WO2020031616A1

WO2020031616A1 - Method for removing microparticles in water

Info

Publication number: WO2020031616A1
Application number: PCT/JP2019/027682
Authority: WO
Inventors: 侑藤村; 小川　祐一; 田中　洋一; 孝博川勝; 真幸金田; 光明松本
Original assignee: 栗田工業株式会社; 旭化成株式会社
Priority date: 2018-08-10
Filing date: 2019-07-12
Publication date: 2020-02-13
Also published as: TW202017643A; JP7210931B2; JP2020025922A

Abstract

With respect to an ultrapure water production process where microparticles in water are removed using an NF membrane or UF membrane having at least one functional group of any of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group, the purpose of the present invention is to suppress the influence of the functional group introduced to the MF membrane or UF membrane and produce high-quality microparticle-free treated water suitable as ultrapure water for use in steps of producing and washing an electronic component. Before removal of microparticles, the MF membrane or UF membrane having at least one functional group of any of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group is washed with an alkaline agent having a pH of 9 or more and then used to remove microparticles.

Description

Removal method of fine particles in water

The present invention relates to a method for removing fine particles in water. Specifically, the present invention relates to a method for producing fine particles in water by using at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group in an ultrapure water production process or the like. In the removal by the microfiltration membrane or ultrafiltration membrane, the effect of the functional group introduced into the microfiltration membrane or ultrafiltration membrane is suppressed, and the high-purity water suitable for the ultrapure water used in the electronic component manufacturing process and the cleaning process The present invention relates to a method for producing water treated for removing particulates having properties.

(1) A system for producing and supplying ultrapure water used in a semiconductor manufacturing process or the like is generally configured as shown in FIG. An ultrafiltration membrane (UF membrane) device 17 for removing fine particles is installed at the end of the subsystem 3 to remove fine particles of nanometer size. A mini-subsystem is installed as a point of use polisher just before the washing machine for cleaning semiconductor and electronic materials, and a UF membrane device for removing particles is installed at the last stage. It has been studied to install a UF film of the type described above and to highly remove fine particles having a smaller size.

水中 With the development of the semiconductor manufacturing process, the control of fine particles in water has become increasingly strict. For example, according to the International Semiconductor Technology Roadmap for Semiconductors (ITRS), in 2019, the guaranteed value of particle diameter> 11.9 nm <1,000 particles / L (management value <100 particles / L) Is required.

(4) The following proposals have been made as a technique for highly removing impurities such as fine particles in water to increase the purity in an ultrapure water production apparatus.

In Patent Document 1, a membrane separation means is provided in any of a pretreatment device, a primary water purification device, a secondary water purification device (subsystem), or a recovery device that constitutes an ultrapure water supply device, and an amine elution is provided in a subsequent stage. It is described that a reverse osmosis membrane which has been subjected to a reduction treatment is arranged. Although it is possible to remove fine particles with a reverse osmosis membrane, it is not preferable to provide a reverse osmosis membrane for the following reasons.
In order to operate the reverse osmosis membrane, the pressure must be increased, and the amount of permeated water is as small as about 1 m ³ / m ² / day at a pressure of 0.75 MPa. In the current system using the UF membrane, the water volume is 7 m ³ / m ² / day, which is 50 times or more at a pressure of 0.1 MPa. A film area is required. Since the reverse osmosis membrane drives the pressurizing pump, there is a risk that new fine particles and metals are generated.

Patent Document 2 describes that a functional material having an anionic functional group or a reverse osmosis membrane is disposed downstream of a UF membrane in an ultrapure water line. The purpose of this functional material or reverse osmosis membrane having an anionic functional group is to reduce amines and is not suitable for removing fine particles having a particle diameter of 10 nm or less in the present invention. It is not preferable to dispose a reverse osmosis membrane as in Patent Document 1 described above.

Patent Document 3 also describes that a reverse osmosis membrane device is provided before a UF membrane device in the last stage in a subsystem, but has the same problem as Patent Document 1.

Patent Document 4 describes removing a particle by incorporating a pre-filter in a membrane module used in an ultrapure water production line. Patent Literature 4 aims at removing particles having a particle diameter of 0.01 mm or more, and cannot remove fine particles having a particle diameter of 10 nm or less in the present invention.

Patent Literature 5 discloses a membrane having a MF membrane modified with an ion exchange group after filtering treated water of an electrodeionization apparatus with a UF membrane filtration apparatus having a filtration membrane not modified with an ion exchange group. The treatment with a filtration device is described. Patent Document 5 only exemplifies a cation exchange group such as a sulfonic acid group and an iminodiacetic acid group as the ion exchange group. The definition of the ion-exchange group includes an anion-exchange group, but there is no description about the type or the object to be removed.

Patent Document 6 describes that an anion adsorption membrane device is disposed at a stage subsequent to a UF membrane device in a subsystem, and reports an experimental result in which silica is to be removed. Patent Document 6 does not describe the type of anion exchange group or the size of fine particles. It is generally known that a strong anion exchange group is required to remove ionic silica (Diaion 1 ion exchange resin / synthetic adsorbent manual, Mitsubishi Chemical Corporation, p15). It is considered that the membrane having a strong anion exchange group is also used in Reference 6.

Patent Literatures 7 and 8 describe polyketone membranes modified with various functional groups as separator membranes for capacitors and batteries, and Patent Literature 8 also describes applications as filter media for water treatment. . None of the publications disclose the elution of the functional group introduced into the membrane.

Patent Literature 9 includes one or more functional groups selected from the group consisting of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium salt, and has an anion exchange capacity of 0. Polyketone porous membranes with a content of from 01 to 10 meq / g are described. Patent Document 9 states that this polyketone porous membrane can efficiently remove impurities such as fine particles, gels, and viruses in manufacturing processes of semiconductor / electronic parts manufacturing, biopharmaceuticals, chemicals, and the food industry. Is described. There is also a description suggesting that it is possible to remove 10-nm fine particles and anionic particles having a diameter smaller than the pore diameter of the porous membrane.

However, Patent Document 9 does not describe that this polyketone porous membrane is applied to an ultrapure water production process. There is no suggestion regarding elution of the functional groups introduced into the membrane.

Patent Document 10 discloses an underwater particulate removal device capable of highly removing ultra-fine particulates having a particle diameter of 50 nm or less, particularly 10 nm or less in water in a subsystem or a water supply path before a point of use in an ultrapure water production / supply system. A microfiltration (MF) membrane or an ultrafiltration (UF) membrane having a weak cationic functional group, specifically, a membrane filtration means having an MF membrane or a UF membrane in which a weak cationic functional group is introduced into a polyketone membrane. An apparatus for removing fine particles in water and a system for producing and supplying ultrapure water provided with the apparatus for removing fine particles in water are described.

Patent Document 10 does not disclose elution of weakly cationic functional groups such as tertiary amino groups introduced into the membrane and conditioning for suppressing elution.

Japanese Patent No. 3906684 Japanese Patent No. 4508469 JP-A-5-138167 Japanese Patent No. 3059238 JP 2004-283710 A JP-A-10-216721 JP 2009-286820 A JP 2013-76024 A JP 2014-173013 A JP 2016-155052 A

As described above, conventionally, when a porous membrane into which a functional group is introduced as described in Patent Documents 9 and 10 is applied to an ultrapure water production process, water for removing fine particles capable of obtaining the functional group introduced into the membrane is used. There is no recognition of the effect on the particle size, and no method of conditioning such a fine particle removal film has been studied.

According to the study of the present inventors, when a fine particle removal treatment is performed using a porous membrane into which a cationic or weak cationic functional group is introduced, the functional group introduced into the membrane is eluted into water to remove the fine particles. It was found to be contained in the water. For example, if the water for removing fine particles is used in a semiconductor wafer manufacturing or cleaning process, the eluted functional groups cause problems such as surface roughness of the wafer.

The present invention relates to an NF film having at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group in an ultrapure water production process or the like. Alternatively, in the removal by the UF film, the effect of the functional group introduced into the MF film or the UF film is suppressed, and high-quality fine particle removal treatment water suitable as ultrapure water used in the electronic component manufacturing process and the cleaning process is manufactured. An object of the present invention is to provide a method of removing fine particles in water.

The present inventors have developed an MF film or a UF film having at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group used for removing fine particles. Prior to this, it was found that by washing with an alkaline agent having a pH of 9 or more, elution of functional groups from the MF film or UF film can be suppressed, and the influence of the eluted functional groups can be reduced.

(4) The gist of the present invention is as follows.

[1] Fine particles in water are removed by a microfiltration membrane or an ultrafiltration membrane having at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. A method for removing fine particles in water, comprising washing the microfiltration membrane or the ultrafiltration membrane with an alkaline agent having a pH of 9 or more prior to the treatment for removing fine particles in water.

[2] The method for removing fine particles in water according to [1], wherein the alkaline agent is an alkaline agent having a pH of 11 or more.

[3] The method for removing fine particles in water according to [1] or [2], wherein the alkali agent is an alkali agent containing no alkali metal.

[4] The method for removing fine particles in water according to any one of [1] to [3], wherein the alkaline agent contains tetramethylammonium hydroxide.

[5] The method according to any one of [1] to [4], wherein the microfiltration membrane or the ultrafiltration membrane is washed with carbonated water having a pH of 3 to 6 after the washing with the alkaline agent. Removal method.

[6] The method for removing fine particles in water according to any one of [1] to [5], which is a method for removing fine particles in water in the ultrapure water production process.

According to the present invention, in an ultrapure water production process or the like, fine particles in water have at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. Prior to the removal by the MF film or UF film, these films are washed with an alkaline agent having a pH of 9 or more to suppress the elution of the introduced functional groups and reduce the influence of the functional groups before the fine particle removal treatment. Can be. For example, when cleaning Si wafers using the water for removing fine particles obtained by the present invention, the surface roughness of the wafer due to the elution component of the water for removing fine particles is suppressed, and a high quality product is obtained. be able to.

(4) After the cleaning with the alkaline agent according to the present invention, by washing with carbonated water, the residual of the alkaline agent can be prevented, and problems such as surface roughness of the wafer due to the residual alkaline agent can be further reduced.

FIG. 1 is a system diagram showing an example of the ultrapure water production / supply system.

Hereinafter, embodiments of the present invention will be described in detail.

The method for removing fine particles in water according to the present invention includes, in an ultrapure water production process or the like, fine particles in water, wherein at least one of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group is used. In removing the MF film or the UF film having a functional group, the MF film or the UF film having the functional group is washed with an alkaline agent having a pH of 9 or more prior to the fine particle removal treatment.

アルカリ The alkaline agent used for cleaning must have a pH of 9 or more. If the pH of the alkaline agent used for washing is less than 9, the object of the present invention cannot be achieved. The alkaline agent used for cleaning preferably has a pH of 10 or more, and more preferably has a pH of 11 to 13, in order to obtain a better cleaning effect.

As the alkali agent, an inorganic alkali agent or an organic alkali agent may be used. Examples thereof include hydroxides of alkali metals such as sodium hydroxide (NaOH) and potassium hydroxide (KOH), ammonia, and tetraalkylammonium hydroxide (TAAH) such as tetramethylammonium hydroxide (TMAH). It is not limited to these. The alkali agents may be used alone or in a combination of two or more.

では From the viewpoint of the effect of suppressing the dissolution of the functional group by the alkali agent, a hydroxide of an alkali metal such as NaOH is preferable. However, with an alkaline agent containing a metal component, if this remains on the film surface after cleaning, there is a concern that the residual metal component may have a new effect. In the case of TAAH such as TMAH, there is no influence by the metal component. In a field that dislikes metal components, it is preferable to use TAAH such as TMAH.

洗浄 The cleaning method using an alkali agent is not particularly limited, but immersion cleaning in which a film to be cleaned is immersed in an aqueous solution of an alkali agent is preferable. The immersion cleaning time is preferably long in order to obtain a good cleaning effect, and is usually preferably 2 hours or more, for example, about 2 to 24 hours.

膜 It is preferable that the membrane after the cleaning with the alkaline agent is rinsed with ultrapure water. The rinsing with ultrapure water is preferably performed by overflow. The rinsing time is preferably 30 minutes or more, for example, about 30 minutes to 24 hours.

The washing with an alkali agent and the rinsing with ultrapure water alone can sufficiently obtain the effect of suppressing the elution of the functional group. However, as described above, in order to prevent the alkali agent used for washing from remaining on the film surface, it is necessary to further use carbonated water. It is preferable to wash with.

炭酸 The pH of carbonated water used for washing with carbonated water is preferably 3 to 6, particularly 4 to 6, and particularly preferably 4 to 5. If the pH of the carbonated water is too high, the effect of removing the residual alkali agent by the carbonated water cannot be sufficiently obtained.

洗浄 Washing with carbonated water is preferably performed by overflow, similarly to rinsing with ultrapure water. The washing time with carbonated water is preferably longer in terms of the washing effect, and is preferably at least 1 hour, particularly preferably about 1 to 24 hours.

洗浄 After washing with carbonated water, the washed film can be used as it is for the removal treatment of fine particles, but may be further rinsed with ultrapure water as needed.

微粒子 Remove fine particles in water using a fine particle removing membrane which has been washed and conditioned with an alkaline agent or an alkaline agent and carbonated water before use.

The film for removing fine particles used in the present invention is an MF film or a UF film having at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. As such a film for removing fine particles, a porous film described in Patent Document 9 or Patent Document 10 described above can be used.

Since the fine particles in water are negatively charged, an MF film or a UF film having at least one cationic functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group By using, fine particles in water can be adsorbed and captured by the cationic functional groups of the membrane, and can be efficiently removed.

The material of the MF film or the UF film is not particularly limited as long as it has the above-mentioned cationic functional group. As the MF film or the UF film, a polyketone film, a cellulose mixed ester film, a polyethylene film, a polysulfone film, a polyethersulfone film, a polyvinylidene fluoride film, a polytetrafluoroethylene film, or the like can be used. A polyketone film is preferred because it has a large surface aperture ratio, can expect a high flux even at low pressure, and can easily introduce a weak cationic functional group into the MF film or UF film by chemical modification.
The polyketone membrane is a polyketone porous membrane containing 10 to 100% by mass of a polyketone, which is a copolymer of carbon monoxide and one or more olefins, and is a known method (for example, JP-A-2013-76024, International Publication). No. 2013/035747).

Ｍ The MF film or UF film having a cationic functional group captures and removes fine particles in water with an electric adsorption ability. The pore size of the MF membrane or the UF membrane may be larger than the fine particles to be removed. However, if the pore size is excessively large, the efficiency of removing fine particles is poor. Absent. The MF film preferably has a pore size of about 0.05 to 0.2 μm. The UF membrane preferably has a molecular weight cut-off of about 5,000 to 1,000,000.

The shape of the MF membrane or the UF membrane is not particularly limited, and a hollow fiber membrane, a flat membrane, or the like generally used in the field of producing ultrapure water can be employed.

The cationic functional group may be directly introduced into the polyketone film or the like constituting the MF film or UF film by chemical modification. The cationic functional group may be a compound having a cationic functional group, an ion exchange resin, or the like provided on the MF membrane or the UF membrane by being supported on the MF membrane or the UF membrane.

As a method for introducing a cationic functional group into the MF film or the UF film, the methods described in Patent Documents 9 and 10 described above can be adopted.

Washing with an alkali agent or an alkali agent and carbonated water in the method for removing fine particles in water according to the present invention is a system for producing ultrapure water from a primary pure water system in an ultrapure water production / supply system, and in particular, for the subsystem. It is suitably applied to the MF membrane or UF membrane device for removing fine particles at the last stage.
The method for removing underwater particulates according to the present invention comprises a MF membrane for removing particulates or a UF membrane device provided in a water supply system for feeding ultrapure water from a subsystem to a point of use or an MF membrane as a final particulate removing device at a point of use. Alternatively, it is suitably applied to a UF membrane device.

According to the present invention, using a MF membrane or a UF membrane device having a cationic functional group to highly remove fine particles having a particle diameter of 50 nm or less in water, particularly 10 nm or less, and suppressing a problem due to elution of the functional group, It is possible to obtain high-quality fine particle removal treatment water.

The present invention will be described more specifically with reference to the following examples.

In the following evaluation, a cationic polyketone porous membrane (membrane size: about 14 cm ² (hollow fiber state)) and a functional group: mainly a tertiary amino group described in Patent Document 9 (Japanese Patent Application Laid-Open No. 2014-173013) were used. Amino group, film material: polyketone, pore size: 0.14 μm) were used as a sample film.

[Example 1]
The following steps (1) to (7) were performed to evaluate the elution of the functional group from the sample membrane. A NaOH aqueous solution (pH 12) was used as the alkaline agent.

Step (1): The sample film was immersed in 200 mL of an aqueous NaOH solution (pH 12) for 2 hours.
Step (2): The sample film of (1) was overflow rinsed with 1 L / min of ultrapure water for 30 minutes.
Step (3): The sample film of (2) was immersed in 200 mL of ultrapure water for 18 hours.
Step (4): 10 mL of the immersion liquid of step (3) was applied onto a Si wafer.
Step (5): The Si wafer to which the immersion liquid was applied was allowed to stand for 1 hour.
Step (6): The Si wafer of (5) was dried with a spin dryer at 1500 rpm for 30 seconds.
Step (7): FT-IR analysis was performed on the dried Si wafer surface.

Evaluation of the roughness of the Si wafer surface by FT-IR analysis is based on the ratio of the peak intensity of Si—H to the peak of Si—H ₃ (index K = peak intensity of Si—H / peak of Si—H ₃ ). Was performed. It is considered that the larger the value of K, the rougher the surface of the Si wafer.

[Comparative Example 1]
FT-IR analysis of the surface of the Si wafer was performed in the same manner as in Example 1 except that the alkali cleaning and the rinsing with ultrapure water in the steps (1) and (2) were not performed.

[Comparative Example 2]
Then, 10 mL of ultrapure water was applied on the Si wafer, and then steps (5) to (7) of Example 1 were performed (blank).

Table 1 shows the FT-IR analysis results of the Si wafer surfaces of Example 1 and Comparative Examples 1 and 2.

[Example 2]
The following steps (1) to (8) were performed to evaluate the elution of the functional group from the sample membrane. A TMAH aqueous solution (pH 12) was used as the alkaline agent. Carbonated water having a pH of 4.65 was used.

Step (1): The sample film was immersed in 200 mL of a TMAH aqueous solution (pH 12) for 2 hours.
Step (2): The sample film of (1) was overflow rinsed with 1 L / min of ultrapure water for 30 minutes.
Step (3): The sample membrane of (2) was overflow-washed with 1 L / min of carbonated water (pH 4.65) for 1 hour.
Step (4): The sample film of (3) was immersed in 200 mL of ultrapure water for 18 hours.
Step (5): 10 mL of the immersion liquid of step (4) was applied on a Si wafer.
Step (6): The Si wafer to which the immersion liquid was applied was allowed to stand for 1 hour.
Step (7): The Si wafer of (6) was dried with a spin dryer at 1500 rpm for 30 seconds.
Step (8): After drying, the surface of the Si wafer was subjected to FT-IR analysis.

[Example 3]
In Example 2, FT-IR analysis of the surface of the Si wafer was performed in the same manner as in step (3) except that overflow rinsing was performed using ultrapure water instead of carbonated water.

Table 2 shows the results of Examples 2 and 3 together with the results of Comparative Example 1.

[Results and Discussion]
From Example 1, it can be seen that by performing alkali cleaning, elution of functional groups from the porous film can be suppressed, and roughness of the Si wafer surface can be suppressed.
From Example 3, it can be seen that by performing TMAH cleaning, the peak intensity ratio can be made smaller than in Comparative Example 1, and the roughness of the Si wafer surface can be suppressed.
Example 2 shows that by performing the washing with carbonated water after the alkali washing, TMAH used as the alkali agent can be efficiently washed and removed.

洗浄 When washed with NaOH, a large amount of Na remains on the membrane surface, and may not be applied as a filter for ultrapure water. Since TMAH does not contain a metal component, it can be used in such a case.

Although the invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2018-151720 filed on August 10, 2018, which is incorporated by reference in its entirety.

Reference Signs List 1 Pretreatment system 2 Primary pure water system 3 Subsystem 4 Use point 17 UF membrane device

Claims

This is a method for removing fine particles in water using a microfiltration membrane or an ultrafiltration membrane having at least one functional group of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. hand,
A method for removing fine particles in water, comprising washing the microfiltration membrane or ultrafiltration membrane with an alkaline agent having a pH of 9 or more prior to the treatment for removing fine particles in water.
The method according to claim 1, wherein the alkaline agent is an alkaline agent having a pH of 11 or more.
(3) The method for removing fine particles in water according to (1) or (2), wherein the alkali agent is an alkali agent containing no alkali metal.
The method according to any one of claims 1 to 3, wherein the alkaline agent includes tetramethylammonium hydroxide.
The method according to any one of claims 1 to 4, wherein the microfiltration membrane or the ultrafiltration membrane is washed with carbonated water having a pH of 3 to 6 after the washing with the alkaline agent.
The method for removing fine particles in water according to any one of claims 1 to 5, wherein the method is a method for removing fine particles in water in the ultrapure water production process.