JP4449080B2 - Cleaning method for ultrapure water production and supply equipment - Google Patents

Description

  The present invention is a cleaning of an ultrapure water production and supply device that produces and supplies ultrapure water widely used in electronic component manufacturing factories such as semiconductor devices, liquid crystal displays, silicon wafers, and printed circuit boards, nuclear power plants, or pharmaceutical manufacturing factories. In particular, the present invention relates to a method for cleaning up the apparatus.

  Conventionally, in the manufacturing process of electronic parts such as semiconductor devices, liquid crystal displays, silicon wafers, printed boards, power generation processes of nuclear power plants or pharmaceutical manufacturing processes, ionic substances, fine particles, organic substances, dissolved gases, viable bacteria, etc. Ultrapure water with extremely low impurity content is used. In particular, a lot of ultrapure water is used in the manufacturing process of electronic parts such as semiconductor devices, and the demand for the purity of ultrapure water is becoming more and more severe as the integration degree of semiconductor devices increases. Yes. For example, the specifications of the state-of-the-art ultrapure water for semiconductor manufacturing are: resistivity: 18.2 MΩ · cm or more, number of fine particles of 0.05 μm or more, 1 mL / mL or less, TOC: 1 μg / L (liter, the same applies below), metal 5 ng / L or less and the required water quality are strict, and further, for example, metal 1 ng / L or less and the required water quality tend to be stricter.

  Such high-purity water called ultra-pure water does not necessarily have a clear definition of “ultra-pure water”, but in general, pre-treatment equipment, primary pure water equipment, secondary pure water Manufactured with an ultrapure water production and supply system composed of devices (subsystems). With such a system, raw water such as industrial water, city water, and well water is processed to produce and supply ultrapure water. The pretreatment device turbidizes raw water using a coagulating sedimentation device, a sand filtration device or the like. The primary pure water device uses at least some of an activated carbon filtration device, a reverse osmosis membrane device, a two-bed three-column ion exchange device, a vacuum deaeration device, a mixed bed ion exchange device, a precision filter, etc. To remove primary impurities to obtain primary pure water. The secondary pure water apparatus (subsystem) should be referred to as an ultrapure water production apparatus in a narrow sense. Ultrapure water production and supply equipment temporarily stores primary pure water (primary) from a pure water storage tank through a subsystem consisting of various unit devices to the place of use and from the place of use to the pure water storage tank. It has a structure that forms a circulation system with a return return piping system. The place of use is called a use point (use point) in an electronic component manufacturing factory, a pharmaceutical manufacturing factory, or the like. In such an ultrapure water production and supply apparatus, the sub-system includes an ultraviolet oxidation apparatus for decomposing organic substances in the latter stage of the (primary) pure water storage tank, a cartridge polisher (CP) using a mixed bed ion exchange resin, and an ultrafiltration membrane apparatus. And the like.

  When the ultrapure water production and supply system or ultrapure water production and supply equipment is newly started up or when it is restarted after an outage due to periodic inspections, the above-mentioned impurities mixed and generated in the system are removed and the vicinity of the place where it is used The cleaning trial operation is performed until the ultrapure water in the water reaches a desired water quality. Accordingly, it is necessary to perform a cleaning test operation time from the start of the ultrapure water production and supply device until the desired ultrapure water can be used at the place of use. There is a strong demand for short-term start-up called a vertical start-up of the apparatus, that is, shortening the start-up period (that is, trial run / adjustment period). Cleaning methods include flushing and blowing with ultrapure water, circulation of ultrapure water, warm water cleaning, hydrogen peroxide water cleaning, alkali cleaning (basic aqueous solution cleaning), and functional water (such as ozone and hydrogen). A method of cleaning using water) and a surfactant is also proposed. Among various cleaning methods, an appropriate method is performed according to the object to be cleaned and the purpose. In order to obtain a sufficient cleaning effect, a plurality of cleaning methods may be implemented step by step in consideration of the effects of various cleaning methods.

Among the various impurities described above, a cleaning method including alkali cleaning has been proposed as a method for enhancing the ability to remove fine particles.
JP 2000-317413 A JP 2002-192162 A JP 2004-267864 A

  Japanese Patent Application Laid-Open No. 2000-317413 discloses a method of cleaning an ultrapure water production system with a basic cleaning solution that is an aqueous tetraalkylammonium hydroxide solution of about 10 to 100 ppm. A basic cleaning liquid is circulated in the system. After cleaning, the cleaning liquid is discharged, and then ultrapure water is introduced into the system to remove the remaining cleaning liquid. The treatment of the cleaning wastewater (drainage containing the cleaning liquid) generated at this time is, for example, adsorbed and removed with a weakly acidic cation exchange resin.

  Japanese Patent Application Laid-Open No. 2002-192162 defines a fine particle washing and removing process with a basic solution as "fine particle washing", a sterilization process with hydrogen peroxide as "sterilizing washing", and a chemical replacement with ultrapure water as "extrusion washing". In the method of cleaning the ultrapure water production system in the order of fine particle cleaning → (extrusion cleaning) → sterilization cleaning → extrusion cleaning, the extrusion cleaning after the microparticle cleaning is not performed at all, or the sterilization process is performed during the extrusion cleaning. Disclosed is a method for transferring (intentionally injecting hydrogen peroxide with the basic compound contained in the basic solution remaining in the system). The state in which the basic compound in the system is substantially completely discharged by the extrusion cleaning after the fine particle cleaning is when the pH in the system becomes neutral, but this method does not wait for this, for example, Hydrogen peroxide is injected when the pH is higher than 7 and lower than or equal to 9, preferably about 7.5 to 8.5. In extrusion cleaning, primary pure water is supplied to the tank, and is circulated appropriately in the system to discharge the cleaning liquid remaining in the system.

  Japanese Patent Application Laid-Open No. 2004-267864 discloses a method of performing alkali cleaning with a basic aqueous solution in a state where hydrogen peroxide remains after hydrogen peroxide cleaning (the method and process of Japanese Patent Application Laid-Open No. 2002-192162). Reverse order). In this method, “push-out cleaning” is defined as a general term for both “push-out” and “rinse”. If the basic compound is tetraalkylammonium hydroxide, such as ammonia, amine, tetramethylammonium hydroxide, etc., care must be taken not to exceed regulatory values such as the nitrogen release standard, and decomposition and detoxification with bioactive sludge Treatment, adsorption treatment with a cation exchange resin, and the like are appropriately performed.

  In the methods described in the above publications, (ultrafine) pure water is added to the system after the “fine particle peeling and dispersion step (fine particle cleaning defined in JP-A-2002-192162)” with a basic solution (alkaline cleaning liquid). To extrude and discharge the basic solution, and perform extrusion washing to remove the basic solution in the system. In other words, it extrudes and discharges simultaneously while receiving (ultra) pure water. In this case, the cleaning liquid or pure water becomes drainage, and the fine particles in the system are gradually discharged out of the system. Moreover, the pH of the water in the system containing the cleaning liquid gradually decreases and approaches 7 (neutral). Even when the cleaning liquid is made to have a high concentration of alkali (high pH), the pH is lowered during extrusion cleaning, and the effect of dispersing fine particles to prevent reattachment of fine particles by alkali is reduced. At this time, since the fine particles in the system are normally discharged while circulating with the water in the system, there is a high possibility that the fine particles remain in the system for a long time. The dispersion ability of the fine particles existing in the system in a state where the pH is lowered is not high. In addition, since the emphasis was not placed on “push-out cleaning” and blow rinsing was performed appropriately, the end point of push-out cleaning was not clear and it was difficult to obtain an accurate cleaning effect. In addition, there was a problem that the amount of drainage increased.

  The present invention makes it possible to shorten the cleaning trial operation time until the ultrapure water reaches the desired water quality when the ultrapure water production and supply device is newly started up or when it is restarted after a pause due to periodic inspection or the like. It aims at providing the washing | cleaning method of an ultrapure water production supply apparatus. Another object of the present invention is to provide a method for cleaning an ultrapure water production and supply device that enables a startup method suitable for working on site.

  The present inventor has conceived that the effect of alkaline cleaning with a basic cleaning solution is “peeling and dispersing” fine particles, not “removing” the fine particles, and removing the fine particles out of the system is a basic cleaning solution. It is an extrusion cleaning after the step of performing the cyclic cleaning by the method (extrusion and rinsing of the basic cleaning solution with pure water), and the completion of this step is considered to be the most important, and the present invention is completed. It was.

That is, in the present invention, at least a part of the wetted part of the ultrapure water production and supply device that processes primary pure water to produce ultrapure water and supplies it to the place of use is subjected to circulating cleaning with a basic cleaning liquid. Fine particle peeling / dispersing step, first extrusion cleaning step for extruding and rinsing basic cleaning solution with pure water, sterilization step for circulation and / or immersion cleaning with hydrogen peroxide cleaning solution, and hydrogen peroxide with pure water A method of cleaning an ultrapure water production and supply device that performs a second extrusion cleaning step of extruding and rinsing a cleaning liquid in this order ,
In the fine particle peeling / dispersing step and the first extrusion washing step, the filtration membrane module of the filtration membrane device of the ultrapure water production and supply device is bypassed or dummy, and the filtration membrane module is installed before the sterilization step is performed. And providing a cleaning method for an ultrapure water production and supply device , wherein the sterilization step and the second extrusion cleaning step are performed while the hydrogen peroxide cleaning liquid is filtered through the filtration module. .

Here, “extrusion” means that the chemical solution in the system (basic cleaning solution or hydrogen peroxide cleaning solution) is purged with pure water, that is, chemical replacement with pure water. The extrusion process time is almost the same without depending on it, and ideally, pure water equivalent to one volume of the system capacity is used. “Rinse” is a chemical solution that can be used even in the same system by exfoliating (rinsing) chemicals that adhere to the pipe surface or remain in the pipe pool or joints with pure water after extrusion. The cleaning time varies depending on the chemical concentration, and the higher the concentration, the longer the time required. In the “extrusion”, for example, the pure water storage tank is replaced with pure water, and then the pure water is poured into the subsystem at once using a pump and blown from the vicinity of the end of the return pipe. In the present specification, both “extrusion” and “rinsing” may be collectively referred to as “ extrusion cleaning”. Therefore, the process of extruding and rinsing the basic cleaning solution with pure water is the “first extrusion cleaning process”, and the process of extruding and rinsing the hydrogen peroxide cleaning solution with pure water is the “second extrusion cleaning process”. It shall also be said. In addition, “pure water” at the time of extrusion cleaning may be “ultra pure water”, and it may be considered that pure water or ultra pure water is used.

  Cleaning with a basic cleaning liquid is intended to facilitate the separation and dispersion of fine particles by changing the surface potential of the fine particles and electrically repelling the constituent materials of the system. In other words, the fine particles are electrostatically attached to the pipe or the like due to the surface potential, but when the pH of the liquid is changed to the alkaline side, the fine particles are negatively charged and the charge is increased. Organic polymer materials such as polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), and polyphenylene sulfide (PPS) that constitute equipment systems and piping systems do not cause surface charge changes and are related to the pH of the liquid. Therefore, both of them are electrically repelled, and the fine particles are easily peeled and dispersed. In addition to such a chemical cleaning effect, in the cleaning with a basic cleaning solution, physical removal, peeling, and diffusion effects due to the flow are important. In addition, the cleaning with the hydrogen peroxide cleaning solution is intended for sterilization to bring the number of viable bacteria to the required water quality level.

  As described above, the performance of the first extrusion cleaning step after the step of performing the circulating cleaning with the basic cleaning liquid is the most important, so that the rinsing is sufficiently performed at this stage. While rinsing until the pH of the rinsing drainage is substantially 7 neutral, the rinsing drainage is preferably discharged out of the circulation system of the ultrapure water production and supply device. The circulation system of the ultrapure water production and supply equipment here refers to the piping system that reaches the place of use through the subsystem consisting of various unit devices from the pure water storage tank that stores primary pure water and the place of use from the place of use. A loop consisting of a return piping system that returns ultrapure water to the pure water storage tank (ultra pure water circulation system), and usually blows (discharges) extruded and rinse wastewater from the vicinity of the end of the return piping. It is preferable to carry out at least a part of the process of extruding and rinsing the basic cleaning solution with pure water all at once without circulating the water in the circulation system of the ultrapure water production and supply apparatus. By this step, the fine particles that have been “peeled and dispersed” by the basic cleaning solution are pushed out of the system without being reattached and discharged together with the washing water, so that the effect of removing fine particles can be achieved more reliably. It is preferable because the extrusion cleaning can be completed in a short time. Similarly, after cleaning with the hydrogen peroxide cleaning solution, at least part of the process of extruding and rinsing the hydrogen peroxide cleaning solution with pure water is performed at once without circulating the water in the circulation system of the ultrapure water production and supply device. It is preferable to carry out. In addition, as in the method of Japanese Patent Laid-Open No. 2002-192162, in the method in which the extrusion cleaning after the fine particle cleaning is not performed at all, or the method moves to the sterilization process in the middle of the extrusion cleaning, the result of the fine particle removal in the extrusion cleaning step. Is insufficient, and the pH of the hydrogen peroxide cleaning liquid used in the sterilization process is acidic at about 5-6. Therefore, when the hydrogen peroxide cleaning liquid is allowed to flow through the ultrapure water production and supply apparatus with the fine particles remaining, There is a risk of re-adhering to the piping or the like, and in this case, shortening the cleaning trial operation time cannot be realized.

Basic compounds (alkali agents) used in the preparation of the basic cleaning liquid include ammonia, amines, ammonium compounds such as tetraalkylammonium hydroxide, tetraalkylammonium carbonate, tetraalkylammonium bicarbonate, and alkali metal hydroxides ( (NaOH or KOH), alkali metal oxides, carbonates (for example, Na ₂ CO ₃ ), bicarbonates (for example, NaHCO ₃ ), and the like can be used alone or in combination. Examples of amines include monomethylamine, dimethylamine, trimethylamine, and monoethanolamine. Tetraalkylammonium hydroxide is a strongly basic quaternary ammonium compound that does not contain a metal element in its molecular structure. Typical examples include tetramethylammonium hydroxide (TMAH) and choline. Further, 2- (2-hydroxyethoxy) ethyltrimethylammonium hydroxide (DECH) and 2- [2- (2-hydroxyethoxy) ethoxy] ethyltrimethylammonium hydroxide (TECH) hydroxide can also be used.

  As such a basic compound, tetraalkylammonium hydroxide such as TMAH or choline, amines, or ammonia is preferable, and an aqueous solution containing these as basic compounds is preferably used as the basic cleaning solution. It is more preferable to use tetraalkylammonium hydroxide such as TMAH or choline because it is a strong base, and a high pH aqueous solution can be obtained with a small amount, and TMAH is particularly preferable. In addition, as described later, since it is not necessary to prepare a basic cleaning solution having a high pH, an aqueous solution having a desired pH can be obtained even in a small amount using ammonia, and the problem of odor is small in a cleaning solution having a low ammonia concentration. Ammonia is not particularly a TOC source, but ammonia is also particularly preferable in terms of ease of processing and influence on the environment. The alkali metal hydroxides, alkali metal oxides, carbonates, and bicarbonates mentioned above are said to be a trace amount of metals adversely affecting product yield in the electronics industry such as semiconductor manufacturing factories. Hard to use for safety. Therefore, it is preferable to use tetraalkylammonium hydroxide, amines or ammonia in the electronic industry. Further, a small amount of a surfactant may be used in combination with the basic compound. Further, the fine particles of gases such as oxygen gas, hydrogen gas, nitrogen gas and the like may be coexisted with the basic cleaning solution in the basic cleaning solution, so that the fine particles can be more effectively separated and removed. .

  The pH of the basic cleaning solution is preferably more than 7 and 10 or less, and more preferably in the range of 8-10. Alkali has an effect on the separation and dispersion of fine particles, and it has been considered preferable for fine particle removal to be washed with a basic cleaning solution having a high concentration of alkali (high pH), but this is not necessarily the case. Further, the above range is preferable in view of the fact that when the alkali concentration is increased, problems are likely to occur in the cleaning chemical solution cost, the handling property (safety) of the cleaning solution, the disposal method of the cleaning waste water, and the like. What is important is that the fine particles that have been peeled off and dispersed in the system with the basic cleaning solution and discharged in the system are surely discharged (rinsed) out of the system in the first extrusion cleaning process. It is not to increase the concentration and enhance the effect of peeling and dispersing fine particles.

  Most of the ultrapure water production and supply systems that are the targets of vertical startup are new systems. Therefore, when the system is started up, the wastewater treatment equipment may not be fully started up. In particular, when basic compounds (alkali) such as ammonia, amines, TMAH, etc. are used for the cleaning liquid, cleaning including these In general, an apparatus for treating waste water has not been started up yet. In other words, it is normal to start up the production equipment after the startup of ultrapure water, and since the actual wastewater containing various chemicals comes out after the start of production, the main wastewater treatment equipment is around that time. Launched. In this case, when a basic cleaning solution containing high concentrations of ammonia, amines, TMAH, etc. (high pH) is used, there arises a problem with respect to the subsequent waste water treatment. That is, ammonia, amines, TMAH, etc. contain nitrogen, and amines, TMAH, etc. are also TOC sources. Therefore, depending on the concentration, it may be necessary to perform wastewater treatment in addition to pH neutralization. However, this is not the case when an inorganic alkali such as NaOH or KOH is used. Therefore, in the method of each of the above publications, it is shown that a weakly acidic cation exchange resin is used to adsorb and remove the TMAH-containing wastewater. However, at the site, the system has a large amount of water, a large amount of basic cleaning solution is prepared, and several to several tens of times of waste water is generated by the extrusion cleaning process. It is not easy to install an adsorption / removal device using an exchange resin and perform wastewater treatment, and the treatment becomes more difficult as the alkali concentration of the basic cleaning liquid is higher. That is, when the alkali concentration of the basic cleaning liquid is high, not only the drainage concentration is high, but also the amount of drainage generated at the rinsing stage of the extrusion cleaning is increased. On the other hand, a wastewater treatment device (for example, an acid or alkali neutralization device, etc.) generated by the operation of a water treatment device such as a pretreatment device or a primary pure water device is started up early from the start of the water treatment device operation. It is common. Therefore, in this case, when ammonia, amines, TMAH, or the like is used for the basic cleaning liquid, it can be discharged by neutralization or the like with the above processing apparatus if the concentration is sufficiently low. On the other hand, if the concentration is high, it cannot be discharged by neutralization alone, and even if it satisfies the discharge standard by dilution, it must be diluted with a considerable amount of water, and a tank for holding a large volume of wastewater ( Problems such as inability to secure a water tank) occur. In this way, the waste water of the basic cleaning liquid containing high concentrations of ammonia, amines, TMAH and the like cannot be disposed of by simple treatment such as neutralization, but in the present invention, the alkali concentration of the basic cleaning liquid can be lowered. Effluent can be easily treated by neutralizing and discharging. In the case of extruding and washing in the course of circulation as in the conventional method, the amount of extrusion and rinsing drainage increases as the rinsing is completed, but it is discharged without circulation, and the pure water storage tank is replaced with pure water. Then, the amount of drainage can be greatly reduced even when trying to completely rinse by flushing out the inside of the system. The wastewater containing hydrogen peroxide generated in the second extrusion cleaning process after the process of circulating and / or immersion cleaning with the hydrogen peroxide cleaning solution is discharged after the hydrogen peroxide is decomposed with catalase or the like. Is done.

  As the hydrogen peroxide cleaning liquid, a hydrogen peroxide solution having a high concentration of 0.1 to 5% by weight can be generally used although it depends on the water temperature. The preferable hydrogen peroxide concentration of the hydrogen peroxide cleaning liquid is 1 to 3% by weight.

  According to the present invention, fine particles (dispersed during basic cleaning) are removed from the system by sufficiently and substantially completely performing the first extrusion cleaning step of extruding and rinsing the basic cleaning solution with pure water. By removing it reliably, it is possible to reduce the cleaning trial run time until the ultrapure water produced and supplied reaches the desired water quality when the ultrapure water production and supply equipment is newly started up or when it is restarted after a periodical shutdown. It is possible to shorten the time, and it is possible to provide a start-up method suitable for working in the field.

  By performing the first extrusion cleaning process of extruding and rinsing the basic cleaning solution with pure water all at once without circulating the water in the circulation system of the ultrapure water production and supply device, the chemical solution containing fine particles can be obtained all at once. In addition, the amount of pure water required for extrusion cleaning (= the amount of wastewater generated) and the working time can be reduced. Although the pH drop in the system is rapid, the fine particles are extruded and removed together with a high concentration chemical solution, so even if the effect of preventing the reattachment of the fine particles is reduced due to the pH drop, the fine particles are substantially present there. There is no problem because it is gone or the amount is low. The second extrusion cleaning process for extruding and rinsing hydrogen peroxide is also performed at once without circulating the water in the circulation system of the ultrapure water production and supply device, so that chemicals, contaminants, exfoliation and extract can be removed. It can be removed at once, and the amount of pure water required for extrusion cleaning (= the amount of waste water generated) and the working time can be reduced. Even in the case of wastewater treatment, if the amount of wastewater is small, there is a great merit because the wastewater tank can be sufficiently retained and the wastewater treatment can be performed slowly.

  A low-concentration alkaline basic cleaning solution is sufficiently effective for the separation and dispersion of fine particles in the ultrapure water production and supply apparatus of the ultrapure water system. When the concentration is low, the cost of alkaline chemicals is low, the handling (safety) of the basic cleaning liquid is good, the wastewater generated by the extrusion cleaning can be easily treated, and the amount of drainage can be reduced. In particular, wastewater treatment is very advantageous if it can be neutralized and discharged. With regard to this wastewater treatment, cleaning wastewater (including rinse wastewater) is blown out in a short time by pushing out the amount held in the system and discharged. On the other hand, the capacity and scale of the wastewater treatment equipment is determined by the amount of wastewater actually discharged from various equipment, and the amount of washing wastewater per unit time during extrusion cleaning exceeds the design wastewater treatment capacity (treatment capacity). There is. Therefore, even if a device for wastewater treatment such as a neutralization facility has already been started up, its capacity is insufficient, and the wastewater from the extrusion cleaning that occurs temporarily in large quantities is sent to other storage tanks such as emergency drainage tanks. It is necessary to possess. There are restrictions on storage tanks that can temporarily receive wastewater, and there are limits to the amount of water retained. For this reason, reducing the concentration of the basic cleaning liquid and reducing the amount of waste water generated by extrusion cleaning is an important advantage even when the waste water treatment facility has already been started up.

  Next, although embodiment of invention is described, this invention is not limited to these.

  Ultrapure water production and supply equipment is usually a pure water storage tank from a piping system that reaches a place of use through a subsystem having various unit devices from a pure water tank (tank) that temporarily stores primary pure water. It has a structure that forms a circulation system with a return piping system. FIG. 1 is a flowchart illustrating an example of a subsystem. In FIG. 1, a heat exchanger 1 for adjusting the water temperature, an ultraviolet oxidation device 2 for decomposing organic matter, and a non-regenerative mixed bed ion exchange resin tower for desalting are used as the various unit devices described above. A cartridge polisher (CP) 3 and an ultrafiltration (UF) membrane device 4 for removing fine particles are used. A bypass pipe 5 for bypassing CP3 is provided. A microfiltration membrane device or the like may be used as the filtration membrane device instead of the UF membrane device 4. For example, a membrane degassing device, a booster pump, an ion adsorption membrane device, or the like may be further arranged between the CP3 and the UF membrane device 4 in the above system. In general, a valve (not shown) is opened and CP3 is bypassed by the bypass pipe 5, and during the chemical cleaning with the basic cleaning solution or the hydrogen peroxide cleaning solution and the subsequent extrusion cleaning, the ultrapure water production and supply apparatus is circulated. Wash the entire system and switch to CP3 water flow after sufficient rinsing. Instead of bypassing CP3, CP3 is not filled with ion exchange resin from the beginning, and the entire circulation system can be sufficiently cleaned and rinsed, and then CP3 is filled with ion exchange resin and washed with pure water. Good. This is because an ion component such as a base becomes an ion load of CP3, and hydrogen peroxide causes oxidative degradation of the ion exchange resin of CP3. The lamp of the ultraviolet oxidizer 2 during chemical cleaning is generally turned off, but the lamp of the ultraviolet oxidizer 2 may be turned on during extrusion cleaning of the hydrogen peroxide cleaning liquid.

FIG. 2 is a piping diagram showing an example of an ultrapure water production and supply apparatus including the subsystem as shown in FIG. The primary pure water is sent to the pure water storage tank 11 through the line L1. The pure water storage tank 11 and the lines L2 and L3 constitute a tank circulation system (chemical solution preparation circulation system) and are used when preparing a uniform chemical solution. The shower ball 12 sprays liquid also on the inner wall of the pure water storage tank 11. During normal operation, the valve V2 on the line L7 is closed. At the time of new start-up or at the time of re-start-up after a pause due to periodic inspections, etc., a line L8 is temporarily installed at the end of the valve V2, the valve V2 is opened, and the basicity of alkali chemicals such as TMAH and ammonia via the lines L8 and L7 A predetermined amount of each of the cleaning stock solution (concentrated chemical solution) or the hydrogen peroxide stock solution (concentrated chemical solution) is injected into the line L2. At that time, the flow rate of the concentrated chemical solution and the circulating fluid is adjusted by adjusting the opening degree of the valve V3 on the line L2, and stored in the pure water storage tank 11 via the line L3 where the valve V5 is opened by the pump P. The concentrated chemical solution is introduced into the pure water and mixed with pure water by circulating through the tank circulation system to prepare a uniform chemical solution. At this time, the valve V4 is preferably closed. Examples of the concentrated chemical solution injection procedure, for example, span the concentrated chemical solution to clean container and washed, and injected through a temporary setting line L8, such as a tube, pure water in the container so as to prevent air from entering When the liquid becomes less A predetermined amount of concentrated chemical solution can be injected by repeating the operation of injecting the remaining chemical solution. Further, after each of the concentrated liquid injection is cleaning line L8, line L7 with pure water, closing the valve V2, the temporary setting line L8 is removed. When cleaning (rinsing) the inner wall of the pure water storage tank 11 with pure water, the valves V1 and V6 are closed, the valve V7 is opened, and primary pure water is preferably sprayed from the shower ball 12 through a line branched from the line L1. When the prepared chemical solution is used for cleaning, the valves V2 and V5 are closed, the valve V4 is opened, the chemical solution is sent to the subsystem 13 by the pump P, and a line L4, which is a piping system that sends ultrapure water to the place of use, The chemical solution is distributed to the circulation system of the ultrapure water production and supply device including the line L5 which is the return point piping system for returning the remaining ultrapure water. The line L6 is a bypass line used for blowing at a stroke in the initial stage of extrusion cleaning. When this is used, the valve V8 is closed and the valve V9 is opened. The valve V10 is a pressure control valve, and controls the pressure and flow rate during circulating cleaning and normal operation. During drainage blow, the valve V11 is opened and the valve 12 is closed, but during normal operation of the circulation system, the valve V12 is opened and the valve 11 is closed. The meter 14 is a measuring meter that measures water quality such as pH, conductivity, or resistivity. In FIG. 2, the measuring instrument 14 is on the branched sampling line L9, but may be on the main line such as the line L5. In the case of branching, each water quality may be measured online or offline. Further, the measuring instrument 14 may be temporarily installed for the apparatus start-up test operation instead of being always installed.

  The pipe length from the use point feed line L4 from the outlet of the subsystem 13 to the end of the use point return line L5 (that is, the total pipe distance of the lines L4 and L5) is considerably long, and the internal capacity of the pipe is also large. In the case of a circulation system via the bypass line L6, the piping length of the line from the outlet of the subsystem 13 to the return to the pure water storage tank 11 can be greatly shortened. At the beginning of extrusion cleaning, cleaning in the subsystem 13 can be confirmed in a short time by performing cleaning blow without circulating pure water through the bypass line L6. Since the use point piping is long and complicated, it takes a relatively long time to complete the cleaning of the use point piping. Although sterilization with hydrogen peroxide solution is effective even with chemical solution immersion, since the constituent materials of the subsystem 13 are diverse, it is desirable to avoid long-time hydrogen peroxide chemical solution immersion in the subsystem 13. Therefore, the hydrogen peroxide cleaning solution is washed out in a short time by using the bypass line L6, for example, the valve 8 and the valve 13 are closed, and the hydrogen peroxide solution is sealed in the use point pipe, so that the immersion treatment is performed for a long time. Therefore, it is desirable to sterilize surely. Using the time for which the hydrogen peroxide solution is sealed and immersed in the use point piping, cleaning (rinsing) of the subsystem 13 is completed via the bypass line L6, and CP3 is filled with ion exchange resin, CP3 It is also possible to start up the unit device first, such as cleaning blow of the UF membrane device 4 or cleaning blow of the UF membrane device 4.

Generally speaking, the cleaning chemical solution is prepared by adding a basic compound such as TMAH or aqueous ammonia or hydrogen peroxide into the system from any location in a pure water storage tank or circulation system. Any substance that can be supplied as a gas component, such as ammonia, may be added in the form of a gas as it is. The pure water storage tank and the pure water in the system are mixed to adjust to a predetermined chemical concentration, and are circulated in the system in accordance with a normal (ultra) pure water circulation flow to clean the entire ultrapure water production and supply apparatus. A chemical solution tank other than the pure water storage tank may be prepared, and a cleaning chemical solution may be prepared therein, and the cleaning chemical solution may be circulated in the ultrapure water circulation system. In FIG. 2, (alkali agent or H2O2 such as TMAH or ammonia) drug from the drug infusion line L8 provisional set connected to the line L7 branched from the line L2 from the pure water storage tank 11 is injected, the tank circulation system (solution In the process of circulating through the preparation circulation system, pure water and chemicals are mixed to prepare a uniform cleaning chemical solution.

  Fine particle cleaning with a basic cleaning solution which is a basic aqueous solution is performed by circulating for about 0.5 to 8 hours. The primary purpose of the basic aqueous solution cleaning is to remove fine particles. Therefore, in addition to the chemical cleaning effect by the basic cleaning liquid, physical removal, peeling, and diffusion effects by the flow are important. Thereafter, extrusion cleaning with pure water is performed until the pH becomes neutral, for example.

  When cleaning with a hydrogen peroxide cleaning solution, which is a hydrogen peroxide solution, circulation is performed for about 0.5 to 8 hours. Since the main purpose of cleaning with hydrogen peroxide is sterilization (chemical effect), viable bacteria and biofilm (such as plumbing and ancillary equipment at the point of use) It is important to come into contact with the ultrapure water contact surface that contains both living and dead bacteria and adherents made of bacterial product. Therefore, it is preferable to circulate the chemical solution because it has a physical effect. However, after the hydrogen peroxide has spread throughout the system, the pump is stopped for a certain period of time and the system is immersed in the hydrogen peroxide solution. Even if immersion sterilization is performed, a high sterilization effect can be expected. If sufficient sterilization is required and there is time to supply ultra-pure water to the point of use, etc., after circulation for about 0.5-8 hours, further with chemical solution in the system for several hours or more For example, you may immerse for half a day (overnight) to 1 day. Thereafter, extrusion cleaning with pure water is performed.

  As for the circulation flow rate in the circulation system of each cleaning chemical solution of basic cleaning solution and hydrogen peroxide cleaning solution, the physical force due to flow is stronger at higher speeds and a higher cleaning effect can be expected, but in order to flow at high flow rate, it is a pump. Since the capacity becomes large, in practice, a general linear velocity range for transferring an aqueous liquid, for example, preferably 0.1 to 3.0 m / second, more preferably 0.5 to 2. It is better to flow at 0 m / sec. In the cleaning method of the present invention, in addition to circulation and immersion, for example, in a state where the cleaning solution of the ultrapure water production and supply device is filled with the chemical solution, the cleaning effect is obtained by applying minute vibrations to the chemical solution by ultrasonic waves or the like. You may take the method of raising.

  The temperature of the chemical solution at the time of cleaning is not particularly limited, but it is preferable from the viewpoint of cleaning power that the temperature is higher as long as it does not exceed the heat resistance temperature of piping, equipment, etc. constituting the ultrapure water production and supply apparatus. For example, the basic cleaning solution can be in the range of 10 to 100 ° C., and when polyvinyl chloride (PVC) having a heat resistant temperature of about 45 ° C. is used as a constituent material, the chemical solution temperature is about 40 ° C. When polyvinylidene fluoride (PVdF) having a temperature of about 80 ° C. is used as a constituent material, the chemical temperature can be increased to about 75 to 80 ° C., and when stainless steel is used as a constituent material, the temperature can be increased to near 100 ° C. The hydrogen peroxide cleaning liquid may also be heated and is preferably used for cleaning at a liquid temperature of 20 to 60 ° C., depending on the constituent materials. However, the chemical temperature is often the result of the water temperature and sometimes the normal temperature.

  In such an ultrapure water production and supply device, during the first extrusion cleaning step, the quality of at least the rinse wastewater in the extrusion wastewater and rinse wastewater of the basic cleaning liquid is confirmed, and the circulation system of the ultrapure water production and supply device It is preferable to discharge the rinse waste water out of the system while rinsing with pure water until the influence of the basic cleaning solution is eliminated. The quality of at least the rinse waste water in the extrusion waste water and rinse waste water of the basic cleaning liquid should be checked at the end of the ultrapure water circulation system, that is, near the end of the return pipe, or at the blow line. It is preferable for removal, and it is simple and preferable to measure by pH, conductivity or resistivity, and rinsing is sufficiently performed until satisfactory by such water quality confirmation. By confirming the water quality (pH, etc.) of the extrusion / rinsing waste water, the fine particles dispersed in the basic cleaning liquid can be reliably discharged and removed. The rinse waste water is preferably discharged out of the circulation system while rinsing until the pH of the rinse waste water becomes substantially 7 neutral. In FIG. 2, the instrument 14 measures pH, conductivity, resistivity, and the like.

In fine peeling and dispersing step and the first extrusion washing step, filtration membrane module of the filtration membrane apparatus for producing ultrapure water supply device and a dummy or bypass. In each of the above-mentioned publications, the handling of the ultrafiltration membrane device of the ultrapure water production system is not clearly stated, and the ultrafiltration membrane (UF membrane) module is in principle installed with other components of the system. Cleaning is performed together (however, JP 2004-267864 A describes that a dummy module may be installed during chemical cleaning). A filtration membrane such as a UF membrane has a large membrane area (contact area). Therefore, when the cleaning liquid comes into contact with the membrane surface, there is a possibility that the membrane is contaminated. In particular, since the basic cleaning liquid is conductive, alkali is adsorbed on the inside or inside of the filtration membrane, and the rise in resistivity at the outlet of the filtration membrane device during startup tends to be slow. Accordingly, when the filtration membrane module is installed at the time of cleaning with the basic cleaning liquid, it is better that the alkali concentration of the basic cleaning liquid is lower in consideration of the subsequent rise in resistivity. Moreover, you may use a dummy module (The shape is a module and the film | membrane does not contain) as a filtration membrane module.

On the other hand, the sterilization process using the hydrogen peroxide cleaning solution has the same advantage if the concentration is low. However, if the concentration of hydrogen peroxide is lowered, the sterilizing power is lowered, so that the concentration cannot be reduced so much. However, since hydrogen peroxide has less influence on resistivity than alkali chemicals and is not included in the specifications (standard) of ultrapure water, a high concentration hydrogen peroxide cleaning solution may be used for cleaning. Therefore, before carrying out the sterilization process that performs circulation and / or immersion cleaning with hydrogen peroxide cleaning liquid, install a filtration membrane module such as a UF membrane module and perform the sterilization process while filtering the hydrogen peroxide cleaning liquid through the filtration membrane. It intends line. If the filtration membrane module is installed before the cleaning with the basic cleaning solution, the filtration membrane may be contaminated as described above, so the fine particle peeling / dispersing step with the basic cleaning solution and the first extrusion cleaning step In the case where the filter membrane module is used as a dummy module and the filter membrane module is installed before the sterilization process using the hydrogen peroxide cleaning solution, it is particularly peroxidized after the fine particles have been reliably removed from the system by alkali cleaning + extrusion cleaning. Fine particles generated during hydrogen water circulation (especially from the pump) can be removed by cutting with a filtration membrane such as a UF membrane and not moved to the piping on the point of use. Also, sterilization of the filtration membrane itself such as a UF membrane can be performed. It can be done at the same time.

  In addition to the method of cleaning the entire ultrapure water production and supply equipment as described above, some of the ultrapure water production and supply equipment such as individual devices such as filtration membrane devices and UV oxidation equipment, pipes, and pipe joints You may wash separately. The cleaning may be performed by injecting the chemical solution immediately before the portion to be cleaned and discharging the chemical solution immediately after that, or by applying vibrations such as ultrasonic waves while the chemical solution is filled. For example, hydrogen peroxide water cleaning may be performed as such individual cleaning, and cleaning with a basic aqueous solution may be performed on the entire ultrapure water production and supply apparatus, or vice versa. In addition, it can be used for cleaning filtration membrane devices and prefabricated pipes just before new construction and assembly, and it is possible to effectively shorten the new startup cleaning time.

  Next, an example of a specific embodiment of the method of the present invention will be described. In the following, “tank circulation” means the circulation for mixing in the tank circulation system composed of the pure water storage tank 11 and the lines L2 and L3, and “system circulation” means the subsystem 13, the line L4, the use point piping system, the line Let us say the circulation in the circulation system of the entire ultrapure water production and supply apparatus (system) including L5. It is convenient to install a return line from the UF membrane device as appropriate. The hydrogen peroxide concentration can be confirmed using, for example, a hydrogen peroxide concentration test paper (available from Hishoe Chemical Co., Ltd.). Other water quality checks can be performed, for example, with a pH meter, pH test paper, TOC meter, resistivity meter, fine particle meter, or the like.

<1> When the installation of equipment and piping work are completed, the pure water storage tank 11 is prepared to receive primary pure water and is completed.
<2> Filling the entire system with primary pure water from the pure water storage tank 11, evacuating equipment and piping, and discharging large dust and impurities by flushing.
<3> An alkaline chemical (basic compound) is added and mixed by tank circulation to prepare a uniform chemical solution, and then the obtained basic cleaning liquid is system circulated. In order to increase the fine particle peeling effect, the circulation rate is preferably a high flow rate. At this time, it is desirable to bypass CP3 or unfill the ion exchange resin and use a dummy module for the UF membrane device 4.
<4> The chemical solution is discharged from the tank circulation system through a piping line and a tank blow line (not shown) and replaced with pure water. Residual chemical solution in the tank circulation system is confirmed by water quality such as pH (for example, pH <8, preferably 7). On the other hand, waste water is treated (neutralized and / or moderately diluted) and discharged.
<5> The cleaning liquid in the system is pushed out with the pure water stored in the pure water storage tank 11 and rinsed, and the fine particles and impurities dispersed in the cleaning liquid are discharged at once. At this time, it is preferable that water (liquid) is not circulated but blown out of the system. Wastewater is discharged (neutralized) and discharged.
<6> The residual chemicals in the system water or waste water is measured by measuring the water quality such as pH to check whether the rinse is sufficient (for example, pH <8, preferably 7). The position of the water quality measurement is preferably on the sampling line L9 branched from the end of the line L5 of the return piping system, that is, before returning to the pure water storage tank 11, like the instrument 14.
<7> A UF membrane module is installed.
<8> Hydrogen peroxide solution is added and mixed by tank circulation to prepare a uniform chemical solution, and then the obtained hydrogen peroxide cleaning liquid is system circulated. In some cases, it is immersed in a hydrogen peroxide cleaning solution (for example, the valves V8 and V13 are closed and only part of the line L4, the use point piping system, and the line L5 is immersed).
<9> The chemical solution is discharged from the tank circulation system through a piping line or a tank blow line (not shown) and replaced with pure water. The H ₂ O ₂ concentration in the tank circulation system is confirmed with a hydrogen peroxide concentration test paper or the like. The waste water is treated with waste water (decomposition treatment with catalase), the H ₂ O ₂ concentration is confirmed, and if the treatment is sufficient, it is discharged.
<10> The cleaning liquid in the system is pushed out with pure water stored in the pure water storage tank 11 and rinsed to check the H ₂ O ₂ concentration. At this time, it is preferable that water (liquid) is not circulated but blown out of the system. The waste water is treated with waste water (decomposition treatment with catalase), the H ₂ O ₂ concentration is confirmed, and if the treatment is sufficient, it is discharged.
<11> CP3 is filled when the ion exchange resin is not filled, and in the case of bypass, the bypass pipe is closed and pure water is passed.
<12> Blow at the outlet of CP3 to check the quality of the blown water. When the water quality reaches the specified value, close the blow pipe and send it to the subsequent stage (check the water quality with an appropriate instrument).
<13> Blow at the outlet of the UF membrane device to check the quality of the blown water. When the water quality reaches the specified value, close the blow pipe and send it to the subsequent stage (check the water quality with an appropriate instrument).
<14> Measure the return water quality (resistivity, TOC, fine particles, etc.) and if it is confirmed that the water quality can be returned to the circulation system (normal operation), close the valve V11, open the valve V12, and switch to the circulation line Normal operation.

Next, Example 1 of the present invention will be described. The ultrapure water production and supply apparatus was started up and washed according to the following series of operations (processes). The temperature of the water (liquid) was assumed to be a normal temperature without temperature control by a heat exchanger.
<1> Ultrapure water production and supply equipment (system) was filled with pure water, flushed, and vented.
<2> A TMAH basic cleaning solution having a pH of less than 10 was prepared in a pure water storage tank.
<3> The entire system was circulated and washed with a TMAH basic cleaning solution. The main line water supply flow rate was 0.5 m / sec, the circulation time was 3 hours, and the return pH was 9.7. At this time, CP was bypassed, and a dummy module was used for the UF membrane device.
<4> The inside of the pure water storage tank was replaced with pure water in 2.5 hours, and the final pH was 6.9. The waste water generated at that time was neutralized so as to be less than the regulated value and discharged.
<5> TMAH in the system was pushed out with pure water in the pure water storage tank at a stretch for 0.25 hours. The main line water flow rate was 0.5 m / sec. At this time, water (liquid) was not circulated but blown out of the system. The blown waste water was neutralized so as to be below the regulation value and discharged.
<6> While confirming the quality of the extruded waste water and the rinse waste water in the circulation system or on the blow line, the water was rinsed until the pH became 7, and the extrusion washing was sufficiently performed for 3 hours. The main line water flow rate was 0.5 m / sec.
<7> A UF membrane module was installed in the UF membrane device.
<8> A 1 wt% hydrogen peroxide cleaning solution was prepared in a pure water storage tank.
<9> The entire system was circulated and washed with a hydrogen peroxide cleaning solution for 2 hours. The main line water flow rate was 0.5 m / sec. At this time, CP was bypassed, and water was passed through the UF membrane module in the UF membrane device. The collected water at the farthest point of the use point pipe was measured with a hydrogen peroxide concentration test paper, and it was confirmed that H ₂ O ₂ had spread throughout the system.
The <10> use point piping system was closed and immersed and washed for 9.5 hours, during which the steps <11> to <12> were performed.
<11> The pure water storage tank was replaced with pure water. It was confirmed that the final H ₂ O ₂ concentration was 0 ppm by measuring with a hydrogen peroxide concentration test paper whether the pure water was sufficiently substituted. The wastewater was discharged after being decomposed with Olsorb (registered trademark), a hydrogen peroxide decomposition agent manufactured by Organo Corporation.
<12> The use point piping was bypassed, and the hydrogen peroxide in the system including the subsystem was extruded and rinsed at once with pure water in the pure water storage tank. The main line water flow rate was 0.5 m / sec. At this time, water (liquid) was not circulated but blown out of the system. The H ₂ O ₂ concentration of the wastewater was measured with a hydrogen peroxide concentration test paper and confirmed to be 0 ppm. The wastewater was discharged after being decomposed by orthosorb.
<13> The use point piping system was opened and subjected to extrusion cleaning for 4 hours. The main line water flow rate was 0.5 m / sec. At this time, water (liquid) was not circulated but blown out of the system. The H ₂ O ₂ concentration of the wastewater was measured with a hydrogen peroxide concentration test paper and confirmed to be 0 ppm. The wastewater was discharged after being decomposed by orthosorb.
<14> CP closed the bypass piping and passed the primary pure water.
<15> Blowing was performed at the CP outlet, and the quality of the blown water was checked. When the water quality reached the specified value, the blow pipe was closed and sent to the subsequent stage (water quality was checked with the instrument).
<16> Blowing was performed at the outlet of the UF membrane module of the UF membrane device, and the quality of the blown water was confirmed. When the water quality reached the specified value, the blow piping was closed and sent to the subsequent stage (water quality was confirmed with a meter).
<17> Return water quality (resistivity, TOC, fine particles, etc.) was measured, and it was confirmed that the water quality could be returned to the normal operation circulation system, and then switched to the circulation line for normal operation.

  Within 1 day from the start of normal circulation operation after cleaning is completed, the standard value of resistivity = 18.2 MΩ · cm or more, TOC = 1 ppb, particle size 0.05 μm or more = 1 standard / mL Achieved. The number of fine particles was measured using a fine particle meter DI-50 manufactured by PMS as a monitor instrument. Moreover, the viable cell count at the time of sampling for the first time two days after the start of normal circulation operation achieved a reference value of less than 1 / L. The sampling point for the sample water was the outlet of the UF membrane device.

  As described above, in Example 1, the TMAH in the system was extruded and washed at once without being circulated with pure water, and hydrogen peroxide was also extruded and washed, so that it was possible to obtain a good water quality in a short time. .

  The ultrapure water production and supply apparatus was started up and washed according to the same series of operating procedures as in Example 1, except that an ammonia basic cleaning solution having a pH of less than 10 was used instead of the TMAH basic cleaning solution used in Example 1. It was. A result substantially similar to that of Example 1 was obtained.

  According to the present invention, when the ultrapure water production and supply apparatus is newly started up or at the time of re-startup after a suspension by periodic inspection or the like, the cleaning trial operation time until the ultrapure water reaches the desired water quality can be shortened, Enables a start-up method suitable for on-site work. Accordingly, the present invention provides a cleaning method at the time of start-up of an ultrapure water production and supply apparatus widely used in an electronic component manufacturing factory such as a semiconductor device, a liquid crystal display, a silicon wafer, and a printed circuit board, a nuclear power plant, or a pharmaceutical manufacturing factory. It can be applied as

FIG. 1 is a flowchart illustrating an example of a subsystem. FIG. 2 is a piping diagram showing an example of an ultrapure water production and supply apparatus including the subsystem as shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Ultraviolet oxidizer 3 Cartridge polisher 4 Ultrafiltration membrane apparatus 11 Pure water storage tank 12 Shower ball 13 Subsystem

Claims (3)

A fine particle peeling / dispersing step in which at least part of the wetted part of the ultrapure water production and supply device that processes primary pure water and supplies it to the place of use is circulated and washed with a basic cleaning solution, A first extrusion cleaning process for extruding and rinsing a basic cleaning solution with pure water, a sterilization process for circulating and / or immersion cleaning with a hydrogen peroxide cleaning solution, and an extrusion and rinsing of a hydrogen peroxide cleaning solution with pure water. A method for cleaning an ultrapure water production and supply device that performs the second extrusion cleaning step in this order ,
In the fine particle peeling / dispersing step and the first extrusion washing step, the filtration membrane module of the filtration membrane device of the ultrapure water production and supply device is bypassed or dummy, and the filtration membrane module is installed before the sterilization step is performed. A cleaning method for an ultrapure water production and supply apparatus , wherein the sterilization step and the second extrusion cleaning step are performed while filtering the hydrogen peroxide cleaning liquid through the filtration module . The ultrapure water production and supply apparatus according to claim 1, wherein at least a part of the first extrusion cleaning step is performed without circulating water in a circulation system of the ultrapure water production and supply apparatus. Cleaning method. The ultrapure water production according to claim 1 or 2, wherein at least a part of the second extrusion cleaning step is performed without circulating water in a circulation system of the ultrapure water production and supply device. Cleaning method for feeding device.

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