JPH10174854A - Gas dissolver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently clean off the org. matter, unreacted fluorine ion, etc., depositing on a gas-permeable membrane in a gas dissolver for dissolving a gas supplied through the gas-permeable membrane by providing a hot water feed pipe for cleaning the the membrane. SOLUTION: A hot water feed pipe 13 for supplying hot water from a hot water feeder 12 through a switching valve 11a is connected to an existing water feed pipe 7 for supplying ultrapure water to a gas dissolver 1 from an ultrapure water feeder 3. Further, a hot water feed pipe 13 for supplying hot water from the hot water feeder 12 through a switching valve 11b is connected to an existing gas feed pipe 8 for supplying a gas to the dissolver 1 from a gas feeder 4. The hot water for cleaning a gas-permeable membrane 2 is supplied to the dissolver 1. The hot water to be supplied to the dissolver 1 from the feeder 12 is preferably controlled to 45-65 deg.C, and the hot water should be supplied at 2-5l/min for >=5hr although it depends on the size of the gas-permeable membrane to be cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas dissolving apparatus, for example, a wet processing apparatus for cleaning electronic components such as a semiconductor substrate, a glass substrate, an electronic component, or a component of the manufacturing apparatus, or an optical lens. At
The present invention relates to a gas dissolving apparatus that can be used for adjusting a cleaning liquid in which a cleaning function gas such as hydrogen gas and ozone gas is dissolved in ultrapure water.

[0002]

2. Description of the Related Art In the process of manufacturing electronic parts such as LSIs, it is sometimes required to make the surface extremely clean. For example, in LSI, a silicon oxide insulating film is formed on a silicon wafer, a resist layer is provided in a predetermined pattern on the silicon film, and the insulating film in a portion where the resist layer is not provided is removed by etching or the like to remove metal silicon. After exposing the surface and cleaning the surface, a step (lithography process) of introducing a p-type or n-type element according to the purpose and embedding a metal wiring such as aluminum is repeated to manufacture an element. When introducing an n-type element or embedding metal wiring, if foreign matter such as fine particles, metal, organic matter, natural oxide film, etc. adhere to the metal silicon surface, the metal silicon and the metal wiring may The characteristics of the element may be poor due to poor contact or increased contact resistance. For this reason, in the LSI manufacturing process, the step of cleaning the surface of the silicon wafer is a very important step for obtaining a high-performance device, and it is necessary to remove impurities adhering to the silicon wafer as much as possible.

Conventionally, cleaning (wet processing) of a silicon wafer is performed by cleaning with a mixed solution of sulfuric acid and hydrogen peroxide, a mixed solution of hydrochloric acid and hydrogen peroxide, a hydrofluoric acid solution, an ammonium fluoride solution, and the like, and using ultrapure water. The cleaning is performed in combination to remove organic substances, fine particles, metals, natural oxide films and the like adhering to the silicon wafer surface without impairing the flatness of the silicon wafer surface at the atomic level.

The following (1) to (13) are specific examples of a conventional silicon wafer cleaning process. (1) Sulfuric acid / hydrogen peroxide solution washing step; a mixed solution of sulfuric acid: hydrogen peroxide solution = 4: 1 (volume ratio) at 130 ° C.
Wash for 0 minutes. (2) Ultrapure water washing step; washing with ultrapure water for 10 minutes. (3) Hydrofluoric acid washing step; washing with 0.5% hydrofluoric acid for 1 minute. (4) Ultrapure water washing step; washing with ultrapure water for 10 minutes. (5) Ammonia / hydrogen peroxide water washing step; washing with a mixed solution of ammonia water / hydrogen peroxide / ultra pure water = 0.05: 1: 5 (volume ratio) at 80 ° C. for 10 minutes. (6) Ultrapure water washing step; washing with ultrapure water for 10 minutes. (7) Hydrofluoric acid washing step: washing with 0.5% hydrofluoric acid for 1 minute. (8) Ultrapure water washing step: washing with ultrapure water for 10 minutes. (9) Hydrochloric acid / hydrogen peroxide water washing step: a mixed solution of hydrochloric acid: hydrogen peroxide water: ultra pure water = 1: 1: 6 (volume ratio)
Wash at 80 ° C for 10 minutes. (10) Ultrapure water washing step; washing with ultrapure water for 10 minutes. (11) Hydrofluoric acid washing step; washing with 0.5% hydrofluoric acid for 1 minute. (12) Ultrapure water washing step; washing with ultrapure water for 10 minutes. (13) Spin drying or IPA vapor drying

The step (1) is mainly for removing organic substances adhering to the surface of the silicon wafer,
The step (5) is mainly for removing fine particles adhering to the silicon wafer surface, and the step (9) is mainly for removing metal impurities on the silicon wafer surface. Steps (3), (7) and (11) are performed to remove the natural oxide film on the surface of the silicon wafer. In addition, the cleaning liquid in each of the above steps often has a contaminant removing ability other than the above-mentioned main purpose. For example, the mixed solution of sulfuric acid and hydrogen peroxide used in the step (1) is not only organic but also organic substances. Since it also has a strong action of removing metal impurities, in addition to the above-described method of removing different impurities by each cleaning solution, there is also a method of removing a plurality of impurities with one type of cleaning solution.

In the wet processing of a silicon wafer, a method of bringing a cleaning liquid or ultrapure water into contact with the surface of the silicon wafer generally includes a batch cleaning method in which a plurality of silicon wafers are immersed in a cleaning tank containing the cleaning liquid or ultrapure water. A method called washing is performed while circulating and filtering the cleaning liquid to prevent contamination of the cleaning liquid, and as a cleaning method using ultrapure water after treatment with the cleaning liquid, ultrapure water is supplied from the bottom of the cleaning tank. An overflow cleaning method that overflows from the top of the cleaning tank, and then stores the ultrapure water in the cleaning tank until the entire surface of the wafer is immersed in the ultrapure water, and then quickly discharges the ultrapure water from the bottom of the cleaning tank at once. Laws have also been adopted. In recent years, in addition to the batch cleaning method, a method of spraying a cleaning liquid or ultrapure water on a wafer surface in a shower shape or cleaning the wafer by rotating the wafer at a high speed and spraying a cleaning liquid or ultrapure water on the center thereof. A so-called single wafer cleaning method such as a method is also employed.

The cleaning with ultrapure water is performed to rinse (rinse) a cleaning liquid or the like remaining on the wafer surface. Therefore, the ultrapure water used for rinsing is high purity ultrapure water from which fine particles, colloidal substances, organic substances, metal ions, anions, dissolved oxygen and the like have been removed to an extremely low level. This ultrapure water is also used as a solvent for the cleaning liquid.

[0008]

In recent years, the degree of integration of LSI has been dramatically improved. In the early days, the number of lithography processes in the LSI manufacturing process was about several times.
From 30 times to 30 times, and the number of times of cleaning of the wafer also increases with the increase in the lithography process. For this reason, the raw material cost of the cleaning liquid and ultrapure water used for the wet processing of the wafer, the processing cost of the cleaning liquid and ultrapure water after use, and the cleaning liquid gas generated in the clean room due to the wet processing at a high temperature are discharged from the clean room. Costs, such as the cost of air, increase the product cost, reduce the concentration and use amount of the cleaning solution, lower the temperature of the wet process, reduce the number of processes per wet process, and rinse. There is a problem of reducing the amount of ultrapure water used for the process.

In view of the above problems, the present applicants have conducted intensive studies and have found that the oxidation-reduction potential of the cleaning solution and the rinsing solution is important. A method for cleaning electronic components with a cleaning liquid having a reduction potential, a method for cleaning with a cleaning liquid having a positive oxidation-reduction potential obtained by dissolving ozone gas in ultrapure water, and a method for negative oxidation obtained by dissolving hydrogen in ultrapure water A method of cleaning with a cleaning liquid having a reduction potential has been previously proposed.

When using ultrapure water in which a cleaning function gas such as hydrogen gas or ozone is dissolved as a cleaning liquid in a wet process, one of the methods for dissolving the cleaning function gas in the ultrapure water is a gas having a gas permeable membrane. There is a melting device.
This device has a hollow fiber membrane (gas permeable membrane) in a cylindrical vessel.
Are arranged in the axial direction of the vessel and a plurality of gas permeable membrane modules are provided. The hollow fiber membrane in this gas dissolving device has a plurality of micropores that penetrate inside and outside the hollow fiber body and allow gas to permeate but not liquid. When a gas such as hydrogen or ozone is dissolved in ultrapure water by the gas permeation device, an external pressure type and an internal pressure type are adopted. The external pressure method is a method in which a gas is supplied to the inside of the hollow fiber membrane, ultrapure water is supplied to the outside, and the gas permeated from the inside to the outside of the hollow fiber membrane is dissolved in the ultrapure water. In this method, ultrapure water is supplied to the inside of the fibrous membrane and gas is supplied to the outside to dissolve the gas permeated from the outside to the inside of the hollow fiber membrane in the ultrapure water.

If organic substances, dust, bacteria, and the like adhering to the gas permeable membrane during the production of the gas permeable membrane remain on the surface of the gas permeable membrane, there is a possibility that the organic substances, dust, and bacteria may be mixed in the cleaning liquid used for the wet treatment of the silicon wafer. There is. Further, since the gas permeable membrane is made of a hydrophobic material such as a fluorine-based resin, unreacted fluorine ions in the material constituting the gas permeable membrane may be mixed into the cleaning liquid. Such contamination of the cleaning liquid may significantly impair the wet processing of the silicon wafer.

For this reason, in a wet processing apparatus equipped with a gas permeable membrane type cleaning apparatus, the gas dissolving apparatus is cleaned before use, but conventionally, this cleaning is connected to the liquid supply side of the gas dissolving apparatus. It is performed by supplying ultrapure water from the ultrapure water supply pipe. However, by merely supplying ultrapure water to the liquid supply side of the gas dissolving apparatus and performing cleaning, the concentration of organic substances and fluorine ions mixed into the cleaning liquid is reduced.
It is difficult to reduce the concentration to a low concentration that does not hinder the cleaning of the silicon wafer in a short time, and there is a problem that a cleaning time of several days is usually required. In addition, in the conventional cleaning with ultrapure water, it is difficult to wash and remove the bacteria attached to the gas permeable membrane in a short time, and there is a possibility that the bacteria may propagate on the gas permeable membrane. Once bacteria have grown on the gas permeable membrane, it is necessary to remove the gas permeable membrane module from the gas dissolving device and perform sterilization cleaning, or replace the gas permeable membrane module. Since it cannot be used, there have been problems such as a decrease in wet treatment efficiency and an increase in maintenance costs.

The present invention has been made in view of the above points,
A gas dissolving device with a washing function that can efficiently wash and remove organic substances, dust, bacteria, etc. adhering to the gas permeable membrane and unreacted fluorine ions eluted from the constituent materials of the gas permeable membrane. It is intended to provide.

[0014]

According to the present invention, there is provided (1) a gas dissolving apparatus for dissolving a gas supplied through a gas permeable membrane into a liquid, the apparatus comprising hot water for cleaning the gas permeable membrane. A gas dissolving device having a supply pipe; (2) the gas dissolving device has a gas supply side and a liquid supply side partitioned by a gas permeable membrane, and the gas supply side has a gas supply side. A gas supply pipe for supplying gas from the supply device and a surplus gas discharge pipe for sending surplus gas to the gas treatment device are connected, and ultrapure water from the ultrapure water supply device is supplied to the liquid supply side. An ultrapure water supply pipe for supplying, and a cleaning liquid supply pipe for transferring a cleaning liquid obtained by dissolving a gas supplied from the gas supply device to the ultrapure water through a gas permeable membrane to a cleaning tank. Is connected to the gas dissolving apparatus according to (1), ) A hot water supply pipe for cleaning the gas permeable membrane is connected to a gas supply pipe for supplying gas to the gas dissolving device via a switching valve for switching between a gas supply side and a hot water supply side. The gas dissolving apparatus according to (2) above, and (4) a waste water pipe for guiding waste hot water discharged from the gas supply side of the gas dissolving apparatus after cleaning the gas permeable membrane to a waste water collecting apparatus, using a gas treatment. (3) The gas dissolving apparatus according to (3), wherein the gas dissolving apparatus is connected to a surplus gas discharge pipe for sending surplus gas to the apparatus via a switching valve that switches between a gas processing apparatus side and a waste water collecting apparatus side. (5)
A hot water supply pipe for cleaning the gas permeable membrane is provided with a switching valve that switches between the ultrapure water supply device side and the hot water supply device side in the middle of the ultrapure water supply pipe that supplies ultrapure water to the gas dissolving device. (6) The gas dissolving apparatus according to (2), wherein the exhausted hot water discharged from the liquid supply side of the gas dissolving apparatus after cleaning the gas permeable membrane is guided to the exhausted hot water recovery apparatus. The gas dissolving apparatus according to (5), wherein the hot water pipe is connected to the cleaning liquid supply pipe for transferring the cleaning liquid to the cleaning tank via a switching valve for switching between the cleaning tank side and the waste water collecting apparatus side. (7) A hot water supply pipe for cleaning the gas permeable membrane is connected to a gas supply pipe for supplying gas to the gas dissolving device via a switching valve for switching between a gas supply side and a hot water supply side. Ultrapure water that supplies ultrapure water to the gas dissolution equipment The gas dissolving device according to (2), wherein (8) gas permeation is provided by being connected via a switching valve for switching between the ultrapure water supply device side and the hot water supply device side in the middle of the supply pipe. The exhausted hot water pipe for guiding the exhausted hot water discharged from the gas supply side of the gas dissolving apparatus, which has washed the membrane, to the exhausted hot water recovery apparatus, in the middle of the excess gas exhaust pipe for sending the excess gas to the gas processing apparatus, It is connected via a switching valve that switches between the gas treatment device side and the waste water recovery device side, and has a waste water pipe for guiding the waste water discharged from the liquid supply side of the gas dissolving device to the waste water recovery device. The gas dissolving apparatus according to (7), wherein the gas dissolving apparatus is connected to a cleaning liquid supply pipe for transferring the cleaning liquid to the cleaning tank via a switching valve for switching between the cleaning tank side and the waste water collecting apparatus side. ) Gas dissolving device equipped with ultrasonic generator Characterized Rukoto (1) and gist gas dissolution device according to any one of - (8).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the gas dissolving apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration in a case where the gas dissolving apparatus of the present invention is provided in a wet processing apparatus. In the figure, 1 is a gas dissolving device, 2 is a gas permeable membrane, and the gas dissolving device 1 is a liquid supply side 1a partitioned by the gas permeable membrane 2.
And a gas supply side 1b. The wet processing apparatus includes a gas dissolving apparatus 1, an ultrapure water supply apparatus 3 including an ultrapure water producing apparatus for supplying ultrapure water to a liquid supply side 1a of the gas dissolving apparatus 1, and a gas dissolving apparatus 1. A gas supply device 4 for supplying a cleaning function gas such as hydrogen gas or ozone gas to the supply side 1b, and a cleaning liquid obtained by dissolving the cleaning function gas in ultrapure water via the gas permeable membrane 2, for example, a silicon wafer or the like And a gas treatment device 6 for treating excess gas supplied from the gas supply device 4 to the gas dissolving device 1. Ultrapure water is supplied from the ultrapure water supply device 3 to the liquid supply side 1 a of the gas dissolving device 1 by the ultrapure water supply pipe 7, and the cleaning function gas is supplied to the gas supply device 4.
From the gas supply pipe 8 to the gas supply side 1b of the gas melting device 1. The liquid supply side 1a of the gas dissolving device 1
The cleaning liquid obtained by dissolving the gas supplied to the gas supply side 1b in the ultrapure water supplied through the gas permeable membrane 2 is sent to the cleaning tank 5 by the cleaning liquid supply pipe 9, and the gas dissolving device 1 The excess gas dissolved in the ultrapure water is transferred to the gas processing device 6 by the excess gas discharge pipe 10 and processed.

The ultrapure water production device 3 includes a pretreatment device for treating raw water with a coagulating sedimentation device, a sand filtration device, and an activated carbon filtration device, and a reverse osmosis membrane device, a two-bed, three-column ion exchange device. , A mixed-bed ion exchange device, a primary-pure water production device that obtains primary purified water by processing with a precision filter, and a primary-purified water that is subjected to ultraviolet irradiation, a mixed-bed polisher, and an ultrafiltration membrane treatment. A secondary pure water producing apparatus for removing fine particles, colloidal substances, organic substances, metal ions, anions and the like remaining in the apparatus is provided, and a degassing apparatus is further provided if necessary (neither is shown). .

The ultrapure water produced by the ultrapure water production apparatus 3 is used for coagulating sedimentation, filtration, coagulation filtration, activated carbon treatment and the like of raw water such as industrial water, clean water, well water, river water, lake water and the like. By treating with a pretreatment device, coarse suspended substances and organic matter in the raw water are removed, and then treated with a primary pure water production device mainly including a desalination device such as an ion exchange device and a reverse osmosis membrane device. By removing most of impurities such as fine particles, colloidal substances, organic substances, metal ions, anions, etc., this primary pure water is equipped with an ultraviolet irradiation device, mixed bed polisher, ultrafiltration membrane and reverse osmosis membrane Circulating treatment in a secondary pure water production device consisting of a membrane treatment device
High-purity pure water from which impurities such as colloidal substances, organic substances, metal ions, and anions have been removed as much as possible. Examples of the water quality include electric resistivity of 17.0 MΩ · cm or more and total organic carbon of 100 μgC / 1 liter or less, the number of fine particles (particle size 0.07 μm or more) is 50 / ml or less, the number of viable bacteria is 50 / l or less, and silica is 10 μg
SiO ₂ / liter or less, sodium 0.1 μg Na /
Refers to one or less liters. For example, those having the water quality shown in the following Table 1 are preferable, and it is said that if the water quality is ultrapure water, contaminants in the ultrapure water will not adhere to the wafer surface.

[0018]

[Table 1]

As the cleaning function gas dissolved in ultrapure water in the gas dissolving apparatus 1, for example, hydrogen gas, ozone gas, chlorine gas or the like is used. The hydrogen gas, ozone gas, and the like exhibit a cleaning function by being dissolved in ultrapure water, but nitrogen or carbon dioxide gas reacts with, for example, ozone gas dissolved in the cleaning solution to ionize, or in water. It is not preferable that a gas such as nitrogen or carbon dioxide is dissolved in the cleaning solution because the resistivity is lowered by dissociation and ionization. Also, if oxygen is dissolved in ultrapure water, it reacts with hydrogen dissolved in the cleaning solution to generate water (H ₂ O), so that the concentration of dissolved hydrogen decreases and cleaning efficiency decreases. It is also not preferred because Normally, since degassing is performed when ultrapure water is produced by the ultrapure water production device 3, the amount of dissolved gas in the ultrapure water supplied from the ultrapure water production device 3 becomes extremely low. However, before introducing ultrapure water into the gas dissolving apparatus 1, nitrogen, carbon dioxide, oxygen, etc. remaining in the ultrapure water may be further removed by a degassing device (not shown). preferable. In the degassing device, it is preferable to degas so that the total dissolved gas concentration in the ultrapure water supplied to the gas dissolving device 1 is less than 10 ppm, preferably 2 ppm or less. In the degassing apparatus, as a method for degassing the dissolved gas in the ultrapure water, a method of vacuum degassing via a gas permeable membrane is preferable.

When the cleaning gas to be dissolved in ultrapure water in the gas dissolving apparatus 1 is hydrogen gas or ozone gas,
Hydrogen gas generated by ultrapure water electrolysis means and ozone gas generated by oxidizing hydroxyl ions in ultrapure water are preferable because of their high purity. Gas permeable membrane 2 of gas dissolving device 1
Is a hollow fiber membrane as described above. As a method for dissolving a gas in ultrapure water, a cleaning function gas is supplied to the inside of the hollow fiber membrane, and ultrapure water is supplied to the outside to clean the ultrapure water. An external pressure type in which a functional gas is dissolved, an internal pressure type in which ultrapure water is supplied inside the hollow fiber membrane, and a cleaning functional gas is supplied to the outside to dissolve the cleaning functional gas in the ultrapure water, and the like. As the material of the hollow fiber membrane, for example, tetrafluoroethylene resin (PTFE),
Fluorinated resins such as vinylidene fluoride resin (PVDF) and polyolefins are exemplified.

The gas dissolving apparatus 1 of the present invention is characterized in that a hot water supply pipe for cleaning the gas permeable membrane is connected to a conventional gas dissolving apparatus having a gas permeable membrane. When the gas dissolving apparatus 1 of the present invention is provided in a wet processing apparatus, as shown in FIG. 1, an existing ultrapure water supply pipe 7 for supplying ultrapure water from the ultrapure water supply apparatus 3 to the gas dissolving apparatus 1 is used. Is connected to a hot water supply pipe 13 for supplying hot water from a hot water supply device 12 via a switching valve 11a, and a switching valve 11b is connected to an existing gas supply pipe 8 for supplying gas from the gas supply device 4 to the gas dissolving device 1. A hot water supply pipe 13 for supplying hot water from a hot water supply device 12 is connected through the gas permeable membrane 2
It is preferable to supply hot water for cleaning the gas to the gas dissolving apparatus 1. The switching valve 11a is configured to be able to switch between supplying ultrapure water from the ultrapure water supply device 3 and supplying hot water from the hot water supply device 12 to the liquid supply side 1a of the gas dissolving device 1. And switching valve 1
1b is configured to be able to switch between supplying the gas from the gas supply device 4 and supplying the hot water from the hot water supply device 12 to the gas supply side 1b of the gas dissolving device 1.

On the other hand, the exhausted hot water supplied to the gas dissolving apparatus 1 and after the gas permeable membrane 2 has been washed is discharged to the exhausted hot water recovering apparatus 1.
The exhausted hot water discharged from the liquid supply side 1a of the gas dissolving apparatus 1 is connected to the existing cleaning liquid supply pipe 9 via the switching valve 11c, and the exhausted hot water discharged from the liquid supply side 1a of the gas dissolving apparatus 1 The exhausted hot water discharged from the gas supply side 1b of the gas dissolving device 1 is transferred to the exhaust hot water recovery device 14 by connecting the exhaust hot water pipe 15 to the existing surplus gas exhaust pipe 10 via the switching valve 11d. Preferably, it is configured to be transported. The switching valve 11c is configured to be able to switch the connection between the liquid supply side 1a of the gas dissolving apparatus 1 and the cleaning tank 5 or the waste water collecting apparatus 14. The switching of the switching valve 11c causes the cleaning liquid (the cleaning function gas to be dissolved). In the case of ultrapure water, it is transferred to the cleaning tank 5, and in the case of wastewater, the wastewater recovery device 14
Is transferred to Further, the switching valve 11d is a gas dissolving device 1
The connection between the gas supply side 1b and the gas processing device 6 or the exhaust hot water recovery device 14 can be switched. When the surplus gas is transferred by switching the switching valve 11d, the gas is transferred to the gas processing device 6 and discharged. In the case of hot water, it is transferred to the waste water collecting device 14.

As described above, the hot water supply pipe 13 for supplying hot water to the gas dissolving apparatus 1 and the waste hot water after washing the gas permeable membrane 2 of the gas dissolving apparatus 1 are collected by the waste hot water collecting apparatus 14.
It is preferable that the exhaust gas hot water pipe 15 to be transferred to the existing pipe be connected to the existing pipe via a switching valve, because the gas dissolving apparatus of the present invention can be attached by a small processing of the existing equipment.

The apparatus shown in FIG. 1 shows a case where the hot water supplied from the hot water supply apparatus 12 is supplied to both the liquid supply side 1a and the gas supply side 1b of the gas dissolving apparatus 1. Hot water may be supplied to only one of the liquid supply side 1a and the gas supply side 1b,
In this case, it is preferable to supply hot water to the liquid supply side 1. Also, when hot water was supplied to only one of the liquid supply side 1a and the gas supply side 1b, only one side of the gas permeable membrane 2 was washed, and the gas permeable membrane 2 was attached to the surface of the gas permeable membrane 2 on the side where the hot water was not washed. Organic substances and the like are gas permeable membranes 2
There is a possibility that the light may be transmitted to the other surface through the fine holes.
For this reason, a particularly preferred embodiment of the present invention is to supply hot water to both the liquid supply side 1a and the gas supply side 1b of the gas dissolving apparatus 1 as shown in FIG. still,
When configured to supply hot water to only one of the liquid supply side 1a and the gas supply side 1b of the gas dissolving apparatus 1,
The hot water pipe 15 for transferring the hot water to the hot water recovery device 14 may be connected to the hot water supply side (one of the liquid supply side 1a and the gas supply side 1b) of the gas dissolving apparatus 1. .

The gas dissolving apparatus 1 of the present invention can be provided with an ultrasonic generator 16 and is provided with a gas permeable membrane 2 made of hot water.
Irradiation of ultrasonic waves at the time of cleaning can further improve the cleaning effect. The ultrasonic waves emitted from the ultrasonic generator 16 have a frequency of 30 kHz or more.

The method of cleaning the gas permeable membrane 2 by supplying hot water to the gas dissolving apparatus 1 includes a method of cleaning by supplying hot water continuously, and a method of cleaning by supplying intermittently. . Also, as shown in FIG. 1, the ultrapure water supply pipe 7, the gas supply pipe 8, the washing water supply pipe 9, and the surplus gas discharge pipe 10,
Opening / closing valves 17a, 17b, 17c and 17d are provided, respectively, and hot water for cleaning the gas permeable membrane 2 is supplied into the gas dissolving apparatus 1. Then, the opening / closing valves 17a to 17d are closed and hot water is sealed in the gas dissolving apparatus 1. After holding for a certain period of time, the operation of opening the on-off valve and flowing out hot water from the gas dissolving apparatus 1 may be repeated once or twice or more. Further, when cleaning is performed by supplying hot water to both the liquid supply side 1a and the gas supply side 1b of the gas dissolving apparatus 1, even if a method of simultaneously supplying hot water to the liquid supply side 1a and the gas supply side 1b is adopted, A method of alternately supplying hot water to the liquid supply side 1a and the gas supply side 1b may be adopted.

The hot water supplied from the hot water supply device 12 to the gas dissolving device 1 is preferably 45 to 65 ° C. The hot water supply flow rate depends on the size of the gas permeable membrane to be cleaned.
It is preferable to supply continuously at 5 to 5 liters / minute for 5 hours or more. As raw water heated in the hot water supply device 12, ultrapure water is usually used.

Hereinafter, the present invention will be described in more detail with reference to specific examples. Example 1 A gas dissolving apparatus in the wet processing apparatus shown in FIG.
A new gas dissolving membrane module was installed, and the initial value of TOC in this gas dissolving membrane module was set to wet oxidation UV.
It was measured by a TOC meter based on a decomposition method. To measure the TOC initial value, ultrapure water (20 ° C, TO
C: 1.0 ppb) at a flow rate of 2 liter / min.
After a minute, the TOC value in the ultrapure water discharged from the gas dissolving apparatus was set as the TOC initial value. After measuring the TOC initial value, hot water of 60 ° C. (super-pure water heated to 60 ° C.) was passed through the gas dissolving apparatus at a rate of 2 liter / min for 1 hour, and then ultra-pure water at normal temperature (20 ° C.) ) Was flowed at a rate of 2 liters / minute for 1 hour to stabilize, and then the TOC in the ultrapure water discharged from the gas dissolving apparatus was measured (the time during which hot water was flown was defined as the cleaning time, and the time during which the hot water was flown for 1 hour). The washing time is defined as one hour.) Similarly, after flowing hot water for 24 hours, TOC (cleaning time 2
4 hours), 120 hours of flowing hot water, and 1 hour of normal temperature ultrapure water to stabilize the TOC (washing time 120 hours).
Time) was measured. Table 2 shows the results. Hot water was simultaneously supplied from the hot water supply device to the liquid supply side and the gas supply side of the gas dissolving device, and ultrapure water was supplied only to the liquid supply side of the gas dissolving device. The sample measured by the TOC meter is water discharged from the liquid discharge side of the gas dissolving apparatus.

Comparative Example 1 The same treatment as in Example 1 was performed, except that the washing with warm water in Example 1 was replaced with washing with ultrapure water at normal temperature (20 ° C., supply rate 2 liter / min). The results are shown in Table 2. The cleaning time of 1 hour in the case of Comparative Example 1 is the same as that of Example 1 in order to match the conditions with Example 1 after flowing ultrapure water at normal temperature for 1 hour instead of the hot water cleaning of Example 1. The operation of flowing ultrapure water at room temperature for 1 hour was performed, and the actual supply time of ultrapure water was 2 hours. Similarly, when the cleaning time is 24 hours, the actual ultrapure water supply time is 25 hours, and the cleaning time is 1 hour.
In the case of 20 hours, the actual ultrapure water supply time is 121 hours. In Comparative Example 1, a gas dissolving apparatus without a hot water supply apparatus was used, and ultrapure water was supplied only to the liquid supply side of the gas dissolving apparatus.

[0030]

[Table 2]

As is clear from the results shown in Table 2, in Example 1, the TOC value was significantly reduced even with a cleaning time of 1 hour, and the TOC value in the case of performing cleaning for 24 hours was as follows. And the organic matter attached to the gas-dissolved film was practically completely removed. On the other hand, in Comparative Example 1, a high TOC value was exhibited for a cleaning time of 1 hour, and the TOC value was not substantially the same as that of Example 1 for a cleaning time of 24 hours unless cleaning was performed for 120 hours.

Example 2 A gas dissolving apparatus in the wet processing apparatus shown in FIG.
A new gas dissolving membrane module was installed, and the initial value of the concentration of fluorine ions from the gas dissolving membrane module was measured by ion chromatography. The initial value of the fluorine ion concentration is measured by using a gas dissolving apparatus with ultra-pure water (20
° C, TOC: 1.0 ppb) was flowed at a rate of 2 liter / min, and after 5 minutes, the concentration of fluorine ions in the ultrapure water discharged from the gas dissolving apparatus was measured and set as an initial value. After measuring the initial value of the fluorine ion concentration, hot water at 60 ° C. (heated to ultra-pure water at 60 ° C.) was passed through the gas dissolving apparatus at a rate of 2 liters / minute for 1 hour. (20 ° C.) for 1 hour at a flow rate of 2 liters / minute for stabilization, and then the fluorine ion concentration in the ultrapure water discharged from the gas dissolving apparatus was measured (the time during which hot water was flown was defined as the cleaning time, Washing time is 1 hour when warm water is flown for 1 hour). In the same manner, after flowing hot water for 24 hours, fluorine ion concentration (cleaning time: 24 hours) after stabilizing by flowing ultrapure water at room temperature for 1 hour, flowing hot water for 120 hours, and then ultrapure water at room temperature. Was flowed for 1 hour to stabilize, and the fluorine ion concentration (washing time: 120 hours) was measured. Table 3 shows the results.
Hot water was simultaneously supplied from the hot water supply device to the liquid supply side and the gas supply side of the gas dissolving device, and ultrapure water was supplied only to the liquid supply side of the gas dissolving device.

Comparative Example 2 The same treatment as in Example 2 was performed, except that the washing with warm water in Example 2 was replaced with washing with ultrapure water at normal temperature (20 ° C., supply rate 2 liter / min). The results are shown in Table 3. The cleaning time of 1 hour in the case of Comparative Example 2 is the same as that of Example 2 in order to match the conditions with Example 2 after flowing ultrapure water at normal temperature for 1 hour instead of the hot water cleaning of Example 2. The operation of flowing ultrapure water at room temperature for 1 hour was performed, and the actual supply time of ultrapure water was 2 hours. Similarly, when the cleaning time is 24 hours, the actual ultrapure water supply time is 25 hours, and the cleaning time is 1 hour.
In the case of 20 hours, the actual ultrapure water supply time is 121 hours. In Comparative Example 2, a gas dissolving apparatus without a hot water supply apparatus was used, and ultrapure water was supplied only to the liquid supply side of the gas dissolving apparatus.

[0034]

[Table 3]

As is evident from the results shown in Table 3, in Example 2, the fluorine ion concentration was significantly reduced even with a cleaning time of 1 hour, and 0.5 ppb was obtained after cleaning for 24 hours.
It decreased to below, and no outflow of fluorine ions from the gas dissolving membrane was observed. On the other hand, in Comparative Example 2, although the fluorine ion concentration was lower than the initial value at the cleaning time of 1 hour, the value was still considerably high, and even after the cleaning for 24 hours, the value was almost the same as the value after the cleaning for 1 hour. There was no.
In Comparative Example 2, the fluorine ion concentration was 0.5 pp by washing.
It was necessary to wash for 120 hours until the value became b or less.

[0036]

As described above, the gas dissolving apparatus of the present invention is provided with the hot water supply pipe for cleaning the gas permeable membrane, and can supply hot water to the gas dissolving apparatus to clean the gas permeable membrane. As compared to conventional gas dissolving equipment that can only clean with ultrapure water at room temperature, organic substances, dust, bacteria, etc. adhering to the gas permeable membrane can be washed and removed in a short time, and the gas permeable membrane can be cleaned. Even in the case of using a fluororesin, unreacted fluorine ions in the constituent material of the gas permeable membrane can be washed and removed in a short time. If hot water is supplied to both the liquid supply side and the gas supply side of the gas dissolving device, both sides of the gas permeable membrane can be cleaned, and only the liquid supply side of the gas permeable membrane is made of ultrapure water. As in the case of the conventional apparatus that only performs cleaning, there is no possibility that organic substances and the like adhering to the surface of the gas permeable membrane that has not been cleaned are permeated to the cleaning surface side, and more effective cleaning is performed. It can be performed.

Further, when the present invention is used as a gas dissolving apparatus in an existing wet processing apparatus or the like, a hot water supply pipe for supplying hot water to the gas dissolving apparatus is connected to an existing ultrapure water supply pipe or gas supply pipe. If connected via a switching valve, and a drained hot water pipe for transferring the hot water after washing to the drained hot water recovery device is connected to the existing cleaning liquid supply pipe or excess gas discharging pipe via the switching valve, It can be attached to an existing device with only a small amount of processing, and the cost of attachment can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of a configuration of a wet processing apparatus provided with a gas dissolving apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas dissolving apparatus 1a Liquid supply side 1b Gas supply side 2 Gas permeable membrane 3 Ultrapure water supply apparatus 4 Gas supply apparatus 5 Cleaning tank 6 Gas treatment apparatus 7 Ultrapure water supply pipe 8 Gas supply pipe 9 Cleaning liquid supply pipe 10 Excess gas Discharge pipe 11a Switching valve 11b Switching valve 11c Switching valve 11d Switching valve 12 Hot water supply device 13 Hot water supply pipe 14 Waste water collection device 15 Waste water pipe 16 Ultrasonic wave generator

Claims (9)

[Claims] 1. A gas dissolving apparatus for dissolving a gas supplied through a gas permeable membrane into a liquid, wherein the apparatus is provided with a hot water supply pipe for cleaning the gas permeable membrane. Gas dissolving equipment. 2. A gas dissolving device having a gas supply side and a liquid supply side partitioned by a gas permeable membrane, wherein a gas supply pipe for supplying gas from the gas supply device is provided on the gas supply side. An excess gas discharge pipe for sending excess gas to the gas processing apparatus, and an ultrapure water supply pipe for supplying ultrapure water from the ultrapure water supply apparatus to the liquid supply side; 2. A cleaning liquid supply pipe for transferring a cleaning liquid obtained by dissolving gas supplied from the gas supply device to water through a gas permeable membrane to a cleaning tank is connected. Gas dissolving equipment. 3. A hot water supply pipe for cleaning the gas permeable membrane is connected to a gas supply pipe for supplying gas to the gas dissolving device, via a switching valve for switching between a gas supply side and a hot water supply side. The gas dissolving apparatus according to claim 2, wherein: 4. A waste water pipe for guiding the waste water discharged from the gas supply side of the gas dissolving device to the waste water recovery device after cleaning the gas permeable membrane, and a surplus water line for sending surplus gas to the gas treatment device. 4. The gas dissolving apparatus according to claim 3, wherein the gas dissolving apparatus is connected to the gas exhaust pipe via a switching valve for switching between the gas processing apparatus side and the waste water collecting apparatus side. 5. A hot water supply pipe for cleaning a gas permeable membrane is provided in the middle of an ultrapure water supply pipe for supplying ultrapure water to a gas dissolving apparatus, and is connected to an ultrapure water supply apparatus side and a hot water supply apparatus side. 3. The gas dissolving apparatus according to claim 2, wherein the gas dissolving apparatus is connected via a switching valve that switches between the two. 6. A cleaning liquid supply pipe for transferring a cleaning liquid to a cleaning tank, wherein the drain water pipe for guiding the discharged hot water discharged from the liquid supply side of the gas dissolving apparatus to the discharged hot water recovery apparatus after cleaning the gas permeable membrane. 6. The gas dissolving device according to claim 5, wherein the gas dissolving device is connected via a switching valve for switching between the cleaning tank side and the waste water collecting device side. 7. A hot water supply pipe for cleaning the gas permeable membrane is connected to a gas supply pipe for supplying a gas to the gas dissolving device via a switching valve for switching between a gas supply side and a hot water supply side. And a connection between the ultrapure water supply pipe for supplying ultrapure water to the gas dissolving apparatus and a switching valve for switching between the ultrapure water supply apparatus side and the hot water supply apparatus side. 3. The gas dissolving apparatus according to claim 2, wherein 8. A waste water pipe for guiding waste water discharged from the gas supply side of the gas dissolving device, which has washed the gas permeable membrane, to a waste water recovery device, and an excess pipe for sending excess gas to the gas treatment device. In the middle of the gas discharge pipe, it is connected via a switching valve that switches between the gas processing device side and the waste hot water recovery device side, and the waste hot water discharged from the liquid supply side of the gas dissolving device is connected to the waste hot water recovery device. 8. The drainage hot water pipe for guiding is connected to the cleaning liquid supply pipe for transferring the cleaning liquid to the cleaning tank via a switching valve for switching between the cleaning tank side and the waste hot water recovery device side. Gas dissolving equipment. 9. The gas dissolving apparatus according to claim 1, wherein the gas dissolving apparatus includes an ultrasonic generator.