JP5638193B2 - Cleaning method and cleaning apparatus - Google Patents

Description

  The present invention relates to a cleaning method and a cleaning apparatus, and more particularly to a cleaning method and a cleaning apparatus for cleaning an electronic component or a component used in a manufacturing apparatus or a cleaning apparatus.

  Electronic parts such as semiconductor substrates are precise, and if there are contaminants on the surface, the performance and function of the electronic component will be defective. Therefore, the surface is required to be clean. Examples of contaminants on the surface of an electronic component include, for example, liquid contact surfaces of various components (for example, a filter for filtration, a filter housing for filtration, a pipe, a wafer carrier, a cleaning tank, and a pump) in the electronic device manufacturing apparatus and cleaning apparatus. Organic matter and inorganic matter that have adhered to the surface. Therefore, the surface is required to be clean not only for the electronic component itself but also for various components used in the manufacturing apparatus and the cleaning apparatus.

As a method for removing contaminants present on the surface of such a component, there is known a cleaning method in which ultraviolet rays are irradiated while an object to be cleaned (component) is immersed in a cleaning liquid containing ozone (Patent Documents 1 and 2). .
JP-A-4-179225 Japanese Patent Laid-Open No. 5-291221

  In the above method, there is a problem that the contaminant removal effect can be obtained to some extent on the ultraviolet irradiation surface of the component, but the contaminant cannot be sufficiently removed on the surface not exposed to ultraviolet rays. Such a problem is remarkable when the object to be cleaned (part) has a complicated shape. Also, in the above method, when the object to be cleaned is a pipe, it is difficult to irradiate the inner surface with ultraviolet rays, so it is difficult to remove contaminants on the inner surface.

  An object of the present invention is to provide a cleaning method and a cleaning apparatus capable of sufficiently removing contaminants on the surface of the object to be cleaned even when the object to be cleaned has a complicated shape.

  The present invention relates to a cleaning method characterized by contacting ozone water in which ozone is dissolved in pure water with ultraviolet rays to obtain a cleaning liquid and then bringing the cleaning liquid into contact with an object to be cleaned.

  The present invention also provides an ultraviolet irradiation treatment tank for obtaining cleaning liquid by irradiating ozone water in which ozone is dissolved in pure water, and means for bringing the cleaning liquid in the ultraviolet irradiation treatment tank into contact with an object to be cleaned. The present invention relates to a cleaning apparatus.

  According to the present invention, once the cleaning liquid is obtained, the contaminants on the surface can be sufficiently removed simply by bringing the cleaning liquid into contact with the object to be cleaned. Therefore, even when the object to be cleaned has a complicated shape or a pipe, such a contaminant removal effect of the present invention can be obtained effectively. Further, by dissolving a specific water-soluble organic substance in the cleaning liquid, the contaminant removal effect is further improved and maintained for a relatively long time.

  The cleaning method of the present invention is a method for removing contaminants on the surface of an object to be cleaned, and is effective in the form of particles regardless of whether the contaminants are organic, inorganic or fungi. It can be removed.

  The object to be cleaned to which the cleaning method of the present invention is applicable is not particularly limited, but is preferably a precision part whose surface needs to be strictly cleaned. This is because contaminants can be effectively removed without affecting the object to be cleaned itself. Such precision components include electronic components such as silicon wafers, printed boards, glass substrates, liquid crystal substrates, magnetic disk substrates, compound semiconductor substrates, and the like; and various parts in such electronic component manufacturing apparatuses and cleaning apparatuses, such as , Filter for filtration, filter housing for filtration, piping, wafer carrier, washing tank, pump and the like.

  The cleaning method of the present invention will be described in detail with reference to FIG. 1 showing a schematic diagram of an example of a cleaning apparatus employing the cleaning method of the present invention.

  In the present invention, first, ozone water is prepared by dissolving ozone in pure water. The ozone water preparation method is not particularly limited as long as ozone can be dissolved in pure water, for example, by filling the ozone dissolving apparatus 1 with pure water 2 and supplying ozone generated by the ozonizer 3 therein, Ozone water can be obtained. The ozonizer 3 is connected to the oxygen cylinder 4 and generates ozone from the oxygen supplied from the oxygen cylinder 4. As the ozonizer 3, a known ozone generator can be used. For example, a general-purpose water-cooled ozone generator, a silent discharge type ozone generator, and the like are available, and are commercially available from Sumitomo Precision Industries, Regal Joint, Ecodesign, etc. Has been.

  Pure water is water from which impurities have been removed, and usually water having an electrical resistivity of 15 MΩ · cm or more is used. From the viewpoint of cleaning an electronic component or a component used in its manufacturing apparatus or cleaning device (hereinafter referred to as an electronic component or the like), ultrapure water having an electrical resistivity of 17 MΩ · cm or more is preferably used. The electrical resistivity can be measured using a commercially available specific resistivity meter.

  The ozone concentration in the ozone water is not particularly limited as long as the object of the present invention is achieved, and is usually 1 to 100 ppm, particularly 3 to 50 ppm. If the ozone concentration decreases, the cleaning effect decreases, and if the ozone concentration increases, the process of dissolving ozone in pure water becomes extremely difficult. As shown in FIG. 1, a concentration meter 21 (for example, an absorptiometer “Water Riser” (Kurashiki Spinning) for measuring the concentration of ozone is provided in the middle of a pipe 12 connecting the pump 11 and the ultraviolet irradiation treatment tank 6. Etc.), an in-line dissolved ozone monitor (Ebara Jitsugyo Co., Ltd.) etc. is provided, and the ozone concentration can be calculated and measured. In the present specification, the unit “ppm” indicating concentration and the like indicates a ratio to the total amount on a weight basis.

  It is preferable to further dissolve water-soluble organic substances in ozone water. By dissolving a water-soluble organic substance in ozone water, generation of hydroxy radicals by ultraviolet irradiation described later is promoted. As a result, the ability to remove contaminants by the cleaning liquid is not only further improved, but also maintained for a relatively long time. The water-soluble organic substance 5 may be added before dissolving ozone in pure water, simultaneously with ozone dissolution, or after ozone dissolution, but before dissolving ozone in pure water, It is preferred that they be simultaneous.

  The water-soluble organic substance is an ozone reaction rate constant of 10 L / mol / sec or less, particularly 1.0 L / mol / sec or less, preferably 0.001 to 1.0 L / mol / from the viewpoint of generation of hydroxy radicals by ultraviolet irradiation described later. The one of sec is used. The ozone reaction rate constant is a reaction rate constant at the time of reaction with ozone. The smaller the ozone reaction rate constant, the more difficult it is to react with ozone. By using a water-soluble organic substance having a relatively small ozone reaction rate constant as described above, the water-soluble organic substance itself can also contribute to the generation of radicals by ultraviolet irradiation without inhibiting the generation of hydroxy radicals by ozone. The ozone reaction rate constants of various compounds can be known from known literatures, for example, Table 2 in “Ozone treatment and hydroxyl radical” (written by Shigeki Nakayama) published by the 4th “Ozone Radical Sterilization and Deodorization Study Group”. .2 “Reaction rate constants of ozone and OH radicals and compounds in water”.

  Examples of such water-soluble organic substances include alcohols such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, and t-butanol, acetone, acetic acid, formic acid, citric acid, and the like. .

  Among the above water-soluble organic substances, those having a relatively low boiling point are preferably used from the viewpoint of washing of electronic parts and the like, for example, n-propanol, iso-propanol, n-butanol, iso-butanol, t-butanol and the like. Is mentioned. The most preferred water-soluble organic substance is iso-propanol (isopropanol).

  The concentration of the water-soluble organic substance is usually 100 ppm or less, preferably 0.001 to 10 ppm, more preferably 0.01 to 5 ppm. Concentration of the water-soluble organic matter is provided in the middle of the pipe 12 connecting the pump 11 and the ultraviolet irradiation treatment tank 6 (not shown) (for example, UV organic matter meter UVAS-sc (manufactured by Central Science Co., Ltd.)). Can be measured.

  After obtaining the ozone water, the ozone water is irradiated with ultraviolet rays to prepare a cleaning liquid. The cleaning liquid preparation method is not particularly limited as long as it can irradiate ozone water with ultraviolet rays. For example, ozone water prepared in the ozone dissolving apparatus 1 is applied to the ultraviolet irradiation treatment tank 6 through a pipe line 12 by a pump 11 or the like. The cleaning liquid can be obtained by supplying and causing the ultraviolet lamp to emit light in the apparatus. When supplying the ozone water to the ultraviolet irradiation treatment tank 6, as shown in FIG. 1, the pipe may be branched from the pump 11, and the ozone water may be returned to the ozone dissolving apparatus 1 through the pipe 13 and circulated. .

  Hydroxyl radicals are generated based on the following routes (I) and (II) by ultraviolet irradiation of ozone water.

Route (I);
O ₃ + H ₂ O → HO ₃ ⁺ + OH ⁻
HO ₃ ⁺ + OH ⁻ → 2HO ₂ ·
O ₃ + HO ₂ → OH / + 2O ₂

Pathway (II);
O ₃ + H ₂ O + hν → H ₂ O ₂ + O ₂
H ₂ O ₂ + hν → 2OH ·

  Hydroxyl radicals generated by such a route exert a contaminant removal effect based on the following actions and mechanisms. Since the hydroxy radical has a strong oxidizing action and bactericidal action, it acts to neutralize the electric charge of the pollutant so that the neutralized pollutant is released from the surface of the object to be cleaned and hardly reattached. Moreover, such a cleaning liquid can exhibit the above-described contaminant removal effect without affecting the object to be cleaned. Further, this effect is maintained at a practical time level even when the cleaning liquid in which hydroxy radicals are generated is taken out of the system and used. For this reason, even if such a cleaning liquid is brought into contact with an object to be cleaned by a shower method as well as an immersion method, the effect can be effectively exhibited.

  Dissolving water-soluble organic substances in ozone water not only improves the ability of the cleaning liquid to remove contaminants, but details of the phenomenon that is maintained over a relatively long period of time are not clear. It is thought that it is based on. Since water-soluble organic substances react with hydroxyl radicals in a chain reaction by ultraviolet irradiation and show a synergistic effect with hydroxy radicals, it is considered that a remarkable improvement and long-term continuation of pollutants can be achieved.

  A known ultraviolet generator can be used as the ultraviolet lamp, and examples thereof include a low-pressure mercury lamp SUV-40 (manufactured by Sen Special Light Source Co., Ltd.).

  The ultraviolet light may be irradiated to such an extent that the object of the present invention is achieved. For example, the ultraviolet light may be irradiated at such an irradiation amount that a hydroxyl radical concentration described below is achieved in the cleaning liquid. Specifically, the ultraviolet lamp is usually irradiated at an irradiation dose corresponding to 1 to 600 seconds at 0.1 to 25 W / L.

  Presence of hydroxy radicals contained in the cleaning liquid is to be used for electron spin resonance (ESR: Electron Spin Resonance) (also called Electron Paramagnetic Resonance) using a free radical monitor JES-FR30 (manufactured by JEOL Ltd.). Can be confirmed. For example, the cleaning liquid obtained by the ultraviolet irradiation is applied to the monitor, and it can be confirmed from the obtained ESR chart whether or not there is a peak indicating the presence of hydroxy radicals.

The concentration of the hydroxy radical in the cleaning liquid is not particularly limited as long as the object of the present invention is achieved. For example, the concentration is 1.0 × 10 ^{−6 to} 8.0 × 10 ⁻⁵ mol / L, particularly 2.0. × 10 ^{−6 to} 4.0 × 10 ⁻⁵ mol / L is preferable.

  The concentration of the hydroxy radical can be measured, for example, by DMSO (dimethyl sulfoxide) method. Specifically, the washing liquid immediately after preparation is collected, and DMSO is added thereto to react DMSO with hydroxy radicals. The reaction follows the following reaction equation: the amount of methanesulfonic acid produced by the reaction is equal to the amount of DMSO reacted and the amount of hydroxy radicals. Therefore, the hydroxy radical concentration can be calculated from the measured value obtained by measuring the amount of methanesulfonic acid produced by the reaction with an ion chromatograph and the amount of the cleaning solution used for the measurement.

(CH ₃ ) ₂ SO + · OH → CH ₃ S (O) OH + · CH ₃
CH ₃ S (O) OH + · OH + O ₂ → CH ₃ S (O) ₂ OH + · OOH
(CH ₃ ) ₂ SO + · OOH → CH ₃ S (O) ₂ OH + · CH ₃

  The cleaning liquid used in the present invention preferably exhibits a reduction in oxidation-reduction potential from 800 mV to 200 mV at a reduction rate of 100 mV / second or less. This is because when the cleaning liquid having a reduction rate of the oxidation-reduction potential exceeding 100 mV / second is used, the content of hydroxy radicals is considered to be low, and the cleaning effect tends to be low. The reduction rate of the oxidation-reduction potential is more preferably 10 mV / second or less because a more excellent cleaning effect is exhibited.

  The decreasing rate of the oxidation-reduction potential of the cleaning liquid can be measured by the following method. For example, after the cleaning liquid immediately after preparation in FIG. 1 is supplied to a 100 ml beaker into which an ORP electrode of a portable ORP meter RM-20P (manufactured by Toa DKK Corporation) is inserted and overflowed, the beaker is removed from the system. Remove the cleaning liquid supply to the beaker. Then, the rate of reduction of the oxidation-reduction potential per second is calculated from the ORP values measured by the portable ORP meter RM-20P immediately after removing the beaker and after 10 seconds.

  Further, for example, as shown in FIG. 1, an oxidation-reduction potentiometer 23 (for example, an industrial ORP meter) is provided in the middle of a pipe line 15 that connects the ultraviolet irradiation treatment tank 6 and a means 7 for bringing the cleaning liquid into contact with the object to be cleaned. HDM-138A (manufactured by Toa DKK Co., Ltd.) may be provided, and thereby the oxidation-reduction potential may be measured. The basic measurement method is the same as that when the portable ORP meter RM-20P is used.

  After obtaining the cleaning liquid, the cleaning liquid is brought into contact with the object to be cleaned. Specifically, the cleaning liquid obtained in the ultraviolet irradiation treatment tank 6 is supplied to the means 7 for bringing the cleaning liquid into contact with the object to be cleaned through the conduit 15.

  The means 7 for bringing the cleaning liquid into contact with the object to be cleaned is not particularly limited as long as the contact between the cleaning liquid and the object to be cleaned can be ensured. For example, a shower head for applying the cleaning liquid to the object to be cleaned by the shower method. It may be an immersion tank for immersing the object to be cleaned in the cleaning liquid. The contact means 7 employs any method, and the cleaning liquid is preferably flowing from the viewpoint of effective removal of contaminants. For example, when an immersion tank is used, the cleaning liquid is used while being stirred in the immersion tank. When the object to be cleaned is a filter, the contact means 7 may be a filter attaching device for attaching the filter in a pipe line connected to the pipe line 15 and permeating the cleaning liquid flow.

  The contact time between the cleaning liquid and the object to be cleaned cannot be generally defined, and may be set according to the degree of contamination of the object to be cleaned, the method of the contact means 7, the required degree of cleaning, and the like.

  According to the cleaning method of the present invention described above, the concentration of hydroxy radicals in the cleaning liquid becomes relatively high and the concentration can be maintained, so that the cleaning effect is improved and such an excellent cleaning effect is maintained for a relatively long time. Can have. For example, as shown in FIG. 6 obtained in Experimental Example 5 which will be described later, the cleaning liquid X1 obtained by irradiating ozone water containing a water-soluble organic substance with ultraviolet rays is more hydroxyl radicals in the cleaning liquid than the cleaning liquid X3 not irradiated with ultraviolet rays. Since the concentration can be maintained high, the cleaning effect is improved, and such an excellent cleaning effect can be obtained over a relatively long period. FIG. 6 is a graph showing the change with time of the hydroxy radical concentration in various cleaning solutions. FIG. 7 shows the change with time of the ozone concentration at this time.

  In particular, in the present invention, immediately after the cleaning liquid is obtained by irradiating ozone water with ultraviolet rays, the cleaning liquid is brought into contact with the object to be cleaned, thereby further increasing the hydroxy radical concentration in the cleaning liquid at the time of contact with the object to be cleaned. Since it can be made higher, the cleaning effect is further improved. For example, as shown in the cleaning liquid X2 in FIG. 6, when ozone water containing a water-soluble organic substance is irradiated with ultraviolet rays, the concentration of hydroxy radicals in the cleaning liquid is significantly increased. When brought into contact with an object to be cleaned, the cleaning effect is remarkably excellent.

  The shorter the time from when the cleaning liquid is obtained by irradiating ultraviolet rays until the cleaning liquid is brought into contact with the object to be cleaned, the higher the hydroxy radical concentration in the cleaning liquid, the better. In the present invention, specifically, the time is preferably 360 seconds or less, more preferably 180 seconds or less, and still more preferably 60 seconds or less.

  The present invention will be described in more detail by the following experimental examples, but it is obvious that the present invention should not be construed as being limited to the following experimental examples.

The filter was cleaned by the cleaning apparatus shown in FIG. That is, cleaning evaluation was performed using various cleaning solutions manufactured under predetermined operating conditions in each experimental example. Specifically, as means 7 for bringing the cleaning liquid into contact with the object to be cleaned, a filter as the object to be cleaned is attached in a pipe line connected to the pipe line 15 so that the cleaning liquid permeates the filter. The filter mounting tool was used. With respect to the cleaning liquid immediately after passing through the object to be cleaned (filter) in the contact means 7, particles having a particle diameter of 0.2 μm were cumulatively counted by a particle counter (KL22; manufactured by Lion Corporation). The particles are released and removed from the filter by permeation of the cleaning liquid.
The filter to be cleaned is a polytetrafluoroethylene filter (manufactured by Advantech) immersed in ultrapure water (electric resistivity 18 MΩ · cm) at 30 ° C. for one week.

As pure water 2, ultrapure water (electric resistivity 18 MΩ · cm) produced by an ultrapure water production apparatus was supplied to the ozone dissolution apparatus at 1 L / min.
When the operation of the ozonizer 3 was performed, oxygen gas was supplied from the oxygen cylinder 4 to a silent discharge type ozone generator (manufactured by Regal Joint) as the ozonizer 3 at 1 L / min. Ozone gas was generated by the ozonizer 3 and supplied to the ozone dissolution apparatus 1 (aeration tube system) at 1 L / min. In the ozone dissolving apparatus 1, the ultrapure water supplied from the ultrapure water production apparatus was always stored in 2 L, and ozone gas was blown into the ultrapure water through a diffuser tube to generate ozone water.
The ozone water generated by the ozone dissolving apparatus 1 was supplied to the ultraviolet irradiation treatment tank 6 at 0.8 L / min while partially circulating with a pump 11, and overflowed at 0.2 L / min.
When supplying the water-soluble organic substance 5, the water-soluble organic substance 5 was supplied to the ozone dissolution apparatus so as to have a predetermined concentration in the form of a 1000 ppm solution previously mixed with ultrapure water using iso-propanol.
In the case of irradiation with ultraviolet rays, a low-pressure mercury lamp SUV-40 (manufactured by Sen Special Light Source) was irradiated at a dose equivalent to 5 W at 0.3 W / L.

The ozone concentration was calculated and measured with a densitometer 21 (an absorptiometer “Water Riser” (manufactured by Kurashiki Boseki)).
The reduction rate of the oxidation-reduction potential was measured with an oxidation-reduction potentiometer 23 (industrial ORP meter HDM-138A; manufactured by Toa DKK Corporation).
The hydroxy radical concentration was measured by the DMSO method using a separate cleaning solution obtained under the same conditions as in the experimental examples described later.
The cleaning apparatus in FIG. 1 is a continuous operation type, and ultrapure water was continuously supplied and a pump 11 was used so that a cleaning liquid was produced at a flow rate of 0.8 L / min. The time from when the cleaning liquid left the ultraviolet irradiation treatment tank 6 to the filter as the object to be cleaned was 2 seconds.

(Experimental example 1)
The operation of supplying the ultrapure water 2 and the water-soluble organic substance 5 was performed until 20 minutes passed from the start of the experiment. However, the operation of the ozonizer 3 and the light emission of the low-pressure mercury lamp were stopped, and the cleaning liquid A1 was produced and the cleaning evaluation was performed. went. The ozone concentration was 0 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 0 mV / second, and the hydroxy radical concentration was 0 mol / L.
From the 20 minutes after the start of the experiment until 60 minutes passed, the supply operation of the ultrapure water 2 and the water-soluble organic substance 5, the operation of the ozonizer 3 and the light emission of the low-pressure mercury lamp were performed to produce the cleaning liquid B1, and the cleaning evaluation was performed. . The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 1 mV / second or less, and the hydroxy radical concentration was 3.0 × 10 ⁻⁶ mol / L.
The operation of supplying the ultrapure water 2 and the water-soluble organic substance 5 and the operation of the ozonizer 3 were performed until 80 minutes after the start of the experiment, but the emission of the low-pressure mercury lamp was stopped to produce the cleaning liquid C1. Cleaning evaluation was performed. The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the oxidation-reduction potential was 1 mV / second or less, and the hydroxy radical concentration was 0.9 × 10 ⁻⁶ mol / L.
The supply operation of the ultrapure water 2 and the water-soluble organic substance 5 was performed until 30 minutes after 110 minutes from the start of the experiment, but the operation of the ozonizer 3 and the light emission of the low-pressure mercury lamp were stopped to produce the cleaning liquid D1. Cleaning evaluation was performed. The ozone concentration was 0 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 0 mV / second, and the hydroxy radical concentration was 0 mol / L.
The evaluation results are shown in FIGS. 2 (A) and 2 (B). FIG. 2B is an enlarged view of FIG. 2A and 2B, the vertical axis indicates the peak value of the number of contaminant particles removed by the cleaning liquid B2.

(Experimental example 2)
A cleaning liquid A2 was produced and evaluated for cleaning by the same method as the cleaning liquid A1 in Experimental Example 1 until 20 minutes passed from the start of the experiment. The ozone concentration was 0 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 0 mV / second, and the hydroxy radical concentration was 0 ppm.
The operation of supplying the ultrapure water 2 and the water-soluble organic substance 5 and the operation of the ozonizer 3 were performed until 60 minutes after the start of the experiment, but the emission of the low-pressure mercury lamp was stopped to produce the cleaning liquid B2. Cleaning evaluation was performed. The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the oxidation-reduction potential was 1 mV / second or less, and the hydroxy radical concentration was 0.9 × 10 ⁻⁶ mol / L.
From 80 minutes after the start of the experiment, until 30 minutes have passed, the operation of supplying the ultrapure water 2 and the water-soluble organic substance 5, the operation of the ozonizer 3, and the light emission of the low-pressure mercury lamp were performed to produce the cleaning liquid C2, and the cleaning evaluation was performed. . The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 1 mV / second or less, and the hydroxy radical concentration was 3.0 × 10 ⁻⁶ mol / L.
A cleaning solution D2 was produced and evaluated for cleaning by the same method as the cleaning solution D1 in Experimental Example 1 until 30 minutes passed from 110 minutes after the start of the experiment. The ozone concentration was 0 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 0 mV / second, and the hydroxy radical concentration was 0 mol / L.
The evaluation results are shown in FIGS. 3 (A) and 3 (B). FIG. 3B is an enlarged view of FIG. 3A and 3B, the vertical axis indicates the peak value of the number of contaminant particles removed by the cleaning liquid B2.

(Experimental example 3)
A cleaning solution was produced in the same manner as in Experimental Example 2, and cleaning evaluation was performed.
The evaluation results are shown in FIGS. 4 (A) and 4 (B). FIG. 4B is an enlarged view of FIG. 4A and 4B, the vertical axis of the number of contaminant particles removed by the cleaning liquid B2 is shown as 1.

(Experimental example 4)
The operation of supplying the ultrapure water 2 was performed until 20 minutes passed from the start of the experiment, but the operation of supplying the water-soluble organic matter 5, the operation of the ozonizer 3, and the light emission of the low-pressure mercury lamp were stopped to produce the cleaning liquid A4. Cleaning evaluation was performed. The ozone concentration was 0 ppm, the water-soluble organic substance concentration was 0 ppm, the reduction rate of the redox potential was 0 mV / second, and the hydroxy radical concentration was 0 mol / L.
The operation of supplying the ultrapure water 2 and the operation of the ozonizer 3 were performed until 20 minutes after the start of the experiment, but the operation of supplying the water-soluble organic substance 5 and the light emission of the low-pressure mercury lamp were stopped, and the cleaning liquid B4 was removed. Manufactured and evaluated for cleaning. The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 0 ppm, the reduction rate of the oxidation-reduction potential was 1 mV / sec or less, and the hydroxy radical concentration was 0.7 × 10 ⁻⁶ mol / L.
The operation of supplying the ultrapure water 2, the operation of the ozonizer 3, and the light emission of the low-pressure mercury lamp were performed until 80 minutes after the start of the experiment, but the supply of the water-soluble organic substance 5 was stopped to produce the cleaning liquid C4. Then, cleaning evaluation was performed. The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 0 ppm, the reduction rate of the oxidation-reduction potential was 1 mV / sec or less, and the hydroxy radical concentration was 1.5 × 10 ⁻⁶ mol / L.
Until the elapse of 30 minutes after 110 minutes from the start of the experiment, the operation of supplying the ultrapure water 2 and the water-soluble organic substance 5, the operation of the ozonizer 3, and the light emission of the low-pressure mercury lamp were performed to produce the cleaning liquid D4 and evaluated the cleaning. . The ozone concentration was 4 ppm, the water-soluble organic substance concentration was 1 ppm, the reduction rate of the redox potential was 1 mV / second or less, and the hydroxy radical concentration was 3.0 × 10 ⁻⁶ mol / L.
The evaluation results are shown in FIGS. 5 (A) and 5 (B). FIG. 5B is an enlarged view of FIG. Note that the vertical axis of FIGS. 5A and 5B indicates 1 as the peak value of the number of contaminant particles removed by the cleaning liquid B4.

  From FIG. 2 (A) and FIG. 2 (B), when the cleaning liquid B1 obtained by adding the water-soluble organic substance, ozone treatment and UV treatment is used, the cleaning liquid A1 which has not been subjected to the ozone treatment and UV treatment can be used. Obviously, contaminants that could not be removed can be removed.

  From FIGS. 3 (A) and 3 (B), and FIGS. 4 (A) and 4 (B), when the cleaning liquid C2 obtained by performing water-soluble organic substance addition, ozone treatment and UV treatment is used, ozone treatment and It is clear that contaminants that could not be removed even using the cleaning liquid A2 that was not subjected to UV treatment or the cleaning liquid B2 that was not subjected to UV treatment could be removed.

  From FIG. 5 (A) and FIG. 5 (B), when the cleaning liquid C4 obtained by performing the ozone treatment and the UV treatment is used, the cleaning liquid A4 and the UV treatment not subjected to the addition of the water-soluble organic substance, the ozone treatment and the UV treatment are used. It is clear that the contaminants that could not be removed using the cleaning liquid B4 that was not performed can be removed. Furthermore, when the cleaning liquid D4 obtained by performing water-soluble organic substance addition, ozone treatment and UV treatment is used, contaminants that could not be removed using the cleaning liquid C4 without water-soluble organic substance addition can be removed. It is clear that the substance removal effect is further improved.

(Experimental example 5)
While dissolving ozone at a concentration of 8 ppm with an ozonizer in ultrapure water (electric resistivity 18 MΩ · cm), iso-propanol (aqueous solution of ultrapure water; concentration 1000 ppm) as a water-soluble organic substance is adjusted to a concentration of 10 ppm. Added. Thereafter, the obtained ozone water was quickly irradiated with ultraviolet rays at 0.3 W / L for 20 seconds with a low-pressure mercury lamp to obtain a cleaning liquid X1. Changes over time in the hydroxy radical concentration and ozone concentration in the cleaning liquid X1 were traced immediately after UV irradiation and are shown in FIGS. 6 and 7, respectively.

  A cleaning liquid X2 was obtained by the same method as the manufacturing method of the cleaning liquid X1, except that no ultraviolet irradiation was performed. Changes over time in the hydroxy radical concentration and ozone concentration in the cleaning liquid X2 were traced immediately after the addition of iso-propanol, and are shown in FIGS. 6 and 7, respectively. In addition, about the washing | cleaning liquid X2, after adding iso-propanol, the ultraviolet-ray was irradiated by 0.3 W / L for 20 second with the low pressure mercury lamp 180 second after.

  A cleaning liquid X3 was obtained by the same method as the manufacturing method of the cleaning liquid X1, except that ultraviolet irradiation was not performed. Changes over time in the hydroxy radical concentration and ozone concentration in the cleaning liquid X3 were traced immediately after the addition of iso-propanol, and are shown in FIGS. 6 and 7, respectively. As a result, it was found that the hydroxyl radical concentration after 360 seconds showed a higher concentration when irradiated with ultraviolet rays after 180 seconds than when irradiated with ultraviolet rays first. From this, for example, when it takes time to supply ozone water from the ozone water production apparatus to each cleaning tank, such as when supplying ozone water from one ozone water production apparatus to a plurality of cleaning tanks, It can be said that performing the ultraviolet irradiation step in the vicinity of each cleaning tank is a preferable method for improving the cleaning effect.

It is a schematic diagram of an example of the washing | cleaning apparatus which employ | adopted the washing | cleaning method of this invention. (A) And (B) is a graph which shows the experimental result performed in Experimental example 1. FIG. (A) And (B) is a graph which shows the experimental result performed in Experimental example 2. FIG. (A) And (B) is a graph which shows the experimental result performed in Experimental example 3. FIG. (A) And (B) is a graph which shows the experimental result performed in Experimental example 4. FIG. 6 is a graph showing temporal changes in hydroxy radical concentrations of various cleaning liquids obtained in Experimental Example 5. 6 is a graph showing changes over time in ozone concentrations of various cleaning liquids obtained in Experimental Example 5.

Explanation of symbols

  1: ozone dissolving device, 2: pure water, 3: ozonizer, 4: oxygen cylinder, 5: water-soluble organic substance, 6: ultraviolet irradiation treatment tank, 7: means for contacting the cleaning liquid with the object to be cleaned, 11: pump, 12 : 13:15: pipeline, 21: ozone concentration meter, 23: oxidation-reduction potentiometer.

Claims (18)

  A cleaning method comprising: irradiating ozone water in which ozone and a water-soluble organic substance are dissolved in pure water with ultraviolet rays to obtain a cleaning liquid, and then bringing the cleaning liquid into contact with an object to be cleaned.   The cleaning method according to claim 1, wherein the ozone reaction rate constant of the water-soluble organic material is 10 L / mol / sec or less.   The cleaning method according to claim 1 or 2, wherein the content of the water-soluble organic substance in the ozone water is 0.001 to 10 ppm.   The cleaning method according to any one of claims 1 to 3, wherein the water-soluble organic substance is selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, and t-butanol.   The cleaning method according to claim 1, wherein the water-soluble organic substance is isopropanol.   The cleaning method according to claim 1, wherein the pure water is ultrapure water having an electric resistivity of 17 MΩ · cm or more.   The cleaning method according to any one of claims 1 to 6, wherein the object to be cleaned is an electronic component or a component used in a manufacturing apparatus or a cleaning apparatus thereof. Ultraviolet irradiation treatment tank for obtaining cleaning liquid by irradiating ozone water in which ozone and water-soluble organic substance are dissolved in pure water to obtain cleaning liquid, and for bringing the cleaning liquid obtained in the ultraviolet irradiation treatment tank into contact with the object to be cleaned A cleaning device comprising means.   The cleaning apparatus according to claim 8, wherein an ozone reaction rate constant of the water-soluble organic substance is 10 L / mol / sec or less.   The cleaning apparatus according to claim 8 or 9, wherein the content of the water-soluble organic substance in the ozone water is 0.001 to 10 ppm.   The cleaning apparatus according to any one of claims 8 to 10, wherein the water-soluble organic substance is selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, and t-butanol.   The washing apparatus according to any one of claims 8 to 10, wherein the water-soluble organic substance is isopropanol.   The cleaning apparatus according to any one of claims 8 to 12, wherein the pure water is ultrapure water having an electric resistivity of 17 MΩ · cm or more.   The cleaning apparatus according to any one of claims 8 to 13, wherein the object to be cleaned is an electronic part or a part used in a manufacturing apparatus or a cleaning apparatus thereof. 2. A cleaning liquid in which ozone water in which ozone and a water-soluble organic substance are dissolved in pure water is irradiated with ultraviolet rays to obtain and contain hydroxy radicals is obtained, and then the cleaning liquid is brought into contact with an object to be cleaned. The washing | cleaning method in any one of -7. The cleaning method according to claim 1, wherein the time until the cleaning liquid is brought into contact with an object to be cleaned can be up to 360 seconds after the cleaning liquid is obtained. Ultraviolet irradiation treatment tank for obtaining a cleaning liquid in which ozone water in which ozone and a water-soluble organic substance are dissolved in pure water is irradiated with ultraviolet rays to generate and contain hydroxy radicals, and the cleaning liquid obtained in the ultraviolet irradiation processing tank The cleaning apparatus according to claim 8, further comprising means for bringing into contact with an object to be cleaned. The cleaning apparatus according to any one of claims 8 to 14 and claim 17, wherein a time until the cleaning liquid is brought into contact with an object to be cleaned after the cleaning liquid is obtained can be up to 360 seconds.

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