Ultrapure water production system and ultrapure water supply apparatus

Abstract

To improve the quality of ultrapure water to be supplied to a use point.SOLUTION: The ultrapure water production system includes a secondary pure water production device 10 for producing ultrapure water by treating primary pure water, and an ultrapure water supply device 20 for treating the ultrapure water supplied from the secondary pure water production device 10 and supplying the ultrapure water to a use device 30, wherein the anion concentration and the metal concentration of the ultrapure water produced by the secondary pure water production device 10 are less than 10 ng / L, and a pipe from an ion-exchange device 14 provided in the secondary pure water production device 10 to the ultrapure water supply device 20 is made of a material other than a fluorine resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrapure water manufacturing system and an ultrapure water supply apparatus. [Background technology]

[0002] Ultrapure water supplied from an ultrapure water production system is pumped through supply piping that connects the ultrapure water production system to a point of use (hereinafter referred to as a "use point") where the ultrapure water is used, and then supplied to the use point. As a result, there is a risk that the quality of the ultrapure water may deteriorate due to impurities eluting from the piping. To address this issue, a technology has been considered that uses a type of fluororesin called PVDF (polyvinylidene fluoride), which has low elution, as the material for the supply piping (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7033691 Summary of the Invention [Problem to be solved by the invention]

[0004] Even with PVDF piping, there is a risk of trace impurities eluting. If trace impurities elute, the quality of the ultrapure water will deteriorate as it is supplied to the point of use. This deteriorated water quality may fall below the required quality for ultrapure water used in cutting-edge semiconductor manufacturing. As such, the above-mentioned technology has the problem of being unable to meet the recent demand for even higher purity of ultrapure water (suppression of water quality deterioration).

[0005] An object of the present invention is to provide an ultrapure water manufacturing system and an ultrapure water supply apparatus that can improve the quality of ultrapure water supplied to a point of use. [Means for solving the problem]

[0006] The ultrapure water producing system of the present invention comprises: a secondary pure water production device that processes primary pure water to produce ultrapure water; an ultrapure water supplying device that treats the ultrapure water supplied from the secondary pure water producing device and supplies the treated water to a device that uses the treated water; The anion concentration and metal concentration of the ultrapure water produced by the secondary pure water production apparatus are less than 10 ng / L, The piping from the ion exchange device provided in the secondary pure water production system to the ultrapure water supply system is made of a material other than fluororesin.

[0007] The ultrapure water supply apparatus of the present invention further comprises: This system has the function of reducing the concentration of impurities contained in ultrapure water supplied from an ion exchange device installed in a secondary pure water production system that processes primary pure water to produce ultrapure water with anion and metal concentrations of less than 10 ng / L via piping made of a material other than fluororesin. [Effects of the Invention]

[0008] In the present invention, the quality of ultrapure water supplied to a point of use can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an embodiment of an ultrapure water producing system of the present invention. [Figure 2(A)] FIG. 2 is a diagram showing a first example of the internal configuration of the ultrapure water supply apparatus shown in FIG. [Figure 2(B)] 1. FIG. 4 is a diagram showing a second example of the internal configuration of the ultrapure water supply apparatus shown in FIG. [Figure 2(C)] 1. FIG. 4 is a diagram showing a third example of the internal configuration of the ultrapure water supply apparatus shown in FIG. [Figure 3] 2 is a graph showing an example of a comparison of the concentrations of elements at the inlet and outlet of the ultrapure water supply system shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] 1 is a diagram showing an embodiment of an ultrapure water production system of the present invention. As shown in FIG. 1, the ultrapure water production system of this embodiment has a secondary pure water production apparatus 10 and an ultrapure water supply apparatus 20.

[0012] The secondary pure water production system 10 is a subsystem that produces secondary pure water (ultrapure water) from primary pure water produced in a primary pure water production system (not shown). In this embodiment, the secondary pure water production system 10 is equipped with a water treatment device that performs a predetermined impurity removal process on the primary pure water supplied from the primary pure water production system and the ultrapure water (circulating water, return water) that is not supplied to the ultrapure water supply system 20 but is circulated via a circulation pipe. The secondary pure water production system 10 may be equipped with multiple water treatment devices.

[0013] For example, as shown in FIG. 1, a secondary pure water production system 10 includes a primary pure water tank 11, a pump 12, an ultraviolet oxidation device 13, an ion exchange device 14, and an ultrafiltration (UF) membrane device 15. The secondary pure water production system 10 sequentially processes primary pure water produced in a primary pure water production system (not shown) to produce ultrapure water with anion and metal concentrations at ppt levels, and supplies the ultrapure water to an ultrapure water supply system 20. Ultrapure water with anion and metal concentrations at ppt levels refers to ultrapure water with anion and metal concentrations less than 10 ng / L (10 ppt). Here, ultrapure water with anion and metal concentrations at ppt levels refers to ultrapure water with at least one anion (particularly chloride ion) and at least one metal element (particularly sodium) concentrations less than 10 ng / L. Trace amounts of impurities may be eluted from the piping connecting the secondary pure water production system 10 to the user device 30. The elution of such trace amounts of impurities can have a significant impact on equipment that uses ultrapure water containing extremely low concentrations of impurities, such as anion and metal concentrations at the ppt level. For example, if the equipment 30 using the water is a semiconductor manufacturing equipment, the elution of trace amounts of impurities becomes a significant problem in semiconductor manufacturing. Note that the anion and metal concentrations of the ultrapure water produced by the secondary pure water production system 10 are preferably less than 5 ng / L (5 ppt).

[0014] The water to be treated (primary pure water) stored in the primary pure water tank 11 is pumped by a pump 12 and supplied to an ultraviolet oxidation device 13 where it is irradiated with ultraviolet light to decompose the total organic carbon (TOC) in the water. The water to be treated then undergoes ion exchange treatment in an ion exchange device 14 to remove ionic components such as metal ions. The water from which the ionic components have been removed undergoes particulate removal in a UF membrane device 15. A portion of the ultrapure water thus obtained is supplied to an ultrapure water supply device 20, and the remainder is returned to the primary pure water tank 11. Primary pure water is supplied to the primary pure water tank 11 from a primary pure water system (not shown) as needed. The piping from the ion exchange device 14 to the ultrapure water supply device 20 may be made of fluororesin piping, PVC piping with an emphasis on low elution properties, metal piping, or metal piping with a polyethylene powder lining. However, when metal piping or metal piping lined with a polyethylene powder is used, there is a risk of metal elution from the components that make up the piping. Furthermore, when fluororesin piping is used, metal elution from the components that make up the piping can be suppressed, but there is a problem that the manufacturing cost of the ultrapure water production system increases. Therefore, by using, for example, PVC piping or PP (polypropylene) piping for ultrapure water as the piping from the ion exchange device 14 to the ultrapure water supply device 20, it is possible to suppress metal elution from the components that make up the piping and keep the manufacturing cost of the ultrapure water production system low.

[0015] The ultrapure water supply system 20 reduces the concentration of impurities contained in the ultrapure water supplied from the secondary pure water production system 10 and supplies the ultrapure water to a use device 30 installed at a point of use where the ultrapure water is used. The closer the ultrapure water supply system 20 is located to the use device 30, the more preferable it is. As long as the quality of the treated water from the ultrapure water supply system 20 is higher than that of the water to be treated, the impurity removal performance of the ultrapure water supply system 20 is not particularly limited. For example, the ultrapure water supply system 20 has the function of removing trace amounts of impurities contained in the ultrapure water supplied from the secondary pure water production system 10 (e.g., impurities eluted from the piping between the secondary pure water production system 10 and the ultrapure water supply system 20), that is, reducing the concentration of impurities and improving the quality of the ultrapure water. The ultrapure water supply system 20 removes impurities from the ultrapure water supplied from the secondary pure water production system 10 as required according to the water quality required by the use device 30. The ultrapure water supply system 20 removes impurities from the ultrapure water supplied from the secondary pure water production system 10 and supplies the ultrapure water (hereinafter referred to as ultra-ultrapure water) to the user device 30. Examples of impurities that the ultrapure water supply system 20 removes from the ultrapure water include metals, organic matter including TOC (Total Organic Carbon), dissolved oxygen, hydrogen peroxide, and fine particles. The ultrapure water supply system 20 includes a water treatment device therein that performs a unit operation (e.g., removal of impurities) according to the water quality required by the user device 30. Examples of water treatment devices that may be included in the ultrapure water supply system 20 include an ion exchange device if the purpose is to remove metal ions, a UV oxidation device if the purpose is to remove organic matter including TOC, a degassing membrane device if the purpose is to remove dissolved oxygen, and a filtration membrane device including a microfiltration membrane or ultrafiltration membrane if the purpose is to remove fine particles. In this case, the ion exchange device provided in the ultrapure water supply system 20 has an ion exchanger such as an ion exchange resin, a monolithic ion exchanger, or an ion adsorption membrane.

[0016] The user device 30 is a device that uses ultra-pure water supplied from the ultrapure water supply device 20. The user device 30 may be a device that uses ultrapure water to clean components of semiconductor devices or liquid crystal displays. The user device 30 may also be a device that uses ultrapure water to clean medical products. The user device 30 may also be a device that uses ultrapure water in a steam generator of a power generation turbine.

[0017] Figure 2(A) is a diagram showing a first example of the internal configuration of the ultrapure water supply system 20 shown in Figure 1. As shown in Figure 2(A), the ultrapure water supply system 20 shown in Figure 1 is provided with an ion exchange device 21 having a monolithic ion exchanger, and a filtration membrane device 22 including a filter module filled with an ultrafiltration membrane (UF) or a microfiltration membrane (MF).

[0018] The ion exchange device 21 with a monolithic ion exchanger is equipped with a monolithic packed column made of a fluororesin such as PVDF (polyvinylidene fluoride) or PTFE (polytetrafluoroethylene) packed with a monolithic ion exchanger for deionizing ultrapure water. Examples of monolithic organic porous structures include the open-cell structure disclosed in JP 2002-306976 A and JP 2009-62512 A, the bicontinuous structure disclosed in JP 2009-67982 A, the particle aggregation structure disclosed in JP 2009-7550 A, and the particle composite structure disclosed in JP 2009-108294 A. The structure, materials, and properties of the ion exchanger are disclosed in JP 2019-195763 A. In addition, the ion exchange groups introduced into the monolithic organic porous column, the cation exchange groups introduced into the monolithic organic porous cation exchanger, and the anion exchange groups introduced into the monolithic organic porous anion exchanger are disclosed in JP 2019-195763 A. The monolithic packed column is washed and quality-controlled using ultrapure water or acid before being installed in the ion exchange device 21 having a monolithic ion exchanger. The quality control involves passing ultrapure water through the washed monolithic packed column, and a pre-installation inspection is performed based on the metal concentrations of the upstream and downstream ultrapure waters to be evaluated. The condition for installation in the ion exchange device 21 having a monolithic ion exchanger is that the elution concentration of metal ions (e.g., sodium) is below a predetermined threshold value in this pre-installation inspection.

[0019] The filter modules and / or the ultrafiltration membranes or microfiltration membranes (cartridges) to be filled are cleaned and quality-controlled using ultrapure water or acid before being installed in the filtration membrane device 22. Quality control is performed by passing ultrapure water through the cleaned filter modules or cartridges, and a pre-installation inspection is performed based on the metal concentrations of the upstream and downstream ultrapure waters to be evaluated. In this pre-installation inspection, the elution concentration of metal ions (e.g., sodium) must be below a predetermined threshold value to be incorporated into the filtration membrane device 22.

[0020] The piping from the ion exchange device 21 to the usage device 30 is made of fluororesin. An example of the fluororesin used here is PVDF. By using piping made of PVDF, the amount of metal elution from the inside of the piping from the ion exchange device 21 to the usage device 30 can be reduced. Furthermore, the closer the ultrapure water supply device 20 is located to the usage device 30, the less fluororesin can be used for the piping.

[0021] Figure 2(B) is a diagram showing a second example of the internal configuration of the ultrapure water supply system 20 shown in Figure 1. As shown in Figure 2(B), the ultrapure water supply system 20 shown in Figure 2 is provided with an ion exchange device 23 having a non-regenerated ion exchange resin, and a filtration membrane device 22. The filtration membrane device 22 is the same as that shown in Figure 2(A).

[0022] The ion exchanger 23, which has a non-regenerative ion exchange resin, is a packed column (ion exchanger) filled with granular ion exchange resin for deionizing ultrapure water. The ion exchanger is filled with a mixture of anion and cation resins. As shown in FIG. 1, the secondary pure water production system 10 is equipped with an ultraviolet oxidation device 13 to reduce organic matter in the water being treated. To remove carbonate ions generated by the decomposition of organic matter in the ultraviolet oxidation device 13 using the ion exchanger 14, the ion exchanger 14 is often filled with cation and anion exchange resins with the same exchange capacity or with anion exchange resins with a higher exchange capacity than the cation exchange resin. The water being treated and supplied to the ultrapure water supply system 20 has been treated in the secondary pure water production system 10 to reduce metal and anion concentrations to less than 5 ng / L (sodium concentrations are less than 10 pg / L as an effective value). Therefore, the load imposed on the anion exchange resin in the ion exchanger 23 by carbonate ions generated by the decomposition of organic matter is not as high as the load imposed on the resin in the ion exchanger 14 in the secondary pure water production system 10 (the TOC components eluted from the piping components downstream of the ion exchanger 14, the UF membrane device 15, etc., are actually 0.5 μg-C / L, while the inlet of the ultraviolet oxidation device 13 is 1 to 5 μg-C / L). From the perspective of metal removal, the ion exchanger in the ion exchanger 23 is filled with a mixture of cation exchange resins with a volume ratio of 1 to 1.0. Anionic organic matter may elute from the cation exchange resin. Anionic organic matter eluted from the cation exchange resin, such as polystyrene sulfonic acid, is adsorbed onto the anion exchange resin. Cationic organic matter may elute from the anion resin. Cationic organic matter eluted from the anion resin, such as trimethylamine, is adsorbed onto the cation exchange resin. In this way, since the eluate from the cation exchange resin is removed by the anion exchange resin, and the eluate from the anion exchange resin is removed by the cation exchange resin, it is important to mix the cation exchange resin and the anion exchange resin and fill the ion exchanger of the ion exchange device 23 with them.Furthermore, among metal species, some exist in the form of cations (e.g., sodium, potassium, etc.) and some exist in the form of anions (e.g., tungsten, arsenic, etc.). From the viewpoint of metal removal, it is desirable to mix a cation exchange resin and an anion exchange resin and fill the ion exchanger of the ion exchange device 23 with the mixture.

[0023] The piping from the ion exchange device 23 to the usage device 30 is made of fluororesin. An example of the fluororesin used here is PVDF. By using piping made of PVDF, the amount of metal elution from the inside of the piping from the ion exchange device 23 to the usage device 30 can be reduced. Furthermore, the closer the ultrapure water supply device 20 is located to the usage device 30, the less fluororesin can be used for the piping.

[0024] Figure 2(C) is a diagram showing a third example of the internal configuration of the ultrapure water supply system 20 shown in Figure 1. As shown in Figure 2(C), the ultrapure water supply system 20 shown in Figure 1 is provided with an ion exchange unit 24 and a filtration membrane device 22. The filtration membrane device 22 is the same as that shown in Figure 2(A).

[0025] The ion exchange unit 24 is an ion exchange device comprising an ion exchange device 21 with a monolithic ion exchanger or an ion exchange device 23 with a non-regenerative ion exchange resin, and an ion exchange device containing a platinum group metal-supported resin (e.g., a single bed of Pd catalyst-supported resin or a combination of an anion exchanger and a Pd catalyst-supported resin) connected in series with the ion exchange device 21 with a monolithic ion exchanger or the ion exchange device 23 with a non-regenerative ion exchange resin upstream of the ion exchange device 21 with a monolithic ion exchanger or the ion exchange device 23 with a non-regenerative ion exchange resin. The platinum group metal-supported resin is a platinum group metal supported on an anion exchange resin as a carrier and has the catalytic action of decomposing hydrogen peroxide into water and oxygen (2H2O2 → 2H2O + O2). Therefore, the ion exchange device provided in the ion exchange unit 24 can remove not only ionic components such as metal ions contained in the water to be treated but also hydrogen peroxide by contacting the water to be treated with the platinum group metal-supported resin. Palladium is preferably used as the platinum group metal for the platinum group metal-supported resin because of its excellent catalytic activity and relatively low cost.

[0026] The piping from the ion exchange unit 24 to the use device 30 is made of fluororesin. An example of the fluororesin used here is PVDF. By using piping made of PVDF, the amount of metal elution from the inside of the piping from the ion exchange unit 24 to the use device 30 can be reduced. Furthermore, the closer the ultrapure water supply device 20 is located to the use device 30, the less fluororesin can be used for the piping.

[0027] In addition to the components shown in Figures 2(A) to 2(C), the ultrapure water supply system 20 shown in Figure 1 may also be equipped with a water treatment device that performs unit operations (e.g., removal of impurities) according to the water quality required by the device 30 used, such as a UV oxidation device or a degassing membrane device.

[0028] Figure 3 is a graph showing an example of a comparison of the concentration of each element at the inlet and outlet of the ultrapure water supply system 20 shown in Figure 1. Note that the values ​​on the vertical axis shown in Figure 3 are values ​​written for convenience in order to explain the level of concentration, and are not actual measured values. As shown in Figure 3, for each element, the concentration at the outlet is generally lower than the concentration at the inlet.

[0029] In the present invention, instead of the configuration shown in Figure 1 in which one secondary pure water production system 10, one ultrapure water supply system 20, and one user device 30 are connected in series, multiple ultrapure water supply systems 20 and multiple user devices 30 may be connected in parallel to the secondary pure water production system 10. In other words, the ultrapure water produced by the secondary pure water production system 10 may be supplied to multiple user devices. For this purpose, an ultrapure water supply system is provided for each of the multiple user devices. By providing multiple ultrapure water supply systems with different specifications depending on the usage method and required specifications of the user devices, it is possible to supply ultra-ultrapure water that meets a variety of requirements.

[0030] As described above, in the present invention, when ultrapure water produced by the secondary pure water production system 10 is supplied to a user device 30 installed at a point of use, an ultrapure water supply system 20 equipped with an ion exchanger is provided between the secondary pure water production system 10 and the user device 30. A material other than fluororesin is used to construct the piping from the ion exchanger 14 installed in the secondary pure water production system 10 to the ultrapure water supply system 20. Fluororesin is also used to construct the piping from the ion exchanger installed in the ultrapure water supply system 20 to the user device 30. This allows the ultrapure water supply system 20 to remove impurities eluted from the piping from the ion exchanger installed in the secondary pure water production system 10 to the ultrapure water supply system 20, thereby reducing elution from the piping from the ion exchanger installed in the ultrapure water supply system 20 to the user device 30. This improves the quality of ultrapure water supplied to the point of use. Furthermore, by using fluororesin, which is difficult to obtain due to a shortage of raw materials, in the piping from the ion exchange unit in the ultrapure water supply system 20 located near the user equipment 30 to the user equipment 30, only a minimum amount of fluororesin is required. Furthermore, by keeping the anion and metal concentrations of the ultrapure water produced by the secondary pure water production system 10 at low concentrations, such as on the ppt (ng / L) level, ultra-ultrapure water of stable quality can be supplied to the user equipment 30. Furthermore, by supplying ultrapure water with low anion and metal concentrations to the ultrapure water supply system 20, no significant fluctuations in water quality are observed even when the flow rate of the supplied ultrapure water is increased, and the amount of resin filled in the ion exchange unit located in the ultrapure water supply system 20 can be reduced. [Explanation of symbols]

[0031] 10 Secondary pure water production equipment 11 Primary pure water tank 12 Pump 13. Ultraviolet oxidation equipment 14, 21, 23 Ion exchange device 15 UF membrane equipment 20 Ultrapure water supply equipment 22 Filtration membrane equipment 24 Ion Exchange Unit 30 Equipment used

Claims

1. a secondary pure water production device that processes primary pure water to produce ultrapure water; an ultrapure water supplying device that treats the ultrapure water supplied from the secondary pure water producing device and supplies the treated water to a device that uses the treated water; The anion concentration and metal concentration of the ultrapure water produced by the secondary pure water production apparatus are less than 10 ng / L; In the ultrapure water production system, the piping from the ion exchange device provided in the secondary pure water production device to the ultrapure water supply device is made of a material other than fluororesin.

2. 2. The ultrapure water producing system according to claim 1, In the ultrapure water production system, the piping from the ion exchange device provided in the ultrapure water supply device to the device using the ultrapure water is made of fluororesin.

3. 3. The ultrapure water producing system according to claim 2, The ion exchange device provided in the ultrapure water supply system has a granular or monolithic ion exchanger.

4. 4. The ultrapure water producing system according to claim 3, the ion exchange device provided in the ultrapure water supply system is filled with an anion exchange resin and a cation exchange resin; The ultrapure water production system is filled with a mixture of the cation exchange resin and the anion exchange resin in a volume ratio of 1 or more.

5. 3. The ultrapure water producing system according to claim 2, The ultrapure water supply device is an ultrapure water manufacturing system including a filtration membrane device provided downstream of the ion exchange device.

6. 6. The ultrapure water producing system according to claim 5, The filtration membrane device is an ultrapure water production system configured using a microfiltration membrane module or an ultrafiltration module.

7. An ultrapure water supply system having a function of reducing the concentration of impurities contained in ultrapure water supplied from an ion exchange device installed in a secondary pure water production system that treats primary pure water to produce ultrapure water with anion and metal concentrations of less than 10 ng / L via piping made of a material other than fluororesin.

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