluorine has become an important issue.

[0003] Examples of methods for treating exhaust gases containing fluorine-containing compounds that have been proposed include a method of decomposing fluorocarbons in exhaust gases using a treating agent containing aluminum oxide and an alkaline earth metal oxide (Patent Document 1); a method of decomposing sulfur fluoride in exhaust gases using a treating agent containing aluminum oxide and an alkaline earth metal oxide (Patent Document 2); a method of decomposing fluorine compounds in exhaust gases using a treating agent containing alumina and an alkaline earth metal compound, and in some cases, oxides of metals such as copper, tin, vanadium, etc. (Patent Document 3); and a method of decomposing PFCs in exhaust gases using a treating agent containing aluminum hydroxide and calcium hydroxide (Patent Document 4).

[0004] However, in the conventional treatment methods described above, especially when treating a gas that is difficult to decompose such as CF4, the treatment temperature is as high as 800 to 1000°C, so that the treatment device quickly deteriorates due to heat and the energy consumption of the device is large. In addition, the conventional treatment agent has a problem that it has a short service life and needs to be replaced frequently. For example, in the methods disclosed in Patent Documents 1 to 3, PFC gas is decomposed by reacting PFC with aluminum oxide (alumina) to generate aluminum fluoride. However, since the reaction activity of aluminum oxide is low, high-temperature reaction conditions are required to efficiently proceed with this reaction. Furthermore, the generated aluminum fluoride forms a layer on the surface of the aluminum oxide, which may poison the aluminum oxide and cause it to lose its catalytic activity in a short time, and in such a case, there is a problem that the treatment agent needs to be replaced frequently.

[0005] PFC gas is reacted with aluminum hydroxide, and the hydrogen in the hydroxyl group of the aluminum hydroxide converts fluorine into hydrogen fluoride. The hydrogen fluoride produced then reacts with calcium hydroxide. A method has been proposed that can efficiently decompose PFC gases and the like at a lower temperature than conventional methods by generating calcium fluoride (Patent Document 4). However, although this method is effective in small-scale equipment, it has been confirmed that when scaled up to practical scale, the activity of aluminum is inhibited and sufficient removal effect may not be achieved.

[0006] The applicant has developed a method for treating an exhaust gas containing a fluorine-containing compound, which comprises filling an alkaline agent containing at least one of Ca(OH)2, Mg(OH)2 or a calcined product thereof on the upstream side of the flow of the exhaust gas, forming a mixture of Al(OH)3 having an average particle size (median size) of 55 μm or more and 160 μm or less and Ca(OH)2 in a molar ratio of 3:7 to 5:5 on the downstream side, drying the mixture, and calcining the mixture in a nitrogen or air flow at a temperature range of more than 430°C and less than 890°C. proposed an exhaust gas treatment method characterized by passing the exhaust gas through a reaction tank filled with a PFC treatment agent (perfluoro compound treatment agent) made of a composite oxide obtained by synthesizing the above-mentioned fluorine (Patent Document 5). However, this method requires a complicated device configuration because different fluorine fixing agents are placed upstream and downstream for treatment. In addition, no method for recovering the fixed F has been proposed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-224565 A [Patent Document 2] JP 2002-370013 A [Patent Document 3] JP 2001-190959 A [Patent Document 4] JP 2005-262128 A [Patent Document 5] JP 2010-158620 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0008] The present invention aims to provide a fluorine-fixing agent that fixes fluorine from exhaust gases containing fluorine-containing compounds, particularly fluorine-containing compounds that are emitted from processes such as dry-cleaning the inner surfaces of semiconductor manufacturing equipment, film-forming processes, and processes for etching various films such as oxide films, and that contain HF, F2, SiF4, etc.; a method for producing the same; and a method for fixing fluorine and a method for recovering fluorine. [Means for solving the problem]

[0009] The present inventors discovered that, unlike commercially available CaO, CaO produced by calcining Ca(OH)2 at 500°C to 600°C has a large specific surface area and can effectively fix F, and that the fixed F can be easily and efficiently recovered by contacting the fluorine fixative with F fixed thereto with an acid and an alkali in turn to dissolve and remove components other than F, which led to the completion of the present invention.

[0010] According to the present invention, the specific surface area is 15 m 2 / g or more 35m 2 The fluorine fixing agent is characterized by comprising CaO having a CaO content of 0.1 to 1.0 ppm by weight per 1000 mg / g or less.

[0011] Also provided is a method for producing the above-mentioned fluorine treatment agent, which comprises calcining Ca(OH)2 at 450°C or higher and 700°C or lower in a nitrogen gas flow.

[0012] Furthermore, there is provided a method for recovering fluorine, which comprises contacting the above-mentioned fluorine fixing agent with a fluorine-containing compound at 500° C. or more and 600° C. or less to fix F as CaF2.

[0013] Also, the fluorine fixing agent is contacted with a fluorine-containing compound at 500°C or more and 600°C or less to fix F as CaF2, contacting the immobilized F with an acid and filtering to recover the solid; The recovered solid is added to a heated alkaline solution to prepare a solution in which SiO2 is dissolved; A method for recovering fluorine is provided, which comprises filtering the solution to recover solid CaF2.

[0014] According to the present invention, a column packed with solid Ca(OH)2 is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO, Next, the flow of nitrogen gas is stopped, and a fluorine-containing gas is flowed at 500° C. or more and 600° C. or less to fix F as CaF2, thereby providing a fluorine fixation method.

[0015] According to the present invention, a column packed with solid Ca(OH)2 is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through it to generate CaO, Next, the flow of nitrogen gas is stopped, and a fluorine-containing gas is circulated at 500°C to 600°C to fix F as CaF2. Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid is added to a heated alkaline solution to prepare a solution in which SiO2 is dissolved; A method for recovering fluorine is provided, which comprises filtering the solution to recover solid CaF2.

[0016] According to the present invention, a column packed with solid Ca(OH)2 is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO, Next, the flow of nitrogen gas is stopped, and a fluorine-containing exhaust gas from the conductor manufacturing equipment is circulated at 500°C or higher and 600°C or lower, thereby fixing F as CaF2.

[0017] Furthermore, according to the present invention, a column packed with solid Ca(OH)2 is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO, Next, the flow of nitrogen gas is stopped, and fluorine-containing exhaust gas from the semiconductor manufacturing equipment is circulated at 500°C to 600°C to fix F as CaF2. Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid is added to a heated alkaline solution to prepare a solution in which SiO2 is dissolved; A method for treating exhaust gas from a semiconductor manufacturing device is provided, which comprises filtering the solution to recover solid CaF2.

[0018] Furthermore, according to the present invention, a fluorine-containing exhaust gas from a semiconductor manufacturing device is passed through a column packed with the above-mentioned fluorine fixing agent at a temperature of 500°C to 600°C to fix F as CaF2, Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid is added to a heated alkaline solution to prepare a solution in which SiO2 is dissolved; There is also provided a method for treating exhaust gas from a semiconductor manufacturing device, which comprises filtering the solution to recover solid CaF2. Effect of the Invention

[0019] The fluorine fixing agent of the present invention, unlike commercially available CaO, has a large specific surface area, can fix F efficiently, and can easily recover the fixed F.

[0020] The fluorine fixing agent of the present invention can be easily produced by calcining Ca(OH)2 at 450°C or higher and 700°C or lower in a nitrogen gas flow.

[0021] The fluorine recovery method of the present invention can contact the fluorine fixing agent with the fluorine-containing compound at a relatively low temperature of 500°C or more and 600°C or less, thereby solving the problems of rapid deterioration of the treatment equipment due to heat and large energy consumption of the equipment.

[0022] The fluorine recovery method of the present invention can easily recover fluorine in a high yield by simply treating a fluorine-fixing agent having fluorine fixed thereto with an acid and an alkali.

[0023] The fluorine recovery method of the present invention can prepare a fluorine fixing agent, fix F, and recover the fixed F using a single column. [Brief description of the drawings]

[0024] [Figure 1] This is an X-ray diffraction spectrum of a fluorine fixing agent obtained by baking Ca(OH)2 at 500°C in a nitrogen atmosphere. [Diagram 2] 1 is an X-ray diffraction spectrum of commercially available CaO. [Diagram 3] 1 is a graph showing the relationship between the treatment temperature of Ca(OH)2 and the HF treatment amount. [Figure 4] 1 is a graph showing the relationship between the treatment temperature of Ca(OH)2 and the amount of SiF4 treated. Preferred Embodiments

[0025] [Fluoride fixing agent] The fluorine fixing agent of the present invention has a specific surface area of ​​15 m 2 / g or more 35m 2 / g or less, preferably 20m 2 / g or more 30m 2 The specific surface area of ​​commercially available CaO is 3 m 2 / g, the fluorine fixing agent of the present invention has an extremely large specific surface area, where the specific surface area is the specific surface area measured by the BET method.

[0026] The fluorine fixing agent of the present invention can be prepared by calcining Ca(OH)2 in a nitrogen atmosphere at 450°C to 700°C, preferably 500°C to 600°C. At 450°C or higher, Ca(OH)2 is dehydrated and many voids can be formed, but at temperatures above 700°C, the performance of the CaO produced begins to decline. Compared to commercially available CaO, which is often made by calcining CaCO3 at 900°C to 1000°C, the calcination temperature is low and carbon dioxide generation can be suppressed.

[0027] Ca(OH)2 produces CaO through the following dehydration reaction. When the firing temperature is between 460°C and 480°C, the temperature rise is gradual and dehydration proceeds within this temperature range. [ka]

[0028] On the other hand, commercially available CaO is made by calcining CaCO3 at 900℃ to 1000℃ and generating CaO through the following reaction. [ka]

[0029] As will be explained in the examples below, Ca(OH)2 is dehydrated at around 470°C to produce CaO, but in the process of water escaping, the entire Ca(OH)2, including the inside, becomes porous CaO (water is removed and voids are created). In addition, in the temperature range of around 500°C, it is assumed that the bond between Ca and O is loose and the degree of crystallinity is not large (high reaction activity).

[0030] On the other hand, when CaCO3 is fired at high temperatures (900℃ to 1000℃), the CO2 degasses and produces CaO; however, it is assumed that the bond between Ca and O is stronger, the crystallization is more advanced (low reaction activity), and the resulting material is a dense crystalline material with a small pore volume.

[0031] [Fluoride fixing method 1] The fluorine fixation method of the present invention is characterized in that the above-mentioned fluorine fixative is packed into a column, exhaust gas containing fluorine-containing compounds is passed through the column, and the column is heated to 500° C. to 600° C. At temperatures below 500° C., the gas treatment amount decreases, and at temperatures above 600° C., the treatment amount remains unchanged.

[0032] When CaO and a fluorine compound are reacted by heating to between 500°C and 600°C, F is fixed as CaF2 as shown in the following formula. [ka]

[0033] [Fluorine recovery method 1] The fluorine recovery method of the present invention is characterized in that the above-mentioned fluorine fixing agent is packed into a column, an exhaust gas containing a fluorine-containing compound is passed through the column, the exhaust gas is heated to 500°C to 600°C to fix F as CaF2, an acid is passed through the column, the effluent water is filtered to recover a solid matter, the recovered solid matter is added to a heated alkaline solution to prepare a solution in which SiO2 is dissolved, and the solution is filtered to recover solid CaF2.

[0034] In the fluorine fixing agent, unreacted CaO is dissolved as soluble CaCl2 by reaction with an acid, preferably hydrochloric acid. [ka]

[0035] The SiO2 remaining as a solid goes into solution as soluble Na2SiO3 upon reaction with an alkali, preferably NaOH solution. [ka]

[0036] CaF2 is insoluble in neither hydrochloric acid nor NaOH solution and can therefore be recovered as a solid.

[0037] The acid and alkali used above may be ordinary industrial chemicals. Although hydrochloric acid has been used in the above description, any acid capable of forming a soluble salt with Ca may be used, and is not limited to hydrochloric acid. For example, nitric acid may be used. Furthermore, although sodium hydroxide has been used as the alkali, any alkali capable of forming a soluble salt with SiO2 may be used, and is not limited to sodium hydroxide. For example, potassium hydroxide may be used.

[0038] The amount of acid added should be at least the equivalent amount at which unreacted CaO dissolves, for example, 1 equivalent to 1.5 equivalents, preferably 1.2 equivalents. The concentration of alkali is 4 wt% to 6 wt%, preferably 5 wt%.

[0039] When passing the alkali, it is preferable to set the temperature to 70°C or higher and 80°C or lower. If the temperature of the alkali is lower than 70°C, the treatment time will be prolonged, which is not preferable. If the temperature exceeds 80°C, the amount of water evaporation will increase, and the scattering of NaOH as mist will increase, which is not preferable, as it increases the risk of exposure to high-concentration NaOH.

[0040] The filtration of the effluent obtained by passing the acid through and the filtration of the solution after the alkali treatment can be carried out using a chemical-resistant filter with a pore size of 0.45 μm to 1.0 μm, preferably about 0.6 μm. If the pore size is too small, it will clog, and if it is too large, fine particles of CaF2 will pass through the filter, reducing the recovery rate, which is not preferable.

[0041] [Fluoride fixing method 2] The present invention also provides a fluorine fixation method, which comprises heating a column packed with solid Ca(OH)2 to 450°C or more and 700°C or less while passing nitrogen gas through the column to generate CaO, and then stopping the flow of nitrogen gas and passing a fluorine-containing gas at 500°C or more and 600°C or less to fix F as CaF2. This method does not require a separate preparation of a fluorine fixation agent, and instead allows the steps from preparation of the fluorine fixation agent to fixation of fluorine to be carried out using a single column.

[0042] [Fluorine recovery method 2] The present invention also provides a method for treating exhaust gas from a semiconductor manufacturing equipment, which comprises heating a column packed with solid Ca(OH)2 to 450°C to 700°C while passing nitrogen gas through the column to generate CaO, stopping the flow of nitrogen gas and passing fluorine-containing exhaust gas from a semiconductor manufacturing equipment through the column at 500°C to 600°C to fix F as CaF2, filtering the effluent water obtained by passing an acid through the column to recover solid matter, adding the recovered solid matter to a heated alkaline solution to prepare a solution in which SiO2 is dissolved, filtering the solution to recover solid CaF2. This method does not require a separate preparation of a fluorine fixing agent, and can be carried out from the preparation of the fluorine fixing agent to the fixation and recovery of fluorine using a single column. EXAMPLES

[0043] [Example 1] A quartz mini-column (hollow cylinder of 24 mmφ×500 mmh) was filled with 80 ml (53.71 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), which was then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C while supplying N2 gas at 410 sccm, and maintained at 500°C for 2 hours. XRD analysis (X-ray diffraction method) of the product after firing was performed, and the product was identified from the X-ray diffraction peak. The results are shown in Figure 1. For comparison, XRD analysis of commercially available CaO (manufactured by Yazaki Industries: crushed product of 1 mm to 3 mm) was performed, and the product was identified from the X-ray diffraction peak. The results are shown in Figure 2. It was confirmed that both were CaO.

[0044] [Example 2] A quartz mini-column (hollow cylinder of 24 mmφ×500 mmh) was filled with 80 ml (53.71 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C or 600°C while supplying N2 gas at 410 sccm, and maintained at 500°C or 600°C for 2 hours. The specific surface area of ​​the product after firing was measured by the BET method. For comparison, the specific surface area of ​​commercially available CaO (manufactured by Yazaki Industries: crushed product of 1 mm to 3 mm) was also measured. The results are shown in Table 1. There was no significant difference in the specific surface area between the firing temperatures of 500°C and 600°C, but it was confirmed that the specific surface area was significantly larger than that of commercially available CaO.

[0045] [Table 1]

[0046] [Example 3] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 49 ml (32.9 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The internal temperature was raised to room temperature, 200°C, 300°C, 400°C, 500°C, 550°C, and 600°C while supplying N2 gas at 410 sccm. After maintaining each temperature for 2 hours, the supply of N2 gas was stopped, and a gas containing 4.0 vol% HF was supplied for 502 hours. -1 The time until 1 ppm of HF was detected at each temperature was measured, and the HF treatment amount was calculated from the amount of HF-containing gas passed through to investigate the temperature dependency of the HF treatment of Ca(OH)2. The results are shown in Table 2 and Figure 3. It was confirmed that the HF treatment amount increased gradually up to 300°C, increased sharply between 300°C and 500°C, and became almost constant above 500°C.

[0047] [Table 2]

[0048] [Example 4] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 43 ml (28.87 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to internal temperatures of 150°C, 300°C, 400°C, 500°C, and 600°C while supplying N2 gas at 400 sccm. After maintaining each temperature for 2 hours, the supply of N2 gas was stopped and a gas containing 0.5 vol% SiF4 was supplied for 558 hours. -1 The time until 1 ppm of SiF4 was detected at each temperature was measured, and the amount of SiF4 processed was calculated from the amount of gas containing SiF4 passed through, and the temperature dependency of the SiF4 processing of Ca(OH)2 was investigated. The results are shown in Table 3 and Figure 4. It was confirmed that the amount of SiF4 processed increased gradually up to 500°C, and then increased rapidly at temperatures above 500°C to 600°C.

[0049] [Table 3]

[0050] [Example 5] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 49 ml (32.9 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C while supplying N2 gas at 410 sccm. After maintaining the temperature at 500°C for 2 hours, the supply of N2 gas was stopped and a gas containing 1.0 vol% SiF4 was supplied for 502 hours. -1 The time until 1 ppm of SiF4 was detected was measured, and the amount of SiF4 treated was calculated from the amount of gas containing SiF4 passed through. For comparison, a commercially available CaO (Yazaki Kogyo Co., Ltd.: 1 mm The SiF4 processing amount was determined under the same conditions, except that crushed CaO (~3 mm) was filled. The results are shown in Table 4. According to the method of the present invention, it was possible to process 8 times as much as the process using commercially available CaO.

[0051] [Table 4]

[0052] [Example 6] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 38 ml (25.51 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C while supplying N2 gas at 300 sccm. After maintaining the temperature at 500°C for 2 hours, the supply of N2 gas was stopped and a gas containing 2.5 vol% F2 was supplied for 480 hours. -1 The time until 1 ppm of F2 was detected was measured, and the F2 processing amount was calculated from the amount of gas containing F2 passed through. For comparison, the F2 processing amount was measured under the same conditions except that commercially available CaO (manufactured by Yazaki Industries: crushed product of 1 mm to 3 mm) was filled instead of Ca(OH)2. The results are shown in Table 5. According to the method of the present invention, it was possible to process 2.5 times as much as the process using commercially available CaO.

[0053] [Table 5]

[0054] [Example 7] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 38 ml (25.51 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C while supplying N2 gas at 300 sccm. After maintaining the temperature at 500°C for 2 hours, the supply of N2 gas was stopped and a gas containing 2.5 vol% F2 and 3.2 vol% HF was supplied for 480 hours. -1 The amount of F2 and HF processed was measured by measuring the time until F2 leaked at 1 ppm or more, and the amount of F2 and HF processed was calculated from the amount of gas containing F2 and HF passed through. For comparison, the amount of F2 and HF processed was measured under the same conditions except that commercially available CaO (manufactured by Yazaki Industries: crushed product of 1 mm to 3 mm) was filled instead of Ca(OH)2. The results are shown in Table 6. According to the method of the present invention, it was possible to process 1.8 times as much as the process using commercially available CaO.

[0055] [Table 6]

[0056] [Example 8] A quartz mini-column (24 mmφ×500 mmh hollow cylinder) was filled with 100 ml (67.14 g) of Ca(OH)2 (manufactured by Yazaki Industries: cylindrical particles with a diameter of 1.6 mm and a length of 3.2 mm to 6.4 mm), and then loaded into a ceramic tubular furnace. The furnace was heated to an internal temperature of 500°C while supplying N2 gas at 410 sccm. After maintaining the temperature at 500°C for 2 hours, the supply of N2 gas was stopped and the actual exhaust gas from etching with HF and F2 from a semiconductor manufacturing equipment was collected and stored for 246 hours. -1The gas was allowed to flow for 20 hours at 100°C. After treatment, the solid matter was removed from the column and analyzed by XRF (X-ray fluorescence), revealing the following composition: CaF2: 58wt%, CaO: 30wt%, SiO2: 12wt%. It was confirmed that F was fixed to the fluorine fixing agent from the fluorine-containing compounds in the actual exhaust gas.

[0057] The solid was immersed for 1 hour in a hydrochloric acid solution containing 1.2 times the amount of residual CaO, and the solid was then contacted with hydrochloric acid, after which it was filtered through a glass fiber filter with a pore size of 0.6 μm. The solid matter remaining on the glass fiber filter was immersed for 30 minutes in a 5% NaOH solution heated to 70°C, and then filtered through a glass fiber filter with a pore size of 0.6 μm. The solid matter remaining on the glass fiber filter was analyzed by XRF, and found to be CaF2: 49.8 wt%, SiO2: 0.2 wt%. It was confirmed that F was recovered from fluorine-containing compounds in the actual exhaust gas by fixing it to the fluorine fixing agent. [Industrial Applicability]

[0058] According to the present invention, F can be fixed as CaF2 in a fluorine fixing agent and recovered from a fluorine compound-containing gas at a lower temperature and in a simpler manner than the conventional treatment method. This is useful as a treatment method for a fluorine compound-containing gas discharged from a semiconductor manufacturing device.

Claims

1. Specific surface area is 15m ２ / g or more 35m ２ Fluorine fixing agent characterized by comprising CaO having a CaO content of 0.1g or less.

2. Ca(OH) ２ 2. The method for producing a fluorine fixing agent according to claim 1, wherein the above is calcined at 450° C. or higher and 700° C. or lower in a nitrogen gas flow.

3. The fluorine fixing agent according to claim 1 is brought into contact with a fluorine-containing compound at 500°C or higher and 600°C or lower, and F is converted into CaF ２ Fluorine fixation method, characterized by fixing fluorine as follows.

4. The fluorine fixing agent according to claim 1 is brought into contact with a fluorine-containing compound at 500°C or higher and 600°C or lower, and F is converted into CaF ２ and fixed as contacting the F in a fixed state with an acid and filtering to recover a solid; The recovered solid material is added to a heated alkaline solution to form SiO ２ A solution of The solution was filtered to obtain solid CaF ２ Fluorine recovery method, characterized by recovering

5. solid Ca(OH) ２ A column packed with the above is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO. Next, the flow of nitrogen gas is stopped, and a fluorine-containing gas is circulated at 500°C or higher and 600°C or lower to convert F into CaF ２ Fluorine fixation method, characterized by fixing fluorine as follows.

6. solid Ca(OH) ２ A column packed with the above is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO. Next, the flow of nitrogen gas is stopped, and a fluorine-containing gas is circulated at 500°C or higher and 600°C or lower to convert F into CaF ２ and fix it as Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid material is added to a heated alkaline solution to form SiO ２ A solution of Prepare The solution was filtered to obtain solid CaF ２ Fluorine recovery method, characterized by recovering

7. solid Ca(OH) ２ A column packed with the above is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO. Next, the flow of nitrogen gas was stopped, and fluorine-containing exhaust gas from the semiconductor manufacturing equipment was circulated at 500°C or higher and 600°C or lower to convert F into CaF ２ 1. A method for treating exhaust gas from semiconductor manufacturing equipment, comprising: fixing the gas as a gas containing fluorine-containing compound.

8. solid Ca(OH) ２ A column packed with the above is heated to 450°C or higher and 700°C or lower while passing nitrogen gas through the column to generate CaO. Next, the flow of nitrogen gas was stopped, and fluorine-containing exhaust gas from the semiconductor manufacturing equipment was circulated at 500°C or higher and 600°C or lower to convert F into CaF ２ and fix it as Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid material is added to a heated alkaline solution to form SiO ２ A solution of The solution was filtered to obtain solid CaF ２ 1. A method for treating exhaust gas from semiconductor manufacturing equipment, comprising recovering:

9. A fluorine-containing exhaust gas from a semiconductor manufacturing device is passed through a column packed with the fluorine fixing agent according to claim 1 at a temperature of 500°C to 600°C, and F is converted into CaF ２ and fix it as Furthermore, the effluent obtained by passing the acid through the column is filtered to recover solids; The recovered solid material is added to a heated alkaline solution to form SiO ２ A solution of The solution was filtered to obtain solid CaF ２ 1. A method for treating exhaust gas from semiconductor manufacturing equipment, comprising recovering:

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