JPH11244677A - Apparatus for producing gas-dissolved water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce hydrogen-dissolved water having a specified dissolved hydrogen concn. without the fluctuation in the dissolved hydrogen concn. in spite of a fluctuation in the supply flow rate of ultra-pure water with an apparatus for producing the hydrogen-dissolved water by dissolving gaseous hydrogen into the ultra-pure water. SOLUTION: A pressure controller 19 is mounted at a gas supply passage 16 of a gas dissolution device 2 and a current controller 21 is electrically connected to the pressure controller 19. The gaseous hydrogen generated by electrolysis of water is supplied to the gas supply passage 16 of the device 2 and the ultra-pure water is supplied to a water supply passage 17 of the device 2. When the supply flow rate of the ultra-pure water fluctuates, the electrolytic current value is changed by the action of the pressure controller 19 and the current controller 21, by which the generating amt. of the gaseous hydrogen is regulated and the gaseous hydrogen pressure in the gas supply passage 16 is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-dissolved water producing apparatus for producing gas-dissolved water by dissolving a fixed amount of gas such as hydrogen-dissolved water used as cleaning water in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, cleaning is performed to remove fine particles, organic substances, metals, natural oxide films and the like adhering to the surface of a silicon wafer. A cleaning solution such as a mixed solution of a hydrogen oxide solution and a hydrofluoric acid solution and ultrapure water for rinsing are used. However, rinsing with ultrapure water is not without any problem, and there is a problem that dissolved oxygen in ultrapure water forms a thin oxide film on the silicon wafer surface. Several methods for cleaning such as rinsing using hydrogen-dissolved water obtained by dissolving hydrogen gas in water have already been proposed.

As a method of dissolving hydrogen gas in ultrapure water, a method of supplying hydrogen gas from a gas cylinder to dissolve hydrogen gas in ultrapure water or a method of supplying hydrogen gas generated by electrolysis of water to ultrapure water There is a method of dissolving hydrogen gas in water.

As shown in FIG. 2, a method of supplying hydrogen gas from a gas cylinder is a gas cylinder 30 filled with hydrogen gas.
The hydrogen gas is supplied into the gas dissolving device 32 through the gas supply pipe 31. The gas dissolving device 32 is divided into a gas supply passage 34 and a water supply passage 35 via a gas permeable membrane 33, and hydrogen gas is supplied into the gas supply passage 34. On the other hand, the ultrapure water is supplied through the water supply pipe 36 into the water supply passage 35 of the gas dissolving device 32. The hydrogen gas is maintained at a constant gas pressure by the regulator 37 and passes through the gas permeable membrane 33 to the water supply passage 35.
Get into the side and dissolve in ultrapure water.

Thus, ultrapure water in which hydrogen gas is dissolved, that is,
The hydrogen-dissolved water flows out of the gas dissolving device 32, and the water outflow pipe 3
For example, it is sent to a cleaning process in a semiconductor manufacturing factory through 8.

In the case of the above method, a plurality of gas cylinders including a spare must be prepared at all times.
Gas cylinders had to be replaced regularly, which was inconvenient to handle. In addition, since the piping for the hydrogen gas is extended for a long time, equipment costs are increased, and there is a risk of hydrogen gas leaking and a reduction in hydrogen gas purity.

As shown in FIG. 3, a method of supplying hydrogen gas generated by the electrolysis of water is as follows. The hydrogen gas generated in the electrolytic device 39 is supplied to a gas-liquid separator 40 and a gas supply pipe 41.
The gas is supplied to the gas supply passage 43 of the gas dissolving device 42 through the passage. In this case, an excessive amount of hydrogen gas is supplied to the gas supply passage 43, the hydrogen gas is dissolved in the ultrapure water through the gas permeable membrane 44, and the excess hydrogen gas that has not been completely dissolved in the ultrapure water is supplied to the gas outlet pipe. It flows out of the fuel cell 45 and is led to the hydrogen gas combustion device 46. Here, the hydrogen gas is heated in an atmosphere of air or oxygen supply, and at the same time, is brought into contact with a hydrogen combustion catalyst such as palladium, so that the surplus hydrogen gas is burned to make it safe and harmless. 47 is a pressure control valve for adjusting the amount of excess hydrogen gas, and 48 is a water supply pipe.

[0008] Thus, hydrogen-dissolved water is obtained, and this hydrogen-dissolved water flows out of the water outflow pipe 49.

[0009]

According to the method using the electrolytic device 39, the trouble of preparing and replacing the gas cylinder is not required, but the supply flow rate of the ultrapure water to the gas dissolving device 42 varies. Then, the hydrogen gas pressure in the device 42 also fluctuates, and as a result, there is a disadvantage that the concentration of dissolved hydrogen in ultrapure water cannot be kept constant. For example, when the supply flow rate of ultrapure water increases, the amount of dissolved hydrogen gas increases, and the hydrogen gas pressure in the gas dissolving device 42 decreases accordingly. By reducing the hydrogen gas pressure, the amount of hydrogen gas dissolved in ultrapure water is reduced, and as a result, the dissolved hydrogen concentration of the obtained hydrogen-dissolved water becomes lower than a predetermined concentration. in this way,
The above method has a problem that the concentration of dissolved hydrogen in the hydrogen-dissolved water cannot be kept constant when the supply flow rate of the ultrapure water changes.

In addition, the above-mentioned method generates excess hydrogen gas, so that it requires extra electrolysis power, not only consumes excessive energy, but also requires a combustion facility for burning the excess hydrogen gas. Were soaring and economically disadvantaged.

[0011] The present invention has been made in view of the above points,
It is an object of the present invention to provide a gas-dissolved water producing apparatus that can always produce gas-dissolved water having a constant dissolved hydrogen concentration even when the supply flow rate of pure water fluctuates.

Another object of the present invention is to provide an economically advantageous gas-dissolved water producing apparatus capable of reducing production costs without wasting energy consumption.

[0013]

SUMMARY OF THE INVENTION The present invention relates to (1) an electrolytic device for electrolyzing water, a gas dissolving device for dissolving gas generated by the electrolysis of water in pure water, and a gas dissolving device. A gas pressure adjusting means for detecting the gas pressure in the gas, controlling the electrolysis current value of the electrolysis device, and adjusting the gas pressure to a constant gas pressure.
(2) The gas pressure adjusting means includes a pressure controller attached to the gas dissolving device, and a current controller electrically connected to the pressure controller and adjusting an electrolytic current value of the electrolytic device. (1) The gas-dissolved water producing apparatus according to (1),
(3) The gas dissolving device is provided with a gas supply passage and a water supply passage through a gas permeable membrane.
(4) The gas-dissolved water producing apparatus according to (1), wherein the gas is hydrogen gas.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of a gas-dissolved water producing apparatus according to the present invention. In the figure, 1 is an electrolysis device, 2
Denotes a gas dissolving device, and the electrolytic device 1 has an anode chamber 4 and a cathode chamber 5 partitioned by an ion exchange membrane 3. 6 is an anode and 7 is a cathode. The electrolysis apparatus 1 has an inflow pipe 8 for supplying pure water, an outflow pipe 9 for flowing out hydrogen gas generated by water electrolysis, and an outflow pipe 10 for flowing out oxygen gas similarly generated by water electrolysis. The outlet pipe 9 is connected to a gas-liquid separator 11, and a gas supply pipe 12 is provided between the gas-liquid separator 11 and the gas dissolving device 2.
13 is a level switch attached to the gas-liquid separator 11, and 14 is a valve.

The gas dissolving device 2 has a gas supply passage 16 and a water supply passage 17 partitioned by a gas permeable membrane 15.
The gas supply pipe 16 is connected to the gas supply pipe 16,
A water supply pipe 18 is connected to the water supply passage 17. The inflow pipe 8 provided in the electrolysis apparatus 1 is provided in a state of branching from the water supply pipe 18. A pressure controller 19 is mounted on the gas supply passage 16 side of the gas melting device 2. The mounting position of the pressure controller 19 is the gas supply passage 1
6 or the inside of the passage 16, and its mounting position is arbitrary. The pressure controller 19 is a gas dissolving device 2
The gas supply pipe 12 may be attached to any position, for example.

A current controller 21 is electrically connected between the electrolyzer 1 and the DC power supply 20, and the pressure controller 19 is electrically connected to the current controller 21. Reference numeral 22 denotes a water outflow pipe for flowing out the hydrogen-dissolved water obtained by the gas dissolving device 2.

As the gas permeable film 15 in the gas dissolving apparatus 2, a film made of a gas-philic material such as silicon or a film made of a water-repellent material such as a fluorine resin is provided with a large number of fine holes through which gas can pass. For example, one configured to transmit gas but not water can be used. Gas permeable membrane 15
For example, when the gas permeable membrane 15 is formed in a hollow fiber structure, a method of dissolving gas from the inner space side of the hollow fiber to the outside is used as a gas dissolving method. Any of the methods of allowing gas to permeate into the inner space side can be adopted.

Although the present invention dissolves hydrogen gas in pure water, it is particularly preferable to use ultrapure water among the pure water in applying the present invention.

In the present invention, ultrapure water is industrial water,
Raw water such as tap water, well water, river water, lake water, etc. is treated with a pre-treatment device such as coagulation sedimentation, filtration, coagulation filtration, activated carbon treatment, etc. to remove coarse suspended substances and organic matter in the raw water. Then, by processing in a primary pure water producing apparatus mainly comprising a desalination apparatus such as an ion exchange apparatus and a reverse osmosis membrane apparatus,
Removal of most of impurities such as fine particles, colloidal substances, organic substances, metal ions and anions, and treatment of this primary pure water with an ultraviolet irradiation device, mixed-bed polisher, ultrafiltration membrane and reverse osmosis membrane It refers to high-purity pure water in which impurities such as fine particles, colloidal substances, organic substances, metal ions, and anions have been removed as much as possible by circulating in a secondary pure water production system. Is, for example, an electric resistivity of 17.0 MΩ · cm or more, a total organic carbon of 100 μgC / liter or less, and a number of fine particles (particle size 0.07
μm or less), the number of viable bacteria is 50 or less, silica is 10 μg SiO ₂ /
Liter or less, sodium 0.1 μg Na / liter or less.

The operation of the apparatus of the present invention configured as described above will be described below. In the following description, a case where ultrapure water is used as pure water will be described.

Ultrapure water is supplied from a water supply pipe 18, and the ultrapure water flows into the electrolysis apparatus 1 via the inflow pipe 8, where the water is electrolyzed. Hydrogen gas is generated on the cathode 7 side by the electrolysis of water. What flows out of the cathode chamber 5 is a gas-liquid mixture of hydrogen gas and water, and this gas-liquid mixture flows into the gas-liquid separator 11 through the outflow pipe 9.

In the gas-liquid separator 11, hydrogen gas and water are separated, and the hydrogen gas is led to the gas dissolving device 2 through the gas supply pipe 12. On the other hand, the water stays in the gas-liquid separator 11, and when the water level exceeds a predetermined position, the level switch 13 is operated and the valve 1 is activated by an electric signal.
4 is opened, a predetermined amount of water in the gas-liquid separator 11 is discharged, and control is performed so that the level of the retained water becomes constant.

In the electrolysis apparatus 1, oxygen gas is generated on the anode 6 side, and this oxygen gas flows from the anode chamber 4 to the outlet pipe 10.
Is discharged out of the system. Incidentally, residual water in the electrolysis apparatus 1 is also discharged through the outflow pipe 10.

As described above, the hydrogen gas introduced from the gas supply pipe 12 to the gas dissolving device 2 is supplied to the gas supply passage 1 of the device 2.
Flow into 6. On the other hand, ultrapure water is supplied to a water supply passage 17 of the device 2 from a water supply pipe 18. The hydrogen gas passes through the gas permeable membrane 15 and enters the water supply passage 17, where it is dissolved in ultrapure water to obtain hydrogen-dissolved water.

Here, the pressure controller 19 is provided in the gas dissolving apparatus 2 (more specifically, in the gas supply passage 16 of the apparatus).
The hydrogen gas pressure is adjusted in advance so as to be constant. Therefore, when water and hydrogen gas come into contact with each other in the water supply passage 17, an amount of dissolved hydrogen gas is obtained based on the set pressure, and hydrogen-dissolved water having a predetermined dissolved hydrogen concentration is produced. The hydrogen-dissolved water flows out of the system through the water outflow pipe 22, is sent to a cleaning process in a semiconductor manufacturing plant, for example, and is used as cleaning water for a semiconductor substrate such as a silicon wafer.

The hydrogen gas pressure set by the pressure controller 19 is preferably 0 to 5 kgf / cm ² G. 0kgf
If the concentration is less than / cm ² G, the dissolved amount of hydrogen gas in water is small, and hydrogen-dissolved water having a target dissolved hydrogen concentration cannot be obtained. When the pressure exceeds 5 kgf / cm ² G, the water supply passage 17
Gas bubbles of hydrogen gas are generated in the gas, and the bubbles are present in the hydrogen-dissolved water, so that a predetermined dissolved hydrogen concentration cannot be obtained, and this is not preferable in terms of handling.

When the supply flow rate of the ultrapure water sent to the gas dissolving apparatus 2 through the water supply pipe 18 fluctuates, the amount of dissolved hydrogen gas fluctuates, and as a result, the hydrogen gas pressure in the gas supply passage 16 also increases. Although the pressure fluctuates, the pressure controller 19 promptly returns to the predetermined set pressure.

For example, when the supply flow rate of ultrapure water increases, the amount of dissolved hydrogen gas also increases.
The hydrogen gas pressure in 6 decreases. When the hydrogen gas pressure becomes lower than a set pressure (for example, 0 to 5 kgf / cm ² G), the sensor of the pressure controller 19 detects the pressure drop and outputs an electric signal to electrically control the current control device 21. To make the electrolytic current value larger. When the electrolysis current value increases due to such current control, the amount of hydrogen gas generated by the electrolysis of water increases, and the gas pressure of the hydrogen gas supplied to the gas supply passage 16 of the gas dissolving apparatus 2 increases. To the set pressure. Therefore, a predetermined amount of dissolved hydrogen gas is obtained based on the set pressure.

As described above, according to the present invention, the hydrogen gas pressure in the gas supply passage 16 is controlled to a constant pressure. Therefore, even if the supply flow rate of the ultrapure water increases as described above, it corresponds to the hydrogen gas pressure. A predetermined amount of dissolved hydrogen gas is obtained, and hydrogen dissolved water having a constant dissolved hydrogen concentration is obtained. When the supply flow rate of the ultrapure water increases, the hydrogen dissolved water having a dissolved hydrogen concentration lower than the predetermined concentration is obtained. The disadvantage of the prior art that can only be obtained can be surely solved.

On the contrary, when the supply flow rate of the ultrapure water decreases, the amount of dissolved hydrogen gas decreases, and the hydrogen gas pressure in the gas supply passage 16 becomes higher than the set pressure.
In this case, the sensor of the pressure controller 19 detects the pressure increase and outputs an electric signal, and the current control device 21 inputs the electric signal and performs current control so as to reduce the electrolytic current value.

As a result of the current control, the amount of hydrogen gas generated by the electrolysis of water is reduced, the hydrogen gas pressure in the gas supply passage 16 is reduced, and the pressure is quickly returned to the set pressure. Hydrogen dissolved water having a dissolved hydrogen concentration is obtained.

In the above-described embodiment of the present invention, the case where hydrogen gas is dissolved in ultrapure water has been described, but the present invention is not limited to this. That is, as another embodiment of the present invention, the oxygen gas produced by the electrolysis device 1 is supplied to the gas dissolving device 2 and this oxygen gas can be dissolved in ultrapure water to produce oxygen dissolved water. In this case, as described in the above embodiment, the oxygen gas pressure is always controlled to be constant by the pressure controller 19, and the oxygen-dissolved water having a constant dissolved oxygen concentration is always maintained even when the supply flow rate of the ultrapure water varies. Can be obtained. This oxygen-dissolved water can also be used as cleaning water for a cleaning step in a semiconductor manufacturing plant.

[0034]

The present invention relates to a gas dissolving apparatus configured to dissolve a gas generated by electrolysis of water into pure water by a gas dissolving apparatus. Since the gas pressure adjusting means for controlling the electrolytic current value of the gas and adjusting the gas pressure to a constant gas pressure is provided, the gas pressure in the gas dissolving apparatus is adjusted to be constant even when the supply flow rate of pure water fluctuates. As a result, a predetermined gas dissolution amount based on a constant gas pressure can be obtained irrespective of fluctuations in the pure water supply flow rate. Therefore, according to the present invention, there is an effect that the dissolved gas concentration of the gas-dissolved water can always be kept constant even if the pure water supply flow rate fluctuates.

Further, according to the present invention, since gas is generated and gas is dissolved in accordance with the set pressure, unnecessary electrolytic power is not consumed, so that the production cost can be reduced and the cost is economically advantageous. There is an effect that becomes something.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an apparatus for producing gas-dissolved water of the present invention.

FIG. 2 is a schematic view showing a conventional apparatus for producing gas-dissolved water.

FIG. 3 is a schematic view showing a conventional gas-dissolved water producing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolysis apparatus 2 Gas dissolution apparatus 19 Pressure controller 21 Current control apparatus

Claims (4)

[Claims] An electrolysis apparatus for electrolyzing water, a gas dissolving apparatus for dissolving a gas generated by the electrolysis of water in pure water, and a gas pressure in the gas dissolving apparatus for detecting the gas pressure in the gas dissolving apparatus. A gas pressure adjusting means for controlling an electrolytic current value of the gas to adjust the gas pressure to a constant gas pressure. 2. A gas pressure adjusting means comprising: a pressure controller attached to a gas dissolving device; and a current controller electrically connected to the pressure controller and adjusting an electrolytic current value of the electrolytic device. The apparatus for producing gas-dissolved water according to claim 1. 3. The gas-dissolved water producing apparatus according to claim 1, wherein the gas-dissolving apparatus is provided with a gas supply passage and a water supply passage via a gas permeable membrane. 4. The apparatus according to claim 1, wherein the gas is hydrogen gas.