JP2001062454A - Apparatus for production of electrolytic water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a trace amount of decomposable materials included in ultrapure water and to obtain electrolytic water having a high washing effect by bringing the ultrapure water of ultrapure water supply piping into contact with the oxidation reduction catalyst of a catalyst reaction section and filtering the ultrapure water with a filter device, then electrolyzing the ultrapure water with an electrolytic cell. SOLUTION: The ultrapure water is first supplied by a pump 1 to supply piping 2. The supply piping 2 is connected to the catalyst reaction section 3 where the ultrapure water is brought into contact with the oxidation reduction catalyst. The ultrapure water subjected to the catalyst reaction is filtered in the filter device 4. In succession, the ultrapure water is introduced to the electrolytic cell 5 and is electrolyzed. Medicinal liquids, such as acids and alkalis, are injected from a medicinal liquid tank 6 and a chemical injecting pump 7 into the electrolytic water at this time. As a result, the decomposable materials included in the ultrapure water are efficiently removed and the respective decomposition of the oxidizing materials in electrolytic anode water and the reducing materials in the electrolytic cathode water is suppressed and the electrolytic water having the high washing effect is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for producing electrolyzed water. More specifically, the present invention removes a small amount of decomposable substances contained in ultrapure water, suppresses decomposition of oxidizing substances in electrolytic anode water and reducing substances in electrolytic cathodic water, and provides a high cleaning effect of electrolytic solution. The present invention relates to an apparatus for producing electrolyzed water from which water can be obtained.

[0002]

2. Description of the Related Art It is extremely important to remove foreign matter from the surface of electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, and quartz substrates for photomasks, in order to ensure product quality and yield. Wet cleaning is widely performed for the purpose. To remove organic and metal contamination, it is effective to use a cleaning solution that has a strong oxidizing power, such as a mixture of sulfuric acid and hydrogen peroxide (SPM cleaning solution) or a mixture of hydrochloric acid, hydrogen peroxide and ultrapure water. High-temperature cleaning with a liquid (SC2 cleaning liquid) or the like is employed. To remove particulate contamination, a mixed solution of ammonia water, hydrogen peroxide water and ultrapure water (A
High-temperature cleaning using a PM cleaning solution) or the like has been employed. In recent years, simplification of the washing process, resource saving, and room temperature have been demanded, and attention has been paid to electrolytic water that has an extremely low concentration of dissolved substances and is effective in removing contaminants on the surface of electronic materials. It has come to be used for cleaning the surface of electronic materials. When ultrapure water is electrolyzed using an electrolytic cell equipped with an ion exchange membrane or ion exchange resin, these ion exchangers promote the dissociation of water molecules and continuously supply hydrogen ions and hydroxyl ions to the electrodes. On the anode side, oxidizing electrolytic anode water is generated, and on the cathode side, reducing electrolytic cathode water is generated. Electrolytic anode water is effective in removing metal contamination and organic contamination adhering to the surface of electronic materials such as silicon wafers.
It is effective in removing fine particle contamination attached to the electronic material surface. Washing with electrolytic water can be performed at room temperature, and the amount of chemical solution used and the amount of rinse water can be reduced. But,
In the case of cleaning with electrolytic water, there is a case where impurities attached to the surface of the electronic material are not sufficiently removed. Therefore, electrolytic water having a higher cleaning effect has been demanded.

[0003]

SUMMARY OF THE INVENTION The present invention removes a trace amount of decomposable substances contained in ultrapure water and suppresses decomposition of oxidizing substances in electrolytic anode water and reducing substances in electrolytic cathodic water, An object of the present invention is to provide an apparatus for producing electrolyzed water that can obtain electrolyzed water having a high cleaning effect.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, there is a trace substance which reduces the cleaning effect in ultrapure water which is raw water of electrolyzed water. The present inventors have found that this trace substance can be effectively removed by an oxidation-reduction catalyst, and that electrolyzed water produced from ultrapure water from which the trace substance has been removed has a high cleaning effect. Was completed. That is, the present invention provides (1) (A) a ultrapure water supply pipe through which ultrapure water is supplied, and (B) a catalyst reaction section which is connected to the ultrapure water supply pipe to bring the ultrapure water into contact with the oxidation-reduction catalyst. And (C) an apparatus for producing electrolyzed water, comprising: a filtration device for filtering ultrapure water that has passed through the catalytic reaction section; and (D) an electrolysis cell for electrolyzing ultrapure water discharged from the filtration device. Is what you do. further,
In a preferred embodiment of the present invention, (2) the redox catalyst comprises:
2. The apparatus for producing electrolyzed water according to item 1, wherein the apparatus is a palladium-supported resin; (3) the apparatus for producing electrolyzed water according to item 1, wherein the catalyst reaction section for bringing ultrapure water into contact with an oxidation-reduction catalyst is a catalyst packed tower; (4) The apparatus for producing electrolyzed water according to (3), wherein the catalyst-packed tower is a tower filled with a palladium-supported resin and an anion exchange resin or a cation exchange resin in a mixed state or a stacked state. The apparatus for producing electrolyzed water according to claim 3, which is a column packed with a palladium-supported resin, an anion exchange resin, and a cation exchange resin in a mixed state or a stacked state,
(6) The apparatus for producing electrolyzed water according to (3), wherein the catalyst-packed tower has a palladium-carrying resin tower and an anion exchange resin tower or a cation exchange resin tower connected in series in this order.
(7) The apparatus for producing electrolyzed water according to (3), wherein the catalyst-packed tower comprises a palladium-supporting resin tower, a cation exchange resin tower, and an anion exchange resin tower connected in series in this order. 4. The apparatus for producing electrolyzed water according to claim 3, wherein a palladium-supported resin tower, and a mixed bed tower of a cation exchange resin and an anion exchange resin are connected in series in this order.
And (9) the first device, wherein the filtration device includes one of an ultrafiltration membrane (UF), a microfiltration membrane (MF), and a reverse osmosis membrane (RO), or is a device in which these membranes are combined. And an apparatus for producing electrolyzed water described in the section.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The apparatus for producing electrolyzed water of the present invention comprises:
(A) an ultrapure water supply pipe through which ultrapure water is supplied, (B) a catalyst reaction section connected to the ultrapure water supply pipe and bringing the ultrapure water into contact with the oxidation-reduction catalyst, and (C) a catalyst reaction section It has a filtration device for filtering ultrapure water and (D) an electrolysis cell for electrolyzing ultrapure water discharged from the filtration device. The ultrapure water to be treated by the apparatus of the present invention is usually a raw water such as city water or industrial water, which is treated by a pretreatment system including coagulation sedimentation, filtration, and the like, followed by ion exchange, deaeration, and reverse osmosis membrane treatment. And the like, and then a secondary pure water system is used to perform treatments such as ultraviolet oxidation, ion exchange, and ultrafiltration membrane. FIG. 1 is a process flow diagram of one embodiment of the apparatus of the present invention.
In this embodiment, the ultrapure water is supplied to the ultrapure water supply pipe 2 by the ultrapure water supply pump 1. There is no particular limitation on the ultrapure water supply pump, and examples thereof include a piston pump, a plunger pump, a booster pump, a turbine pump, and a volute pump. Among them, a booster pump can be preferably used. In the apparatus of the present invention, the ultrapure water supply pipe 2 is connected to a catalytic reaction section 3 for bringing the ultrapure water into contact with the oxidation-reduction catalyst. The oxidation-reduction catalyst used in the apparatus of the present invention is not particularly limited, and examples thereof include a platinum catalyst, a silver catalyst, and a palladium catalyst. Among them, a palladium catalyst can be particularly preferably used. As the palladium catalyst, besides metal palladium, palladium oxide, palladium hydride, and the like, a catalyst in which palladium is supported on a carrier such as an ion exchange resin, alumina, activated carbon, or zeolite can be used. The shape of the palladium catalyst is not particularly limited, and for example, any shape such as powder, granule, and pellet can be used. The powdery catalyst can be provided with a reaction tank and an appropriate amount can be added to the reaction tank, or can be filled in a reaction tower or the like and subjected to water treatment as a fluidized bed. The granular or pelletized catalyst can be packed in a reaction tower or the like to form a catalyst packed tower, and can be continuously subjected to water flow treatment.

In the case of a supported palladium catalyst, the amount of supported palladium is preferably 0.1 to 10% by weight. Among the palladium-supported catalysts, a palladium-supported resin in which palladium is supported on an anion exchange resin exhibits an excellent effect with a small amount of palladium supported, and thus can be particularly preferably used. The palladium-supported resin in which palladium is supported on an anion exchange resin can be prepared by filling a reaction tower with an anion exchange resin and passing an acidic solution of palladium chloride through water. Furthermore, by reducing the reaction tower by adding a reducing agent such as formalin, a catalyst carrying metal palladium can be obtained. By contacting the ultrapure water with the oxidation-reduction catalyst in the catalytic reaction section, it is possible to remove trace amounts of decomposable substances that promote the decomposition of oxidizing substances and reducing substances in the electrolytic water contained in the ultrapure water. . Examples of trace amounts of decomposable substances that promote the decomposition of oxidizing substances and reducing substances include, for example, OH radicals and H radicals, which are decomposition products of water generated by an ultraviolet irradiation device in an ultrapure water production system. Can be In the device of the present invention, the palladium-carrying resin and the ion-exchange resin can coexist in the catalyst packed tower.
The mode of coexistence of the palladium-supported resin and the ion-exchange resin is not particularly limited.For example, a palladium-supported resin and an anion-exchange resin or a palladium-supported resin and a cation-exchange resin can be filled in a mixed state or a stacked state in a catalyst packed tower. The palladium-carrying resin tower, anion-exchange resin and cation-exchange resin tower can be packed in a mixed state or a stacked state, and the palladium-carrying resin tower and the anion-exchange resin tower or the cation-exchange resin tower are connected in series in this order. It is also possible to connect a palladium-supported catalyst tower, a cation exchange resin tower and an anion exchange resin tower in series in this order, or a palladium-supported catalyst tower and a mixed bed tower of a cation exchange resin and an anion exchange resin. They can be connected in series in order. By coexisting palladium-supported resin and ion-exchange resin, even if a very small amount of palladium ion elutes from the palladium-supported resin, it can be captured by the ion-exchange resin, and ion components elute from the ultrapure water feed pump Even so, it can be captured by the ion exchange resin, and high purity of ultrapure water can be maintained.

[0007] In the apparatus of the present invention, the ultrapure water that has passed through the catalytic reaction section is filtered in the filtration device 4. There is no particular limitation on the filtration membrane used in the filtration device, and examples thereof include an ultrafiltration membrane (UF), a microfiltration membrane (MF), and a reverse osmosis membrane (RO). One of these filtration membranes can be used alone, or two or more can be used in combination. Filtration of ultrapure water using a filtration device removes particles derived from ultrapure water feed pump, palladium-supported resin, cation exchange resin, anion exchange resin, etc., and maintains high purity of ultrapure water can do. In the apparatus of the present invention, ultrapure water discharged from the filtration device is guided to the electrolysis cell 5 to perform electrolysis of the ultrapure water. There is no particular limitation on the form of the electrolytic cell to be used. For example, a two-chamber structure in which an anode chamber and a cathode chamber are separated by one diaphragm, or an anode chamber using two ion exchange membranes can be used. Alternatively, a three-chamber structure in which the cathode chamber and the intermediate chamber are partitioned and the intermediate chamber is filled with an ion exchange resin may be employed. Since the ion exchange membrane and the ion exchange resin promote the dissociation of water molecules and continuously supply H ⁺ ions and OH ^- ions to the electrode, the anode water containing an oxidizing substance containing no oxidizing substance and containing no supporting electrolyte is used. And an electrolytic cathode water containing a reducing substance. The material of the electrode to be used is not particularly limited, but as the anode, for example, platinum, iridium, or those obtained by coating these on a substrate such as titanium can be suitably used, and as the cathode, for example, For example, a material in which platinum is supported on a base material such as stainless steel, aluminum, silver, or carbon or fluororesin can be suitably used. In the apparatus of the present invention, a chemical solution tank 6 and a chemical injection pump 7 are provided, and a chemical solution injection point is provided so that a chemical solution such as an acid or an alkali can be injected into the electrolytic water. Instead of the chemical injection pump, it can be pumped by an inert gas such as nitrogen gas. In the apparatus of the present invention, it is preferable that all the liquid contact portions of the piping of the electrolytic cell and the electrolytic anode water are made of an oxidation-resistant material. Examples of the oxidation-resistant material include a fluorine resin, quartz, and a metal whose surface is passivated. FIG.
It is a process system diagram of another mode of (B) catalyst reaction part of the device of the present invention. In this embodiment, the catalyst packed tower 8 is packed with a palladium-carrying resin layer 9 and a mixed layer 10 of a cation exchange resin and an anion exchange resin in a stacked state in this order.
FIG. 3 is a process system diagram of another embodiment of the catalyst reaction section (B) of the apparatus of the present invention. In this embodiment, the catalyst-packed tower comprises a palladium-carrying resin tower 11 and a mixed-bed tower 12 of a cation exchange resin and an anion exchange resin, both of which are connected in series in this order. In the apparatus of the present invention, a trace amount of decomposable substances that reduce the detergency in the electrolyzed water contained in the ultrapure water are removed, and even when palladium or the like is eluted from the oxidation-reduction catalyst, the ion exchange resin is present. Thus, even if fine particles flow out of the catalytic reaction section, the fine particles can be captured and removed by the filtration device. By using the apparatus for producing electrolyzed water of the present invention, electrolyzed water having an excellent detergency capable of efficiently removing surface contaminants such as electronic materials can be easily produced.

[0008]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 (Removal of fine particles by electrolytic cathode water) A 6-inch silicon wafer with a thermal oxide film was
After being immersed in ultrapure water in which mg / L was dissolved for 3 minutes, the substrate was preliminarily washed by rinsing with ultrapure water for 5 minutes. Then
The silicon wafer was immersed in a solution containing alumina (Al ₂ O ₃ ) particles, thereby forcibly contaminating the silicon wafer. The number of fine particles on the surface of a contaminated silicon wafer can be measured using a surface foreign matter inspection device [
Topcon, WM-1500]
11,019 particles having a diameter of 0.2 to 0.5 μm, 32,179 particles having a diameter of 0.5 to 1.0 μm, and a diameter of 1.0
The number of fine particles having a size of not less than μm was 197. From the ultrapure water supply pipe, specific resistance 18.2 MΩ · cm, TOC concentration 0.9 μg /
L of ultrapure water was passed through a catalyst packed column in which a 1% by weight palladium-supported anion exchange resin and a strongly basic anion exchange resin were mixed and filled at a volume ratio of 1: 9 at a surface speed of the catalyst resin of 900 hr ^-1 . The ultrapure water is obtained by coagulating and sedimenting the raw water, filtering, and then desalting with an ion exchange device and treating the primary pure water obtained by reverse osmosis membrane treatment with ultraviolet oxidation, deaeration, and ultrafiltration membrane treatment. It is a thing. The effluent of the catalyst packed tower is passed through an ultrafiltration device, and the effluent of the ultrafiltration device is passed through an electrolytic ion device [Permelec Electrode Co., Ltd., PEW-200-01] to perform electrolysis. Cathode water was obtained. 5 mg / L of high-purity ammonia water as ammonia was added to the electrolytic cathode water to prepare washing water. 5 above contaminated silicon wafer
Rotating at 00 rpm, washing water was sprayed at a flow rate of 800 mL / min for 180 seconds while irradiating ultrasonic waves with a frequency of 1.6 MHz by an ultrasonic oscillator [Pretec, FINEJET], and washing was performed. It was dried at 1,500 rpm for 20 seconds. The number of fine particles on the silicon wafer surface after drying was 986 fine particles having a diameter of 0.2 to 0.5 μm,
969 fine particles having a diameter of 0.5 to 1.0 μm, and a diameter of 1.0
There were 20 fine particles having a size of at least μm. Comparative Example 1 A contaminated silicon wafer was prepared in the same manner as in Example 1. The number of fine particles on the surface was 10,335 fine particles having a diameter of 0.2 to 0.5 μm and 3 fine particles having a diameter of 0.5 to 1.0 μm.
There were 5,626 particles and 282 particles having a diameter of 1.0 µm or more. A washing water was prepared in the same manner as in Example 1, except that the same ultrapure water as in Example 1 was directly passed through the electrolytic ion apparatus without passing through the catalyst packed tower and the ultrafiltration apparatus.
The above-mentioned contaminated silicon wafer was cleaned. The number of fine particles on the surface of the silicon wafer after drying is 0.2 to 0.5 in diameter.
1,609 micron particles, 2,211 microparticles with a diameter of 0.5 to 1.0 μm, and 4 microparticles with a diameter of 1.0 μm or more
There were zero. Table 1 shows the results of Example 1 and Comparative Example 1.

[0009]

[Table 1]

As can be seen from Table 1, Example 1 in which ultrapure water was contacted with an oxidation-reduction catalyst and then electrolyzed and then washed with electrolytic cathode water obtained was used. Compared with Comparative Example 1 in which cleaning was performed using electrolytic cathode water obtained by performing electrolysis as it was, the number of fine particles after cleaning was smaller, the removal rate of fine particles was higher, and cleaning was performed more effectively. Example 2 (Removal of organic matter by electrolytic anode water) A 6-inch silicon wafer provided with a thermal oxide film was treated with ozone 5
After being immersed in ultrapure water in which mg / L was dissolved for 3 minutes, the substrate was preliminarily washed by rinsing with ultrapure water for 5 minutes. The contact angle of the pre-cleaned silicon wafer to ultrapure water is 2.
It was 0 degrees. The silicon wafer was left in the air overnight for forced contamination. The contact angle of the silicon wafer after the forced contamination to ultrapure water was 62.7 degrees. From the ultrapure water supply pipe, specific resistance 18.2 MΩ · cm, TOC concentration 0.
9 μg / L ultrapure water was added to an anion exchange resin carrying 1% by weight of palladium and a strongly basic anion exchange resin in a volume ratio of 1: 9.
The catalyst resin has a surface velocity of 900
Water was passed at hr ^-1 . Further, the effluent from the catalyst packed tower is passed through an ultrafiltration device, and the effluent from the ultrafiltration device is passed through an electrolytic ion device [Permelec Electrode Co., Ltd., PEW-200-01] to perform electrolysis. Thus, electrolytic anode water was obtained. The above-mentioned contaminated silicon wafer is rotated at 500 rpm, and the electrolytic anode water is sprayed at a flow rate of 800 mL / min for 180 seconds while being irradiated with ultrasonic waves having a frequency of 1.6 MHz by an ultrasonic oscillator [Pretech, FINEJET] for cleaning. Then, the rotation speed was increased to 1,500 rpm and drying was performed for 20 seconds. The contact angle of the dried silicon wafer to ultrapure water was 2.3 degrees. Comparative Example 2 In the same manner as in Example 2, a silicon wafer provided with a thermal oxide film was preliminarily cleaned, and left in the air overnight for forced contamination. The contact angle of the silicon wafer to ultrapure water was 2.1 degrees after pre-cleaning, and 61.2 degrees after forced contamination. Electrolyte anode water was prepared in the same manner as in Example 2, except that the same ultrapure water as in Example 2 was directly passed through the electrolytic ion apparatus without passing through the catalyst packed tower and the ultrafiltration device. Then, the contaminated silicon wafer was cleaned. The contact angle of the dried silicon wafer to ultrapure water is
5.3 degrees. Table 2 shows the results of Example 2 and Comparative Example 2.

[0011]

[Table 2]

As can be seen from Table 2, when the pre-cleaned silicon wafer is left in the air overnight, it is contaminated by organic substances, the surface becomes hydrophobic, and the contact angle increases. In Example 2, in which ultrapure water was contacted with the oxidation-reduction catalyst and then electrolyzed and then washed using electrolytic anode water, the contact angle after the washing was almost returned to the value before the forced contamination, and the organic matter was contaminated. Has been almost completely removed. On the other hand, in Comparative Example 2 in which cleaning was performed using electrolytic anode water obtained by electrolyzing ultrapure water as it was, the contact angle after cleaning was larger than the contact angle before forcible contamination, and organic contamination was completely eliminated. Has not been removed.

[0013]

By using the apparatus for producing electrolyzed water of the present invention, electrolytic cathode water and electrolytic anode water having high detergency can be obtained, and the cleaning effect can be improved without changing the cleaning conditions such as extending the cleaning time. Can be improved.

[Brief description of the drawings]

FIG. 1 is a process flow diagram of one embodiment of the apparatus of the present invention.

FIG. 2 is a process flow diagram of another embodiment of the catalytic reaction section of the apparatus of the present invention.

FIG. 3 is a process flow diagram of another embodiment of the catalytic reaction section of the apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrapure water supply pump 2 Ultrapure water supply pipe 3 Catalytic reaction part 4 Filtration device 5 Electrolysis cell 6 Chemical tank 7 Chemical injection pump 8 Catalyst filling tower 9 Palladium-loaded resin layer 10 Mixed layer of cation exchange resin and anion exchange resin 11 Palladium-loaded resin tower 12 Mixed bed tower of cation exchange resin and anion exchange resin

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 9/00 504 C02F 9/00 504E

Claims (1)

[Claims] (A) ultrapure water supply piping for supplying ultrapure water,
(B) Connected to the ultrapure water supply pipe and brought into contact with the ultrapure water with the oxidation-reduction catalyst; (C) a filtration device that filters ultrapure water passing through the catalyst reaction portion; An electrolytic water producing apparatus, comprising: an electrolytic cell for electrolyzing ultrapure water to be produced.