How to clean an ultrapure water supply system

Abstract

A method for cleaning only an ultrapure water supply system in a facility that produces and uses ultrapure water is provided. [Solution] 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, which cleans at least a portion of the compartment from the water supply section to the return section, comprises 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 pipe for sending water from the cleaning unit to one end of the compartment, and 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.

Description

[Technical Field]

[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. [Background technology]

[0002] The point of use (use point) of ultrapure water in a semiconductor manufacturing factory or the like is connected to a subsystem of the ultrapure water production equipment by an ultrapure water supply pipe, and the remaining ultrapure water that is not used at this use point is returned to a sub-tank in 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 installed, expanded, modified, or maintained, dust and other fine particles in the air, 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, to clean a subsystem and an ultrapure water supply system, after the subsystem and the ultrapure water supply system are completed, they are cleaned with an alkali such as TMAH (tetramethylammonium hydroxide) or water containing hydrogen peroxide, or both (e.g., Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-317413 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-192162 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Documents 1 and 2, chemical solutions are passed through the subsystems and use point piping (ultrapure water supply piping and unused ultrapure water return piping) after the subsystems and use point piping are constructed, and cleaning is not performed until the entire subsystem and use point 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, use point, and use point piping, 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 that can be used 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. [Means for solving the problem]

[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 system to a use point and a return section that returns unused ultrapure water from the use point to the ultrapure water production system, comprising: A method for cleaning at least a portion of a section from the water supply section to the return section, comprising: a cleaning unit including a water pump and a particulate removal device through which water is passed from the water pump; a pipe for sending water sent from the cleaning unit is connected to one end of the compartment, and a pipe for returning water is connected to the other end of the compartment and the water receiving side of the cleaning unit; A method for cleaning an ultrapure water supply system, comprising 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] A method for cleaning an ultrapure water supply system according to [1] or [2], in which 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 the ultrapure water supply system of [1], wherein the section is a line newly added to the use point.

[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. [Effects of the Invention]

[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 point of use to the water return section, for example, it is possible to clean only the piping for the point of use.

[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. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a flow diagram of an ultrapure water supply system to which the method of the present invention is applied. [Figure 2] 1 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. [Figure 3] 1 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. [Figure 4] 1 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. [Figure 5] 1 is a flow diagram of an ultrapure water supply system to which the cleaning method of the present invention is applied. [Figure 6] FIG. 2 is a diagram illustrating the configuration of a temporary cleaning unit. [Figure 7] FIG. 2 is a diagram illustrating the configuration of a temporary cleaning unit. DETAILED DESCRIPTION OF THE INVENTION

[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 use point 5 via an ultrapure water delivery pipe 4.

[0025] The point of use 5 has multiple (five in this embodiment) lines 5a, 5b, 5c, 5d, and 5e installed 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 ultraviolet (UV) irradiation oxidation device or other oxidation device, and is used to remove most of the electrolytes, fine particles, live bacteria, etc. from the pre-treated 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, but may also be equipped with a membrane degasser, an RO membrane separation device, an electrodeionization device, etc.

[0028] In the low-pressure ultraviolet oxidation unit, 185 nm ultraviolet light emitted from a low-pressure ultraviolet lamp is used to decompose TOC into organic acids and even CO2. The organic matter and CO2 produced by the decomposition are removed in the downstream ion exchange unit and degassing unit. In the UF (ultrafiltration) unit, fine particles are removed, as well as particles effluent from the ion exchange resin, to produce 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 5, lines 5a to 5e, 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 returned 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 5, lines 5a to 5e, and pipe 6 are circulated and cleaned. After cleaning is completed, the waste cleaning water is discharged through pipe 11.

[0031] After the cleaning is completed, the cleaning unit 10 and the pipes 7, 8, and 9 are removed.

[0032] As the cleaning unit 10, a cleaning unit 10A shown in FIG. 6 or a cleaning unit 10B shown in FIG. 7 is used.

[0033] The cleaning unit 10A receives primary pure water through a pipe 7, passes it through a particulate remover 15 serving as a filter, and passes it through a pipe 12, a pump 13, and a pipe 14, and supplies the filtered water that has passed through the particulate remover 15 to the water supply pipe 4 through a pipe 8. In addition, the cleaning unit 10A is configured to receive return cleaning water from the pipe 6 through a pipe 9 and circulate it in the pipe 12.

[0034] A pipe 11 for discharging 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.

[0035] 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 into the cleaning unit 10, and is closed at other times.

[0036] Although not shown in the figure, a valve is provided in the part of the piping 6 closest to the sub-tank 2 (on the sub-tank 2 side rather than the branching point of the piping 9), and this valve is closed when cleaning is performed by the cleaning unit 10, and is open at other times.

[0037] Similarly, a valve (not shown) is provided in the portion of piping 4 closest to subsystem 3 (on the subsystem 3 side relative to the junction with piping 8), and this valve is closed when cleaning is performed by cleaning unit 10 and is open at other times.

[0038] 7 is a cleaning unit 10B in which a tank 18 is installed in the cleaning unit 10A in FIG. 6, and 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 particulate removal device 15 by a pump 13. The pipe 11 is connected to this tank 18.

[0039] Cleaning chemicals such as alkali, acid, or hydrogen peroxide may be added to this tank 18. If chemicals are added, after the chemical cleaning is completed, valve 11v is opened and the cleaning waste liquid is discharged, and then primary pure water is introduced through pipe 7, and pipe 4, use point 5, and 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, but 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] The 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 FIGS. 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 near the inlet of line 5f, and the inlet of pipe 9 is connected near the outlet of line 5f. The other configurations in Fig. 4 are the same as those in Fig. 2, and the 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 line 5f via piping 8, and the cleaning wastewater (return cleaning water) flowing out from the other end of line 5f returns to the cleaning unit 10 via piping 9, so only 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, the ultrapure water supply pipe to be cleaned can be blown and cleaned without being affected by the operating / usage status of the subsystems and surrounding ultrapure water supply pipes.

[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. Also, multiple cleaning units may be used to clean two or more sections simultaneously.

[0047] The cleaning 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 cleaning unit 10 is, for example, 10 m 3 / h or more, a UF membrane module for ultrapure water production equipment (treatment water volume: up to 15m3) is used as a particulate removal device. 3When 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~100m 3 In this case, the main amount of treated water in an ultrapure water production facility is 10 m 3 / h~50m 3 For cleaning of ultrapure water supply piping connected to a subsystem on a / h scale, 1 to 5 UF membrane modules or 50 m3, which is the treated water volume of a relatively large ultrapure water production facility, are used. 3 / h~100m 3 For cleaning of ultrapure water supply piping connected to a subsystem on a / h scale, it is preferable to use a particulate 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 UF membrane module with 10 to 20 units as a particulate removal device. 3 / h, a membrane cartridge filter (treatment capacity 2 m3) is used as a particulate removal device. 3 It is preferable to use a combination of the required number of units (approximately / h or less). When cleaning only a portion of the ultrapure water supply piping, or when cleaning the entire ultrapure water supply piping in separate sections, a cleaning unit with a water volume less than the above-mentioned guideline 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. [Explanation of symbols]

[0051] 2 Subtank 3 Subsystems 5 Use Points 5a~5f line 10(10A, 10B) Cleaning unit 15 Particulate removal device

Claims

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

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

3. 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 to flow after construction.

4. 2. 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. 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. 6. The method for cleaning an ultrapure water supply system according to claim 1, wherein primary pure water is supplied as cleaning water to said cleaning unit.

7. 6. The method for cleaning an ultrapure water supply system according to claim 1, wherein pure water from another line is supplied to said cleaning unit as cleaning water.

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

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