JP2000153128A - Exhaust apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the maintenance cost and operation cost of a vacuum exhaust system and an exhaust gas treatment system and to also enhance safety by enhancing reaction product removing efficiency by enhancing the scrubbing capacity of a water seal type vacuum pump and enhancing the detoxifying efficiency of harmful reaction gas and also reducing the amt. of dilution gas. SOLUTION: An exhaust apparatus is equipped with a gas-water separation tank 11 attached to a water seal type vacuum pump 10 performing the exhaustion of a reactor used in the production of a semiconductor on the exhaust side thereof to introduce the mixed discharged matter of exhaust gas and seal water from the water seal type vacuum pump 10 and forcibly mixing the exhaust gas 12 and seal water in the mixed discharged matter 14 by the exhaust pressure from the water seal type vacuum pump 10 in a contact state to separate and discharge the exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes an improvement in the scrubber capacity of a water-sealed vacuum pump and an improvement in the reaction product removal efficiency by combining a water-sealed vacuum pump with a steam-water separation tank having a scrubber function. It relates to an exhaust device.

[0002]

2. Description of the Related Art In general, CVD (chemical v)
In the case of performing exhaust gas treatment of a decompression reactor for performing apor deposition, etc., when a water ring vacuum pump is connected to a stage subsequent to a mechanical booster pump or a dry pump to form an exhaust system, the water ring vacuum pump is It is known that it is possible to realize an exhaust gas treatment system having a simple, inexpensive, and highly safe exhaust gas elimination function while functioning as a final-stage vacuum pump constituting a vacuum evacuation system in a reaction chamber in a reduced-pressure reactor. ing.

[0003] An exhaust gas treatment system using this water-sealed vacuum pump is capable of removing various exhaust gases in a decompression reactor, such as an exhaust gas when a thin film is formed by a decompression reactor and an exhaust gas when a reaction chamber is dry-cleaned. It is applicable to the treatment and is considered to be an extremely effective exhaust gas treatment means.

[0004] For example, in an exhaust gas treatment for forming a thin film, for a flammable or explosive gas such as SiH ₄ , a gas containing O ₂ such as air is introduced to introduce SiO ₂ and H _2.
2 O, and can be taken into sealed water in a water-sealed vacuum pump and safely treated (if necessary, see JP-A-55-34158 and JP-A-56-1527).
No., JP-A-59-197141, etc.).

In the treatment of exhaust gas when the reaction chamber is dry-cleaned, a cleaning gas discharged from the reaction chamber and a gasified reaction product are supplied to a water ring vacuum pump made of a corrosion resistant metal. It can be taken in sealed water and subjected to removal treatment (if necessary, see Japanese Patent Application Laid-Open No. 9-157852).
Publication).

In addition, a gas that reacts with water, such as Cl ₂ , F ₂ , HF, or HCl, or a water-soluble gas can be taken into sealed water.

[0007] As described above, the water ring vacuum pump can function as a scrubber for the exhaust gas from the decompression reactor, and removes dangerous and harmful unreacted gas, reaction gas, and reaction products in the exhaust gas. By various actions such as reacting with water or absorbing into water or dissolving in water, taking it into sealed water, treating it into a steam-water separation tank, and separating it into wastewater and exhaust gas. And discharge.

[0008] Due to the scrubber function of the water ring vacuum pump, the exhaust gas from the reduced pressure reactor can be sent to the exhaust duct connected to the collecting scrubber without passing through the dry removal device, and Wastewater can be reused through appropriate water treatment.

Therefore, a water-sealed vacuum pump is used for the vacuum evacuation system, which is indispensable for the vacuum reactor, and by using it, an exhaust gas treatment system that is space-saving, inexpensive, and has low maintenance costs is realized. can do.

By the way, since the exhaust gas from the decompression reactor for performing CVD or the like contains not only the above-mentioned gas but also a reaction product, the inside of the pump or the exhaust gas is evacuated during the evacuation operation. Powdered and deposited in the tube.

For example, a secondary reaction product is generated from a gas such as NH ₄ Cl used to form a nitride film by applying a CVD method, and is powdered during evacuation to form a hard film. Therefore, it is essential to remove, wash and clean it.

[0012] The scrubber function of the water-sealed vacuum pump works effectively on such a reaction product as well, and the reaction product can be dissolved and taken in the sealed water. By installing a water-sealed vacuum pump at the last stage of the exhaust system and acting as an exhaust gas treatment system, powder deposition in the vacuum exhaust system is reduced and maintenance costs are kept low. Can be.

In order to effectively exert the scrubber function of the water ring vacuum pump on the reaction product, the operating temperature of the pump and piping is increased and the amount of diluted N ₂ gas is adjusted. Therefore, it is necessary to guide the reaction product as it is in a gaseous state to a water-sealed vacuum pump to dissolve it in working sealing water and drain it.

By doing so, the reaction product is not generated in the mechanical booster pump, the dry pump, and the piping, and is dissolved in the working sealing water in the water ring vacuum pump. After all, in the evacuation system,
Pulverization and accumulation of the reaction product in the exhaust gas treatment system are suppressed, and the maintenance cycle can be extended.

Incidentally, a water ring vacuum pump is, for example, C
Since the unreacted gas and sealed water in the VD are mixed in the pump body and the mixture is discharged from the same exhaust port, the exhaust port is usually connected to a drainage tank called a steam separator tank. The exhaust gas is separated into exhaust gas and drainage in the tank, and the exhaust gas is discharged from the exhaust port of the steam separator and the drainage is also discharged from the drain port.

As described above, the reaction product contained in the exhaust gas from the reduced-pressure reactor is dissolved in the working sealing water and discharged by the scrubber function in the water ring vacuum pump. Some of them may remain in the exhaust gas, and after entering the steam separator, may be discharged from the exhaust port as exhaust gas to the exhaust duct via the exhaust pipe.

[0017] For this reason, the reaction product becomes powdery and accumulates at the exhaust port of the steam separator and the inner wall of the exhaust pipe, causing a problem that the exhaust path is blocked, so that periodic maintenance work is required. It has become.

[0018]

SUMMARY OF THE INVENTION In the present invention, the scrubber capacity of a water ring vacuum pump is improved to increase the efficiency of removing reaction products, the efficiency of removing harmful reaction gases, and the amount of diluent gas is reduced. The maintenance cost and operation cost of the vacuum exhaust system and the exhaust gas treatment system are reduced, and the safety is also improved.

[0019]

SUMMARY OF THE INVENTION In the present invention, the exhaust gas pressure of a water ring vacuum pump is used to forcibly mix and contact exhaust gas and water seal, and the scrubber function is improved by increasing the contact efficiency. Is the basis.

FIG. 1 is a block diagram showing an exhaust gas treatment system for a CVD apparatus using a water ring vacuum pump for explaining the principle of the present invention.

In the figure, 1 is a reaction chamber, 2 is a SiH ₄ gas source, 3 is a ClF ₃ gas source, 4 and 5 are gas supply pipes,
6 is an exhaust gas exhaust pipe, 7 and 8 are mechanical booster pumps, 9 is an ejector pump, 10 is a water ring vacuum pump, 11 is a steam separation tank having a scrubber function, 12
Is intake gas, 13 is working water, 14 is a mixed discharge of intake gas 12 and sealing water, 15 is exhaust gas from the steam separation tank,
Numeral 16 indicates drainage from the steam separator having a scrubber function.

The above-mentioned intake gas 12 is exhaust gas from the reaction chamber 1 and is particularly called an intake gas in the sense that it is sucked by the water-sealed vacuum pump 10, and the working water 13 is the water-sealed vacuum pump 10. Steam-water separation tank 11 after passing
While inside it will be referred to as sealing.

In the illustrated exhaust gas treatment system, a water-sealed vacuum pump 10 is the last-stage vacuum pump of the vacuum evacuation system, and thereafter a steam / water separation tank 11 is connected, and the steam / water separation tank 11 has a scrubber function. When the mixed effluent 14 of the intake gas 12 and the sealing water is sent, the mixed effluent 1
4 is a water-sealed vacuum pump 1 in the steam separation tank 11.
The exhaust gas pressure from 0 forcibly promotes the mixed contact between the intake gas 12 and the sealed water, thereby increasing the contact efficiency.

According to the experiment, a water ring vacuum pump 10 equipped with the steam-water separation tank 11 having the scrubber function was used.
When operated as a vacuum exhaust system and an exhaust gas treatment system for forming a nitride film, NH ₄ Cl product powder is contained in an exhaust pipe connecting an exhaust port of the steam separator 11 and a duct pipe in 12 months. Although adhesion of about 5 [mm] was observed, this is still in a state of withstanding normal operation, and the cleaning and cleaning period can be greatly extended. Incidentally, when a steam-water separation tank having no scrubber function is used, 20 mm of NH ₄ Cl product powder adheres and accumulates in the exhaust pipe in three months.

Also, in the case where the reaction chamber 1 is dry-cleaned, the steam-water separation tank 11 having a scrubber function is effective. , The concentration of Cl ₂ , F ₂ , HF, HCl, etc. decreased, and the improvement of the abatement efficiency was confirmed.

As described above, in the exhaust device of the present invention, the exhaust device is attached to the exhaust side of a water-sealed vacuum pump (eg, a water-sealed vacuum pump 10) for exhausting a reaction device used for semiconductor manufacturing and the like. A mixed effluent of the exhaust gas from the water-sealed vacuum pump and the sealed water (for example, mixed effluent 14) is introduced, and the exhaust gas and the sealed water in the mixed effluent are discharged by the exhaust pressure of the water-sealed vacuum pump. , And a steam-water separation tank (for example, a steam-water separation tank 11) that separates and discharges after forcibly mixing and contacting.

By employing the above means, when the exhaust system is operated, the scrubber capacity of the water / water separation tank is added to the scrubber capacity of the water ring vacuum pump, so that the efficiency of removing reaction products is greatly improved. In addition, the exhaust gas abatement capacity is improved, so that the amount of diluent gas can be reduced, so that the maintenance cost and operation cost of the vacuum exhaust system and the exhaust gas treatment system are reduced, and safety is improved.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a cutaway view of a main part of a steam / water separation tank having a scrubber function according to the present invention.
The same symbols as those used in FIG. 1 represent the same parts or have the same meaning. It should be noted that the drawing also shows a water ring vacuum pump.

In the drawing, 17 is a pump exhaust port, 21 is a mixing contact chamber, 22 is a water storage chamber, 23 is a separation chamber, 24 is an exhaust pipe, 25 is an inlet pipe, 26 is an inner wall of a tank, and 27 is a partition plate. , 29 are gutters having a rectangular cross section, 36 is a drain port, 38
Is exhaust gas, 39 is a baffle, 40 is a tank exhaust port, 42
Is a drain valve, 43 is a connecting pipe, 44 is a pressure gauge, 45 is a conical bottom plate, and 46 is stored water.

The steam / water separation tank 1 having this scrubber function
1 is roughly divided into a mixing contact chamber 21 in an intermediate part, a water storage chamber 22 in a lower part, and a separation chamber 23 in an upper part. In the center of the mixing contact chamber 21 in the intermediate part, Water storage room 2
An exhaust pipe 24 is provided from 2 to the separation chamber 23, and reaches the conical bottom plate 45 of the separation chamber 23.

In the water / water separation tank 11, the intake gas 12 sucked by the water-sealed vacuum pump 10 and the supplied working water 13 are mixed in the water-sealed vacuum pump 10 during the intake and exhaust operations. Then, the mixture is discharged from the exhaust port 17 as the mixed discharge 14, and is fed into the mixing contact chamber 21 through the introduction pipe 25.

FIG. 3 is a plan view of an essential part of the water / water separation tank cut along the line XX in FIG. 2 and viewed in the direction of the arrow, and the same symbols as those used in FIG. Parts or have the same meaning.

FIG. 3 clarifies the structure of the inlet pipe 25. The inlet pipe 25 is provided tangentially along the inner wall 26 of the circular tank, and is provided with the intake gas 12 discharged from the water ring vacuum pump 10. The mixed effluent 14 and the sealing water flow down while rotating along the inner wall 26 of the tank.

FIG. 4 is a cut-away side view of a main part for clarifying the structure inside the steam separator, particularly near the partition plate.
The same symbols as those used in FIGS. 2 and 3 represent the same parts or have the same meaning.

In the drawing, 28 is a porous portion of the partition plate 27, 30 is an inner edge of the gutter 29, 31 is water sealing, 32
Denotes a water film of the sealing water 31, 33 denotes a spray, 34 and 35 denote partition plates, 47 denotes a gutter of the partition plate 34, 48 denotes a gutter of the partition plate 35, and 49 denotes a water surface. In addition, sealing water 31
Is originally water in the mixed effluent 14, and contains a part of exhaust gas.

As is apparent from the figure, a porous portion 2 having a fixed width and a large number of small holes is provided below the mixing contact chamber 21.
There are provided a partition plate 27 composed of the pipe 8 and the gutter 29, and three layers of partition plates 34 and 35 having the same structure, and are partitioned from the water storage chamber 22. Note that only the partition plate 34 is composed of only the porous portion and the large gutter 47.

Out of the three partition plates, the gutter 29 of the uppermost partition plate 27 is provided on the entire circumference along the inner wall 26 of the tank.
It is designed to store as.

The gutter 29 has an appropriate width and volume, and is horizontal, so that the sealed water 31 filled with water in the gutter 29 overflows the inner edge 30. Further, since the porous portion 28 is configured to adjust the closing rate with respect to the amount of water to limit the amount of flow, the partition plate 27
A water film 32 having a certain thickness is formed on the upper surface.

Since the water ring vacuum pump 10 has an exhaust pressure, the water film 32 is also applied with pressure, and the partition plate 27
The droplets of the sealed water 31 and the exhaust gas are both scattered and sprayed from the porous portion 28, and the spraying is indicated by a symbol 33 in the figure.

As shown, the three-layer partition plate 2
7, 34, and 35 are configured such that the position of each gutter and the position of the perforated portion are switched, so that the spray 33 from the upper perforated portion is received by the lower gutter, and when the gutter becomes full. It overflows into the porous part and is sprayed to the lower gutter.

As described above, for example, in the process in which the exhaust gas passes through the water film 32 and is sprayed together with the sealing water 31 and the like at the porous portion 28 of the partition plate 27 and sprayed onto the lower water surface 49,
The contact efficiency between the exhaust gas and the sealed water increases, and the reaction, absorption, and dissolution of the exhaust gas and the sealed water are performed efficiently.Hazardous substances in the exhaust gas are trapped in the sealed water. The efficiency of harm is improved.

The sealed water that has passed through the three-layered partition plates 27, 34, and 35 accumulates in the water storage chamber 22 to become the stored sealed water 46. When the stored sealed water 46 exceeds the height of the drain port 36, the drain water 16 is discharged.
The exhaust gas 38 containing the droplets of the sealed water 31 is discharged from the tank at a reduced flow velocity in the water storage chamber 22, moves while separating and dropping the droplets, and rises from the central exhaust pipe 24 to be separated from the separation chamber. It is led to 23.

Since the separation chamber 23 is a large space, the flow rate of the exhaust gas 38 is further reduced to separate and remove the water-sealed droplets, and the exhaust gas is discharged from the exhaust port 40 to the outside of the tank as the exhaust gas 15.

Although water droplets are aggregated in the baffle 39 and the separation chamber 23, they flow down from the conical bottom plate 45 along the wall surface of the exhaust pipe 24 and return to the water storage chamber 22.

The solid powder such as dust mixed in the mixed effluent 14 is dispersed without being dissolved in the sealing water 31, but the sealing water 31 flows down to the water storage chamber 22 and the stored sealing water 4.
6 and a part thereof is discharged out of the tank together with the drainage 16.

However, since solid powder or the like may accumulate on the bottom of the water storage chamber 22, it may be discharged through the drain valve 42 in such a case.

The mixing contact chamber 21 and the water storage chamber 22 are connected by an external communication pipe 43, and the stored sealing water 46 of the water storage chamber 22 enters the communication pipe 43.
Is not distributed, but the partition plates 27, 3
When the pressure in the mixing contact chamber 21 rises due to clogging of the porous portion at 4, 35 or the like, the connecting pipe 43
Exhaust gas 38 escapes via this to maintain safety. The pressure increase in the mixing contact chamber 21 can be confirmed by the pressure gauge 44.

[0048]

The exhaust device according to the present invention is mounted on the exhaust side of a water ring vacuum pump for exhausting a reactor used for manufacturing semiconductors and the like, and is sealed with exhaust gas from the water ring vacuum pump. A steam-water separation tank for introducing mixed discharge with water and forcibly mixing and contacting exhaust gas and sealed water in the mixed discharge with exhaust pressure from the water-sealed vacuum pump, and separating and discharging the separated water. Is provided.

By employing the above configuration, when the exhaust system is operated, the scrubber capacity of the water / water separation tank is added to the scrubber capacity of the water ring vacuum pump, so that the efficiency of removing reaction products is greatly improved. In addition, the exhaust gas abatement capacity is improved, so that the amount of diluent gas can be reduced, so that the maintenance cost and operation cost of the vacuum exhaust system and the exhaust gas processing system can be reduced, and the safety is improved. I do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an exhaust gas treatment system for a CVD apparatus using a water-sealed vacuum pump for explaining the principle of the present invention.

FIG. 2 is a fragmentary explanatory view showing a steam-water separation tank having a scrubber function in the present invention.

FIG. 3 is a plan view of an essential part of the steam separator, taken along line XX in FIG. 2 and viewed in the direction of the arrow.

FIG. 4 is a cutaway side view of an essential part for clarifying a structure inside the steam separator, particularly near a partition plate.

[Description of Signs] 1 Reaction chamber 2 SiH ₄ gas source 3 ClF ₃ gas source 4 and 5 Gas supply pipe 6 Exhaust gas exhaust pipe 7 and 8 Mechanical booster pump 9 Ejector pump 10 Water ring vacuum pump 11 Scrubber function Steam-water separation tank with 12 Inlet gas 13 Working water 14 Mixture discharge of intake gas 12 and sealing water 15 Exhaust gas from steam-water separation tank 16 Drainage from steam-water separation tank with scrubber function

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinji Kikuchi 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Kei Omatsu 30 Miyakecho, Moriyama-shi, Shiga Shinko Seiki Intra-company F term (reference) 3H029 AA07 AA17 AB06 BB34 BB35 BB36 BB37 BB41 BB47 CC22 CC23 CC25 CC42 4D002 AA18 AA19 AA22 AA23 AA26 BA02 BA14 CA03 CA20 DA35 EA05 EA13 GA03 GB04 HA02

Claims (1)

[Claims] 1. A water-sealed vacuum pump attached to the exhaust side of a water-sealed vacuum pump for evacuating a reactor, introducing a mixed discharge of exhaust gas and sealed water from the water-sealed vacuum pump and introducing the water-sealed vacuum pump. An exhaust device comprising a steam-water separation tank for forcibly mixing and contacting the exhaust gas and the sealed water in the mixed effluent with the exhaust pressure from the tank and separating and discharging the exhaust gas.