JP4645827B2 - Carbon dioxide-dissolved water evaluation method and carbon dioxide-dissolved water sample water sampling device - Google Patents

Description

  The present invention relates to a method for evaluating carbon dioxide-dissolved water and a water collection device for a sample of carbon dioxide-dissolved water. More specifically, the present invention relates to a carbon dioxide-dissolved water evaluation method and a carbon dioxide-dissolved water sample capable of accurately quantifying the chlorine ion concentration in carbon dioxide-dissolved water used in wet cleaning processes such as electronic materials. It relates to a water sampling device.

  The demand level for the quality of ultrapure water is becoming stricter as ultra-fine processing and higher performance in the electronic industry field, and it is required to quantitate impurities such as various ions, metals, and organic carbon (TOC). Yes. Recently, not only the quality of ultrapure water but also gas dissolved water prepared by dissolving a specific gas in ultrapure water is required to have a water quality equivalent to that of ultrapure water. It has been found that water having various functions by dissolving a specific gas in ultrapure water used for rinsing in the wet cleaning process is effective for cleaning. Ultrapure water used in rinsing tends to be charged due to its low electrical conductivity, and often causes electrostatic breakdown to the object to be cleaned. Therefore, in a semiconductor manufacturing factory or the like, in order not to cause electrostatic breakdown, a method is often used in which carbon dioxide gas is dissolved in ultrapure water to increase electrical conductivity and suppress charging.

  Even if the ultrapure water that is the raw water for dissolving the carbon dioxide gas is of high purity, the ultrapure water or the carbon dioxide dissolved water is in contact with the carbon dioxide dissolving device, the carbon dioxide dissolved water transfer pipe, etc. It cannot be said that there is no possibility that impurities eluted from the contact member and a very small amount of impurities contained in the supplied carbon dioxide dissolved in the carbon dioxide-dissolved water, and water quality analysis is required for the carbon dioxide-dissolved water. For example, chlorine ions are one of the ions that should be removed as much as possible, and measurement of the chlorine ion concentration below the ng / L level is required.

  In recent years, ultrapure water quality analysis technology has progressed and it is possible to analyze trace amounts of chlorine ions. However, water quality analysis of gas-dissolved water has not been sufficiently studied, and ultrapure water quality analysis technology has not been developed. Even if diverted to analysis of gas-dissolved water, it cannot always be said that analysis can be performed accurately. Microanalysis of chlorine ions in water is usually performed by ion chromatography. In ion chromatography, sample water is passed through a concentration column packed with an ion exchange resin to adsorb ions, and then the eluent is passed through the concentration column. Pass through and constantly measure the electrical conductivity of the liquid flowing out from the separation column, create a chromatogram using the difference in distribution coefficient depending on the ion species, and the detection peak is displayed in the retention time zone according to the ion species . The ions are quantified based on the area of the detected peak. However, even if such an ion determination method is used for the determination of chlorine ions in carbon dioxide-dissolved water, it is difficult to accurately measure the extremely small concentration of chlorine ions because carbon dioxide is an interfering substance for the determination of chlorine ions. there were.

  The present invention provides a method for evaluating carbon dioxide-dissolved water that can accurately quantify the trace amount of chlorine ion concentration in carbon dioxide-dissolved water used in a wet cleaning process for electronic materials and the like, and collecting a sample of carbon dioxide-dissolved water. It was made for the purpose of providing a water device.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have determined that the measured value of the chlorine ion concentration is a bicarbonate ion and / or carbonate ion (hereinafter referred to as “( It changes according to the concentration of (heavy) carbonate ion.), And if the concentration of (heavy) carbonate ion is high, the measured value of chlorine ion concentration is also high, and the carbon dioxide gas in the carbon dioxide-dissolved water is removed by deaeration. Later, by quantifying chlorine ions by ion chromatography, it was found that even a very small amount of chlorine ions could be accurately quantified, and the present invention was completed based on this finding.

That is, the present invention
(1) Carbon dioxide-dissolved water in which carbon dioxide-dissolved water prepared by dissolving carbon dioxide in ultrapure water is degassed and then degassed to the extent of carbon dioxide degassing. In the method of determining by measuring the electrical conductivity of the carbon dioxide gas, after degassing the carbon dioxide dissolved water until the electrical conductivity of the carbon dioxide dissolved water becomes 0.1 mS / m or less , An evaluation method for carbon dioxide-dissolved water used in a wet cleaning process of an electronic material characterized by enhancing the quantitative accuracy of a very small amount of chlorine ions in carbon dioxide-dissolved water by a method of performing quantification by ion chromatography, and
( 2 ) Carbon dioxide dissolved water sample apparatus used in the evaluation method according to (1), wherein the carbon dioxide dissolved water is deaerated , and the carbon dioxide dissolved water deaerated in the deaerator An electric conductivity meter for measuring electric conductivity or an electric conductivity meter , and a water sampling device for collecting a carbon dioxide-dissolved water sample, which is filled with degassed carbon dioxide-dissolved water;
Is to provide.

  The method for evaluating carbon dioxide-dissolved water according to the present invention enables accurate determination of a very small amount of chlorine ions in carbon dioxide-dissolved water by ion chromatography. Can be managed with. By using the water sampling device for carbon dioxide-dissolved water sample of the present invention, even if the analyzer is located away from the line where carbon dioxide-dissolved water is used, the sample water is dissolved without causing quality fluctuation in the sample water. It is possible to accurately measure the chlorine ion concentration in water.

  In the evaluation method for carbon dioxide-dissolved water of the present invention, after degassing the carbon dioxide-dissolved water prepared by dissolving carbon dioxide in ultrapure water, the chlorine ions in the carbon dioxide-dissolved water are quantified. According to the method of the present invention, the analysis accuracy of chlorine ion concentration in carbon dioxide-dissolved water used as cleaning water in electronic component cleaning processes, etc. is improved, process management is facilitated, the occurrence of defective products is prevented, and product quality is improved. Can be increased. Although the chlorine ion concentration in ultrapure water used as raw water for carbon dioxide dissolved water is extremely low, the production process of carbon dioxide dissolved water for dissolving carbon dioxide gas in ultrapure water, the subsequent transfer process of carbon dioxide dissolved water, etc. In this case, chlorine ions may be mixed into the carbon dioxide-dissolved water, and defective products are produced when electronic parts are washed with carbon dioxide-dissolved water having a high chlorine ion concentration. By evaluating the carbon dioxide-dissolved water using the method of the present invention, it is confirmed that the chlorine ion concentration in the carbon dioxide-dissolved water is not more than a predetermined control level. Parts can be cleaned.

  In the method of the present invention, the degassing means for carbon dioxide-dissolved water is not particularly limited as long as it can remove carbon dioxide in water. For example, vacuum degassing, membrane degassing, nitrogen degassing, heat degassing, A combination of these can be mentioned. The degree of degassing can be controlled by adjusting the degree of vacuum, the amount of degassed water, the amount of inert gas such as nitrogen gas, the gas-liquid contact area, etc. You can also

By degassing the carbon dioxide-dissolved water, the amount of (heavy) carbonate ions dissolved in the carbon dioxide-dissolved water to be analyzed can be reduced, and a trace amount of chlorine ions can be accurately quantified. When carbon dioxide gas dissolves in water, carbonic acid H ₂ CO ₃ is generated, and further, bicarbonate ions HCO ₃ ⁻ and carbonate ions CO ₃ ²⁻ are generated by dissociation of carbonic acid. (Heavy) carbonate ions often act as interfering substances in the analysis of chloride ions. For example, in ion chromatography, the peak of (heavy) carbonate ions generated by dissolution of carbon dioxide in ultrapure water and the peak of chloride ions overlap or are close to each other. It is estimated that the base level of the ion peak is pushed up and the measured value is higher than the true chlorine ion concentration. Alternatively, depending on the carbonic acid concentration or (heavy) carbonate ion concentration in the sample water, chloride ions may be eluted from analytical devices such as columns, packing materials, piping, pumps, etc., and the measured value of the chlorine ion concentration may be increased. Conceivable.

  By removing carbonic acid from the carbon dioxide-dissolved water by degassing, the concentration of carbonic acid in the water is lowered, and the concentration of (bi) carbonate ions in equilibrium with carbonic acid is also lowered. By reducing the concentration of (bi) carbonate ions that act as an interfering substance for the determination of chloride ions, it is possible to increase the accuracy of measurement of extremely small amounts of chloride ions.

  In the method of the present invention, the degree of degassing of the carbon dioxide-dissolved water can be determined by the electrical conductivity of the degassed carbon dioxide-dissolved water. Carbon dioxide-dissolved water is prepared by dissolving carbon dioxide in ultrapure water. Basically, except for a very small amount of impurities, dissolved ionic substances are generated by dissolving carbon dioxide. Only (heavy) carbonate ions. Thus, the electrical conductivity reflects the concentration of (bi) carbonate ions in the water and can reflect the degree of degassing.

  In the method of the present invention, the method for quantifying chlorine ions is not particularly limited, and examples thereof include a silver nitrate titration method, an ion electrode method, and ion chromatography. Among these, ion chromatography suitable for quantification of a very small amount of chlorine ions can be suitably used. In the method of the present invention, since (bi) carbonate ions, which are substances that interfere with the determination of chlorine ions, are removed to a low concentration by degassing, a very small amount of chlorine ions can be accurately determined.

  In the method of the present invention, the electric conductivity of the carbon dioxide-dissolved water after the deaeration treatment is preferably 0.1 mS / m or less, more preferably 0.068 mS / m or less, and 0.017 mS / m. More preferably, it is as follows. The lower the electric conductivity of the carbon dioxide-dissolved water after the deaeration treatment, the lower the (heavy) carbonate ion concentration in the water, and the measured value of the chlorine ion concentration becomes closer to the true chlorine ion concentration.

  In the method of the present invention, the value measured by ion chromatography can be regarded as the chlorine ion concentration as it is, or various degrees of deaeration, that is, various electric conductions, with respect to carbon dioxide-dissolved water in which no chlorine ion is present in advance. The measured value of the chlorine ion concentration is determined for the blank water of the rate, and after degassing the actual carbon dioxide-dissolved water, quantitative analysis is performed. From the measured value of the chlorine ion concentration of the carbon dioxide-dissolved water, the degree of degassing is the same You can also consider the true chloride ion concentration by subtracting the water measurement.

  In the method of the present invention, the degree of degassing of the carbon dioxide-dissolved water can be selected according to the quality of the carbon dioxide-dissolved water required in the washing step. The measured value of the chloride ion concentration obtained by ion chromatography is higher than the true chloride ion concentration due to the influence of (bi) carbonate ions. Therefore, for example, when a chlorine ion concentration of 5.0 ng / L or less is required as the quality of the cleaning water, until the measured value of the chlorine ion concentration of the carbon dioxide-dissolved water after the deaeration treatment is 5.0 ng / L or less. By degassing, it can be confirmed that the true chlorine ion concentration is 5.0 ng / L or less.

  Carbon dioxide-dissolved water is prepared by dissolving carbon dioxide gas in ultrapure water using a dissolution apparatus such as a membrane-type dissolution apparatus, an aeration-type dissolution apparatus, or a suction-type dissolution apparatus in a manufacturing factory for electronic components. The Carbon dioxide-dissolved water discharged from the dissolution apparatus is supplied to the cleaning apparatus via a carbon dioxide-dissolved water supply pipe, and is used as cleaning water or rinse water.

  Carbon dioxide-dissolved water to be evaluated by the method of the present invention can be collected at any position such as the outlet of the dissolution apparatus, the carbon dioxide-dissolved water supply pipe, and the washing machine. In the case where a sampling port is provided in the carbon dioxide dissolved water supply pipe, it is easy to perform sampling by attaching a sampling tube to the sampling port. The sample water may be collected at any time or periodically, or at any time when water quality evaluation of carbon dioxide dissolved water is required, such as when a carbon dioxide dissolving device is newly installed or during periodic inspection. The collected sample water can be degassed and immediately supplied to a quantitative analyzer such as an ion chromatograph for quantification. However, the ion chromatograph is usually installed at a remote location. For this reason, it is preferable to receive the degassed carbon dioxide-dissolved water once in the water collection container.

  The water sampling device for carbon dioxide-dissolved water sample of the present invention is a deaerator for degassing carbon dioxide-dissolved water, an electrical conductivity meter or electrical conductivity for measuring the electrical conductivity of degassed carbon dioxide-dissolved water It has a water sampling container filled with a meter and degassed carbon dioxide-dissolved water.

  FIG. 1 is an explanatory diagram of one embodiment of the method of the present invention and one embodiment of a water sampling device for a carbon dioxide-dissolved water sample. This aspect is an off-line evaluation method. Carbon dioxide-dissolved water is sent to the deaeration device 2 via the pipe 1. For example, the degassing apparatus is configured to reduce the pressure on the gas phase side through a polymer film such as polypropylene, or reduce the pressure while passing an inert gas such as nitrogen gas, and convert carbon dioxide from the liquid phase to the gas phase. A mechanism to move carbon dioxide gas into the gas phase by making carbon dioxide dissolved water into droplets by spraying, increasing the gas-liquid contact area, and bringing it into contact with an inert gas such as nitrogen gas, etc. can do. The electrical conductivity of the water deaerated by the deaerator is measured by the electrical conductivity meter 3. After measuring the electrical conductivity, it is sent to a water sampling box 4 having a mechanism for purifying air by removing chlorine ions in the environment, and injected into a water sampling container 5 in the water sampling box.

  The collected and sealed water sampling container 5 is transported from the location where the carbon dioxide dissolved water is collected to the location where the analyzer is installed. If necessary, in order to move the dissolved gas in the water further to the gas phase, it is moved to the decompression device 6, the water sampling container is opened in the decompression device, and the dissolved gas in the water is degassed under reduced pressure. The Further, deaeration can be further promoted by supplying an inert gas into the water sampling container via the pipe 7. The electrical conductivity of the degassed carbon dioxide-dissolved water can be measured with an electrical conductivity meter 8. When the deaeration is sufficiently performed by the deaeration device 2, the deaeration process by supplying the inert gas via the decompression device 6 and the pipe 7 can be omitted. The carbon dioxide-dissolved water that has been degassed with these is sent to the analyzer 10 by the pump 9 for quantitative analysis. According to this aspect, the carbon dioxide-dissolved water sample having a desired electrical conductivity is measured by deaeration treatment at a place where the carbon dioxide-dissolved water production apparatus is present, Can be collected.

  FIG. 2 is an explanatory diagram of another embodiment of the method of the present invention. This aspect is an on-line evaluation method. Carbon dioxide-dissolved water is sent to the deaeration device 12 via the pipe 11. The water deaerated by the deaerator is measured for electrical conductivity by the electrical conductivity meter 13 and then sent to the water collection container 15 in the decompressor 14. The deaerated water is supplied while overflowing the water collection container 15. If necessary, the decompression device 14 can depressurize the periphery of the water sampling container 15, supply an inert gas to the container 15 via the pipe 16, and perform a deaeration process. The electrical conductivity of the degassed carbon dioxide-dissolved water can be measured with an electrical conductivity meter 17. When the deaeration is sufficiently performed by the deaeration device 12, the deaeration process by supplying the inert gas via the decompression device 14 and the pipe 16 can be omitted. The carbon dioxide-dissolved water degassed with these is sent to the analyzer 19 by the pump 18 for quantitative analysis.

  FIG. 3 is an explanatory view of an embodiment of a water collection box of a degassed carbon dioxide-dissolved water sample used in the present invention. The water sampling box of this aspect includes a water sampling chamber 20, an air supply device 21, a gas-liquid contact device 22, a water circulation path 23, and a gas circulation path 24. The water sampling chamber 20 has a door 25 on the front surface, and the water sampling container 26 can be taken in and out by opening the door. The water sampling chamber has a porous floor plate 27, a water sampling container is placed on the floor plate, and a water storage section 28 is provided under the floor plate. The upper wall of the water sampling chamber has an opening through which the tube 29 connected to the flow path of the carbon dioxide dissolved water is inserted, and the tip of the tube inserted through the opening is inserted to the vicinity of the bottom of the water sampling container.

  A demister 30 for removing water droplets, a gas-liquid contact device 22, a gas filter 31, and a blower fan 32 are connected to the open rear surface of the water sampling chamber. When the blower fan is operated, the gas blows through the gas filter, the gas-liquid contact device, and the demister, enters the water sampling chamber, and circulates from the porous floor plate 27 to the blower chamber 33 via the gas circulation path 24. The water storage section 28 is provided with an overflow pipe 34 to control the water level and secure a gas circulation path.

  To collect the degassed carbon dioxide-dissolved water sample, place the tip of the tube inserted in the water sampling chamber at the bottom of the water sampling container, close the door, and put the sample water into the water sampling container. Supply. The supply of the sample water is continued even if the sample water overflows from the mouth of the water sampling container, thereby washing the water sampling container with the sample water. The overflowing sample water is collected in the water storage section. The water accumulated in the water reservoir is supplied to the sprinkling pipe 36 at the upper part of the gas-liquid contact device by the operation of the circulation pump 35, and flows downward through the gas-liquid contact device to come into contact with the gas. It is removed, and contamination of impurities from the gas phase of the water sampling chamber can be prevented. It is preferable that the inside of the water sampling box be slightly positive pressure to prevent intrusion of outside air into the water sampling box.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
Carbon dioxide-dissolved water was prepared using a functional washing water production apparatus [Kurita Kogyo Co., Ltd., KHOW SYSTEM] equipped with a membrane dissolution apparatus, and chlorine ions in the carbon dioxide-dissolved water were quantified.
The chlorine ion concentration of ultrapure water used for the preparation of carbon dioxide-dissolved water was less than 1 ng / L, and the concentration of carbon dioxide dissolved was 30 mg / L. The test apparatus provided with the deaeration device 37, conductivity meter [Horiba, Ltd., D-54T] 38 and the water sampling device 39 for the carbon dioxide dissolved water sample shown in FIG. Water was supplied. The deaeration device is a device in which a passage of carbon dioxide dissolved water composed of a thin tube made of a gas permeable membrane material is accommodated in the pressure vessel, and the space inside the pressure vessel is depressurized for deaeration treatment. A water sampling apparatus is an apparatus of the structure shown in FIG.
Water was passed for 60 minutes with the internal pressure of the degassing device kept constant, and finally the electrical conductivity of the carbon dioxide dissolved water degassed by the conductivity meter was measured, and the water sampling container was taken out of the water sampling device. The chromatogram of the sample water was obtained using an ion chromatograph [Nippon Daionex Co., Ltd., DX-500], and the measured value of the chlorine ion concentration was calculated from a calibration curve prepared in advance.
When the electric conductivity of the sample water is 0.0675 mS / m, the measured value of the chlorine ion concentration is 10.0 ng / L. When the electric conductivity of the sample water is 0.0242 mS / m, the measured value of the chlorine ion concentration is 5. When the electrical conductivity of the sample water is 0.0166 mS / m, the measured value of the chlorine ion concentration is 2.8 ng / L, and when the electrical conductivity of the sample water is 0.0022 mS / m, the chlorine ion The measured concentration was less than 1.0 ng / L.

Comparative Example 1
The same operation as in Example 1 was performed except that the degree of deaeration treatment was weakened and the electrical conductivity of the sample water was not sufficiently lowered.
When the electrical conductivity of the sample water is 0.144 mS / m, the measured value of the chlorine ion concentration is 18.2 ng / L. When the electrical conductivity of the sample water is 0.113 mS / m, the measured value of the chlorine ion concentration is 15. It was 0 ng / L.
The results of Comparative Example 1 and Example 1 are shown in Table 1.

  As can be seen from Table 1, the measured value of the chlorine ion concentration decreases as the degree of deaeration increases and the sample water has a lower electrical conductivity. When the electric conductivity of the sample water is 0.0675 mS / m or less, it is possible to perform quantification with a chlorine ion concentration of 10 ng / L or less, which is the lower limit of the quantification range. The degree of degassing of the carbon dioxide gas represented by the electrical conductivity of the sample water can be appropriately selected according to the chlorine ion concentration required in the process.

Example 2
The same operation as in Example 1 was performed using test water in which high purity saline (NaCl) was added to the carbon dioxide-dissolved water prepared in Example 1 to obtain a chlorine ion concentration of 10 ng / L.
When the electric conductivity of the sample water is 0.010 mS / m, the measured value of the chlorine ion concentration is 11.8 ng / L. When the electric conductivity of the sample water is 0.0022 mS / m, the measured value of the chlorine ion concentration is 10. It was 3 ng / L.
The results of Example 2 are shown in Table 2.

  As can be seen in Table 2, the carbon dioxide dissolved water with a chlorine ion concentration of 10 ng / L can also be analyzed by ion chromatography after removing the carbon dioxide by degassing to improve the analysis accuracy and the electrical conductivity of the sample water. Is reduced to 0.0024 mS / m, the measured value of the chlorine ion concentration almost coincides with the true chlorine ion concentration.

  According to the method for evaluating carbon dioxide-dissolved water of the present invention, in the manufacturing process of electronic parts and the like, the analysis accuracy of the chlorine ion concentration in the carbon dioxide-dissolved water used as cleaning water is increased, and conventionally it is the lower limit of the quantitative range. In addition, chlorine ions of 10 ng / L or less can be quantified, process management can be facilitated, occurrence of defective products can be prevented, and product quality can be improved. By using the water sampling device for carbon dioxide-dissolved water sample of the present invention, the degassed carbon dioxide-dissolved water sample is sampled and analyzed at a location away from the washing step without causing water quality fluctuations. It can be carried to the device and analyzed accurately.

It is explanatory drawing of 1 aspect of implementation of the method of this invention, and 1 aspect of a water sampling apparatus. It is explanatory drawing of the other aspect of implementation of the method of this invention. It is explanatory drawing of the one aspect | mode of the water sampling box used for this invention. It is explanatory drawing of the apparatus used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piping 2 Deaeration device 3 Electrical conductivity meter 4 Sampling box 5 Sampling container 6 Depressurization device 7 Piping 8 Electrical conductivity meter 9 Pump 10 Analyzer 11 Piping 12 Deaeration device 13 Electrical conductivity meter 14 Decompression device 15 Sampling water Container 16 Piping 17 Electrical conductivity meter 18 Pump 19 Analyzing device 20 Sampling chamber 21 Air feeding device 22 Gas-liquid contact device 23 Water circulation path 24 Gas circulation path 25 Door 26 Sampling container 27 Porous floor plate 28 Water reservoir 29 Tube 30 Demister 31 Gas filter 32 Blower fan 33 Blower chamber 34 Overflow pipe 35 Circulation pump 36 Sprinkling pipe 37 Deaerator 38 Conductivity meter 39 Water sampling apparatus

Claims (2)

Carbon dioxide-dissolved water prepared by dissolving carbon dioxide in ultrapure water, and then deaerated, and then carbon dioxide-dissolved water that has been degassed. In the method of determining by measuring the rate, after degassing the carbon dioxide-dissolved water until the electric conductivity of the carbon dioxide-dissolved water becomes 0.1 mS / m or less , the quantification of chlorine ions An evaluation method for carbon dioxide-dissolved water used in a wet cleaning process of an electronic material, wherein the quantitative accuracy of trace amounts of chlorine ions in carbon dioxide-dissolved water is increased by a method performed by chromatography. A carbon dioxide-dissolved water sample apparatus used in the evaluation method according to claim 1, wherein the carbon dioxide-dissolved water is degassed, and the electric conductivity of the carbon dioxide-dissolved water degassed in the degasser. water sampling device of carbon dioxide gas dissolved water sample and having a water sampling container to be filled electrical conductivity meter or electrical conductivity meter and deaerated carbon dioxide gas dissolved water is measured.

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