JP2001025633A - Method and apparatus for detoxifying exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate trouble such as equipment stop loss or the like while holding a beneficial point of a wet method by eliminating the deposition of a solid substance at a gas-liquid contact place while keeping gas-liquid contact efficiency high. SOLUTION: A solvent 5 (oil, fluorine type inert liquid) solubilizing a substance to be detoxified (SiHCl3) by the gas-liquid contact with exhaust gas 4 (SiHCl3, HCl, H2) and not forming a harmless solid substance (SiO2) is prepared. The solvent 5 and the exhaust gas 4 are brought to a gas-liquid contact state in an absorbing apparatus 2 to form a soln. 5' of a substance to be detoxified (solvent 5 having absorbed SiHCl3). In a reaction apparatus, the formed soln. 5' of the substance to be detoxified (solvent 5 having adsorbed SiHCl3) and a specific liquid (H2O) are reacted (SiHCl3+2H2O→3HCl+SiO2+H2) to form a harmless solid substance (SiO2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas elimination method and apparatus, and more particularly to harmless exhaust gas such as silicon chloride used in the treatment of silicon wafers, which is discharged as harmless solid substances. The present invention relates to an abatement method or abatement device.

[0002]

2. Description of the Related Art A semiconductor device is manufactured by epitaxially growing a thin film on a surface of a semiconductor substrate.

That is, a silicon substrate is generally used as a semiconductor substrate. As a raw material gas for the thin film, for example, Si
HCl3 (trichlorosilane) is used.

In a reaction furnace, SiHCl 3 is supplied to the surface of a silicon substrate. The same silicon thin film is formed by epitaxial growth on the surface of the silicon substrate by the chemical reaction of SiHCl3. For example, a predetermined concentration of boron B is added to the epitaxial growth layer as an impurity. Boron B is doped into the epitaxially grown layer during the epitaxial growth process, for example, by supplying a predetermined concentration of a doping gas B2H6 into the furnace.
Thus, an epitaxially grown layer to which a predetermined concentration of impurity B is added is formed on the surface of the silicon substrate.

[0005] Epitaxial growth is performed in a growth furnace as follows.

[0006] A growth gas is supplied into the epitaxial growth furnace via a gas supply path. A growth gas comprising a source gas (SiHCl3), a doping gas (B2H6) and a carrier gas (H2) is supplied from a gas supply source into the epitaxial growth furnace.

[0007] The epitaxial growth furnace is provided with a discharge port for exhausting gas in the furnace to the outside.

When a growth gas is supplied to the epitaxial growth furnace, the growth gas passes over the surface of the wafer substrate.
The wafer substrate is held by a susceptor. A chemical reaction in a high temperature gas phase (1000 ° C. to 1200 ° C.) is performed on the substrate, and an impurity (B) is implanted into the surface of the substrate at a predetermined concentration to form a thin film. The growth gas that has not contributed to the chemical reaction in the high-temperature gas phase, the by-product gas that has undergone the chemical reaction but has not contributed to the epitaxial growth, etc. are exhausted from the outlet.

The susceptor is made of SiC or the like. Therefore, when the source gas passes over the susceptor, unnecessary silicon is deposited. Therefore, an etching gas is supplied into the epitaxial growth furnace through a gas supply path in order to remove the deposited silicon. HCl as an etching gas and a carrier gas (H2) for diluting the HCl are supplied from a gas supply source. Here, the etching gas may be a pure gas of hydrogen chloride gas or a mixed gas containing hydrogen chloride gas.

[0010] When the etching gas is supplied into the epitaxial growth furnace, the etching gas passes through the surface of the susceptor. As a result, unnecessary silicon deposited on the susceptor reacts chemically with the etching gas (Si (s) + 2HCl).
(g) → SiCl 2 (g) + H 2 (g)) and decomposed. Part of the etching gas that has contributed to the etching is exhausted from the exhaust port to the outside. Several tens of percent of the gas input to the epitaxial growth furnace is exhausted as exhaust gas.

The gases SiHCl3, B2H6, H2, HCl and the like discharged from the outlet of the epitaxial growth furnace are supplied to the detoxifier. After being formed into harmless substances by abatement equipment, they are released to the atmosphere.

In particular, if silicon chloride such as SiHCl3 or hydrogen chloride HCl is released to the atmosphere as it is, it will adversely affect the human body and the like, and must be converted into harmless substances. HCl gas is corrosive and adversely affects equipment.

[0013] Therefore, the following methods have been conventionally attempted as abatement methods.

1) Adsorption method This is a method in which harmful substances in exhaust gas are adsorbed by an adsorbent, and the remaining harmless exhaust gas is released into the atmosphere.

2) Combustion method Harmless SiO 2 and hydrogen chloride gas are generated by burning unreacted gas containing silicon (SiHCl 3 + O 2).
(→ SiO 2 + 3HCl + H 2 O), and furthermore, after removing SiO 2 and neutralizing the hydrogen chloride gas (harmless by the wet method of the following item 3)), harmless exhaust gas is discharged into the atmosphere. The hydride (B2H6) as a dopant is also rendered harmless by combustion.

3) Wet method 3-a) Method using a leak-type scrubber An aqueous caustic soda solution (NaOHaq) is used as an abatement agent. An aqueous solution of caustic soda is pumped from the tank by a pump and supplied to the upper side of the leak shelf. The aqueous solution of caustic soda falls under the leak shelf through the hole of the leak shelf. The exhaust gas is supplied there. As a result, the exhaust gas and the aqueous solution of caustic soda are brought into gas-liquid contact to form a harmless solid substance (hydrate of SiO 2) by the following reaction formula (1) and neutralize hydrogen chloride gas by the following reaction formula (2) Harmed by The hydrate of SiO2 is dissolved in the aqueous solution of caustic soda and collected and removed together with the aqueous solution of caustic soda.

SiHCl3 + 2H2O → 3HCl + SiO2 + H2 (1) HCl + NaOH → NaCl + H2O (2) 3-b) Method Using Jet Scrubber A caustic soda aqueous solution (NaOHaq) is used as a harm-removing agent. As shown in FIG. 2, a caustic soda aqueous solution 40 is sucked up from a tank by a pump and supplied to an upstream side of a jet nozzle 6 c provided in the chamber 6. On the other hand, exhaust gas is supplied to the upstream side of the nozzle 6c. As a result, the caustic soda aqueous solution 40 having a high flow rate and the exhaust gas are brought into gas-liquid contact in the nozzle 6c to form a harmless solid substance (hydrate of SiO 2) by the above reaction formula (1), and the above reaction formula (2) Hydrogen chloride gas is removed by neutralization. The SiO2 hydrate is dissolved in the aqueous caustic soda solution 40 and jetted from the nozzle 6c as a jet stream. The SiO2 hydrate is recovered and removed together with the aqueous caustic soda solution 40.

However, the adsorption method 1) requires an adsorbent. For this reason, the problem that running cost becomes large arises.

In the combustion method 2), a process for separately removing SiO2 generated by combustion is required, and a process for separately removing and harming hydrogen chloride gas generated by combustion is required.

In the above-mentioned 3-a) "method using a leaky scrubber", since the exhaust gas is supplied to the aqueous solution of caustic soda which has fallen from the leaky shelf, the efficiency of gas-liquid contact between the exhaust gas and the aqueous solution of caustic soda is increased. Is low. In other words, the abatement efficiency is low. Therefore, it is necessary to increase the size of the scrubber in order to increase the abatement efficiency.

Therefore, there is no disadvantage in these abatement methods.
b) “Method using a jet scrubber” has been widely adopted in recent years.

"Elimination method using jet scrubber"
According to the method, there is no problem that the running cost is increased because the adsorbent is not used. Further, SiO2 hydrate is dissolved in the aqueous caustic soda solution 40 and the aqueous caustic soda solution 4
Since it is collected and removed together with 0, there is no problem that a separate removal process is required.

Further, since the exhaust gas is brought into gas-liquid contact with the caustic soda aqueous solution 40 having a fast flow in the nozzle,
The efficiency of gas-liquid contact between the exhaust gas and the aqueous caustic soda solution 40 is increased as compared with the “method using a leaky rack type scrubber” of 3-a). That is, the abatement efficiency increases. Therefore, an excellent effect is obtained that it is not necessary to increase the size of the scrubber in order to enhance the abatement efficiency.

[0024]

However, in the "method using a jet scrubber" of 3-b), as shown in FIG. 2, the mist and the mist are generated by the rapid flow of the aqueous solution of caustic soda 40 on the inner wall 6b of the chamber near the outlet of the nozzle 6c. Water vapor 41 is generated. Therefore, before the exhaust gas comes into gas-liquid contact with the main stream of the aqueous caustic soda solution 40, a part of the exhaust gas comes into contact with the mist and water vapor 41, thereby generating a solid SiO 2 hydrate 42 on the inner wall 6 b of the chamber 6.

The solid SiO 2 hydrate 42 grows as the harm removal time elapses and is deposited on the inner wall 6b of the chamber. As a result, the solid SiO2 hydrate 42 reaches the nozzle 6c and eventually blocks the exhaust gas passage.

Therefore, conventionally, a gas curtain is formed by dry nitrogen so that the exhaust gas does not come into direct contact with the mist and water vapor 41 to prevent the deposition of solid SiO2 hydrate 42 on the nozzle tip and the chamber wall 6b. ing. However, this method complicates the configuration of the device and increases the running cost.

[0027] Even if such a measure is taken against the deposit, it is impossible to prevent the deposit from being generated at all. Therefore, the solid Si deposited on the chamber inner wall 6b
O2 hydrate 42 is periodically cleaned and removed. However, every time the scrubber is cleaned, a loss occurs due to the stoppage of the equipment.

The present invention has been made in view of such circumstances, and eliminates the accumulation of solid substances at places where gas-liquid contact is made while maintaining high gas-liquid contact efficiency. It is an object of the present invention to eliminate problems such as equipment stoppage loss while maintaining the above.

[0029]

Means and Effects for Solving the Problems The first aspect of the present invention.
The present invention is a method for removing a harmful substance in a flue gas by reacting a harmful harmful substance in a flue gas with a specific liquid to generate a harmless solid substance, thereby removing the harmful substance.
By preparing a solvent that dissolves the harmless substance by gas-liquid contact with the exhaust gas and does not generate the harmless solid substance, and brings the solvent and the exhaust gas into gas-liquid contact, the harmful substance is removed. And a step of generating the harmless solid substance by reacting the generated solution of the harmful substance with the specific liquid.

The first invention will be described with reference to FIG.

According to the first invention, the exhaust gas 4 (SiHCl
3. Solvent 5 (oil) that dissolves harmful substances (SiHCl3, HCl and other chlorides) by gas-liquid contact with HCl and other chlorides, H2, and does not generate harmless solid substance 42 (SiO2). , A fluorine-based inert liquid). Then, in the absorption device 2, the solvent 5 and the exhaust gas 4 are brought into gas-liquid contact, and a solution 5 'of the harmful substance (the solvent 5 which has absorbed chloride such as SiHCl3) is generated.

Then, in the reaction device 3, the solution 5 '(solvent 5 having absorbed chloride such as SiHCl3) formed above and a specific liquid (a scavenger: H2O) react with each other (SiHCl3 + 2H2O). → 3HCl + SiO2 + H2)
By doing so, a harmless solid substance 42 (SiO2) is generated.

As described above, according to the first invention, the absorbing device 2
The exhaust gas 4 is brought into gas-liquid contact with the solvent 5 in the chamber 6 to generate a solution 5 ′ that absorbs the harmful substances (chlorides such as SiHCl 3) without generating harmless solid substances 42. The detoxification is performed by reacting the liquids (solution 5 'and H2O) at a place different from the chamber 6. For this reason, the solid substance 42 (SiO2) can be reliably removed without accumulating at the gas-liquid contact location (in the chamber 6).

As described above, according to the first aspect of the present invention, it is possible to eliminate the accumulation of the solid substance at the place where the gas-liquid contact is made while maintaining the high efficiency of the gas-liquid contact. In addition, troubles such as equipment stop loss can be eliminated.

According to the second invention, in the first invention, the harmful substance to be harmed is silicon chloride, the specific liquid is water (H 2 O) or an aqueous solution of caustic soda (NaOHaq), and the harmless solid substance 42 is It is characterized by being silicon oxide (SiO2).

In a third aspect based on the first aspect, the solvent is an oil or a fluorine-based inert liquid.

Further, the fourth invention is a method for removing exhaust gas, which removes the harmful substances by reacting the harmful substances in the exhaust gas with a specific liquid to produce a harmless solid substance. In the harm device, a solvent that dissolves the harmless substance by gas-liquid contact with the exhaust gas and does not generate the harmless solid substance is prepared, and the solvent is brought into gas-liquid contact with the exhaust gas, A solution generating means for generating a solution of the harmful substance, and a solid substance generating means for generating the harmless solid substance by reacting the generated solution of the harmful substance with the specific liquid. It is characterized by having.

In the fourth invention, the invention of the method of the first invention is replaced with the invention of the apparatus.

According to a fifth aspect of the present invention, in the fourth aspect, the solution generating means brings the solvent and the exhaust gas into gas-liquid contact in a chamber, and the solution of the harmful substance is discharged from an outlet of a nozzle in the chamber. It is characterized by the fact that it spouts.

In the fifth invention, as shown in FIG. 1, a chamber 6 and a nozzle 6c in the chamber 6 are used as the solution generating means 2, and the solvent 5 and the exhaust gas 4 are brought into gas-liquid contact in the chamber 6, Since the solution 5 'of the harmful substance is ejected from the outlet of the nozzle 6c in the chamber 6, the efficiency of gas-liquid contact can be maintained at a high level. Therefore, the harmful substances can be efficiently absorbed, and the harm can be efficiently performed.

[0041]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an exhaust gas elimination method and apparatus according to the present invention.

FIG. 1 is a diagram showing the configuration of an exhaust gas treatment apparatus 1 according to the embodiment.

In the pre-process of the exhaust gas treatment apparatus 1, an epitaxial growth step of epitaxially growing a silicon thin film on a silicon substrate is performed in an epitaxial growth furnace.

The epitaxial growth is performed by using a raw material gas SiCl 4,
Although it depends on SiHCl3, SiH2Cl2 and SiH4, the reaction is carried out by the following reaction.

(A) SiCl4 + 2H2 → Si + 4HCl (hydrogen reduction reaction) (3) (b) SiHCl3 + H2 → Si + 3HCl (hydrogen reduction reaction) (4) (c) SiH2Cl2 → Si + 2HCl (thermal decomposition reaction) (5) (d) ) SiH4 → Si + 2H2 (thermal decomposition reaction) (6) As a raw material gas for the silicon thin film, for example, SiH of (b)
Cl3 (trichlorosilane) is used. SiHCl3 is supplied to the surface of the silicon substrate in the reactor. The same silicon thin film is formed by epitaxial growth on the surface of the silicon substrate by the chemical reaction of SiHCl3. For example, a predetermined concentration of boron B is added to the epitaxial growth layer as an impurity. Boron B is doped into the epitaxially grown layer during the epitaxial growth process, for example, by supplying a predetermined concentration of a doping gas B2H6 into the furnace. Thus, an epitaxially grown layer to which a predetermined concentration of impurity B is added is formed on the surface of the silicon substrate.

That is, a growth gas is supplied into the epitaxial growth furnace via a gas supply path. Source gas (SiHCl3) and doping gas (B2H)
6) A growth gas comprising a carrier gas (H2) is supplied into the epitaxial growth furnace.

The epitaxial growth furnace is provided with a discharge port for exhausting gas inside the furnace to the outside.

When a growth gas is supplied to the epitaxial growth furnace, the growth gas passes over the surface of the wafer substrate.
The wafer substrate is held by a susceptor. A chemical reaction in a high temperature gas phase (1000 ° C. to 1200 ° C.) is performed on the substrate, and an impurity (B) is implanted into the surface of the substrate at a predetermined concentration to form a thin film. Part of the growth gas that has contributed to the chemical reaction in the high-temperature gas phase is discharged to the outside through the discharge port.

The susceptor is made of SiC or the like. Therefore, when the source gas passes over the susceptor, unnecessary silicon is deposited. Therefore, an etching gas is supplied into the epitaxial growth furnace through a gas supply path in order to remove the deposited silicon. HCl as an etching gas and a carrier gas (H2) for diluting the HCl are supplied from a gas supply source. Here, the etching gas may be a pure gas of hydrogen chloride gas or a mixed gas containing hydrogen chloride gas.

When the etching gas is supplied into the epitaxial growth furnace, the etching gas passes through the surface of the susceptor. As a result, unnecessary silicon deposited on the susceptor reacts chemically with the etching gas (Si (s) + 2HCl).
(g) → SiCl 2 (g) + H 2 (g)) and decomposed. Part of the etching gas that has contributed to the etching is exhausted from the exhaust port to the outside. Several tens of percent of the gas input to the epitaxial growth furnace is exhausted as exhaust gas.

The exhaust gas 4 thus discharged from the outlet of the epitaxial growth furnace, ie, SiHCl3, B2H6, H
2. HCl is supplied to the exhaust gas treatment apparatus 1 of FIG.

However, even if SiHCl 3 is used as a source gas, HCl or S
It contains not only iHCl3 but also SiH2Cl2.

Similarly, when SiCl4 of (a) is used as a raw material gas, HCl or S
Not only iCl4 but also SiHCl3 and SiH2Cl2 are included.

That is, the reaction formula (SiCl4 +) of the above (3)
(2H2 → Si + 4HCl) can be expressed exactly as follows.

SiCl 4 + H 2 ⇔SiCl 2 + 2HCl (7) SiCl 2 + H 2 ⇔Si + 2HCl (8) Here, the intermediate SiCl 2 reversibly reacts with the surrounding HCl and H 2.

SiCl 2 + HCl⇔SiHCl 3 (9) SiCl 2 + H 2 iSiH 2 Cl 2 (10) Therefore, in addition to H 2 and HCl, not only SiCl 4 but also SiHCl 3 and SiH 2 Cl 2 are present in the exhaust gas.

When SiHCl3 is used as a raw material gas, not only HCl but also SiH2C
l2 and the like exist.

However, in the present embodiment, for convenience of explanation, the description will be made on the assumption that only SiHCl3 is present as silicon chloride in the exhaust gas 4 when SiHCl3 is used as a source gas.

Here, silicon chloride such as SiHCl 3,
Hydrochloric acid HCl, if released to the atmosphere as it is, has a bad effect on the human body and the like, and must be converted into a harmless substance. HCl gas is corrosive and adversely affects equipment. For this reason, these gases are harmed by the exhaust gas treatment apparatus 1 of FIG.

The exhaust gas treatment apparatus 1 shown in FIG. 1 is mainly composed of a nozzle 6 c and an absorption apparatus 2 for absorbing SiHCl 3 as silicon chloride in the exhaust gas 4 into a solvent 5.
And silicon chloride SiHCl3 by the absorption device 2.
Reactor 3 for producing harmless solid substance 42 (SiO 2) by reacting solvent 5 absorbing water with water H 2 O
Consists of A wet scrubber 31 for neutralizing and harming the hydrogen chloride gas obtained in the absorption device 2; and a neutralizing agent for neutralizing and harming the hydrogen chloride obtained in the reaction device 3 or an acid containing hydrogen chloride dissolved therein. And a neutralization / recovery device 35 for recovering the solvent 5 while concentrating and recovering the water in hydrochloric acid.

The absorption device 2, the reaction device 3, the wet scrubber 31, and the neutralization / recovery device 35 are connected by various pipes.

In the present embodiment, an oil or a fluorine-based inert liquid is used as the solvent 5. As the fluorinated inert liquid, those commercially available under the registered trademarks "Florinert" and "GALDEN" can be used.

The necessary conditions for the solvent 5 are that the gas and liquid contact with the exhaust gas 4 dissolves silicon chloride (SiHCl 3) and does not produce a harmless solid substance 42 (SiO 2). Specifically, 1) it must be a liquid that does not contain any water. 2) it must be soluble in silicon chloride. 3) it must not react with water. 4) it must be a substance that is insoluble in water. Furthermore, 5) low vapor pressure 6) not ozone depleting substance 7) non-flammable 8) it is desirable to be inexpensive. The condition 5) that the vapor pressure is low is that if the vapor pressure is high, it is scattered and the efficiency of gas-liquid contact is not good. The condition of 6) that the substance is not an ozone depleting substance is environmentally friendly.

Hereinafter, the processing performed in the exhaust gas processing apparatus 1 of FIG. 1 will be described.

As the absorbing device 2, the same device as the conventional jet scrubber is used.

That is, the solvent 5 is stored as an absorbent in the tank 9 below the absorbing device 2. A jet nozzle 6c is provided in the chamber 6. The solvent 5 is sucked up by the pump 11 and supplied into the jet nozzle 6c from the supply port 8 upstream of the jet nozzle 6c.

The solvent 5 is sucked up by the pump 11 through the pipes 10a, 10b and 10c as shown by the arrow A. A flow meter 13 that measures the flow rate of the solvent 5 passing through the pipes 10a, 10b, and 10c is provided on the pipe 10b. Also, the pipelines 10a, 10a
A valve 12 for controlling the flow rate of the solvent 5 passing through b and 10c is provided. The flow rate of the solvent 5 is measured by the flow meter 13 and the valve 12 is determined based on the measurement result.
Is controlled, and the supply amount of the solvent 5 to the nozzle 6c is controlled to the target value. Then, the solvent 5 is jetted from the jet nozzle 6c.

On the other hand, an inlet 7 into which the exhaust gas 4 is introduced is provided upstream of the chamber 6.

The exhaust gas 4 discharged from the epitaxial growth furnace is introduced upstream of the chamber 6 from the inlet 7.

Therefore, the solvent 5 and the exhaust gas 4 respectively supplied from the upstream of the nozzle 6c and the chamber 6 form a high-speed flow near the jet port of the nozzle 6c in the chamber 6 and come into gas-liquid contact. Then, a jet stream is ejected from the outlet of the nozzle 6c. Therefore, gas-liquid contact between the solvent 5 and the exhaust gas 4 is performed very efficiently.

In this way, the solvent 5 and the exhaust gas 4 are brought into gas-liquid contact, and the solvent 5 absorbing SiHCl 3, that is, the solution 5 ′
Is generated. Here, since there is no moisture in the gas-liquid contact portion, no solid substance such as SiO2. (NH2O) is generated. The solution 5 'is stored in the lower layer 9b of the tank 9. HCl in the exhaust gas 4 is slightly absorbed by the solvent 5 and taken into the solution 5 '.

Further, H2 and HCl gases are ejected from the nozzle 6c. These H2 and HCl gases are stored in the upper layer 9a of the tank 9. The upper layer 9a contains some SiHCl3 gas not absorbed by the solvent 5.

The upper layer 9a of the tank 9 and the wet scrubber 31 are communicated by pipes 28 and 30.

In the wet scrubber 31, an aqueous caustic soda solution (NaOHaq) is used as a harm-removing agent. In the wet scrubber 31, the same detoxification processing as described above with reference to FIG. 2 is performed.

That is, the above-mentioned H2, HC
1 gas is supplied to the wet scrubber 31. Then, the aqueous caustic soda solution 40 is brought into gas-liquid contact with H2 and HCl gas, and the reaction of the above formula (2) is performed (HCl + NaOH → NaCl + H2O).
Hydrogen chloride gas is removed by neutralization. Note that S
A slight amount of iHCl3 gas is present, and the reaction (SiHCl3 + 2H2O → 3HCl + SiO2 + H2) of the above formula (1) produces a harmless solid substance 42 (a hydrate of SiO2). Does not occur. Some SiO2 hydrate is dissolved in the aqueous sodium hydroxide solution 40, and is recovered and removed together with the aqueous sodium hydroxide solution 40.

The lower layer 9b of the tank 9 of the absorber 2 and the reactor 3 are communicated with each other by pipes 14a, 14b and 20. The lower layer 9b of the tank 9 is provided with pipes 14a, 14b,
14c.

A pump 15 for drawing the solution 5 'of the lower layer 9b of the tank 9 into the pipe 14a is provided on the pipe 14a. A flow meter 19 for measuring the flow rate of the solution 5 ′ supplied to the reactor 3 through the pipes 14 a and 20 is provided on the pipe 20. A valve 18 for controlling the flow rate of the solution 5 ′ supplied to the reactor 3 through the pipes 14 a and 20 is provided on the pipe 20. The flow rate of the solution 5 'is measured by the flow meter 19, and the valve 18 is controlled based on the measurement result to control the solution 5'.
Is controlled to the target value.

The pipelines 14a, 14b, 1
A flow meter 17 is provided for measuring the flow rate of the solution 5 'passing through 4c and flowing back to the lower layer 9b of the tank 9. The pipes 14a, 14b, 14c are provided on the pipe 14c.
Is provided with a valve 16 for controlling the flow rate of the solution 5 'passing through the lower layer 9b of the tank 9 and flowing back. The flow rate at which the solution 5 'recirculates is measured by the flow meter 17, and the valve 16 is controlled based on the measurement result, and the return amount of the solution 5' to the tank lower layer 9b is controlled to a target value.

Accordingly, the solution 5 ′ in which SiHCl 3 has been taken in is supplied from the lower layer 9 b of the tank 9 to the reactor 3 via the pipes 14 a and 20 in order to regenerate the original solvent 5.
Here, there is a limit in the ability of the reactor 3 to regenerate the solution 5 'into the solvent 5. Therefore, a part of the solution 5 'in the lower layer 9b of the tank 9 is returned to the tank lower layer 9b by circulating through the pipes 14a, 14b and 14c.

Next, the processing in the reactor 3 will be described.

The reaction apparatus 3 is configured around a stirrer 21. In this embodiment, water H2O is used as the abatement agent.

Replenishing water H 2 O is supplied to the stirrer 21 via the pipes 36a and 36b. Line 3 is connected to line 36a.
A flow meter 37 for measuring the flow rate of water H2O passing through 6a and 36b is provided. The supply flow rate of water H2O supplied to the stirrer 21 is controlled based on the flow rate measured by the flow meter 37.

The replenishing solvent 5 is stored in the tank 22. The solvent 5 drops from the lower outlet of the tank 22 and is supplied into the agitator 21 via the pipe 38.

In the stirrer 21, the solution 5 ′ supplied through the line 20 and the water H 2 supplied through the line 36 b
And O are stirred. When the solution 5 'and water are stirred, nitrogen gas may be brought into contact with the liquid to emulsify it to promote the reaction of the above formula (1).

As a result, the SiHC dissolved in the solvent 5
l3 reacts with H2O. The reaction formula is the above formula (1) (SiH
Cl3 + 2H2O → 3HCl + SiO2 + H2). By the reaction of the above formula (1), water H 2 O, solvent 5, Si
O 2 hydrate SiO 2 · (nH 2 O) is separated in the stirrer 21.

The harmless solid substance 42 (SiO 2.
(NH2O)) precipitates on the lowermost layer 21d of the stirrer 21. The solvent 5 is stored in the upper layer 21c of the lowermost layer 21d (when a fluorine-based inert liquid is used as the solvent 5). HCl is generated by the reaction of the above formula (1). The HCl-containing water H 2 O (acidic water) is
c is stored in the upper layer 21b. The H2 and HCl gases generated by the reaction of the above formula (1) are stored in the layer 21a above the layer 21b.

When SiH 2 Cl 2 is used instead of SiHCl 3 as a raw material gas, the following reaction (11) is carried out instead of the above (1).

SiH 2 Cl 2 + 2H 2 O → 2HCl + SiO 2 + 2H 2 (11) The outlet of the lowermost layer 21 d of the stirrer 21 and the upper layer 21 thereof
The inflow ports of the pipes c are pipes 23a, 23b, 23c, 23d,
It is communicated by 23g.

The lowermost layer 21 of the stirrer 21 is provided on the pipe 23a.
A pump 39 is provided for drawing d2 SiO2. (nH2O) into the pipeline 23a. Filters 23 for recovering SiO2. (NH2O) are provided on the pipes 23c and 23d, respectively.
e, 23f are provided.

For this reason, the pipes 23a, 23b, 23c, 2
The solvent 5 and SiO 2 · (nH 2 O) pass through 3d, and the harmless solid substance 42 (SiO 2 · (n
H2O)) is recovered. The solvent 5 that has passed through the filters 23e and 23f flows into the storage layer 21c of the solvent 5 of the stirrer 21 via the pipes 23c, 23d, and 23g.

The solvent storage layer 21c of the stirrer 21 and the nozzle 6
c is connected to the supply port 8 by conduits 24a, 24b, and 10c. A pump 25 for drawing the solvent 5 in the solvent storage layer 21c of the stirrer 21 into the pipe 24a is provided on the pipe 24a.
Is provided. On the pipe 24b, the pipe 24a,
A flow meter 27 for measuring the flow rate of the solvent 5 supplied to the supply port 8 of the nozzle 6c after passing through 24b and 10c is provided. On the pipe 24b, the pipes 24a, 24b,
A valve 26 for controlling the flow rate of the solvent 5 supplied to the supply port 8 of the nozzle 6c through 10c is provided. The flow rate of the solvent 5 is measured by the flow meter 27, and the valve 26 is controlled based on the measurement result, so that the supply amount of the solvent 5 to the nozzle 6c of the absorbing device 2 is controlled to a target value.

Therefore, the solvent 5 separated and regenerated in the stirrer 21 is supplied as an absorbent to the nozzle 6c of the absorber 2 together with the solvent 5 following the path shown by the arrow A.

The acidic water (H 2 O, HCl) storage layer 21b of the stirrer 21 and the neutralization / recovery device 35 are connected to the pipelines 32a, 32a.
b, 32c.

A pump 33 for drawing acidic water (H2O, HCl) in the acidic water storage layer 21b of the stirrer 21 into the pipe 32a is provided on the pipe 32a. A flow meter 34 that measures the flow rate of the acidic water passing through the pipes 32a, 32b, and 32c is provided in the pipe 32c. The supply flow rate of the acidic water supplied to the neutralization / collection device 35 is controlled based on the flow rate measured by the flow meter 34.

In the neutralization / recovery device 35, the acidic water (H 2 O, HC 2) supplied from the acidic water storage layer 21b of the stirrer 21 is used.
l) is converted to the reaction of the above formula (2) (HCl
+ NaOH → NaCl + H2O), and is harmed and collected. Alternatively, acidic water in which hydrogen chloride is dissolved is concentrated and recovered in hydrochloric acid. From the stirrer 21 to the neutralization / recovery device 35, not only the acidic water but also the solvent 5 is slightly supplied. Then, the solvent 5 is recovered in the neutralization / recovery device 35 and used as a replenishing solvent for the tank 22.

The pipe 32b is connected to the pipe 36 via the pipe 32d.
b. For this reason, a part of the acidic water in the pipe 32b is mixed with the water passing through the pipe 36a, and is supplied to the agitator 21 of the reaction apparatus 3 as a harm-reducing agent after the acidity is reduced.

The gas reservoir (H 2, HCl gas) 21 a of the stirrer 21 and the wet scrubber 31 are communicated with each other by pipes 29 and 30.

In the wet scrubber 31, the same detoxification processing as described above with reference to FIG. 2 is performed.

That is, the H 2 and HCl gases are supplied to the wet scrubber 31 through the pipe 30. As a result, the caustic soda aqueous solution 40 is brought into gas-liquid contact with H2 and HCl gas, and the reaction of the above formula (2) (HCl + NaOH → NaCl + H) is performed.
By 2O), hydrogen chloride gas is removed by neutralization.

As described above, according to the present embodiment, the exhaust gas 4 is brought into gas-liquid contact with the solvent 5 in the chamber 6 of the absorption device 2 so that the harmless substance ( A solution 5 'is formed which has absorbed SiHCl3). The detoxification is performed by reacting the liquids (solution 5 'and H2O) at a place different from the chamber 6. Therefore, the harmless solid substance 4 generated by the reaction 4
2 (SiO2) can be reliably removed without being deposited in the chamber 6. In the above description, each unit 1
Although the configuration is based on the number of units, it is also possible to configure with a plurality of units. It can be implemented in various variations such as a continuous type and a batch type.

As described above, according to the present embodiment, it is possible to eliminate the deposition of a solid substance at a place where gas-liquid contact is made while maintaining a high gas-liquid contact efficiency. In addition, troubles such as equipment stop loss can be eliminated.

In this embodiment, the treatment of the exhaust gas from the epitaxial growth furnace is assumed, but the present invention is not limited to this, and the target equipment from which the exhaust gas is discharged is arbitrary.

In this embodiment, the stirrer 2 of the reactor 3 is used.
Although water H2O is supplied as a harm-removing agent in the method 1, an aqueous solution of caustic soda (NaOHaq) may be supplied as a harm-removing agent.

In this embodiment, the same device as the conventional jet scrubber is used as the absorption device 2. However, the exhaust gas 4 and the solvent 5 are brought into gas-liquid contact with each other to cause the solvent 5 to remove the harmful substances (SiHCl) in the exhaust gas 4. The configuration of the absorbing device 2 is arbitrary as long as it can absorb silicon chloride (such as silicon chloride).

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an exhaust gas treatment apparatus according to an embodiment.

FIG. 2 is a diagram showing a part of a conventional jet scrubber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas treatment apparatus 2 Absorption apparatus 3 Reactor 4 Exhaust gas 5 Solvent 5 'solution 6 Chamber 6c Jet nozzle

Claims (5)

[Claims] Claims: 1. An exhaust gas detoxifying method for removing a harmful substance by reacting a harmful harmful substance in an exhaust gas with a specific liquid to generate a harmless solid substance, By preparing a solvent that dissolves the harmless substance by gas-liquid contact with the exhaust gas and does not generate the harmless solid substance, and brings the solvent and the exhaust gas into gas-liquid contact, the harmful substance is removed. A step of producing a solution of the exhaust gas, comprising: a step of producing the harmless solid substance by reacting the generated solution of the harmful substance and the specific liquid. Abatement method. 2. The harmless substance to be harmed is silicon chloride, the specific liquid is water or an aqueous solution of caustic soda, and the harmless solid substance is silicon oxide. Exhaust gas removal method as described in the above. 3. The method of claim 1, wherein the solvent is an oil or a fluorine-based inert liquid. 4. An exhaust gas abatement apparatus for removing a harmful substance by reacting a harmful harmful substance in an exhaust gas with a specific liquid to generate a harmless solid substance, By preparing a solvent that dissolves the harmless substance by gas-liquid contact with the exhaust gas and does not generate the harmless solid substance, and brings the solvent and the exhaust gas into gas-liquid contact, the harmful substance is removed. A solution generating means for generating a solution of the harmful substance and a solid substance generating means for generating the harmless solid substance by reacting the generated solution of the harmful substance with the specific liquid. Characteristic exhaust gas abatement device. 5. The solution generating means is for bringing the solvent and the exhaust gas into gas-liquid contact in a chamber and ejecting a solution of the harmful substance from an outlet of a nozzle in the chamber. The exhaust gas abatement apparatus according to claim 4, wherein