JP2000263046A - Generator of electrolyzed water for cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generator of electrolyzed water for cleaning, which generates electrolyzed water without metallic impurities and solid fine particles, can work stably even in continuous operation over a long term, and can exchange electrodes easily without interrupting the operation. SOLUTION: A generator of electrolyzed water for cleaning has a plurality of two-chamber type diaphragm electrolytic cell units 2 each of which consists of an anode chamber 3 accommodating an anode and an anode feeder each formed by covering the surface of an expand titanium substrate, which has been subjected to flat processing of smoothness of 10-80%, with an active layer, a solid polymer electrolyte diaphragm, and a cathode chamber 4 accommodating a cathode and a cathode feeder, and it is arranged with piping for water supply and piping for water discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the cleaning of a substrate surface, such as a semiconductor substrate and a liquid crystal display device substrate, which requires a high degree of cleanliness, particularly a substrate surface which is difficult to be etched. The present invention relates to a generator for obtaining electrolyzed water.

[0002]

2. Description of the Related Art Semiconductor substrates, liquid crystal display element substrates, etc.
For cleaning of the substrate surface requiring cleanliness, cleaning based on hydrochloric acid / hydrogen peroxide, ammonia / hydrogen peroxide and dilute hydrofluoric acid has been widely performed. This method is an improvement based on RCA cleaning developed by RCA in the United States for cleaning electron tubes.

[0003] Japanese Patent Application Laid-Open No. Hei 10-1794 discloses a washing method using electrolytic water of acidic water and alkaline water, in which an electrolyte such as hydrochloric acid or ammonia to be supplied is electrolyzed and generated. Acid water and alkaline water are used as washing water for removing metal impurities and solid fine particles.

There are many processes for cleaning the surface of a semiconductor substrate, and both oxidizing and reducing properties are required for the cleaning water. This is very useful in that alkaline washing water, which is an acidic washing water, can be obtained at the same time.

[0005] However, near the final cleaning, it is necessary to clean the exposed metal portion, but the electrolytic water cannot be used due to the problem of etching on the substrate surface.

JP-A-10-286571 discloses a method for electrolyzing ultrapure water using a solid polymer electrolyte (hereinafter abbreviated as "SPE") diaphragm without adding an electrolyte. When the electrolyzed water obtained according to the publication is used for cleaning, cleaning can be performed without etching the substrate surface.

[0007] However, this publication is derived from the electrolysis for ozone generation, and has a problem that although the amount of metal impurities is very small, the SPE diaphragm is damaged by contact with the anode and a large amount of solid fine particles are generated. There is.
Further, when the operation is performed for a long period, elution of metal impurities from the anode becomes a problem.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems by stably operating even a long-term continuous operation and easily stopping the operation even when replacing electrodes. An object of the present invention is to provide an apparatus for generating electrolyzed water for cleaning that can be replaced.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention.

That is, the present invention provides an anode chamber in which an active layer is coated on the surface of an expanded titanium substrate flat-processed to a smoothness of 10 to 80%, an anode chamber containing an anode power supply, a solid polymer electrolyte membrane, a cathode, An apparatus for generating electrolyzed water for cleaning comprising a two-chamber diaphragm electrolyzer unit comprising a cathode chamber accommodating a cathode power supply, and a pipe for supply water and a drainage water, each being provided with a plurality of electrolyzer units. An electrolytic water generating apparatus for washing, characterized in that:

The present invention will be described below in detail with reference to the drawings. FIG. 1 shows an outline of an apparatus for generating electrolytic water for cleaning according to the present invention, in which four two-chamber diaphragm electrolytic cell units are used in parallel.

The apparatus for generating electrolytic water for cleaning according to the present invention comprises an SP
An anode and a cathode, each of which is disposed in close contact with both sides of the E-membrane, a feeder disposed on each of its outer sides, and a tank disposed on each of its outer sides, and the anode is separated by the SPE diaphragm. A plurality of two-chamber diaphragm electrolytic cell units 2 each including a chamber 3 and a cathode chamber 4 are provided.

The SPE membrane is a cation exchange membrane made of Teflon, and one or a plurality of SPE membranes may be used.

The substrate of the anode is an expanded titanium substrate flat-processed to a smoothness of 10 to 80%.
The metal plate that is pulled and formed into a mesh shape is referred to as “smoothness 0%”, and the one obtained by rolling and smoothing the horizontal surface is referred to as “smoothness 100%”.

If the smoothness is less than 10%, the SPE diaphragm will be damaged when it comes into contact with the SPE diaphragm, and if it is more than 80%, outgassing will be poor and disadvantageous.

The step width (also called “strand width”) of the expanded titanium substrate is 0.5 to 2.0 mm,
If the step width is less than 0.5 mm, the strength of the substrate becomes weak. If the step width is more than 2.0 mm, outgassing becomes worse, which is inconvenient.

The anode is made of platinum, platinum oxide, tantalum, tantalum oxide and / or iridium oxide on a surface of an expanded titanium substrate which has been flat-processed to a smoothness of 10 to 80% by any of a firing method, a plating method and a sputtering method. At least one selected from the group consisting of:

An anode in which an active layer is coated on the surface of an expanded titanium substrate flat-processed to a smoothness of 10 to 80%, and S
Even when the PE membrane is brought into contact with the PE membrane, it does not damage the SPE membrane and adheres uniformly, so that it is possible to perform electrolysis at a stable current and voltage, and it is also possible to obtain solids caused by the conventional contact between the anode and the SPE membrane. No fine particles are generated.

The conventional anode derived from the electrolysis for ozone generation is based on point contact, in which the surface of an expanded titanium substrate is subjected to a treatment such as sandblasting and the surface of the substrate is provided with irregularities. Then, the SPE diaphragm is damaged to generate a large amount of solid fine particles. In addition, when the operation is performed for a long time, metal impurities elute from the anode.

The cathode is selected from the group consisting of platinum, platinum oxide, tantalum, tantalum oxide and / or iridium oxide on the surface of a porous titanium substrate or a punched titanium substrate by any of a firing method, a plating method and a sputtering method. It is manufactured by coating at least one or more as an active layer.

The power supply body is selected from the group consisting of platinum, platinum oxide, tantalum, tantalum oxide and / or iridium oxide on the surface of the ring-shaped titanium substrate or the punched titanium substrate by any of a firing method, a plating method and a sputtering method. It is produced by coating at least one or more kinds obtained. In the case of a ring shape, it is used by welding to an anode and a cathode.

The tanks of the anode chamber 3 and the cathode chamber 4 are made of Teflon.

The anode chamber 3 and the cathode chamber 4 of the electrolytic cell unit 2
A Teflon valve and a flange for attaching and detaching the electrolytic cell unit are respectively attached to the pipes for the supply water 1 and 1 '. Also, the Teflon valve and the flange are similarly attached to the pipes for the anode chamber discharge water 6 and the cathode chamber discharge water 7, respectively. In the event of an emergency such as electrode replacement in the electrolytic cell unit 2, the valve and flange attached to each pipe can easily shut off the electrolytic cell unit.

The number of the electrolytic cell units 2 is preferably at least three in consideration of stability in long-term continuous operation and workability at the time of electrode replacement.

FIG. 1 shows a two-chamber diaphragm cell unit 2
Any type, depending on the purpose, such as an integrated type in which a plurality of electrolytic cell units 2 are integrated or a one-band type in parallel type in which integrated types are arranged in parallel. Good.

In the apparatus for producing electrolytic water for cleaning according to the present invention, pure water or ultrapure water is supplied to the anode chamber 3 and the cathode chamber 4 of the two-chamber diaphragm electrolyzer unit 2 as the supply water 1 and 1 ′. The body is subjected to a direct current 5 to be electrolyzed, and from the anode chamber 3, there is no metal impurity and substantially no solid fine particles.
The neutral oxidizing anode chamber discharge water 6 is generated from the cathode chamber 4, and the cathode chamber 4 generates neutral and reducing cathode chamber discharge water 7 containing no metal impurities and containing a very small amount of solid fine particles.

The anode chamber discharge water 5 has a higher oxidation-reduction potential (hereinafter abbreviated as "ORP") than the supply water 1, oxidizes and dissolves the metal, and has no etching effect on the substrate surface. The cathode chamber discharge water 7 has an ORP lower than that of the supply water 1 ', has a capability of removing solid fine particles, and has no etching action on the substrate surface.

The anode used in the present invention has a smoothness of 10 to 80.
% Of the expanded titanium substrate is used. Even if the expanded titanium substrate is brought into close contact with the SPE diaphragm, it is not damaged, and the obtained anode chamber discharge water 6 can be removed by contact between the anode and the SPE diaphragm as in the conventional case. There are no solid fine particles generated and no metal impurities.

A gas dissolving filter 9 may be connected to the pipe for the anode chamber discharge water 6 to increase the dissolved gas concentration and further increase the oxidation-reduction potential.

The electrolytic water for anode cleaning 10 is neutral and oxidizing, having no metallic impurities, substantially no solid fine particles, no etching effect on the substrate surface.

On the other hand, although the cathode chamber discharge water 7 has no metal impurities, a very small amount of solid fine particles are generated.
Although this does not cause any particular problem, if this is also a problem, it is used after a very small amount of solid fine particles is removed by connecting a solid fine particle removing filter 8 to the pipe for the cathode chamber discharge water 7.

Examples of the fine particle removal filter 8 include a Teflon hollow fiber filter and a Teflon membrane filter.

Further, a gas dissolving filter 9 'may be connected to the pipe for the discharge water 7 of the cathode chamber to increase the dissolved gas concentration and further reduce the oxidation-reduction potential.

The electrolytic water 11 for cleaning the cathode has no metal impurities, substantially no solid fine particles, has no etching effect on the substrate surface, is neutral and reducible.

The generator of the present invention can be electrolyzed only by supplying pure water or ultrapure water without adding any electrolyte.

The electrolytic water for anode cleaning 10 obtained by the generator of the present invention can be used without etching the substrate surface.
Metal impurities can be removed by oxidative dissolution of the metal. In addition, when used for final cleaning, a uniform, thin and very good oxidation protection film can be formed. On the other hand, the electrolytic water for cathode cleaning 11 can remove solid fine particles without etching the substrate surface.

The apparatus of the present invention can obtain a substrate surface with extremely high cleanliness by washing by combining the obtained electrolytic water for anode cleaning and electrolytic water for cathode cleaning.

The generator of the present invention can be operated stably even during long-term continuous operation, and can be easily replaced without interrupting the operation even during electrode replacement.

[0039]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An example will be described with reference to FIG. Note that the present invention is not limited to the embodiments.

Example An apparatus for producing electrolytic water for cleaning according to the present invention was produced as follows.

Step width 1.0m flat processed to 50% smoothness
An anode in which a mixture of iridium oxide / tantalum oxide = 7/3 is coated on the surface of an expanded titanium substrate by a firing method, a cathode in which platinum oxide is coated on a porous titanium substrate surface by a firing method, and a ring-shaped titanium substrate surface After preparing a power supply body coated with platinum oxide by a firing method,
The anode and the power supply, and the cathode and the power supply were welded, respectively.

SPE diaphragm (registered trademark: Nafion 11)
7, manufactured by Dupont Co., Ltd.), an anode to which a power supply is welded, and a cathode to which a power supply is welded are arranged on both side surfaces thereof, and a Teflon tank body is provided on both outer surfaces thereof. A two-chamber type membrane electrolytic cell unit 2 including an anode chamber 3 and a cathode chamber 4 separated by an SPE membrane was prepared. Each contact portion is sealed with Teflon packing.

Four of the prepared electrolytic cell units 2 are arranged in parallel, and Teflon for attaching / detaching the electrolytic cell unit is installed in the piping for the water 1, 1 ′ supplied to the anode chamber 3 and the cathode chamber 4 of the electrolytic cell unit 2. A valve and a flange were attached. Also, a Teflon valve and a flange were similarly attached to the pipes for the anode chamber discharge water 6 and the cathode chamber discharge water 7, respectively.

Next, a gas dissolving filter 9 made of Teflon was connected to the piping for the anode chamber discharge water 6 of each electrolytic cell unit.

The Teflon fine particle removal filter 8 and the Teflon gas dissolving filter 9 ′ were connected to the cathode chamber discharge water 8 pipe of each electrolytic cell unit 2.

Ultrapure water was supplied at a rate of 2 L / min to each of the anode chamber 3 and the cathode chamber 4 of each electrolytic cell unit 2 as the supply water 1 and 1 ′, and was supplied with a current of 10 A and electrolyzed for 50 hours. Then, neutral oxidizing cleaning water was generated from the anode chamber, and neutral reducing cleaning water was generated from the cathode chamber.

The anode chamber discharge water 6 is supplied to the gas dissolving filter 9
To increase the dissolved gas concentration to obtain electrolytic water for anode cleaning 10 having no metal impurities and substantially no solid fine particles.

ORP meter (HBM-1 manufactured by Electrochemical Instruments Inc.)
02), electrolysis water for anode cleaning after electrolysis for 50 hours
Measured RP, + 80mV compared to ORP of feed water
Met. Table 1 shows the results.

Also, using an inductively coupled plasma gravimetric analyzer (PMS2000 manufactured by Yokogawa Electric Corporation), metal impurities (B (detection limit: 50 ppt)) in the discharge water of the anode chamber and the electrolytic water for anode cleaning after electrolysis for 50 hours, Na (detection limit 1ppt), Mg (detection limit 1ppt), Al (detection limit 1ppt), K (detection limit 10ppt)
t), Ca (detection limit 10ppt), Ti (detection limit 50ppt), Cr
(Detection limit 10ppt), Mn (detection limit 5ppt), Fe (detection limit 5ppt), Ni (detection limit 5ppt), Cu (detection limit 5ppt),
Zn (detection limit 15 ppt), Sn (detection limit 30 ppt), Ba (detection limit 50 ppt), W (detection limit 50 ppt), Ir (detection limit 5 ppt),
When Pt (detection limit: 40 ppt), Ta (detection limit: 50 ppt), and Pb (detection limit: 10 ppt)), all of the water discharged from the anode chamber and the electrolytic water for anode cleaning were below the detection limit. Table 1 shows the results
Shown in

Further, a particle counter (Rion
Using KL-26 (manufactured by Co., Ltd.), solid fine particles (particle diameter: 0.2 μm) in the anode chamber discharge water after the electrolysis for 50 hours and the electrolytic water for anode cleaning.
As a result, the water discharged from the anode chamber and the electrolytic water for cleaning the anode were 1 / ml.

The cathode chamber discharge water 7 is removed by a fine particle removing filter 8 to remove solid fine particles in the liquid, and then the dissolved gas concentration is increased through a gas dissolving filter 9 ′. No electrolytic water 11 for cathode cleaning was obtained.

The metal impurities and solid fine particles discharged from the cathode chamber after the electrolysis for 50 hours were all below the detection limit, that is, 10 particles / ml, and the ORP, metal impurities and solid fine particles of the electrolytic water for cathode cleaning were -620 mV. All were below the detection limit: 0 / ml.

After the continuous electrolysis for 2,000 hours, the metal impurities and solid fine particles discharged from the anode chamber were all below the detection limit.
1 ml, and ORP, electrolyzed water for anode cleaning, metal impurities and solid fine particles were +80 mV, all below the detection limit.
Pieces / ml.

The metal impurities and solid fine particles in the cathode chamber discharge water after continuous electrolysis for 2,000 hours were all below the detection limit, and 12
The ORP, electrolysis water for cathode cleaning, metal impurities and solid fine particles were -630 mV, all of which were below the detection limit.
Pieces / ml.

[0055]

The production apparatus of the present invention can perform electrolysis only by supplying pure water or ultrapure water without adding any electrolyte.

According to the generator of the present invention, the anode chamber
Neutral oxidizing cleaning water free of metal impurities and substantially free of solid fine particles, and neutral reducing cleaning water free of metal impurities and substantially free of solid fine particles are simultaneously obtained from the cathode chamber.

The electrolytic water for anode cleaning obtained by the production apparatus of the present invention can remove metal impurities by oxidative dissolution of metal without etching action on the substrate surface. A very good and uniform oxide protective film can be formed. Further, the electrolytic water for cleaning the cathode can remove solid fine particles without etching the substrate surface.

By cleaning the substrate surface by combining the electrolyzed water for anode cleaning and the electrolyzed water for cathode cleaning obtained by the production apparatus of the present invention, it is possible to obtain a highly clean substrate surface.

The generator of the present invention can be operated stably even during long-term continuous operation, and can be easily replaced even when replacing electrodes without interrupting the operation.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an apparatus for producing electrolytic water for cleaning according to the present invention, in which four electrolytic cell units are arranged in parallel.

[Explanation of symbols]

 1, 1 'supply water 2 electrolytic cell unit 3 anode compartment 4 cathode compartment 5 DC power supply 6 anode compartment discharge water 7 cathode compartment discharge water 8 particulate removal filter 9, 9' gas dissolution filter 10 anode cleaning electrolysis water 11 cathode cleaning Electrolyzed water

Claims (6)

[Claims] 1. An anode chamber in which an active layer is coated on the surface of an expanded titanium substrate flat-processed to have a smoothness of 10 to 80%, an anode chamber containing an anode feeder, a solid polymer electrolyte membrane, a cathode and a cathode feeder. In the apparatus for generating electrolytic water for cleaning, comprising a two-chamber diaphragm electrolyzer unit comprising a housed cathode chamber, and a pipe for supply water and a pipe for discharge water are arranged,
An apparatus for generating electrolyzed water for cleaning, comprising a plurality of the electrolyzer units. 2. The apparatus for producing electrolytic water for cleaning according to claim 1, wherein the number of electrolytic cell units is at least three or more. 3. The apparatus for producing electrolytic water for cleaning according to claim 1, wherein a valve and a flange are respectively provided on supply water and discharge water pipes of the electrolytic cell unit. 4. The apparatus for producing electrolytic water for cleaning according to claim 1, wherein the water discharged from the anode chamber is passed through a gas dissolving filter. 5. The cathode chamber discharge water is passed through a filter for removing solid fine particles.
The apparatus for generating electrolytic water for cleaning according to any one of the above. 6. The apparatus for producing electrolytic water for cleaning according to claim 1, wherein the water discharged from the cathode chamber is passed through a gas dissolving filter.