JP3768027B2 - Gas dissolved water production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas-dissolved water production apparatus for producing gas-dissolved water obtained by dissolving a certain amount of gas such as hydrogen-dissolved water used as cleaning water in a semiconductor production process, for example.
[0002]
[Prior art]
In the semiconductor manufacturing process, cleaning is performed to remove fine particles, organic substances, metals, natural oxide films, etc. adhering to the silicon wafer surface. In this cleaning process, a mixed solution of sulfuric acid and hydrogen peroxide solution is used. A cleaning solution such as a hydrofluoric acid solution is used, and ultrapure water is used as rinsing water for rinsing after cleaning. However, rinsing with ultrapure water is not a problem at all, and there is a problem that a thin oxide film is formed on the surface of the silicon wafer due to dissolved oxygen in ultrapure water. Several methods have already been proposed for cleaning such as rinsing using hydrogen-dissolved water in which hydrogen gas is dissolved.
[0003]
In producing hydrogen-dissolved water, there is a method of dissolving hydrogen gas in ultrapure water by supplying hydrogen gas generated by electrolysis of water as a method of dissolving hydrogen gas in ultrapure water.
[0004]
As shown in FIG. 3, this hydrogen gas melting method supplies hydrogen gas generated in the electrolysis apparatus 1 to a gas supply passage 5 of the gas dissolution apparatus 4 through a gas-liquid separator 2 and a gas supply pipe 3. In the figure, 6 is a DC power source for the electrolysis apparatus. Here, the ultrapure water is guided to the water supply passage 8 of the gas dissolving device 4 through the water supply pipe 7, and in this gas dissolving device 4, the hydrogen gas passes through the gas permeable membrane 9 and is dissolved in the ultrapure water, Hydrogen-dissolved water is obtained.
[0005]
The hydrogen-dissolved water thus obtained is sent to a cleaning process in a semiconductor manufacturing factory, for example, through the water outflow pipe 10.
[0006]
The hydrogen gas generated by the electrolysis of water contains water vapor in a saturated state. Therefore, condensation of water vapor occurs in the gas supply passage 5 of the gas dissolving device 4, and condensed water is gradually produced in the passage 5. The situation of staying occurs. Further, water vapor in the water supply passage 8 is reversely diffused to the gas supply passage 5 side through the gas permeable membrane 9, and the reverse diffused water vapor is condensed in the gas supply passage 5, and the condensed water generated thereby is condensed in the passage 5. Occasionally, the situation of stagnation gradually appears.
[0007]
Condensed water gradually accumulates in the gas supply passage 5 due to the two factors described above, and the boundary area where hydrogen gas contacts ultrapure water through the gas permeable membrane in the gas dissolving device due to the retention of this condensed water. It narrows, and the malfunction that gas dissolution efficiency will fall arises.
[0008]
Therefore, conventionally, a drain tank 11 is installed below the gas dissolving device 4, and condensed water generated in the gas supply passage 5 is sent to the drain tank 11, and measures are taken so that the condensed water does not stay in the passage 5. .
[0009]
[Problems to be solved by the invention]
In the structure provided with the drain tank 11, condensed water is stored in the drain tank 11, and when the water level reaches the upper limit water level, the level sensor 12 operates to open the valve 13, discharge condensed water, and accompany drainage. When the water level of the condensed water in the tank reaches the lower limit water level, the other level sensor 14 is activated to close the valve 13.
[0010]
In this way, the two sensors are provided to monitor the level of the condensed water in the tank. When the drainage system including the drain tank 11 is opened, the hydrogen gas in the gas supply passage 5 passes through the drainage system. This is because the hydrogen gas pressure in the passage 5 drops and the valve opening / closing control needs to be performed.
[0011]
As described above, in order to prevent the condensate from staying in the gas dissolving device, a new device called a drain tank is provided, and a level sensor for controlling the amount of stored water in the drain tank is provided. As a result, the structure of the gas-dissolved water production apparatus as a whole becomes complicated, resulting in an increase in manufacturing costs and an increase in the probability of failure due to the addition of a new control system. As a result, there is a disadvantage that it is disadvantageous in terms of maintenance.
[0012]
The present invention has been made in view of the above points, and an object of the present invention is to provide a gas-dissolved water manufacturing apparatus that has a simple structure, can reduce manufacturing costs, and can solve the problem of failure.
[0013]
[Means for Solving the Problems]
The present invention relates to (1) a gas supply passage of a gas dissolving apparatus in a gas dissolving water producing apparatus having a gas dissolving apparatus for dissolving a gas generated by electrolysis of water into pure water through a gas permeable membrane. The condensed water drain pipe is provided, and the condensed water drain pipe is connected to the gas-liquid separator so that the condensed water generated in the gas supply passage of the gas dissolving apparatus is discharged to the gas-liquid separator. A gas-dissolved water production apparatus characterized by that. (2) The gas-liquid separator includes a level sensor, and is configured such that water exists in the gas-liquid separator between the upper limit water level and the lower limit water level. 1) The gas-dissolved water production apparatus according to 1).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 shows an embodiment of the gas-dissolved water production apparatus of the present invention. In the figure, 20 is an electrolysis apparatus, 21 is a gas dissolution apparatus, 22 is a gas-liquid separator, and the electrolysis apparatus 20 has an anode chamber 24 and a cathode chamber 25 partitioned by an ion exchange membrane 23. Reference numeral 26 denotes an anode, 27 denotes a cathode, and 28 denotes a DC power source for the electrolysis apparatus. Two water inflow pipes 30 and 31 are branched from a water supply pipe 29 for supplying pure water. One water inflow pipe 30 is connected to the electrolysis apparatus 20, and the other water inflow pipe 31 is connected to the gas dissolving apparatus 21. . The electrolysis apparatus 20 is provided with a hydrogen gas outflow pipe 32 for flowing out hydrogen gas generated by water electrolysis and an oxygen gas outflow pipe 33 for flowing out oxygen gas generated by water electrolysis. The gas outflow pipe 32 is connected to the gas-liquid separator 22, and a gas supply pipe 34 is connected between the gas-liquid separator 22 and the gas dissolving device 21. A drain pipe 35 is attached to the gas-liquid separator 22.
[0016]
The gas-liquid separator 22 is a device having a gas-liquid separation mechanism, and is provided with a space 36 for separating hydrogen gas and water. The gas-liquid separator 22 is provided with a level sensor 37 for detecting the upper limit water level of the stored water and a level sensor 38 for detecting the lower limit water level of the stored water, and is electrically connected to these sensors 37, 38. A valve 39 whose opening and closing is controlled is provided in the drain pipe 35.
[0017]
The gas dissolving device 21 has a gas supply passage 41 and a water supply passage 42 partitioned through a gas permeable membrane 40, the gas supply passage 41 is connected to the gas supply pipe 34, and the water supply passage 42 is connected to the gas supply passage 42. A water inflow pipe 31 is connected. Further, a water outflow pipe 43 is connected to the outlet side of the water supply passage 42.
[0018]
Further, a condensed water drain pipe 44 is provided below the gas supply passage 41 in the gas dissolving device 21, and the condensed water drain pipe 44 is connected to the gas-liquid separator 22. The condensed water drain pipe 44 is a liquid feed pipe for discharging condensed water generated in the gas supply passage 41 into the gas-liquid separator 22. In the present invention, the drainage mechanism is natural drainage or forced drainage by a pump. But you can. In the case of natural flow drainage, the gas-liquid separator 22 is set so that the attachment position A of the condensed water drain pipe 44 in the gas supply passage 41 is higher than the upper limit water level B of the stored water in the gas-liquid separator 22. It is necessary to provide at a position below the gas dissolving device 21. On the other hand, in the case of forced drainage by a pump, there is no restriction on the setting position of the drainage pipe 44 described above, and the vertical positional relationship between the gas dissolving device 21 and the gas-liquid separator 22 can be arbitrarily set.
[0019]
The gas permeable film 40 in the gas dissolving apparatus 21 is provided with a large number of fine holes through which gas can permeate through a film made of a hydrophilic material such as silicon or a film made of a water repellent material such as fluorine-based resin. However, those configured so that water does not permeate are used. The gas permeable membrane 40 can be configured, for example, as a hollow fiber-like structure, and when the gas permeable membrane 40 is formed in a hollow fiber-like structure, a method of allowing gas to permeate from the inner space side of the hollow fiber to the outside as a gas dissolution method Any method of allowing gas to permeate from the outside of the hollow fiber to the inner space side can be employed.
[0020]
In the present invention, hydrogen gas (oxygen gas in other embodiments) is dissolved in pure water. In this case, it is particularly preferable to use ultrapure water in pure water.
[0021]
In the present invention, ultrapure water means raw water such as industrial water, clean water, well water, river water, lake water, etc., by treating it with a pretreatment device such as coagulation sedimentation, filtration, coagulation filtration, activated carbon treatment, etc. By removing coarse suspended substances, organic substances, etc. in the water, and then treating with primary deionized water production equipment mainly composed of desalination equipment such as ion exchange equipment, reverse osmosis membrane equipment, fine particles, colloidal materials, organic matter, The secondary pure water consists of a membrane treatment device that removes most of the impurities such as metal ions and anions, and further equips this primary pure water with an ultraviolet irradiation device, mixed bed polisher, ultrafiltration membrane and reverse osmosis membrane. High-purity pure water from which impurities such as residual fine particles, colloidal substances, organic substances, metal ions, and anions are removed as much as possible by circulating treatment in a production apparatus.
[0022]
The operation of the device 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.
[0023]
Ultrapure water is supplied from the water supply pipe 29, and the ultrapure water is caused to flow into the electrolysis apparatus 20 through the water inflow pipe 30, where water is electrolyzed. Hydrogen gas is generated on the cathode 27 side by electrolysis of water. Outflowing from the cathode chamber 25 is a gas-liquid mixture of hydrogen gas and water, and this gas-liquid mixture flows into the gas-liquid separator 22 through the hydrogen gas outflow pipe 32.
[0024]
In the gas-liquid separator 22, hydrogen gas and water are separated, and the hydrogen gas is guided to the gas dissolving device 21 through the gas supply pipe 34. On the other hand, water stays in the gas-liquid separator 22.
[0025]
In the electrolysis apparatus 20, oxygen gas is generated on the anode 26 side, and this oxygen gas is discharged from the anode chamber 24 through the oxygen gas outflow pipe 33 to the outside of the system. The surplus water remaining in the electrolyzer 20 is also discharged through the outflow pipe 33.
[0026]
As described above, the hydrogen gas introduced into the gas dissolving device 21 from the gas supply pipe 34 flows into the gas supply passage 41 of the device 21. On the other hand, ultrapure water is supplied to the water supply passage 42 of the apparatus 21 through the water supply pipe 29 and the water inflow pipe 31. The hydrogen gas in the gas supply passage 41 passes through the gas permeable membrane 40 and enters the water supply passage 42, where it is dissolved in ultrapure water to obtain hydrogen-dissolved water.
[0027]
Here, the hydrogen gas supplied from the gas supply pipe 34 contains water vapor in a saturated state, and water vapor condenses in the gas supply passage 41 of the gas dissolving apparatus, resulting in condensed water. Also, ultrapure water is always supplied from the water inflow pipe 31 into the water supply passage 42 of the apparatus, and saturated water vapor exists in the water supply passage 42, and this water vapor passes through the gas permeable membrane 40. Then, it diffuses back into the gas supply passage 41 side. Then, the water vapor that has entered the gas supply passage 41 due to the reverse diffusion is condensed in the passage 41 to generate condensed water.
[0028]
In this way, condensed water is generated in the gas supply passage 41, and this condensed water flows into the gas-liquid separator 22 through the condensed water drain pipe 44 connected to the lower side of the passage 41. The condensed water is immediately discharged to the condensed water drain pipe 44, and therefore the condensed water does not stay in the gas supply passage 41. Although water accompanying the hydrogen gas flowing out from the electrolysis device 20 is retained in the gas-liquid separator 22, the condensed water flows in a form added to the retained water in the gas-liquid separator 22.
[0029]
As described above, the water accompanying the hydrogen gas flowing out from the electrolysis device 20 and the condensed water flowing in from the condensed water drain pipe 44 are gradually stored in the gas-liquid separator 22. When the water level rises and reaches the upper limit water level, the level sensor 37 operates to output an electrical signal, and the valve 39 is opened, whereby the stored water in the gas-liquid separator 22 is discharged out of the system through the drain pipe 35. Is done.
[0030]
The level of the stored water drops with the discharge of the stored water, and when the water level reaches the lower limit water level, the level sensor 38 is activated, an electric signal is output, the valve 39 is closed, and the discharge of the stored water is thereby stopped. . Therefore, a certain amount of water always exists in the gas-liquid separator 22. By performing valve opening / closing control based on the amount of stored water in this way, hydrogen gas in the gas supply passage 41 does not escape out of the system through the condensed water drain pipe 44, the gas-liquid separator 22, and the drain pipe 35, thereby A decrease in the hydrogen gas pressure in the gas supply passage 41 can be prevented.
[0031]
The gas-liquid separator 22 communicates with the cathode chamber 25 of the electrolysis apparatus through the hydrogen gas outflow pipe 32, and therefore, a part of the stored water in the gas-liquid separator 22 passes through the hydrogen gas outflow pipe 32 to the cathode chamber 25. It flows into the water and becomes part of the raw water used for electrolysis of water. Therefore, according to the present invention, the condensed water can be used as a part of the raw material water.
[0032]
The hydrogen-dissolved water produced by the gas dissolving apparatus 21 as described above flows out of the system through the water outflow pipe 43 of the apparatus, and is sent to a cleaning process in a semiconductor manufacturing factory, for example, for cleaning water for a semiconductor substrate such as a silicon wafer. Used as
[0033]
FIG. 2 shows another embodiment of the present invention, which has a configuration in which the use of a gas-liquid separator is omitted by using an electrolysis apparatus having a gas-liquid separation mechanism. In the figure, 45 is an electrolysis apparatus having a gas-liquid separation mechanism, and this electrolysis apparatus 45 is provided with a space for separating the gas generated in the electrode chamber and the water in the electrode chamber. That is, a space 47 for separating hydrogen gas generated in the cathode chamber 46 and water in the cathode chamber 46 is provided above the cathode chamber 46, and oxygen generated in the anode chamber 48 is above the anode chamber 48. A space 49 is provided for decomposing the gas and the water in the anode chamber. 50 is an anode, 51 is a cathode, 52 is an ion exchange membrane, and 53 is a DC power source.
[0034]
The electrolyzer 45 is provided with a level sensor 54 for detecting the upper limit water level and a level sensor 55 for detecting the lower limit water level, and electrically opens and closes a valve 57 attached to the drain pipe 56 of the electrolyzer 45. It is like that. 58 is an oxygen gas outflow pipe, 59 is a gas supply pipe for supplying hydrogen gas generated in the electrolyzer 45 to the gas dissolving apparatus 60, and 61 and 62 are a gas supply passage and a water supply path of the gas dissolving apparatus, respectively. .
[0035]
A condensed water drain pipe 63 is provided below the gas supply passage 61 of the gas dissolving apparatus, and the drain pipe 63 is connected to the cathode chamber 46 of the electrolysis apparatus. Reference numeral 64 is a water supply pipe, 65 and 66 are water inflow pipes, and 67 is a water outflow pipe.
[0036]
In this embodiment, since the electrolyzer 45 itself also functions as a gas-liquid separator, it is not necessary to provide a gas-liquid separator between the electrolyzer 45 and the gas dissolving device 60, and the structure is further simplified. The condensed water generated in the gas supply passage 61 is discharged into the cathode chamber 46 of the electrolysis apparatus through the condensed water drain pipe 63.
[0037]
As a result, the amount of water in the cathode chamber 46 gradually increases, and it is necessary to control the water level with a level sensor. When the water level in the cathode chamber 46 reaches the upper limit water level, the level sensor 54 operates, and the valve 57 is opened to drain from the drain pipe 56, and when the water level reaches the lower limit water level, the level sensor 55 operates to close the valve 57. Stop draining.
[0038]
In each of the embodiments of the present invention described above, a water supply pipe for supplying raw water to the electrolysis apparatus and a water supply pipe for supplying ultrapure water to the gas dissolution apparatus may be provided separately. The ultrapure water that has been subjected to pH adjustment in advance by adding an acid or an alkali as necessary may be supplied to the ultrapure water supplied to.
[0039]
Furthermore, the present invention is not limited to the case of producing hydrogen-dissolved water, and in the case of producing oxygen-dissolved water or ozone-dissolved water by dissolving oxygen gas or ozone gas produced by an electrolysis device in ultrapure water in the gas dissolver. Can be applied similarly. This oxygen-dissolved water or ozone-dissolved water can also be used as cleaning water for the cleaning process in the semiconductor manufacturing factory, like the above-described hydrogen-dissolved water.
[0040]
【The invention's effect】
The present invention is an apparatus for producing gas-dissolved water by supplying gas generated by electrolysis of water to a gas-dissolving apparatus and dissolving the gas in pure water, and the condensed water generated in the gas supply passage of the gas-dissolving apparatus is Since it is configured to be discharged into an apparatus equipped with a gas-liquid separation mechanism, it is not necessary to provide a drain tank in order to discharge condensed water as in the prior art, and there is no need to add a new apparatus. Become. That is, the gas-liquid separation mechanism is necessary for separating the electrolytic gas and water, and is an essential mechanism for configuring the apparatus of the present invention.
[0041]
Therefore, according to the present invention, the basic structure of the gas-dissolved water production apparatus can be used as it is, and the condensed water can be discharged, and there is an advantage that a new configuration is not required for discharging the condensed water. .
[0042]
As a result, according to the present invention, the structure of the entire apparatus is simplified, the manufacturing cost can be reduced, the problem of failure can be solved by the simplified structure, and the apparatus can be advantageously maintained and managed. is there.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a gas-dissolved water production apparatus of the present invention.
FIG. 2 is a schematic diagram showing another embodiment of the apparatus of the present invention.
FIG. 3 is a schematic view showing a conventional gas-dissolved water production apparatus.
[Explanation of symbols]
21, 60 Gas dissolving device 22 Gas-liquid separator 41, 61 Gas supply passage 45 Electrolyzer having gas-liquid separation mechanism

Claims (2)

In a gas-dissolved water production apparatus having a gas dissolving apparatus for dissolving gas generated by electrolysis of water into pure water through a gas permeable membrane ,
A condensed water drain pipe is provided in the gas supply passage of the gas dissolving apparatus, and the condensed water drain pipe is connected to a gas-liquid separator to separate condensed water generated in the gas supply passage of the gas dissolving apparatus. A gas-dissolved water production apparatus characterized by being configured to discharge into a vessel . The gas-liquid separator is provided with a level sensor, and is configured such that water exists in the gas-liquid separator between the upper limit water level and the lower limit water level . Gas dissolved water production equipment.

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