JP2005098680A - Harmful gas cleaning facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning facility capable of stably removing a harmful gas discharged from a semiconductor manufacturing process in safety for a long time by inhibiting the lowering of a decomposition ratio of a treated harmful gas and the accumulation of powdered matter on a wall face of a decomposition chamber without using a large-scaled or complicated constitution. <P>SOLUTION: In this cleaning facility for removing the harmful gas discharged from the semiconductor manufacturing process by thermally decomposing the harmful gas by the combustion waste gas or flame obtained by burning the fuel, a side face of the thermal decomposition chamber is a wall having air permeability and heating insulating property, and the oxygen-containing gas is introduced into the thermal decomposition chamber through the wall. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a purification device for removing harmful gas containing harmful components discharged from a semiconductor manufacturing process. More specifically, harmful gases emitted from the semiconductor manufacturing process are brought into contact with combustion exhaust gas or flame obtained by burning fuel at a high temperature in the presence of oxygen, and are harmless by pyrolysis. The present invention relates to a purification device for changing to a substance that can be rendered harmless.

  With the development of the semiconductor industry in recent years, a great variety of gases have been used in the semiconductor manufacturing process. However, many of these gases are harmful to the human body and the environment, and it is essential to purify them before they are discharged outside the factory. Combustion-type purification methods that decompose these gases by burning them are convenient methods that can be applied regardless of the composition and physical properties of the exhaust gas. It is more efficient than the purification method.

  Hazardous gas treated by the combustion purification method is mixed with fuel gas such as propane, LPG, LNG, air or oxygen, and inert gas as necessary, and burns in the combustion chamber, harmless oxide or easily detoxified It becomes a material that can be processed. Conventional combustion purifiers used in the past introduce combustion chambers for burning harmful gases, hazardous gases containing harmful gas components to be treated, fuel gases, oxygen-containing gases such as air into the combustion chambers. Each pipe for carrying out, and the exhaust port for discharging | emitting the gas after combustion from a combustion chamber are comprised. In addition to these, there is a device in which a flame holder having a conical shape or a similar shape is installed to keep the flame in a stable state.

  In the combustion type purification apparatus having such a configuration, the harmful gas is burned and exhausted from the gas discharge port and released to the atmosphere or sent to the next processing apparatus. However, when the gas to be treated is a gas such as silane, phosphine, arsine, and diborane, solid particulate oxides of silicon, phosphorus, arsenic, and boron are generated by combustion, respectively, and most of them are in the combustion chamber. It passes through and is processed in a later process, but a part is accumulated as a pulverized product in the combustion chamber, causing problems as described below.

  That is, the above-mentioned pulverized material is generated at the start of combustion of harmful gas and deposited on the inner wall of the combustion chamber, and the adhesion area and thickness increase with the passage of combustion time. As a result, uniform mixing of harmful gas and fuel gas, air, oxygen, etc. is hindered and complete combustion is hindered, resulting in not only lowering the combustion temperature and lowering the decomposition rate of harmful gases to be treated, but also If the amount of deposits of chemicals is large, there is a risk of misfire.

Therefore, a scraper and a fixed projection that rotate and reciprocate in the vertical direction in the combustion chamber are provided to scrape and remove the accumulated dust (JP-A-11-193916), or the theoretical amount of fuel Purification method in which a semiconductor production exhaust gas is introduced into a thermal energy holding gas obtained by combustion and pyrolyzed by supplying the excess air in another section to complete the oxidation reaction. And a purifier (Japanese Patent Laid-Open No. 11-211036) have been proposed.
JP-A-11-193916 Japanese Patent Application Laid-Open No. 11-211036

  However, the purification device described in Japanese Patent Application Laid-Open No. 11-193916 requires a driving unit for rotating the scraper and reciprocating in the direction of the rotation axis, which is disadvantageous in that the device becomes complicated and expensive. there were. In addition, the deposition of solid deposits when using a scraper and fixed projections is much better than when they are not used, but periodic disassembly and cleaning cannot be avoided, and the equipment is complex. There was an inconvenience that a lot of labor was required for maintenance.

  The purifying apparatus described in Japanese Patent Application Laid-Open No. 11-211036 is free from the risk of misfiring because no flame is used when thermally decomposing harmful gases from the semiconductor manufacturing process. Since the generation of particulate oxide is suppressed, the amount of powdered material deposited on the wall in the decomposition chamber can be reduced. However, there is an inconvenience that an oxidation furnace is required in the next step, resulting in a large and complicated apparatus. .

  Therefore, the problem to be solved by the present invention is to solve these drawbacks of the prior art, and to reduce the decomposition rate of the harmful gas to be treated without using a large or complicated structure, It is an object of the present invention to provide a harmful gas purification device capable of suppressing deposition and capable of performing safe and stable purification over a long period of time.

  As a result of intensive studies to solve these problems, the present inventors have conducted a thermal decomposition in a purifying apparatus that purifies harmful gases discharged from a semiconductor manufacturing process by thermal decomposition (or combustion) with combustion exhaust gas or flame. By making the side of the chamber a wall with air permeability and heat insulation, and introducing oxygen-containing gas into the pyrolysis chamber through this wall, it is possible to efficiently treat harmful gases without using a large or complicated structure. It has been found that it can be easily and easily decomposed, can suppress the accumulation of pulverized material on the wall of the decomposition chamber, and can be safely and stably purified over a long period of time, and reaches the harmful gas purification device of the present invention. did.

  That is, the present invention is a purifying device that thermally decomposes and purifies harmful gas discharged from a semiconductor manufacturing process by combustion exhaust gas or flame obtained by burning fuel, and includes at least a harmful gas pyrolysis chamber, combustion Nozzle for introducing exhaust gas or flame into the pyrolysis chamber, nozzle for introducing harmful gas into the pyrolysis chamber, means for introducing oxygen-containing gas into the pyrolysis chamber from the side through a breathable heat insulating wall, and heat 1. A harmful gas purification apparatus comprising a discharge port for discharging the decomposed gas to the outside.

  The present invention is applied to a purification apparatus that purifies harmful gas discharged from a semiconductor manufacturing process by thermal decomposition with combustion exhaust gas or flame obtained by burning fuel, and particularly reacts with oxygen to remove pulverized material. When processing the gas containing the harmful | toxic component to produce | generate, an effect is exhibited at the point which can suppress the accumulation of the powdered material in a decomposition chamber wall surface.

Examples of harmful gas components that can be treated by the purification apparatus of the present invention include hydride gases such as arsine, phosphine, silane, disilane, dichlorosilane, diborane, hydrogen selenide, and germane, boron trifluoride, boron trichloride, and tetrafluoride. Acid gases such as silicon, silicon tetrachloride, titanium tetrachloride, aluminum chloride, germanium tetrafluoride, tungsten hexafluoride, basic gases such as ammonia, monomethylamine, dimethylamine, trimethylamine, hydrazine, perfluorocarbon, hydrofluorocarbon, etc. Can be exemplified.
Moreover, propane gas, natural gas, etc. can be used as fuel gas. These gases are used together with an inert gas such as nitrogen as necessary.

Hereinafter, although the purification apparatus of the waste gas of this invention is demonstrated in detail based on FIG.1 and FIG.2, this invention is not limited by these.
FIG. 1 is a longitudinal sectional view showing an example of the harmful gas purification apparatus of the present invention. FIG. 2 is a partially enlarged plan sectional view of a breathable heat insulating wall in the purification apparatus of the present invention.
As shown in FIG. 1, the purification apparatus for harmful gas of the present invention introduces at least a thermal decomposition chamber 1 for harmful gas, a nozzle 2 for introducing combustion exhaust gas or flame into the thermal decomposition chamber, and introduces harmful gas into the thermal decomposition chamber. A nozzle 3, an oxygen-containing gas introduction port 4, a breathable heat insulating wall 5, and a discharge port 17 that discharges the pyrolyzed gas to the outside. The oxygen-containing gas supplied from the introduction port 4 into the apparatus is The purification device is configured to be introduced into the thermal decomposition chamber from the side surface through the breathable heat insulating wall 5. In the present invention, the means for introducing the oxygen-containing gas into the thermal decomposition chamber from the side surface through the breathable heat insulating wall includes an oxygen-containing gas inlet and an oxygen-containing gas channel, and the oxygen-containing gas channel is It is provided over the entire outer periphery of the breathable insulating wall.

  In the harmful gas purification apparatus of the present invention, a breathable heat insulating wall 5 having a cylindrical shape, a rectangular tube, a polygonal tube, or a similar cylindrical shape is provided on the side surface of the noble gas pyrolysis chamber 1. . In the present invention, harmful gases come into contact with high-temperature combustion exhaust gas or flame in the pyrolysis chamber, and also come into contact with oxygen-containing gas such as air supplied from the heat insulating wall 5 on the side of the pyrolysis chamber. The contained harmful components are pyrolyzed. At this time, although a pulverized product is generated depending on the type of harmful component, accumulation of the pulverized product on the wall of the pyrolysis chamber can be suppressed by the flow of the oxygen-containing gas as shown by an arrow in FIG.

  The constituent material of the heat insulating wall 5 is not particularly limited as long as it has corrosion resistance against harmful components, heat resistance capable of withstanding a thermal decomposition temperature, and heat insulating properties, but a preferable constituent material is ceramic. Can do. Among ceramics, alumina, silica, titania and the like are preferable in terms of corrosion resistance, heat resistance, and heat insulation. Moreover, as a form of the heat insulating wall 5, an oxygen-containing gas having a flow rate necessary for the thermal decomposition of harmful components can be stably supplied to the thermal decomposition chamber 1 for a long time from the entire wall surface on which the powdered material comes. It is necessary to have a configuration that can.

  As a form of the surface of the heat insulation wall 5, a structure as shown, for example in FIG. 2 can be mentioned. 2 (a) and 2 (b) are partially enlarged plan sectional views of a ceramic wall having needle holes, and the hole diameter (diameter) is usually 0.01 to 3.0 mm, preferably 0.02 to 1.. 0 mm. The hole 18 is not limited to a circular shape, and the size of the hole in such a case is a size corresponding to the above-mentioned hole diameter. The holes can be arranged regularly and vertically or randomly. FIG. 2 (c) is a partially enlarged plan sectional view of a wall having a linear gap 19. The gap is usually 0.005 to 2.0 mm, preferably 0.01 to 1.0 mm. FIG. 2 (d) is a partially enlarged plan sectional view of a wall having a lattice window-like gap 20. The gap is usually 0.01 to 3.0 mm, preferably as a side length when converted to a square. Is 0.02 to 1.0 mm. Further, the form of the surface of the heat insulating wall 5 is not limited to these. For example, in addition to these, a porous ceramic having pores, a laminate in which a large number of fibrous ceramics are stacked, and a large number of particulate ceramics The form of the laminated body etc. which were laminated | stacked can be mentioned.

If the holes and gaps of the heat insulating wall are larger than the above ranges, the flow of oxygen-containing gas to the pyrolysis chamber is biased, and there may be a portion where the gas flow rate is high and a portion where the gas flow rate is high, and the gas flow rate is low. There is a possibility that powdered material accumulates in the part. Moreover, when smaller than the said range, there exists a possibility that a hole and a gap | block may be obstruct | occluded by powdered material etc. in a short time. Further, the air-permeable portion of the heat insulating wall is preferably made to have a porosity or porosity of about 50 to 90% in any form. When the porosity or porosity is less than 50%, there is a possibility that the powdered material is deposited on the wall surface. When the porosity or porosity exceeds 90%, the strength of the heat insulating wall may be reduced.
In addition, the thickness of the heat insulating wall cannot be generally specified by the size of the thermal decomposition chamber, the decomposition conditions of harmful gas, the constituent material of the heat insulating wall, etc., but when using ceramic, usually 2-50 mm, Preferably it is 5-30 mm.

  In the harmful gas purification apparatus of the present invention, the oxygen-containing gas flow path 6 is usually provided over the entire outer periphery of the air-permeable heat insulating wall as described above. The width of the flow path of the oxygen-containing gas is usually 5 to 200 mm, preferably 10 to 100 mm. When processing harmful gas, the temperature of the thermal decomposition chamber becomes a high temperature of 500 to 1200 ° C. With such a configuration, it is possible to prevent the heat of the thermal decomposition chamber from diffusing outside. In addition, the outer wall of the flow path of the oxygen-containing gas matches the shape of the heat insulating wall 5, and is usually a cylinder, a rectangular tube, a polygonal cylinder, or a similar cylindrical shape.

  In the harmful gas purification apparatus of the present invention, the fuel and the oxygen-containing gas are mixed and burned immediately before the pyrolysis chamber. When the fuel is burned, the tip of the flame 7 may or may not enter the pyrolysis chamber. As shown in FIG. 1, the nozzle 3 for introducing harmful gas into the thermal decomposition chamber is usually installed on the outer peripheral side of the nozzle 2 for introducing combustion exhaust gas or flame 7 into the thermal decomposition chamber. With such a configuration, when the harmful gas is pyrolyzed by the combustion exhaust gas, the combustion exhaust gas can be supplied to the thermal decomposition chamber while maintaining a high temperature. The temperature of the combustion exhaust gas when introduced into the pyrolysis chamber is usually about 1000 to 1500 ° C. Further, the gas pressure in the pyrolysis chamber is not particularly limited, and is usually a normal pressure, but is treated under a reduced pressure such as 10 KPa (absolute pressure) or a pressurized pressure such as 0.5 MPa (absolute pressure). It is also possible to do.

The pyrolyzed gas is released into the atmosphere or sent to the next processing step. In the case of being sent to the next processing step, the harmful gas purification apparatus of the present invention uses this gas. It is also possible to equip equipment for carrying out such processing steps.
The water tank 12 and scrubber equipment shown in FIG. 1 are provided for the harmful gas treated by the harmful gas purification apparatus of the present invention, removal of pulverized substances contained in the treated gas, and newly produced harmful components (easily detoxified). Component), which is not essential equipment in the present invention, but it is preferable to provide these equipment. In other words, a harmful gas purification device in which a pulverized product removal unit and / or an acid gas removal unit is provided on the discharge side of the thermal decomposition chamber is preferable.

For example, when a hydride such as arsine, phosphine, silane, diborane or the like is processed by the harmful gas purifying apparatus of the present invention, solid particulate oxides such as arsenic, phosphorus, silicon, and boron are generated by combustion. In addition, when a halide such as boron trifluoride, boron trichloride, silicon tetrafluoride, silicon tetrachloride, or C ₂ F ₆ is treated, a new acidic gas such as hydrogen chloride or hydrogen fluoride (which is easily harmless) Component) that can be converted into In the purification apparatus of FIG. 1, the powdered material can be removed mainly by watering from the spray nozzle 9 and trapping in the perforated plate 14. Further, hydrogen chloride, hydrogen fluoride, and the like can be mainly removed by the filler 15. Further, the demister 16 can also remove moisture. In FIG. 1, 8 is a cooling pipe, 10 is a flow meter, 11 is a pump, 13 is a water distribution pipe, and 17 is a discharge port for discharging the pyrolyzed gas to the outside.

  The toxic gas purification apparatus of the present invention makes toxic gas discharged from a semiconductor manufacturing process come into contact with combustion exhaust gas or flame obtained by burning fuel at a high temperature in the presence of oxygen, and thermally decomposes the toxic gas. In the purification apparatus, the side surface of the thermal decomposition chamber is a wall having air permeability and heat insulation properties, and the oxygen-containing gas is introduced into the thermal decomposition chamber through the wall. With such a configuration, thermal diffusion from the thermal decomposition chamber can be prevented, and powdered materials are less likely to accumulate on the decomposition chamber wall surface due to the flow of the oxygen-containing gas. Accordingly, the harmful gas purification device of the present invention is a small and simple device that can efficiently and easily decompose the harmful gas to be treated and suppress the accumulation of pulverized substances on the wall of the decomposition chamber. In addition, safe and stable purification is possible for a long time. In addition, maintenance work can be greatly reduced.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

(Production of purification equipment)
As shown in FIG. 1, a purification device having an outer wall made of stainless steel (SUS316) and having a height of 2000 mm was manufactured. As the heat insulating wall on the side surface of the pyrolysis chamber, a cylinder made of alumina having micropores as shown in FIG. 2B was used. The heat insulating wall had a diameter of 300 mm, a length of 600 mm, and a thickness of 25 mm, and had micropores corresponding to a diameter of 10 to 100 μm. Further, a stainless steel cylinder having a diameter of 480 mm and a thickness of 3 mm was used for the outer wall on the outside. Further, the inner diameter of the nozzle for introducing combustion exhaust gas into the thermal decomposition chamber was 32 mm, the inner diameter of the nozzle for introducing harmful gas into the thermal decomposition chamber was 44 mm, and the length was 200 mm.

  A water tank with a length of 1000 mm, a width of 600 mm, and a height of 500 mm is installed at the bottom of the purification device, and a scrubber having a porous plate, a filler mainly made of polypropylene resin, and a demister is installed on the right side of the purification device. did. In addition, a spray nozzle, flow meter, pump, etc. were connected to complete the purification device.

(Evaluation of purification equipment)
After water was poured into the water tank until the depth reached 350 mm, the pump was operated to eject water from the spray nozzle. In addition, combustion exhaust gas obtained by mixing and burning propane (flow rate 30 L / min) and air (flow rate 715 L / min) is introduced into the thermal decomposition chamber from the nozzle, and air is flowed from the side at a flow rate of 200 L / min. It was introduced into the pyrolysis chamber through an insulating wall. Next, nitrogen gas (flow rate: 490 L / min) containing silane (flow rate: 10 L / min) as a harmful gas was introduced from the nozzle into the thermal decomposition chamber, and thermal decomposition treatment was performed.

  The thermal decomposition treatment of silane is performed for 120 hours. During this time, in order to confirm the change in the combustion state of silane, the temperature in the decomposition chamber is measured by a temperature sensor installed in the decomposition chamber, and a part of the gas discharged from the discharge port Were sampled and the concentration of silane was measured. Note that TG-4000XA (detection lower limit 1, 5 ppm) manufactured by Bionics Co., Ltd. was used for measurement of the silane concentration. The results are shown in Table 1. (ND in Table 1 indicates that it could not be detected.) The state of solid deposits after the experiment was only slightly deposited on the wall of the combustion chamber. Moreover, it was confirmed from the measurement result of combustion chamber temperature, and the measurement result of the silane density | concentration of a combustion chamber exit that silane burned completely.

Comparative Example 1
In the manufacture of the purification apparatus of Example 1, a non-breathable alumina cylinder (diameter 300 mm, length 500 mm, thickness 25 mm) was used as the heat insulating wall on the side surface of the pyrolysis chamber, and from the space 100 mm above the heat insulating wall. A purification device was manufactured in the same manner as in Example 1 except that the oxygen-containing gas could be introduced into the thermal decomposition chamber.
Table 1 shows the results of thermal decomposition and evaluation of silane using this purification device in the same manner as in Example 1. The state of solid deposits after the experiment was in a state where a large amount was deposited on the wall of the combustion chamber. Moreover, from the measurement result of the silane concentration at the outlet of the combustion chamber, it was confirmed that the decomposition rate of silane decreased with time.

The longitudinal cross-sectional view which shows the example of the purification apparatus of the noxious gas of this invention Partially enlarged plan sectional view of a breathable heat insulating wall in the purification apparatus of the present invention

Explanation of symbols

1 Noxious gas pyrolysis chamber 2 Nozzle for introducing combustion exhaust gas or flame into the pyrolysis chamber 3 Nozzle for introducing noxious gas into the pyrolysis chamber 4 Oxygen-containing gas inlet 5 Breathable heat insulating wall 6 Oxygen-containing gas flow Road 7 Flame 8 Cooling piping 9 Spray nozzle 10 Flow meter 11 Pump 12 Water tank 13 Drainage piping 14 Perforated plate 15 Filler 16 Demister 17 Exhaust port for discharging the pyrolyzed gas to the outside 18 Hole 19 Linear gap 20 Grid window Gap

Claims (9)

  A purification device for thermally decomposing and purifying harmful gas discharged from a semiconductor manufacturing process by combustion exhaust gas or flame obtained by burning fuel, comprising at least a thermal decomposition chamber, combustion exhaust gas or flame of harmful gas A nozzle for introducing into the pyrolysis chamber, a nozzle for introducing harmful gas into the pyrolysis chamber, means for introducing an oxygen-containing gas into the pyrolysis chamber from the side through a breathable heat insulating wall, and a gas after pyrolysis A harmful gas purification device comprising a discharge port for discharging to the outside.   The harmful gas purification device according to claim 1, wherein the breathable heat insulating wall has a cylindrical shape, a rectangular tube, a polygonal tube, or a cylindrical shape similar thereto.   The means for introducing the oxygen-containing gas into the thermal decomposition chamber from the side through the breathable heat insulating wall comprises an oxygen-containing gas inlet and an oxygen-containing gas flow path, and the oxygen-containing gas flow path is a breathable heat insulating wall. The harmful gas purification device according to claim 1, which is provided over the entire outer periphery of the wall.   The harmful gas purification device according to claim 1, wherein the breathable heat insulating wall is made of ceramic.   Breathable thermal insulation wall is made of ceramic with needle holes, ceramic with linear gaps, ceramic with lattice window gaps, porous ceramics, multiple fibrous ceramic laminates, or multiple particulate ceramics The harmful gas purification device according to claim 1, which is configured of a laminate.   The harmful gas purification apparatus according to claim 1, wherein the nozzle for introducing the harmful gas into the thermal decomposition chamber is installed on the outer peripheral side of the nozzle for introducing the combustion exhaust gas or flame into the thermal decomposition chamber.   The harmful gas purification apparatus according to claim 1, wherein the harmful gas discharged from the semiconductor manufacturing process is a gas containing a harmful component that reacts with oxygen to produce a powdered product.   The harmful gas purification apparatus according to claim 1, wherein the harmful gas discharged from the semiconductor manufacturing process is a gas containing a harmful component that generates an acidic gas. The harmful gas purification apparatus according to claim 1, wherein a pulverized product removal unit and / or an acid gas removal unit is provided on a discharge side of the thermal decomposition chamber.

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