JP2007000699A - Production method of nitrogen gas-dissolved water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of nitrogen gas-dissolved water by which nitrogen gas-dissolved water used for a wet washing process in industries handling electronic materials like semiconductors or liquid crystals can be produced efficiently and economically by reducing an amount of nitrogen used. <P>SOLUTION: In this production method of nitrogen gas-dissolved water by dissolving nitrogen gas in ultra-pure water, the ultrapure water is subjected to deoxidation treatment by a palladium catalyst. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing nitrogen gas-dissolved water. More specifically, the present invention relates to nitrogen gas-dissolved water used in a wet cleaning process performed in an industry that handles electronic materials such as semiconductors and liquid crystals, reducing the amount of nitrogen gas used efficiently and economically. The present invention relates to a method for producing nitrogen gas-dissolved water that can be produced.

  Conventionally, fine water, colloidal substances, organic substances, metals, as cleaning water for objects to be cleaned such as electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, quartz substrates for photomasks, etc. Ultrapure water from which anions and the like are removed as much as possible is used.

  Ultrapure water generally treats raw water such as industrial water, well water, surface water, and wastewater with an ultrapure water production system that consists of a pretreatment device, a primary pure water device, and a secondary pure water device. Produced. FIG. 7 is an example of a process flow diagram of the ultrapure water production apparatus. In the pretreatment device, turbidity of the raw water is performed using a coagulation sedimentation device, a pressurized flotation device, a sand filtration device, a membrane filtration device, or the like. Next, in the primary pure water device, the activated carbon filtration device, the reverse osmosis membrane device, the ion exchange device, the electric desalination device, the deaeration device, the microfiltration membrane device, the oxidation treatment device, etc. are used in any order, and the pretreated water Dissolved impurities such as ions, organic substances and gases are removed. Furthermore, in the secondary pure water device (subsystem), using ultra-violet irradiation device, mixed bed polisher, membrane treatment device such as ultrafiltration membrane device and reverse osmosis membrane device, etc. Impurities such as residual fine particles, colloidal substances, organic substances, metals, and ions are removed to obtain ultrapure water. At the point of use, unused pure water, diluted waste water, and concentrated waste water are collected separately, and pure water and diluted waste water are circulated and re-purified, and the concentrated waste water is treated with waste water.

  Examples of the degassing apparatus used in the ultrapure water production apparatus include vacuum degassing, membrane degassing, nitrogen degassing, heat degassing, catalyst resin degassing, and combinations thereof. By deaeration, dissolved oxygen (DO) is mainly removed from ultrapure water or water in the process of producing ultrapure water. Usually, in vacuum degassing and membrane degassing often used as a degassing apparatus, various dissolved gases dissolved together with dissolved oxygen are also removed. In addition, although the bicarbonate ion and carbonate ion in water can be removed as carbon dioxide gas by deaeration, a decarboxylation tower may be provided separately from these deaeration devices. The ultrapure water produced by such an ultrapure water production apparatus can be used as it is or by dissolving various gases such as ozone gas, hydrogen gas, carbon dioxide gas, nitrogen gas, etc. Used as cleaning water and rinse water for electronic materials such as substrates.

  Removing foreign matters such as fine particles from the surface of the electronic material is extremely important for ensuring product quality and yield. In the case of ultrasonic cleaning of electronic materials and the like, it has been found that a good cleaning effect can be obtained by using cleaning water in which a gas is dissolved. In general, the higher the dissolved gas concentration, the better. However, when it becomes supersaturated, excessive bubbles are generated, which interferes with ultrasonic wave propagation and adheres to the surface of the object to be cleaned, causing uneven cleaning. . Ultrasonic cleaning using cleaning water in which hydrogen gas is dissolved is the most effective for removing fine particles, but nitrogen gas-dissolved water in which nitrogen gas is dissolved is often used because of easy gas handling. It was.

  After completely removing the dissolved gas in the raw water by degassing treatment, the gas permeable membrane module is used to supply and dissolve only the required amount of a specific gas, thereby dissolving the water having a predetermined concentration of gas dissolved in the raw water, It can be manufactured without generating bubbles. FIG. 8 is a process flow diagram of an example of a conventional apparatus for producing nitrogen gas dissolved water. The ultrapure water pumped out from the ultrapure water tank 22 by the pump 23 completely removes the dissolved gas in the membrane deaerator 24, dissolves a predetermined amount of nitrogen gas in the membrane gas dissolver 25, and has a predetermined concentration. Nitrogen gas-dissolved water is produced.

  When cleaning electronic materials such as silicon substrates for semiconductors and glass substrates for liquid crystals, a vacuum degassing tower is used in the deoxygenation process of the ultrapure water production apparatus in the previous stage, or the gas phase side of the degassing film is removed by a vacuum pump or the like Deoxygenation was performed by a method such as decompression and replacement with nitrogen gas to obtain raw water of functional water such as nitrogen gas-dissolved water. Conventionally, the ultrapure water production process and the functional water production process, such as desalting and deoxygenation, have been studied as independent processes, and have been rarely studied from the viewpoint of economy as a whole.

  INDUSTRIAL APPLICABILITY The present invention can efficiently and economically manufacture nitrogen gas-dissolved water used in a wet cleaning process performed in an industry that handles electronic materials such as semiconductors and liquid crystals by reducing the amount of nitrogen gas used. The object of the present invention is to provide a method for producing nitrogen gas-dissolved water.

  As a result of intensive studies to solve the above problems, the present inventor has produced nitrogen gas-dissolved water by using nitrogen gas dissolved in ultrapure water as a nitrogen gas source of nitrogen gas-dissolved water. The amount of nitrogen gas required for the process can be greatly reduced, the size of the nitrogen gas dissolving device can be reduced, and oxygen gas in the ultrapure water can be reduced and removed using a palladium catalyst. It has been found that only oxygen gas can be selectively removed while dissolving nitrogen gas, and the present invention has been completed based on this finding.

That is, the present invention
(1) In a method for producing nitrogen gas-dissolved water by dissolving nitrogen gas in ultra-pure water, the ultra-pure water is ultra-pure water that has been subjected to deoxygenation treatment with a palladium catalyst. Manufacturing method,
(2) The method for producing nitrogen gas-dissolved water according to (1), wherein deoxygenation treatment with a palladium catalyst is performed on ultrapure water produced by an ultrapure water production apparatus;
(3) The method for producing nitrogen gas-dissolved water according to (1), wherein the deoxidation treatment with a palladium catalyst is performed as one step in the ultrapure water production apparatus,
(4) The method for producing nitrogen gas-dissolved water according to any one of (1) to (3), wherein a deoxygenation process is further performed on the downstream side of the deoxygenation process using a palladium catalyst;
(5) The method for producing nitrogen gas-dissolved water according to (4), wherein the deoxygenation treatment in the latter stage is membrane separation,
Is to provide.

  According to the method for producing dissolved nitrogen gas water of the present invention, dissolved nitrogen gas dissolved water used in a wet cleaning process of electronic materials such as a semiconductor silicon substrate, a liquid crystal glass substrate, and a photomask quartz substrate is dissolved in raw water. By using the nitrogen gas that is being used, the amount of new nitrogen gas used can be reduced, and it can be manufactured efficiently and economically in a short time by using a miniaturized nitrogen gas dissolving apparatus.

  In the method for producing nitrogen gas-dissolved water of the present invention, in the method for producing nitrogen gas-dissolved water by dissolving nitrogen gas in ultra-pure water, the ultra-pure water is an ultra-pure water that has been subjected to deoxidation treatment by a palladium catalyst. is there.

  Depending on the performance of the ultrapure water production apparatus, even if the quality of the obtained ultrapure water should be satisfied by the specific resistance value, it may become ultrapure water with a lot of dissolved oxygen gas. When preparing cleaning water by dissolving a specific gas in such ultrapure water, it is necessary to dissolve the specific gas after removing the dissolved oxygen gas in advance in order to obtain a desired dissolved gas concentration. is there.

In the method for producing nitrogen gas-dissolved water of the present invention, the dissolved oxygen gas in the raw water of the nitrogen gas-dissolved water is removed by performing deoxygenation treatment using a palladium catalyst. In deoxygenation treatment using a palladium catalyst, a hydrogen source is added to the raw water, or the raw water is irradiated with ultraviolet light and brought into contact with the palladium catalyst, so that it is dissolved by a reduction reaction of O ₂ + 2H ₂ → 2H ₂ O. Oxygen gas is removed as water. Examples of the hydrogen source added to the raw water include hydrogen gas, hydrogen gas-dissolved water, and a compound that generates hydrogen such as hydrazine. Conventionally used degassing means such as vacuum degassing and membrane degassing also remove dissolved nitrogen gas in addition to dissolved oxygen gas. According to the method of the present invention, only the dissolved oxygen gas can be selectively removed without removing the dissolved nitrogen gas, and the dissolved nitrogen gas in the raw water can be used as a nitrogen gas source for producing nitrogen gas dissolved water. The amount of nitrogen gas used can be reduced, the nitrogen gas dissolving apparatus can be miniaturized, and the nitrogen gas dissolving time can be shortened. In particular, when the raw water tank is sealed with nitrogen, a large amount of nitrogen gas is dissolved in the raw water, so that the dissolved nitrogen gas can be used as it is. In raw water in equilibrium with the atmosphere at 25 ° C., about 8 mg / L oxygen gas and about 14 mg / L nitrogen gas are dissolved. When deoxygenation is performed by vacuum degassing, the concentration of dissolved nitrogen gas in the obtained deoxygenated water is reduced to about 1 mg / L or less. For this reason, if nitrogen gas-dissolved water is produced using deoxygenated water by vacuum degassing, the amount of necessary nitrogen gas is large and the dissolving device becomes large, which is uneconomical.

  FIG. 1 is a process flow diagram of one embodiment of the method for producing nitrogen gas-dissolved water of the present invention. Hydrogen gas is added to the raw water and led to a palladium catalyst tower. Hydrogen gas can also be injected directly into the palladium catalyst tower. Most of the dissolved oxygen gas is removed in the palladium catalyst tower, and deoxygenated water having a dissolved oxygen gas concentration of about 50 to 100 μg / L is obtained. The deoxygenated water is sent to a secondary pure water device and processed by an ultraviolet irradiation device, a mixed bed polisher, a membrane processing device or the like to become ultrapure water. In addition to being sent to the use point as it is, the ultrapure water is sent to the nitrogen gas dissolving device to dissolve the nitrogen gas, and sent to the use point as nitrogen gas dissolved water.

  In the method of the present invention, deoxygenation treatment with a palladium catalyst can be performed on ultrapure water produced by an ultrapure water production apparatus. FIG. 2 is a process flow diagram of another embodiment of the method of the present invention. Pretreated water that has been subjected to coagulation sedimentation, sand filtration, or the like is processed by an ultrapure water production apparatus including a primary pure water apparatus and a secondary pure water apparatus, and flows out of the apparatus as ultrapure water. In this aspect, since the primary pure water device and the secondary pure water device are not provided with a deoxidation treatment device using a palladium catalyst, the outflowing ultrapure water contains oxygen gas and nitrogen gas in equilibrium with the atmosphere. Is dissolved. Ultrapure water is sent to a palladium catalyst tower, hydrogen gas is injected, and dissolved oxygen gas is reduced and removed as water. The deoxygenated water from which the dissolved oxygen gas has been removed is sent to an ion exchange resin tower and a membrane filtration device. Even if a very small amount of palladium ion is eluted from the palladium catalyst, it can be captured by the ion exchange resin, and fine particles derived from the palladium catalyst, the ion exchange resin and the like can be removed by the membrane filtration device. The purified ultrapure water dissolves nitrogen gas with a nitrogen gas dissolving device to obtain nitrogen gas-dissolved water.

  In the method of the present invention, deoxygenation treatment with a palladium catalyst can be performed as one step in the ultrapure water production apparatus. 3 and 4 are process flow diagrams of another embodiment of the method of the present invention. In the embodiment shown in FIG. 3, the palladium catalyst device is provided in the primary pure water device, and in the embodiment shown in FIG. 4, the palladium catalyst device is provided in the secondary pure water device. In any of these proposals, deoxygenation treatment with a palladium catalyst is performed as a process in the ultrapure water production apparatus, so the ultrapure water flowing out of the ultrapure water production apparatus has a low dissolved oxygen gas concentration, and nitrogen gas is left as it is. Nitrogen gas can be dissolved by sending it to a dissolving device to obtain nitrogen gas-dissolved water.

  In the method for producing nitrogen gas-dissolved water of the present invention, the deoxygenation treatment can be further performed on the downstream side of the deoxygenation treatment using a palladium catalyst. There is no particular limitation on the method of deoxygenation in the latter stage, and examples thereof include chemical deoxygenation using a catalyst and the like, physical deoxygenation by vacuum degassing, membrane separation, and the like. Among these, membrane separation can be preferably used because there is no fear of deoxygenated water contamination and the concentration of dissolved oxygen gas can be efficiently reduced. In the deoxygenation process by membrane separation, a part of the dissolved nitrogen gas in the water is lost, but compared with the case of deoxygenation process only by membrane separation without performing deoxygenation process by palladium catalyst. The loss is much less. By performing membrane separation of deoxygenated water having a dissolved oxygen gas concentration of about 50 to 100 μg / L by deoxygenation treatment with a palladium catalyst, the dissolved oxygen gas concentration can be reduced to about 10 μg / L. Nitrogen gas-dissolved water produced from deoxygenated water having such a low dissolved oxygen gas concentration can be suitably used at a point of use where a nitrogen gas-dissolved water having a low dissolved oxygen gas concentration is required.

The palladium catalyst used in the method for producing nitrogen gas-dissolved water of the present invention is not particularly limited as long as it exhibits a catalytic action for a reduction reaction of O ₂ + 2H ₂ → 2H ₂ O at room temperature and normal pressure. In addition to palladium compounds such as metal palladium, palladium oxide, and palladium hydroxide, a catalyst in which palladium is supported on a carrier such as ion exchange resin, alumina, activated carbon, zeolite, and stainless steel can be given.

  The amount of palladium supported on the palladium-supported catalyst is usually preferably 0.1 to 10% by weight based on the carrier. When an anion exchange resin is used as a carrier, an excellent effect is exhibited with a small amount of palladium supported, and therefore, it can be used particularly suitably. A palladium-supported resin in which palladium is supported on an anion exchange resin can be prepared by filling an anion exchange resin in a reaction tower and passing an acidic solution of palladium chloride through water. Furthermore, by adding a reducing agent such as hydrazine or formalin to the reaction tower and reducing it, a catalyst carrying metal palladium can be obtained.

  There is no restriction | limiting in particular in the shape of a palladium catalyst, For example, any shape, such as a powder form, a granular form, a pellet form, and a net shape, can be used. An appropriate amount of the powdered catalyst can be added to the reaction tank provided in the reaction tank, or the catalyst can be filled in a reaction tower or the like and passed through as a fluidized bed. The granular or pellet-shaped catalyst can be packed in a reaction tower or the like to form a catalyst-packed tower, which can be continuously subjected to water flow treatment. Two or more kinds of palladium catalysts having different shapes and shapes can be mixed and used. A catalyst resin obtained by supporting palladium on a spherical or pellet-shaped anion exchange resin having a particle size of about 0.1 to 3 mm has good handling properties and can be used particularly preferably.

  In the method for producing nitrogen gas-dissolved water of the present invention, nitrogen gas is dissolved in ultrapure water that has undergone deoxidation treatment with a palladium catalyst. There is no restriction | limiting in particular in the melt | dissolution method of nitrogen gas, For example, it can melt | dissolve using a packed tower, a wet wall tower, a plate tower, a spray tower, a scrubber, a bubble tower, a bubble stirring tank, a membrane type gas dissolution apparatus, etc. Among these, a membrane gas dissolving apparatus can be used suitably. Since the membrane gas dissolution apparatus has an air chamber and a water chamber partitioned by a gas permeable membrane, the amount of nitrogen gas supplied to the air chamber is adjusted based on the measured value of the air chamber pressure, and the pressure of the air chamber Is maintained at the set value, nitrogen gas-dissolved water in which nitrogen gas having a predetermined concentration is dissolved can be stably produced.

  FIG. 5 is a process flow diagram of one embodiment of the nitrogen gas dissolving apparatus used in the method of the present invention. The ultrapure water that has undergone the deoxygenation treatment is sent to a membrane gas dissolving apparatus 1 having an air chamber and a water chamber partitioned by a gas permeable membrane. The membrane gas dissolving apparatus is provided with a nitrogen gas supply pipe 2 for supplying nitrogen gas to the air chamber and a pressure gauge 3 for measuring the pressure of the air chamber. In the membrane gas dissolving apparatus, the nitrogen gas permeates through the gas permeable membrane and dissolves in the ultrapure water that has undergone the deoxygenation treatment, and the nitrogen gas dissolved water is discharged from the discharge pipe 4. The measured value of the pressure gauge is sent to the controller 5 as a signal, the difference from the set value is automatically calculated in the controller, the signal is sent to the valve 6, and the supply amount of nitrogen gas is adjusted by the opening of the valve. The room pressure is maintained at the set value.

When the air chamber of the membrane gas dissolving apparatus is filled with nitrogen gas and the pressure is 0 kPa (gauge pressure) which is the standard atmospheric pressure, the dissolved nitrogen gas concentration of the nitrogen gas dissolved water becomes a saturated concentration. For example, when the temperature is 25 ° C. and the atmospheric pressure is 101.3 kPa, nitrogen gas-dissolved water in which 17.6 mg / L of nitrogen gas is dissolved is obtained. If the air chamber is completely evacuated and the pressure is -101.3 kPa (gauge pressure), the concentration of dissolved nitrogen gas discharged from the water chamber is 0 mg / L. Assuming that the saturated solubility of nitrogen gas in water at a temperature of t ° C. is α _t mg / L, the pressure of the air chamber of the membrane gas dissolution apparatus is x times (0 ≦ x ≦ 1) −101.3 kPa (gauge pressure). Then, the dissolved nitrogen gas concentration of the nitrogen gas dissolved water discharged from the nitrogen gas dissolved water discharge pipe is α _t (1-x) mg / L. By utilizing this relationship and supplying nitrogen gas so that the pressure of the air chamber becomes a set value, nitrogen gas-dissolved water having a predetermined dissolved nitrogen gas concentration can be produced.

  According to the apparatus of this aspect, the dissolved oxygen gas that has been subjected to deoxygenation treatment is dissolved by adjusting the pressure of the air chamber of the membrane gas dissolving apparatus filled with nitrogen gas to maintain the set value. Even if the nitrogen gas concentration varies, it is possible to stably produce nitrogen gas-dissolved water having a predetermined dissolved nitrogen gas concentration. In the conventional method of performing the degassing process before the nitrogen gas dissolving step, once the nitrogen gas dissolved in the raw water is removed, the necessary amount of nitrogen gas is dissolved. Since ultrapure water that has undergone deoxidation treatment is dissolved only by nitrogen gas as a dissolved gas, by utilizing it without removing it, the production system for dissolved nitrogen gas is simplified, Gas can be used without waste.

  In the apparatus shown in FIG. 5, a gas discharge pipe 7 is provided in the air chamber of the membrane gas dissolving apparatus, and a valve 8 and a pump 9 are provided in the gas discharge pipe. The gas discharge pipe can be used for discharging a gas mixed with air when nitrogen is fed into the air chamber and the internal air is replaced with nitrogen when starting the operation of the apparatus. In addition, if the dissolved nitrogen gas concentration of the nitrogen gas dissolved water to be produced is lower than the dissolved nitrogen gas concentration of ultrapure water that has been subjected to deoxygenation treatment, the nitrogen gas extracted through the gas permeable membrane Can be used to discharge

  When the dissolved nitrogen gas concentration of the nitrogen gas dissolved water to be produced is lower than the dissolved nitrogen gas concentration of the ultrapure water subjected to the deoxygenation treatment supplied, the pressure of the air chamber of the membrane gas dissolving device is nitrogen gas Increased when dissolved water is produced. At this time, the measured value of the pressure gauge 3 is sent to the controller 5 as a signal, the difference from the set value is automatically calculated in the controller, and the signal is sent to the valve 8 to open the valve, thereby reducing the nitrogen gas discharge amount. The pressure in the air chamber is adjusted and the set value is maintained. The downstream side of the valve 8 is maintained at atmospheric pressure or lower by the pump 9.

  In order to produce nitrogen gas-dissolved water having a constant dissolved nitrogen gas concentration by the apparatus shown in FIG. 5, it is only necessary to install a pressure gauge that measures the pressure of the air chamber of the membrane gas dissolver, Since the pressure gauge is installed in the air chamber, there is no need to measure the dissolved nitrogen gas concentration using the sample water, and no branch pipe is required to collect the sample water. Can do. Furthermore, since only the pressure is measured, a complicated operation such as measurement of the nitrogen gas concentration by a densitometer is not required, and no drainage is generated.

  In the apparatus of the embodiment shown in FIG. 5, when ultrapure water that has been subjected to deoxygenation treatment is used as raw water, no gas other than nitrogen gas is dissolved, and the pressure measured by the pressure gauge is immediately reduced to nitrogen gas dissolved water. Corresponding to the dissolved nitrogen gas concentration, the dissolved nitrogen gas concentration of the nitrogen gas dissolved water can be accurately controlled. In addition, since the nitrogen gas supplied to the air chamber of the membrane gas dissolving apparatus is usually a gas having a purity of 100% by volume, the measured pressure value corresponds to the dissolved nitrogen gas concentration. In other words, in order to use ultrapure water that has undergone deoxygenation treatment as raw water and to use a gas with a purity of 100% by volume as the nitrogen gas to be supplied, by measuring the pressure in the air chamber, a predetermined dissolved nitrogen gas concentration The nitrogen gas-dissolved water can be produced.

  There are no particular restrictions on the material of the gas permeable membrane used in the membrane gas dissolving apparatus, for example, polypropylene, poly (4-methylpentene-1), poly (2,6-dimethylphenylene oxide), polydimethylsiloxane, polycarbonate-poly Examples thereof include a dimethylsiloxane block copolymer, a polyvinylphenol-polydimethylsiloxane-polysulfone block copolymer, polytetrafluoroethylene, and polyimide. In the method of the present invention, non-corrosive nitrogen gas is dissolved, and therefore, a polyolefin-based gas permeable membrane such as polypropylene and poly (4-methylpentene-1) can be preferably used. In the membrane gas dissolving apparatus, the type of the gas permeable membrane is not particularly limited, and examples thereof include a flat membrane, a tube type, a spiral, a hollow fiber, a monolith type, a bath immersion type, and a rotating disk membrane.

  In the method of the present invention, it is preferable to supply the ultrapure water and nitrogen gas subjected to the deoxygenation treatment to the membrane gas dissolving apparatus by a countercurrent system. That is, ultrapure water is supplied to one end in the length direction of the membrane of the water chamber of the membrane gas dissolving apparatus, and nitrogen gas dissolved water is discharged from the other end, whereas nitrogen gas is nitrogen gas in the air chamber. It is preferable to supply from the dissolved water discharge side and to discharge from the ultrapure water supply side. By bringing the ultrapure water and nitrogen gas into countercurrent contact, good gas dissolution efficiency can be obtained.

  FIG. 6 is an explanatory view of one embodiment of a membrane gas dissolving apparatus used in the method of the present invention. In this embodiment, a hollow fiber membrane gas dissolving device 10 is used as the membrane gas dissolving device, nitrogen gas is supplied to the inside of the hollow fiber membrane 11, and deoxygenation treatment is applied to the outside of the hollow fiber membrane. Water is supplied. A gas supply chamber 12 is provided at one end of the membrane gas dissolving apparatus, and a gas discharge chamber 13 is provided at the other end via partition plates 14 and 15, and hollow fibers are opened to the gas supply chamber and gas discharge chamber through the partition plates. is doing. A nitrogen gas supply pipe 18 is connected to the gas supply chamber from the nitrogen gas source 16 via the flow rate control valve 17. A gas discharge pipe 19 is connected to the gas discharge chamber. The pressure in the gas discharge chamber is measured by the pressure gauge 20, the measured value of the pressure gauge is sent as a signal to the controller 21, the difference from the set value is automatically calculated in the controller, and the signal is sent to the flow control valve. The supply amount of nitrogen gas is adjusted by the opening of the valve, and the pressure inside the hollow fiber membrane is maintained at a set value.

  In the apparatus of the embodiment shown in FIG. 6, there is no particular limitation on the pressure gauge installed in the air chamber of the membrane gas dissolving apparatus. For example, a liquid column type pressure such as a U-tube type, a single tube type, a null method type, etc. An elastic body type or force balance type pressure gauge such as a meter, a Prudon tube type, a bellows type, or a diaphragm type, a bell type pressure gauge such as a single bell type or a double bell type.

  In the membrane gas dissolving apparatus, the nitrogen gas supply amount adjusting means is not particularly limited. For example, the nitrogen gas supply is performed manually or automatically so that the measured pressure value becomes a set value corresponding to a predetermined dissolved nitrogen gas concentration. The amount can be adjusted. When adjusting the nitrogen gas supply amount automatically, the measured pressure value is input to the calculation device, compared with the set pressure value, and a signal corresponding to the difference is sent to the nitrogen gas supply amount adjusting means. The supply amount can be adjusted. Examples of the means for adjusting the supply amount of nitrogen gas include a flow rate adjustment valve provided in a nitrogen gas supply pipe or a nitrogen gas discharge pipe. In the case of manual operation, the opening of the valve can be adjusted manually.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
Deoxygenation treatment with a palladium catalyst of demineralized water flowing out from the reverse osmosis membrane demineralizer of the ultrapure water production apparatus was performed. The amount of demineralized water was 100 m ³ / h, the dissolved oxygen gas concentration was 8,550 μg / L, and the dissolved nitrogen gas concentration was 13.5 mg / L.
This demineralized water was passed through a catalytic reaction tower having a diameter of 1,000 mm and a height of 4,600 mm packed with 2,000 L of a palladium-supported anion exchange resin [Bayer, Lewatit OC]. h was injected. The dissolved oxygen gas concentration of deoxygenated water flowing out from the catalytic reaction tower was 50 μg / L, and the dissolved nitrogen gas concentration was 13.5 mg / L.
This deoxygenated water was passed through a mixed bed ion exchange resin tower and once stored in a sub tank. 80 m ³ / h of deoxygenated water was extracted from the sub tank, passed through a non-regenerative pure water device [Kurita Kogyo Co., Ltd., Deminer] and an ultrafiltration membrane device, and used as ultrapure water at the point of use. Further, 20 m ³ / h of deoxygenated water was extracted from the sub tank, and water was passed through the nitrogen gas dissolving membrane apparatus while supplying 12.8 g / h of nitrogen gas, thereby producing nitrogen gas dissolved water. The dissolved nitrogen gas concentration of the obtained nitrogen gas-dissolved water was 14.14 mg / L. The obtained nitrogen gas-dissolved water was used at the point of use as functional water.

Comparative Example 1
The deionized water having a dissolved oxygen gas concentration of 8,550 μg / L and a dissolved nitrogen gas concentration of 13.5 mg / L flowing out from the reverse osmosis membrane desalting apparatus of the same ultrapure water production apparatus as in Example 1 was mixed with a mixed bed ion exchange resin. After passing through the tower, water was passed through a degassing membrane device to perform deoxygenation treatment. The dissolved oxygen gas concentration of deoxygenated water flowing out from the degassing membrane device was 50 μg / L, and the dissolved nitrogen gas concentration was 0.677 mg / L.
The obtained deoxygenated water was once stored in the sub tank. 80 m ³ / h of deoxygenated water was extracted from the sub tank, passed through a non-regenerative pure water device [Kurita Kogyo Co., Ltd., Deminer] and an ultrafiltration membrane device, and used as ultrapure water at the point of use. Further, 20 m ³ / h of deoxygenated water was extracted from the sub tank, and water was passed through the nitrogen gas dissolving membrane apparatus while supplying 269 g / h of nitrogen gas, thereby producing nitrogen gas dissolved water. The dissolved nitrogen gas concentration of the obtained nitrogen gas-dissolved water was 14.14 mg / L. The obtained nitrogen gas-dissolved water was used at the point of use as functional water.

Example 2
The deoxygenation treatment by the palladium catalyst of the demineralized water flowing out from the reverse osmosis membrane demineralizer of the ultrapure water production device and the deoxygenation treatment by the degassing membrane device were continued. Water of demineralized water is 100 m ³ / h, dissolved oxygen gas concentration is 8,550μg / L, concentration of dissolved nitrogen gas was 13.5 mg / L.
This demineralized water was passed through the catalytic reaction tower filled with the same palladium-supported anion exchange resin as in Example 1, and 130 g / h of hydrogen gas was injected into the catalytic reaction tower. The dissolved oxygen gas concentration of the primary deoxygenated water flowing out from the catalytic reaction tower was 50 μg / L, and the dissolved nitrogen gas concentration was 13.5 mg / L.
This primary deoxygenated water was passed through a mixed bed ion exchange resin tower and further passed through a degassing membrane device. The dissolved oxygen gas concentration of the secondary deoxygenated water flowing out from the degassing membrane device was 10 μg / L, and the dissolved nitrogen gas concentration was 10.5 mg / L. The obtained secondary deoxygenated water was once stored in the sub tank. Secondary deoxygenated water 80m ³ / h is extracted from the sub tank, and passed through a non-regenerative pure water device [Kurita Kogyo Co., Ltd., Deminer] and an ultrafiltration membrane device. Ultrapure water with particularly low dissolved oxygen gas concentration Used at required use points. Further, secondary deoxygenated water 20 m ³ / h was extracted from the sub tank, and water was passed through the nitrogen gas-dissolving membrane device while supplying 72.8 g / h of nitrogen gas, thereby producing nitrogen gas-dissolved water. The dissolved nitrogen gas concentration of the obtained nitrogen gas-dissolved water was 14.14 mg / L. The obtained nitrogen gas-dissolved water was used at a use point as functional water having a low dissolved oxygen gas concentration.

Comparative Example 2
Deoxygenated water having a dissolved oxygen gas concentration of 10 μg / L was prepared using only a degassed membrane to produce nitrogen gas-dissolved water. The deionized water having a dissolved oxygen gas concentration of 8,550 μg / L and a dissolved nitrogen gas concentration of 13.5 mg / L flowing out from the reverse osmosis membrane desalting apparatus of the same ultrapure water production apparatus as in Example 1 was mixed with a mixed bed ion exchange resin. After passing through the tower, water was passed through a degassing membrane device to perform deoxygenation treatment. The dissolved oxygen gas concentration of deoxygenated water flowing out from the degassing membrane device was 10 μg / L, and the dissolved nitrogen gas concentration was 0.617 mg / L.
The obtained deoxygenated water was once stored in the sub tank. Withdrawn deoxygenated water 80 m ³ / h from the sub tank, non-regenerative pure water device [Kurita Water Industries Ltd., Demina] Rohm & and the ultrafiltration membrane device, low dissolved oxygen gas concentration ultrapure water is required Used at the use point. Further, 20 m ³ / h of deoxygenated water was extracted from the sub tank, and water was passed through the nitrogen gas-dissolving membrane device while supplying 283 g / h of nitrogen gas, thereby producing nitrogen gas-dissolved water. The dissolved nitrogen gas concentration of the obtained nitrogen gas-dissolved water was 14.14 mg / L. The obtained nitrogen gas-dissolved water was used at a use point as functional water having a low dissolved oxygen gas concentration.
The results of Examples 1-2 and Comparative Examples 1-2 are shown in Table 1.

As can be seen from Table 1, the amount of nitrogen gas required to produce nitrogen gas dissolved water having the same dissolved nitrogen gas concentration of 14.14 mg / L is 1/21 of that of Comparative Example 1 in Example 1. It can be seen that the amount of nitrogen gas necessary for producing the nitrogen gas-dissolved water can be greatly reduced by performing the deoxygenation treatment with a palladium catalyst.
In Example 2, the primary deoxygenated water subjected to the deoxygenation treatment using the palladium catalyst was further deoxygenated using the degassing membrane device to obtain the secondary deoxygenated water. In Example 2, only the deoxygenation treatment using the palladium catalyst was performed. Compared to Example 1, the amount of nitrogen gas necessary to produce nitrogen gas-dissolved water having the same dissolved nitrogen gas concentration of 14.14 mg / L is 5.7 times. However, compared with Comparative Example 2 in which deoxygenation treatment was performed only by the degassing membrane device, the amount of nitrogen gas necessary for producing the same dissolved nitrogen gas concentration 14.14 mg / L of nitrogen gas dissolved water was In Example 2, it is 1 / 3.9 of the comparative example 2, and it turns out that the quantity of nitrogen gas required for manufacture of nitrogen gas dissolved water can be reduced by performing a deoxidation process by a palladium catalyst.

  According to the method for producing dissolved nitrogen gas water of the present invention, dissolved nitrogen gas dissolved water used in a wet cleaning process of electronic materials such as a semiconductor silicon substrate, a liquid crystal glass substrate, and a photomask quartz substrate is dissolved in raw water. By using the nitrogen gas that is being used, the amount of new nitrogen gas used can be reduced, and it can be manufactured efficiently and economically in a short time by using a miniaturized nitrogen gas dissolving apparatus.

It is a process flow diagram of one mode of the method of the present invention. It is a process flow diagram of other modes of the method of the present invention. It is a process flow diagram of other modes of the method of the present invention. It is a process flow diagram of other modes of the method of the present invention. It is a process flow diagram of one mode of a nitrogen gas dissolving device used for a method of the present invention. It is explanatory drawing of the one aspect | mode of the membrane type gas dissolving apparatus used for this invention method. It is a process system diagram of an example of an ultrapure water manufacturing apparatus. It is a process system diagram of an example of the manufacturing apparatus of the conventional nitrogen gas dissolved water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane-type gas dissolution apparatus 2 Nitrogen gas supply pipe 3 Pressure gauge 4 Discharge pipe 5 Controller 6 Valve 7 Gas discharge pipe 8 Valve 9 Pump 10 Hollow fiber membrane gas dissolver 11 Hollow fiber membrane 12 Gas supply chamber 13 Gas discharge chamber DESCRIPTION OF SYMBOLS 14 Partition plate 15 Partition plate 16 Nitrogen gas source 17 Flow control valve 18 Nitrogen gas supply pipe 19 Gas exhaust pipe 20 Pressure gauge 21 Controller 22 Ultrapure water tank 23 Pump 24 Membrane deaerator 25 Membrane gas dissolver

Claims (5)

  A method for producing nitrogen gas-dissolved water by dissolving nitrogen gas in ultra-pure water, wherein the ultra-pure water is ultra-pure water that has undergone deoxidation treatment with a palladium catalyst. .   The method for producing nitrogen gas-dissolved water according to claim 1, wherein the deoxygenation treatment with a palladium catalyst is performed on ultrapure water produced by an ultrapure water production apparatus.   The method for producing nitrogen gas-dissolved water according to claim 1, wherein the deoxygenation treatment with a palladium catalyst is performed as one step in the ultrapure water production apparatus.   The method for producing nitrogen gas-dissolved water according to any one of claims 1 to 3, wherein the deoxygenation treatment is further performed on the downstream side of the deoxygenation treatment with a palladium catalyst.   The method for producing nitrogen gas-dissolved water according to claim 4, wherein the deoxygenation treatment in the latter stage is membrane separation.

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