JPH1071375A - Washing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove the contaminant such as particles on the surface of an article to be washed by preparing a washing soln. by dissolving oxygen in pure water subjected to degassing treatment and applying ultrasonic vibration to this washing soln. to wash the article to be washed. SOLUTION: For example, when a film forming process of every kind and an etching process are successively applied to a silicon wafer to wash the silicon wafer at a time of the manufacture of a semiconductor device, at first, air in pure water is removed by degassing treatment and oxygen is dissolved in this pure water to prepare a washing soln. Oxygen is dissolved in this pure water, for example, by using a method bubbling the pure water with oxygen formed by electrolysis of water. Further, for example, hydrogen formed by the electrolysis of water may be dissolved in this washing soln. by a bubbling method or a gas-liquid contact method using hollow yarns and, furthermore, an acid such as hydrochloric acid or sulfuric acid may be added to ultra-pure water before and after oxygen is dissolved and, by this method, the pH of the washing soln. is set to 1-6. Subsequently, ultrasonic vibration is applied to this washing soln. to wash the surface of an article to be washed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cleaning method performed in a manufacturing process of a semiconductor device, a liquid crystal display device or an electronic component.

[0002]

2. Description of the Related Art For example, in the manufacture of semiconductor devices, cleaning is performed after various film forming steps on a silicon wafer and after an etching step. If metal impurities, organic substances, inorganic substances, particles, and the like are mixed in the cleaning liquid used in this cleaning step, these impurities cause secondary contamination of the wafer and cause defects.

For this reason, conventionally, pure water (ultra pure water) from which the metal impurities and the like have been removed by various methods is used as a cleaning liquid. Further, a gas such as oxygen dissolved in water is removed by degassing and used as a cleaning liquid.

In cleaning using pure water as a cleaning liquid,
When the cleaning object is provided along with the rinsing process of other chemicals or surfactants, the object to be cleaned is immersed in the cleaning tank and is washed by overflowing, or the nozzle is washed by spraying the cleaning liquid onto the object to be cleaned. That is being done. In particular, when a cleaning liquid is sprayed from a nozzle onto an object to be cleaned, the cleaning liquid is sprayed on the object to be cleaned by applying ultrasonic vibration for the purpose of improving the cleaning power and the efficiency of removing particles.

[0005]

An object of the present invention is to provide a cleaning method capable of effectively removing contaminants such as particles on the surface of an object to be cleaned.

[0006]

According to a cleaning method of the present invention, a cleaning solution is prepared by dissolving oxygen in degassed pure water, and an ultrasonic vibration is applied to the cleaning solution to clean an object to be cleaned. It is characterized by the following.

In the above-mentioned cleaning method, it is allowed to use a cleaning solution in which hydrogen is further dissolved. In the above-mentioned cleaning method, it is allowed to use a cleaning liquid to which an acid for adjusting pH is added before and after dissolving the oxygen.

Another cleaning method according to the present invention is characterized in that an object is cleaned by applying ultrasonic vibration to a cleaning solution in which nitrogen is dissolved in degassed pure water.
In still another cleaning method according to the present invention, a cleaning liquid is prepared by electrolytically treating an aqueous solution in which at least one gas selected from oxygen, nitrogen and chlorine is dissolved in pure water, and the cleaning liquid is sprayed on an object to be cleaned. It is characterized by doing.

In the above-mentioned cleaning method, the object to be cleaned can be cleaned by applying ultrasonic vibration to the cleaning liquid.
Still another cleaning method according to the present invention is a method of dissolving hydrogen in degassed pure water to prepare a cleaning solution, and applying ultrasonic vibration to the cleaning solution to wash the object to be cleaned,
The hydrogen is produced by electrolysis of water.

[0010] In the above-mentioned cleaning method, it is permitted to use a cleaning solution to which an acid for adjusting pH is added before and after dissolving the hydrogen. In the above-mentioned cleaning method, it is permissible to use a cleaning liquid in which at least one alkali agent selected from ammonium, tetramethylammonium hydroxide and choline is added in an amount of 0.1 to 1000 mmol / l after dissolving the hydrogen.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cleaning method according to the present invention will be described in detail. [Invention according to claim 1] (First step) First, gas contained in pure water is removed.
Subsequently, oxygen is dissolved in the pure water to prepare a cleaning solution.

The dissolution of oxygen in the pure water is performed, for example, by bubbling oxygen generated by electrolysis of water in pure water, or by electrolysis of water inside a hollow fiber made of a material having oxygen gas permeability. A method in which oxygen is supplied, pure water is supplied to the surface of the hollow fiber, and oxygen is dissolved in the pure water by gas-liquid contact can be adopted. By using oxygen generated by electrolysis of water as described above, it is possible to eliminate the economical problems such as replacing cylinders and installing the cylinders, such as when dissolving oxygen from oxygen cylinders. In addition to this, it is possible to prevent impurities such as anode electrolyzed water in which oxygen obtained by direct electrolysis of water is dissolved from being mixed or contaminated.

The oxygen can be dissolved in pure water up to its maximum dissolution amount (eg, about 20 ppm at 25 ° C.). The amount of dissolved oxygen dissolved in the pure water is 0.5
It is preferable that the content be not less than ppm.

In dissolving oxygen in the pure water,
For example, a dissolved oxygen detector of a diaphragm type is immersed in pure water, a pressure control valve is provided in an oxygen supply path, and the dissolved oxygen amount in the pure water is detected by the detector. The amount of dissolved oxygen in the pure water may be controlled by feedback.

In the washing liquid, hydrogen produced by, for example, electrolysis of water by a bubbling method or a gas-liquid contact method using hollow fibers is allowed to be dissolved. In the cleaning solution, an acid such as hydrochloric acid or sulfuric acid may be added to ultrapure water before and after dissolution of the oxygen. When adding such an acid, it is preferable to adjust the pH of the washing solution to 1 to 6.

(Second Step) The surface of the object to be cleaned is cleaned by applying ultrasonic vibration to the prepared cleaning liquid. Examples of the object to be cleaned include a wafer made of various materials used for a semiconductor device, a glass substrate used for a liquid crystal display device, and other electronic components.

The ultrasonic wave applied to the cleaning liquid is 20 kHz
It is preferably at least z. In order to perform cleaning by applying ultrasonic vibration to the cleaning liquid, for example, a nozzle-type ultrasonic cleaning device or a bar-type ultrasonic cleaning device incorporating a vibrator, or an ultrasonic cleaning having a cleaning tank equipped with a vibrator is used. A device is used.

According to the cleaning method of the present invention, since oxygen is dissolved in the cleaning liquid to which ultrasonic vibration is applied, the cleaning liquid adheres to the surface of the object to be cleaned as compared with the case where ultrapure water is used as the cleaning liquid. The efficiency of removing impurities, especially particles, can be significantly improved.

Conventionally, it has been thought that if a gas such as oxygen is dissolved in the cleaning solution, it is disadvantageous for the removal of contamination by ultrasonic cleaning. However, surprisingly, the cleaning solution containing oxygen is superfluous. It showed extremely high detergency in sonic cleaning. This is because, when ultrasonic vibration is applied to a cleaning solution of ultrapure water in which oxygen is dissolved, the amount of generated hydroxyl radicals (OH ^* ) is greater than when ultrasonic vibration is applied to ultrapure water in which oxygen is not dissolved. It is considered that if the object to be cleaned is treated with this cleaning liquid, particles on the surface of the object to be cleaned can be removed more efficiently.

Further, since the cleaning liquid has been degassed in advance, it is possible to prevent the ultrasonic wave from being reduced in transmission efficiency due to the bubbles and to prevent the vibrator from being damaged due to the adhesion of the bubbles to the vibrator.

Furthermore, if hydrogen is dissolved in pure water together with oxygen, the metal pattern is oxidized and corroded during cleaning even if there is a metal pattern, for example, a copper wiring layer, which is easily oxidized on the surface of the object to be cleaned. Can be suppressed.

Further, if a cleaning liquid obtained by adding an acid such as hydrochloric acid or sulfuric acid to ultrapure water before and after dissolving oxygen is used, particles on the surface of the object to be cleaned can be more effectively removed. .

[Invention according to claim 5] First, after removing gas contained in pure water, nitrogen is dissolved in the pure water by the above-described bubbling method or gas-liquid contact method to prepare a cleaning solution. Prepare. Subsequently, ultrasonic vibration, preferably 20 kHz or more, is applied to the cleaning liquid to apply, for example, a wafer made of various materials used for a semiconductor device, a glass substrate used for a liquid crystal display device, and other electronic components. Wash the object.

According to the cleaning method of the present invention, since nitrogen is dissolved in the cleaning liquid to which the ultrasonic vibration is applied, the cleaning liquid adheres to the surface of the object to be cleaned as compared with the case where ultrapure water is used as the cleaning liquid. The removal efficiency of impurities, particularly particles, can be significantly improved. Such high cleaning effect, when applying ultrasonic vibration to the cleaning solution, trace amounts of NO ₃ ^- ions, NO ₂ ^- ions are generated, they ions are believed to enhance the cleaning effect on impurities.

First, a cleaning solution is prepared by subjecting an aqueous solution in which at least one gas selected from oxygen, nitrogen and chlorine is dissolved in pure water to electrolytic treatment. Subsequently, the cleaning liquid is sprayed onto the object to be cleaned through a normal nozzle, for example, a shower nozzle to perform cleaning.

The electrolytic treatment can be performed, for example, by supplying raw material water to an electrolytic cell having an anode chamber in which an anode is disposed and a cathode chamber in which a cathode is disposed, and supplying electricity to the electrodes.

The cleaning liquid is subjected to ultrasonic vibrations, preferably 2 ultrasonic waves, using a nozzle type or bar type ultrasonic cleaning device or an ultrasonic cleaning device having a cleaning tank equipped with a vibrator.
The object to be cleaned can be cleaned by applying ultrasonic vibration of 0 kHz or more.

According to the cleaning method of the present invention, the cleaning liquid to be sprayed on the object to be cleaned is obtained by electrolytically treating an aqueous solution in which at least one gas selected from oxygen, nitrogen and chlorine is dissolved in pure water. This makes it possible to significantly improve the efficiency of removing impurities, particularly particles, attached to the surface of the object to be cleaned, as compared with the case where ultrapure water is used as the cleaning liquid. In particular, by applying ultrasonic vibration to the cleaning liquid, the cleaning power of the object to be cleaned can be further improved.

[Invention of Claim 8] First, after removing gas contained in pure water, hydrogen generated by electrolysis of water is applied to the pure water by the above-described bubbling method or gas-liquid contact method. Prepare a washing solution by dissolving nitrogen. Subsequently, ultrasonic vibration, preferably 20 kHz or more, is applied to the cleaning liquid to apply, for example, a wafer made of various materials used for a semiconductor device, a glass substrate used for a liquid crystal display device, and other electronic components. Wash the object.

The hydrogen can be dissolved in pure water up to its maximum amount (eg, about 2 ppm at 25 ° C.). The amount of dissolved hydrogen dissolved in the pure water is 0.3p
pm or more.

In dissolving hydrogen in the pure water,
For example, a dissolved hydrogen detector of a diaphragm type is immersed in pure water, a pressure control valve is provided in a supply path of oxygen, and the amount of dissolved hydrogen in the pure water is detected by the detector. The amount of dissolved hydrogen in the pure water may be controlled by feedback.

In the cleaning solution, an alkali agent may be further added before and after dissolving the hydrogen. As such an alkaline agent, for example, ammonia (NH ₄ O)
H), at least one selected from tetramethylammonium hydroxide and choline can be used. The addition amount of the alkali agent is 0.1 to 1000
It is preferable to set the amount to be mmol / liter (hereinafter, referred to as mmol / L). In the addition of such an alkali agent, if the addition amount is less than 0.1 mmol / L, it becomes difficult to sufficiently exert the effect of adding the alkali agent. On the other hand, if the amount of the alkali agent exceeds 1000 mmol / L, the surface of the object to be cleaned, for example, a silicon wafer may be roughened. A more preferable addition amount of the alkali agent is
It is 0.5 to 800 mmol / L.

According to the cleaning method of the present invention, since hydrogen is dissolved in the cleaning liquid to which the ultrasonic vibration is applied, the cleaning liquid adheres to the surface of the object to be cleaned as compared with the case where ultrapure water is used as the cleaning liquid. The efficiency of removing impurities, especially particles, can be significantly improved.

In addition, by dissolving reducing hydrogen in ultrapure water, even if a metal pattern that is easily oxidized, for example, a copper wiring layer, is present on the surface of the object to be cleaned, the metal pattern is removed during cleaning. Can be suppressed from being oxidized and corroded.

Further, by using hydrogen generated by the electrolysis of water, it is possible to solve economical problems such as replacement of cylinders and installation locations for stocking cylinders, such as when dissolving hydrogen from hydrogen cylinders. In addition to this, it is possible to prevent impurities such as cathode electrolyzed water in which hydrogen obtained by directly electrolyzing water from being dissolved from being mixed or contaminated.

Further, by using a cleaning liquid obtained by adding a predetermined amount of at least one alkaline agent selected from ammonia (NH ₄ OH), tetramethylammonium hydroxide and choline to ultrapure water before and after dissolving hydrogen (particularly after dissolving), Particles on the surface of the object to be cleaned can be more effectively removed. The cleaning liquid according to claim 8 may be used as a cleaning liquid for brush cleaning.

[0037]

Embodiments of the present invention will be described below in detail. (Example 1) First, after removing gas contained in pure water, 5 ppm and 8 ppm of oxygen generated by electrolysis of water were dissolved in the pure water by bubbling to prepare a cleaning solution. Further, polystyrene-based latex particles having an average particle diameter of 1 μm were dispersed and applied to the surface of the silicon wafer to forcibly contaminate the silicon wafer.

Next, the wafer is held on a rotatable disk, and a nozzle type ultrasonic cleaning device having a built-in vibrator is arranged so that the tip is located at a distance of 10 mm from the wafer surface. While rotating the wafer at a speed of 700 rpm, the cleaning liquid was put on the ultrasonic vibration from the ultrasonic cleaning apparatus and sprayed onto the wafer surface to perform cleaning. The sound wave vibration of the wafer 10 mm away from the nozzle was measured using a sound wave measuring device (OMP-20) using a piezoelectric element.
0; trade name of Shibaura Seisakusho Co., Ltd.). In such cleaning, the input power to the vibrator of the ultrasonic cleaning device is changed to dissolve the amount of oxygen (dissolved oxygen) in the cleaning liquid.
The cleaning effect when changing was evaluated. Figure 1 shows the results.
Shown in

As is clear from FIG. 1, the removal efficiency (cleaning effect) of the particles on the wafer surface increases in proportion to the sound pressure when the amount of dissolved oxygen in the cleaning liquid is the same, and when the sound pressure is the same. In some cases, it can be seen that the higher the dissolved oxygen amount in the cleaning solution, the higher the amount.

(Example 2) Artificial lung module (SAFE)
II; the oxygen generated by the electrolysis of water flows inside the hollow fiber constituting Polystein Co., Ltd.)
Degassed pure water was flowed over the outer surface of the module, and oxygen was dissolved in the pure water to prepare a cleaning solution.

The obtained cleaning liquid was treated in the same manner as in Example 1 (ultrasonic vibration of a nozzle type ultrasonic cleaning apparatus; 1.6 MHz).
The wafer surface which was forcibly contaminated with polystyrene-based latex particles according to z) was washed. As a result, as in Example 1, a high cleaning effect was exhibited.

(Example 3) First, after removing gas contained in pure water, oxygen generated by electrolysis of water was added to the pure water by gas filling using a hollow fiber module at 20 ppm.
Dissolve and further add 2 wt% of hydrochloric acid and sulfuric acid,
A washing solution was prepared by adding wt%. Further, CuO particles having an average particle size of 2 μm were dispersed and applied to the surface of the silicon wafer to cause forced contamination (initial value of particles: 1500 particles).

Next, the wafer is held on a rotatable disk, and a nozzle type ultrasonic cleaning apparatus having a built-in vibrator is arranged so that the tip is located at a distance of 10 mm from the wafer surface. Was rotated at a speed of 700 rpm, and the cleaning liquid was sprayed onto the surface of the wafer by ultrasonic vibration of 1.6 MHz from the ultrasonic cleaning apparatus to perform cleaning for 1 minute.

For comparison, a cleaning solution containing 20 ppm of oxygen was dissolved in CuO by the same method as described above.
The silicon wafer surface contaminated with particles was cleaned.
As a result, when the cleaning liquid in which only oxygen was dissolved was used, the number of residual particles was 106, whereas when the cleaning liquid to which hydrochloric acid was added was used, the number of residual particles was 43, and sulfuric acid was added. When the cleaning liquid was used, the number of remaining particles was 56, and it was confirmed that the addition of acid showed a high cleaning effect.

Example 4 7 ppm of oxygen was dissolved in degassed pure water by bubbling, and 2 ppm of hydrogen was further dissolved to prepare a cleaning solution. Subsequently, the silicon wafer having the Cu film formed on the surface is held on a rotatable disk, and the nozzle type ultrasonic cleaning apparatus having a built-in vibrator is positioned so that the tip is located 10 mm away from the wafer surface. And while the wafer is rotated at a speed of 700 rpm, the cleaning solution is supplied from the ultrasonic cleaning device for 1.5 times.
The wafer was sprayed on the surface of the wafer with ultrasonic vibration of MHz to perform cleaning for 5 minutes.

As a result, the wafer surface could be cleaned well, and there was no chipping due to local corrosion of the Cu film. For comparison, a cleaning liquid obtained by dissolving 3 ppm of oxygen in degassed pure water by bubbling was applied to a 1.5 MHz ultrasonic vibration from a nozzle type ultrasonic cleaning apparatus on a silicon wafer having a Cu film formed on a surface thereof. Injection was performed for 5 minutes for cleaning. As a result, chipping due to local corrosion of Cu was observed.

Example 5 Nitrogen was added to degassed pure water at 3 pp.
m was dissolved to prepare a washing solution. In addition, polystyrene-based latex particles having an average particle size of 1 μm were dispersed and applied to the surface of the silicon wafer to cause forced contamination (initial value of particles: 1500).

Next, the above-mentioned wafer is held on a rotatable disk, and a nozzle type ultrasonic cleaning apparatus having a built-in vibrator is arranged so that its tip is located at a distance of 10 mm from the wafer surface. Was rotated at a speed of 700 rpm, and the cleaning liquid was sprayed onto the surface of the wafer by ultrasonic vibration of 1.6 MHz from the ultrasonic cleaning apparatus to perform cleaning for 1 minute.

For comparison, the surface of the wafer which had been forcibly contaminated was cleaned by using ultrapure water as a cleaning liquid in the same manner as described above. As a result, when the ultrapure water was used as the cleaning liquid, the number of residual particles was 1,400, whereas in Example 5, the number of particles was 136, and it was confirmed that the cleaning effect was high.

The cleaning liquid was accommodated in a sealed container, and 1 MHz ultrasonic wave was applied to the cleaning liquid. As a result, generation of NO ₃ ⁻ ions and NO ₂ ⁻ ions was recognized. (Example 6) After each of chlorine, oxygen and nitrogen was dissolved in pure water, they were electrolyzed using an electrolyzer to prepare three types of cleaning liquids. Generation of hypochlorite ions is observed in the cleaning solution obtained by dissolving chlorine and electrolysis, and generation of ozone is observed in the cleaning solution obtained by dissolving oxygen and electrolysis. The formation of nitric acid and nitrous acid was observed in the cleaning solution obtained by dissolving nitrogen and performing electrolysis. Further, Fe fine particles and polystyrene-based latex particles having an average particle diameter of 1 μm were dispersed and applied to the surface of the silicon wafer to forcibly contaminate the silicon wafer.

Next, while holding the wafer on a rotatable disk and rotating it at a speed of 700 rpm, cleaning was performed by spraying the three types of cleaning liquids onto the wafer surface from a shower nozzle.

Further, a nozzle-type ultrasonic cleaning apparatus holding the wafer on a rotatable disk and incorporating a vibrator is disposed such that the tip is located at a distance of 10 mm from the wafer surface. While rotating the wafer at a speed of 700 rpm, the three types of cleaning liquids were applied to the wafer surface by ultrasonic vibration of 1.5 MHz from the ultrasonic cleaning apparatus to perform cleaning.

As a result, when a cleaning solution obtained by dissolving chlorine and oxygen and performing an electrolytic treatment is used, Fe fine particles and polystyrene latex particles on the wafer surface can be effectively removed without applying ultrasonic vibration. The cleaning effect was further improved by applying ultrasonic vibration. On the other hand, when the cleaning liquid obtained by dissolving nitrogen and performing the electrolytic treatment is used, the cleaning effect is increased by about 1.4% in the case of using the shower nozzle as compared with the case where ultrapure water is used as the cleaning liquid. However, by applying the ultrasonic vibration, the cleaning effect was increased to about 44%.

Example 7 First, after removing gas contained in pure water, 2 ppm of hydrogen generated by electrolysis of water was dissolved in the pure water by bubbling to prepare a cleaning solution. Further, polystyrene-based latex particles having an average particle size of 0.2 μm were dispersed and applied to the surface of the silicon wafer to forcibly contaminate the particles (initial value of particles: 20,000 particles).

Next, the wafer is held on a rotatable disk, and a nozzle type ultrasonic cleaning device having a built-in vibrator is arranged so that its tip is located at a distance of 10 mm from the wafer surface. While rotating the wafer at a speed of 700 rpm, the cleaning solution was sprayed onto the surface of the wafer by ultrasonic vibration of 1.6 MHz from the ultrasonic cleaning apparatus to perform cleaning for 1 minute.

For comparison, a cleaning solution in which 2 ppm of hydrogen was dissolved was sprayed from a shower nozzle onto the surface of the silicon wafer which had been forcibly contaminated for 1 minute to perform cleaning. As a result, when the cleaning solution in which hydrogen is dissolved is showered,
In contrast to the case where the number of residual particles was 12476, the number of residual particles was 2234 in Example 7 in which the cleaning liquid in which hydrogen was dissolved was applied by ultrasonic vibration, and the cleaning effect was high.

Example 8 First, after removing gas contained in pure water, 2 ppm of hydrogen generated by electrolysis of water was dissolved in the pure water by bubbling, and tetramethylammonium hydroxide (TMAH) was further dissolved therein. 0.05 mmol / L, 0.1 mmol / L, 10 mmol / L, 100 mmol / L and 1000 mmol / L, respectively.
Choline was added at 0.05 mmol / L and 0.1 mmol / L respectively.
L, 10 mmol, 100 mmol / L and 1000 mmol / L, and ammonia (NH ₄ OH) of 0.05
A total of 14 kinds of washing liquids were prepared by adding mmol / L, 0.1 mmol / L, 10 mmol / L and 100 mmol / L. In addition, a silicon wafer having an average particle size of 1 μm
O ₂ particles were dispersed and applied to forcibly contaminate the particles (initial value of particles: 4,600).

Next, the above-mentioned wafer is held on a rotatable disk, and a nozzle type ultrasonic cleaning apparatus having a built-in vibrator is arranged so that its tip is located at a distance of 10 mm from the wafer surface. While rotating the wafer at a speed of 700 rpm, the cleaning solution was sprayed onto the surface of the wafer by ultrasonic vibration of 1.6 MHz from the ultrasonic cleaning apparatus to perform cleaning for 1 minute.

For comparison, a cleaning solution in which 2 ppm of hydrogen was dissolved was sprayed from a shower nozzle onto the surface of the silicon wafer that had been compulsorily contaminated for 1 minute to perform cleaning. Example 8 was performed using a cleaning solution in which 2 ppm of hydrogen was dissolved.
Cleaning was performed by spraying for 1 minute on the surface of the silicon wafer that had been forcibly contaminated by the same method as described above. The number of remaining particles of the SiO ₂ particles after such washing was counted. The results are shown in Table 1 below.

[0060]

[Table 1]

As is apparent from Table 1, tetramethylammonium hydroxide, choline, and ammonia were added in predetermined amounts (0.1 to 1000 m
In the cleaning method of Example 8 using the added cleaning liquid, the particles of the SiO ₂ particles can be removed more effectively than the shower cleaning of the cleaning liquid in which hydrogen is dissolved or the high-frequency cleaning of the cleaning liquid in which hydrogen is dissolved. It can be seen that a high cleaning effect is exhibited. In addition, in the cleaning method using the cleaning liquid in which the addition amounts of tetramethylammonium hydroxide, choline, and ammonia are less than 0.1 mmol / L, the particle removal efficiency is almost the same as the high-frequency cleaning method of the cleaning liquid in which hydrogen is dissolved. The effect of the addition cannot be sufficiently exhibited.

[0062]

As described above in detail, according to the cleaning method of the present invention, it is possible to effectively remove contaminants such as particles on the surface of the object to be cleaned, and to manufacture semiconductor devices and liquid crystal display devices. It has remarkable effects such as being effectively applicable to precision cleaning in the process.

[Brief description of the drawings]

FIG. 1 shows the relationship between the sound pressure on the surface of a wafer and the particle removal rate when cleaning liquids having different dissolved oxygen amounts according to Embodiment 1 of the present invention are sprayed onto a silicon wafer which has been subjected to ultrasonic vibration and forcedly contaminated and cleaned. FIG.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Fujita 33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Inside Toshiba Production Engineering Laboratory Co., Ltd.

Claims (10)

[Claims] 1. A cleaning method comprising dissolving oxygen in degassed pure water to prepare a cleaning liquid, and applying ultrasonic vibration to the cleaning liquid to wash an object to be cleaned. 2. The cleaning method according to claim 1, wherein said oxygen is generated by electrolysis of water. 3. The cleaning method according to claim 1, wherein hydrogen is further dissolved in the cleaning liquid. 4. The cleaning method according to claim 1, wherein the pH of the cleaning solution is adjusted by further adding an acid before and after dissolving the oxygen. 5. A cleaning method comprising dissolving nitrogen in degassed pure water to prepare a cleaning liquid, and applying ultrasonic vibration to the cleaning liquid to wash an object to be cleaned. 6. A cleaning solution is prepared by electrolytically treating an aqueous solution in which at least one gas selected from oxygen, nitrogen and chlorine is dissolved in pure water, and the cleaning solution is sprayed on an object to be cleaned. Cleaning method. 7. The cleaning method according to claim 6, wherein the object to be cleaned is cleaned by applying ultrasonic vibration to the cleaning liquid. 8. A method for preparing a cleaning solution by dissolving hydrogen in degassed pure water, and applying ultrasonic vibration to the cleaning solution to clean an object to be cleaned, wherein the hydrogen is used for electrolysis of water. A cleaning method characterized by being produced by the method described above. 9. The cleaning method according to claim 8, wherein the pH of the cleaning solution is adjusted by adding an alkali agent before and after dissolving the hydrogen. 10. The method according to claim 1, wherein the alkaline agent is at least one selected from ammonium, tetramethylammonium hydroxide and choline, and the amount added is 0.1 to 1000 mmol / l. 9. The washing method according to 9.