WO2023189306A1

WO2023189306A1 - Cleaning method, cleaning liquid, and cleaning agent for exhaust gas treatment facility

Info

Publication number: WO2023189306A1
Application number: PCT/JP2023/008698
Authority: WO
Inventors: 慎吾原島
Original assignee: 栗田工業株式会社
Priority date: 2022-03-30
Filing date: 2023-03-08
Publication date: 2023-10-05
Also published as: JP2023147648A; TW202340443A

Abstract

This exhaust gas treatment facility comprises: a combustion chamber 1 for combusting wastewater; a nozzle for causing water to flow along the inner wall surface of the combustion chamber 1; a water supply line for supplying water to the nozzle; a primary smoke washing chamber 11; and a scrubber 20. When solids of the scrubber 20 are removed, an aqueous alkaline detergent solution is injected from a chemical injection device 50 into a lower water tank 44 to set the pH value to 8-14. The inside of the scrubber 20 is cleaned by operating a circulation pump 23 and sprinkling water from the nozzle 21. The cleaning solution having a pH of 8 to 14 may be sprinkled from above a mist catcher 40.

Description

Cleaning method, cleaning liquid and cleaning agent for exhaust gas treatment equipment

The present invention relates to a cleaning method, a cleaning liquid, and a cleaning agent for exhaust gas treatment equipment, and specifically relates to a cleaning method, cleaning liquid, and cleaning agent for exhaust gas treatment equipment for treating exhaust gas from semiconductor manufacturing processes, etc.

2. Description of the Related Art Manufacturing processes for semiconductors, liquid crystals, LEDs, solar cells, etc. emit exhaust gas containing perfluorinated compounds and the like. Note that this exhaust gas contains WF ₆ , CH ₂ F ₂ , Cl ₂ , BCl ₃ , F ₂ , HF, SiH ₄ , NH ₃ , PH ₃ , TEOS (tetraethoxysilane), TRIS (triethoxysilane), TiCl ₄ may also be included. Exhaust gas treatment equipment (abatement equipment) that processes such exhaust gas uses combustion, electric heating, plasma, etc. to perform a combustion (oxidation) or thermal decomposition reaction on perfluorinated compounds, and then The exhaust gas is washed in the smoke washing room, and _F2 , etc. in the gas is absorbed and removed.

The combustion treatment device for this exhaust gas is a water-cooled combustion system that allows water to flow down along the inner wall of the combustion chamber to prevent combustion products from adhering to the inner wall and protect the inner wall from combustion heat. There is a harm removal device (Patent Document 1).

Wet scrubbers are widely used as exhaust gas purification treatment devices (Patent Document 2).

Japanese Patent Application Publication No. 2003-24741 Publication No. 63-66132

In a water-cooled combustion type abatement device, deposits are likely to form inside the abatement device, in the piping, etc., and it is necessary to stop the abatement device and remove the deposits. Note that the deposits include oxides of tungsten (W), but other solids are also generated.

In conventional abatement equipment, when deposits are generated, the equipment is stopped and the operator performs cleaning work, which takes effort, cost, and time.

Patent Document 2 describes that a jet spray nozzle is installed at the bottom of a wet scrubber, and cleaning water is sprayed upward onto a porous plate in the scrubber to physically peel off and remove deposits. However, it is not possible to thoroughly clean the inside of a wet scrubber.

The present invention provides a method for cleaning exhaust gas treatment equipment, a cleaning liquid, and a cleaning agent that can sufficiently remove solid substances mainly composed of tungsten oxides such as deposits and attachments in exhaust gas treatment equipment in a short time. The challenge is to provide the following.

The cleaning method for exhaust gas treatment equipment of the present invention is a cleaning method for exhaust gas treatment equipment that processes exhaust gas from an electronic component manufacturing process, and the object to be cleaned in the wet exhaust gas treatment equipment is cleaned with an alkaline cleaning liquid having a pH of 8 to 14.

In one aspect of the present invention, the exhaust gas treatment equipment includes an abatement device that decomposes exhaust gas using heat, and a wet scrubber into which gas from the abatement device is introduced. The cleaning method is a method of cleaning the scrubber or its constituent members.

In one aspect of the present invention, the wet scrubber includes a lower water tank and a water sprinkling means to which water is circulated and supplied from the lower water tank by a circulation pump, and the method for cleaning the exhaust gas treatment equipment includes: and a step of supplying the water in the lower water tank to which the aqueous detergent solution has been added to the water sprinkling means.

In one aspect of the present invention, the wet scrubber includes a mist catcher, a water sprinkler is disposed above the mist catcher, and an alkaline cleaning solution with a pH of 8 to 14 is supplied to the water sprinkler to remove the mist catcher and the water sprinkler. Clean the inside of the lower wet scrubber.

In one aspect of the present invention, some components are removed from the wet scrubber and cleaned by immersing them in an alkaline cleaning solution with a pH of 8 to 14.

The cleaning liquid of the present invention is a cleaning liquid for exhaust gas treatment equipment that processes exhaust gas from electronic component manufacturing processes, and is composed of an alkaline solution with a pH of 8 to 14.

The cleaning agent of the present invention is a cleaning agent for preparing a cleaning liquid for exhaust gas treatment equipment that treats exhaust gas from an electronic component manufacturing process, and comprises an alkaline agent for making the cleaning liquid an alkaline solution with a pH of 8 to 14. .

In one aspect of the present invention, the alkali is choline or ammonia.

According to the present invention, solid matter in exhaust gas treatment equipment can be sufficiently dissolved and/or dispersed and removed in a short time using a cleaning agent. When the present invention is applied to manufacturing equipment for semiconductors, etc., the operating efficiency of the manufacturing process machine for semiconductors, etc. can be improved, and the productivity of semiconductors, etc. is improved.

FIG. 2 is a configuration diagram of the abatement equipment. It is a block diagram of a scrubber. It is a graph showing test results. It is a graph showing test results. It is a graph showing test results.

Hereinafter, an example of the abatement equipment to which the method according to the embodiment is applied will be described with reference to FIGS. 1 and 2.

In this abatement equipment, exhaust gas from a semiconductor manufacturing process and air from a blower are supplied to a burner 2 provided at the top of a tower-shaped combustion chamber 1, and the exhaust gas is combusted within the combustion chamber 1.

Note that the exhaust gas is preferably a gas generated in an electronic component manufacturing process, and a gas containing WF ₆ is particularly preferred. Silanes (SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl _{2 ,} etc.), gas components other than silane (B ₂ H ₆ , PH ₃ , NH ₃ , N ₂ O, H ₂ , H ₂ Se, GeHe, _AsH3 , _CH4 , _C2H4 , _CO , Cl2, F2, ClF3 _, _NF3 _, _CH2F2 _, NO _, _O2 , _CF4 _{, C4F8} _, _C5F8 _, _CHF3 ) may also be included.

A nozzle (not shown) is provided to flow water along the inner wall surface of the combustion chamber 1, and water is supplied to the nozzle by a water supply line. The water flowing out from this nozzle flows down the inner wall surface of the combustion chamber 1 in the form of a water film, and the inner wall surface is protected from combustion heat. Note that water flowing in the form of a water film on the inner wall surface of the combustion chamber 1 absorbs water-soluble components in the combustion gas and captures particulates. It also lowers the gas temperature.

Water flowing down the inner wall surface collects in the pit 1a at the bottom of the combustion chamber.

The water supply line to the nozzle includes a pipe 3, a pump 4, a pipe 5, and

pipes

6 and 7 branched from the pipe 5. A pipe 6 is connected to the nozzle, and a pipe 7 is provided to supply water to the pit 1a at the bottom of the combustion chamber 1.

A primary smoke cleaning chamber 11 is installed adjacent to the combustion chamber 1. The lower part of the combustion chamber 1 and the lower part of the primary smoke cleaning chamber 11 communicate with each other through a duct 12, and gas from the combustion chamber 1 is introduced into the primary smoke cleaning chamber 11 through the duct 12, and the gas from the combustion chamber 1 is introduced into the primary smoke cleaning chamber 11 through the duct 12. It ascends inside the smoke washing chamber 11.

Note that a part of the water in the pit 1a of the combustion chamber 1 flows out through the duct 12 into the pit 11a of the primary smoke cleaning chamber 11 by overflow. Part of the water in the pit 1a of the combustion chamber 1 may be transferred to the pit 11a by a water transfer pipe separate from the duct 12.

Water in the pit 11a at the bottom of the primary smoke washing chamber 11 is sprinkled by a sprinkler 16 via a pump 14 and piping 15. The gas rising in the primary smoke washing chamber 11 comes into contact with water sprinkled from the water sprinkler 16, and water-soluble components and fine particles in the gas are absorbed or captured by the water.

The gas that has passed through the primary smoke washing chamber 11 is introduced from the gas outlet 17 into the wet scrubber 20 through the gas inlet 25 by the duct 18 and the blower 19.

Water at the bottom of the wet scrubber 20 is supplied to the nozzle 21 (water sprinkling means) at the top of the wet scrubber 20 by a circulation pump 23 and piping 22. The gas comes into contact with the water sprayed from the nozzle 21, and after the water-soluble components and fine particles are absorbed or captured by the water, the gas flows out from the outlet 26. The wet scrubber 20 is supplied with water for gas cleaning through a pipe 24.

The water at the bottom of the combustion chamber 1, primary smoke chamber 11, and scrubber 20 is taken out via

pipes

31, 32, and 33, and is sent to a wastewater treatment facility (not shown) for treatment.

The details of the structure of the wet scrubber 20 are shown in FIG. 2. A mist catcher 40 is provided at the upper part of the wet scrubber 20. A grating 41 is provided below the nozzle 21.

A part of the lower water tank 44 of the wet scrubber 20 protrudes laterally, and the pump 23 is installed above it. The water in the lower water tank 44 is sucked into the pump 23 by the piping 22a, and is sent to the nozzle 21 via the piping 22.

The water sprayed from the nozzle 21 falls onto the intermediate plate 42 , passes through the water drop hole 43 provided in the intermediate plate 42 , and falls into the lower water tank 44 .

The gas inlet 25 is provided on the side wall surface of the wet scrubber above the intermediate plate 42.

The piping 24 is connected to the lower water tank 44. An overflow port 45 is provided at an upper portion of the side surface of the lower water tank 44. When the water level in the lower water tank 44 becomes higher than the overflow port 45, the water in the lower water tank 44 flows out from the overflow port 45 to the relay tank 46, and from the relay tank 46 to the pipe 33 via the pipe 47. leak.

A pipe 48 is provided to communicate the bottom of the lower water tank 44 with the pipe 47, and a valve 49 is provided in the pipe 48. The valve 49 is opened only when draining water from the lower water tank 44, and is closed at other times.

An aqueous solution of cleaning agent can be injected into the lower water tank 44 from a chemical injection device 50 via a pipe 51. The chemical injection device 50 includes a tank that stores an aqueous solution of a cleaning agent, a chemical injection pump, and a control circuit that controls the chemical injection pump.

In this embodiment,

pH meters

52 and 53 are provided in the piping 22 and the relay tank 46, respectively, and detection signals from the

pH meters

52 and 53 are transmitted to the control circuit.

To perform solid matter removal cleaning of the wet scrubber 20, after stopping the blower, a cleaning start command signal is input to the control circuit. When this signal is given, the control circuit starts the chemical injection pump and performs chemical injection such that the pH detected by the pH meter 52 is 8 to 14, particularly 10 to 13, particularly 11 to 13.

By injecting a cleaning agent aqueous solution into the wet scrubber 20 by the chemical injection device 50, a cleaning liquid consisting of an alkaline solution with a pH of 8 to 14 is ejected from the nozzle 21, and solid matter such as deposits and attachments is dissolved and/or dispersed. do.

In the above embodiment, the wet scrubber 20 is cleaned while the exhaust gas treatment is stopped, but the cleaning may be performed while the exhaust gas treatment is continued. Further, cleaning may be carried out periodically, or when the exhaust capacity and exhaust gas treatment performance are degraded due to adhesion of solid matter.

As described above, according to this cleaning method, the solid matter in the scrubber 20 can be sufficiently dissolved and removed in a short time with an alkaline cleaning solution having a pH of 8 to 14, particularly a pH of 10 to 13, and especially a pH of 11 to 13, thereby shortening the working time and It is possible to reduce labor costs.

In addition, in an embodiment in which cleaning is performed while exhaust gas treatment is continued, the shutdown of the semiconductor manufacturing process due to the shutdown of the exhaust gas treatment equipment is also prevented, and productivity is improved.

As the cleaning agent, alkaline agents such as inorganic alkaline agents such as sodium hydroxide, potassium hydroxide, ammonia, and sodium metasilicate, and organic alkaline agents such as choline and TMAH are suitable, but are not limited thereto. In addition to alkaline chemicals, cleaning agents include silica scale cleaning agents, solubilizing agents such as foaming agents (peroxide water, etc.) and chelating agents (EDTA, polyphosphoric acid, etc.), calcium scale inhibitors, slime control agents ( Dichloroglyoxime, 2,2-dibromo-2-nitroethanol, 2,2-dibromo-3-nitrilopropionamide, chlorosulfamic acid, bis-1,4-bromoacetoxy-2-butene, ametrine, 5-chloro- 2-methyl-4-isothiazolin-3-one) and the like. The alkaline agent may be a waste alkali from an electronic parts factory or the like.

The above embodiment is an example of the present invention, and the present invention may have other forms than the above. For example, in the embodiment described above, the cleaning agent aqueous solution is caused to flow out from the nozzle 21 by the circulation pump 23, but a submersible pump is arranged in the lower water tank 44, a water sprinkler is arranged above the mist catcher 40, and the submersible pump Discharged water may be supplied to the sprinkler through a hose to sprinkle water to dissolve and/or disperse and remove solids in the mist catcher 40 and the area below it.

This submersible pump can be placed in the lower water tank 44 through a lower water tank inspection port provided near the circulation pump 23. Further, the hose can be drawn out of the wet scrubber 20 through the lower water tank inspection port and into the upper part of the scrubber 20 through the inspection window (not shown) on the side of the wet scrubber 20 or the outlet 26.

In the embodiment described above, an alkaline cleaning agent aqueous solution is added to the lower water tank 44, and the water in the lower water tank 44 is used as a cleaning liquid with a pH of 8 to 14. Then, this cleaning liquid may be supplied to the nozzle 21 or a water sprinkler above the mist catcher 40.

In the above embodiment, the inside of the wet scrubber is cleaned with a cleaning liquid, but the components of the wet scrubber (for example, the nozzle, mist catcher, lower water tank, etc.) are removed from the scrubber, and the cleaning tank containing the cleaning liquid with a pH of 8 to 14 is cleaned. It may also be cleaned by immersing it in a cleaning solution.

In the above embodiment, solid matter is removed from the wet scrubber 20, but other objects to be cleaned such as the primary smoke cleaning chamber 11 and the blower 19 may be cleaned with an alkaline cleaning liquid having a pH of 8 to 14. In this case as well, the cleaning liquid may be circulated and supplied to the object to be cleaned, or the component may be removed and immersed in the cleaning liquid for cleaning.

In the above embodiment, the abatement device is a "combustion type," but it is not limited to this, and any device that uses heat, such as an electric heating type or a plasma type, may be used.

[Test example 1]
Solid substance dissolution tests were conducted using various alkaline aqueous solutions. As a reference example, solubility in ultrapure water (UPW) was also tested.

<Test method>
≪Sample solid matter≫
The sample was sediment collected from a scrubber installed after the abatement equipment in the semiconductor manufacturing process. When the components were analyzed, the W content was about 55 wt% on a dry basis, and the Si content was about 10 wt% on a dry basis.

≪Type and concentration of alkali≫
Aqueous solutions of NaOH, choline, and ammonia were used as alkalis. The concentrations were 0.01, 0.1, and 1 wt% as weight % (wt%).

≪Test procedure≫
The test procedure was as follows.
i) Take 0.3 g (initial amount y) of the solid and add it to 300 ml of aqueous alkaline solution.
ii) Stir with a stirrer for 10 minutes.
iii) The solution in ii) above is suction filtered through a 1 μm glass filter, and the dry weight of the residue on the filter is measured.
iv) Calculate the ratio of the amount (x) of the initial amount of solids that passed through the glass filter as the dissolution rate.
That is,
Dissolution rate = (1-x/y) x 100%
It is.
v) Measure the SEM EDX of the residue.

<Test result 1>
The solubility of solids in each alkaline aqueous solution was investigated. The results are shown in Table 1 and FIG. 3.

As shown in Table 1 and FIG. 3, it was found that choline and ammonia exhibit high solubility under conditions of stirring time of 10 minutes.
It was also suggested that the higher the alkali concentration, the higher the dissolution rate.
On the other hand, with NaOH, even if the concentration increased, the dissolution rate did not increase in some cases.

<Test results 2>
The concentration of choline and stirring time necessary for dissolving solids using choline were investigated. The results are shown in Table 2 and FIG. 4.

As shown in Table 2 and Figure 4, in the case of 0.1 wt% choline, if solid components to be dissolved remain, the reaction gradually progresses and the dissolution rate increases as the stirring time increases. Ta.
In the case of 1 wt% choline, it was found that if the alkali concentration was sufficiently high relative to the solid matter concentration, it could be dissolved even if the reaction time was short.

<Consideration>
Looking at the results in Figures 3 and 4, 1 wt% choline and ammonia showed a high dissolution rate.
From these results, it was confirmed that high concentrations of choline and ammonia have a high ability to dissolve the solid substance.

[Test example 2]
A dissolution test was conducted with different amounts of solids (sediment collected from a scrubber) added to the choline aqueous solution.

<Test method>
To 100 mL of 1 wt% choline aqueous solution, add solid matter (sediments collected from a scrubber installed after the abatement equipment in the semiconductor manufacturing process) to a concentration of 0.5, 1, 2, 3, or 5 wt%. Sample No. I gave it a rating of 1 to 5. Each solution was stirred with a stirrer, and changes in pH and appearance (photographs were taken from the bottom of the beaker) over time were measured and observed. Table 3 shows the test conditions for each sample. Since the volume of all solutions is 100 mL, the amount of solid added directly becomes the wt% concentration.

<Results>
Table 4 shows the results of stirring and measuring the pH of each sample over time. Further, a graph of this result is shown in FIG.

Looking at Figure 5, the pH of the solutions with a solid concentration of 2 to 5 wt% (sample Nos. 3, 4, and 5) decreased to 7.2 to 7.6 after 30 to 45 minutes of stirring, and then stabilized. . This means that the amount of solid matter is large compared to the amount of choline. Looking at the results of appearance observation, sample No. In samples 3 to 5, clear undissolved solids were observed.

On the other hand, in the solutions with a solid concentration of 0.5 to 1 wt% (sample Nos. 1 and 2), the pH decreased with stirring and remained almost stable in the alkaline range even after 24 hours of stirring. Looking at the results of appearance observation, sample No. In sample No. 1, after 5 hours of stirring, sample No. In No. 2, it was observed that most of the solids were dissolved after 24 hours of stirring.

From this, it can be seen that the pH of the cleaning liquid needs to be 8 or higher, and in order to sufficiently dissolve the solids in a short time, the pH needs to be 10 or higher. It has also been suggested that the cleaning effect can be confirmed by changes in pH.

<Consideration>
The following three findings were obtained from the test results.
- pH decreases as solids dissolve.
・If solid matter remains, the pH will be stable in the neutral range.
- The higher the pH, the higher the effect of dissolving solids.

Based on these facts, when considering on-site cleaning of solid materials, additional alkali is injected when the pH reaches neutrality, and if the pH stabilizes for a while in the alkaline range, it is determined that the solids have dissolved. Control methods can be considered. Furthermore, the reaction rate becomes faster as the concentration of the alkali increases, so if cleaning is required in a short time, it is considered that cleaning should be performed with an alkali having a concentration equal to or higher than the concentration of solids.

Although the invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various changes can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2022-055285 filed on March 30, 2022, which is incorporated by reference in its entirety.

1 Combustion chamber 2 Burner 4 Pump 11 Primary smoke cleaning chamber 20 Scrubber 21 Nozzle 23 Circulation pump 40 Mist catcher 44 Lower water tank 46 Relay tank 50

Chemical dosing device

52, 53 pH meter

Claims

A method for cleaning exhaust gas treatment equipment for treating exhaust gas from an electronic component manufacturing process, the method comprising:
A method for cleaning exhaust gas treatment equipment, comprising cleaning an object to be cleaned in the exhaust gas treatment equipment with an alkaline cleaning solution having a pH of 8 to 14.
The exhaust gas treatment equipment includes an abatement device that decomposes exhaust gas using heat, and a wet scrubber into which gas from the abatement device is introduced,
2. The method of cleaning exhaust gas treatment equipment according to claim 1, wherein the method of cleaning exhaust gas treatment equipment is a method of cleaning the wet scrubber or its constituent members.
The wet scrubber has a lower water tank and a water sprinkling means to which water is circulated and supplied from the lower water tank by a circulation pump,
The method for cleaning exhaust gas treatment equipment includes the steps of: adding a cleaning agent aqueous solution to the lower water tank; and supplying water in the lower water tank to which the cleaning agent aqueous solution has been added to the watering means. Item 2. Method for cleaning exhaust gas treatment equipment.
The wet scrubber is equipped with a mist catcher,
Place a water sprinkler above the mist catcher,
3. The method for cleaning exhaust gas treatment equipment according to claim 2, wherein an alkaline cleaning liquid having a pH of 8 to 14 is supplied to the water sprinkler to clean the inside of the mist catcher and the wet scrubber below it.
The method for cleaning exhaust gas treatment equipment according to claim 2, wherein some components are removed from the wet scrubber and cleaned by immersing them in an alkaline cleaning solution with a pH of 8 to 14.
The method for cleaning exhaust gas treatment equipment according to any one of claims 1 to 5, wherein the alkali is choline or ammonia.
A cleaning liquid for exhaust gas treatment equipment that processes exhaust gas from electronic component manufacturing processes,
A cleaning solution for wet exhaust gas treatment equipment consisting of an alkaline solution with a pH of 8 to 14.
The cleaning liquid for exhaust gas treatment equipment according to claim 7, wherein the alkali is choline or ammonia.
A cleaning agent for preparing a cleaning liquid for exhaust gas treatment equipment that processes exhaust gas from an electronic component manufacturing process,
A cleaning agent for exhaust gas treatment equipment, comprising an alkaline agent for making the cleaning liquid an alkaline solution with a pH of 8 to 14.
The cleaning agent for exhaust gas treatment equipment according to claim 9, wherein the alkaline agent is choline or ammonia.