JP6770823B2 - Degassing method and equipment for chemicals - Google Patents

Description

The present invention relates to a method and an apparatus for degassing a chemical solution in which a drug is dissolved in water.

Chemical solutions obtained by dissolving chemicals in water are used in various fields, but many of the chemicals contained in these chemicals are corrosive and volatile. For example, in the manufacturing process of semiconductor devices, hydrofluoric acid in which hydrogen fluoride is dissolved in water is used for cleaning wafers, etc., but hydrogen fluoride is highly corrosive and has a boiling point of around 20 ° C. Has strong volatility. In addition, a chemical solution in which a water-soluble organic substance is dissolved in water may be used, but the water-soluble organic substance contained in the chemical solution is generally volatile and may have a property of attacking rubber, plastic, or the like.

When the above-mentioned chemical solution is used in a semiconductor device manufacturing process or the like, if the chemical solution contains air bubbles or the like, good treatment cannot be performed. Therefore, it is necessary to perform degassing treatment on the chemical solution in advance. Patent Document 1 discloses that a chemical solution is degassed using a degassing module having a hollow fiber membrane as a degassing film. Patent Document 2 relates to a piston type vacuum pump, a diaphragm type vacuum pump, a scroll type vacuum pump, and a vacuum pump for using a degassing film when degassing a chemical solution and depressurizing the gas side of the degassing film. It discloses that a pump such as a screw type vacuum pump is driven by a fluid. By using the degassing membrane, it is possible to obtain a clean degassing chemical solution while preventing the generation of fine particles and the like.

Japanese Unexamined Patent Publication No. 9-94447 Japanese Unexamined Patent Publication No. 2003-10604

When a chemical solution containing a volatile drug is degassed by membrane degassing, the drug contained in the chemical solution leaks from the gas side of the degassed membrane in addition to the degassed gas. If the leaked chemical is corrosive, it adversely affects the vacuum pump used to depressurize the gas side of the degassing membrane.

An object of the present invention is, for example, a method and an apparatus for membrane degassing a chemical solution containing a corrosive chemical, which can suppress the occurrence of corrosion due to a chemical leaking to the gas side of the degassing membrane. Is to provide.

The degassing method of the present invention is a degassing method in which a chemical solution in which a drug is dissolved in water is degassed, and the gas side of the degassing membrane is depressurized while passing the chemical solution through the liquid side of the degassing membrane. For decompression on the gas side, the decompression state generated by a vacuum ejector using water as the working fluid is used.

The degassing device of the present invention is a degassing device that degass a chemical solution in which a drug is dissolved in water, and is a degassing module having a degassing film and allowing the drug solution to pass through the liquid side of the degassing film. It has a vacuum ejector connected to a degassing module and using water as a working fluid, and the gas side of the degassing film is depressurized by the decompression state generated by the vacuum ejector.

In the present invention, a vacuum ejector using water as a working fluid is used to reduce the pressure on the gas side of the degassing membrane when the chemical solution is degassed. Even if a chemical solution containing a corrosive and volatile chemical is degassed, the chemical leaking to the gas side of the degassing membrane will immediately dissolve in water, which is the working fluid, so that corrosion will occur in the degassing device. Etc. can be suppressed. Moreover, since the vacuum ejector does not have a moving part, it is easier to provide a corrosion-resistant coating on the surface of the vacuum ejector than a vacuum pump having a moving part, and even if corrosion or the like occurs, the operation of the device can be performed. The impact is small. Therefore, according to the present invention, it is possible to suppress the occurrence of corrosion due to the chemical leaking to the gas side of the degassing membrane by a simple means, and to realize a degassing device that operates stably at an inexpensive maintenance cost.

It is a figure explaining the degassing device of one Embodiment of this invention.

Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an deaeration device according to an embodiment of the present invention.

The degassing device 10 shown in FIG. 1 is a degassing device that degass a chemical solution in which a drug is dissolved in water. Broadly speaking, the degassing module 11 that performs membrane degassing of the chemical solution and the degassing module 11 It is provided with a vacuum ejector 12 that generates the required decompression. A degassing membrane 20 is provided on the degassing module 11, and an outlet valve 15 and an inlet valve 16 are connected to the liquid side of the degassing membrane 20. As the degassing module 11, for example, a module using a hollow fiber membrane can be preferably used. The chemical solution to be degassed is supplied from the outside, flows into the degassing module 11 via the inlet valve 16, passes through the liquid side of the degassing membrane 20, and flows out from the degassing module 11, and the outlet valve 15 is closed. It is sent to the supply destination of the chemical solution via. A valve 17 communicating with the gas side of the degassing membrane 20 and a pressure gauge 14 are connected to the degassing module 11. The other end of the valve 17 is connected to the decompression port of the vacuum ejector 12. The vacuum ejector 12 uses water as a working fluid and generates decompression. Water, which is a working fluid, is supplied through the inlet valve 18 and pumped to the vacuum ejector 12 by the pump 13. The water that has passed through the vacuum ejector 12 is discharged to the outside as drainage through the discharge valve 19. It is not always necessary to provide the pump 13 when water having a sufficient pressure for operating the vacuum ejector 12 can be obtained.

In the degassing device 10 based on the present invention, the inlet valve 18 and the discharge valve 19 are opened, and the pump 13 is operated to pass water, which is a working fluid, to the vacuum ejector 12. As a result, the decompression port of the vacuum ejector 12 is in a decompression state, and by opening the valve 17, the gas side of the degassing membrane 20 in the degassing module 11 is also in a decompression state. If the inlet valve 16 and the outlet valve 15 are opened to introduce the chemical solution into the degassing module 11 and allow the liquid side of the degassing membrane 20 to pass through, the membrane degassing of the chemical solution is performed. At this time, the valve 17 is operated based on the indicated value of the pressure gauge 14, and the pressure on the gas side of the degassing membrane 20 is adjusted according to the type of the chemical solution and the like. When the drug is volatile, the gas degassed by the membrane degassing of the drug solution (for example, water vapor, dissolved nitrogen, dissolved oxygen, etc.) contains the drug in the gas phase state, but the degassed gas. The chemical contained in is immediately dissolved in water, which is the working fluid, in the vacuum ejector 12, and is discharged from the degassing device 10 as drainage. The wastewater containing this chemical discharged from the degassing device 10 is treated with wastewater as necessary.

In the degassing device 10 of the present embodiment, a vacuum ejector 12 is used instead of the vacuum pump to generate a decompression state, and the degassing module 11 is operated. Even when a chemical solution containing a corrosive chemical is degassed, since a vacuum pump having a moving part is not used, countermeasures against corrosion can be reduced. Further, since the chemical leaked to the gas side of the degassing membrane 20 is immediately dissolved in water which is a working fluid, measures against corrosion can be reduced in that respect as well. Therefore, the degassing device of the present embodiment is particularly effective in degassing a chemical solution obtained by dissolving a corrosive and volatile chemical in water.

The chemical solution effective for degassing in the degassing device of the present embodiment contains corrosive and volatile inorganic substances such as hydrogen fluoride, hydrogen chloride, nitric acid, ammonia, and ammonium fluoride as chemicals. It is a waste. In addition, water-soluble substances such as dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), acetone, methyl ethyl ketone, various alcohols, phenols, amines and thinners. The degassing device of the present embodiment can also be effectively used for degassing a chemical solution containing an organic substance as a drug.

In the degassing device of the present embodiment, the water that is the working fluid of the vacuum ejector 12 may be pure water or tap water. Furthermore, it is also possible to use water containing the same drug as the drug solution to be degassed at a lower concentration than the drug solution to be degassed. If it is necessary to treat the chemicals leaked to the gas side of the degassing membrane due to degassing, if wastewater that must contain the chemicals in a low concentration and be treated as wastewater can be obtained separately. By using the wastewater as the working fluid of the vacuum ejector 12, the wastewater treatment cost can be reduced as a whole. As an example of such a case, there is a first step of processing the work using the degassed chemical solution, and a second step is carried out on the work as a post-treatment of the first step. In this case, the wastewater from the second step contains a low concentration of the drug. The chemical solution used in the first step is degassed by, for example, a circulation treatment.

FIG. 1 also shows an application form of the degassing device 10 of the present embodiment when the first step and the second step are provided. Here, for example, a case where the work 70 which is semiconductor wear is washed with a chemical solution which is hydrofluoric acid, for example, and then the work 70 is rinsed with pure water as a subsequent step is considered.

A cleaning device 30 for cleaning the work 70 with hydrofluoric acid is provided. The cleaning device 30 includes a cleaning tank 31 that stores chemicals and performs immersion cleaning, a filter 33 that removes fine particles and the like in the chemicals, and a circulation pump 32 that circulates the chemicals between the cleaning tank 31 and the filter 33. It is provided and constitutes a circulation system for chemicals. The circulation pump 31 is provided on the inlet side of the filter 33. In this circulation system, a circulation valve 34 is provided between the outlet of the filter 33 and the cleaning tank 31. An outlet valve 36 for sending the chemical solution to the degassing device 10 is branched at the inlet of the circulation valve 34, and an inlet valve for receiving the degassed chemical solution from the degassing device 10 is provided at the outlet of the circulation valve 34. 35 are provided so as to merge.

The rinsing device 50 that rinses the work 70 with pure water has a rinsing tank 51 in which pure water is supplied via the water supply valve 52. The overflow of the rinsing tank 51 becomes drainage in the rinsing process, and this drainage is discharged to the outside through the discharge valve 53. An outlet valve 54 for sending the drainage from the rinsing tank 51 to the degassing device 10 is branched on the inlet side of the discharge valve 53. The rinsing device 50 is provided for rinsing the work 70 cleaned with hydrofluoric acid in the cleaning device 30 with pure water, and the work 70 transferred from the cleaning device 30 is rinsed. It is immersed in pure water in the tank 51. As a result, the wastewater overflowing from the rinse tank 51 contains hydrofluoric acid at a low concentration, and when this wastewater is discharged to the outside, wastewater treatment for removing fluoride is required.

Therefore, in the present embodiment, when the chemical solution in the cleaning device 30 is degassed, the inlet valve 35 and the outlet valve 36 of the cleaning device 30 are connected to the outlet valve 15 and the inlet valve 16 of the degassing device 10, respectively. The outlet valve 54 of the rinsing device 50 is connected to the inlet valve 18 of the degassing device 10. Then, the circulation valve 34 is closed in the cleaning device 30, the inlet valve 35 and the outlet valve 36 are opened, and the outlet valve 15, the inlet valves 16, 18 and the discharge valve 19 are opened in the degassing device 10. In the rinsing device 50, the discharge valve 53 is closed, the outlet valve 18 is opened, and the water supply valve 52 is further opened to supply pure water to the rinsing tank 51. If the circulation pump 32 of the cleaning device 30 is operated in this state, the chemical solution in the cleaning device 30 circulates in the degassing module 11 of the degassing device 10 and passes through the liquid side of the degassing film 20 of the degassing module 11. Liquid. Then, when the pump 13 of the degassing device 10 is operated, the vacuum ejector 12 is operated by the drainage from the rinsing device 50, and the gas side of the degassing membrane 20 in the degassing module 11 is in a depressurized state. At this time, the valve 17 is operated to adjust the degree of vacuum on the gas side of the degassing membrane 20. As a result, the degassing device 10 performs the degassing treatment of the chemical solution of the cleaning device 30.

The wastewater from the vacuum ejector 12 contains hydrogen fluoride, which is a chemical component, and wastewater treatment to remove fluoride is required to discharge it to the outside. However, the wastewater discharged from the vacuum ejector 12 is Since the wastewater discharged from the rinsing device 50 required wastewater treatment in the first place, the wastewater treatment cost of the entire system did not increase, but rather the fluoride leaked to the gas side by the degassing treatment. The cost is reduced as compared with the case where hydrogen fluoride and hydrogen fluoride contained in the waste water from the rinsing device 50 are treated separately. Further, since the pump 13 in the degassing device 10 supplies the drainage from the rinsing device 50 which is a liquid, even if the drainage from the rinsing device 50 contains hydrogen fluoride, the degassing module 11 Compared to a vacuum pump when a vacuum pump is used for depressurization, it is less susceptible to corrosion by hydrogen fluoride.

As is clear from the above description, in the configuration shown in FIG. 1, existing cleaning devices 30 and rinsing devices 50 can be used, and an inlet valve 35 and an outlet valve 36 are added to the cleaning device 30. By simply adding the outlet valve 54 to the rinsing device 50, the degassing device 10 of the present embodiment can be used to degas the chemical solution while reducing the wastewater treatment cost. As an example, the circulation flow rate and circulation pressure of the chemical solution passed through the degassing module 11 of the degassing device 10 are set to 25 L / min and 0.3 MPa, respectively, and the flow rate and pressure of water as a working fluid to the vacuum ejector 12 are set. When the values are 50 L / min and 0.3 to 0.5 MPa, respectively, the displacement of 50 L / min and the exhaust pressure of 5 to 10 kPa on the gas side of the degassing film 20 in the degassing module 11 can be achieved.

10 Degassing device 11 Degassing module 12 Vacuum ejector 13 Pump 20 Degassing film 30 Cleaning device 31 Cleaning tank 50 Rinse device 51 Rinse tank 70 Work

Claims (6)

It is a degassing method that degass a chemical solution in which a drug is dissolved in water.
The gas side of the degassing membrane is depressurized while passing the chemical solution through the liquid side of the degassing membrane.
For the decompression on the gas side, the decompression state generated by the vacuum ejector using water as the working fluid is used .
A degassing method in which water used as the working fluid contains the drug at a lower concentration than the drug solution . The chemical solution is used in the first step of processing the work, and is used.
The water used as the working fluid comprises waste water discharged when performing the first process to the workpiece in the second step is a step after step, removal of Claim 1 Qi method. The degassing method according to claim 1 or 2 , wherein the drug comprises one or more compounds selected from the group consisting of hydrogen fluoride, hydrogen chloride and ammonia. A degassing device that degass a chemical solution in which a drug is dissolved in water.
A degassing module having a degassing membrane and allowing the chemical solution to pass through the liquid side of the degassing membrane.
A vacuum ejector connected to the degassing module and using water as a working fluid,
Have,
The gas side of the degassing membrane is decompressed by the decompression state generated by the vacuum ejector .
The water used as the working fluid contains the drug at a lower concentration than the chemical, degasser. The chemical solution is used in the first processing apparatus for processing the work.
The removal according to claim 4 , wherein the water used as the working fluid includes wastewater discharged from a second treatment device arranged after the first treatment device and treating the work. Qi device. The degassing device according to claim 4 or 5 , wherein the agent comprises one or more compounds selected from the group consisting of hydrogen fluoride, hydrogen chloride and ammonia.

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