JP2011072924A - Method for mounting constituent member of ultrapure water production system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mounting the constituent member of an ultrapure water production system including an ion exchange apparatus and a membrane separation apparatus arranged downstream therefrom by which, when members such as pumps, heat exchangers, valves and instruments composing a water passing part upstream from the ion exchange apparatus, contamination in the system caused by the mounted member and deterioration in the water quality of the ultrapure water due to the contamination are prevented, and ultrapure water with high purity satisfying the water quality requirement can be stably produced. <P>SOLUTION: The method for mounting the constituent member of an ultrapure water production system includes the member which is precleaned, then is mounted to the ultrapure water production system so that the number of fine particles in ultrapure water passed to the member becomes a prescribed value or below, upon passing of ultrapure water to the member to be mounted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for attaching components of an ultrapure water production system, and more particularly, an upstream side of an ion exchange device of an ultrapure water production system including an ion exchange device and a membrane separation device arranged downstream thereof. When replacing, repairing, adjusting, etc., the members that make up the water flow section, such as pumps, heat exchangers, valves, meters, etc., these members are temporarily removed from the ultrapure water production system, and again When attaching to a water production system, prevent contamination of the system by the attached components and the resulting deterioration in the quality of ultrapure water, so that high purity ultrapure water that meets the required water quality can be stably produced. The present invention relates to a method for attaching components of an ultrapure water production system.

  For the production of ultrapure water used in the production process of semiconductor products such as wafers, LSIs, liquid crystals, etc., ultrapure water that treats treated water (primary pure water) by ultraviolet irradiation, ion exchange, membrane separation, deaeration, etc. A manufacturing system is used. FIG. 1 shows an example of a conventional ultrapure water production system. This ultrapure water production system includes a storage tank 1, a liquid feed pump 2, a heat exchanger 3, an ultraviolet oxidizer 5, an ion exchange. An ultrapure water production unit 4 including an apparatus 6 and a UF (ultrafiltration) membrane separation apparatus 7 is provided. 8 is an ultrapure water feed pump, and 9 is a use point.

  In this ultrapure water production system, primary pure water (treated water) obtained in advance by treatment such as ion exchange is temporarily stored in the storage tank 1 together with return water from the use point 9, and then the liquid feed pump 2. Then, it is introduced into the pure water production unit 4 through the heat exchanger 3. In the pure water production unit 4, the water to be treated is irradiated with ultraviolet rays by the ultraviolet oxidizer 5, desalted by the ion exchanger 6, and filtered by the UF membrane separator 7 to obtain ultrapure water. The produced ultrapure water is supplied to the use point 9 by the liquid feed pump 8. The remaining ultrapure water that has not been used at the use point 9 is returned to the tank 1 as return water, and is circulated together with the primary pure water.

  The ultrapure water used in the manufacturing process of such semiconductor products is required to be free of fine particles, organic substances and inorganic substances that cause cleaning trouble. For example, resistivity: 18.2 MΩ · cm or more, number of fine particles: 1 / mL or less, viable count: 1 / L or less, TOC (Total Organic Carbon): 1 μg / L or less, silica: 1 μg / L or less, metals: 1 ng / L or less, ions: 10 ng / L or less The water quality is required.

  For this reason, in order to produce ultrapure water that satisfies such required water quality, various studies have been made on the production conditions and a cleaning method in an ultrapure water production system that produces ultrapure water.

  Conventionally, in the cleaning method of the ultrapure water production system, after the ultrapure water production system is completed by incorporating each component constituting the ultrapure water production system, only the location where the member is incorporated or the entire system Washing with pure water or, if necessary, ultrapure water containing TMAH (tetramethylammonium hydroxide) or hydrogen peroxide is performed (for example, Patent Document 1).

  In addition, in ion exchangers and UF membrane separators used in ultrapure water production units, substances that elute from them have a great influence on the purity of ultrapure water. Built into the ultrapure water production system.

  However, components such as pumps, heat exchangers, valves, and instruments are generally used on the upstream side of ion exchange devices and UF membrane separation devices, and contaminants flowing out from these members are ion exchange devices and UF membranes. Since it is removed by the separator, unless it is contaminated with oil that is difficult to remove dirt, it is not specially cleaned before being incorporated into the ultrapure water production system. After being assembled, the other members are cleaned together.

However, under the recent increase in the required water quality level for ultrapure water, the above-described conventional cleaning method has become unable to adequately cope with it.
As a result of studying this cause, the present inventors have confirmed that the ultrapure water production system does not have sufficient clarification even if it is a component member incorporated upstream of the ion exchange device and the UF membrane separation device. When incorporated and passed, dirt is discharged from these components at the initial stage of passing water, and the discharged dirt passes through a subsequent ion exchange device or UF membrane separation device, and the passed dirt passes through the UF. It has been found that water quality deteriorates due to adhering to the piping from the membrane separation device to the use point, etc., and mixing into ultrapure water produced by dissolving it gradually with time.

  In order to prevent metal contamination caused by the pump, the liquid contact part of the pump is made of a synthetic resin material (Patent Document 2), and an ion exchange filter is installed at the rear stage of the pump (Patent Document 3). Proposed. However, these prevent contamination of ultrapure water caused by the elution or separation of metal ions and fine metal particles little by little from the wetted parts of pumps and other parts already built into the ultrapure water production system. However, it does not prevent deterioration of the quality of the ultrapure water due to the dirt components that are attached to the incorporated member and brought into the ultrapure water production system.

JP 2000-317413 A Japanese Patent No. 3956671 JP 2000-10849 A

  The present invention has been made in view of the above-described conventional situation, and the upstream side of the ion exchange device of the ultrapure water production system including the ion exchange device and the membrane separation device arranged on the downstream side thereof is provided. When installing pumps, heat exchangers, valves, and instruments that make up the water section to the ultrapure water production system, prevent contamination of the system by the installed members and the resulting deterioration in the quality of ultrapure water. Another object of the present invention is to provide a method for attaching components of an ultrapure water production system for stably producing high purity ultrapure water that satisfies the required water quality.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have conventionally found constituent members on the upstream side of an ion exchange apparatus and a membrane separation apparatus that are attached to an ultrapure water production system without performing special cleaning. The present inventors have found that contamination in the system due to dirt brought in by an attached member can be prevented by attaching to an ultrapure water production system after pre-cleaning with ultrapure water to a predetermined cleanliness.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] In an ultrapure water production system including at least an ion exchange device and a membrane separation device arranged on the downstream side thereof, a member constituting a water flow portion upstream of the ion exchange device is used as the ultrapure water. A method of attaching to a manufacturing system, wherein the member is previously set so that the number of fine particles in the ultrapure water passed through the member when the ultrapure water is passed through the member is equal to or less than a predetermined value. A method for attaching components of an ultrapure water production system, comprising: attaching to the ultrapure water production system after cleaning.

[2] A method for attaching components of an ultrapure water production system according to [1], wherein the fine particles are fine particles having a particle diameter of 0.05 μm or more.

[3] In [1] or [2], after the member is washed in advance so that the number of fine particles in the ultrapure water passed through the member is 10,000 / mL or less, the ultrapure water production system is used. A method for attaching a component of an ultrapure water production system, wherein the component is attached.

[4] Ultrapure water according to any one of [1] to [3], wherein the member is one or more selected from the group consisting of a pump, a heat exchanger, a valve, and a meter. A method for attaching components of the manufacturing system.

According to the method for attaching the constituent members of the ultrapure water production system of the present invention, the upstream side of the ion exchange device of the ultrapure water production system comprising the ion exchange device and the membrane separation device arranged downstream thereof. When installing members such as pumps, heat exchangers, valves, instruments, etc. that constitute the water flow section, the members attached by washing the members with ultrapure water to a predetermined cleanliness beforehand. It is possible to stably produce high-purity ultrapure water that satisfies the required water quality by preventing contamination of the system and deterioration of the quality of ultrapure water.
In addition, in this way, it becomes possible to stably supply high-purity ultrapure water that satisfies the required water quality to the semiconductor manufacturing process, thereby preventing product deficiencies due to deterioration of the quality of ultrapure water in the semiconductor manufacturing process. Thus, the product yield can be kept high.

It is a systematic diagram which shows the structure of a general ultrapure water manufacturing system. 3 is a graph showing the change over time of the quality of ultrapure water produced in Test Example 1. FIG.

  Hereinafter, an embodiment of a method for attaching components of the ultrapure water production system of the present invention will be described in detail.

  The method of attaching the constituent members of the ultrapure water production system of the present invention is an ultrapure water production system comprising at least an ion exchange device and a membrane separation device arranged on the downstream side thereof, and more upstream than the ion exchange device. The number of fine particles in the ultrapure water that are passed through the member when the ultrapure water is passed through the member. Is attached to the ultrapure water production system after the member has been washed in advance so that is less than or equal to a predetermined value.

  The ultrapure water production system to which the present invention is applied is not particularly limited as long as it has an ion exchange device and a membrane separation device on the downstream side. As a general ultrapure water production system, the one shown in FIG. 1 can be cited. As the ion exchange device 6, a multi-bed type ion exchange device, a mixed bed type ion exchange device, a non-regenerative ion exchange device can be used. In addition to the UF membrane separation device 7, a microfiltration membrane separation device, a reverse osmosis membrane separation device, or a combination of these can be used as the membrane separation device. The pure water production unit 4 may further include a deaeration device (vacuum deaeration tower, membrane deaerator, nitrogen deaeration tower, decarbonation tower).

  In such an ultrapure water production system, the member constituting the water flow section upstream of the ion exchange device to be attached in the present invention is a member that comes into contact with water supplied to the ion exchange device. Although there is no particular limitation, for example, the pump 2 and its constituent members in FIG. 1, the heat exchanger 3 and its constituent members, and other valves and instruments (not shown) may be mentioned. Among these, the effect by applying the present invention is effectively exhibited especially for a pump having a complicated structure and difficult to clean.

  The present invention can be applied to the case where these members are newly installed in the ultrapure water production system. In particular, these existing members are used for maintenance such as replacement, repair, maintenance, inspection or adjustment. Ultrapure water produced in the ultrapure water production system and the produced ultrapure water by removing dirt components adhering to the member during the maintenance period when it is once removed from the pure water production system and reattached. It is effective in preventing pollution.

  In the present invention, prior to attaching these members to the ultrapure water production system, ultrapure water was passed through this member, and ultrapure water that was passed through (hereinafter, after being passed through the member to be cleaned, The ultrapure water flowing out from this member is sometimes referred to as “washing effluent.”) This member is cleaned in advance so that the fine particles in the member are below a predetermined value.

  Here, the quality of the ultrapure water used for cleaning the member is preferably the same as that of the ultrapure water produced by the ultrapure water production system to which the member is attached, and for example, the following water quality It is preferable.

<Ultrapure water quality>
Number of fine particles (0.05 μm or more): 100 / mL or less TOC: 5 μg / L or less Metal ion: 10 ng / L or less

  In the present invention, the attachment member is washed with such ultrapure water having a water quality, and the number of fine particles having a particle size of 0.05 μm or more in the washing effluent is preferably 10,000 / mL or less, for example, 1000 to 5000. After washing to about pcs / mL, attach to the ultrapure water production system. If the number of fine particles in the washing effluent is greater than this value, the cleanliness of the member will be insufficient. Therefore, after the member is attached to the ultrapure water production system, the quality of the produced ultrapure water is not stable. However, excessive cleaning of this member is not preferable because of high cost for cleaning. Accordingly, the cleaning is terminated when the cleaning effluent having the number of fine particles in the above range is obtained. More preferably, after washing so that the TOC concentration of the washing effluent is 10 μg / L or less, for example, 5 to 2 μg / L, and the metal ion concentration is 10 ng / L or less, for example, 0.1 to 3 ng / L. Install in the ultrapure water production system.

This cleaning is performed by passing ultrapure water through the member, evaluating the quality of the washing effluent, and repeating or continuing the passage of ultrapure water until the quality of the washing effluent reaches a predetermined value. be able to.
In this case, when cleaning a member that allows water to flow by itself, such as a pump or a heat exchanger, ultrapure water may be passed by this member alone for cleaning. Moreover, what is difficult to wash with water only by itself, such as components of valves and instruments or pumps and heat exchangers, may be washed with water while attached to a pump or heat exchanger, for example.

  In addition, in this water cleaning, not only ultrapure water, but also ultrapure water may be cleaned with chemicals usually used for in-system cleaning of ultrapure water production systems such as TMAH and hydrogen peroxide. In this case, after chemical cleaning, rinse (finish) cleaning with ultrapure water is performed to evaluate the quality of the cleaning effluent.

  The quality of the washed effluent water, that is, the number of fine particles, the TOC concentration, and the metal ion concentration can be measured and evaluated by the methods described in the Examples section below.

  In this way, prior to installation in the ultrapure water production system, after washing with ultrapure water until the quality of the washed effluent water is better than a predetermined level, the member is produced in ultrapure water. Attach to the system. After the member is attached to the ultrapure water production system, the production of the ultrapure water is resumed after cleaning the ultrapure water production system according to a conventional method.

As described above, conventionally, the water passage member upstream of the ion exchange device of the ultrapure water production system has not been attached to the ultrapure water production system after it has been previously cleaned to a predetermined cleanliness. It was.
According to the present invention, when such a member is attached to the ultrapure water production system, a value that serves as a reference for cleaning is indicated, so that excessive and insufficient cleaning of the member is prevented, and the cleaning operation with the minimum reduction is required. It becomes possible to maintain the quality of the ultrapure water produced by the ultrapure water production system high.

Hereinafter, the present invention will be described more specifically with reference to test examples and examples.
In the following, the quality of the ultrapure water produced by the ultrapure water production system is determined by measuring the number of fine particles of 0.05 μm or more in ultrapure water using a fine particle measuring instrument (particle counter KS17B manufactured by Rion Corporation). This was done by measuring.

[Test Example 1]
In the ultrapure water production system having the configuration shown in FIG. 1, for the maintenance of the pump 2, the production of ultrapure water is stopped, the pump 2 is removed, the necessary maintenance inspection is performed, and then the ultrapure water production system is used as it is. I put it back.
Thereafter, the production of ultrapure water was resumed, the change in the quality of the produced ultrapure water over time was examined, and the results are shown in FIG.

  As shown in FIG. 2, in Test Example 1, the number of fine particles of 0.05 μm or more at the outlet of the UF membrane separation device 7 is 1 hour after the restart of operation, and the fine particles of 0.05 μm or more at the pump outlet. Was less than 10,000 / mL, and stably became 1 / mL or less.

[Example 1]
In Test Example 1, after maintenance and inspection of the pump 2, before attaching to the ultrapure water production system again, the ultrapure water of the following water quality is passed through the pump for cleaning, and the cleaning effluent of the pump satisfies the following water quality. Until washed.

<Washing effluent>
Number of fine particles: 1000 to 5000 / mL

  The number of fine particles was examined by counting fine particles having a particle size of 0.05 μm or more in the washing effluent with the fine particle measuring instrument used in Test Example 1.

  As a result, the production of ultrapure water was resumed, and the number of fine particles at the outlet of the UF membrane separation device 7 after 1 hour was stable at 1 / mL or less.

  From these results, according to the present invention, it is possible to prevent deterioration of the quality of ultrapure water due to dirt components brought in at the time of installation of components on the upstream side of the ion exchange apparatus and the membrane separation apparatus, It turns out that a pure water can be manufactured stably.

DESCRIPTION OF SYMBOLS 1 Tank 2 Pump 3 Heat exchanger 4 Ultrapure water production unit 5 Ultraviolet oxidizer 6 Ion exchanger 7 UF membrane separator 8 Pump 9 Use point

Claims (4)

  In an ultrapure water production system comprising at least an ion exchange device and a membrane separation device arranged on the downstream side thereof, a member constituting a water flow portion upstream of the ion exchange device is added to the ultrapure water production system. A method of mounting, after cleaning the member in advance so that the number of fine particles in the ultrapure water passed through the member when the ultrapure water is passed through the member is equal to or less than a predetermined value. A method for attaching components of an ultrapure water production system, wherein the component is attached to the ultrapure water production system.   2. The method for attaching components of an ultrapure water production system according to claim 1, wherein the fine particles are fine particles having a particle diameter of 0.05 [mu] m or more.   3. The ultrapure water production system according to claim 1 or 2, wherein the member is previously washed so that the number of fine particles in ultrapure water passed through the member is 10,000 / mL or less. A method for attaching components of the ultrapure water production system.   The ultrapure water production system according to any one of claims 1 to 3, wherein the member is one or more selected from the group consisting of a pump, a heat exchanger, a valve, and a meter. A method for attaching the constituent members.

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