JP2014046297A - Electrothermal gas detoxification device - Google Patents

Abstract

An object of the present invention is to improve the decomposition ability of NF ₃ gas and lower the temperature of drainage.
An electrothermal gas abatement apparatus for detoxifying exhaust gas, comprising an electrothermal heater 11 and connected to a reactor 10 for decomposing gas by heat through a pipe inside the reactor 10 A circulating water container 20 in which the circulating water 21 is stored, a mechanism for supplying exhaust gas from the semiconductor manufacturing apparatus to a space on the water surface in the circulating water container 20 and guiding it into the reactor 10 through a pipe, and an air Alternatively, an inert gas is supplied below the surface of the water in the circulating water container 20, the circulating water 21 is bubbled and introduced into the reactor 10 through a pipe, and the gas decomposed in the reactor 10 is exhausted. A mechanism and a mechanism for guiding water generated by gas decomposition in the reactor 10 into the circulating water container 20.
[Selection] Figure 1

Description

  Embodiments described herein relate generally to an electrothermal gas abatement apparatus for detoxifying exhaust gas from a semiconductor manufacturing apparatus such as a CVD apparatus.

  In a CVD apparatus, a film is formed on a substrate by introducing various source gases, but some of the source gases are exhausted without being reacted. Further, a cleaning gas is introduced for periodic cleaning in the CVD apparatus, but a part of the cleaning gas is discharged from the CVD apparatus without being reacted. In view of this, a gas abatement apparatus for detoxifying these exhaust gases is provided at the subsequent stage of the CVD apparatus.

NF ₃ is used as a cleaning gas for the CVD apparatus, but about 1/3 to 1/2 of that is discharged from the CVD apparatus without being reacted. Since NF ₃ is a gas having toxicity similar to that of CO, it is necessary to detoxify the gas containing NF ₃ in advance when released into the environment. As an electrothermal gas abatement device that removes NF ₃ , there is a method in which exhaust gas containing NF ₃ is passed through a circulating water container, mixed with water vapor, guided into the reactor, and decomposed by reacting NF ₃ with water. It has been adopted.

However, this type of apparatus has a problem that the NF ₃ gas decomposition ability in the reactor is low. Furthermore, since the temperature of the water generated by the decomposition of NF ₃ is high, there is a problem that the temperature of the waste water discharged from the circulating water container becomes high.

JP-A-3-65218 Japanese Patent Laid-Open No. 9-85045

The problem to be solved by the invention is to provide an electrothermal gas abatement apparatus capable of improving the decomposition ability of NF ₃ gas and lowering the waste water temperature.

  The electrothermal gas abatement apparatus of the embodiment includes an electrothermal heater, a reactor that decomposes gas by heat, a circulating water container that is connected to the inside of the reactor via a pipe, and stores circulating water. And means for supplying exhaust gas from the semiconductor manufacturing apparatus to the space above the water surface in the circulating water container and guiding it into the reactor through the piping, and circulating the air, oxygen-containing gas, or inert gas. Means for supplying below the water surface in a water container, bubbling the circulating water and introducing it into the reactor via the pipe, means for exhausting gas decomposed in the reactor, and the reactor And means for guiding water generated by the decomposition of the gas into the circulating water container.

The schematic block diagram which shows the electrothermal type gas abatement apparatus concerning embodiment. The schematic block diagram which shows the electrothermal type gas abatement apparatus as a comparative example.

(Embodiment)
Hereinafter, an electrothermal gas abatement apparatus of an embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating an electrothermal gas abatement apparatus according to an embodiment.

  In the figure, reference numeral 10 denotes a reactor for decomposing and removing the exhaust gas discharged from the CVD apparatus by heat, and a cylindrical electric heater 11 is installed in the reactor 10. . The reactor 10 is connected to the circulating water container 20 by a first pipe 51 and a second pipe 52.

  Circulating water 21 is stored in the circulating water container 20, the pipe 51 is connected to a space above the water surface, and the pipe 52 is connected at a position below the water surface. An air introduction pipe 55 for introducing reaction air into the circulating water 21 is connected to the circulating water container 20. The introduction pipe 55 is connected to a portion below the water surface of the circulating water 21, and the circulating water 21 is bubbled by introducing air from the introduction pipe 55. Furthermore, the circulating water container 20 is connected to a water distribution pipe 56, and the circulating water 21 is drained from the water distribution pipe 56.

  The circulating water container 20 is connected to a third pipe 53 for connecting to a primary scrubber described later, and further connected to the pipe 52 is a fourth pipe 54 for connecting to a secondary scrubber described later. Yes.

  The exhaust gas from the CVD apparatus or the like is supplied to the primary scrubber 31 by the pump 40 and is introduced into the circulating water container 20 through the pipe 53. More specifically, the water is introduced into a space above the water surface of the circulating water 21 in the circulating water container 20. Although not shown in the figure, the circulating water 21 is circulated to the scrubbers 31 and 32 and other parts that require cooling.

  The exhaust gas introduced into the circulating water container 20 is introduced into the reactor 10 through the pipe 51. The exhaust gas decomposed in the reactor 10 is supplied to the secondary scrubber 32 through the pipes 52 and 54 and discharged from the duct. Further, the water accumulated in the lower part of the reactor 10 is introduced into the circulating water container 20.

  Next, the operation of the apparatus configured as described above will be described.

The exhaust gas containing NF ₃ used for cleaning of the CVD apparatus or the like is supplied to the primary scrubber 31 by the pump 40, and a part of the exhaust gas (for example, ammonium silicofluoride: (NH ₄ ) ₂ SiF) is supplied by the scrubber 31. ₆ ) is removed. The exhaust gas that has passed through the primary scrubber 31 is introduced into the circulating water container 20 through the pipe 53 and further introduced into the reactor 10 through the pipe 51.

  Here, since the circulating water 21 is bubbled by air in the circulating water container 20, more water can be introduced into the reactor 10. This is because sufficient moisture is taken into the air itself by bubbling in the circulating water container 20, and further mist is generated by bubbling, which is easily carried to the reactor 10. Further, when the water surface is shaken by bubbling, the contact area between the water surface and the exhaust gas increases, and moisture is taken into the exhaust gas more efficiently.

In the reactor 10, the exhaust gas introduced through the pipe 51 is decomposed by heating by the heater 11. In particular, moisture is required for gas decomposition of NF ₃ , and the reaction formula in this case is as follows.

4NF ₃ + 6H ₂ O → 12HF + 2N ₂ + 3O ₂
2NF ₃ + 3H ₂ O → 6HF + NO + NO ₂
Here, as in this embodiment, by directly introducing the reaction air into the circulating water 21 and bubbling, the exhaust gas introduced through the primary scrubber 31 can sufficiently contain moisture. For this reason, more water can be introduced into the reactor 10, thereby increasing the decomposition ability of the NF ₃ gas.

  The gas decomposed in the reactor 10 is supplied to the secondary scrubber 32 through the pipes 52 and 54. In the scrubber 32, the exhaust gas that could not be decomposed in the reactor 10 is removed and the gas is cooled. And the exhaust gas which passed the scrubber 32 is discharged | emitted from a duct.

  Here, for comparison, the configuration of a general electrothermal gas abatement apparatus is shown in FIG. The basic configuration is the same as in FIG. 1 except that the position of the air introduction pipe 55 connected to the circulating water container 20 is different, and the air is not in the circulating water 21 but in the space above the water surface of the circulating water 21. Has been supplied to.

Also in the configuration of FIG. 2, it is possible to introduce moisture into the gas introduced through the primary scrubber 31 and introduce it into the reactor 10. However, sufficient moisture is required for the decomposition of NF ₃ , and it cannot be said that sufficient moisture can be supplied by this method, and the efficiency of gas decomposition is poor. Furthermore, the drainage temperature is as high as 60 ° C.

On the other hand, by introducing the reaction air directly into the circulating water 21 and bubbling as in the present embodiment, the gas introduced through the primary scrubber 31 can sufficiently contain moisture. For this reason, more water can be introduced into the reactor 10, thereby increasing the decomposition ability of the NF ₃ gas. Moreover, since the circulating water 21 is bubbled with the reaction air, the circulating water 21 can be cooled, and thereby the temperature of the circulating water 21 can be lowered. This means a decrease in drainage temperature and contributes to a reduction in the heat load on the drainage line.

When this embodiment shown in FIG. 1 and the apparatus shown in FIG. 2 are used under the same conditions, the NF ₃ gas decomposition reactivity is increased and the NF ₃ outlet concentration is reduced to 1/6 or less in this embodiment. . Furthermore, the circulating water temperature also decreased from 60 ° C. to 40 ° C. In this embodiment, even when the circulating water temperature was lowered, the amount of water in the bubbling reaction air was large (because it was high humidity air), and the NF ₃ gas decomposition reactivity was good.

In the above description, the exhaust gas containing NF ₃ used for the cleaning of the CVD apparatus has been described. However, source gases such as silane (SiH ₄ ) and phosphine (PH ₃ ) used for film formation in the CVD apparatus are shown in FIGS. Any device can be sufficiently detoxified. That is, the electrothermal gas abatement apparatus of the present embodiment is particularly effective for the abatement of the cleaning gas as well as the source gas of the CVD apparatus.

As described above, according to the present embodiment, the circulating water 21 is bubbled by air in the circulating water container 20, so that more water can be introduced into the reactor 10 when introducing the exhaust gas into the reactor 10. It becomes possible. Therefore, to improve the resolution capability of the NF ₃ gas, it is possible to harm efficiently dividing the NF ₃ gas. Further, since the circulating water 21 is bubbled with air, the circulating water can be cooled, and there is an advantage that the temperature of the drainage discharged from the circulating water container 20 can be lowered.

(Modification)
In addition, this invention is not limited to embodiment mentioned above.

In the embodiment, the primary scrubber is provided on the gas inlet side of the circulating water container and the secondary scrubber is provided on the gas exhaust side of the reactor. However, these scrubbers are not necessarily provided. Since the primary scrubber removes components that cannot be removed by heat treatment in the reactor, there are few components (eg, ammonium silicofluoride) that cannot be removed by heat treatment in the exhaust gas supplied from the CVD equipment. Can omit the primary scrubber. Further, since the secondary scrubber removes gas that could not be removed by the reactor, the secondary scrubber may be omitted if the gas containing NF ₃ can be sufficiently removed by the reactor. Is possible.

  The configuration of the reactor is not limited to that shown in FIG. 1 and can be changed as appropriate according to the specifications. For example, the shape of the heater is not limited to a cylindrical shape, and may be any shape that can sufficiently heat the introduced gas.

  The gas introduced below the surface of the circulating water container is not necessarily limited to air in the atmosphere, and cold dry air can be used to cool the circulating water more efficiently. Further, an inert gas such as a gas containing oxygen or nitrogen can be used.

The electrothermal gas abatement apparatus of the present invention is not necessarily limited to the treatment of exhaust gas in a CVD apparatus, and can be applied to various semiconductor manufacturing apparatuses that use a gas containing NF ₃ for cleaning.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Reactor 11 ... Electric heater 20 ... Circulating water container 21 ... Circulating water 31 ... Primary scrubber 32 ... Secondary scrubber 40 ... Pump 51, 52, 53, 54 ... Pipe 55 ... Air introduction pipe 56 ... Water distribution pipe

Claims (5)

A reactor equipped with an electric heater, which decomposes gas by heat;
A circulating water container connected to the inside of the reactor via a pipe and containing circulating water;
Means for supplying the exhaust gas from the semiconductor manufacturing apparatus to the space above the water surface in the circulating water container, and guiding it into the reactor via the piping;
Means for supplying air, oxygen-containing gas, or inert gas below the water surface in the circulating water container, bubbling the circulating water and introducing the circulating water into the reactor via the piping;
Means for exhausting gas decomposed in the reactor;
Means for guiding water produced by the decomposition of the gas in the reactor into the circulating water container;
An electrothermal gas abatement apparatus comprising:   2. The electrothermal gas abatement apparatus according to claim 1, wherein a first scrubber for removing a part of the exhaust gas is provided on the exhaust gas introduction side of the circulating water container.   3. The electric heating according to claim 2, wherein a second scrubber for removing the gas that could not be decomposed in the reactor is provided on the exhaust side of the gas decomposed in the reactor. Gas abatement system.   The circulating water container has a space above the water level of the circulating water connected to the reactor by a first pipe, and a portion below the water level of the circulating water is connected to the reactor by a second pipe. The electrothermal gas abatement apparatus according to claim 1.   The electric scrubber according to claim 4, wherein the primary scrubber is connected to the circulating water container by a third pipe, and the secondary scrubber is connected to the reactor by a fourth pipe. Gas abatement device.

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