JP4599323B2 - Ultrasonic cleaning apparatus and ultrasonic cleaning method - Google Patents

Description

  The present invention relates to an ultrasonic cleaning apparatus applied to cleaning of a semiconductor substrate, a glass substrate for liquid crystal display, an optical disk substrate, and the like, and an ultrasonic cleaning method for an object to be cleaned using the ultrasonic cleaning apparatus.

  2. Description of the Related Art Conventionally, as this type of ultrasonic cleaning apparatus, an apparatus that injects cleaning water containing dissolved gas and superposed with ultrasonic waves from a nozzle tip onto a surface to be cleaned is known (for example, a patent) Reference 1). In addition, in an ultrasonic cleaning apparatus of a type that cleans an object to be cleaned while being immersed in a cleaning tank, a so-called megasonic having a frequency of 400 KHz to 10 MHz is conventionally used as an ultrasonic wave superimposed on cleaning water containing dissolved gas. (For example, refer to Patent Document 2).

When ultrasonic waves are superimposed on the cleaning water containing dissolved gas, cavitation occurs in the cleaning water. When this cleaning water is supplied to the surface to be cleaned, the pressure generated by the high-speed flow caused by the generation and disappearance of cavities due to cavitation The fluctuation acts on the surface to be cleaned, and the object to be cleaned can be cleaned with high efficiency and high efficiency. In particular, when megasonic is used as the ultrasonic wave superimposed on the cleaning water, high-density cavitation can be generated, so that a higher cleaning effect can be obtained.
JP 2004-335525 A Japanese Patent Laid-Open No. 10-172948

  As described above, in order to generate cavitation in the wash water by applying ultrasonic waves, it is necessary to use a solution containing dissolved gas as the wash water, but if the wash water contains dissolved gas, Therefore, the ultrasonic wave is easily attenuated, and it is difficult to propagate the ultrasonic wave to the surface to be cleaned as the frequency is increased. Therefore, it is difficult to apply a large cleaning force to the surface to be cleaned. This is especially true when the ultrasonic cleaning device, in which the distance from the ultrasonic generator to the surface to be cleaned is likely to be larger than the ultrasonic cleaning device of the cleaning tank type, is superposed with megasonics that are easily attenuated in the cleaning water. Inconvenience becomes noticeable. For example, when 1 MHz ultrasonic waves are superimposed on ultrapure water containing about 10 ppm of air, the ultrasonic waves are attenuated to about 50% at a water depth of 10 cm, and about 20% are attenuated for ultrapure water containing about 20 ppm of air. To do. When supersonic water of 2 MHz is superimposed on ultrapure water containing about 10 ppm of air, the ultrasonic wave is attenuated to about 25% at a water depth of 10 cm, and is attenuated to about 5% for ultrapure water containing about 20 ppm of air. To do.

  In addition, as described in Patent Document 1, the conventional ultrasonic cleaning apparatus is configured to superimpose ultrasonic waves on the cleaning water by introducing the cleaning water containing dissolved gas into the nozzle provided with the ultrasonic vibrator. Therefore, when the ultrasonic vibrator is driven, cavitation occurs in the nozzle, and pressure fluctuation due to high-speed flow caused by generation and disappearance of the cavity generated by cavitation occurs even in the immediate vicinity of the ultrasonic vibrator. At this time, if dissolved gas is present, bubbles may accumulate on the ultrasonic vibration surface. This bubble not only makes it difficult for the ultrasonic wave to propagate, but also causes a problem that the ultrasonic transducer is easily damaged because the ultrasonic wave is reflected on the bubble and overheats.

  The present invention has been made to solve such deficiencies of the prior art, and an object of the present invention is to provide an ultrasonic cleaning apparatus that has a high cleaning effect on an object to be cleaned and is excellent in durability, and this An object of the present invention is to provide a highly efficient ultrasonic cleaning method for an object to be cleaned using an apparatus.

In order to solve the above-described problems, the present invention firstly discharges the first cleaning water on which the deaeration process is performed toward the surface to be cleaned of the object to be cleaned and the ultrasonic wave is superimposed. A second cleaning water discharge unit configured to supply a second cleaning water prepared by dissolving hydrogen, nitrogen, oxygen, air, or argon as a dissolved gas toward a surface to be cleaned of the object to be cleaned. a wash water discharge portion, and a first washing water and the second washing water to the configuration of the Ru to generate cavitation in the surface to be cleaned near in contact on the cleaned surface.

As described above, when the first cleaning water that has been deaerated and superposed with ultrasonic waves is discharged from the first cleaning water discharge section, the generation of cavities due to cavitation in the first cleaning water is suppressed, and large bubbles are generated. Therefore, the ultrasonic wave can be propagated far away and the ultrasonic vibrator provided in the first cleaning water discharge part can be prevented from being damaged. Moreover, the 2nd cleaning water which discharges the 2nd cleaning water containing dissolved gas from the 2nd cleaning water discharge part, the 2nd cleaning water containing dissolved gas and the 1st cleaning water with which the ultrasonic wave was superimposed on the surface to be cleaned Since the first washing water and the second washing water are mixed with each other and cavitation can be generated in the mixed water at a high density, the object to be washed can be washed with high efficiency and high efficiency. In addition, the first cleaning water is supplied after flowing the second cleaning water in the vicinity of the surface to be cleaned, and the first cleaning water and the second cleaning water are flown in layers without being mixed. Also, the ultrasonic wave can be propagated far away, and cavitation can be generated with high density in the second cleaning water near the surface to be cleaned. Furthermore, when any of hydrogen, nitrogen, oxygen, air, and argon is included as a dissolved gas, a high detergency can be exhibited.

  The present invention also relates to the ultrasonic cleaning apparatus. Second, at least the first cleaning water discharge portion of the first and second cleaning water discharge portions moves along the surface direction of the object to be cleaned. Configured to be possible.

  In this way, if the first cleaning water discharge section is configured to be movable along the surface direction of the object to be cleaned, ultrasonic waves can be uniformly propagated over a wide range of the surface to be cleaned, so that cleaning of a large area is highly efficient. Can be done.

  Further, the present invention thirdly relates to the ultrasonic cleaning apparatus, and both the first and second cleaning water discharge sections are configured to be movable along the surface direction of the object to be cleaned, The first and second cleaning water discharge portions are arranged on the surface of the object to be cleaned so that the discharge portion of the first cleaning water and the discharge portion of the second cleaning water on the surface always maintain a constant relationship. It was configured to move along the direction.

  In this way, both the first and second cleaning water discharge portions are placed on the surface of the object to be cleaned so that the first cleaning water discharge portion and the second cleaning water discharge portion always maintain a constant relationship. By moving along the direction, cavitation can be uniformly applied over a wide range of the surface to be cleaned, so that cleaning of a large area can be performed with high efficiency and high efficiency.

  Further, in the fourth aspect of the ultrasonic cleaning apparatus, only the first cleaning water discharge section is configured to be movable along the surface direction of the object to be cleaned, from the second cleaning water discharge section. The second cleaning water to be discharged is discharged to the center portion of the surface to be cleaned, and the first cleaning water discharge portion is moved along the surface direction of the object to be cleaned.

  Also in this case, since cavitation can be applied uniformly over a wide range of the surface to be cleaned, large area cleaning can be performed with high efficiency and high efficiency.

  In the fifth aspect of the present invention, the ultrasonic cleaning apparatus is configured such that the frequency of the ultrasonic wave superimposed on the first cleaning water is 400 KHz to 10 MHz.

  When ultrasonic waves having a frequency of 400 KHz to 10 MHz, that is, megasonic, are superimposed on the cleaning water containing dissolved gas, cavitation can be generated at high density in the cleaning water, so that a high cleaning effect can be exhibited.

In the sixth aspect of the present invention, the ultrasonic cleaning apparatus is configured such that the second cleaning water is adjusted to be alkaline.

  When the second cleaning water is adjusted to be alkaline, it is possible to prevent the particles removed from the object to be cleaned from reattaching to the object to be cleaned, and a high cleaning effect can be obtained.

  Further, according to the present invention, seventhly, with respect to the ultrasonic cleaning apparatus, the cleaning object holding unit is provided with a rotation driving unit.

  When the object to be cleaned is provided with a rotation drive unit and the object to be cleaned held by the object to be cleaned is driven to rotate, the first and second cleaning water supplied on the object to be cleaned is subjected to centrifugal force. Since it can be made to flow uniformly in the outer peripheral direction of the cleaning object, a higher cleaning power can be exhibited over the entire surface of the object to be cleaned.

On the other hand, the present invention relates to an ultrasonic cleaning method, wherein the first cleaning water that has been degassed and superposed with ultrasonic waves , and any one of hydrogen, nitrogen, oxygen, air, and argon is prepared as a dissolved gas. The second cleaning water is brought into contact with the surface to be cleaned and the surface to be cleaned is cleaned by generating cavitation in the vicinity of the surface to be cleaned.

  When the first cleaning water that has been deaerated and superposed with ultrasonic waves is supplied to the surface to be cleaned, and the second cleaning water containing dissolved gas is supplied to the surface to be cleaned The first and second cleaning waters are mixed on the surface to be cleaned. Since the dissolved gas is degassed in the first cleaning water, the ultrasonic wave superimposed on the first cleaning water is propagated far without being attenuated. Therefore, cavitation can be generated at a high density on the surface to be cleaned, and the surface to be cleaned can be cleaned with high efficiency. Also, the first cleaning water is supplied after flowing the second cleaning water in the vicinity of the surface to be cleaned, and the first cleaning water and the second cleaning water are not mixed and flowed in layers. Sound waves can be propagated far away, and cavitation can be generated at high density in the second cleaning water near the surface to be cleaned.

  According to the present invention, the first cleaning water that has been deaerated and superposed with ultrasonic waves is discharged from the first cleaning water discharge section, and the second cleaning water containing dissolved gas is discharged to the second cleaning water. Since the first cleaning water discharged from the discharge unit and superposed with ultrasonic waves on the surface to be cleaned is mixed with the second cleaning water containing dissolved gas, the first cleaning water and the second cleaning water Cavitation can be generated at high density in the mixed water, and the object to be cleaned can be cleaned with high efficiency and high efficiency. Further, since cavitation hardly occurs in the first washing water, it is possible to prevent the ultrasonic vibrator provided in the first washing water discharge unit from being damaged.

  Hereinafter, embodiments of an ultrasonic cleaning apparatus and an ultrasonic cleaning method according to the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a configuration diagram of the ultrasonic cleaning apparatus according to the first embodiment, FIG. 2 is an operation explanatory diagram of the ultrasonic cleaning apparatus according to the first embodiment, and FIG. 3 is an operation of the ultrasonic cleaning apparatus according to the second embodiment. It is explanatory drawing.

  As shown in FIG. 1, the ultrasonic cleaning apparatus according to the first embodiment includes an object holding unit 1 that detachably holds an object A to be cleaned, and a rotational drive that rotationally drives the object holding unit 1. The first cleaning water 3 that has been deaerated and superposed with ultrasonic waves is directed toward the cleaning surface B of the cleaning object A held by the cleaning unit 2 and the cleaning object holding unit 1. The cleaning water discharge unit 4 and the second cleaning water discharge unit 6 for supplying the second cleaning water 5 containing dissolved gas toward the surface B to be cleaned of the object A to be cleaned.

  The object-to-be-cleaned holding unit 1 is provided with chucking means (not shown), and the object to be cleaned A is stably and detachably held. A rotary motor is used as the rotation drive unit 2 of the cleaning object holding unit 1. In addition, when the to-be-cleaned object A is small, the rotation drive part 2 can also be abbreviate | omitted.

  Ultrapure water supplied from the ultrapure water supply source 11 and degassed by the gas deaeration unit 12 is introduced into the first cleaning water discharge unit 4. The first cleaning water discharge unit 4 includes an ultrasonic vibrator 13 and superimposes 400 KHz to 10 MHz ultrasonic waves on the introduced ultrapure water. As shown in FIG. 1, the first cleaning water 3 that has been deaerated and superposed with ultrasonic waves is directed from the tip of the first cleaning water discharge unit 4 toward the surface B to be cleaned. Discharged.

  The second cleaning water discharge unit 6 includes ultrapure water supplied from the ultrapure water supply source 11, dissolved gas supplied from the dissolved gas supply source 14, and ammonia water supplied from the ammonia water supply source 15. Are prepared in the preparation unit 16 and the amount of dissolved gas in the washing water is adjusted to a predetermined value, for example, 10 ppm to 20 ppm for nitrogen, 1.0 ppm to 3.0 ppm for hydrogen, and the pH is adjusted to 8.5 to 11 Conditioned wash water is introduced. As the dissolved gas, any gas such as an inert gas such as nitrogen gas, oxygen gas or hydrogen gas can be used, but hydrogen gas is most preferable because of its high detergency. When the concentration of hydrogen gas is less than 1.0 ppm, the cleaning power is not sufficient, and in order to exceed 3.0 ppm, hydrogen must be dissolved and supersaturated at a high pressure, resulting in a larger apparatus and lower efficiency. To do. The pH of the solution may be alkaline, but is preferably in the range of 8.5-11. If it is less than 8.5, the effect of preventing re-adhesion is reduced, and if it exceeds 11.0, the load of rinsing increases because the alkali concentration is high. As a substance to be added for alkalinity, ammonia can be suitably used because no solid precipitates during drying.

  In the ultrasonic cleaning apparatus of the first embodiment, as shown in FIG. 2, the first cleaning water discharge unit 4 and the second cleaning water discharge unit 6 are along the surface direction of the object A to be cleaned. It is configured to be movable, and when the first and second cleaning water discharge portions 4 and 6 are moved, the discharge portion of the first cleaning water 3 on the surface of the object A to be cleaned and the second cleaning water 5 The discharge part always maintains a constant relationship.

  On the other hand, in the ultrasonic cleaning apparatus according to the second embodiment, as shown in FIG. 3, only the first cleaning water discharge unit 4 can move along the surface direction of the object A to be cleaned. The second cleaning water discharge unit 6 is configured to discharge the second cleaning water 5 to the center position of the object A to be cleaned. About others, it is comprised similarly to the ultrasonic cleaning apparatus of 1st Embodiment.

  In the ultrasonic cleaning apparatus according to the present invention, the object holding unit 1 to which the object A to be cleaned is attached is rotated by the rotation driving unit 2 while the first object is directed toward the surface B to be cleaned. And the to-be-cleaned surface B of the to-be-cleaned object A is ultrasonically cleaned by discharging the 2nd cleaning water 3 and 5 from the 1st and 2nd cleaning water discharge parts 4 and 6.

  Examples of the present invention will be given below to clarify the effects of the present invention.

<Example 1>
Using the ultrasonic cleaning apparatus according to the first embodiment, ultrapure water deaerated from the first cleaning water discharge unit 4 is discharged at a flow rate of 1 L / min, and hydrogen is discharged from the second cleaning water discharge unit 6. Washing water in which 2 ppm (supersaturated) and 10 ppm of ammonia (pH 10) were dissolved was discharged. As a sample for testing detergency, a glass plate having a 150 cm square side and a chromium film on the surface, and 0.5 μm-sized alumina abrasive powder adheres as contamination particles. Used. The sample was rotated at 600 rpm, and the ultrasonic vibrator was driven with a main frequency of 1.5 MHz and an output of 48 W. While supplying the cleaning water discharged from the second cleaning water discharge unit 6 to the center of the sample, the first cleaning water discharge unit 4 reciprocated once in 5 seconds from the center of the sample to the end. As a result, the number of 56,900 contaminated particles adhering to the sample before the test became 5, and it was found that almost 100% of the contaminated particles could be removed in 5 seconds. Similar results were obtained when the ultrasonic cleaning apparatus according to the second embodiment was used. On the other hand, when supersonic waves with a main frequency of 1.5 MHz and an output of 48 W are superimposed on cleaning water containing 2 ppm of dissolved hydrogen gas and 10 ppm of ammonia, the number of contaminated particles of 55700 adhered to the sample before the test. Was only 32460 in 5 seconds, and the removal rate of contaminating particles was 40%.

<Example 2>
Using the ultrasonic cleaning apparatus according to the first embodiment, ultrapure water deaerated from the first cleaning water discharge unit 4 is discharged at a flow rate of 1 L / min, and hydrogen is discharged from the second cleaning water discharge unit 6. Washing water in which 2 ppm (supersaturated) and 10 ppm of ammonia (pH 10) were dissolved was discharged. As a sample for testing detergency, a glass plate having a 150 cm square side and a chromium film on the surface, and 0.5 μm-sized alumina abrasive powder adheres as contamination particles. Used. The sample was rotated at 600 rpm, and the ultrasonic transducer was driven at a main frequency of 3.0 MHz and an output of 48 W. While supplying the cleaning water discharged from the second cleaning water discharge unit 6 to the center of the sample, the first cleaning water discharge unit 4 reciprocated once in 5 seconds from the center of the sample to the end. As a result, it was found that the number of 55800 contaminating particles adhering to the sample before the test was 10, and that almost 100% of the contaminating particles could be removed in 5 seconds. Similar results were obtained when the ultrasonic cleaning apparatus according to the second embodiment was used. On the other hand, when ultrasonic waves with a main frequency of 3.0 MHz and an output of 48 W are superposed on cleaning water containing 2 ppm of dissolved hydrogen gas and 10 ppm of ammonia, 55700 contaminated particles adhered to the sample before the test. It was hardly removed even after 60 seconds.

It is a block diagram of the ultrasonic cleaning apparatus which concerns on 1st Embodiment. It is operation | movement explanatory drawing of the ultrasonic cleaning apparatus which concerns on 1st Embodiment. It is operation | movement explanatory drawing of the ultrasonic cleaning apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Washing object holding | maintenance part 2 Rotation drive part 3 1st washing water 4 1st washing water discharge part 5 2nd washing water 6 2nd washing water discharge part A To-be-washed object B To-be-washed surface

Claims (8)

A first cleaning water discharge unit that discharges first cleaning water that has been degassed toward the surface to be cleaned and on which ultrasonic waves are superimposed, and toward the surface to be cleaned of the object to be cleaned A second wash water discharge section for supplying a second wash water prepared by dissolving any one of hydrogen, nitrogen, oxygen, air, and argon as a dissolved gas, and the first wash water and the second wash It said the water is contacted on the cleaned surface ultrasonic cleaning apparatus according to claim Rukoto to generate cavitation in the cleaned surface vicinity.   2. The super-type according to claim 1, wherein at least the first cleaning water discharge portion among the first and second cleaning water discharge portions is movable along a surface direction of the object to be cleaned. Sonic cleaning device.   Both the first and second cleaning water discharge portions are configured to be movable along the surface direction of the object to be cleaned, and the first cleaning water discharge part and the second on the surface of the object to be cleaned 3. The first and second cleaning water discharge portions are moved along the surface direction of the object to be cleaned so as to always maintain a constant relationship with the cleaning water discharge portion. The ultrasonic cleaning apparatus as described.   Only the first cleaning water discharge portion is configured to be movable along the surface direction of the object to be cleaned, and the second cleaning water discharged from the second cleaning water discharge portion is disposed on the surface to be cleaned. 2. The ultrasonic cleaning apparatus according to claim 1, wherein the ultrasonic cleaning apparatus moves to the central portion and moves the first cleaning water discharge portion along a surface direction of the object to be cleaned.   The ultrasonic cleaning apparatus according to claim 1, wherein the frequency of the ultrasonic wave superimposed on the first cleaning water is 400 KHz to 10 MHz. The ultrasonic cleaning apparatus according to claim 1, wherein the second cleaning water is adjusted to be alkaline . The ultrasonic cleaning apparatus according to claim 1, further comprising an object holding unit that detachably holds the object to be cleaned, and a rotation drive unit included in the object holding unit . The first cleaning water that has been degassed and superposed with ultrasonic waves, and the second cleaning water in which any one of hydrogen, nitrogen, oxygen, air, and argon is prepared as a dissolved gas are mixed with the object to be cleaned. An ultrasonic cleaning method comprising: cleaning a surface to be cleaned by contacting the surface to be cleaned and generating cavitation in the vicinity of the surface to be cleaned .

Images