JPH11139804A - Resistivity regulating device for ultrapure water and regulating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a convenient and compact device unnecessitating a controlling mechanism and for regulating the resistivity of ultrapure water and to provide a method therefor. SOLUTION: In an outside pouring type module in which ultrapure water is made to flow to a space part between the outside of a hollow fiber membrane and a housing and carbon dioxide is supplied to the inside of the hollow fiber membrane, a hollow fiber membrane module 1 provided in the housing in the state that the plural hollow fiber membranes are converged so that an overall permeation rate of the carbon dioxide from the inside of the hollow fiber membrane into the ultrapure water at the outside of the hollow fiber membrane becomes >=1×10<-7> and >=1×10<-4> (cm<2> (STP)/cm<2> .sec.cmHg) and a pressure controlling valve 2 for keeping a pressure of the carbon dioxide supplied to the membrane module constant are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for adjusting the specific resistance of ultrapure water used for cleaning water, particularly in the field of semiconductors and liquid crystals.

[0002]

2. Description of the Related Art In a semiconductor or liquid crystal manufacturing process, when cleaning a photomask substrate and a silicon wafer using ultrapure water (specific resistance ≧ 18 MΩ · cm), when cutting a wafer with a dicing machine, It is widely known that static electricity is generated due to the high specific resistance of ultrapure water, which causes dielectric breakdown or adsorption of fine particles, thereby significantly affecting the product yield of substrates. Therefore, in order to eliminate such an adverse effect, a method of mounting a magnesium mesh in the ultrapure water flow path to reduce the specific resistance of the ultrapure water is generally known.

A method of dissolving carbon dioxide gas in ultrapure water using a hydrophobic porous hollow fiber membrane module and lowering the specific resistance by carbonate ions generated by dissociation parallelism is known as a specific resistance of ultrapure water. Adjusting device (Japanese Patent Publication No. 5-21841), a method and an apparatus for adjusting the specific resistance of ultrapure water (Japanese Unexamined Patent Publication No.
No. 60082) has been proposed.

[0004] In the steps of cleaning and dicing silicon wafers, the flow rate of ultrapure water fluctuates greatly, and it is required that the resistivity does not fluctuate even if the flow rate fluctuates. In extreme cases, flow fluctuations in seconds may occur. As a method to control the specific resistance even when the flow rate of ultrapure water fluctuates,
A method of measuring the specific resistance after dissolving carbon dioxide gas and performing feedback control of the flow rate of carbon dioxide gas (3)
(Page 92) and a method of measuring the ultrapure water flow rate and performing feedforward control of the carbon dioxide gas flow rate by a mass flow controller (page 401).

[0005]

[Problems to be solved by the invention]
In the method of controlling the flow rate of carbon dioxide gas described in JP-A-21841 and the method of performing feedback control of the flow rate of carbon dioxide gas according to the method described in "Science of Ultrapure Water", it is impossible to follow a short-term flow rate fluctuation. In addition, the method of feedforward controlling the flow rate of carbon dioxide gas from the measured value of the flow rate of ultrapure water according to the method described in “Science of ultrapure water” requires an expensive microcomputer circuit and an expensive mass flow controller, and the controllability of the method is high. Is also not satisfactory. JP-A-7-6008
Japanese Patent Publication No. 2 does not include the idea of controlling the specific resistance to a constant value when the flow rate of ultrapure water fluctuates. Further, the fluctuation of the specific resistance value when the flow rate of the ultrapure water changes is inevitable only by setting the carbon dioxide gas pressure.

An object of the present invention is to solve all of these problems and to provide a simple and compact apparatus and method for adjusting the specific resistance of ultrapure water which does not require a control mechanism.

[0007]

The gist of the present invention is as follows.
It is. (1) In order to adjust the specific resistance of ultrapure water, a hollow fiber membrane module
The carbon dioxide gas is supplied to the ultrapure water using a
In an apparatus for producing ultrapure water with a resistance value, the outside of the hollow fiber membrane is
Flow ultrapure water into the space between the housings,
It is an external perfusion type that supplies carbon dioxide gas to the
Overall permeability of carbon dioxide from inside to ultrapure water outside the hollow fiber membrane
Overspeed is 1 × 10^-7More than 1 × 10^-FourBelow [cm^Three(ST
P) / cm^Two・ Sec ・ cmHg]
A plurality of thread membranes are disposed in the housing in a converged state.
Hollow fiber membrane module and charcoal supplied to the membrane module
Consists of a pressure regulating valve to keep the pressure of acid gas constant
Ultrapure water resistivity adjustment device. (2) Specific resistance value adjusted according to fluctuating consumption
In the specific resistance adjusting method for producing pure water, a hollow fiber membrane module is used.
A carbon dioxide gas is supplied to ultrapure water using a
The space between the outside of the hollow fiber membrane and the housing as joules
Flow ultrapure water into the section and supply carbon dioxide gas inside the hollow fiber membrane
External perfusion type, from the inside of the hollow fiber membrane to the outside of the hollow fiber membrane
The overall permeation rate of carbon dioxide into ultrapure water is 1 × 10^-7Less than
Top 1 × 10 ^-FourBelow [cm^Three(STP) / cm^Two・ Sec ・
cmHg], a plurality of hollow fiber membranes were converged.
The hollow fiber membrane module installed in the housing in the state
Pressure of the carbon dioxide gas supplied to the hollow fiber membrane module
A method for adjusting the specific resistance of ultrapure water by keeping it constant.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and the best state of the present invention are specifically shown in the following examples, and typical examples thereof are as follows.

The hollow fiber membrane module is made of poly-4-methylpentene-1 and has a carbon dioxide gas permeation rate of 1%.
0 × 10 ^-5 [cm ³ (STP) / cm ² · sec · cmH
g], a number of heterogeneous hollow fiber membranes having an inner diameter of 200 [μm] and an outer diameter of 250 [μm] are converged, and both ends of the yarn are solidified with a resin in a 200 to 700 cc inner volume housing made of clean vinyl chloride resin. An external perfusion type module having a hollow fiber membrane outer surface having a surface area of 0.5 [m ² ] and having a structure shown in FIG. 2 is incorporated in the apparatus shown in FIG.

As raw water, 18.2 [MΩ] at 25 ° C.
・ Cm] ultrapure water with a specific resistance of 8 [liter / m]
in. ], The resulting ultrapure water has a specific resistance of 0.1.
When the supply amount of carbon dioxide is adjusted so as to be 1 [MΩ · cm], carbon dioxide is supplied at a pressure of 0.5 [kg / cm ² · G] and a flow rate of 280 [cm ³ (STP) / min]. Appropriate. At this time, the overall transmission speed of carbon dioxide is 2.
4 × 10 ^-5 [cm ³ (STP) / cm ² · sec · cmH
g]. Ultrapure water flow rate of 2-8 [liter / mi]
n. ], The flow rate of the carbon dioxide gas also changes accordingly, and the fluctuation range of the specific resistance value of the ultrapure water obtained at that time is as follows:
It stays within ± 0.02 [MΩ · cm].

In order to arbitrarily obtain ultrapure water having a desired specific resistance at a desired flow rate, the flow rate of raw water is changed, the pressure of carbon dioxide gas is adjusted to change the flow rate of carbon dioxide gas, Various adjustments such as changing the total surface area or adjusting the internal water flow state by changing the membrane module structure are achieved by performing within the predetermined range of the overall transmission rate of carbon dioxide gas specified in the present invention. be able to.

Hereinafter, the present invention will be described in more detail. FIG. 1 shows an example of an apparatus according to the present invention. The present invention proposes a simple and compact apparatus and method for adding carbon dioxide to ultrapure water without a complicated control mechanism. In order to enhance the carbon dioxide gas addition efficiency, a further proposal is to arrange a hollow fiber membrane module in the apparatus and supply and add carbon dioxide gas to ultrapure water via the membrane.

The hollow fiber used in the present invention is not particularly limited in terms of material, structure and form as long as it has a high carbon dioxide gas permeation rate. The material of the membrane is preferably a material having high hydrophobicity.
For example, polyethylene resins, polypropylene resins, various fluororesins such as polytetrafluoroethylene, perfluoroalkoxy fluororesin, polyhexafluoropropylene, polybutene resins, silicone resins, poly (4-methylpentene-1) resins, etc. Materials are preferred. As the membrane structure, any of a so-called sandwich film in which a thin film of urethane or the like is sandwiched between layers such as a microporous film, a homogeneous film, a heterogeneous film, a composite film, and a polypropylene microporous film can be used.

The carbon dioxide gas permeation rate of the hollow fiber membrane is 1 × 10
^-6 (cm ³ (STP) / cm ² · sec · cmHg) or more. 1 × 10 ^-6 (cm ³ (STP)
/ Cm ² · sec · cmHg), the permeation rate of the carbon dioxide gas permeating through the hollow fiber membrane is low, and the specific resistance value does not reach the target specific resistance value or when the ultrapure water flow rate fluctuates. Fluctuates. Further, it is preferable that the carbon dioxide gas permeation rate is high, but at least 0.1 kg / cm ² at a gauge pressure.
As described above, it is preferable to keep the carbon dioxide gas to a level that does not cause bubbles even when the carbon dioxide gas is supplied. When carbon dioxide gas becomes bubbles, it becomes difficult to adjust the specific resistance value to a constant value.

In particular, a heterogeneous hollow fiber membrane made of a poly (4-methylpentene-1) -based resin is most preferable because of its excellent carbon dioxide gas permeability and high water vapor barrier property. The heterogeneous film is described in, for example, Japanese Patent Publication No. 2-38250, Japanese Patent Publication No. 2-54377, Japanese Patent Publication No. 4-15014, Japanese Patent Publication No. 4-50053, and Japanese Patent Application Laid-Open No. Hei 6-210.
No. 146, and the like.

Materials such as polyethylene resin, polypropylene resin and polyvinylidene fluoride resin have low gas permeability, and therefore have a microporous structure to be used for dissolving carbon dioxide gas. Compared to these membranes which have to pass gas, poly (4-
This heterogeneous membrane made of a methylpentene-1) -based resin has a sufficiently high gas permeability in itself and a sufficiently thin dense layer, and the entire membrane surface can contribute to carbon dioxide gas permeation. It is possible, and as a result, a substantial film area is increased, which is extremely preferable.

The poly (4-methylpentene)
1) An inhomogeneous membrane made of a system resin has a very small gas diameter and open area of communicating pores penetrating the membrane wall while having a high gas permeation performance. Therefore, the water vapor barrier is smaller than that of a microporous membrane of PP or PE. It has extremely excellent performance.

Regarding the housing in which the hollow fiber membrane is provided, any material can be used as long as it does not dissolve into the ultrapure water. Specific examples include polyethylene, polypropylene, polyolefins such as poly-4-methylpentene 1, fluorine such as polyvinylidene fluoride and polytetrafluoroethylene, polyetheretherketone, polyetherketone, polyethersulfone, polysulfone, and the like. Engineering plastics, or clean vinyl chloride-based materials used as piping materials for ultrapure water due to low elution.

In the hollow fiber membrane module structure, a plurality of hollow fiber membranes are converged and arranged in a housing, ultrapure water is flown into a space between the outside of the hollow fiber membrane and the housing, and the hollow fiber membrane is formed inside the hollow fiber membrane. It is an external perfusion type that supplies carbon dioxide gas, and the overall transmission rate of carbon dioxide gas from the inside of the hollow fiber membrane to the ultrapure water outside the hollow fiber membrane is 1 × 10 ⁻⁷ or more and 1 × 10 ⁻⁴ or less [cm ³ (S
TP) / cm ² · sec · cmHg], as long as a plurality of hollow fiber membranes are arranged in the housing in a state where they are converged.

The overall permeation speed is determined by flowing ultrapure water into the space between the outside of the hollow fiber membrane and the housing and permeating carbon dioxide gas from the inside to the outside of the hollow fiber so as to have a specific resistance value of a predetermined value. The carbon dioxide gas flow rate to the membrane area of the hollow fiber in the module,
It is determined by dividing by the partial pressure of carbon dioxide. That is, it indicates the efficiency of dissolving carbon dioxide gas in ultrapure water in the hollow fiber membrane module, and shows the permeation rate of carbon dioxide gas through the hollow fiber membrane and the dissolution rate of carbon dioxide gas in ultrapure water on the outer surface of the hollow fiber. ,
It is the total of the diffusion rate of carbon dioxide dissolved in ultrapure water in the module.

For example, ultrapure water having a specific resistance of 18 [MΩ · cm] is passed through a module having a membrane area of 5000 [cm ² ], and carbon dioxide gas is supplied at a pressure of 76 [cmHg] and 5 [cm ³ / sec].
By supplying, the specific resistance value is 0.1 [MΩ · cm]
, The overall transmission coefficient is 5 / (5000 × 7
6) = 1.31 × 10 ⁻⁵ .

FIGS. 2 and 3 show a typical module structure. In the module structure where the ultrapure water enters the module and exits from the outlet, the overall permeation speed increases in the module structure that effectively contacts the hollow fiber, and the ratio of ultrapure water that does not effectively contact the hollow fiber In a module structure with many components, the overall transmission speed is low. In general, the structure of FIG. 2 has a higher overall transmission speed than the structure of FIG. Even if the module structure is the same, the overall transmission speed tends to increase as the volume of the hollow fiber membrane occupying the internal volume of the module increases, and the overall transmission speed decreases as the volume of the hollow fiber membrane decreases.

The overall transmission speed is 1 × 10 ⁻⁴ [cm ³ (ST
P) / cm ² · sec · cmHg] or more, when the flow rate of ultrapure water fluctuates, the specific resistance value fluctuates even if the carbon dioxide gas pressure is kept constant. Further, when a hollow fiber membrane having a high carbon dioxide gas permeation rate is used, an appropriate specific resistance cannot be obtained unless it is supplied at a gauge pressure of 0 kg / cm ² or less. For that purpose, a complicated operation such as supplying a mixed gas obtained by diluting carbon dioxide gas with another gas or supplying carbon dioxide gas while evacuating is required, which is not preferable. The overall transmission speed is 1 × 10 ^-7 [cm ³ (STP) / cm ² · sec · cm
Hg] or less, the permeation amount of carbon dioxide gas is insufficient, and the specific resistance value does not reach the target value.

Regarding the carbon dioxide gas pressure regulating valve, any structure, material, and model can be used as long as it is filtered in advance so that contamination in the gas on the supply side (temporary side) does not adhere to the hollow fiber membrane. There is no need to specify it, and any material generally used in the semiconductor and liquid crystal fields may be used.

For example, there are pressure control valves (regulators) such as a pressure regulating valve, a bellows pressure valve, a pressure regulator, and a back pressure valve.

The pressure of the carbon dioxide gas is adjusted by a pressure adjusting valve so that the specific resistance value becomes a set value.

The mechanism of dissolving carbon dioxide gas in ultrapure water and the relationship between carbon dioxide concentration and specific resistance when carbon dioxide gas is directly dissolved in ultrapure water have been known in various documents.

Therefore, for the purpose of adjusting the specific resistance of ultrapure water,
Addition of a predetermined amount of carbon dioxide to ultrapure water via a hollow fiber membrane has also been proposed in a feedforward method, a feedback method, and the like described in Japanese Patent Publication No. 5-21841, "Science of Ultrapure Water". However, when the amount of ultrapure water fluctuates instantaneously, it is actually difficult to respond to it and follow and control a predetermined specific resistance value.

That is, the emphasis of the present invention is to provide an external perfusion type in which ultrapure water flows into the space between the outside of the hollow fiber membrane and the housing and carbon dioxide gas is supplied inside the hollow fiber membrane. The carbon dioxide gas permeates from the inside of the hollow fiber membrane into the ultrapure water outside the hollow fiber membrane, and the overall permeation rate of the carbon dioxide gas is 1 × 10 ⁻⁷ or more and 1 × 10 ⁻⁴ or less [cm ³ (STP ) /
cm ² · sec · cmHg] and the hollow fiber membrane module disposed in the housing with a plurality of hollow fiber membranes converged, and the pressure of carbon dioxide gas supplied to the membrane module is kept constant. Is to do.

Although it is not clear why the specific resistance value is kept constant even when the flow rate of the ultrapure water fluctuates only by keeping the pressure of the carbon dioxide gas constant, the following is presumed. That is, the overall transmission rate of carbon dioxide gas from the inside of the hollow fiber membrane to the ultrapure water outside the hollow fiber membrane is 1 × 10 ⁻⁴ [cm ³ (STP) / cm ^2].
[Sec · cmHg] or less, most of the ultrapure water flowing in the housing does not effectively contact the outer surface of the hollow fiber. Carbon dioxide is dissolved at a high concentration in ultrapure water in contact with the outer surface of the hollow fiber. The concentration becomes an equilibrium concentration with the pressure of the carbon dioxide gas, and does not change even if the flow rate of the ultrapure water changes. Therefore, a part of the ultrapure water having a constant carbon dioxide gas concentration is diluted at a constant ratio by the ultrapure water that has not effectively contacted the hollow fiber membrane surface in the module or downstream of the module. It is considered that even if the total flow rate of the ultrapure water supplied to the membrane module changes, the specific resistance does not change.

The degree to which the specific resistance should be controlled largely depends on the type of device in the semiconductor or liquid crystal field and the cleaning process used. In recent years, a specific resistance value of 0.1 [MΩ · cm] to 1 [MΩ · cm] is particularly desired in a wafer cleaning process and a dicing process in the field of semiconductors and liquid crystals. Appropriate values may be selected as the ratio of the volume of the hollow fiber membrane to the internal volume of the housing, the membrane area of the hollow fiber membrane, the volume of the module, and the carbon dioxide pressure according to the range of the specific resistance value to be set.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. However, the present invention is not limited thereto.

The specific resistance of ultrapure water is measured using a commercially available specific resistance meter (T
HONTON 200CR and COS CE-
480R). 25 [℃] as raw water
And ultrapure water having a specific resistance of 18.2 [MΩ · cm] at a flow rate of 2 to 8 [liter / min. ].

A carbon dioxide gas source of 7 [m ³ ] was prepared as a carbon dioxide gas source, and the pressure of the carbon dioxide gas to be supplied to the membrane module was adjusted by a two-stage pressure regulator and a pressure regulating valve.

Example 1 A hollow fiber membrane module was made of poly-4-methylpentene-1 and had a carbon dioxide gas transmission rate of 10 × 10 ⁻⁵ [cm ³ (STP) / cm ² · se].
c · cmHg], inner diameter 200 [μm], outer diameter 250 [μm]
m] of the heterogeneous membrane hollow fiber having an outer surface area of 0.5 [m
² ], and both ends of the yarn were solidified with a resin in a 640 cc internal volume housing made of clean vinyl chloride resin to obtain an external perfusion type module 1 having the structure shown in FIG.

FIG. 1 shows the flow of an apparatus incorporating the hollow fiber membrane module. Ultrapure water flow 8 [liter / mi]
n. ] At a pressure of 0.5 [kg / cm ² ·
G], the specific resistance value is 1 [MΩ · cm].
It became. At that time, the flow rate of carbon dioxide gas was 4 [cm ³ (ST
P) / min]. The overall transmission rate of carbon dioxide is
3.0 × 10 ^-7 [cm ³ (STP) / cm ² · sec · c
mHg]. Table 1 shows the results of the change in the specific resistance value by the module 1 when the flow rate of the ultrapure water was changed. Table 1 also shows the results when the carbon dioxide gas pressure was 1.0 [kg / cm ² · G].

Example 2 The hollow fiber membrane module was made of polypropylene and had a carbon dioxide gas permeation rate of 500.
× 10 ^-5 [cm ³ (STP) / cm ² · sec · cmH
g], an inner diameter of 300 [μm] and an outer diameter of 380 [μm] are converged such that the surface area of the outer surface of the hollow fiber membrane becomes 0.5 [m ² ], and an inner volume 320c made of polypropylene resin is formed.
The outer perfusion module 2 having the structure shown in FIG. 2 was obtained by solidifying both ends of the yarn with the resin in the housing c. Ultrapure water flow rate 8 [liter / min. ], The specific resistance was 0.1 [MΩ · cm] by supplying carbon dioxide at a pressure of 0.5 [kg / cm ² · G]. At this time, the flow rate of carbon dioxide gas is 280 [cm ³ (STP) / mi].
n]. The overall transmission rate of carbon dioxide is 2.4 × 1
0 ^-5 [cm ³ (STP) / cm ² · sec · cmHg]. Table 1 shows the results of the change in the specific resistance value by the module 2 when the flow rate of the ultrapure water was changed.

(Example 3) The same hollow fiber membrane as in Example 1 was used, and the hollow fiber membrane was made of polysulfone resin.
The outer perfusion type module 3 having the structure shown in FIG. 2 and having a surface area of the outer surface of the hollow fiber membrane of 1.0 [m ² ] was obtained by solidifying both ends of the fiber with a resin in the housing of FIG. Ultrapure water flow 8
[Liter / min. ] At a pressure of 1 [k
g / cm ² · G] so that the specific resistance value is 0.
It was 1 [MΩ · cm]. The carbon dioxide gas flow rate at that time is 2
It was 80 [cm ³ (STP) / min]. The overall transmission rate of carbon dioxide is 6.1 × 10 ^-6 [cm ³ (STP)
/ Cm ² · sec · cmHg]. Table 1 shows the results of the change in the specific resistance value by the module 3 when the flow rate of the ultrapure water was changed.

(Example 4) The same hollow fiber membrane as in Example 1 was used, and the hollow fiber membrane was converged so that the outer surface area became 1.0 [m2]. An external perfusion module 4 having the structure shown in FIG. 3 was obtained by solidifying one end of the yarn with a resin in the housing. Ultrapure water flow rate 8 [liter / min. ], The specific resistance was 1 [MΩ · cm] by supplying carbon dioxide gas at a pressure of 0.5 [kg / cm ² · G]. At that time, the flow rate of the carbon dioxide gas was 4 [cm ³ (STP) / min]. The overall transmission rate of carbon dioxide gas is 1.75 × 10
^-7 [cm ³ (STP) / cm ² · sec · cmHg]. Table 1 shows the results of the change in the specific resistance value by the module 4 when the flow rate of the ultrapure water was changed.

(Comparative Example 1) As a hollow fiber membrane module,
Made of poly-4-methylpentene-1
Overspeed is 10 × 10^-Five[Cm^Three(STP) / cm^Two・ Se
c · cmHg], inner diameter 200 [μm], outer diameter 250 [μm]
m], the surface area of the outer surface of the hollow fiber membrane
0.5 [m^Two] And clean chlorinated chloride.
Both yarns are housed in a 110 cc resin
The outer perfusion type of the structure of FIG. 2 is obtained by solidifying the ends with resin.
Module 5 was obtained. Ultrapure water flow 8 [liter / mi]
n. ] At a pressure of 0.05 kg / cm^Two
· G] to provide a specific resistance of 0.1 [MΩ
cm]. At this time, the flow rate of carbon dioxide gas is 280 [cm]
^Three(STP) / min]. Overall transmission of carbon dioxide
Speed is 2.5 × 10^-Four[Cm^Three(STP) / cm^Two・ S
ec · cmHg]. When the ultrapure water flow rate is changed
Table 1 shows the results of the specific resistance change by the module 5.

Comparative Example 2 The hollow fiber membrane module was made of poly-4-methylpentene-1 and had a carbon dioxide gas transmission rate of 10 × 10 ⁻⁵ [cm ³ (STP) / cm ² · se].
c · cmHg], inner diameter 200 [μm], outer diameter 250 [μm]
m] of the heterogeneous membrane hollow fiber is converged so that the surface area of the outer surface of the hollow fiber membrane becomes 0.1 [m ² ], and both ends of the fiber are resinized in a 3200 cc inner volume housing made of clean vinyl chloride resin. Thus, an external perfusion module 6 having the structure shown in FIG. 2 was obtained. Ultrapure water flow 8 [liter / m]
in. ], An attempt was made to adjust the carbon dioxide gas pressure so that the specific resistance value became 0.5 [MΩ · cm]. However, even when the carbon dioxide gas pressure was set to 1.5 [kg / cm ² · G], the specific resistance value was increased. Even when the density reached 2 [MΩ · cm], air bubbles were mixed in ultrapure water from the surface of the hollow fiber membrane. The overall transmission rate of carbon dioxide gas is 1 × 10 ⁻⁸ [cm ³ (STP) / cm ² · se]
c · cmHg] or less.

Comparative Example 3 The hollow fiber membrane module was made of poly-4-methylpentene-1 and had a carbon dioxide gas transmission rate of 10 × 10 ⁻⁵ [cm ³ (STP) / cm ² · se].
c · cmHg], inner diameter 200 [μm], outer diameter 250 [μm]
m] of the heterogeneous membrane hollow fiber is converged so that the surface area of the inner surface of the hollow fiber membrane becomes 0.1 [m ² ], and both ends of the fiber are solidified with a resin in a clean vinyl chloride resin housing. The module 7 of the internal perfusion type was obtained. Ultrapure water flow rate 8 [liter / min. ], The specific resistance is 0.1
The carbon dioxide gas pressure was adjusted to be [MΩ · cm], but the carbon dioxide gas pressure was adjusted to 0.05 [kgf / cm ² · cm].
G], the specific resistance value was 0.03 [MΩ · cm].

[0043]

[Table 1]

[0044]

According to the present invention as described above, carbon dioxide gas is added and dissolved in ultrapure water having high specific resistance using a hollow fiber membrane for gas-liquid contact, and the specific resistance value is lowered. In the production of ultrapure water adjusted to a specific level, even if there is a sudden change in the consumption on the consumption side of the ultrapure water with adjusted resistivity, the ultrapure water with a specific range of specific resistance The method and the apparatus capable of stably supplying the membrane module have an external perfusion type, and the total permeation rate of the membrane in the housing, which can be easily calculated by using the overall permeation rate of carbon dioxide in a specific numerical range as an index, This is achieved by the simple means of setting the carbon dioxide pressure and keeping it constant with the pressure regulating valve, and the accompanying very simplified construction of the components. This eliminates the need for an expensive special control mechanism, and makes it possible to obtain a compact, low-cost device that is easy to handle and has high reliability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a specific resistance adjusting device for ultrapure water for specific resistance adjustment according to the present invention.

FIG. 2 is a schematic view of a first type of hollow fiber membrane module according to the present invention.

FIG. 3 is a schematic view of a second type of hollow fiber membrane module according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane module 2 Carbon dioxide gas pressure control valve 3 Pressure gauge 4 Housing 5 Hollow fiber 6 Adhesive seal resin

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/304 648 H01L 21/304 648G

Claims (2)

[Claims] In order to adjust the specific resistance of ultrapure water, a hollow fiber membrane module is used to supply carbon dioxide gas to ultrapure water to produce ultrapure water having a desired specific resistance. Ultrapure water flows into the space between the outside of the fiber membrane and the housing, and carbon dioxide gas is supplied to the inside of the hollow fiber membrane. The overall permeation rate of carbon dioxide gas to 1 × 10 ⁻⁷ or more and 1 × 10 ⁻⁴ or less [cm
³ (STP) / cm ² · sec · cmHg] and a hollow fiber membrane module disposed in the housing in a state where a plurality of hollow fiber membranes are converged, and a pressure of carbon dioxide gas supplied to the membrane module. Resistance adjusting device for ultrapure water, comprising a pressure regulating valve for keeping the pressure constant. 2. A specific resistance adjusting method for producing ultrapure water having a specific resistance value adjusted according to a fluctuating consumption amount, wherein carbon dioxide gas is supplied to ultrapure water using a hollow fiber membrane module, As a membrane module, it is an external perfusion type in which ultrapure water flows in the space between the outside of the hollow fiber membrane and the housing, and carbon dioxide gas is supplied to the inside of the hollow fiber membrane. The overall permeation rate of carbon dioxide into ultrapure water is 1 ×
10 ^-7 or more and 1 × 10 ^-4 or less [cm ³ (STP) / cm ^2.
using a hollow fiber membrane module disposed in a housing in a state where a plurality of hollow fiber membranes are converged so that the pressure of carbon dioxide gas supplied to the hollow fiber membrane module is kept constant. A method for adjusting the specific resistance of ultrapure water.