KR100979568B1 - Ultrasonic precision cleaning apparatus - Google Patents

Abstract

PURPOSE: An ultrasonic wave precision cleaning device is provided to generate uniform sound pressure on a wide area and prevent the concentration of the sound pressure by forming a vertical hole in the center of an ultrasound transmitter or piezoelectric device. CONSTITUTION: A cleaning solution supplying unit supplies a cleaning solution to an object. A piezoelectric element(21) is comprised of ceramic and upper and lower electrodes deposited on the upper and lower sides of the ceramic. An ultrasonic transmitter(22) is combined with the end of the piezoelectric device and transmits the ultrasonic wave generated from the piezoelectric device to the object. A vibrator(2) is comprised of a housing and a power line. The piezoelectric device is formed on the vertical hole. At least two piezoelectric devices or more included in the ultrasonic transmitter are driven at different frequencies.

Description

Ultrasonic Precision Cleaner {ULTRASONIC PRECISION CLEANING APPARATUS}

The present invention relates to an ultrasonic cleaning device, and more particularly, to maintain a uniform sound pressure over a large area without concentrating sound pressure at the center of the piezoelectric element, thereby improving cleaning efficiency without damaging the object to be cleaned. It relates to an ultrasonic cleaning device.

One of the most basic techniques in the semiconductor manufacturing process is the cleaning technique.

The semiconductor manufacturing process goes through several steps to form the surface of the wafer. In the process of each step, various kinds of contaminants are generated and remain on the semiconductor wafer and the semiconductor manufacturing equipment and are formed on the wafer by the remaining contaminants. Defects occur in the device pattern to be used, which in turn lowers the reliability of the device.

Therefore, semiconductor wafers and semiconductor manufacturing equipment have to be cleaned by physical and chemical methods in each process step to remove contaminants.

The chemical cleaning method removes surface contamination by washing with water, etching, and a redox reaction, and uses various chemicals and gases.

The physical cleaning method is to remove the deposit by ultrasonic energy, to brush off, or to remove the deposit using high pressure water.

In general, an ultrasonic cleaning method such as an appropriate combination of a physical method and a chemical method is applied for an efficient cleaning method.

That is, ultrasonic cleaning is to remove contaminants attached to the object to be cleaned using physical (ultrasound) and chemical means (chemical cleaning solution), and to prevent the removed contaminants from reattaching.

Physical phenomena by ultrasonic waves means cavitation of ultrasonic waves. Cavitation is a phenomenon in which micro bubbles are generated and extinguished by ultrasonic pressure when energy of ultrasonic waves is transferred to a liquid. Hundreds of atmospheres at tens of atmospheres) and high temperatures (hundreds of thousands to thousands).

This cavitation generates shock waves in a very short time (from tens of thousands to hundreds of thousands of seconds) and generates shock waves within a short time until the inner parts of the object contained in the liquid are not visible by the shock waves. Cleaning is done.

In practice, in addition to the impact energy due to cavitation, the stirring effect due to the radial pressure of the ultrasonic wave itself, the thermal action, and the like synergize with the detergent to achieve a high cleaning effect.

Ultrasonic cleaning is mainly used for cleaning or rinsing objects to be cleaned, such as glass substrates for liquid crystal display (LCD) devices, semiconductor wafers, magnetic disks for data storage, and the like.

The technology for such ultrasonic cleaning has been disclosed under the title of "Ultrasonic Cleaning Device" of Korean Patent Application No. 2006-0102511 filed by the present applicant.

This technique comprises a cleaning liquid supply device 100 and a vibrator 200, as shown in Figs.

Here, the cleaning liquid supply device 100 is provided above the object to be cleaned 300 so as to maintain a predetermined gap with the object to be cleaned 300, and supplies the cleaning liquid 110 to the object to be cleaned 300.

The vibrator 200 is provided to face the object to be cleaned 300 to generate ultrasonic waves, and the generated ultrasonic waves are transmitted to the object to be cleaned 300 through the cleaning liquid.

At this time, the vibrator 200 is configured to transmit the ultrasonic wave generated in the piezoelectric element 210 to the object to be cleaned 300 through the ultrasonic carrier 220 in the near field region as shown in FIG. 1, As shown in FIG. 2, the wavelength generated in the piezoelectric element 210 may be configured to transmit to the object to be cleaned 300 through the ultrasonic carrier 220 in the far field region.

Here, the piezoelectric element 210 is to vibrate by the power applied from the outside, the vibrator 200 is the ultrasonic carrier 220 for transmitting the ultrasonic wave generated in the piezoelectric element 210 and the piezoelectric element 210, and the piezoelectric The device 210 and the ultrasonic carrier 220 are integrally coupled to the housing 230 and the piezoelectric element 210 to the power line 240 for applying power.

According to this configuration, although a relatively uniform sound pressure distribution appears periodically according to the distance from the piezoelectric element in the near field, the distance near the near field in the far field is shown in FIG. 3. As shown, the negative pressure is concentrated in the center of the piezoelectric element so that the negative pressure is concentrated in the center of the end portion finally delivered to the object to be cleaned.

In this case, not only uniform cleaning becomes difficult to concentrate the negative pressure at the center of the end portion, but there is a problem that the pattern of the portion to be cleaned by the portion where the negative pressure is concentrated is damaged.

In order to prevent damage of such a pattern, the lower the sound pressure, the lower the cleaning efficiency is.

On the other hand, conventional ultrasonic cleaning apparatus has a disadvantage that can not effectively remove the foreign matter of various sizes.

4 is a graph showing the cleaning efficiency according to the general frequency and the size of particle contaminants. At 1 MHz, the cleaning efficiency of the large particle contaminants is high and the cleaning efficiency of the small particle contaminants is low, but the cleaning efficiency of the large particle contaminants is low. The cleaning efficiency of small particle contaminants is high.

That is, at low frequencies with long wavelengths, large cavities are generated and the number of cavities is small, so that large particle contaminants can be cleaned well, but small particle contaminants having a large number of contaminants are not.

On the other hand, at high frequencies with short wavelengths, many small cavitations occur. At this time, the shock wave is weak, so that small particles are cleaned well, while large particles are not washed well.

Accordingly, the conventional apparatus applying a single frequency has a disadvantage in that it is difficult to expect efficient cleaning of contaminants having different particle sizes.

A method for solving the disadvantage of low cleaning efficiency when applying such a single frequency has been disclosed in Japanese Patent No. 3917936 entitled "Short leaf cleaning device and cleaning method".

In Japanese Patent No. 3917936, "Short leaf cleaning apparatus and cleaning method" includes a rotary table 600 having an upper portion of a support member formed on a disc as shown in FIG. 5, and includes a plurality of ultrasonic vibrators 700. It arrange | positions in parallel in the longitudinal direction from the center of a rotating table to the periphery, and makes each ultrasonic vibrator 700 drive at a different frequency.

That is, this technique is to efficiently clean different particle contaminants by arranging ultrasonic vibrators having a rectangular parallelepiped shape which is driven at different frequencies and long in the radial direction of the wafer (W).

However, according to this technique, since the length of the ultrasonic vibrator is long in the radial direction, a transverse wave occurs in the longitudinal direction and the peak sound pressure appears, so that the sound pressure distribution is uneven.

As a result, there is a problem that the fine pattern is damaged by the peak sound pressure, and when the vibration is weakened in order to reduce the peak sound pressure, there is a disadvantage in that the cleaning is not performed efficiently.

In addition, despite the non-uniform sound pressure distribution, the non-uniform sound pressure distribution cannot be improved because the ultrasonic vibrator is a fixed method rather than a scanning method.

An object of the present invention for solving the problems of the background art, the cleaning device for supplying the cleaning liquid to the object to be cleaned and the ultrasonic wave generated from the piezoelectric element to the supplied cleaning liquid through the ultrasonic carrier, the piezoelectric constituting the vibrator The present invention provides an ultrasonic precision cleaning device that can form a vertical hole in the center of an element or an ultrasonic carrier so that sound pressure can be generated uniformly over a large area without being concentrated.

In addition, the present invention is to provide an ultrasonic precision cleaning apparatus for uniform cleaning of the entire area of the rotating wafer by performing the cleaning while moving the vibrator on the rotating wafer in a scanning manner.

In addition, another object of the present invention is to increase the cleaning efficiency for contaminants having various particle sizes by applying ultrasonic waves to at least two different frequencies to be cleaned using a vibrator driven at different frequencies. An ultrasonic precision cleaning device is provided.

The ultrasonic precision cleaning device of the present invention for solving the above problems comprises a cleaning liquid supply device for supplying a cleaning liquid to the object to be cleaned, a piezoelectric element configured to generate ultrasonic waves by ceramic and electrodes deposited on upper and lower surfaces of the ceramic, and the An ultrasonic cleaning device including an ultrasonic wave carrier coupled to an end of a piezoelectric element and provided to face the object to be cleaned and transferring ultrasonic waves generated from the piezoelectric element to the object to be cleaned, which is perpendicular to the center of the piezoelectric element or the ultrasonic carrier. Holes are formed.

The present invention has the advantage of increasing the cleaning efficiency by forming a vertical hole in the center of the ultrasonic carrier or the piezoelectric element to distribute the high sound pressure evenly in a large area around the vertical hole.

In addition, the present invention increases the cleaning efficiency for all contaminants having various particle sizes regardless of particle size by applying ultrasonic waves of one or more different frequencies to the object to be cleaned using vibrators driven at two or more different frequencies. Can be.

6 is an exploded perspective view of an ultrasonic precision cleaning device according to a first embodiment of the present invention, and the ultrasonic precision cleaning device according to the first embodiment of the present invention includes a cleaning liquid supply device 1 and a vibrator 2. do.

Here, the cleaning liquid supply device 1 is provided above the object to be cleaned 3 so as to maintain a predetermined gap with the object to be cleaned 3, and supplies the cleaning liquid 11 to the object to be cleaned 3.

The vibrator 2 is provided to face the object 3 to be cleaned to generate ultrasonic waves, and the generated ultrasonic waves are transmitted to the object 3 through the cleaning liquid.

At this time, the vibrator 2 is composed of the ultrasonic carrier 22, the piezoelectric element 21 provided in the ultrasonic carrier 22, the housing 23 and the power supply line 24, the scanning method on the wafer upper surface The entire surface of the rotating wafer is uniformly cleaned while moving.

Here, the piezoelectric element 21 vibrates by a power source applied from the outside, and is composed of the ceramics 21c and the electrodes 21a and 21b respectively deposited on upper and lower surfaces of the ceramics 21c.

The piezoelectric element 21 and the ultrasonic carrier 22 are integrally coupled to the housing 23, and a power line 24 for applying power to the piezoelectric element 21 is provided inside the housing 23.

According to a characteristic aspect of the present invention, it is preferable that the vertical hole 211 is formed in the piezoelectric element 21.

That is, as shown in FIG. 6, the vertical hole 211 may be formed to penetrate through the ceramic 21c and the upper and lower electrodes 21a and 21b of the ceramic 21c.

Alternatively, the vertical hole 211 may be formed in the shape of removing only the electrode layer except for the ceramic layer at the center of one or more of the electrodes 21a and 21b of the upper electrode and the lower electrode, as shown in FIG. 7. As shown in FIG. 8, the vertical hole 211 may be formed in the center of the upper electrode 21a except for the ceramic, or may be formed in the center of the lower electrode 21b except for the ceramic. Through this, all of the upper electrode 21a and the lower electrode 21b except for the ceramic may be formed.

As described above, according to the first embodiment of the present invention, the vertical hole 211 is formed at the center of the piezoelectric element 21 to thereby distribute the high sound pressure to the periphery of the vertical hole 211 to be cleaned through the ultrasonic carrier 22. By transferring to the water 3, the washing efficiency can be improved.

In addition, in the first embodiment of the present invention, the piezoelectric element 21 may be driven at least two different frequencies.

According to a modified embodiment of the first embodiment of the present invention, as shown in Figure 9, the piezoelectric element 21 is provided with at least two or more in the ultrasonic carrier 22, each piezoelectric element 21 is different from each other Can be driven at a frequency.

For example, the piezoelectric element may be composed of a piezoelectric element 21 driven at 1 MHz and a piezoelectric element 21 driven at 3 MHz, respectively. Each piezoelectric element 21 is shown in FIG. As shown in the figure, the piezoelectric elements 21 are disposed to be spaced apart from each other, or as shown in (b), one piezoelectric element 21 is disposed outside in an annular shape, and the other piezoelectric element 21 is circular in an annular piezoelectric shape. As shown in (c) and (d), two piezoelectric elements may be disposed to face each other at a predetermined distance from each other in a semicircular shape.

In addition, the piezoelectric element 21 may be positioned at different heights on the ultrasonic carrier 22 as shown in FIG. 11.

According to another modified embodiment of the first embodiment of the present invention as shown in Figure 12 at least two ultrasonic carriers 22, each ultrasonic carrier 22 is provided with at least one piezoelectric element (21) Each piezoelectric element 21 may be driven at a different frequency.

In addition, as illustrated in FIG. 13, each of the ultrasonic carriers 22 may have a different height.

Meanwhile, in the first embodiment of the present invention, the ultrasonic wave carrier 22 in the far field region is configured to deliver ultrasonic waves generated in the piezoelectric element 21 to the object to be cleaned, as shown in FIG. 14. It can be configured to transmit through the ultrasonic carrier in the field (near field), the configuration and modifications other than the ultrasonic carrier is the same as the first embodiment of the present invention described above, description of various embodiments thereof Is omitted.

In addition, in the first embodiment of the present invention, the vertical hole 211 is formed only at the center of the piezoelectric element 21, but according to an additional aspect, the vertical hole 221 is also formed at the center of the ultrasonic carrier 22 according to an additional aspect. ) Can be formed.

In addition, although the vertical hole 221 of the ultrasonic carrier 22 is illustrated as being formed in a portion of the upper end of the ultrasonic carrier 22, the vertical hole 221 is formed in a portion of the lower end, or is formed to vertically penetrate between the upper end and the lower end. can do.

16 is an exploded perspective view of the ultrasonic precision cleaning apparatus according to the second embodiment of the present invention.

Referring to FIG. 16, the ultrasonic precision cleaning device of the present invention includes a cleaning liquid supply device 1 and a vibrator 2.

Here, the cleaning liquid supply device 1 is provided above the object to be cleaned 3 so as to maintain a predetermined gap with the object to be cleaned 3, and supplies the cleaning liquid 11 to the object to be cleaned 3.

The vibrator 2 is provided to face the object 3 to be cleaned to generate ultrasonic waves, and the generated ultrasonic waves are transmitted to the object 3 through the cleaning liquid.

At this time, the vibrator 2 is composed of the ultrasonic carrier 22 and the piezoelectric element 21 provided in the ultrasonic carrier 22, the housing 23 and the power line 24, and moves in a scanning manner on the upper surface of the wafer. While rotating, the entire surface of the rotating wafer is uniformly cleaned.

In other words, the conventional vibrator is fixed, and it is difficult to uniformly clean the entire rotating wafer area. However, the present invention allows uniform cleaning because the vibrator is cleaned while moving the vibrator on the rotating wafer.

Here, the piezoelectric element 21 vibrates by a power source applied from the outside, and is composed of ceramics 21c and electrodes 21a and 21b respectively deposited on upper and lower surfaces of the ceramics 21c.

The piezoelectric element 21 and the ultrasonic wave carrier 22 are integrally coupled to the housing 23, and a power line 24 for applying power to the piezoelectric element 21 is provided inside the housing 23.

According to a characteristic aspect of the present invention, the ultrasonic carrier 22 is preferably formed with a vertical hole 221 at the center thereof.

That is, as the ultrasonic waves generated from the piezoelectric element 21 are concentrated at the center thereof, there is a problem of damaging or decreasing the cleaning efficiency when cleaning the micropattern, but the present invention provides a vertical hole 221 at the center of the ultrasonic carrier 22. The high sound pressure generated at the center of the piezoelectric element 21 is distributed in the periphery of the vertical hole 221 so that the area in which the high sound pressure is distributed can be widened to improve the cleaning efficiency.

In this case, although the vertical hole 221 is formed in a part of the upper end of the ultrasonic carrier 22 in FIG. 16, the vertical hole 221 is formed in a part of the lower part as shown in FIG. 17, or as shown in FIG. 18. Likewise, it may be formed to vertically penetrate between the upper end and the lower end.

Meanwhile, in the second embodiment of the present invention, the piezoelectric element 21 may be driven at at least two different frequencies.

That is, when driven at the existing single frequency, efficient cleaning of contaminants having different particle sizes is difficult, or even if driven at different frequencies, the sound pressure distribution of each point of the ultrasonic vibrator that is long in the longitudinal direction is not uniform and thus uniform cleaning. In this case, the problem of the fine pattern being damaged by the part where the peak sound pressure is hardly made or the uniform cleaning of the entire rotating wafer was difficult. However, the present invention provides a method of scanning the vibrators generating different frequencies by scanning. Ensure uniform cleaning.

In other words, in the cleaning using ultrasonic waves, since the cleaning efficiency of the large particle and the small particle contaminant differs according to the frequency, in order to increase the cleaning efficiency for both the large particle and the small particle contaminant, Different frequencies must be applied.

Accordingly, the present invention can increase the overall cleaning efficiency irrespective of the size of particle contaminants by using piezoelectric elements driven at least two or more different frequencies.

As another embodiment, as illustrated in FIG. 19, at least two piezoelectric elements 21 may be provided in the ultrasonic carrier 22, and each piezoelectric element 21 may be driven at a different frequency.

Specific examples of the shape and arrangement of the piezoelectric element may be replaced with the descriptions of FIGS. 10 and 10 described above.

Here, the piezoelectric element 21 may be located at different heights on the ultrasonic carrier 22 as shown in FIG. 20.

Alternatively, as illustrated in FIG. 21, at least two ultrasonic transmitters 22 are provided, and at least one piezoelectric element 21 is disposed in each ultrasonic carrier 22 such that each piezoelectric element 21 has a different frequency. Is driven.

As a modified embodiment of this, as illustrated in FIG. 22, each of the ultrasound carriers 22 may have different heights.

Meanwhile, in the second embodiment of the present invention, the ultrasonic carrier 22 in the far field region is configured to deliver the ultrasonic wave generated in the piezoelectric element 21 to the object to be cleaned, as shown in FIG. 23. It can be configured to deliver through the ultrasonic carrier in the field (near field), the configuration and modifications except for the ultrasonic carrier is the same as the second embodiment of the present invention described above, description of various embodiments thereof Omit it.

24 is a graph showing that the maximum sound pressure distribution is improved by the ultrasonic precision cleaning apparatus according to the present invention.

FIG. 25 is an area distribution for each section before improvement, and (b) shows an area distribution for each section after improvement, where the x-axis represents the intensity of sound pressure and the y-axis represents frequency.

Referring to this, in the case of (a), the sound pressure of 10% or less is mainly distributed, and the high sound pressure of 20% or more is partially concentrated in the center.

In the case of (b), the high sound pressure of 10% or more is distributed evenly without being concentrated in any one part.

As described above, the present invention can improve the cleaning efficiency by forming a vertical hole in the center of the ultrasonic carrier or the piezoelectric element, by widely distributing a high sound pressure around the vertical hole.

1 is a view showing the structure of a conventional ultrasonic cleaning device.

2 is a view showing another structure of a conventional ultrasonic cleaning device.

Figure 3 is a negative pressure distribution generated by the ultrasonic cleaning apparatus according to the prior art.

Figure 4 is a graph showing the cleaning efficiency according to the size of the frequency band-specific particle contaminants according to the prior art.

Figure 5 is a block diagram of the ultrasonic cleaning device using a single wafer multiple frequency according to the prior art.

6 is a block diagram of the ultrasonic precision cleaning apparatus according to the first embodiment of the present invention.

7 to 9 and 11 to 15 is a configuration diagram showing a modified embodiment of the ultrasonic precision cleaning apparatus of FIG.

FIG. 10 is a layout view of the piezoelectric element of FIG. 9. FIG.

16 is a block diagram of the ultrasonic precision cleaning apparatus according to a second embodiment of the present invention.

17 to 23 is a configuration diagram showing a modified embodiment of the ultrasonic precision cleaning apparatus of FIG.

24 is a graph showing that the maximum sound pressure distribution is improved by the ultrasonic precision cleaning apparatus according to the present invention.

25 is a sound pressure distribution diagram measuring the sound pressure generated in the ultrasonic precision cleaning apparatus according to the embodiments of the present invention.

<Description of the symbols for the main parts of the drawings>

1: cleaning liquid supply device

11: cleaning liquid

2: vibrator

21: piezoelectric element

21a: upper electrode

21b: lower electrode

21c: ceramic

211: vertical hole

22: ultrasonic carrier

221: vertical hole

23: housing

24: power line

3: to be cleaned

Claims (12)

A cleaning liquid supply device (1) for supplying a cleaning liquid to the object to be cleaned (3), Piezoelectric elements 21 composed of ceramics 21c and upper and lower electrodes 21a and 21b deposited on upper and lower surfaces of the ceramics 21c, respectively, to generate ultrasonic waves, and are coupled to ends of the piezoelectric elements 21 and are connected to the blood. An oscillator, which is provided so as to face the cleaning material 3 and transmits ultrasonic waves generated by the piezoelectric element 21 to the object to be cleaned 3, the housing 23, and the power line 24. In the ultrasonic cleaning device comprising: The piezoelectric element 21 has a vertical hole 211 is formed, The piezoelectric element 21 is provided with at least two or more in the ultrasonic carrier 22, each piezoelectric element 21 is ultrasonic precision cleaning device, characterized in that driven at different frequencies. The method of claim 1, The vertical hole (211) is an ultrasonic precision cleaning device, characterized in that formed through the ceramic (21c) and the upper and lower electrodes (21a, 21b) of the ceramic (21c). The method of claim 1, The vertical hole 211 is an ultrasonic precision cleaning device, characterized in that formed in the shape of removing only the electrode layer except the ceramic layer in the center of any one or more of the electrode (21a, 21b) of the upper electrode and the lower electrode. The method of claim 1, Ultrasonic precision cleaning device, characterized in that the vertical hole is further formed in the center of the ultrasonic carrier (22). The method of claim 4, wherein The vertical hole 221 is formed in a portion of the upper end or a portion of the lower end of the ultrasonic carrier 22, or the ultrasonic precision cleaning device, characterized in that formed to vertically penetrate between the upper end and the lower end. A cleaning liquid supply device (1) for supplying a cleaning liquid (11) to the object to be cleaned (3), Piezoelectric elements 21 composed of ceramics 21c and upper and lower electrodes 21a and 21b deposited on upper and lower surfaces of the ceramics 21c, respectively, to generate ultrasonic waves, and are coupled to ends of the piezoelectric elements 21 and are connected to the blood. An oscillator, which is provided so as to face the cleaning material 3 and transmits ultrasonic waves generated by the piezoelectric element 21 to the object to be cleaned 3, the housing 23, and the power line 24. In the ultrasonic cleaning device comprising: Ultrasonic precision cleaning device, characterized in that the vertical hole 221 is formed in the center of the ultrasonic carrier (22). The method of claim 6, The vertical hole 221 is formed in a portion of the upper end or a portion of the lower end of the ultrasonic carrier 22, or the ultrasonic precision cleaning device, characterized in that formed to vertically penetrate between the upper end and the lower end. The method according to any one of claims 1 to 7, The piezoelectric element 21 is; Ultrasonic precision cleaning device, characterized in that driven at least two or more different frequencies. delete The method of claim 1, The piezoelectric element is an ultrasonic precision cleaning device, characterized in that located on different heights on the ultrasonic carrier. The method according to any one of claims 1 to 7, The ultrasonic carrier 22 is provided with at least two, Each of the ultrasonic carriers 22 is composed of at least one piezoelectric element 21, Each of the piezoelectric elements 21 is ultrasonic precision cleaning device, characterized in that driven at different frequencies. The method of claim 11, Ultrasonic precision cleaning device, characterized in that each ultrasonic carrier 22 has a different height.

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