JP4583880B2 - Exhaust gas treatment method and treatment apparatus - Google Patents

Description

  The present invention relates to an exhaust gas treatment method and an apparatus used therefor, and more particularly, to an effective method and apparatus for detoxifying exhaust gas used in a manufacturing process or a film forming process of a semiconductor or liquid crystal display module.

Conventionally, examples of gases used in a film forming process of a semiconductor or liquid crystal display module include silane (SiH ₄ ) and ammonia (NH ₃ ) for film formation, and a fluorine-based gas for cleaning. A film forming gas such as silane or ammonia (also referred to as a combustible gas) is, for example, plasma-discharged in a chamber to form a Si film or SiN film on the substrate, and fluorine such as NF ₃ for cleaning. The system gas (also referred to as a combustion-supporting gas) can release Si remaining in the chamber out of the system as SiF ₄ .

As shown in FIG. 6, conventionally, the exhaust gas containing the film forming gas and the cleaning gas (film forming exhaust gas) is provided by a combustion type abatement means and a cleaning type dust collecting means provided at the subsequent stage of the film forming apparatus. It is processed in order. A means for removing SiF ₄ from the cleaning exhaust gas is often provided immediately before the combustion type abatement means and immediately after the vacuum box provided with a vacuum pump. SiF ₄ removal means is provided in the vicinity of the gas outlet from the vacuum pump, and hydrate the exhaust gas, and solidifying SiF ₄ Si, F, as is produced from _{NH 3 (NH 4) 2 SiF} 6, By performing solid-liquid separation, SiF ₄ is excluded from the exhaust gas system. In the exhaust gas combustion type abatement means, the combustible gas or the combustion support gas is oxidized by combustion to cause chemical reactions as shown in the formulas (1) to (3), respectively.
SiH ₄ + 2O ₂ → SiO ₂ + 2H ₂ O (1)
4NH ₃ + 7O ₂ → 4NO ₂ + 6H ₂ O (2)
2NF ₃ + 2O ₂ → 2NO ₂ + 3F ₂ (3)
Furthermore, in the cleaning type dust collecting means, the combustion gas is collected while neutralizing and cleaning with alkali-added water to collect SiO _{2 and} to collect acidic components (NO ₂ and F ₂ ) as waste liquid. It comes to separate.

However, conventionally, the product obtained by the reaction of Si, F, and NH ₃ unintentionally precipitates in the piping that leads to the abatement means downstream of the vacuum pump, particularly the downstream of the vacuum pump. There was a problem of blocking. In addition to the SiO ₂ collecting means and the subsequent pipes, precipitates were generated in the cleaning dust collecting means and the subsequent pipes, causing clogging of the pipes and clogging in the cleaning apparatus. For this reason, cleaning of the cleaning type dust collecting means and pipe cleaning are frequently required. Further, since these precipitates cannot be cleaned unless they are hydrofluoric acid, it is necessary to pay attention to safety. Furthermore, there has been a problem that the operation rate of the process is reduced due to such maintenance work as cleaning. In order to solve this problem, the applicant of the present application is a technology for newly providing a dust removal process for removing Si-containing dust discharged from the combustion type abatement process, and combustion type abatement of exhaust gas at a temperature at which precipitates do not precipitate. A technology to be introduced into the process has been developed and a patent application has been filed separately (see Patent Document 1).
Japanese Patent Laid-Open No. 2003-21315

  However, when the exhaust gas is heated to prevent precipitation, the fluorine radicals or fluorine ions react with the highly reactive components of the fluorination reaction present in the system at a certain temperature or higher. Since this is an exothermic reaction, the piping may become hotter than the set temperature of the heater, and the alarm device may be activated. For example, since the sublimation temperature of ammonium silicofluoride is 137 ° C., in consideration of heat transfer and heat dissipation, when the heater set temperature is set to 185 ° C., the high temperature alarm device set to 210 ° C. may operate. In addition, in the piping of the heating section after the occurrence of high temperature, fluorides from the reaction with the piping material components are attached, and there is a large amount of adhesion at higher temperatures, erosion of the piping itself is also seen, There is concern about the thinning of the wall. Therefore, the purpose of the present invention is to achieve the original purpose of preventing clogging due to deposit adhesion when introducing a film-forming exhaust gas into an exhaust gas treatment device, and preventing the piping from becoming unnecessarily hot, and It is another object of the present invention to provide an exhaust gas treatment method and an exhaust gas treatment device capable of preventing the pipe from being thinned and preventing the pipe from being blocked by the precipitation of fluoride due to the reaction with the pipe material.

  In order to achieve the above object, an exhaust gas treatment method of the present invention is a method for treating a film-forming exhaust gas containing a Si component, wherein the exhaust gas is introduced into an exhaust gas treatment process through a pipe by a vacuum pump, and the pipe A check valve is provided in the middle of the pipe, and at least during the exhaust gas treatment step from the vacuum pump in the pipe, the temperature is maintained by the heating means at a temperature at which precipitates do not precipitate from the exhaust gas, The setting temperature of the heating means is in the range of 130 to 180 ° C.

  The exhaust gas treatment apparatus of the present invention is a film-formation exhaust gas treatment apparatus containing a Si component, and is a heating means, an exhaust gas treatment means, and a vacuum pump for introducing the exhaust gas into the exhaust gas treatment means. The vacuum pump and the exhaust gas treatment means are connected by a pipe provided with a check valve in the middle thereof, and in the pipe, at least the space between the vacuum pump and the exhaust gas treatment means is the heating means. Thus, the temperature is maintained at a temperature at which no precipitate is deposited from the exhaust gas, and the set temperature of the heating means is in the range of 130 to 180 ° C.

  The present inventors have made a series of studies in order to solve the above problems. As a result, in the pipe (pipe) from the vacuum pump to the exhaust gas treatment step (means), if the heating means is set at a temperature in the range of 130 to 180 ° C., the original prevention of clogging due to deposit adhesion is achieved. In order to complete the present invention, the object of the present invention can be achieved, and the pipe can be prevented from becoming clogged due to fluoride precipitation due to the reaction with the pipe material and the thinning of the pipe due to the generation of corrosive substances. It came.

  As will be described later, in the exhaust gas treatment method and apparatus of the present invention, if at least the valve body of the check valve is made of a fluororesin, the set temperature of the heating means is changed from 130 ° C to 180 ° C, It can be 130-190 degreeC.

  In the exhaust gas treatment method of the present invention, it is preferable that the heating means is a heater provided in the pipe. Although the structure of the heater provided in the said pipe | tube is not restrict | limited in particular, For example, the structure etc. which wound the electric heater spirally around the said pipe | tube, and covered it with the heat insulating material etc. are mentioned. Examples of the electric heater include a sheath heater and a tape heater. In addition, the structure of the heater provided in the tube is a jacket system (mantle or pipe-shaped heater and heat insulating material matched to the shape of the tube are integrated in a layered manner, and the joint is removed with a fastener, clip, etc. If the configuration is simplified, construction and maintenance can be further improved. Further, the heating means may be means for introducing hot gas into the pipe. An example of the hot gas is a heated nitrogen gas. By using the hot gas, the corrosion gas is diluted, thereby further preventing the corrosion of the pipe. In addition, since exhaust gas can be heated from the inside of the pipe, the fluorination reaction of the inner wall surface can be suppressed without heating the inner wall surface of the pipe more than necessary, which also prevents the pipe from corroding. , Can prevent the thinning of the tube. Thus, introducing an inert hot gas is effective in reducing the reactivity.

In the exhaust gas treatment method of the present invention, it is preferable that a filter that absorbs at least one of fluorine radicals and fluorine ions is provided before the vacuum pump to absorb and remove at least one of fluorine radicals and fluorine ions in the exhaust gas. This is because fluorine radicals and fluorine ions contained in the cleaning gas react with metal ions in the piping material to remove the fluorine components from the production of fluorides such as FeF ₂ , CrF ₂ , and NiF _2. This is to prevent it. Thereby, it becomes possible to prevent the pipe from being thinned and to prevent the pipe from being blocked due to the precipitation of fluoride due to the reaction with the pipe material. As the absorption filter, for example, a honeycomb filter formed of a Si compound or the like is vapor-deposited or impregnated with a calcium compound is effective. In this filter, the calcium compound in the filter reacts with at least one of the fluorine radicals and fluorine ions in the exhaust gas, so that it can be prevented from flowing downstream or the amount flowing downstream can be reduced. It is possible to prevent adverse effects on the downstream piping. In consideration of filter replacement after the reaction, it is also effective to make two systems and easily perform filter replacement by switching pipes.

  In the exhaust gas treatment method of the present invention, it is preferable that at least the valve body of the check valve is made of a fluororesin. By using the fluororesin, the fluorination reaction of the check valve material can be suppressed, the temperature rise can be reduced, and the deterioration thereof can be prevented. Therefore, even if the set temperature of the heating means is, for example, 190 ° C., an abnormally high temperature can be prevented, and precipitation of fluoride due to thinning of the tube and reaction with the tube material can also be prevented. Therefore, the set temperature of the heating means when at least the valve body of the check valve is made of fluororesin is in the range of 130 to 190 ° C. The fluororesin is not particularly limited, and examples thereof include polytetrafluoroethylene (PTFE). Although not particularly limited, a ball check valve may be used as the check valve. The entire valve may be made of a fluororesin.

  In the exhaust gas treatment method of the present invention, it is preferable to measure the temperature and pressure of the pipe. For example, by measuring at least one of the maximum temperature before the check valve and the minimum temperature immediately after the vacuum pump at least one of the inside and the outer surface of the tube, the temperature rise can be grasped before the operation of the high temperature alarm device. You will be able to take measures as soon as possible. Further, the correlation between the occurrence of the temperature rise and the type and pressure of the exhaust gas can be grasped, and the cause of the temperature rise can be easily clarified. For example, the operating state of the valve can be grasped by measuring the pressure in the pipe before and after the check valve.

  The exhaust gas treatment method of the present invention preferably includes a dust removal step for removing Si-containing dust from the exhaust gas generated by the exhaust gas treatment step, and a cleaning step for aqueous cleaning of the dust exhaust gas. In the dust removing step, it is preferable to use a bag filter as dust removing means. In the dust removal process of the bag filter, it is preferable that a compressed gas is supplied to the filter and, at the same time, a gas flow directed from the vicinity of the filter surface to the dust discharge side is applied to the outside of the filter. The dust removal process includes at least m (m is an integer of 3 or more) dust removal means, and each dust removal means implements a dust removal process with at least one dust removal means. It is preferable to switch and use so that the dust collecting process is performed with (m-1) dust removing means. It is preferable that the gas removed in the dust removal step is discharged with an air volume corresponding to the discharge pressure of the gas.

  In the exhaust gas treatment method of the present invention, it is preferable to use pure water to water having a hardness of 0 as water introduced for washing in the washing step. If such water is used, precipitation of Si-containing precipitates can be prevented in subsequent steps.

  In the exhaust gas treatment apparatus of the present invention, it is preferable that the heating means is a heater provided in the pipe. The configuration of the heater provided in the tube is as described above. Further, the heating means may be means for introducing hot gas into the pipe. An example of the hot gas is a heated nitrogen gas. By using the hot gas, the corrosion gas is diluted, thereby further preventing the corrosion of the pipe. In addition, because exhaust gas can be heated from inside the pipe, the fluorination reaction on the inner wall surface can be suppressed without heating the inner wall surface of the pipe more than necessary, which also prevents the pipe from corroding. , Can prevent the thinning of the tube. Thus, introducing an inert hot gas is effective in reducing the reactivity.

  In the exhaust gas treatment apparatus of the present invention, for the same reason as described above, it has a filter that absorbs at least one of fluorine radicals and fluorine ions before the vacuum pump, and at least one of fluorine radicals and fluorine ions in the exhaust gas. Is preferably absorbed and removed.

  In the exhaust gas treatment apparatus of the present invention, for the same reason as described above, it is preferable that at least the valve body of the check valve is made of a fluororesin. Moreover, the preset temperature of the heating means in this case is in the range of 130 to 190 ° C.

  In the exhaust gas treatment apparatus of the present invention, it is preferable to have a measuring means for measuring the temperature and pressure of the pipe for the same reason as described above.

  The exhaust gas treatment apparatus of the present invention preferably includes dust removal means for removing Si-containing dust from the exhaust gas generated by the exhaust gas treatment means, and cleaning means for aqueous cleaning of the dust exhaust gas. The dust removing means is preferably a bag filter. The bag filter further includes dust removal means, and as the dust removal means, the compressed gas is supplied to the filter, and at the same time, the gas flow directed from the vicinity of the filter surface to the dust discharge side to the outside of the filter. It is preferable to provide a gas introduction means for imparting. The dust removing means includes at least m (m is an integer of 3 or more) dust removing means, and each dust removing means performs a dust removal process with at least one dust removing means, and at most (m -1) It is preferable to be provided so as to be switchable so that the dust collecting process is performed by the dust removing means of the table. It is preferable to provide exhaust means capable of changing the air volume according to the pressure of the gas discharged from the dust removing means.

  In the exhaust gas treatment apparatus of the present invention, for the same reason as described above, it is preferable to use pure water to water having a hardness of 0 as the water introduced for cleaning by the cleaning means.

  Next, the present invention will be described in more detail. The exhaust gas treatment method and apparatus of the present invention can be applied to Si component-containing film-forming exhaust gas. Usually, such exhaust gas is generated in a manufacturing process or apparatus of a semiconductor or liquid crystal module, particularly in a film forming process or apparatus, and the method and apparatus of the present invention is applied to such a process or apparatus. Is preferred. In particular, also in the film forming process, it is preferably applied to a gas phase deposition process such as CVD or plasma CVD or exhaust gas generated in an apparatus.

  In the exhaust gas treatment method and apparatus of the present invention, when introducing exhaust gas into the exhaust gas treatment step (means), the exhaust gas is heated so that precipitates do not precipitate. The point is to set the temperature within a range of ˜180 ° C. (when at least the valve body of the check valve is made of fluororesin, a range of 130 ° C. to 190 ° C.). A preferable range of this set temperature is, for example, a range of 165 to 180 ° C. (when at least the valve body of the check valve is made of a fluororesin) when the heating means is a heater provided in the pipe. When the heating means is means for introducing hot gas into the pipe, the temperature is, for example, 130 to 165 ° C. More optimal conditions can be found by further narrowing down the amount of hot gas introduced (dilution ratio) and the hot gas temperature introduced (temperature difference from the exhaust gas). Examples of the present invention will be described below, but the present invention is not limited to these examples.

An example (Example 1) of the present invention will be described with reference to FIG. As shown in FIG. 1, in this apparatus, an exhaust gas treatment means 105, a vacuum pump (V / P) 102 for introducing exhaust gas into the exhaust gas treatment means 105, a pipe 103 connecting the both, and the pipe are heated. The heater 109 is a main component. A check valve 104 is arranged in the middle of the pipe 103, and a heater 109 can heat the space between the vacuum pump 102 and the exhaust gas treatment means 105. As described above, although not particularly limited, a ball check valve may be used as the check valve 104. As described above, the configuration of the heater 109 that heats the tube includes, for example, a configuration in which an electric heater is spirally wound around the tube and covered with a heat insulating material. As described above, the structure of the heater 109 for heating the tube is changed to a jacket system (mantle or pipe-shaped heater and heat insulating material adapted to the shape of the tube are integrated in a layered manner, If the structure is made easy to attach and detach with fasteners, clips, etc., construction and maintenance can be further improved. The vacuum pump 102, the tube 103, the heater 109, and the check valve 104 described above are accommodated in the vacuum box 101. A film forming apparatus (process chamber (P / C)) 107 is connected to the vacuum pump 102 by a pipe. In the figure, an arrow 106 indicates a gas such as a cleaning gas or a film forming gas. Although not shown in the figure, this apparatus is provided with a high temperature alarm device, and is set to 210 ° C., for example. In this apparatus, the cleaning gas or the like introduced into the film forming apparatus 107 is introduced into the vacuum pump 102 as exhaust gas after passing through a predetermined process. The exhaust gas when introduced into the vacuum pump 102 is preferably at room temperature, but may be heated so as to maintain a temperature at which precipitates do not precipitate (for example, 150 ° C. or higher). And it introduce | transduces into the waste gas processing means 105 through the pipe | tube 103 with the vacuum pump 102, and is processed here. At this time, the heater 109 is heated to a certain temperature so that precipitates do not precipitate in the exhaust gas, but the set temperature of the heater 109 at this time is in the range of 165 to 180 ° C. At this temperature, at least in the pipe 103 between the vacuum pump 102 and the exhaust gas treatment means 105, precipitates do not precipitate, and the pipe becomes hot and prevents the high temperature alarm device from operating. it can. The predicted deposit varies depending on the exhaust gas component and the cleaning gas, but is typically a fluorosilicic compound in the case of a Si component-containing film-forming exhaust gas that is generated in the formation of the Si film. In particular, when silane or ammonia is used as the combustible gas and a fluorine-based gas such as NF ₃ is used as the combustion support gas, ammonium silicofluoride ((NH ₄ ) ₂ SiF ₆ ) is predicted. Since the precipitation (sublimation) temperature of ammonium silicofluoride is 137 ° C., the precipitation of the present compound is avoided by maintaining the inside of the tube 103 at a temperature exceeding this. In this case, if the set temperature of the heater is 165 to 180 ° C., the temperature in the tube 103 can be 130 to 160 ° C., precipitation of precipitates can be prevented, and an abnormally high temperature can be prevented. Furthermore, by making at least the valve body of the check valve in the system made of fluororesin, the fluorination reaction of the check valve can be suppressed, and even if the heater set temperature is 165 to 190 ° C., it reaches an abnormally high temperature. The object of the present invention can be achieved. Although not shown, the tube 103 is preferably covered with a heat insulating material. Further, the exhaust gas treatment means includes a combustion type abatement means such as an oxidative combustion apparatus described later. The reaction of the present compound occurs in Si, F, NH ₃ or the like, and one of the precipitate prevention factors is how the reactive gas can be sent without stagnation even at a sublimation temperature or lower.

  Next, another example (Example 2) of the present invention will be described with reference to FIG. As shown in the figure, this apparatus has the same configuration as that of Example 1 except that it has an absorption filter 108 that absorbs at least one of fluorine radicals and fluorine ions and hot gas introduction means 110, and is the same as in FIG. Are given the same reference numerals. As illustrated, the absorption filter 108 is disposed in a tube between the film forming apparatus 107 and the vacuum pump 102. Further, the hot gas introducing means 110 is disposed in the vicinity of the connection portion between the tube 103 and the vacuum pump 102. The absorption filter 108 makes it possible to absorb and remove fluorine radicals and fluorine ions in the exhaust gas, thereby preventing the reaction between the fluorine radicals and fluorine ions and the metal ions of the tube material. As a result, the production of corrosive substances can be prevented. Further, the hot gas introducing means 110 can directly heat the inside of the tube 103, and the heating efficiency is improved. As described above, the hot gas is preferably a heated nitrogen gas, and the temperature is, for example, 130 to 165 ° C. In this apparatus, the exhaust gas treatment process other than the removal of fluorine radicals and fluorine ions and the heating with hot gas is the same as that of the apparatus of the first embodiment.

  Next, an example (Example 3) of the apparatus of the present invention provided with dust removing means and cleaning means will be described with reference to FIG. The exhaust gas treatment device 2 includes an exhaust gas treatment means 4, a dust removal means 14, and a cleaning means 44. Moreover, although not shown in figure, this apparatus is equipped with the vacuum pump and pipe | tube which send waste gas to the waste gas treatment means 4, and this pipe | tube has a non-return valve. And the pipe | tube part between a vacuum pump and waste gas treatment means is heated with the heater so that precipitate may not precipitate in waste gas, and the preset temperature of the heater is the range of 165-180 ° C (the above-mentioned check). When at least the valve body of the valve is made of a fluororesin, the temperature is in the range of 165 to 190 ° C., and so on. In FIG. 3, a manufacturing apparatus for a thin film or the like on which the present processing apparatus is mounted or disposed is additionally described. In this example, a plasma CVD film forming apparatus is particularly used.

As the exhaust gas treatment means 4, for example, a combustion-type abatement means such as a conventionally known oxidation combustion apparatus can be used. In this case, oxygen is supplied from the outside as a combustion gas, and a flame is supplied by a burner or the like to burn and oxidize exhaust gas components with high heat. In the processing means 4, as described above, exhaust gases of various combustible gases (silane, ammonia, phosphine, etc.) and combustion-supporting gases (nitrogen trifluoride, etc.) are SiO ₂ (silica), NO, respectively. _This produces oxides of corresponding elements such as ₂ and water or fluorine. Therefore, the combustion exhaust gas contains these various combustion exhaust gases in addition to the SiO ₂ particles.

  The exhaust gas discharged from the exhaust gas treatment means 4 is introduced into the dust removal means 14. As the dust removing means 14, various conventionally known dust removing devices can be used. For example, a centrifuge, a scrubber, a bag filter or the like can be used, and a bag filter is preferable. This is because the bag filter has a particularly high dust removing effect on fine particles of about 0.1 to 1 μm.

  There are various conventional bug filters. Usually, there are various forms such as mechanical vibration method, back-flow cleaning method, ultrasonic cleaning method, reverse jet method, pulse air method, etc. depending on the mechanism of dust removal from the filter, and it is required as necessary Can be adopted. Preferably, it is a pulse air type bag filter.

  FIG. 4 shows one preferred form of bag filter for use in the present invention. Usually, the pulse air type bag filter includes a housing 16 that holds the filter 18, a top plenum 20 that is partitioned and provided in the upper part of the housing, and a dust collecting part 30 that is provided in the lower part of the housing. Further, the dust removing means 14 of the present invention includes a gas introducing means 40.

  An appropriate number of filters 18 are held in the housing 16, and the filter 18 is usually formed in a cylindrical shape such as a cylindrical shape. The inside of the filter 18 communicates with the inside of the top plenum 20 through the tube sheet 21. The holding portion of the housing 16 for holding the filter 18 is provided with an introduction portion into which exhaust gas to be treated is introduced from the outside. The introduction part 19 is opened when exhaust gas is introduced, but is closed when dust is removed.

  The top plenum 20 is provided via a housing 16 and a tube sheet 21, and communicates with the inside of the filter 18 so that cleaning gas is introduced through the filter 18. Compressed gas can be introduced inside. That is, a discharge unit 22 that discharges the cleaning gas removed by the filter 18 and an injection device 24 of compressed gas to the filter 18 are provided.

  The discharge unit 22 is open while the exhaust gas is introduced and dust is removed, but is closed when dust is removed. Further, compressed gas (compressed air) is supplied to the compressed gas injection device 24 from the outside. The compressed gas supply path is provided with a pulse valve, and the compressed gas can be instantaneously supplied into the filter 18 by opening and closing the pulse valve. Furthermore, although not shown in the drawing, an attractive gas that expands the filter 18 can be introduced into the filter 18 simultaneously with the supply of the compressed gas.

  Furthermore, a tapered dust collecting portion 30 is formed in the lower portion of the housing 16 so that the diameter gradually decreases as it goes downward. Part of the dust collecting unit 30, preferably the bottom, is provided with a dust discharge unit 32, and communicates with the dust discharge path 36. The dust discharge section 32 can be controlled manually or automatically. Usually, an open / close valve 34 is provided. The dust discharge unit 32 is closed while the exhaust gas is being introduced, and is opened when dust is removed. Further, when dust is wiped off, transport gas (air) is introduced into the dust discharge path 36 in the discharge direction. For this reason, if the dust discharge part 32 is opened at the time of dust wiping off, the atmospheric gas in the housing 16 will escape from the discharge part 32 to the discharge path 36 side at a stretch. That is, a gas flow directed in the dust discharge direction from the inside of the housing 16 is easily applied to the vicinity of the surface of the filter 18.

  Further, the dust removing means 14 includes a gas introducing means 40. The gas introduction means 40 is a gas introduction device that can introduce gas into the housing 16 from the outside. The configuration is not particularly limited. It is preferable that the gas introduction amount and the gas introduction time can be adjusted. The gas introduction means 40 is provided in the housing 16 preferably corresponding to the site where the filter 18 is installed, and can supply gas to the site. That is, gas can be supplied from the outside of the filter 18. It should be noted that it is sufficient that gas can be introduced into the filter 18 from the outside of the filter 18 either from the side or from above. From the viewpoint of the configuration of the apparatus, it is preferable that gas can be introduced from the side of the filter 18. The gas introduction means 40 is activated when dust is removed, and the dust discharge part 32 is in an open state so that the gas is introduced almost simultaneously with the injection of the compressed gas by the compressed gas injection device 24. It has become. The introduction of the gas is not particularly limited, but is controlled by the operation of an open / close valve capable of open / close control. The gas to be introduced is not particularly limited, but is preferably air.

  As the cleaning means 44, a conventionally known exhaust gas liquid cleaning apparatus can be used. Normally, a cleaning medium (aqueous) capable of dissolving harmful components in exhaust gas is used to dissolve and remove harmful components in the cleaning medium, and the purified gas can be discharged. Various known devices can be used as the exhaust gas treatment means. Various known forms of contact between the exhaust gas and the cleaning medium can be employed. For example, a method of introducing exhaust gas into a cleaning tank containing a cleaning medium, or a method of supplying a cleaning medium to the exhaust gas in a shower form may be employed.

  In the present invention, it is preferable to use means capable of removing dust in the exhaust gas. This is because stable operation is ensured in the means or process at a later stage. As the cleaning type dust collecting means, specifically, there is a cleaning type dust collecting device (scrubber). Various types can be employed depending on the form of contact between the exhaust gas and the cleaning medium. Preferably, a cleaning medium is supplied to the exhaust gas in a shower form (jet scrubber, spray tower, rotoclon, venturi scrubber), a form in which a gas and a cleaning medium are introduced into a column filled with a predetermined carrier (typical) Can be used, but a packed tower is preferable.

The cleaning means 44 preferably uses water as a cleaning medium. More preferred is soft water having a hardness of 10 or less, and particularly preferred is pure water to water having a hardness of 0. With such water, even if the cleaning means 44 contains a Si component, generation of Si-containing precipitates is avoided. This is because the precipitate is not generated unless there is a Si element (typically silica) and hydrofluoric acid generated in the exhaust gas, as well as metal element ions of Groups 1 and 2 of the periodic table including calcium. . Such metal element ions are calcium, sodium, potassium, etc., typically calcium. The hardness is 1 degree when 1 mg of calcium oxide is contained in 100 cm ^{3 of} water. Further, since hydrofluoric acid or the like is usually generated in the exhaust gas, the cleaning medium is preferably supplied together with an aqueous alkali solution such as sodium hydroxide.

Next, an exhaust gas detoxification process performed by the cleaning means 44 will be described. First, the exhaust gas treatment process is performed on the combustible gas and / or the combustion support gas generated in the film forming apparatus as they are or through a preliminary treatment process. Examples of the pretreatment step include a step of generating SiO ₂ from a reaction gas such as Si, F, NH _{3 in a} combustion type detoxification step and collecting the SiO ₂ with a filter. In this case, the combustible gas and / or the combustion-supporting gas are introduced into the exhaust gas treatment means 4 through the exhaust gas pipe after the preliminary treatment step, and the exhaust gas treatment step is performed. In the exhaust gas treatment means 4, for example, a high temperature such as a combustible gas or a flame is supplied, and at least one of the combustible gas and the combustion support gas in the exhaust gas is combusted.

  Next, the exhaust gas is introduced into the dust removing means 14 and a dust removing step is performed. The gas from which dust has been removed by the dust removing means 14 is introduced into the cleaning means 44 in a state where the amount of dust is lower than in the conventional case, and the cleaning process is performed. If dust is effectively removed in the dust removal step, the cleaning unit 44 may not need to perform dust removal. It is more effective if dust is removed at the same time in the cleaning means. By using pure water to water having a hardness of 0 as a cleaning medium in the cleaning process, even if Si components are present in the cleaning process, the generation of precipitates is effectively avoided, and the maintenance work associated therewith is also avoided. Stable operation is ensured.

  Hereinafter, the dust removal process using the dust removal means 14 shown in FIG. 4 will be particularly described. First, the dust removal process includes a dust collection process and a dust removal process. At the time of exhaust gas introduction, the exhaust gas introduction part 19 is opened and the discharge part 22 is also opened. On the other hand, in the dust discharge part 32, the valve 34 is closed and is in a closed state. The exhaust gas introduced in such a state passes from the outer surface of the filter 18 to the inside, and is cleaned and discharged from the discharge unit 22 through the filter 18 and the top plenum 20. Since the dust discharge part 32 of the dust collecting part 30 is closed in the housing 16, most of the fine particulate dust (typically about 0.1 to 1 μm silica particles) floats in the housing 16. The state is formed.

  When the discharge pressure of the exhaust gas from the discharge unit 22 is below a certain level or when the pressure loss is above a certain level, the dust collection process is stopped and the dust removal process is started. Prior to the dust removal step, the introduction of the exhaust gas is stopped, and the introduction unit 19 and the discharge unit 22 are closed. In the dust removal step, first, the discharge valve 34 is opened to open the dust discharge unit 32 of the dust collection unit 30. At this time, in the dust discharge path 36, gas is supplied in the dust discharge direction. Therefore, a downward gas flow is formed in the housing 16 or is easily formed. That is, a state in which a gas flow from the vicinity of the surface of the filter 18 toward the dust discharge direction is easily applied is formed.

  Next, the compressed gas is supplied to the filter 18 in a pulsed manner by adjusting the valve of the compressed gas injection device 24. Simultaneously with the supply of the compressed gas to the filter 18 or with a little time lag, the gas introduction means 40 is operated to supply external gas to the surface of the filter 18 from the outside. By supplying this gas, it is easy to form a gas flow in the housing 16 from the beginning toward the dust discharge direction. However, such a gas flow is more strongly formed. In particular, a stable gas flow having such directionality is formed in the vicinity of the surface of the filter 18. Due to such a gas flow, the fine dust floating in the housing is discharged from the discharge portion 32 of the dust collection portion 30. The gas flow replaces the atmospheric gas in the housing, and fine dust is discharged from the atmospheric gas.

  In this dust removing means 14, when the exhaust gas is introduced, the discharge part 32 is in a closed state, and there is no ability to discharge the fine dust floating in the housing, and the floating dust accumulates during the dust collection process. Both dust adhering to the filter 18 are discharged from the housing 16. By adopting such a discharge mode, dust can be discharged from the filter 18 and the atmosphere in a synergistic manner.

  According to such a dust removing means 14, dust can be effectively removed from the exhaust gas, so that not only the dust removing means 14 and the process but also the maintenance work in the subsequent processing means and process can be reduced, and stable operation can be secured. become. In particular, since fine silica particles can be eliminated, the life of the filter in the dust removing means 14 can be extended, and the generation of precipitates in the subsequent cleaning means and processes can be effectively avoided.

  The dust separated and discharged in the dust removing means or process of this embodiment is separately collected by the dust collecting means or process. Dust collection can be performed by a conventionally known method. It is also preferable to detect the pressure of the cleaning gas from the dust removing means or process and adjust the air volume of the discharge means, typically the discharge blower, based on the detected pressure. By supplying the air volume according to the pressure loss of the filter and discharging the cleaning gas, it is possible to carry out an appropriate dust collection process at low cost (operation cost and / or installation cost). In addition, the composition of the cleaning gas is stabilized.

  Next, another example of the apparatus of the present invention (Example 4) will be described with reference to FIG. In this example, in particular, in the dust removing means or process, at least m (m is an integer of 3 or more) dust removing means is provided, and each dust removing means is at least one dust removing means to remove dust. The process is carried out, and is configured to be switched and used so that the dust collection process is carried out with a maximum of (m−1) dust removing means. Note that m is preferably 6 or less, and more preferably 3 units. Moreover, although not shown in figure, this apparatus is equipped with the vacuum pump and pipe | tube which send waste gas to the waste gas treatment means 4, and this pipe | tube has a non-return valve. And the pipe | tube part between a vacuum pump and waste gas processing means is heated with the heater so that deposit may not precipitate in waste gas, The preset temperature of the said heater is the range of 165-180 degreeC.

  FIG. 5 shows a form in which three dust removing means 74, 76, 78 are provided as the dust removing means 72. In this embodiment, any known dust removing means can be used regardless of the type of dust removing means 74, 76, 78. Preferably, all the dust removing means are in the form of bag filters, more preferably. The dust wiping off means is a pulse air type bag filter, and more preferably, a compressed gas is supplied to the filter, and at the same time, a gas flow directed from the vicinity of the filter surface to the dust discharge side is supplied to the outside of the filter. It is a bug filter that can be formed. The most preferable form applied in this example is the form specified in Example 3.

  At least three dust removing means 74, 76, 78 are arranged in parallel to the exhaust gas supply path. The exhaust gas supply path connected to the exhaust gas treatment means is branched corresponding to each of the dust removing means 74, 76, and 78, and a valve 84 that adjusts the supply amount of exhaust gas or the presence or absence of supply to the branched pipes. , 86, 88 are provided. Further, exhaust pipes for the gas cleaned from the dust removing means 74, 76, and 78 are provided, and valves 94, 96, and 98 for adjusting the exhaust are provided.

  Even if any one of the dust removing means 74, 76, 78 performs the dust removal process or maintenance, the remaining two or one of the dust removing means 74, 76, 78 can ensure the necessary dust removal capability. It is preferable that the m dust removing units provided have the same dust removing capability, that is, the same filtration area. In this embodiment, each dust removing means 74, 76, 78 is designed to have the same dust removing capacity, that is, the same filtration area. At the same time, it is preferable that the maximum dust removal capacity, that is, the required total filtration area, can be ensured with a maximum of (m-1) units (preferably (m-1) units). Therefore, in this embodiment, each dust removing means has a dust removal capacity (filtration area) of 0.5 each, assuming that the required dust removal capacity (filtration area) is 1, and 1.5 dust removal capacity (filtration area) as a whole. ). In other words, two units ((m-1) when m = 3) have the necessary dust removal capability.

  Next, an exhaust gas dust removal process performed using the dust removal means 72 configured as described above will be described. In FIG. 5, the exhaust gas introduced from the exhaust gas treatment means is introduced into the dust removal means 76 and 78, and the dust removal process is performed. Therefore, the valves 84 and 94 are closed, and the valves 86, 88, 96, and 98 are open. In this case, the dust removing means 76 and 78 have a necessary dust removing capability in total or in total, so that an appropriate dust removing step is performed. When either one of the dust removing means has a necessary dust removing capability, one unit may be operated. On the other hand, since the use of the dust removing means 74 exceeds the necessary dust removing capacity, the dust removing means 74 can perform a dust removal process and maintenance as necessary.

  Furthermore, if any of the dust removal means 76, 78 exceeds the predetermined pressure loss and needs to be stopped, the introduction of the exhaust gas to the dust removal means is stopped, and the dust removal process or maintenance is performed. Then, the introduction of the exhaust gas into the dust removing means 74 is started to carry out the dust removing step. As described above, when a plurality of dust removing means are provided, and a part of the dust removing means has a necessary dust removing capacity, the remaining dust removing means is used in a dust wiping process, etc. Even if the operation is continued up to the range and the time required for the dust removal process and maintenance is minimized, the dust removal process and maintenance can be easily performed as necessary. For this reason, stable operation is always possible in a state where the pressure loss is low, and furthermore, stable dust removal is achieved, and a cleaning gas having a stable composition can be discharged.

  In particular, in this embodiment, all m dust removing means m have the same dust removing capacity, and (m-1) is provided with the necessary dust removing capacity, so that an efficient dust removing process with a minimum total dust removing capacity as a whole. Can be implemented. That is, the pressure loss is kept low by switching and using the dust removal process with at least one dust removal means and the dust collection process with at most (m−1) dust removal means. An efficient and good dust removal process can be carried out.

  Of course, if necessary, the dust removing step can be performed simultaneously with other dust removing means using dust removing means that exceeds the dust removing capability.

  In this example, the dust removing means or process has been particularly described. However, various modes included in Examples 1 to 3 can be applied to the dust removing means or process of this example. In particular, by providing a discharge blower that can change the air volume according to the pressure of the cleaning gas discharged from the dust removal means, the dust removal process, particularly the dust collection process, can be carried out at an optimal pressure. be able to.

  According to the present invention, when a film-forming exhaust gas containing a Si component is processed, the components in the exhaust gas are not deposited as precipitates in the pipe, and the pipe introduced into the exhaust gas processing apparatus is at an abnormally high temperature. Furthermore, thinning and clogging of the tube due to a reaction product of fluorine radicals and the tube material can be prevented. For this reason, it becomes possible to treat the exhaust gas efficiently and safely. Therefore, the exhaust gas treatment method and the treatment apparatus of the present invention can be effectively used for detoxifying exhaust gas used in, for example, a semiconductor or liquid crystal display module manufacturing process and film forming process.

FIG. 1 is a block diagram showing an example of the apparatus of the present invention. FIG. 2 is a block diagram showing another example of the apparatus of the present invention. FIG. 3 is a block diagram showing still another example of the apparatus of the present invention. FIG. 4 is a configuration diagram of an example of a bag filter used in the present invention. FIG. 5 is a block diagram showing still another example of the apparatus of the present invention. FIG. 6 is a configuration diagram of a conventional apparatus.

Explanation of symbols

2 Exhaust gas treatment device 4 Exhaust gas treatment device 14, 74, 76, 78 Dust removal device 16 Housing 18 Filter 19 Exhaust gas introduction unit 20 Top plenum 21 Tube sheet 22 Discharge unit 24 Compressed gas injection device 30 Dust collection unit 32 Dust discharge unit 34 Valve 36 Dust discharge path 40 Gas introduction means 44 Cleaning means 101 Vacuum box 102 Vacuum pump 103 Pipe 104 Check valve 105 Exhaust gas treatment means 106 Gas 107 Film forming device 108 Absorption filter 109 Heater 110 Hot gas introduction means

Claims (20)

A method for treating a film-forming exhaust gas containing a Si component, wherein the exhaust gas is introduced into an exhaust gas treatment step through a pipe by a vacuum pump, and a check valve is provided in the middle of the pipe. The valve has at least a valve body made of a fluororesin, and in the pipe, at least during the exhaust gas treatment step from the vacuum pump, is maintained at a temperature at which no precipitate is deposited from the exhaust gas by a heating means, In order to prevent the reaction between at least one of fluorine radicals and fluorine ions and metal ions in the tube material before the vacuum pump , the set temperature of the heating means is in the range of 130 to 190 ° C. A filter that absorbs at least one of the ions is provided, and at least one of fluorine radicals and fluorine ions in the exhaust gas is absorbed and removed. Including the Rukoto, exhaust gas treatment method.   The exhaust gas treatment method according to claim 1, wherein the heating means is a heater provided in the pipe.   The exhaust gas treatment method according to claim 1 or 2, wherein the heating means is means for introducing hot gas into the pipe. The exhaust gas treatment method according to any one of claims 1 to 3 , wherein the temperature and pressure of the pipe are measured. The exhaust gas treatment method according to any one of claims 1 to 4, further comprising: a dust removal step for removing Si-containing dust from the exhaust gas generated by the exhaust gas treatment step; and a cleaning step for aqueous cleaning of the dust exhaust gas. 6. The exhaust gas treatment method according to claim 5 , wherein a bag filter is used as dust removing means in the dust removing step. In the dust removing process of the bag filter, simultaneously with supplying compressed gas to the filter, a gas flow directed from the vicinity of the filter surface to the dust discharge side is applied to the outside of the filter. 6. The exhaust gas treatment method according to 6 . The dust removal process includes at least m (m is an integer of 3 or more) dust removal means, and each dust removal means implements a dust removal process with at least one dust removal means. The exhaust gas treatment method according to claim 6, wherein the dust collection process is performed by (m−1) dust removing means. The exhaust gas treatment method according to any one of claims 5 to 8 , wherein the gas removed in the dust removal step is discharged with an air volume corresponding to a discharge pressure of the gas. 10. The exhaust gas treatment method according to claim 5 , wherein pure water to water having a hardness of 0 is used as water introduced for cleaning in the cleaning step. An apparatus for treating a film-forming exhaust gas containing a Si component, comprising a heating means, an exhaust gas treatment means, and a vacuum pump for introducing the exhaust gas into the exhaust gas treatment means, the vacuum pump and the exhaust gas The processing means is connected by a pipe provided with a check valve in the middle thereof , at least the valve body of the check valve is made of fluororesin, and in the pipe, at least between the vacuum pump and the exhaust gas processing means. The heating means maintains a temperature at which precipitates are not deposited from the exhaust gas, the set temperature of the heating means is in the range of 130 to 190 ° C., and before the vacuum pump, fluorine radicals and fluorine In order to prevent the reaction between at least one of the ions and the metal ion in the tube material, a filter that absorbs at least one of fluorine radicals and fluorine ions is provided. , Thereby removing absorb at least one of fluorine radicals and fluorine ions in the exhaust gas, the exhaust gas treatment apparatus. The exhaust gas treatment apparatus according to claim 11 , wherein the heating means is a heater provided in the pipe. The exhaust gas treatment apparatus according to claim 11 or 12 , wherein the heating means is means for introducing hot gas into the pipe. The exhaust gas treatment apparatus according to any one of claims 11 to 13 , further comprising measurement means for measuring the temperature and pressure of the pipe. The exhaust gas treatment apparatus according to any one of claims 11 to 14, further comprising: a dust removal unit that removes Si-containing dust from the exhaust gas generated by the exhaust gas treatment unit; and a cleaning unit that performs aqueous cleaning of the dust exhaust gas. The exhaust gas treatment apparatus according to claim 15 , wherein the dust removing means is a bag filter. The bag filter further includes dust removal means, and as the dust removal means, the compressed gas is supplied to the filter, and at the same time, the gas flow directed from the vicinity of the filter surface to the dust discharge side to the outside of the filter. The exhaust gas treatment apparatus according to claim 16, further comprising a gas introduction unit that imparts the above. The dust removing means includes at least m (m is an integer of 3 or more) dust removing means, and each dust removing means performs a dust removal process with at least one dust removing means, and at most (m The exhaust gas treatment apparatus according to claim 16 or 17 , wherein the exhaust gas treatment apparatus is provided so as to be switchable so that the dust collecting process is performed by the dust removing means of the stand. The exhaust gas treatment apparatus according to any one of claims 15 to 18 , further comprising an exhaust unit capable of changing an air volume in accordance with a pressure of gas discharged from the dust removing unit. The exhaust gas treatment apparatus according to any one of claims 15 to 19 , wherein pure water to water having a hardness of 0 is used as water introduced for cleaning by the cleaning means.

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