JP2013128870A - Gas dissolved water producing apparatus and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas dissolved water producing apparatus in which gas solubility directly after the start of feed, and further, specific resistance value are stable even if an operation is intermittently performed.SOLUTION: The gas dissolved water producing apparatus 1 is provided with: a pure water feed pipe 3 of intermittently feeding pure water by a water feed valve 2; a gas dissolution part 4 connected with the pure water feed pipe 3 and inserted with a gas feed pipe 7; and a gas flow rate regulation apparatus 6 of regulating the feed amount of the gas; wherein the gas is injected into the pure water via the gas feed pipe 7 to produce gas dissolved water in which the gas is dissolved at a fixed concentration. The apparatus includes a controller 11 of stopping the injection of the gas upon the closing of the water feed valve 2, and making the setting of the feed amount of the gas to the setting in which the feed amount of the gas is larger than that in the ordinary case for a fixed time and thereafter making the setting into the setting in which the feed amount is ordinary upon the release of the water feed valve 2.

Description

  The present invention relates to a gas-dissolved water production apparatus and a gas-dissolved water production method that eliminate fluctuations in gas solubility during intermittent operation.

  Conventionally, pure water is used for cleaning a semiconductor wafer or the like in a manufacturing process of a semiconductor device. For example, in the substrate cleaning process, particles attached to the surface of the substrate are removed by spraying a cleaning liquid such as pure water onto the substrate.

  By the way, it is known that when pure water is discharged at a high pressure or the polishing brush is rotated at a high speed, the specific surface of the substrate is charged because the specific resistance of pure water is high. When the amount of charge on the substrate surface is increased, there are problems that particles are reattached after cleaning, and an oxide film and a metal thin film forming a semiconductor element formed on the wafer are destroyed by electrostatic discharge.

  As a measure for preventing such destruction of the semiconductor element, it has been studied to reduce the electrical resistivity of pure water and suppress the generation of static electricity.

For example, Patent Document 1 discloses a method for preventing charging of the substrate surface by reducing the electrical resistivity by dissolving carbon dioxide (CO ₂ ) gas in ultrapure water that is treated water.

In this way, hydrogen carbonate ions are dissociated and dissolved in so-called carbonated water in which carbon dioxide (CO ₂ ) gas is dissolved in ultrapure water, but the electrical resistivity can be lowered by the hydrogen carbonate ions. It is possible to reduce the electrostatic charge on the wafer and prevent the semiconductor element from being destroyed by electrostatic discharge.

  Further, at the stage after the drying process after cleaning, the carbon dioxide gas (dissolved in the carbonated water) disappears as a gas on the wafer surface, and there is an advantage that no trace of impurity residue is left.

  Further, Patent Document 2 discloses a device for generating microbubbles and suppressing coalescence of bubbles to dissolve in water in order to stabilize the dissolved gas concentration of such gas-dissolved water. Such an apparatus is an apparatus in which liquid introduction parts having different flow cross-sectional areas are coupled by a conical coupling part, and gas dissolved water in which gas bubbles are completely dissolved is generated.

  In recent years, gases other than carbon dioxide, for example, dissolved water in which hydrogen, ozone, oxygen, and nitrogen gas are dissolved are also widely used in semiconductor manufacturing processes.

JP 2008-153322 A Japanese Patent Laid-Open No. 2003-230824

  In general, in the production of dissolved gas water, it is necessary to keep the solubility constant. However, at the start of operation of the gas-dissolved water production apparatus, the solubility fluctuates violently, and it is extremely difficult to suppress the fluctuation of the solubility, and thus the apparatus must be continuously operated. This has a problem of deteriorating operating efficiency.

  The present invention conducted a highly accurate experiment using a small device aiming at supplying pure water with stable gas solubility of the gas dissolved water production apparatus. It has been found that gas-dissolved water with low time solubility is produced, and that gas-dissolved water with high gas solubility is produced for a certain period of time when operation is stopped.

  As a result of further investigations addressing this problem, the present inventors have found that this phenomenon is because pure water is an incompressible fluid, whereas the dissolved gas is a compressible fluid. The responsiveness to the opening / closing operation of the opening / closing valve is different. At the start of operation, there is a time delay in the gas injection with respect to the start of the supply of pure water. Conversely, even when the supply of pure water is stopped, In this case, it was confirmed that this was caused by the continuous injection due to the residual pressure in the supply pipe, and when the operation was stopped for a long time, the gas in the gas supply pipe was dissolved in pure water and gradually purified. It has been found that the intrusion of water into the gas supply pipe also changes the specific resistance value at the start of operation, and the present invention has been completed.

  A gas-dissolved water production apparatus according to the present invention includes a pure water supply pipe that supplies pure water intermittently by a water supply valve, a gas dissolution section that is connected to the pure water supply pipe and has a gas supply pipe inserted therein, A gas flow rate adjusting device for adjusting a supply amount, injecting a gas into the pure water via the gas supply pipe, and manufacturing a gas dissolved water in which the gas is dissolved at a constant concentration; A control device that stops the supply of the gas when the water supply valve is closed, and sets the supply amount of the gas to a higher supply amount than a normal time for a certain period of time when the water supply valve is opened, and then sets the normal supply amount It is characterized by having.

  Thus, when the water supply valve is opened, the supply of pure water to the gas dissolving part and the supply of gas are increased by increasing the flow rate of the gas supplied from the gas supply pipe from the normal flow rate for a certain period of time. At the same time, the specific resistance value of the obtained gas-dissolved water can be made constant.

  Further, the gas dissolved water production apparatus of the present invention has a blow valve between the gas supply pipe and the gas flow control device, and opens the blow valve for a certain time when the water supply valve is closed, It is preferable to blow the gas.

  In this way, by blowing the gas remaining in the gas supply pipe when the water supply valve is closed, the gas in the gas supply pipe is prevented from being injected into the pure water due to residual pressure while the water supply valve is closed. The specific resistance value of the gas-dissolved water can be stabilized.

  More specifically, it is preferable to have a stop valve that is closed when the water supply valve is closed and opened when the water supply valve is opened, downstream of the gas dissolving section. When the water supply valve is closed, the stop valve is closed to prevent the gas in the gas supply pipe from flowing into the pure water due to residual pressure, and the pure water flows back into the gas supply pipe when the water supply valve is closed for a long period of time. Can also be prevented.

  More specifically, the gas dissolving portion is configured such that the gas supply pipe is inserted to the center of the T-shaped pipe, and the gas supply direction and the pure water supply direction are orthogonal to each other. A mold pipe is preferred.

  Moreover, the flow rate of the gas-dissolved water is not particularly limited, but is preferably 0.1 to 10 L / min. 0.1-3 L / min is more preferable, and 0.1-1 L / min is further more preferable.

  The gas-dissolved water production method of the present invention includes a pure water supply pipe that intermittently supplies pure water by a water supply valve, a gas dissolution part that is connected to the pure water supply pipe and has a gas supply pipe inserted therein, A gas flow rate adjusting device for adjusting a supply amount, injecting a gas into the pure water via the gas supply pipe, and manufacturing a gas dissolved water in which the gas is dissolved at a constant concentration; When the water supply valve is closed, the supply of the gas is stopped, and when the water supply valve is opened, the setting of the supply amount of the gas is set to a setting higher than the normal amount for a certain time, and then the normal supply amount is set. Features.

  In the present invention, “pure water” is water having a specific resistance of 10 MΩ · cm or more and TOC (total organic carbon) of 0.1 mg / L or less, and “ultra pure water” has a specific resistance of 17 MΩ. -Water with cm or more and TOC (total organic carbon) of 10 μg / L or less.

  A pure water supply pipe for supplying pure water intermittently by a water supply valve, a gas dissolving part to which the pure water supply pipe is connected and a gas supply pipe is inserted, and a gas flow rate adjusting device for adjusting the supply amount of the gas; In a gas-dissolved water production apparatus for producing gas-dissolved water in which a gas is injected into the pure water through the gas supply pipe and the gas dissolves at a constant concentration, the solubility of the water supply at the start and stop is changed. Disclosed is an apparatus and a method for producing gas-dissolved water that is suppressed and always has a stable specific resistance value.

FIG. 1 is a block diagram showing a gas-dissolved water production apparatus according to an embodiment of the present invention. FIG. 2 is a side sectional view schematically showing a gas dissolving part of the gas dissolved water producing apparatus according to one embodiment of the present invention. FIG. 3 is a graph of specific resistance values of gas-dissolved water produced using the gas-dissolved water producing apparatus according to one embodiment of the present invention. FIG. 4 is a graph of specific resistance values of gas-dissolved water produced using the gas-dissolved water producing apparatus according to one embodiment of the present invention. FIG. 5 is a graph of specific resistance values of gas-dissolved water produced using the gas-dissolved water producing apparatus according to one embodiment of the present invention. FIG. 6 is a graph of specific resistance values of gas-dissolved water produced using the gas-dissolved water producing apparatus according to one embodiment of the present invention. FIG. 7 is a graph of the specific resistance value of the dissolved gas produced using the dissolved gas production apparatus as a comparative example of the present invention. FIG. 8 is a graph of the specific resistance value of the gas dissolved water manufactured using the gas dissolved water manufacturing apparatus which is another comparative example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A gas-dissolved water production apparatus 1 according to an embodiment of the present invention shown in FIG. 1 includes a pure water supply pipe 3 that intermittently supplies pure water by opening and closing a water supply valve 2, and an upright state of the pure water supply pipe 3. An inserted T-shaped joint 4, an on-off valve 5, a gas flow rate adjusting device 6 that changes the gas supply amount, a gas flow rate adjusting device 6, and a gas supply pipe 7 that connects the lower part 4 a of the straight pipe portion of the T-shaped joint 4; Blow valve 8 inserted in gas supply pipe 7, pure water outflow pipe 9 connected to the top of the T-shaped joint, stop valve 10 inserted in pure water outflow pipe 9, and water supply valve 2, gas flow rate adjustment A control device 11 for opening / closing and controlling the device 6, the blow valve 8 and the stop valve 10 is provided.

  The gas supplied at a constant flow rate from the gas supply pipe 7 is mixed and dissolved in the pure water supplied from the pure water supply pipe 3 inside the T-shaped joint 4, and is supplied from the upper outlet 4 b to the pure water outflow pipe 9. Used after being drained.

  FIG. 2 is a side sectional view schematically showing the gas dissolving part of the present embodiment. As the gas dissolving part, in addition to the T-type joint 4, those generally used for gas-liquid mixing are suitable.

  In this embodiment, the gas supply pipe 7 is connected to the lower part 4a of the T-shaped joint 4, and the pure water outflow pipe 9 is connected to the upper part 4b, but the pure water outflow pipe is supplied to the lower part 4a and the gas is supplied to the upper part 4b. A tube 7 may be connected.

  In this apparatus, the pure water supply pipe 3 has an inner diameter of φ1 to 5 mm, the flow rate of pure water is 0.1 to 1 L / min, the inner diameter of the gas supply pipe 7 is φ0.1 to 0.5 mm, and is opened and closed. The internal volume from the valve 5 to the nozzle tip of the gas supply pipe 7 is about 1 to 10 mL.

  A gas, for example, carbon dioxide gas is supplied from the gas supply pipe 7 by a mass flow controller (MC-5SCCM, manufactured by ALICAT) as the gas flow rate control device 6. The supply pressure of the supplied carbon dioxide gas is 0.15 MPa, and the flow rate is 0.05 to 4 mL / min (at 20 ° C. and 1 atm). The on-off valve 5 is a check valve (SS-2C-1, manufactured by Swagelok, SUS), and the water supply valve 2 and the stop valve 10 are air driven valves (AMD01-6UP-4, manufactured by CKD, outer diameter). The blow valve 8 is an air driven valve (AMDZ1-6BUS-2, manufactured by CKD, outer diameter 6 mm, material PFA) or the like.

  The water supply valve 2, the gas flow rate adjusting device 6 (mass flow controller), the blow valve 8 and the stop valve 10 are opened / closed and operated by the control device 11 at a predetermined timing.

  In the gas dissolved water manufacturing apparatus 1 of the present embodiment, when the water supply is stopped, the setting of the gas flow rate adjusting device 6 (mass flow controller) is set to 0, the water supply valve 2 is closed, and the blow valve 8 is instantaneously opened and then closed. . When the operation is resumed, the set flow rate of the gas flow rate adjusting device 6 (mass flow controller) is set to about 2 to 100 times the normal supply amount setting simultaneously with the opening of the water supply valve 2.

  By such an operation, when the water supply valve 2 is opened, pure water and gas can be simultaneously supplied to the T-shaped joint 2 to keep the concentration of the obtained gas dissolved water constant and to stabilize the specific resistance value. The gas supply amount and supply time when the water supply valve 2 is opened can be set as appropriate depending on the characteristics of the flow rate adjusting device 6, the length and internal volume of the gas supply pipe 7, and are, for example, 2 to 100 times the normal flow rate. The supply amount is set to a degree, and the supply time is preferably 1 to 10 seconds.

  When the water supply is stopped, that is, when the water supply valve 2 is closed, the setting of the gas flow rate adjusting device 6 (mass flow controller) is preferably set to 0, and the blow valve 8 is opened to blow the gas in the gas supply pipe 7. By this operation, after the water supply is stopped, a part of the gas remaining in the gas supply pipe 7 is supplied to the T-shaped joint 4 by the residual pressure and is dissolved in pure water, so that dissolved water having a high concentration is generated in the T-shaped joint 4. This prevents the high-concentration dissolved water that stays at the start of water supply from flowing out from the T-shaped joint 4 to the pure water outflow pipe 9, and the specific resistance value of the resulting gas-dissolved water is prevented from slightly decreasing. Can do. Further, since the inside of the gas supply pipe 7 is depressurized, even if the water supply valve 2 is closed for a long time, the gas in the gas supply pipe 7 is gradually dissolved in pure water and the pure water flows back into the gas supply pipe 7. There is no fear.

  The time during which the blow valve 8 is opened when the water supply valve 2 is closed is the time during which the inside of the gas supply pipe 7 can be depressurized below the supply pressure of pure water. It is determined from the internal volume and can be set as appropriate. However, when the opening time of the blow valve 8 is too long, the pure water may flow back to the gas supply pipe 7, which is not preferable. Therefore, specifically, the opening time of the blow valve 8 is, for example, 0.01 seconds to 2 seconds, preferably 0.01 seconds to 1 second.

  Further, when the water supply is stopped for a long time and then restarted, the gas in the gas supply pipe 7 may be dissolved in the pure water and the pure water may enter the gas supply pipe 7. Due to this phenomenon, at the start of water supply, the time at which gas starts to be supplied to the T-shaped joint 4 is substantially delayed by the amount of ingress of pure water, resulting in dissolved water having a low gas concentration. The specific resistance value of water temporarily increases. That is, by temporarily opening the blow valve 8 when the water supply is stopped, if the pressure in the gas supply pipe 7 is reduced below the pure water supply pressure, the amount of pure water entering the gas supply pipe 7 is substantially reduced. It can be kept constant, and a temporary increase in specific resistance value at the start of water supply due to the influence of water supply stop for a long time can be prevented.

The same effect can be obtained by closing the stop valve 10 without opening and closing the blow valve 8 when the water supply is stopped. Further, the same effect can be obtained even when the opening and closing of the blow valve 8 and the closing of the stop valve 10 are used in combination.
Such a cycle of stopping and restarting the water supply can be arbitrarily changed, for example, depending on the use status of the dissolved gas, such as restarting for a few seconds to several days.

  Examples of the gas to be used include carbon dioxide (carbonic acid) gas, nitrogen gas, hydrogen gas, ozone gas, oxygen gas and the like, and carbon dioxide gas is preferable.

  The gas-dissolved water producing apparatus according to an embodiment of the present invention is particularly preferably used when producing carbon dioxide gas-dissolved water having a specific resistance value of 0.1 to 2 MΩ · cm. In addition, carbon dioxide gas-dissolved water having a specific resistance value of 0.1 to 2 MΩ · cm can be manufactured by the gas-dissolved water manufacturing method of the present invention.

  Next, examples of the present invention will be described.

  The gas-dissolved water production apparatus 1 used in this example is the apparatus shown in FIG. 1, and the pure water and the experimental apparatus used are as follows.

[Pure water] Specific resistance 18MΩ · cm
[Flow rate of pure water] 0.2L / min
[Gas to be dissolved] Carbon dioxide gas [Flow rate of carbon dioxide gas] 0.08 mL / min (at 20 ° C. and 1 atm)
[Supply pressure of carbon dioxide gas] 0.15 MPa
[Gas supply pipe 7] Inner diameter 0.13 mm, volume 3 mL
[Water temperature] 20 ℃
[Gas flow rate control device 6] MC-5SCCM, manufactured by ALICAT [Resistivity measuring device] HE-480R manufactured by Horiba Advanced Techno Co., Ltd.

Example 1
In the state where the gas dissolved water is manufactured, the setting of the gas flow control device 6 (mass flow controller) is set to 0, the water supply valve 2 is closed, the blow valve 8 is opened for 0.1 second, and the gas supply pipe 7 is opened. The remaining carbon dioxide gas was blown to stop the operation. After 1 minute, the water supply valve 2 was opened again, and at the same time, the setting of the gas flow rate adjusting device 6 was set to a flow rate of 2.4 mL / min for 3 seconds, and then the operation was resumed by returning to the normal setting.
At this time, the specific resistance value of the carbon dioxide dissolved water flowing out from the pure water outflow pipe 9 after the water supply valve was opened was measured and shown in FIG.

(Example 2)
In Example 1, the blow valve 8 was kept closed when the operation was stopped. The other operations were the same as in Example 1.
At this time, the specific resistance value of the carbon dioxide dissolved water flowing out from the pure water outflow pipe 9 after opening the water supply valve was measured and shown in FIG.

(Example 3)
In Example 1, when the operation was stopped, the stop valve 10 was closed and the blow valve 8 was kept closed. Further, the stop valve 10 was opened together with the water supply valve 2 when the operation was resumed. The other operations were the same as in Example 1.
At this time, the specific resistance value of the carbon dioxide-dissolved water flowing out from the pure water outflow pipe 9 after opening the water supply valve was measured and shown in FIG.

(Comparative Example 1)
In Example 1, the blow valve 8 was kept closed when the operation was stopped, and the setting of the gas flow rate adjusting device 6 was kept normal when the operation was started. The other operations were the same as in Example 1.
At this time, the specific resistance value of the carbon dioxide-dissolved water flowing out from the pure water outflow pipe 9 after opening the water supply valve was measured and shown in FIG.
At this time, when the inside of the T-type pipe was made of glass and the inside was observed, it was observed that bubbles were generated little by little from the tip of the gas supply pipe 7 when the water supply was stopped. Moreover, the time from the restart of operation to the stabilization of the specific resistance value was 135 seconds.

Example 4
In the state where the gas dissolved water is being manufactured, the setting of the gas flow control device 6 (mass flow controller) was set to 0, and the water supply valve 2 and the stop valve 10 were simultaneously closed to stop the operation. The blow valve 8 remained closed. At the time of restarting operation, the water supply valve 2 and the stop valve 10 were opened again, and at the same time, the gas flow rate adjusting device 6 was set to a flow rate of 2.4 mL / min for 3 seconds, and then returned to the normal setting. First, water was supplied for 3 minutes, and then stop and water supply were repeated. The water supply time at that time was gradually increased to 1 minute, and the stop time was gradually increased to 1, 5, 10, and 20 minutes.
At this time, the specific resistance value of the carbon dioxide-dissolved water flowing out from the pure water outflow pipe 9 was measured and shown by a solid line in FIG.

(Comparative Example 2)
When the operation was stopped, the same operation as in Example 4 was performed except that the stop valve 10 was kept open.
At this time, the specific resistance value of the carbon dioxide-dissolved water flowing out from the pure water outflow pipe 9 was measured and shown by a solid line in FIG. It was confirmed that the specific resistance value tends to fluctuate with an increase in the stop time.

  DESCRIPTION OF SYMBOLS 1 ... Gas dissolved water manufacturing apparatus, 2 ... Water supply valve, 3 ... Pure water supply pipe, 4 ... T type joint, 4a ... T type joint lower part (inlet), 4b ... T type joint upper part (outlet), 5 ... Open / close valve, 6 ... gas flow rate adjusting device, 7 ... gas supply pipe, 8 ... blow valve, 9 ... pure water outflow pipe, 10 ... stop valve, 11 ... control device

Claims (6)

A pure water supply pipe for supplying pure water intermittently by a water supply valve, a gas dissolving part to which the pure water supply pipe is connected and a gas supply pipe is inserted, and a gas flow rate adjusting device for adjusting the supply amount of the gas; In a gas dissolved water production apparatus for producing gas dissolved water in which gas is injected into the pure water through the gas supply pipe and the gas is dissolved at a constant concentration,
Control that stops the supply of the gas when the water supply valve is closed, and sets the supply amount of the gas to a setting higher than normal for a certain period of time when the water supply valve is opened, and then sets the normal supply amount A gas-dissolved water production apparatus comprising an apparatus. A blow valve between the gas supply pipe and the gas flow control device;
The gas dissolved water production apparatus according to claim 1, wherein the blow valve is opened for a certain period of time when the water supply valve is closed, and the gas in the gas supply pipe is blown.   The gas dissolved water production apparatus according to claim 1 or 2, further comprising a stop valve that is closed when the water supply valve is closed and opened when the water supply valve is opened, downstream of the gas dissolving portion.   The gas dissolving part is a T-shaped pipe configured such that the gas supply pipe is inserted to the center of the T-shaped pipe, and the gas supply direction and the pure water supply direction are orthogonal to each other. The gas-dissolved water production apparatus according to any one of claims 1 to 3.   The gas dissolved water production apparatus according to any one of claims 1 to 4, wherein a flow rate of the gas dissolved water is 0.1 to 10 L / min. A pure water supply pipe for supplying pure water intermittently by a water supply valve, a gas dissolving part to which the pure water supply pipe is connected and a gas supply pipe is inserted, and a gas flow rate adjusting device for adjusting the supply amount of the gas; In a gas dissolved water production apparatus for producing gas dissolved water in which gas is injected into the pure water through the gas supply pipe and the gas is dissolved at a constant concentration,
When the water supply valve is closed, the gas supply is stopped, and when the water supply valve is opened, the gas supply amount is set to a higher supply amount than normal for a certain period of time, and then the normal supply amount is set. A gas-dissolved water production method characterized by

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