KR101002706B1 - Ultrasonic cleaning apparatus - Google Patents

Abstract

The present invention prevents reflection in the progress of the ultrasonic wave generated in the piezoelectric element to efficiently deliver the ultrasonic wave and to uniformly distribute the sound pressure generated at the final end to increase the cleaning efficiency without damaging the object to be cleaned. It relates to an ultrasonic cleaning device.

Ultrasonic cleaning device of the present invention for this purpose is a cleaning liquid supply device for supplying a cleaning liquid to the object to be cleaned, an ultrasonic transducer and a piezoelectric element provided in the ultrasonic carrier and provided to face the object to be cleaned, the vibrator for generating ultrasonic waves An ultrasonic cleaning device comprising: the ultrasonic carrier; The diameter gradually increases from the coupling portion with the piezoelectric element toward the end portion.

Cleaner, Ultrasonic, Diameter, Carrier, Nearfield, Farfield

Description

Ultrasonic Cleaner {ULTRASONIC CLEANING APPARATUS}

The present invention relates to an ultrasonic cleaning device, and more particularly, to effectively transmit ultrasonic waves by preventing reflection in the progress of ultrasonic waves generated in a piezoelectric element, and to uniformly distribute the sound pressure generated at the final end. The present invention relates to an ultrasonic cleaning apparatus capable of increasing the cleaning efficiency without damaging the body.

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 must be cleaned at each process step by physical and chemical methods 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 peeling off the deposit by ultrasonic energy, rinsing with a brush, or removing the deposit using high pressure water.

In general, an ultrasonic cleaning method such as a method of properly combining 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 primarily used for cleaning or rinsing objects, such as glass substrates for liquid crystal display (LCD) devices, semiconductor wafers, magnetic disks for data storage, and the like.

FIG. 1 shows the structure of a conventional ultrasonic cleaning apparatus, which cleans the surface of a semiconductor wafer 105 using ultrasonic waves and cleaning water (or cleaning liquid), and is provided with a cleaning liquid 103 supplied through a supply pipe 102 on the side. ) Is sprayed through the washing water jet 106 having a nozzle structure at the bottom.

In the explanation of the operation, the cleaning liquid 103 is introduced through the supply pipe 102, and the ultrasonic wave by the vibrator 101 is sent out together with the cleaning liquid 103.

As a result, the cleaning solution 103 in which ultrasonic waves are applied to the object to be cleaned 105 positioned below the washing water jet 106 is ejected, and the surface of the object being cleaned is rotated by the rotating shaft 104. It is cleaned.

By the way, since the structure which discharge | releases the ultrasonic wave and the washing | cleaning liquid 103 previously combined in the one washing | cleaning water jet 106 is employ | adopted for the washing | cleaning apparatus of such a structure, too much washing | cleaning liquid 103 is compared with the washing | cleaning effect. ) Has been consumed.

In addition, due to the instantaneous fluctuations in the cleaning conditions such as operating frequency, cleaning water condition, power consumption, cooling condition, etc. during the cleaning operation, the variation of the ultrasonic intensity is large and the high pressure cleaning water is ejected as the nozzle structure. There have been fatal problems that result in local or overall damage to the surface.

Figure 2 shows another structure of the conventional ultrasonic cleaning apparatus, disposed so as to have a predetermined gap with the semiconductor wafer 114, the vibration rod 110 is provided to protrude forward and ultrasonic vibration energy to the vibration rod 110 The vibration unit 111 coupled to the vibration rod 110, a washing water emitter 113 for discharging the washing water 116, and a rotating plate 112 and a rotating shaft 115 for rotating the semiconductor wafer.

According to the structure, while rotating the semiconductor wafer 114, the vibration rod 110 emits longitudinal ultrasonic waves, and when the cleaning water 116 is sprayed, ultrasonic cleaning is performed over one surface of the semiconductor wafer 114.

However, in another structure of the conventional ultrasonic cleaning apparatus as shown in FIG. 2, since the vibration rod 110 having the cantilever structure is adopted, the cleaning operation proceeds only in the axial direction of the vibration rod 110. Ultrasonic strength is generated along the vibration rod 110, and thus, even cleaning performance cannot be expected in a fine pattern wafer.

Techniques for improving this problem have been disclosed under the heading of "Ultrasonic Cleaning Device" of Korean Patent Application No. 2006-0102511 filed by the present applicant.

According to this technique, by forming a vibrator having a piezoelectric element attached to one surface of the ultrasonic carrier having a near field having a straightness and a far field that is diffusion overlapping, while improving the ultrasonic transfer efficiency to the object to be cleaned while reducing damage to the object to be cleaned It is a technology to improve the cleaning efficiency.

However, in this technique, since the ultrasonic wave carrier 210 coupled to the piezoelectric element 200 has a structure in which the linear structure or the diameter is gradually reduced in the longitudinal direction at the coupling portion, the ultrasonic wave transmission efficiency decreases.

That is, the width of the ultrasonic wave generated from the piezoelectric element is reduced when the diameter of the ultrasonic carrier is gradually reduced.

In addition, when the ultrasonic carrier has a linear structure, as shown in FIG. 3, when the ultrasonic wave generated from the piezoelectric element is diffused and propagated, a part of the ultrasonic carrier hits and reflects the inner wall of the ultrasonic carrier.

As a result, the ultrasonic waves finally delivered by the reflected ultrasonic waves become non-uniform, thereby damaging the micro patterns or lowering the cleaning efficiency, which is not suitable for cleaning the micro patterns.

An object of the present invention for solving the problems of the background art, in 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 diameter of the ultrasonic carrier By increasing in the direction away from the piezoelectric element, to provide an ultrasonic cleaning device so that the ultrasonic wave generated from the piezoelectric element is not reflected on the traveling path.

In addition, an object of the present invention is to design the length of the ultrasonic carrier in the distance between the near field and the far field between the sections where the sound pressure distribution is uniform, so that the ultrasonic cleaning device to make the music distribution at the end of the ultrasonic carrier uniform. In providing.

Ultrasonic cleaning apparatus of the present invention for solving the above problems consists of a cleaning liquid supply device for supplying a cleaning liquid to the object to be cleaned, and an ultrasonic carrier and a piezoelectric element provided in the ultrasonic carrier and provided to face the object to be cleaned An ultrasonic cleaning device comprising a vibrator for generating a vibration, the ultrasonic delivery body; It is characterized in that the diameter gradually increases in the end direction from the coupling portion with the piezoelectric element.

The ultrasonic carrier may have a conical shape, a multi-stage shape, or an outer wall surface in a curved shape.

In addition, the length L of the ultrasonic carrier is preferably 0.1N to 0.8N or 2N to 100N. (N = D ² −λ ² / 4λ, where D is the width of the piezoelectric element and λ is the ultrasonic Wavelength, where N is the distance between the end of the nearfield of the ultrasound and the start of the farfield.)

In addition, it is preferable that the width W = 2 · (tanθ · L) of the end of the ultrasonic carrier. (L is the length of the ultrasonic carrier, D is the width of the piezoelectric element, λ is the wavelength of the ultrasonic wave, and θ is outside the nearfield sound field. Negative diffusion angle.)

The present invention is to increase the diameter of the ultrasonic carrier in the direction away from the piezoelectric element so that the ultrasonic wave generated from the piezoelectric element is not reflected on the traveling path to efficiently deliver the ultrasonic wave and uniform sound pressure to prevent damage to the object to be cleaned. In addition, there is an advantage to increase the cleaning efficiency.

In addition, the present invention has the advantage that by designing the length of the ultrasonic carrier to the distance of the interval in which the sound pressure distribution is uniformly uniformized music distribution generated at the end of the ultrasonic carrier to increase the cleaning efficiency for the fine pattern.

Figure 4 is a block diagram showing an ultrasonic cleaning apparatus according to an embodiment of the present invention.

4, the washing | cleaning apparatus of this invention is comprised including the washing | cleaning liquid supply apparatus 2 and the vibrator 4. As shown in FIG.

Here, the cleaning liquid supply device 2 is provided above the object to be cleaned 1 so as to maintain a predetermined gap with the object to be cleaned 1, and supplies the cleaning liquid 3 to the object to be cleaned 1.

The vibrator 4 is provided to face the object to be cleaned 1 to generate ultrasonic waves, and the generated ultrasonic waves are transmitted to the object to be cleaned 1 through the cleaning liquid.

At this time, the vibrator 4 is composed of an ultrasonic carrier 4a and a piezoelectric element 4b provided in the ultrasonic carrier 4a.

Here, the piezoelectric element 4b vibrates by a power source applied from the outside, and the vibrator 4 including the piezoelectric element 4b is integrally mounted to the housing 5, and inside the housing 5. A power supply line 6 for supplying power to the piezoelectric element 4b is provided.

According to a characteristic aspect of the present invention, it is preferable that the ultrasonic wave carrier 4a gradually increase in diameter in the end direction from the coupling portion with the piezoelectric element 4b.

That is, in the conventional ultrasonic carrier 4a, the negative pressure distribution of ultrasonic waves generated from the piezoelectric element is unevenly generated because the diameter thereof decreases or the diameter thereof is constant in the end direction, but the present invention has the diameter of the ultrasonic carrier 4a in the end direction. By increasing the diffusion of the ultrasonic wave is not reflected from the inner wall of the middle of the ultrasonic carrier to improve the uniformity of the sound pressure distribution.

In one embodiment of the present invention, as shown in FIG. 5, the diameter of the ultrasonic carrier is shown as a conical shape that gradually increases toward the end direction, but as shown in FIG. As described above, the outer wall surface may be formed to have a curved shape.

Referring to the shape of the ultrasonic carrier of the ultrasonic cleaning device of the present invention is optimized to increase the cleaning efficiency in detail as follows.

8 and 9 illustrate the basic principle of the vibrator according to the present invention, in which the ultrasonic wave 4a bonded to the piezoelectric element 4b includes ultrasonic waves generated from the piezoelectric element 4b and a near field. Proceed in the form of Far Field.

Here, the near field is generated in the piezoelectric element 4b and 1N or less, which is a near sound field, and has straightness as shown in the drawing.

The far field is generated in the piezoelectric element 4b and the far sound field of 1N or more, and means a section in which the near field ends and the ultrasonic waves are diffused at a predetermined angle.

Comparing the sound pressure distribution of the near field and the far field is shown in Table 1 below.

TABLE 1

division Sound pressure / average sound pressure (%) Standard Deviation / Average Sound Pressure (%) Remarks Near field 0.6 N 463 66 ○ 0.7 N 479 68 ○ 0.8 N 500 70 ○ 0.9 N 792 87 X 1.0 N 925 96 X Farfield
(Far field) 1.2 N 999 98 X 1.5 N 714 84 X 2.0 N 498 70 ○ 3.0 N 464 66 ○ 4.0 N 435 63 ○

Referring to Table 1, the length of the ultrasonic carrier is equal to or more than 0.8N, which is a predetermined distance from the piezoelectric element in the near field, and 2N or less, which is less than or equal to the predetermined distance from the piezoelectric element in the far field. In the case of, the sound pressure distribution is uneven because the ratio of the maximum sound pressure to the average sound pressure is 500% or more and the ratio of the standard deviation to the average sound pressure is 70% or more.

In addition, when the length of the ultrasonic carrier is 0.8N or less and 2N or more, the ratio of the maximum sound pressure to the average sound pressure is 500% or less and the ratio of the standard deviation to the average sound pressure is 70% or less, so that the sound pressure distribution is uniform.

10 and 11 are diagrams illustrating sound pressure distributions generated in an ultra-vibrator.

Referring to FIG. 10, it can be seen that the sound pressure distribution is uniform, with a maximum sound pressure of 319.3% and a standard deviation of 59.1% of the average sound pressure.

In addition, referring to FIG. 11, it can be seen that the sound pressure distribution is non-uniform as the maximum sound pressure for the average sound pressure is 969% and the standard deviation for the average sound pressure is 91.3%.

If the sound pressure distribution is uneven in this way, it is difficult to efficiently clean the fine pattern. Therefore, the length L of the ultrasonic carrier 4a becomes the length of a section in which a near field of 0.1N to 0.8N is formed, or a wave of 2N to 100N. It is preferable to be the length of the section in which the field is formed. Here, N is the distance between the end of the near field of the ultrasonic wave generated from the piezoelectric element and the far field starts, where N = D ² -λ ² / 4λ, D is the width of the piezoelectric element, λ is the wavelength of the ultrasonic wave Means.

In addition, it is preferable that the width W = 2 · (tanθ · L) of the end portion of the ultrasonic wave carrier 4a. Here, θ = 1.2λ / D, D denotes the width of the piezoelectric element, and θ denotes the diffusion angle of sound outside the nearfield sound field.

As described above, the present invention can obtain a uniform sound pressure distribution by increasing the diameter of the ultrasonic carrier in an end direction away from the piezoelectric element to prevent the ultrasonic waves from diffusing and reflecting.

In addition, by optimizing the length of the ultrasonic carrier to a condition in which the negative pressure distribution is uniform, it is possible to prevent damage to the fine pattern and maximize cleaning efficiency.

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 cross-sectional view of the ultrasonic vibrator of the ultrasonic cleaning apparatus according to the prior art.

Figure 4 is a block diagram of the ultrasonic cleaning apparatus according to the present invention.

5 to 7 is a cross-sectional view showing the shape of the various ultrasonic carriers in the ultrasonic cleaning apparatus according to the present invention.

8 and 9 show the basic principle of the vibrator according to the present invention.

10 and 11 is a sound pressure distribution chart measuring the sound pressure generated in the vibrator

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

1: object to be cleaned

2: cleaning liquid supply device

3: cleaning liquid

4: vibrator

    4a: ultrasonic wave carrier, 4b: piezoelectric element

5: housing

6: power line

Claims (4)

A cleaning liquid supply device (2) for supplying a cleaning liquid to the object to be cleaned (1), In the ultrasonic cleaning device comprising an ultrasonic carrier (4a) and a piezoelectric element (4b) provided in the ultrasonic carrier (4a) and is provided so as to face the object to be cleaned 1, the vibrator (4) for generating ultrasonic waves In The ultrasonic carrier 4a gradually increases in diameter in an end direction from a coupling portion with the piezoelectric element 4b, Ultrasonic cleaning device, characterized in that the length (L) of the ultrasonic carrier (4a) is 0.1N ~ 0.8N or 2N ~ 100N. N = D ² -λ ² / 4λ Here, D is the width of the piezoelectric element, λ is the wavelength of the ultrasonic wave, N is the distance between the end of the near field of the ultrasonic wave and the far field begins. The method of claim 1, The ultrasonic carrier (4a) is an ultrasonic cleaning device, characterized in that the conical, multi-stage, or the outer wall surface is of a curved shape. delete The method of claim 1, Ultrasonic cleaning apparatus, characterized in that the width W = 2 · (tanθ · L) of the end of the ultrasonic carrier. θ = 1.2λ / D Where L is the length of the ultrasonic carrier, λ is the wavelength of the ultrasonic wave, D is the width of the piezoelectric element, and θ is the diffusion angle of sound outside the nearfield sound field.

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