Hydrogen water production device and production method

Abstract

To provide a hydrogen water production apparatus and a production method capable of stably producing hydrogen water having a low hydrogen concentration.SOLUTION: A hydrogen water production device comprising a hydrogen gas generator, a deaerator for deaerating ultrapure water, a gas dissolving device for dissolving hydrogen gas in the ultrapure water deaerated by the deaerator, and a feed line for feeding the hydrogen gas generated by the hydrogen gas generator to the gas dissolving device, wherein the feed line feeds the hydrogen gas to the gas dissolving device at 2 to 45sccm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen water production apparatus and production method for producing hydrogen water for device cleaning used in semiconductor device manufacturing processes, and more particularly to a hydrogen water production apparatus and production method for producing hydrogen gas in a hydrogen gas generator and dissolving the hydrogen gas in ultrapure water in a gas dissolver to produce hydrogen water. [Background technology]

[0002] In the manufacturing process of semiconductor devices, contaminants on the device surface can lead to deterioration of semiconductor device performance and reduced yield on the production line, so the device surface is cleaned with ultrapure water or chemical solutions diluted with ultrapure water to maintain cleanliness.

[0003] In recent years, with the improvement of semiconductor performance, the miniaturization of circuit fabrication technology has progressed significantly, and since even the smallest amount of contaminants can become a problem, the amount of ultrapure water used is increasing year by year.In addition, many of the chemicals used for cleaning have a high environmental impact, which has become a social issue.

[0004] Therefore, functional water has been developed by dissolving gases in ultrapure water or by preparing a very dilute alkaline agent, which is relatively easy to treat. This water can provide extremely high cleaning effectiveness against certain contaminants on device surfaces, and can also provide effects that ultrapure water does not have. In particular, hydrogen water, which is made by dissolving trace amounts of hydrogen gas in ultrapure water, is effective in removing fine particles from wafers and preventing the oxidation of the materials being cleaned. Hydrogen water also has a lower environmental impact than general chemical solutions.

[0005] Conventionally, hydrogen water production devices have been used in which ultrapure water is degassed using a degassing membrane module, and then hydrogen gas is dissolved in the degassed water using a gas dissolving device (Patent Document 1).

[0006] In semiconductor device manufacturing plants, hydrogen gas is usually supplied to hydrogen water production equipment from the factory's house line, but because hydrogen is highly explosive, it is sometimes necessary to supply hydrogen gas to locations where a house line cannot be installed due to this risk.For this reason, a hydrogen gas generator that electrolyzes water to generate and supply hydrogen gas is sometimes incorporated into the hydrogen water production system.

[0007] However, this hydrogen gas generator has the problem that it cannot stably supply hydrogen gas if the supply rate falls below a certain predetermined rate (minimum hydrogen gas generation rate). In other words, with conventional water electrolysis-based hydrogen production devices, if the hydrogen production rate per unit time is reduced below the minimum hydrogen gas generation rate, the hydrogen production rate per unit time becomes unstable. (If the hydrogen production rate per unit time of the hydrogen gas generator falls below the minimum hydrogen gas generation rate (the lower limit of the rated production rate), the hydrogen gas production rate becomes unstable.) Therefore, if the hydrogen production rate per unit time of the hydrogen gas generator is set below the minimum hydrogen gas generation rate in an attempt to produce hydrogen water with a low hydrogen concentration by supplying hydrogen from the hydrogen gas generator to the gas dissolver at a rate less than the minimum hydrogen gas generation rate, the hydrogen gas supply to the gas dissolver becomes unstable, and as a result, the hydrogen concentration of the hydrogen water does not reach the target. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-22599 Summary of the Invention [Problem to be solved by the invention]

[0009] As described above, if an attempt is made to produce hydrogen gas at less than the minimum hydrogen gas generation rate using a hydrogen gas generator, the amount of hydrogen gas produced will become unstable, so the hydrogen gas generator is operated to produce hydrogen gas at or above the minimum hydrogen gas generation rate.

[0010] Therefore, in hydrogen water production equipment equipped with a hydrogen gas generator, the gas is supplied to the gas dissolver at a rate greater than the minimum hydrogen gas generation rate, making it impossible to produce hydrogen water with a low hydrogen concentration. If the hydrogen concentration of hydrogen water is high, excessive cavitation may occur, causing deterioration of wafer surface roughness, or a significant decrease in oxidation-reduction potential may cause surface modification. Therefore, a technology that can stably produce low-concentration hydrogen water is needed.

[0011] An object of the present invention is to provide a hydrogen water production device and production method that can stably produce hydrogen water with a low hydrogen concentration. [Means for solving the problem]

[0012] The gist of the present invention is as follows.

[0013] [1] A hydrogen gas generator; a degassing device for degassing ultrapure water; a gas dissolving device for dissolving hydrogen gas in the ultrapure water degassed by the degassing device; a supply line for supplying the hydrogen gas generated by the hydrogen gas generator to the gas dissolving device; In a hydrogen water production device having The hydrogen water production device is characterized in that the supply line supplies hydrogen gas to the gas dissolver at 2 to 45 sccm.

[0014] [2] The hydrogen gas generator has a minimum hydrogen gas generation rate of 45 sccm or more, The hydrogen water production device of [1] is characterized by being equipped with a non-oxidizing gas addition means that adds a non-oxidizing gas to the excess hydrogen gas generated in the hydrogen gas generator to dilute it to a hydrogen concentration of 4% or less, and then releases it.

[0015] [3] The hydrogen water production apparatus according to [2], wherein the non-oxidizing gas is nitrogen gas.

[0016] [4] A hydrogen gas generator; a degassing device for degassing ultrapure water; a gas dissolving device for dissolving hydrogen gas in the ultrapure water degassed by the degassing device; a supply line for supplying the hydrogen gas generated by the hydrogen gas generator to the gas dissolving device; A method for producing hydrogen using a hydrogen water production device having A method for producing hydrogen water, characterized in that hydrogen gas is supplied to the gas dissolver at a rate of 2 to 45 sccm through the supply line.

[0017] [5] The hydrogen gas generator has a minimum hydrogen gas generation rate of 45 sccm or more, The method for producing hydrogen water according to [4], characterized in that a non-oxidizing gas is added to the excess hydrogen gas generated in the hydrogen gas generator to dilute it to a hydrogen concentration of 4% or less, and then the hydrogen water is released.

[0018] [6] The method for producing hydrogen water according to [5], wherein the non-oxidizing gas is nitrogen gas. [Effects of the Invention]

[0019] In conventional hydrogen water production devices equipped with a hydrogen gas generator, the minimum hydrogen gas generation amount at which the hydrogen gas generator can stably supply gas is determined, and it is not possible to stably produce hydrogen water with a low concentration.In contrast, in the present invention, when producing hydrogen water with a low hydrogen concentration, hydrogen gas is produced using the hydrogen gas generator at a generation amount equal to or greater than the minimum hydrogen gas generation amount, and a portion of this hydrogen gas is supplied to the gas dissolving device, making it possible to stably produce hydrogen water with a low hydrogen concentration.

[0020] According to the present invention, even when producing low-concentration hydrogen water or hydrogen water at a low flow rate, which requires a low supply of hydrogen gas, the amount of hydrogen gas supplied is stabilized, so hydrogen water can be stably produced at the target concentration. For example, even hydrogen water with a hydrogen concentration of about 0.1 ppm can be stably produced at a constant hydrogen concentration.

[0021] In one embodiment of the present invention, excess hydrogen gas that is not supplied to the gas dissolver is mixed with nitrogen gas so that the hydrogen gas concentration is 4% or less, and then discharged.

[0022] For example, when a hydrogen water production device equipped with a conventional hydrogen gas generator supplies hydrogen water at 5 L / min, it is not possible to produce hydrogen water with a concentration of less than 0.9 ppm, and if surface modification occurs when the oxidation-reduction potential is below -300 mV, the desired cleaning effect cannot be achieved.

[0023] The present invention can produce hydrogen water with a constant hydrogen concentration of 0.9 ppm or less, and this hydrogen concentration can be changed as needed. For example, by setting the supply rate from the hydrogen gas generator to 11 sccm, it is possible to supply 0.2 ppm hydrogen water at 5 L / min, and obtain the particle removal effect while maintaining the oxidation-reduction potential at approximately 50 mV. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a configuration diagram of a hydrogen water production device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment will be described with reference to FIG.

[0026] 1, ultrapure water is supplied to a liquid phase section 2a of a degassing device 2 through a pipe 1 having a valve 1v. A flow meter 3 is provided in the pipe 1.

[0027] The degassing device 2 is divided into a liquid phase section 2a and a gas phase section 2b by a degassing membrane 2m, and a vacuum pump 5 is connected to the gas phase section 2b. The degassed ultrapure water produced by degassing in the liquid phase section 2a is supplied from the liquid phase section 2a to a gas dissolver 7 via a pipe 6.

[0028] Degassed ultrapure water from pipe 6 is supplied into the liquid phase section 7a of the gas dissolver 7. The gas dissolver 7 is divided into the liquid phase section 7a and the gas phase section 7b by a gas permeable membrane 7m. Hydrogen gas is supplied to the gas phase section 7b at 2 to 45 sccm from a hydrogen gas generator 8 via pipe 9 and a gas injection rate controller (MFC: mass flow controller) 10. (1 sccm is 1 cm at 0°C and 1 atmospheric pressure.) 3 The gas phase section 7b has a valve 7v, which is normally closed but is opened as required.

[0029] Hydrogen gas permeates from the gas phase portion 7b through the gas permeable membrane 7m and dissolves in the degassed ultrapure water in the liquid phase 7a, producing hydrogen water, which is taken out through the pipe 12.

[0030] One end of pipe 14 for branching off excess hydrogen gas is connected to pipe 9. The other end of pipe 14 is connected to pipe 16 for gas discharge via gas injection amount controller 15. Nitrogen gas can be introduced into pipe 16 via pipe 17, flow rate adjustment valve 18, and pipe 19. Pipe 19 is provided with a flow meter 20. A hydrogen gas detector 21 is provided to detect the hydrogen concentration of the exhaust gas (gas in which hydrogen is diluted with nitrogen gas) flowing out from pipe 14. The hydrogen gas flow rate control mechanism may be any device capable of controlling the hydrogen gas flow rate. One embodiment of the hydrogen gas flow rate control mechanism uses a single line to adjust the flow rate using mass flow. Another embodiment uses multiple lines that branch off to adjust the gas flow rate. These two methods allow for minute adjustments of the hydrogen gas flow rate. When adjusting a gas flow rate of a few sccm, it is preferable to use a branched line.

[0031] The feedwater (ultrapure water) flow rate detected by the flow meter 3 is input to the control device 23. The control device 23 controls the gas injection amount controller 10 so that an amount of hydrogen gas corresponding to the ultrapure water flow rate and the target hydrogen concentration of the hydrogen water is supplied to the gas phase section 7b.

[0032] The hydrogen gas generator 8 is a type that generates hydrogen by electrolyzing water, and produces hydrogen gas at a production rate equal to or greater than the minimum hydrogen gas production rate. When the amount of hydrogen gas F supplied to the gas phase section 7b is equal to or greater than the minimum hydrogen gas production rate, the hydrogen gas generator 8 is operated to produce F or more. The minimum hydrogen gas production rate of the hydrogen gas generator 8 is preferably 45 sccm or more, more preferably 45 sccm to 1000 sccm, and even more preferably 45 sccm to 500 sccm.

[0033] When the amount of gas F supplied to the gas phase section 7 becomes less than the minimum amount of hydrogen gas generated, the hydrogen gas generator 8 is operated at the minimum amount of hydrogen gas generated or at a production amount slightly greater than the minimum amount of hydrogen gas generated.

[0034] If hydrogen is produced in excess of the supply gas amount F, the excess hydrogen gas is caused to flow into pipe 16 by gas injection amount controller 15. At this time, nitrogen gas is supplied to pipe 16 while adjusting the flow rate with valve 18 so that the hydrogen concentration in the exhaust gas discharged from pipe 16 is 4% or less. If the hydrogen concentration in the exhaust gas is 4% or less, there is no risk of explosion and it is safe.

[0035] In this way, even when the amount of hydrogen supplied to gas phase 7b is set below the minimum hydrogen gas generation amount to produce hydrogen water with a low hydrogen concentration, the amount of hydrogen produced can be stabilized by operating hydrogen gas generator 8 so that the amount of hydrogen produced is equal to or greater than the minimum hydrogen gas generation amount. Furthermore, when the amount of hydrogen supplied to gas phase 7b is set below the minimum hydrogen gas generation amount to produce hydrogen water with a low hydrogen concentration, excess hydrogen gas is discharged through pipes 14 and 16. In this case, the hydrogen gas is diluted with nitrogen gas to a hydrogen concentration of 4% or less before being discharged, which is safe.

[0036] As described above, the hydrogen water production device of the present invention has the following: 1. A degassing device that removes dissolved gases from ultrapure water. 2. A gas dissolving device that dissolves a specified amount of hydrogen gas to maintain a constant dissolved hydrogen concentration. 3. A mechanism that controls the amount of hydrogen gas supplied to the gas dissolution device based on the flow rate measured by the cleaning solution flow rate monitoring mechanism. (The flow meter and mass flow controller are connected to the control system.) 4. Hydrogen gas generator to supply hydrogen to the gas dissolution device 5. A mechanism that produces hydrogen gas so that the amount of hydrogen gas generated by the hydrogen gas generator does not fall below the minimum amount when hydrogen gas is supplied to the gas dissolution device at a rate below the minimum amount, and dilutes the excess hydrogen gas with nitrogen gas to below the lower explosion limit (4%) and exhausts it.

[0037] The hydrogen production amount of the hydrogen gas generator may always be set to a minimum hydrogen gas production amount or more, and excess hydrogen gas may always be diluted with nitrogen gas and exhausted. Also, there may be two or more mechanisms for exhausting excess hydrogen gas. [Example]

[0038] In the hydrogen water production apparatus shown in FIG. 1, the following hydrogen gas generator 8, degasser 2, and gas dissolver were used.

[0039] Hydrogen gas generator: Maxell, solid polymer electrolyte membrane water electrolysis hydrogen gas generator (HGU-24E), minimum hydrogen gas generation rate 45sccm Degassing device: 3M, EXF-4 x 28 Gas dissolving device: 3M, EXF-4 x 28

[0040] <Test conditions> The supply method was evaluated assuming that hydrogen water would be produced using this cleaning water production equipment and supplied to semiconductor manufacturing process equipment. The evaluation items were the oxidation-reduction potential of the hydrogen water and its concentration stability. The oxidation-reduction potential was measured with an ORP meter, and hydrogen gas was measured with a DH meter.

[0041] If the hydrogen concentration in the produced hydrogen water remained stable at the set concentration for 60 minutes or more, it was evaluated as good, and if the hydrogen concentration did not rise or stabilize, it was judged as poor.

[0042] [Driving example 1] The target hydrogen concentration of the hydrogen water was set to 0.1 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 6 sccm. Oxidation-reduction potential: approx. 100 mV Hydrogen concentration stability: Even after 60 minutes, the hydrogen concentration remained at 0.1±0.02 ppm, which was good.

[0043] [Driving example 2] The target hydrogen concentration of the hydrogen water was set to 0.3 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 17 sccm. Oxidation-reduction potential: approx. 0 mV Hydrogen concentration stability: Even after 60 minutes, the hydrogen concentration remained at 0.3±0.05 ppm, which was good.

[0044] [Operation example 3] The target hydrogen concentration of the hydrogen water was set to 0.5 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 28 sccm. Oxidation-reduction potential: approx. -100mV Hydrogen concentration stability: Even after 60 minutes, the hydrogen concentration remained at 0.5±0.05 ppm, which was good.

[0045] [Operation example 4] The target hydrogen concentration of the hydrogen water was set to 0.7 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 39 sccm. Oxidation-reduction potential: approx. -200mV Hydrogen concentration stability: Even after 60 minutes, the hydrogen concentration remained at 0.7±0.05 ppm, which was good.

[0046] [Operation example 5] The target hydrogen concentration of the hydrogen water was set to 0.5 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 1 sccm. Oxidation-reduction potential: approx. 200 mV Hydrogen concentration stability: The hydrogen concentration did not rise to the set concentration, and the concentration decreased over time, resulting in poor stability.

[0047] [Driving example 6] The target hydrogen concentration of the hydrogen water was set to 0.9 ppm, the flow rate of the hydrogen water was set to 5 L / min, and hydrogen gas was supplied at 50 sccm. Oxidation-reduction potential: approx. -350mV Hydrogen concentration stability: Even after 60 minutes, the hydrogen concentration remained at 0.9±0.05 ppm, which was good.

[0048] These results are summarized in Table 1.

[0049] [Table 1]

[0050] As shown in Table 1, when hydrogen gas is supplied from the hydrogen gas generator to the gas dissolver, excess hydrogen gas is produced so that the hydrogen gas production rate of the hydrogen gas generator does not fall below the minimum hydrogen gas production rate, and the excess hydrogen gas is discharged. This allows for a stable supply of hydrogen water even when low-concentration hydrogen water is required from semiconductor manufacturing process equipment. Furthermore, for materials whose surface properties change at a certain oxidation-reduction potential, conventional hydrogen water generators cannot set a wide range of hydrogen water concentrations, which can lead to surface deterioration. In contrast, the present invention allows for a wide range of hydrogen water concentrations, making it possible to clean the material without damaging the surface. [Explanation of symbols]

[0051] 2 Degassing device 5. Vacuum pump 7 Gas dissolving device 8. Hydrogen gas generator 10,15 Gas injection amount controller 23 Control device

Claims

1. a hydrogen gas generator; a degassing device for degassing ultrapure water; a gas dissolving device for dissolving hydrogen gas in the ultrapure water degassed by the degassing device; a supply line for supplying the hydrogen gas generated by the hydrogen gas generator to the gas dissolving device; In a hydrogen water production device having The hydrogen gas generator has a minimum hydrogen gas generation rate of 45 sccm or more, the supply line supplies hydrogen gas to the gas dissolution device at 2 to 45 sccm; A hydrogen water production device characterized by being equipped with a non-oxidizing gas addition means that adds a non-oxidizing gas to the excess hydrogen gas generated in the hydrogen gas generator to dilute it to a hydrogen concentration of 4% or less and then releases it.

2. 2. The hydrogen water generating apparatus according to claim 1, wherein the non-oxidizing gas is nitrogen gas.

3. A hydrogen water production apparatus as described in claim 1 or 2, wherein the hydrogen water in which hydrogen gas is dissolved in ultrapure water produced by the gas dissolution device is hydrogen water for device cleaning used in semiconductor device manufacturing processes.

4. a hydrogen gas generator; a degassing device for degassing ultrapure water; a gas dissolving device for dissolving hydrogen gas in the ultrapure water degassed by the degassing device; a supply line for supplying the hydrogen gas generated by the hydrogen gas generator to the gas dissolving device; A method for producing hydrogen using a hydrogen water production device having The hydrogen gas generator has a minimum hydrogen gas generation rate of 45 sccm or more, The supply line supplies hydrogen gas to the gas dissolver at a rate of 2 to 45 sccm; A method for producing hydrogen water, characterized in that a non-oxidizing gas is added to the excess hydrogen gas generated in the hydrogen gas generator to dilute it to a hydrogen concentration of 4% or less, and then the hydrogen water is released.

5. 5. The method for producing hydrogen water according to claim 4, wherein the non-oxidizing gas is nitrogen gas.

6. A method for producing hydrogen water as described in claim 4 or 5, wherein the hydrogen water in which hydrogen gas is dissolved in ultrapure water produced by the gas dissolution device is hydrogen water for cleaning devices used in semiconductor device manufacturing processes.

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