JP2000197815A - Device for making ozone-dissolved water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily make extremely high-purity ozone-dissolved water by providing the device with a deaeration device for making deaerated water from ultrapure water, an oxygen dissolving device for making oxygen-dissolved water by dissolving oxygen into the deaerated water and an ultraviolet radiation device for making the ozone-dissolved water by emitting ultraviolet rays to the oxygen-dissolved water. SOLUTION: Ultrapure water is supplied to a deaeration device 2 whose gas chamber is subjected to pressure reduction by an evacuation pump 1 and gas dissolved in the water is deaerated to flow out as deaerated water. Oxygen is fed by an oxygen dissolving device 3 to be dissolved into the deaerated water through an oxygen permeable membrane and the oxygen-dissolved water flows out. This oxygen-dissolved water is further sent to an ultraviolet emission device 4, where the oxygen-dissolved water receives the radiation of ultraviolet rays, and a part or the whole of the dissolved oxygen is converted to ozone, and as ozone-dissolved water it flows out. The ultraviolet radiation device 4 preferably has a radiation source capable of emitting ultraviolet rays of about 185 nm wavelength. Consequently, it is possible to make ozone-dissolved water of a high purity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for producing ozone-dissolved water. More specifically, the present invention can easily produce extremely high-purity ozone-dissolved water used as washing water in a wet washing step for electronic materials and the like, and supply a required concentration of ozone-dissolved water to each use point. The present invention relates to an apparatus for producing ozone-dissolved water.

[0002]

2. Description of the Related Art Removal of fine particles, organic substances, metals, and the like from the surface of electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, and quartz substrates for photomasks is necessary to ensure product quality and yield. Very important. For this purpose, wet cleaning is performed at a high temperature using a concentrated chemical based on hydrogen peroxide, which is a so-called RCA cleaning method, and a mixed solution of ammonia and hydrogen peroxide (APM) or hydrochloric acid and hydrogen peroxide is used. Mixed solution (HPM)
And so on. The use of these cleaning methods reduces the cost of chemical solutions, the cost of ultrapure water for rinsing, the cost of waste liquid treatment, and the cost of air conditioning that exhausts chemical vapors and prepares fresh air. In recent years, the wet cleaning process has been reviewed in order to reduce the burden on the environment such as mass disposal of drugs and emission of exhaust gas. The present inventors have previously developed ozone-dissolved water for cleaning electronic materials in which ozone is dissolved in pure water. Ozone-dissolved water is
Despite having a low dissolved ozone concentration of only a few mg / liter, it exhibits extremely high oxidizing power and removes contamination by impurities such as organic substances and metals attached to the surface of electronic materials. It is used in the process of oxidizing to form a chemical oxide film layer. The ozone-dissolved water has the advantage that the surface of the object to be cleaned is kept clean because there is no residual property, and the ozone-dissolved water becomes high-purity water again by decomposing or removing the ozone and can be reused. Ozone-dissolved water can be produced by dissolving ozone-containing gas produced by an ozone generator in water. The ozone generator uses air or oxygen as a raw material and generates ozone by performing silent discharge between the electrodes, or generates ozone by electrolyzing dilute sulfuric acid using a platinum or lead peroxide electrode. There are devices. As a method for dissolving ozone, an ozone-containing gas is bubbled into water to directly contact gas-liquid, or a gas-permeable membrane module is used to convert ozone from a gas phase into a liquid phase through a hydrophobic gas-permeable membrane. Movement methods have been put to practical use. When the gas permeable membrane module is used, ozone-dissolved water having a relatively stable dissolved ozone concentration and containing no air bubbles can be obtained. In the process of dissolving ozone in water, it is important to transfer gaseous ozone to the aqueous phase at a high dissolution rate, and when using ozone-dissolved water, the dissolved ozone that decreases over time due to self-decomposition The biggest challenge is to keep the concentration substantially constant. In addition, in the production of ozone-dissolved water for wet cleaning of electronic materials and the like, it is also important to prepare high-purity ozone water. Ozone-dissolved water for wet cleaning is generally produced by dissolving a high-purity ozone-containing gas in ultrapure water. There is a possibility that a metal component may be mixed as an impurity into the ozone-containing gas. For this purpose, the electrodes have been coated with ceramics or quartz to suppress mixing of metal components. However, an apparatus that can more easily and easily produce high-purity ozone-dissolved water has been required. Ozone-dissolved water is widely used not only in wet cleaning in the electronics industry but also in the pharmaceutical and food industries for cleaning and disinfection. There has been a strong demand from various fields for an apparatus that can easily produce.

[0003]

The present invention makes it possible to easily produce extremely pure ozone-dissolved water used as washing water in a wet washing step for electronic materials and the like,
An object of the present invention is to provide an apparatus for producing ozone-dissolved water that can supply ozone-dissolved water having a required concentration to each use point.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, after degassing ultrapure water to form degassed water, dissolve oxygen to increase the purity. By preparing oxygen-dissolved water having a high concentration and irradiating the oxygen-dissolved water with ultraviolet rays, it is possible to easily obtain high-purity ozone-dissolved water in which metals are not mixed as impurities. It has been found that the ozone-dissolved water having a required concentration can be stably supplied to the use point by installing the device in the vicinity of the device, and the present invention has been completed based on this finding. That is, the present invention provides (1) a deaerator for deaerated ultrapure water to obtain deaerated water, an oxygen dissolver for dissolving oxygen in the deaerated water to obtain oxygen-dissolved water, and an ultraviolet ray for the oxygen-dissolved water. It is intended to provide an apparatus for producing ozone-dissolved water, which has an ultraviolet irradiation apparatus for obtaining ozone-dissolved water by irradiation. Further, as a preferred embodiment of the present invention,
(2) The apparatus for producing ozone-dissolved water according to item (1), wherein the deaerator is a deaerator module, and (3) the oxygen-dissolver is:
(4) The apparatus for producing ozone-dissolved water according to (1), which is an oxygen-permeable membrane module;
(1) The apparatus for producing ozone-dissolved water according to item (1), wherein the concentration of dissolved oxygen is 20 mg / liter or more.
(4) The apparatus for producing ozone-dissolved water according to item (4), which is not less than 1 liter, (6) the apparatus for producing ozone-dissolved water according to item (1), wherein the ultraviolet irradiation device irradiates ultraviolet light having a wavelength of about 185 nm, and (7) The apparatus for producing ozone-dissolved water according to (1), wherein the inside of the ultraviolet irradiation device is maintained in a pressurized state.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION An apparatus for producing ozone-dissolved water according to the present invention is a deaerator for deaeration of ultrapure water to obtain deaerated water, and oxygen for dissolving oxygen in the deaerated water to obtain oxygen-dissolved water. It has a dissolving device and an ultraviolet irradiation device for irradiating ultraviolet light to oxygen-dissolved water to obtain ozone-dissolved water. FIG. 1 is a process flow chart of one embodiment of the apparatus for producing ozone-dissolved water of the present invention. Ultrapure water is supplied to the deaerator 2 in which the gas chamber is depressurized by the decompression pump 1, and the dissolved gas is deaerated and flows out as deaerated water. The degassed water is then sent to the oxygen dissolving device 3. In the oxygen dissolving device, oxygen is fed into a gas chamber, dissolved in deaerated water through an oxygen permeable membrane, and flows out as oxygen dissolved water. The oxygen-dissolved water is further sent to the ultraviolet irradiation device 4 and, when irradiated with ultraviolet light, part or all of the dissolved oxygen becomes ozone and flows out as ozone-dissolved water. In the apparatus for producing ozone-dissolved water of the present invention, deaerated water is obtained by deaeration of ultrapure water in a deaerator. The deaerator to be used is not particularly limited, and examples thereof include a vacuum deaerator and a decompression membrane deaerator.
Among these, a decompression membrane deaerator using a degassing membrane module can be used particularly preferably because a very small amount of dissolved gas can be degassed without impairing the purity of ultrapure water. The ultrapure water to be supplied to the apparatus of the present invention may be 2
An electric resistivity at 5 ° C. of 18.0 MΩ · cm or more;
It is preferable that the concentration of organic carbon be 10 μg / liter or less, and the concentrations of copper and iron be 20 ng / liter or less, respectively. As the ultrapure water to be supplied, dissolved oxygen can be used by removing dissolved oxygen by degassing with nitrogen and saturated with almost only nitrogen, or ultrapure water in equilibrium with the atmosphere can be used. . Pressure 10 ⁵ P
a, At a temperature of 20 ° C., nitrogen-dissolved water saturated only with nitrogen has dissolved 19.2 mg / liter of nitrogen. At a pressure of 10 ⁵ Pa and a temperature of 20 ° C., ultrapure water in equilibrium with the atmosphere contains 14.9 mg / liter of nitrogen and 9.1 oxygen.
mg / litre dissolved and saturated.

[0006] In the apparatus of the present invention, ultrapure water is degassed to form degassed water having a reduced degree of saturation, thereby creating a space in the gas dissolving capacity and facilitating the dissolution of oxygen in the oxygen dissolving apparatus. I do. The degree of saturation is a value obtained by dividing the amount of gas dissolved in ultrapure water at a pressure of 10 ⁵ Pa by the solubility of the gas. The water saturation is 0.5 times. If ultrapure water with a saturation level of 1 times saturated with nitrogen is sent to the oxygen dissolving apparatus as it is, the removal of nitrogen and the dissolution of oxygen will be performed simultaneously through the gas permeable membrane. However, it is necessary to discard the mixed gas of oxygen and nitrogen generated in the gas chamber.However, if the space for dissolving the gas in ultrapure water is made and sent to the oxygen dissolving device, the oxygen is quickly turned into deaerated water. Since the gas is dissolved and the gas chamber is maintained in a state filled with oxygen, the gas can be dissolved almost quantitatively without wasteful release of oxygen. At a temperature of 20 ° C., the solubility of oxygen in water is 44.0 mg /
Liters. When 14.4 mg / liter of nitrogen is degassed from nitrogen-dissolved water saturated only with nitrogen, the amount of dissolved nitrogen becomes 4.8 mg / liter, that is, the saturation becomes 0.25 times, and the dissolution capacity becomes 0.2% of the saturation. Since a space equivalent to 75 times is created, 33.0 mg / liter of oxygen equivalent to 0.75 times the degree of saturation can be easily dissolved in the oxygen dissolving apparatus. In the apparatus of the present invention, the gas permeable membrane used for the deaerator is not particularly limited. For example, a polypropylene membrane, a polydimethylsiloxane membrane, a polycarbonate-polydimethylsiloxane block copolymer membrane, and a polyvinylphenol-polydimethylsiloxane-polysulfone block copolymer may be used. Polymer membrane, poly (4-methylpentene-1) membrane, poly (2,6-dimethylphenylene oxide)
And a polytetrafluoroethylene film.

In the apparatus for producing ozone-dissolved water according to the present invention, oxygen is dissolved in deaerated water in an oxygen dissolution apparatus to obtain oxygen-dissolved water. There is no particular limitation on the oxygen dissolving device used, for example, a bubbling device, a line mixing device,
A gas permeable membrane device can be used. Among these, the gas permeable membrane device using the gas permeable membrane module,
It is particularly preferably used because the amount of dissolved oxygen per unit time and per unit space is large, and the efficiency of dissolving oxygen can be increased without impairing the purity of ultrapure water. In the apparatus of the present invention, the concentration of the oxygen-dissolved water is not particularly limited, and can be appropriately selected according to the required ozone concentration of the ozone-dissolved water. Using the same ultraviolet irradiation device,
Even if the same wavelength and the same dose of ultraviolet rays are irradiated, the higher the oxygen concentration of the oxygen-dissolved water, the higher the ozone concentration of the obtained ozone-dissolved water. In the apparatus of the present invention, the inside of the ultraviolet irradiation device can be pressurized, more preferably 2 × 10 ⁵ Pa or more. By changing the inside of the ultraviolet irradiation device to a pressurized state, the oxygen changes to ozone, the saturation of the ozone-dissolved water exceeds 1 time, and even when the supersaturated state at normal pressure is reached, the gas is prevented from being volatilized by foaming. be able to. In the apparatus of the present invention, the gas permeable membrane used in the oxygen dissolving apparatus is not particularly limited. For example, a polypropylene membrane, a polydimethylsiloxane membrane, a polycarbonate-polydimethylsiloxane block copolymer membrane, and a polyvinylphenol-polydimethylsiloxane-polysulfone block copolymer may be used. Polymer membrane, poly (4-methylpentene-1) membrane, poly
(2,6-dimethylphenylene oxide) film, polytetrafluoroethylene film and the like.

[0008] In the apparatus for producing ozone-dissolved water of the present invention, it is preferable that the ultraviolet irradiation device has a radiation source capable of irradiating ultraviolet light having a wavelength of about 185 nm. Ultraviolet light having a wavelength of about 185 nm is absorbed by oxygen,
Converts oxygen to ozone. Examples of the ultraviolet ray source having a wavelength of about 185 nm include a low-pressure mercury lamp, a hydrogen discharge tube,
Higher harmonics of a dye laser can be used.
In addition, as a material of a window, a prism, and a lens that transmit ultraviolet light having a wavelength of 185 nm, fused quartz, sapphire, or the like can be used. Since ultraviolet rays having a wavelength of about 254 nm decompose ozone, it is preferable to use a radiation source containing as little as possible ultraviolet rays having a wavelength of about 254 nm. In the apparatus for producing ozone-dissolved water of the present invention, the ultraviolet irradiation device can be arranged close to the oxygen dissolving device, can be arranged near the use point, or a plurality of ultraviolet irradiation devices can be arranged at a distance. They can also be placed apart. Since oxygen in oxygen-dissolved water has no self-decomposition property,
The oxygen concentration is kept constant. Therefore, even if the ultraviolet ray is irradiated near the oxygen dissolving device or the ultraviolet ray is irradiated near the use point, ozone-dissolved water can be obtained by similarly changing oxygen to ozone. Also, ozone-dissolved water prepared by an ultraviolet irradiator close to the oxygen dissolver is sent over a long distance through a pipe, and when the ozone concentration decreases due to self-decomposition, ultraviolet light is emitted using a small ultraviolet irradiator near the point of use. Irradiate,
The ozone concentration can be restored by changing the oxygen to ozone again. Furthermore, even when the required ozone concentration differs depending on the use point, the required concentration of ozone-dissolved water is supplied to each use point by irradiating ultraviolet rays using an ultraviolet irradiation device provided near the use point. be able to. In the apparatus for producing ozone-dissolved water of the present invention, the ozone-dissolved water is prepared by irradiating ultraviolet rays to the oxygen-dissolved water without using a so-called ozone generator of a silent discharge method or an electrolysis method. An extremely high-purity ozone-dissolved water can be produced without any gas or ozone-containing gas coming into contact with it, and hence no contamination by metals, which are impurities derived from the electrodes. In addition, when ozone is self-decomposed in ozone-dissolved water and becomes oxygen, and the ozone concentration drops, a small ultraviolet irradiation device is installed to irradiate ultraviolet light, and the oxygen is easily restored to ozone, thereby easily recovering the ozone concentration. can do.

[0009]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Ozone-dissolved water was prepared using an apparatus connected to a degassing apparatus, an oxygen dissolving apparatus, and an ultraviolet irradiation apparatus shown in FIG. The gas chamber of the deaerator equipped with a polypropylene membrane is maintained at 20 Torr using a water ring vacuum pump, and ultrapure water is supplied to the water chamber to perform deaeration, and a degassing with a dissolved nitrogen concentration of 5.5 mg / liter. Steam water was prepared. The degassed water is sent through a pipe to an oxygen dissolving apparatus equipped with a polypropylene membrane to dissolve high-purity oxygen to prepare oxygen-dissolved water having a dissolved oxygen concentration of 20.0 mg / liter and a dissolved nitrogen concentration of 5.5 mg / liter. did. This oxygen-dissolved water is supplied through a pipe to a fused quartz lamp power 4
Sent to an ultraviolet irradiation device equipped with a 00W low-pressure mercury lamp,
Irradiation with ultraviolet light having a line spectrum of 85 nm, dissolved ozone concentration 3.5 mg / liter, dissolved oxygen concentration 16.5 mg
Per liter of ozone-dissolved water having a dissolved nitrogen concentration of 5.5 mg / liter was prepared. About the obtained ozone dissolved water, using an inductively coupled plasma mass spectrometer, magnesium,
Aluminum, titanium, chromium, iron, nickel, copper, zinc, silver, tantalum, tungsten and lead were analyzed. The concentrations of these metals in the ozone-dissolved water were all 1 ng / liter or less, and no difference was observed between the ozone-dissolved water and the ultrapure water used as the raw material. Comparative Example 1 Ozone-dissolved water was prepared using an apparatus equipped with a deaerator, an ozone generator, and an ozone-dissolving film module. The gas chamber of the deaerator equipped with a polypropylene membrane is maintained at 20 Torr using a water ring vacuum pump, and ultrapure water is supplied to the water chamber to perform deaeration, and a degassing with a dissolved nitrogen concentration of 5.5 mg / liter. Steam water was prepared. This degassed water is passed through a pipe and the diameter is 100m.
m, a mixed ozone and oxygen gas generated by a commercially available silent discharge type ozone generator is sent to a commercially available ozone dissolving membrane module with a length of 1,000 mm and a dissolved ozone concentration of 3.5 m
g / L, dissolved oxygen concentration 10.0 mg / L, and dissolved nitrogen concentration 5.5 mg / L were prepared. About the obtained ozone dissolved water, using an inductively coupled plasma mass spectrometer, magnesium, aluminum,
Titanium, chromium, iron, nickel, copper, zinc, silver, tantalum, tungsten and lead were analyzed. In the ozone-dissolved water, 3 ng / l of titanium, 2 ng / l of iron and 3 ng / l of lead were detected, and the concentrations of other metals were all 1 ng / l or less. Table 1 shows the analysis results of the ultrapure water used as the raw material, the ozone-dissolved water of Example 1, and the ozone-dissolved water of Comparative Example 1.

[0010]

[Table 1]

As shown in Table 1, Example 1 was manufactured by irradiating oxygen-dissolved water with ultraviolet rays using the apparatus of the present invention.
No difference in water quality between the ultrapure water used as the raw material and the ozone-dissolved water was observed, but the ozone-containing gas generated by the ozone generator was dissolved in degassed water using an ozone-dissolved membrane module. It can be seen that the ozone-dissolved water of Comparative Example 1 has a higher concentration of titanium, iron and lead than the ultrapure water used as the raw material, and is contaminated by the metal. Example 2 Using the same apparatus as in Example 1, ozone-dissolved water was prepared. In the degassing device, degassed water having a dissolved nitrogen concentration of 4.0 mg / l was prepared, and the degassed water was sent to an oxygen dissolving device to dissolve high-purity oxygen, and a dissolved oxygen concentration of 2.0 mg / l was dissolved. Oxygen-dissolved water having a nitrogen concentration of 4.0 mg / liter was prepared. The oxygen-dissolved water was sent to an ultraviolet irradiation device and irradiated with ultraviolet light to prepare ozone-dissolved water. The dissolved ozone concentration of the obtained ozone-dissolved water was 1.2 mg / liter. The dissolved oxygen concentration of the oxygen-dissolved water was 10.0 mg /
The preparation of ozone-dissolved water was repeated in the same manner with the addition of 20.0 mg / liter and 30.0 mg / liter. The dissolved ozone concentrations were 2.5 mg / liter and 3.3, respectively.
mg / l and 4.0 mg / l. Table 2 shows the results of Example 2.

[0012]

[Table 2]

From the results shown in Table 2, it can be seen that the dissolved ozone concentration of the obtained ozone-dissolved water varies depending on the dissolved oxygen concentration of the oxygen-dissolved water, and the dissolved ozone concentration increases as the dissolved oxygen concentration increases. Example 3 The prepared ozone-dissolved water was fed using a Teflon-made pipe, and then irradiated with ultraviolet rays to recover the reduced dissolved ozone concentration. The gas chamber of the deaerator equipped with a polypropylene membrane was maintained at 20 Torr using a water ring vacuum pump, and degassing was performed by supplying ultrapure water to the water chamber, and degassing was performed with a dissolved nitrogen concentration of 4.0 mg / liter. Steam water was prepared. The degassed water is sent through a pipe to an oxygen dissolving apparatus equipped with a polypropylene membrane to dissolve high-purity oxygen, and to dissolve the dissolved oxygen at a concentration of 30.
Oxygen-dissolved water having a concentration of 0 mg / liter and a dissolved nitrogen concentration of 4.0 mg / liter was prepared. The oxygen-dissolved water is sent through a pipe to an ultraviolet irradiation device I equipped with a low-pressure mercury lamp with a lamp power of 150 W made of fused quartz and irradiated with ultraviolet light having a line spectrum of 185 nm to dissolve dissolved ozone at a concentration of 4.0 mg / liter. Ozone-dissolved water having an oxygen concentration of 26.0 mg / l and a dissolved nitrogen concentration of 4.0 mg / l was prepared. When this ozone-dissolved water was sent 100 m through a Teflon pipe, the dissolved ozone concentration at the outlet of the pipe was reduced to 2.0 mg / liter. Then, an ultraviolet irradiation device II equipped with a low-pressure mercury lamp with a lamp power of 150 W made of fused silica was attached to the end of the pipe, and the ozone-dissolved water was irradiated with ultraviolet light having a line spectrum of 185 nm. The dissolved ozone concentration of the dissolved water was 4.1 mg / liter. Table 3 shows the results of Example 3.

[0014]

[Table 3]

As can be seen from Table 3, even with ozone-dissolved water having a reduced dissolved ozone concentration, which is sent through a long-distance pipe, the dissolved ozone concentration can be increased by irradiating ultraviolet rays with an ultraviolet irradiation device. Recovers. Furthermore, from this result, it is possible to prepare an ozone-dissolved water having a required dissolved ozone concentration by providing an ultraviolet irradiation device near the use point and irradiating the ozone-dissolved water with a necessary dose of ultraviolet light. I understand.

[0016]

By using the apparatus for producing ozone-dissolved water of the present invention, extremely high-purity ozone-dissolved water can be easily produced. The reduced dissolved ozone concentration can be recovered by providing the ultraviolet irradiation device.

[Brief description of the drawings]

FIG. 1 is a process flow diagram of one embodiment of an apparatus for producing ozone-dissolved water of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Decompression pump 2 Deaerator 3 Oxygen dissolving device 4 Ultraviolet irradiation device

Claims (1)

[Claims] 1. A degassing device for degassing ultrapure water to obtain degassed water,
An apparatus for producing ozone-dissolved water, comprising: an oxygen dissolving apparatus for dissolving oxygen in degassed water to obtain oxygen-dissolved water; and an ultraviolet irradiation apparatus for irradiating ultraviolet light to the oxygen-dissolved water to obtain ozone-dissolved water.