JP2002276921A - Silane removing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an adhesion of silica generated when the silane is burned and removed from a silane-containing gas to a burner and to further expedite a mixture of an exhaust gas with a combustion air. SOLUTION: In a silane burning and decomposing apparatus of the silane- containing gas such as a semiconductor manufacturing exhaust gas or the like, a distal end of a flame rod 6 for monitoring a flame of a pilot burner 2 is not projected in a furnace but reversely disposed in a burner nozzle. Thus, the adhesion of a silica powder to the distal end of the flame rod can be prevented. Further, an outer peripheral gas channel 7 for injecting outer peripheral gas along a burner cylinder and a semiconductor manufacturing exhaust gas introducing tube 8 of a gas to be treated are installed on the outer periphery of the burner 2 toward a nozzle direction of the pilot burner. Thus, approaching of the silica powder to a nozzle opening can be suppressed, and the mixture of the gas to be treated with the combustion air is expedited to improve a decomposing efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing silane, and more particularly, to an apparatus for effectively removing silane contained in exhaust gas generated in a semiconductor manufacturing process or the like.

[0002]

2. Description of the Related Art In recent years, the problem of global warming has been highlighted, and it has been required to suppress the emission of exhaust gas such as carbon monoxide and carbon dioxide generated by consuming a large amount of fossil fuel. I have.

[0003] Exhaust gas discharged from a semiconductor manufacturing process (hereinafter also referred to as semiconductor manufacturing exhaust gas) includes Freon (P).
FC: Perfluorocarbons, contains perfluorocarbon) and silane (SiH ₄₎ is.

Of these, chlorofluorocarbon is used in a small amount, but its global warming potential is said to be 1,000 to 10,000 times that of carbon dioxide, and it is expected that semiconductor production will continue to increase in the future. I can't ignore it.

[0005] On the other hand, harmful components such as silane are contained in the semiconductor manufacturing exhaust gas in addition to CFCs.
It is also necessary to decompose harmful gases such as silane, and there is a need for the development of an exhaust gas treatment device that renders chlorofluorocarbons and silanes harmless.

To cope with this problem, an apparatus has been devised for simultaneously processing chlorofluorocarbon and silane in a high-temperature combustion furnace at a temperature of 1,000 ° C. or higher. Under the coexistence, it is difficult to collect 100% of the silica powder, which causes an adhesion failure in the device due to the silica powder and hinders continuous operation.

[0007] Therefore, as a process to deal with it,
A method of separately treating silane and chlorofluorocarbon has been devised.
First, semiconductor production exhaust gas is introduced into a silane combustion furnace to selectively burn only silane, and to collect silica powder generated in the absence of hydrogen fluoride. It is supposed to.

In a conventional silane combustion furnace, semiconductor production exhaust gas is sent into a combustion furnace heated to about 300 ° C., and the combustion air supplied from several air holes provided around the inner wall of the combustion furnace reacts with silane. Decompose by burning.

[0009] Silica (SiO ₂ ) powder generated by combustion decomposition of silane is collected by a bag filter or the like installed downstream. In this silane combustion furnace, the chlorofluorocarbon gas is not burned and decomposed, but is sent to the chlorofluorocarbon combustion furnace in the next process.

In a conventional silane combustion furnace, air and fuel whose flow rates have been adjusted are premixed in a nozzle, first ignited by a spark plug, and thereafter, flame is held by a high-temperature circulating gas in a flame holding section. To form a flame after the tip of the nozzle.
Therefore, flame rod for flame detection (flame detection rod)
Is installed at a position protruding into the combustion furnace from the nozzle end.

[0011]

The silane combustion furnace has two problems. One is that the generated silica powder (SiO ₂ ) adheres to the inside of the pilot burner nozzle to deteriorate the flame holding, or adheres to the frame rod installed in the burner to hinder the flame detection, thereby causing a misfire. It is a cause.

Second, if the combustion air supplied to the combustion furnace and the silane-containing gas are improperly mixed, a 100% decomposition reaction cannot be performed in the furnace, and the silica is burned in a downstream chlorofluorocarbon combustion furnace to produce silica. To produce a powder, where adhesion problems occur.

An object of the present invention is to provide a device for burning and removing silane from a silane-containing gas discharged from a semiconductor manufacturing process or the like, at least preventing poor combustion of a pilot burner due to adhesion of silica as a combustion product,
It is another object of the present invention to promote the mixing of the silane-containing gas with the combustion air to increase the efficiency of silane combustion decomposition.

[0014]

In order to solve the above-mentioned problems, the present invention relates to a silane removing apparatus, in which the tip of a flame rod for monitoring the flame of a pilot burner is not protruded into a furnace, but is conversely. It was located inside the burner nozzle. This can prevent the silica powder from adhering to the end of the frame rod.

In addition, stable combustion is improved by using a pilot burner that ensures stable flame holding as described below. That is, an enlarged portion that pushes the gas flow in the nozzle of the pilot burner to the nozzle inner wall side is installed on the frame rod, a net is provided at the tip of the pilot burner, and further,
By smoothly shaving the tip of the pilot bar nano nozzle from the inside to the outside, backflow into the nozzle is prevented and adhesion of silica powder to the inner wall of the nozzle is prevented. In this way, stable ignition flame holding is achieved.

Further, an outer peripheral gas is ejected along the burner cylinder around the outer periphery of the pilot burner, and a pipe for introducing a silane-containing gas such as a semiconductor manufacturing exhaust gas to be processed is provided.
By installing it toward the nozzle direction of the pilot burner, while preventing the silica powder from approaching the nozzle opening, the mixing of the gas to be treated and the combustion air is promoted,
The silane decomposition efficiency is improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The present invention has variously devised the structure of a pilot burner and the structure of a feed section for combustion air and a silane-containing gas in a silane removing apparatus.

FIG. 1 shows an embodiment of the silane removing apparatus of the present invention. A pilot burner 2 perpendicular to the vertical direction is installed on the upper part of the combustion furnace 1, and a frame rod (flame detection rod) 6 is coaxially inserted into a burner nozzle 8 of the pilot burner 2.

In the present invention, the tip of the frame rod 6 is located inside the opening of the nozzle 8. This prevented silica, which is a combustion product of silane, from adhering to the frame rod.

A flow path 7 for an outer peripheral gas (combustion air) 7a according to the present invention is provided on the outer periphery of the cylindrical nozzle of the pilot burner 2. Further, from the periphery of the pilot burner 2 in the upper part of the combustion furnace, an introduction pipe 3 for the silane-containing gas 3a is installed obliquely toward the tip of the burner nozzle. In the drawing, reference numeral 2a denotes pilot burner combustion air, and reference numeral 20 denotes a fuel such as LPG.

The air ejected from the outer gas passage 7 not only prevents the silica powder from adhering to the surface of the burner nozzle, but also mixes well with the silane-containing gas 3a at the tip of the burner nozzle. To promote the combustion decomposition reaction of silane in the gas to be treated. Further, the silane-containing gas introduction pipe 3 is installed obliquely toward the pilot burner nozzle to promote mixing with the combustion air.

FIG. 2 shows a comparative example of the silane combustion removing apparatus. In this example, the tip of the frame rod 6 projects from the nozzle opening of the pilot burner 2 into the furnace. Further, in the present invention, the combustion air 4 is supplied from the air hole 5 provided on the inner wall of the furnace without the outer gas flow path 7 provided along the burner nozzle 8 in the present invention. Further, the introduction pipe 3 for the semiconductor manufacturing exhaust gas (silane-containing gas) 3a is also connected to the nozzle 8
It is installed in the vertical direction in parallel with.

For this reason, the silica (SiO ₂ ) powder produced by the combustion reaction of silane easily adheres to the tip of the frame rod 6 projecting into the furnace, causing poor combustion. Further, since semiconductor manufacturing exhaust gas and combustion air are jetted in a direction deviated from the tip of the burner nozzle where the flame is formed, the mixing efficiency of these gases is not as good as that of the present invention.

Next, various improved examples of the pilot burner according to the present invention will be described. FIG. 3 is an enlarged sectional view of the pilot burner in FIG. The tip of the flame rod 6 for flame detection is located in the nozzle 8, and this alone prevents the silica powder from adhering to the rod.

FIG. 4 is an enlarged sectional view of a pilot burner in which an enlarged portion 10 for pushing a gas flow to an inner wall of a nozzle is installed in a frame rod 6. By forcing the gas flow to the inner wall side of the nozzle, a decrease in the flow velocity in the inner wall boundary layer is prevented, the formation of a backflow inside the inner wall is prevented, and the entrainment of silica powder inside the nozzle is suppressed.

FIG. 5 is a front view of the opening at the tip of the nozzle of the pilot burner, where a net 9 is installed to prevent the backflow from the nozzle opening into the interior by the net 9 to prevent the silica powder from approaching. This is an example in which it is prevented.

In the example shown in FIG. 6, the nozzle tip of the pilot burner is smoothly cut from the inside to the outside.
In this way, by forming the nozzle opening divergently, the smooth ejection of the combustion gas is enabled, the generation of the vortex at the nozzle tip edge is suppressed, and the backflow of the silica powder is prevented.

In addition, in the various examples of the present invention described above, regarding the introduction of the silane combustion air, it is also possible to use the outer gas passage 7 in the outer peripheral portion of the burner nozzle in FIG. 1 and the air hole 5 in FIG. It is within the scope of the invention.

FIG. 7 shows an example of a pilot burner used in the comparative example shown in FIG. The flow-regulated air 19 and fuel 20 are premixed in the nozzle 8,
First, it is ignited by the spark plug 12, and thereafter, the flame is held by the high-temperature circulating gas in the flame holding section 11, and a flame 21 is formed after the nozzle tip. Therefore, the tip of the flame rod 6 for flame detection is located at a position protruding into the furnace from the tip of the nozzle.

According to this embodiment, the silica powder (SiO ₂ ) generated by the combustion decomposition reaction of silane adheres to the inside of the pilot burner nozzle to deteriorate the flame holding, or to the flame rod installed in the burner. Adhesion can interfere with flame detection and cause a misfire.

Next, a specific process to which the silane removing apparatus according to the present invention is applied will be described. FIG. 8 is a schematic system diagram of an example of a semiconductor manufacturing exhaust gas treatment apparatus in which silane and chlorofluorocarbon are separately treated.

First, a semiconductor production exhaust gas 17 containing silane or chlorofluorocarbon is introduced into a silane combustion furnace 1 through an introduction pipe 3, where only silane is selectively burned, and there is no hydrogen fluoride (HF). The silica powder generated in the state,
The silica is completely collected by the silica collection filter 16.

Thereafter, the mixture is introduced into a chlorofluorocarbon decomposer 13, where the chlorofluorocarbon is decomposed at a gas temperature of 1,000 ° C. or higher, and the produced hydrogen fluoride is wet-removed in an absorption tower 14 to form a buffer tank 1
5 housed. Gas containing no harmful components is exhausted from the exhaust pipe 18.

By applying the present invention to this silane combustion furnace, in the silane combustion furnace, silica powder does not adhere to the pilot burner and the flame rod, and stable combustion over a long period of time is ensured. Almost 100% gas combustion decomposition efficiency can be achieved.

[0035]

According to the present invention, when silane in a silane-containing gas such as semiconductor manufacturing exhaust gas is burned and decomposed, silica as a product is prevented from adhering to a frame rod or a pilot burner. Poor combustion is prevented, and furthermore, the mixing of the gas to be treated and the combustion air is promoted, stable combustion over a long period of time is ensured, and the combustion decomposition efficiency of silane is also improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a silane combustion removal apparatus of the present invention.

FIG. 2 is a schematic configuration diagram showing a comparative example of a silane combustion removal device.

FIG. 3 is a sectional view showing an example of a pilot burner of the silane removing device of the present invention.

FIG. 4 is a sectional view showing another example of the pilot burner of the silane removing device of the present invention.

FIG. 5 is a sectional view showing still another example of the pilot burner of the silane removing device of the present invention.

FIG. 6 is a sectional view showing still another example of the pilot burner of the silane removing device of the present invention.

FIG. 7 is a sectional view showing a comparative example of a pilot burner of the silane removing device.

FIG. 8 is a schematic system diagram showing an example of a semiconductor exhaust gas treatment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion furnace 2 Pilot burner 3 Silane-containing gas introduction pipe 6 Flame rod (flame detection rod) 6a Flame rod tip 7 Outer gas (combustion air) flow path 8 Nozzle 9 Net 10 Enlarged part 11 Flame holding part 12 Spark plug 17 Silane Contained gas

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akira Baba 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Inside Kure Research Laboratories (72) Inventor Hidehisa Yoshiwara 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Co., Ltd. Kure Research Institute Co., Ltd. (72) Inventor Yasunori Katsuta 3-36 Takara-cho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Research Laboratory F-term (reference)

Claims (7)

[Claims] 1. A silane removal device comprising a pilot burner for burning and decomposing silane in a silane-containing gas, and a flame detection rod on a central axis of the pilot burner for maintaining a furnace temperature at a predetermined temperature or higher. In the apparatus, the tip of the flame detection rod is located inside a nozzle of the pilot burner. 2. The silane removing apparatus according to claim 1, wherein an enlarged portion for deflecting a combustion gas flow in a nozzle of the pilot burner toward an inner wall side of the nozzle is provided on the flame detecting rod. Characteristic silane removal equipment. 3. The silane removing apparatus according to claim 1, wherein the pilot burner has an opening at a tip thereof.
A silane removing device having a net installed. 4. One of claims 1, 2 and 3
3. The silane removing apparatus according to claim 1, wherein the tip of the inner wall of the nozzle of the pilot burner is cut so as to expand from the inside toward the outside. 5. The silane removing apparatus according to claim 1, wherein an outer peripheral gas flow path for ejecting an outer peripheral gas along a burner cylinder is provided on an outer periphery of the pilot burner. Characteristic silane removal equipment. 6. A pilot burner for combusting and decomposing silane contained in exhaust gas generated by the production of semiconductors. The pilot burner is provided on a central axis of the pilot burner for maintaining a furnace temperature at a predetermined temperature or higher. In the silane removal device having a flame detection rod, on the outer periphery of the pilot burner,
A silane removing device comprising an outer peripheral gas flow path for ejecting an outer peripheral gas along a burner cylinder. 7. The silane removing apparatus according to claim 1, wherein an exhaust gas introduction flow path for producing the semiconductor is installed toward a nozzle of the pilot burner. Silane removal equipment.