JP2024077093A - Cleaning device - Google Patents

Abstract

To perform ultrasonic cleaning properly and efficiently even on a small wafer.SOLUTION: A cleaning device for cleaning a wafer includes an ultrasonic oscillator, an ultrasonic vibrator connected to the ultrasonic oscillator, and a horn connected to the ultrasonic vibrator to transmit ultrasonic vibrations. The horn has a recess on its upper surface to accommodate the wafer, the wafer is accommodated in the recess of the horn, the recess is filled with liquid, the ultrasonic oscillator is operated to cause the ultrasonic vibrator to generate ultrasonic vibrations, and the ultrasonic vibrations are transmitted to the horn to apply the ultrasonic vibrations to the liquid, thereby cleaning the wafer. Preferably, the recess of the horn has a curved surface on its bottom surface, and the bottom surface does not have a flat surface of the size and shape that can accommodate the lower surface of the wafer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cleaning device capable of ultrasonically cleaning small semiconductor wafers.

Device chips mounted on electronic devices are formed, for example, by dividing a disk-shaped semiconductor wafer. A number of planned division lines that intersect with each other are set on the surface of the semiconductor wafer, devices such as ICs are formed in each area defined by the planned division lines, and the semiconductor wafer is divided along the planned division lines, whereby individual device chips can be produced. The semiconductor wafer is cleaned at each stage of processing. An ultrasonic cleaning device is used to clean the semiconductor wafer (see Patent Document 1).

A typical ultrasonic cleaning device consists of a container that holds liquid such as water or an organic solvent, an ultrasonic transducer that applies ultrasonic vibrations to the liquid held in the container, and an ultrasonic generator that supplies high-frequency power to the ultrasonic transducer. A booster that amplifies the ultrasonic vibrations and a horn that acts as a resonator for efficiently transmitting the ultrasonic vibrations are connected to the ultrasonic transducer. The ultrasonic vibrations generated by the ultrasonic transducer are transmitted to the liquid inside the container via the horn.

In recent years, however, there has been progress in the development of a production system known as a minimal fab, which enables small-lot, high-mix production of device chips. In a minimal fab, extremely small wafers, for example about 0.5 inches in size, are processed.

JP 2010-245247 A

When a typical ultrasonic cleaning device is used to ultrasonically clean small, lightweight wafers, the wafers tend to move violently in the liquid in the container, and tend to float to the surface of the liquid. As a result, it is not easy to apply ultrasonic vibrations to the wafer at the specified intensity, and the entire surface of the wafer cannot be cleaned uniformly. One possible solution is to hold the wafer in the liquid in the container with a special jig or the operator's fingers, but in this case, part of the wafer will be covered by the jig, etc., and the entire surface of the wafer cannot be cleaned uniformly.

The present invention was made in consideration of these problems, and aims to provide a cleaning device that can ultrasonically clean wafers appropriately and efficiently.

According to one aspect of the present invention, a cleaning device for cleaning a wafer is provided, the cleaning device comprising an ultrasonic generator, an ultrasonic vibrator connected to the ultrasonic generator, and a horn connected to the ultrasonic vibrator and transmitting ultrasonic vibrations, the horn having a recess on its upper surface for accommodating the wafer, the wafer being accommodated in the recess of the horn, the recess being filled with liquid, the ultrasonic generator being operated to generate ultrasonic vibrations in the ultrasonic vibrator, the ultrasonic vibrations being transmitted to the horn, and the ultrasonic vibrations being applied to the liquid, thereby cleaning the wafer.

Preferably, the recess of the horn has a curved bottom surface, and the bottom surface does not have a flat surface of a size and shape that can accommodate the underside of the wafer.

Also, preferably, the planar shape of the recess is a circle with a diameter of 20 mm or less.

Or, preferably, the planar shape of the recess is a circle with a diameter 1.5 times or less than the diameter of the wafer.

More preferably, the liquid remaining in the recess can be discharged from the recess by applying ultrasonic vibrations to the liquid, thereby atomizing the liquid.

A cleaning device according to one aspect of the present invention includes an ultrasonic generator, an ultrasonic transducer connected to the ultrasonic generator, and a horn connected to the ultrasonic transducer to transmit ultrasonic vibrations. The horn has a recess on its upper surface for accommodating a wafer. When cleaning a wafer with this cleaning device, the wafer is accommodated in the recess of the horn, and the recess is filled with liquid. The ultrasonic generator is then operated to generate ultrasonic vibrations in the ultrasonic transducer, which are then transmitted to the horn and applied to the liquid, thereby cleaning the wafer.

The horn, which is a resonator of ultrasonic vibrations, has limitations on its shape and size in order to function properly, and there are also limitations on the shape and size of the recess formed on the top surface of the horn. As a result, the recess formed in the horn does not provide a space large enough for the wafer contained therein to move around freely. Therefore, the wafer being cleaned does not move around enough to float to the top surface of the liquid. In cleaning performed with the entire surface of the wafer in contact with the liquid, the entire surface of the wafer is cleaned evenly and appropriately.

Moreover, in the cleaning apparatus according to one aspect of the present invention, the wafer is placed in the recess of the horn and cleaned, so there is no need to prepare a container to be connected to the horn as in the past, and there is no need to use liquid in an amount to fill a container with a capacity larger than the recess of the horn. Therefore, the cleaning apparatus according to one aspect of the present invention is inexpensive, compact, and has low operating costs.

Therefore, one aspect of the present invention provides a cleaning device that can ultrasonically clean wafers appropriately and efficiently.

FIG. 1 is a perspective view that illustrates a typical cleaning device capable of ultrasonically cleaning a wafer. FIG. 13 is a cross-sectional view showing a schematic diagram of a recess in a horn for accommodating a wafer. 13 is a cross-sectional view showing a schematic diagram of a recess in a horn according to a modified example for accommodating a wafer. FIG.

An embodiment according to one aspect of the present invention will be described with reference to the attached drawings. First, a wafer to be cleaned by the cleaning apparatus according to this embodiment will be described. FIG. 1 is a perspective view that shows a schematic diagram of a cleaning apparatus 2 according to this embodiment. FIG. 1 includes a perspective view that shows a schematic diagram of a wafer 1.

The wafer 1 is a disk-shaped substrate made of a material such as silicon, and has a front surface 1a and a back surface 1b that are generally parallel to each other. A plurality of planned division lines (not shown) are set on the front surface 1a of the wafer 1, and are arranged in a grid pattern so as to intersect with each other. Devices (not shown), such as ICs (Integrated Circuits) and LSIs (Large Scale Integration), are formed in each of the areas partitioned by the planned division lines on the front surface 1a of the wafer 1.

There are no limitations on the material, structure, etc. of the wafer 1. For example, the wafer 1 may be a substrate made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices, and the wafer 1 does not have to have any devices formed thereon.

Wafer 1 is thinned by grinding from the back surface 1b side, and then divided along the planned division lines to produce multiple thin chips (device chips), each equipped with a device. In the chip manufacturing process, wafer 1 is processed by various processing equipment and cleaned before and after each processing. An ultrasonic cleaning device is used to clean wafer 1.

A typical conventional ultrasonic cleaning device is composed of a container that holds liquid such as water or an organic solvent, an ultrasonic transducer that applies ultrasonic vibrations to the liquid held in the container, and an ultrasonic generator that supplies high-frequency power to the ultrasonic transducer. A booster that amplifies the ultrasonic vibrations and a horn that is a resonator for efficiently transmitting the ultrasonic vibrations are connected to the ultrasonic transducer. The ultrasonic vibrations generated by the ultrasonic transducer are transmitted to the liquid inside the container via the horn.

In recent years, the wafers 1 used have become larger in order to efficiently manufacture a large number of chips from a single wafer 1; for example, wafers 1 with a diameter of 300 mm are used to manufacture chips. However, the various processing devices and facilities for driving the processing devices used to process the large wafers 1 have also become larger, requiring vast premises for chip manufacturing factories. Furthermore, these processing devices and facilities have become very expensive, and operating costs are high.

While wafers 1 are becoming larger, development is also underway on a production system known as a minimal fab, which will enable small-lot, high-mix production of device chips. In a minimal fab, extremely small wafers 1, for example, about 0.5 inches in size, are processed. It is planned that extremely small processing equipment will be installed in a minimal fab, and that facilities such as clean rooms will also be omitted. As a result, in a minimal fab, the equipment will be easier to prepare and operate, and the associated costs will be low.

However, when a small and lightweight wafer 1 is cleaned with a conventional ultrasonic cleaning device, the wafer 1 tends to move in the liquid in the container and tends to float to the surface of the liquid. This tendency is particularly noticeable with extremely small wafers 1 that are the subject of processing in minimal fabs. When the wafer 1 floats to the surface of the liquid, part of the wafer 1 is exposed from the liquid, so ultrasonic vibrations cannot be applied appropriately with a specified intensity to the entire surface of the wafer 1, and the entire surface of the wafer 1 cannot be cleaned uniformly.

The cleaning apparatus 2 according to this embodiment ultrasonically cleans the wafer 1 appropriately and efficiently regardless of the size of the wafer 1. The cleaning apparatus 2 according to this embodiment will be described below. FIG. 1 includes a perspective view that shows a schematic diagram of the cleaning apparatus 2 according to this embodiment. In FIG. 1, some of the configuration is represented by blocks or the like. The cleaning apparatus 2 includes an ultrasonic oscillator (generator) 4 that supplies high-frequency power to an ultrasonic vibrator 10, and an ultrasonic vibrator (converter, transducer) 10 connected to the ultrasonic oscillator 4 via a cable 6.

The ultrasonic oscillator 4 is connected to an AC power source and generates a high-voltage electrical signal at a frequency of about 20 kHz to 300 kHz, which is supplied to the ultrasonic transducer 10. There are no particular restrictions on the ultrasonic oscillator 4 incorporated in the cleaning device 2, and any commercially available ultrasonic oscillator 4 can be used. It is preferable to appropriately select and incorporate an ultrasonic oscillator 4 suitable for the frequency of ultrasonic vibrations that are planned to be generated by the ultrasonic transducer 10 into the cleaning device 2.

The ultrasonic transducer 10 is not particularly limited. The cleaning device 2 can use any ultrasonic transducer 10, such as a Langevin type transducer or a magnetostrictive transducer. The ultrasonic transducer 10 can also be a piezoelectric element.

The cleaning device 2 further includes a horn 12 that is connected to the ultrasonic vibrator 10 and transmits ultrasonic vibrations. The horn 12 resonates with vibrations of a predetermined frequency and vibrates at a predetermined amplitude. The characteristics of the horn 12 are determined by its size, shape, material, etc., and it is designed to resonate at the frequency of the ultrasonic vibrations used in the cleaning device 2. The horn 12 is formed, for example, from aluminum, titanium, stainless steel, or iron.

In the cleaning device 2, the ultrasonic transducer 10 is supported by a support stand 8, and the horn 12 is fixed onto the ultrasonic transducer 10. The tip of the horn 12 is directed upward. In the cleaning device 2, other elements may be disposed between the horn 12 and the ultrasonic transducer 10. For example, the cleaning device 2 may include a booster (not shown) between the horn 12 and the ultrasonic transducer 10. The booster has the function of amplifying the amplitude of the ultrasonic vibration generated by the ultrasonic transducer 10 and transmitting it to the horn 12.

In a typical ultrasonic cleaning device, an ultrasonic vibrator is placed inside a container (cleaning tank) that holds the liquid. Alternatively, the ultrasonic vibrator is fixed to the container via a horn. Alternatively, the tip of the horn to which the ultrasonic vibrator is connected is immersed in the liquid contained in the container. The item to be cleaned is then placed in the liquid contained in the container, and the ultrasonic vibrator is activated to impart ultrasonic vibrations to the liquid.

In contrast, the cleaning apparatus 2 according to this embodiment does not include a container for containing the liquid and the object to be cleaned. In the cleaning apparatus 2 according to this embodiment, the horn 12 has a recess 16 on the upper surface 14 for containing the wafer 1, which is the object to be cleaned, and the liquid. The recess 16 is, for example, a disk-shaped space of a size and shape capable of containing the wafer 1, and this space is exposed on the upper surface 14 of the horn 12. The horn 12 having the recess 16 can be obtained by machining a conventional horn, or the like.

The shape and size of the horn 12 are set so that the horn 12 resonates with the ultrasonic vibrations generated by the ultrasonic transducer 10. Therefore, there is a limit to the size of the top surface 14 of the horn 12, and there is also a limit to the size of the recess 16 formed on the top surface 14. Furthermore, if the recess 16 is too large, the characteristics of the horn 12 will change significantly, so the size of the recess 16 is limited from that perspective as well. Alternatively, the size, etc. of the horn 12 may be determined so that the horn 12 has predetermined characteristics when the recess 16 is formed.

For example, the planar shape of the recess 16 of the horn 12 is a circle with a diameter of 20 mm or less. Preferably, it is a circle with a diameter of 14 mm or less. Since the recess 16 needs to be of a size and shape capable of accommodating the wafer 1, the diameter of the circular recess 16 in the planar shape needs to exceed the diameter of the wafer 1. On the other hand, if the diameter of the recess 16 is too large, the wafer 1 will be able to move around freely inside the recess 16. For this reason, it is preferable that the planar shape of the recess 16 is a circle with a diameter of 1.5 times or less the diameter of the wafer 1.

In order to accommodate the wafer 1 in the recess 16, it is preferable that the depth of the recess 16 exceeds the thickness of the wafer 1. On the other hand, if the recess 16 is too deep, a large amount of liquid will be used and it will be more difficult to move the wafer 1 in and out of the recess 16. Also, the change in the characteristics of the horn 12 caused by the recess 16 will be significant. Therefore, for example, the depth of the recess 16 is preferably 1.5 mm or less, and more preferably 1.0 mm or less. However, the planar shape, size of the planar shape, and depth of the recess 16 are not limited to these.

The cleaning device 2 may be provided with a pipe-shaped supply nozzle 20 above the horn 12 that supplies liquid to the recess 16 of the horn 12. When the cleaning device 2 is provided with the supply nozzle 20, the supply nozzle 20 may be configured to be movable between the top and the outside of the horn 12. For example, it is preferable that the supply nozzle 20 is retracted from above the horn 12 when the wafer 1 is being loaded or unloaded into the recess 16, and the tip of the supply nozzle 20 is positioned above the horn 12 when liquid is supplied from the supply nozzle 20 to the recess 16.

Here, the liquid supplied from the supply nozzle 20 or the like to the recess 16 will be described. FIG. 2 includes a cross-sectional view showing a schematic of the liquid 22 supplied to the recess 16. The liquid 22 is appropriately selected depending on the material of the wafer 1 to be cleaned, the material and amount of contaminants adhering to the wafer 1, the cleanliness required of the wafer 1 after cleaning, etc.

In the cleaning device 2, for example, pure water, pure water with added surfactant, etc., hydrocarbon-based liquid such as hexane, chlorine-containing liquid such as dichloromethane or trichloroethylene, alcohol-based liquid such as isopropyl alcohol, etc. are used as the liquid 22. However, the liquid 22 is not limited to these, and acetone may also be used.

The task of transporting and storing the wafer 1 in the recess 16 of the horn 12 may be performed, for example, manually by an operator. Alternatively, the cleaning device 2 may be equipped with a transport unit that transports the wafer 1, and the wafer 1 may be transported by the transport unit.

Figure 3 shows a side view that shows a schematic of a part of the transport unit 24 equipped in the cleaning device 2. The transport unit 24 is, for example, a suction nozzle or a suction collet that can be raised and lowered. The transport unit 24 can, for example, contact the top surface (surface 1a) of the wafer 1 with its bottom surface and hold the wafer 1 by suction through suction holes that reach the bottom surface.

The wafer 1 can be moved by moving the transport unit 24 while the transport unit 24 is holding the wafer 1 by suction, and the transport of the wafer 1 is completed when the suction hold of the wafer 1 is released after the wafer 1 has been moved to a specified destination.

Next, the cleaning operation of the wafer 1 by the cleaning device 2 will be described. First, the wafer 1 is loaded into the recess 16 of the horn 12. The wafer 1 may be loaded into the recess 16 by, for example, a transport unit 24 (Figure 3). Figure 2 shows a schematic cross-sectional view of the wafer 1 accommodated in the recess 16 of the horn 12.

Before or after placing the wafer 1 in the recess 16 of the horn 12, the tip of the supply nozzle 20 is positioned above the horn 12, and liquid 22 is supplied from the supply nozzle 20 to the recess 16, filling the recess 16 with the liquid 22. At this time, it is preferable that the liquid 22 that overflows from the recess 16 remains on the top surface 14 of the horn 12 due to surface tension. It is also preferable that a sufficient area is secured on the top surface 14 of the horn 12 so that sufficient liquid 22 remains around the recess 16 due to surface tension.

For example, it is preferable that the diameter of the planar shape of the circular recess 16 is 75% or less of the diameter of the top surface 14 of the horn 12. Alternatively, it is preferable that the width (distance between the inner peripheral edge and the outer peripheral edge) of the annular top surface 14 surrounding the recess 16 is 5 mm or more. However, the size of the top surface 14 is not limited to this.

Then, the ultrasonic oscillator 4 is operated to generate ultrasonic vibrations in the ultrasonic vibrator 10, which are then transmitted to the horn 12 and applied to the liquid 22. The wafer 1 is then ultrasonically cleaned inside the recess 16 of the horn 12.

When the wafer 1 is ultrasonically cleaned, the wafer 1 floats in the liquid 22. However, in the cleaning device 2 according to this embodiment, the wafer 1 is housed in the recess 16 formed in the top surface 14 of the horn 12 and cleaned, so the wafer 1 is less likely to move around compared to conventional ultrasonic cleaning devices. This is because there is no space large enough inside the recess 16 formed in the top surface 14 of the horn 12 for the wafer 1 to move around freely.

Therefore, in the cleaning apparatus 2 according to this embodiment, there is no need to hold down the wafer 1 with the operator's hands or a dedicated holding tool, etc., and the entire surface of the wafer 1 is exposed and not hidden by the operator's fingers, etc. In the cleaning apparatus 2, the wafer 1 during cleaning is unlikely to float up to the surface of the liquid 22, and the entire surface of the wafer 1 is cleaned uniformly and appropriately.

After cleaning of the wafer 1 is completed, the wafer 1 is removed from the recess 16 of the horn 12. The wafer 1 is removed, for example, by the transport unit 24 (see FIG. 3). If the transport unit 24 is an adsorption collet or the like, the lower end of the transport unit 24 is brought into contact with the upper surface (surface 1a) of the wafer 1, the transport unit 24 is caused to suck and hold the wafer 1, and the transport unit 24 is moved. This causes the cleaned wafer 1 to be removed from the recess 16.

Here, because the recess 16 of the horn 12 has a small diameter, even if the wafer 1 moves inside the recess 16 during ultrasonic cleaning, a part of the wafer 1 always overlaps with the center of the bottom surface 18 of the recess 16. Therefore, if the suction collet is lowered toward the center of the bottom surface 18 of the recess 16, the bottom end of the suction collet comes into contact with the wafer 1. In other words, the cleaning device 2 does not require a sensor or the like to identify the position of the wafer 1 being carried out by the transport unit 24.

The liquid 22 may be drained from the recess 16 before or after the wafer 1 is removed from the recess 16. The liquid 22 may be drained from the recess 16, for example, by suction. The cleaning device 2 may be equipped with a suction unit (not shown) configured in the same manner as the transport unit 24, and the liquid 22 may be sucked out of the recess 16 by the suction unit. The transport unit 24 may also function as the suction unit. Since only a small amount of the liquid 22 accumulates in the recess 16, it is easy to suck out the liquid 22.

Alternatively, in the cleaning device 2 according to this embodiment, the liquid 22 remaining in the recess 16 may be subjected to ultrasonic vibrations to atomize (vaporize) the liquid 22, thereby discharging the liquid 22 from the recess 16. That is, ultrasonic vibrations are generated in the ultrasonic transducer 10, and the ultrasonic vibrations are propagated from the horn 12 to the liquid 22, thereby applying ultrasonic vibrations to the liquid 22 and atomizing the liquid 22. Again, because only a small amount of the liquid 22 accumulates in the recess 16, removal of the liquid 22 by atomization is easy.

In this way, in the cleaning apparatus 2 according to this embodiment, it is easy to remove the liquid 22 stored in the recess 16 of the horn 12 each time a wafer 1 is cleaned, and to fill the recess 16 with new liquid 22. Therefore, in the cleaning apparatus 2 according to this embodiment, multiple wafers 1 can be cleaned one after another in clean liquid 22.

If the bottom surface 18 of the recess 16 of the horn 12 has a flat surface and the flat surface is of a size and shape that can accommodate the underside (rear surface 1b) of the wafer 1, the bottom surface 18 and the underside of the wafer 1 tend to stick to each other. In this case, when liquid 22 is supplied to the recess 16 and the wafer 1 is ultrasonically cleaned, the liquid 22 does not easily penetrate between the underside (rear surface 1b) of the wafer 1 and the bottom surface 18, so the underside of the wafer 1 is not properly cleaned. Furthermore, because the wafer 1 is difficult to peel off from the bottom surface 18, it becomes difficult to remove the wafer 1 from the recess 16 after cleaning is completed.

Therefore, it is preferable that the recess 16 of the horn 12 has a curved surface on the bottom surface 18 as shown in FIG. 2. For example, the outer periphery of the bottom surface 18 is lower than the center. Furthermore, it is preferable that the bottom surface 18 of this recess 16 does not have a flat surface of a size and shape that can accommodate the underside (rear surface 1b) of the wafer 1 contained in the recess 16. In this case, at least a part of the underside of the wafer 1 does not contact the bottom surface 18 of the recess 16, and a gap is created between a part of the underside of the wafer 1 and the bottom surface 18.

If a gap exists between at least a portion of the underside of the wafer 1 and the bottom surface 18 of the recess 16, the liquid 22 will also enter this gap when the recess 16 is filled with the liquid 22. In this case, when the ultrasonic vibrator 10 is operated and ultrasonic vibrations are transmitted to the horn 12, the liquid 22 will enter the entire area between the underside of the wafer 1 and the bottom surface 18 of the recess 16 from this gap, causing the wafer 1 to float in the liquid 22. Therefore, the underside of the wafer 1 is also properly cleaned.

In this case, the adhesion of the wafer 1 to the bottom surface 18 is weaker than when the entire lower surface of the wafer 1 is in contact with the bottom surface 18 of the recess 16. Therefore, when the wafer 1 is removed from the recess 16 after cleaning of the wafer 1 is completed, the wafer 1 can be peeled off from the bottom surface 18 relatively easily.

As described above, the cleaning apparatus 2 according to this embodiment cleans the wafer 1 inside the recess 16 formed in the horn 12. Therefore, the wafer 1 being cleaned does not move around enough to float to the top surface of the liquid 22. In cleaning performed with the entire surface of the wafer 1 in contact with the liquid 22, the entire surface of the wafer 1 is cleaned uniformly and appropriately. Moreover, the cleaning apparatus 2 does not require a container for storing the liquid 22 other than the horn 12, and only a very small amount of the liquid 22 is used. Therefore, it is inexpensive, small, and has low operating costs.

In the above embodiment, the bottom surface 18 of the recess 16 of the horn 12 has a curved surface, and the outer periphery of the bottom surface 18 is lower than the center, as shown in FIG. 2. However, one aspect of the present invention is not limited to this.

Figure 3 is a cross-sectional view showing a schematic diagram of a cleaning device 2a according to a modified example. In this cleaning device 2a, the shape of the bottom surface 18 of the recess 16a formed in the upper surface 14a of the horn 12a is different from the bottom surface 18a of the recess 16 described in Figure 2. In the cleaning device 2 shown in Figure 3, the outer periphery of the bottom surface 18a of the recess 16a is higher than the center.

In this case, as shown in FIG. 3, the wafer 1 accommodated in the recess 16a is supported by the outer periphery of the bottom surface 18a of the recess 16a, so most of the bottom surface (back surface 1b) of the wafer 1 does not contact the bottom surface 18a of the recess 16a. Therefore, the bottom surface (back surface 1b) of the wafer 1 does not stick to the bottom surface 18a of the recess 16a, and the liquid 22 is likely to come into contact with the entire surface of the wafer 1 when the wafer 1 is ultrasonically cleaned. In addition, the wafer 1 can be easily removed from the recess 16a.

In addition, the structures, methods, etc. according to the above embodiments can be modified as appropriate without departing from the scope of the present invention.

REFERENCE SIGNS LIST 1 wafer 1a front surface 1b back surface 2, 2a cleaning device 4 ultrasonic oscillator 6 cable 8 support 10 ultrasonic transducer 12, 12a horn 14, 14a top surface 16, 16a recess 18, 18a bottom surface 20 supply nozzle 22 liquid 24 transfer unit

Claims (5)

A cleaning apparatus for cleaning a wafer, comprising:
An ultrasonic oscillator;
an ultrasonic transducer connected to the ultrasonic oscillator;
a horn connected to the ultrasonic transducer and transmitting ultrasonic vibrations;
The horn has a recess on an upper surface for receiving the wafer;
A cleaning apparatus comprising: placing the wafer in the recess of the horn; filling the recess with liquid; operating the ultrasonic oscillator to generate ultrasonic vibrations in the ultrasonic vibrator; and transmitting the ultrasonic vibrations to the horn and applying the ultrasonic vibrations to the liquid, thereby cleaning the wafer. The recess of the horn has a curved surface at its bottom,
2. The cleaning apparatus according to claim 1, wherein the bottom surface does not have a flat surface of a size and shape that can accommodate the lower surface of the wafer. The cleaning device according to claim 1 or 2, characterized in that the planar shape of the recess is a circle with a diameter of 20 mm or less. The cleaning device according to claim 1 or 2, characterized in that the planar shape of the recess is a circle with a diameter 1.5 times or less than the diameter of the wafer. The cleaning device according to claim 1 or 2, characterized in that the liquid remaining in the recess can be discharged from the recess by applying ultrasonic vibrations to the liquid, thereby atomizing the liquid.

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