Cleaning method for ultrapure water supply system

Abstract

A cleaning method for an ultrapure water supply system is a method for cleaning an ultrapure water supply system including a water supply part that supplies ultrapure water from an ultrapure water manufacturing device to a use point, and a return part that returns unused ultrapure water from the use point to the ultrapure water manufacturing device, the cleaning method being a method for cleaning at least part of a section from the water supply part to the return part. Said cleaning method is characterized by: installing a cleaning unit equipped with a water supply pump and a fine particle removal device through which water supplied from the water supply pump passes; connecting a forward supply pipe, for the water fed from the cleaning unit, to one end side of the section; using the return pipe to connect the other end side of the section and a water reception side of the cleaning unit; and cleaning the section by causing cleaning water to pass through the section.

Description

How to clean an ultrapure water supply system

[0001] The present invention relates to a method for cleaning an ultrapure water supply system that supplies ultrapure water produced in an ultrapure water production apparatus.

[0002] The point of use of ultrapure water in a semiconductor manufacturing factory or the like is connected to a subsystem of the ultrapure water production system by an ultrapure water supply pipe, and any remaining ultrapure water not used at this point of use is returned to a sub-tank at the upstream stage of the subsystem via an unused ultrapure water return pipe.

[0003] Conventionally, when ultrapure water production equipment and ultrapure water supply systems are newly installed, expanded, modified, or maintained, dust particles in the air, other fine particles, particles contained in water such as iron rust, and even shavings generated during the manufacturing process (hereinafter collectively referred to as "fine particles") are mixed into the system. These particles are removed by cleaning the ultrapure water production equipment and supply systems when they are started up.

[0004] Conventionally, in order to clean a subsystem and an ultrapure water supply system, after the subsystem and the ultrapure water supply system are completed, cleaning is performed with an alkali such as TMAH (tetramethylammonium hydroxide) or water containing hydrogen peroxide, or both (e.g., Patent Documents 1 and 2).

[0005] JP 2000-317413 A JP 2002-192162 A

[0006] In Patent Documents 1 and 2, chemical solutions are passed through the subsystems and point-of-use piping (piping for supplying ultrapure water and piping for returning unused ultrapure water) after the subsystems and point-of-use piping are constructed, and cleaning is not performed until the entire subsystem and point-of-use piping is completed, which means that it takes a long time from the start of system construction to the end of cleaning.

[0007] Furthermore, in an ultrapure water production and use facility (such as a semiconductor manufacturing plant) consisting of an existing ultrapure water production system, a use point, and piping for the use point, if a new line equipped with a wafer cleaner or the like is added to the use point, chemicals cannot be passed through the existing ultrapure water production system and line that are in operation. Therefore, the only method available for the new line is blow cleaning with ultrapure water, and it takes a long time to complete sufficient cleaning of the new line.

[0008] An object of one aspect of the present invention is to provide a method for cleaning only an ultrapure water supply system or only a part of the system in a facility that produces and uses ultrapure water.

[0009] The gist of the present invention is as follows.

[0010] [1] A method for cleaning an ultrapure water supply system having a water supply section that supplies ultrapure water from an ultrapure water production apparatus to a use point and a return section that returns unused ultrapure water from the use point to the ultrapure water production apparatus, the method cleaning at least a part of a compartment from the water supply section to the return section, comprising: installing a cleaning unit equipped with a water supply pump and a particle removal device through which the water from the water supply pump is passed; connecting a forward pipe for the water sent out from the cleaning unit to one end of the compartment; connecting the other end of the compartment to the water receiving side of the cleaning unit by a return pipe; and passing cleaning water through the compartment to clean the compartment.

[0011] [2] The method for cleaning an ultrapure water supply system according to [1], wherein the compartment is the whole or part of the water supply section, the use point, and the return section.

[0012] [3] The method for cleaning an ultrapure water supply system according to [1] or [2], wherein the compartment is cleaned during construction of the ultrapure water production system or before water starts flowing after construction.

[0013] [4] The method for cleaning an ultrapure water supply system according to [1], wherein the section is a line newly added to the point of use.

[0014] [5] The method for cleaning an ultrapure water supply system according to [4], wherein the line is cleaned while the ultrapure water production apparatus and use points other than the line are in operation.

[0015] [6] The cleaning method for an ultrapure water supply system according to any one of [1] to [5], wherein primary pure water is supplied as cleaning water to the cleaning unit.

[0016] [7] The cleaning method for an ultrapure water supply system according to any one of [1] to [5], wherein pure water from another system is supplied to the cleaning unit as cleaning water.

[0017] [8] The method for cleaning an ultrapure water supply system according to any one of [1] to [5], wherein the cleaning unit is installed before the start of cleaning and removed after the end of cleaning.

[0018] According to one aspect of the present invention, by installing a temporary cleaning unit, it is possible to clean the entire flow path from the ultrapure water supply section to the unused ultrapure water return section via the use point, or to clean only a portion of the flow path.

[0019] According to one aspect of the present invention, it is possible to clean only the portion from the water supply section to the use point to the water return section, for example, it is possible to clean only the piping for the use point.

[0020] According to one aspect of the present invention, it is possible to clean only a portion of the lines at a point of use. Therefore, when a new line is added to an existing point of use, it is possible to clean only the added line without stopping the operation of the existing subsystem or point of use.

[0021] Fig. 1 is a flow diagram of an ultrapure water supply system to which the method of the present invention is applied. Fig. 2 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. Fig. 3 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. Fig. 4 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. Fig. 5 is a configuration diagram of a temporary cleaning unit. Fig. 6 is a configuration diagram of a temporary cleaning unit.

[0022] Hereinafter, an embodiment will be described with reference to the drawings.

[0023] FIG. 1 is a flow diagram of an ultrapure water supply system to which the method of the present invention is applied.

[0024] Primary pure water from a primary pure water system (not shown) is introduced into a sub-tank 2 via a primary pure water pipe 1. The water in the sub-tank 2 is treated by a subsystem (secondary pure water system) 3 to produce ultrapure water. This ultrapure water is delivered to a point of use 5 via an ultrapure water delivery pipe 4.

[0025] The point of use 5 has a plurality of lines (five in this embodiment) 5a, 5b, 5c, 5d, and 5e arranged in parallel. Each line is equipped with a wafer cleaner or the like, and wafers and the like are cleaned with ultrapure water. The wafer cleaning wastewater is discharged outside the system via a drainage pipe (not shown). Unused ultrapure water that was not used to clean wafers and the like is returned to the subtank 2 via a return pipe 6.

[0026] The primary pure water production system is equipped with a reverse osmosis (RO) membrane separation device, a degassing device, a regenerative ion exchange device (mixed-bed type or 4-bed 5-tower type, etc.), an electric deionization device, an oxidation device such as an ultraviolet (UV) irradiation oxidation device, etc., and is used to remove most of the electrolytes, fine particles, live bacteria, etc. from the pretreated water.

[0027] Subsystem 3 is composed of a water supply pump, a cooling heat exchanger, a low-pressure ultraviolet oxidation device, a non-regenerative mixed-bed ion exchange device, and a membrane filtration device such as an ultrafiltration (UF) membrane separation device, and may also be equipped with a membrane degasser, an RO membrane separation device, an electrodeionization device, etc.

[0028] In the low-pressure ultraviolet oxidation equipment, the 185 nm ultraviolet light emitted from the low-pressure ultraviolet lamp is used to convert TOC into organic acids and further CO ２ The organic matter and CO produced by the decomposition ２ The fine particles are removed in the downstream ion exchange unit and degassing unit. In the UF (ultrafiltration) unit, the fine particles are removed, and the particles effluent from the ion exchange resin are also removed, resulting in ultrapure water.

[0029] In one aspect of the present invention, before the construction of subsystem 3 is completed or before the start of operation after completion, as shown in Fig. 2, a cleaning unit 10 is temporarily installed and pipes 7, 8, and 9 are connected to pipes 1, 4, and 6. Then, pipe 4, each of lines 5a to 5e at the use points, and pipe 6 are cleaned.

[0030] This cleaning unit 10 is equipped with a filter and a water supply pump. Primary pure water received in this cleaning unit 10 via pipe 7 is supplied via pipe 8 (outgoing pipe) to a portion of pipe 4 closest to subsystem 3, and flows through pipe 4, point of use 5, and pipe 6. Then, cleaning water returning from pipe 6 via pipe 9 (return pipe) is received into cleaning unit 10, filtered by a filter within cleaning unit 10, and then sent again from pipe 8 to pipe 4. In this way, pipe 4, each line 5a to 5e of the point of use, and pipe 6 are circulated and cleaned. After cleaning is completed, the cleaning wastewater is discharged through pipe 11.

[0031] As shown in FIG. 2, a valve 7v is provided in the pipe 7, and the valve 7v is opened when primary pure water is received in the cleaning unit 10, and is closed at other times.

[0032] In Figure 2, a valve (not shown) is provided in the pipe 6 at the portion closest to the sub-tank 2 (the sub-tank 2 side of the branching point of the pipe 9), and this valve is closed when cleaning is performed by the cleaning unit 10 and is open at other times.

[0033] In Figure 2, a valve (not shown) is provided in the pipe 4 closest to the subsystem 3 (on the subsystem 3 side relative to the junction with the pipe 8), and this valve is closed during cleaning by the cleaning unit 10 and is open at other times.

[0034] After the above cleaning is completed, the cleaning unit 10 and the pipes 7, 8, and 9 are removed.

[0035] As the cleaning unit 10, a cleaning unit 10A shown in FIG. 6 or a cleaning unit 10B shown in FIG. 7 is suitable.

[0036] 6, the cleaning unit 10A receives primary pure water via a pipe 7, passes it through a particulate removal device 15 serving as a filter via a pipe 12, a pump 13, and a pipe 14, and supplies the filtered water that has passed through the particulate removal device 15 to the water supply pipe 4 via a pipe 8. In addition, the cleaning unit 10A is configured to receive return cleaning water from the pipe 6 via a pipe 9 and circulate it in the pipe 12.

[0037] A drain pipe 11 for draining washing wastewater branches off from the pipe 12, and a valve 11v is provided on this pipe 11. This valve 11v is opened when draining water after washing is completed, and is closed at other times.

[0038] 7 is the same as the cleaning unit 10A in Fig. 6 except that a tank 18 is installed, the primary pure water from the pipe 7 and the return water from the pipe 9 are received in the tank 18, and the water in the tank 18 is sent to the particle removal device 15 by a pump 13. The pipe 11 is connected to the tank 18.

[0039] A cleaning chemical such as an alkali, an acid, or hydrogen peroxide may be added to this tank 18. When a chemical is added, after the chemical cleaning is completed, the valve 11v is opened and the cleaning waste liquid is discharged, and then primary pure water is introduced through the pipe 7, and the pipe 4, the use point 5, and the pipe 6 are rinsed with the primary pure water.

[0040] In FIG. 2, primary pure water is introduced into the cleaning unit 10 through the pipe 1. However, as shown in FIG. 3, the receiving side of the pipe 7 may be connected to a primary pure water device or subsystem of a different series, and pure water (primary pure water or ultrapure water) from the different series may be introduced into the cleaning unit 10.

[0041] Other configurations in FIG. 3 are the same as those in FIG. 2, and the same reference numerals denote the same parts.

[0042] 2 and 3, the cleaning unit 10 is configured to circulate and clean the pipe 4, the use point 5, and the pipe 6, but as shown in Figures 4 and 5, it is also possible to clean only the line 5f newly added to the use point 5. The line 5f is installed in parallel with the lines 5a to 5e.

[0043] 4 and 5, the outlet of pipe 8 is connected to the vicinity of the inlet of line 5f, and the inlet of pipe 9 is connected to the vicinity of the outlet of line 5f. Other configurations in Fig. 4 are the same as those in Fig. 2, and other configurations in Fig. 5 are the same as those in Fig. 3, and the same reference numerals denote the same parts.

[0044] In Figures 4 and 5, cleaning water from the cleaning unit 10 is supplied to one end of the line 5f via the pipe 8, and the cleaning wastewater (return cleaning water) flowing out from the other end of the line 5f returns to the cleaning unit 10 via the pipe 9, so that only the line 5f is cleaned.

[0045] 4 and 5, when a new line is added in parallel to a use point in an existing ultrapure water production and use system, the existing equipment (subsystem 3 and each of lines 5a to 5e) can be left in operation, and only the newly added line 5f can be cleaned. In this way, by using a temporary cleaning unit, it is possible to blow and clean the ultrapure water supply pipe to be cleaned, regardless of the operating / usage status of the subsystem and surrounding ultrapure water supply pipe.

[0046] In the above embodiment, only the pipe 4, the use point 5, and the pipe 6 are cleaned, or only the line 5f is cleaned, but other sections may also be cleaned. Also, the area to be cleaned may be divided into multiple sections, and each section may be cleaned in turn. Furthermore, multiple cleaning units may be used to clean two or more sections simultaneously.

[0047] The washing unit 10 has a water supply capacity of 0.5 to 200 m ３ / h, and it is preferable to use a unit that can deliver the amount of water required depending on the size of the pipe to be cleaned.

[0048] The amount of water sent from the washing unit 10 is, for example, 10 m ３ / h or more, a UF membrane module for ultrapure water production equipment (treatment water volume 15 m ３ When cleaning the entire ultrapure water supply piping connected to the ultrapure water production equipment, the standard for the amount of water sent by the cleaning unit is usually 10 m ３ / h~100m３ In this case, the main amount of treated water in an ultrapure water production facility is 10 m ３ / h~50m ３ For cleaning ultrapure water supply piping connected to a subsystem on a per hour scale, 1 to 5 UF membrane modules are required, or the treated water volume of a relatively large ultrapure water production facility is 50 m ３ / h~100m ３ For cleaning the ultrapure water supply pipes connected to a subsystem on a per hour scale, it is preferable to use a particle removal device 15 that has about 5 to 10 UF membrane modules.

[0049] 100m seen in large-scale ultrapure water production facilities ３ / h~200m ３ For cleaning of ultrapure water supply piping connected to a subsystem on a per hour scale, it is preferable to use a particle removal device with about 10 to 20 UF membrane modules. ３ / h, a membrane cartridge filter (with a treatment capacity of 2 m3) is used as a particulate removal device. ３ When only a portion of the ultrapure water supply pipe is to be cleaned, or when the entire ultrapure water supply pipe is to be cleaned in separate sections, a cleaning unit with a water volume less than the above-mentioned standard amount may be used.

[0050] The above-described embodiment is an example of the present invention, and the present invention may be embodied in other forms.

[0051] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the effects of the invention. This application is based on Japanese Patent Application No. 2024-130030 filed on August 6, 2024, and is incorporated by reference in its entirety.

[0052] 2 Sub-tank 3 Subsystem 5 Use point 5a to 5f Lines 10 (10A, 10B) Cleaning unit 15 Particle removal device

Claims

1. A method for cleaning an ultrapure water supply system having a water supply section that supplies ultrapure water from an ultrapure water production system to a use point and a return section that returns unused ultrapure water from the use point to the ultrapure water production system, a method for cleaning at least a portion of a compartment from the water supply section to the return section, comprising: installing a cleaning unit equipped with a water supply pump and a particle removal device through which water from the water supply pump is passed; connecting a forward pipe for water sent from the cleaning unit to one end of the compartment; connecting the other end of the compartment to the water receiving side of the cleaning unit with a return pipe; and passing cleaning water through the compartment to clean the compartment.

2. The method for cleaning an ultrapure water supply system according to claim 1, wherein the compartment is the whole or a part of the water supply section, the use point and the return section.

3. The method for cleaning an ultrapure water supply system according to claim 1, wherein the compartment is cleaned during construction of the ultrapure water production system or before water starts flowing after construction.

4. The method for cleaning an ultrapure water supply system according to claim 1, wherein the section is a line newly added to the point of use.

5. The method for cleaning an ultrapure water supply system according to claim 4, wherein the line is cleaned while the ultrapure water production apparatus and use points other than the line are in operation.

6. A method for cleaning an ultrapure water supply system according to any one of claims 1 to 5, wherein primary pure water is supplied as cleaning water to said cleaning unit.

7. A method for cleaning an ultrapure water supply system according to any one of claims 1 to 5, wherein pure water from another line is supplied to said cleaning unit as cleaning water.

8. The method for cleaning an ultrapure water supply system according to any one of claims 1 to 5, wherein the cleaning unit is installed before the start of cleaning and removed after the end of cleaning.

Images