JP2009094140A - Piezoelectric vibrator, its manufacturing method, and ultrasonic cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator propagating vibrations in a requested direction although the vibrator is tablet-shaped, to provide its manufacturing method, and also provide an ultrasonic cleaning apparatus increasing the cleaning performance independently of the design of the apparatus, by using the piezoelectric vibrator. <P>SOLUTION: The ultrasonic cleaning apparatus 10 comprises a substrate holding means 11 to hold a substrate W, a cleaning means 12 to propagate vibration from the piezoelectric vibrator 15 in a cleaning liquid 14 to ultrasonically clean the substrate W; and an ultrasonic oscillator 13 to apply a high-frequency voltage to the piezoelectric vibrator 15. The piezoelectric vibrator 15 is a tablet-shaped piezoelectric vibrator having vibrating electrodes 16a and 16b and its polarization axes P are tilted at preset angles relative to its thickness direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention supplies semiconductor wafers, photomask glass substrates, liquid crystal display glass substrates, optical disk substrates (hereinafter simply referred to as “substrates”) and the like by supplying a cleaning liquid with ultrasonic vibrations for cleaning. The present invention relates to an ultrasonic cleaning apparatus that performs processing, and further relates to a piezoelectric vibrator used in an ultrasonic cleaning apparatus or the like and a manufacturing method thereof.

In the manufacturing process of semiconductors and the like, when a process step is performed on a substrate used for semiconductor manufacturing such as a semiconductor wafer or a photomask substrate, if particles such as organic matter, metal dust, or foreign matter are attached to the substrate, the substrate In-plane uniform processing is not performed, and such substrates are indirectly cross-contaminated from other substrates, leading to a decrease in product manufacturing yield. Therefore, before processing a normal substrate, particles and the like are removed from the substrate by cleaning the substrate with a cleaning device.
Conventional cleaning apparatuses for cleaning such substrates include a batch type cleaning apparatus capable of simultaneously cleaning a plurality of substrates and a single wafer cleaning apparatus for cleaning substrates one by one.

In the batch type ultrasonic cleaning apparatus, the tank type is the mainstream. For example, a substrate is immersed in a tank (cleaning tank) containing a cleaning liquid, and a high frequency voltage is applied from a piezoelectric vibrator provided at the bottom of the tank. Thus, ultrasonic cleaning is performed by applying ultrasonic waves to the cleaning liquid.
When a high frequency voltage is applied to the piezoelectric vibrator, ultrasonic vibration with a specific frequency is generated. By propagating this ultrasonic vibration to the cleaning liquid in the cleaning tank, cavitation occurs in the cleaning liquid, and the substrate in the cleaning liquid can be cleaned by this cavitation. The ultrasonic cleaning action includes cavitation, particle acceleration, straight flow, and chemical action cleaning action.

  In addition, the single-wafer type ultrasonic cleaning apparatus is mainly a flowing water type. For example, a piezoelectric vibrator is attached to a nozzle, and ultrasonic vibration is propagated to the cleaning liquid supplied into the nozzle, and then the cleaning liquid is used as a substrate. Ultrasonic cleaning can be performed by spraying toward (object to be cleaned).

A nozzle-type substrate cleaning method and apparatus in which ultrasonic vibration is applied to the cleaning liquid in this way are also disclosed in, for example, Patent Document 1. In Patent Document 1, a piezoelectric vibrator as shown in FIG. 5 is used for the purpose of improving the cleaning power by an ultrasonic nozzle.
FIG. 5 is a schematic view of a conventional focusing type piezoelectric vibrator.
In particular, in FIG. 5A, the piezoelectric body 51a itself is formed in the shape of a concave sphere, and vibration is propagated because the polarization axis 5P is not inclined with respect to the thickness direction of the piezoelectric body, that is, is parallel. This is a concave spherical vibrator 50a in which ultrasonic vibrations are focused at a desired focal point 5F in the medium to be caused.
FIG. 5B shows that the piezoelectric body 51b itself has a flat plate shape and the polarization axis 5P is not inclined with respect to the thickness direction of the piezoelectric body, that is, is parallel, and a half-wave plate 55 is provided on the piezoelectric body 51b. By combining the plano-concave lens 56 through the lens-coupled focusing vibrator 50b, the ultrasonic vibration is focused at a desired focal point 5F in the medium in which the vibration is propagated.

By using a piezoelectric vibrator having a curved surface in this way for an ultrasonic nozzle, the ultrasonic vibration is focused on the surface to be cleaned like a lens to increase the amplitude.
However, in the method of intentionally manipulating the direction of sound waves with this vibrator shape, the shape of the piezoelectric vibrator is limited, so the degree of freedom in designing the device using the piezoelectric vibrator is reduced and the radiation plate is used. When connecting a plurality of piezoelectric vibrators, there is a problem in that joining of the vibrators to the radiation plate is difficult.

On the other hand, if a piezoelectric vibrator having a conventional flat plate shape and a polarization axis parallel to the thickness direction is used in the cleaning device, its cleaning capability is limited.
A conventional piezoelectric vibrator having a flat plate shape and a polarization axis parallel to the thickness direction has a property that the sound wave is focused or diffused depending on the resonance frequency and the shape of the piezoelectric vibrator. Therefore, for example, by using a piezoelectric vibrator having such a curved surface for an ultrasonic nozzle at a frequency at which it is difficult to focus the sound wave due to the characteristics of the piezoelectric vibrator, It has been possible to focus on the surface to be cleaned.
Also, even in a piezoelectric vibrator that is easy to focus at the resonance frequency and its shape, by using a piezoelectric vibrator having a curved surface, the sound wave is focused like a lens, and the amplitude is increased compared to a conventional flat plate-shaped piezoelectric vibrator. Things have been done.

  However, in the piezoelectric vibrator having this curved surface, it is difficult to process the radiation plate joined thereto. Although a plating process for the radiation surface is also conceivable, it is not preferable because the plating is peeled off by the ultrasonic vibration of the piezoelectric vibrator. If it is a metal foil of 0.1 mm or less (tantalum, platinum, stainless steel, etc.), by pressing the metal foil in accordance with the curved surface of the piezoelectric vibrator, it is possible to forcibly conform to the vibrator shape and join. Is possible. However, this is limited to the metal foil. When the radiation plate is thick, it is difficult to match the shapes of the piezoelectric vibrator and the radiation plate, thereby making joining difficult. In addition, when the ultrasonic cleaning device is used in a process that dislikes metal ions, a quartz radiation plate or the like is bonded to the piezoelectric vibrator. In a piezoelectric vibrator having this curved surface, quartz radiation is used. It is difficult to join the plates, and it is difficult to use them in the above process.

JP 2000-216126 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a piezoelectric vibrator capable of propagating vibration in a desired direction while the shape of the piezoelectric vibrator is a flat plate shape. An object of the present invention is to provide an ultrasonic cleaning apparatus that provides the manufacturing method and further uses the piezoelectric vibrator so that the device design is not limited to the piezoelectric vibrator and the cleaning performance can be further improved.

In order to achieve the above object, the present invention at least cleans the substrate held by the substrate to be cleaned and ultrasonically cleaning the substrate held by the substrate holding means by propagating the vibration of the piezoelectric vibrator to the cleaning liquid. In an ultrasonic cleaning apparatus having a cleaning means and an ultrasonic oscillator that applies a high frequency voltage to the piezoelectric vibrator of the cleaning means,
The piezoelectric vibrator is a plate-shaped piezoelectric vibrator in which a vibrating electrode is formed,
The flat plate-shaped piezoelectric vibrator is provided with an ultrasonic cleaning device characterized in that its polarization axis is inclined at a desired angle with respect to the thickness direction (Claim 1).

  As described above, the ultrasonic cleaning apparatus according to the present invention is such that the piezoelectric vibrator to be used has a flat plate shape on which the vibrating electrode is formed, but its polarization axis is inclined at a desired angle with respect to the thickness direction. . Thereby, since the piezoelectric vibrator to be used has a flat plate shape, the attachment to the cleaning means is not restricted, and the polarization axis is at a desired angle with respect to the thickness direction, so that the vibration is vibrated in the desired direction in the cleaning liquid. By propagating, the substrate can be cleaned without waste in a desired range, and the cleaning ability can be improved.

In this case, the piezoelectric vibrator may be a converging flat plate vibrator in which the inclination of the polarization axis with respect to the thickness direction is controlled so that the vibration propagated to the cleaning liquid is converged to a desired point or line ( Claim 2).
In this way, the flat plate-shaped piezoelectric vibrator to be used has a focusing flat plate vibration in which the inclination of the polarization axis with respect to the thickness direction is controlled so that the vibration propagated to the cleaning liquid is focused on a desired point or line in the cleaning liquid. If it is a child, the vibration propagated to the cleaning liquid is focused on the surface to be cleaned of the substrate, and it is possible to obtain a larger amplitude than that of a conventional flat-plate-shaped vibrator, thereby improving the cleaning ability.

Further, the piezoelectric vibrator can be a diffusion type flat plate vibrator in which the inclination of the polarization axis with respect to the thickness direction is controlled so that the vibration propagated to the cleaning liquid is diffused.
As described above, if the flat plate-shaped piezoelectric vibrator to be used is a diffusion type flat plate vibrator in which the inclination of the polarization axis with respect to the thickness direction is controlled so that the vibration propagated to the cleaning liquid is diffused in the cleaning liquid, the cleaning liquid The vibration propagated to the surface diffuses, and a wider area than the size of the piezoelectric vibrator can be cleaned, and cleaning unevenness can be reduced.

The cleaning unit may include a nozzle that houses the piezoelectric vibrator, and the nozzle may discharge a cleaning liquid toward the substrate.
In this way, by using the piezoelectric vibrator in a so-called nozzle type ultrasonic cleaning apparatus, vibration can be applied along the shape of the nozzle that discharges the cleaning liquid, and the vibration collides with the inner wall of the nozzle and cancels out. Can be suppressed. Thereby, a desired range can be washed intensively without weakening the vibration intensity due to the shape of the nozzle.

Further, the cleaning means may include a cleaning tank for storing the cleaning liquid, and the piezoelectric vibrator may be attached to the outer wall of the cleaning tank via a radiation plate.
Thus, by using the piezoelectric vibrator in a so-called tank-type ultrasonic cleaning apparatus, for example, if a diffusion type flat plate vibrator is used as the piezoelectric vibrator, the shape of the vibrator is a flat plate shape. It is easy to attach the individual vibrators to the radiation plate, and furthermore, since ultrasonic vibration is diffused, it is possible to clean a wider area than the size of the piezoelectric vibrator.

Further, the present invention is a plate-shaped piezoelectric vibrator having vibration electrodes on the front and back surfaces of a plate-shaped piezoelectric body, and vibrating by applying a high frequency voltage to the vibration electrode,
A piezoelectric vibration characterized in that a polarization axis of the piezoelectric vibrator is inclined with respect to a thickness direction of the piezoelectric body so as to be focused or diffused on a desired point or line in a medium through which the vibration propagates. A child is provided (claim 6).

  Thus, if the polarization axis of the piezoelectric vibrator is tilted with respect to the thickness direction of the piezoelectric body so as to be focused or diffused on a desired point or line in the medium through which the vibration propagates, the piezoelectric vibrator Since the vibration propagates in a desired direction while maintaining the shape of the plate in a flat plate shape, when designing a device in which the cleaning ability can be utilized to the maximum and the vibration propagation direction is controlled, The shape can be designed in the same manner as a conventional flat plate shape without being limited to the shape, and the degree of freedom can be maintained. Since the shape of the piezoelectric vibrator is the same as the conventional flat plate shape, the radiation plate joined thereto can be easily processed and joined. When the ultrasonic cleaning device is used in a process that dislikes metal ions, a quartz radiation plate or the like is joined to the piezoelectric vibrator, and this quartz radiation plate can also be easily joined.

Furthermore, the present invention includes at least a preparation step of preparing a plate-shaped piezoelectric body,
A temporary electrode step of forming temporary electrodes for polarization on the front and back surfaces of the piezoelectric body;
A polarization step of applying a DC strong electric field to the temporary electrode to polarize the piezoelectric body;
Removing the temporary electrode from the front and back surfaces of the piezoelectric body;
A method of manufacturing a plate-shaped piezoelectric vibrator including a vibrating electrode step of forming a vibrating electrode on the front and back surfaces of the piezoelectric body,
During the temporary electrode step, a temporary electrode having a pattern is formed on the front and back surfaces of the piezoelectric body so that the polarization axis of the piezoelectric vibrator is inclined at a desired angle with respect to the thickness direction.
During the polarization step, a DC strong electric field is individually applied to the temporary electrodes formed on the front and back surfaces of the piezoelectric body one by one or two sets,
In the vibration electrode step after the removing step, a vibration electrode is formed on the entire front surface and back surface of the piezoelectric body.

  Thus, during the temporary electrode process, the temporary electrodes having a pattern are formed on the front and back surfaces of the piezoelectric body so that the polarization axis of the piezoelectric vibrator is inclined at a desired angle with respect to the thickness direction. At this time, a DC strong electric field is individually applied to the temporary electrodes formed on the front and back surfaces of the piezoelectric body one by one or two sets, and the vibrating electrodes are formed on the entire front and back surfaces of the piezoelectric body during the vibrating electrode process. Thus, it is possible to easily manufacture a piezoelectric vibrator in which the polarization axis of the piezoelectric vibrator is inclined by a desired angle with respect to the thickness direction of the piezoelectric body.

In this case, a pattern in which the polarization axis is inclined with respect to the thickness direction of the piezoelectric body so that the pattern of the temporary electrode is focused or diffused to a desired point or line in the medium through which vibration by the piezoelectric vibrator propagates. (Claim 8).
As described above, the pattern of the temporary electrode is a pattern in which the polarization axis is inclined with respect to the thickness direction of the piezoelectric body so as to be focused or diffused to a desired point or line in the medium where the vibration caused by the piezoelectric vibrator propagates. Thus, a piezoelectric vibrator in which the polarization axis of the piezoelectric vibrator is inclined with respect to the thickness direction of the piezoelectric body so that the polarization axis of the piezoelectric vibrator is focused or diffused on a desired point or line in the medium through which the vibration propagates can be manufactured. .

In the vibrating electrode step, the vibrating electrode is preferably formed by electroless plating.
Thus, if the vibrating electrode is formed by electroless plating, the vibrating electrode can be formed on the entire surface while maintaining the polarization state of the already polarized piezoelectric body.

In the ultrasonic cleaning apparatus of the present invention, the attachment of the piezoelectric vibrator to be used to the cleaning means is not limited, and the polarization axis is at a desired angle with respect to the thickness direction. By propagating vibration, the substrate can be cleaned without waste in a desired range, and the cleaning ability can be improved.
In addition, the piezoelectric vibrator of the present invention can be designed in the same manner as a conventional flat plate shape without being limited by the shape of the vibrator when designing a device in which the vibration propagation direction is controlled. Freedom can be maintained.
Furthermore, according to the method for manufacturing a piezoelectric vibrator of the present invention, it is possible to easily manufacture a piezoelectric vibrator having a polarization axis inclined by a desired angle with respect to the thickness direction.

As described above, in a conventional ultrasonic cleaning apparatus of the nozzle type, the shape of the vibrator is normally flat for the purpose of positively focusing the ultrasonic vibration propagating from the piezoelectric vibrator to the cleaning liquid and increasing the amplitude. It has been made to have a curved surface from the state. For example, in a disk type piezoelectric vibrator, the shape of the piezoelectric body is used as a concave surface such as a lens to focus the sound wave on the focal point. In the case of a rectangular piezoelectric body, the surface has a plano-concave shape. By combining the lens, the effect of focusing the sound wave was obtained as described above.
However, in this method of manipulating the direction of a sound wave that intentionally propagates depending on the shape of the piezoelectric vibrator, the design of the apparatus is restricted, and it is difficult to join the piezoelectric vibrator to the radiation plate.

  In order to solve such problems, the present inventors have conducted extensive research. If the piezoelectric vibrator has a generally flat plate shape (a flat plate may be used, the surface may be a circle or a polygon) and the ultrasonic vibration can be propagated in the cleaning liquid so that it converges, a normal flat plate It has been conceived that an ultrasonic cleaning device with higher cleaning power can be obtained without depriving the degree of freedom of device design using a piezoelectric vibrator, but there has been no method for manufacturing such a piezoelectric vibrator.

Therefore, the present inventors have further studied, and in the polarization process of the piezoelectric vibrator, the polarization performed in parallel with the thickness direction of the piezoelectric body is inclined toward the center so that the propagating vibration is converged. The direction of the sound wave could be diffused by focusing the direction of the sound wave or tilting it outward so that the propagating vibration would diffuse. As a result, it is possible to manipulate the directionality of the sound wave without changing the shape of the piezoelectric vibrator itself (in the form of a flat plate), and it can be handled in the same manner as a conventional vibrator. I was able to complete it.
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereto.

First, a nozzle type ultrasonic cleaning apparatus will be described as a first embodiment of the ultrasonic cleaning apparatus according to the present invention.
FIG. 1 is a schematic view showing a first embodiment of an ultrasonic cleaning apparatus according to the present invention.
FIG. 3 is a schematic view showing a focusing plate oscillator according to the present invention.
FIG. 4 is a schematic view showing a diffusion type flat plate vibrator according to the present invention.

The nozzle-type ultrasonic cleaning apparatus 10 includes a substrate holding unit 11 that holds a substrate W of an object to be cleaned, and a substrate W held by the substrate holding unit. A cleaning unit 12 for sonic cleaning and an ultrasonic oscillator 13 for applying a high frequency voltage to the piezoelectric vibrator of the cleaning unit are provided.
The piezoelectric vibrator 15 is a plate-shaped piezoelectric vibrator in which the vibration electrodes 16a and 16b are formed. The polarization axis P of the piezoelectric vibrator 15 is inclined at a desired angle with respect to the thickness direction T.

  Thus, in the nozzle type ultrasonic cleaning apparatus 10 of the present invention, the piezoelectric vibrator 15 to be used has a flat plate shape, but its polarization axis is inclined at a desired angle with respect to the thickness direction. Since the attachment to the cleaning means 12 is not limited by the shape, and the polarization axis P is at a desired angle with respect to the thickness direction T, the vibration is propagated in the desired direction in the cleaning liquid 14 so that the substrate is Cleaning can be performed without waste in the range, and the cleaning ability can be improved.

Further, as shown in FIG. 3, the piezoelectric vibrator 15 is a converging flat plate vibration in which the inclination of the polarization axis P with respect to the thickness direction T is controlled so that the vibration propagated to the cleaning liquid 14 is converged to a desired point F or line. Preferably, a child 35 is used.
In this way, the flat plate-shaped piezoelectric vibrator to be used has a focusing flat plate vibration in which the inclination of the polarization axis with respect to the thickness direction is controlled so that the vibration propagated to the cleaning liquid is focused on a desired point or line in the cleaning liquid. If it is a child, the vibration propagated to the cleaning liquid is focused on the surface to be cleaned of the substrate, and it is possible to obtain a larger amplitude than that of a conventional flat-plate-shaped vibrator, thereby improving the cleaning ability.

Further, in the first embodiment, since the nozzle type ultrasonic cleaning apparatus 10 is used, the substrate holding means 11 can hold the substrate W horizontally at three points and rotate the substrate as shown in FIG. Is also possible. Since such an apparatus processes substrates one by one, it is sometimes called a single wafer cleaning apparatus.
The cleaning unit 12 is a nozzle 12 that houses the piezoelectric vibrator 15, and the nozzle 12 discharges the cleaning liquid 14 toward the substrate W.
In this way, by using a piezoelectric vibrator with a tilted polarization axis in a so-called nozzle type ultrasonic cleaning device, vibration can be applied along the shape of the nozzle that discharges the cleaning liquid, and vibration is applied to the inner wall of the nozzle. It is possible to suppress the collision and cancellation. Thereby, a desired range can be washed intensively without weakening the vibration intensity due to the shape of the nozzle.

Here, as a matter of course, the ultrasonic cleaning apparatus is not limited to the case of using a conical nozzle as shown in FIG.
When the nozzle has a conical shape as shown in FIG. 1 and has a single cleaning liquid discharge port and is circular, the plate-shaped piezoelectric vibrator to be used has its polarization axis P completely aligned with the converging shape of the inner wall of the nozzle. It is preferable to focus on one point F. Further, this point F is preferably focused on the cleaning surface of the substrate.
In this way, in the case of the converging flat plate vibrator 35 in which the polarization axis P is focused at the desired point F, a plate-shaped piezoelectric vibrator (normal vibrations) whose polarization axes P are all parallel to the thickness direction T. As compared with the child), the high-frequency voltage applied from the ultrasonic oscillator 13 allows the vibrator 35 to propagate the ultrasonic vibration along the polarization axis P to the cleaning liquid 14, and the amplitude is attenuated by the wave reflected on the inner wall. In addition, it is possible to propagate the ultrasonic vibration having the maximum amplitude on the cleaning surface.

  When there is one discharge port of the nozzle as a cleaning means and the shape of the nozzle is a slit shape (not shown), the polarization of the flat plate-shaped piezoelectric vibrator to be used is aligned with the converging shape of the inner wall of the nozzle. It is preferred that the axis P is focused on a line, and again this focused line is better focused on the cleaning surface of the substrate for the purpose of increasing the amplitude similar to the case where it is focused on the point.

On the other hand, if the nozzle is formed so that the cleaning liquid diffuses outward (not shown) regardless of whether the nozzle outlet is circular or slit-shaped, it propagates to the cleaning liquid 14 as shown in FIG. It is preferable to use a diffusion-type flat plate vibrator 45 in which the inclination of the polarization axis P with respect to the thickness direction T is controlled so that the generated vibration is diffused.
As described above, the vibration propagates to the cleaning liquid along the inner wall of the nozzle, so that the amplitude is less attenuated by the wave reflected on the inner wall, and the vibration propagated to the cleaning liquid diffuses and is larger than the size of the piezoelectric vibrator. A wide area can be cleaned.

  Therefore, by using a plate-shaped piezoelectric vibrator in which the propagation direction of the ultrasonic vibration is appropriately controlled so that the ultrasonic vibration propagates along the inner wall of the nozzle (the polarization axis is inclined at a desired angle). Various cleaning effects can be exhibited.

  The shape of the piezoelectric vibrator to be used is limited to a flat plate shape from the viewpoint of device design, but the shape seen from the plane is not particularly limited. For example, if it is a flat plate shape, the shape seen from the plane may be a circle, an ellipse, a triangle, a quadrangle, a polygon, or other shapes.

Next, a tank type ultrasonic cleaning apparatus will be described as a second embodiment of the ultrasonic cleaning apparatus according to the present invention.
FIG. 2 is a schematic view showing a second embodiment of the ultrasonic cleaning apparatus according to the present invention.
The tank-type ultrasonic cleaning apparatus 20 includes a wafer carrier 21 serving as a substrate holding unit capable of holding a plurality of substrates W to be cleaned, and the vibration of the piezoelectric vibrator 25 by the substrate W held on the wafer carrier 21. A cleaning tank 22 for cleaning ultrasonic waves by propagating the liquid to the cleaning liquid 24, and an ultrasonic oscillator 23 for applying a high frequency voltage to a piezoelectric vibrator 25 attached to the outer wall of the cleaning tank 22 via a radiation plate 27. Have.
The piezoelectric vibrator 25 is a plate-shaped piezoelectric vibrator in which the vibration electrodes 26a and 26b are formed. The polarization axis P of the piezoelectric vibrator 25 is tilted at a desired angle with respect to the thickness direction T.

In the ultrasonic cleaning apparatus having a tank type cleaning means as described above, the plate-shaped piezoelectric vibrator 25 whose polarization axis P is inclined at a desired angle with respect to the thickness direction T is particularly effective as described above. To do.
If the piezo-electric vibrator is a diffusive flat-plate vibrator 45 as shown in FIG. 4, it is easy to join a plurality of vibrators to the radiation plate 27 because the vibrator has a flat plate shape. Since the ultrasonic vibration propagates in the direction in which it is diffused, it is possible to clean a wider area than the area of the piezoelectric vibrator.

In addition, even if it is a tank type ultrasonic cleaning apparatus, the piezoelectric vibrator is not limited to being a diffusion type flat plate vibrator as shown in FIG. In FIG. 2, the radiation plate 27 for mounting the vibrator is attached to the bottom surface of the outer wall of the cleaning tank 22, but the attachment position is not limited.
For example, when it is desired to obtain a cleaning effect particularly near the center of the substrate W, the converging flat plate vibrator 35 shown in FIG. 3 is attached to the side surface and the bottom surface of the outer wall of the cleaning tank 22. It is also possible to use a vibrator in which the converging point F is set near the center of the substrate W.
The shape of the piezoelectric vibrator to be used is limited to a flat plate shape from the viewpoint of device design, but the shape seen from the plane is not particularly limited. For example, if it is a flat plate shape, the shape seen from the plane may be a circle, an ellipse, a triangle, a quadrangle, a polygon, or other shapes.

Next, the piezoelectric vibrator of the present invention used in the ultrasonic cleaning apparatus of the first and second embodiments will be described in detail.
First, a first embodiment of a piezoelectric vibrator according to the present invention is a focusing plate vibrator as shown in FIG. FIG. 3 is a schematic view showing a focusing plate oscillator according to the present invention.
The converging flat plate vibrator 35 has vibration electrodes 36 a and 36 b on the front and back surfaces of the piezoelectric body 38. The vibration electrode 36a is a positive electrode, and the vibration electrode 36b is a negative electrode. And it vibrates by applying the high frequency voltage from a high frequency oscillator to vibration electrode 36a, 36b.
In particular, the converging flat plate vibrator 35 has a piezoelectric body 38 so that the ultrasonic vibration propagated at a desired point F in a medium in which vibration propagates (cleaning liquid when used in an ultrasonic cleaning apparatus) is focused. The polarization axis P is inclined with respect to the thickness direction T.

  In this way, if the polarization axis of the piezoelectric body itself is tilted so as to be focused, by applying a high frequency voltage thereto, the ultrasonic vibration is focused at a desired point in the propagated medium. At that point, the amplitude is maximized. As a result, when designing a device in which the cleaning ability can be utilized to the maximum and the direction of propagation of vibration is controlled, it can be designed in the same way as a conventional flat plate shape without being limited by the shape of the vibrator. Yes, you can keep that degree of freedom.

  Further, the focusing may be performed not on a point but on a desired line. FIG. 3 only shows a cross-sectional view of a piezoelectric vibrator in which vibration is focused on a point, but a plate-like piezoelectric vibrator in which vibration is focused on a desired line is a piezoelectric vibrator according to the present invention described later. The manufacturing method will be described in detail.

Next, the second embodiment of the piezoelectric vibrator according to the present invention is a diffusion type flat vibrator as shown in FIG. FIG. 4 is a schematic view showing a diffusion type flat plate vibrator according to the present invention.
The converging flat plate vibrator 45 has vibration electrodes 46 a and 46 b on the front and back surfaces of the piezoelectric body 48. The vibration electrode 46a is a positive electrode, and the vibration electrode 46b is a negative electrode. And it vibrates by applying the high frequency voltage from a high frequency oscillator to vibration electrode 46a, 46b.
In particular, the diffusion type flat plate resonator 45 has a polarization axis P of the piezoelectric body 48 so that the propagated ultrasonic vibration is diffused in a medium in which vibration is propagated (a cleaning liquid when used in an ultrasonic cleaning apparatus). It is inclined with respect to the thickness direction T.

  In this way, if the polarization axis of the piezoelectric body itself is inclined so as to diffuse from the beginning, by applying a high frequency voltage thereto, ultrasonic vibration is diffused in the propagated medium, and the vibration of the vibrator Vibration can be propagated in a wider range than the area. As a result, when designing a device in which the cleaning ability can be utilized to the maximum and the direction of propagation of vibration is controlled, it can be designed in the same way as a conventional flat plate shape without being limited by the shape of the vibrator. Yes, you can keep that degree of freedom.

  In particular, a vibrator that focuses vibrations at a desired point has conventionally had a spherical surface for propagating vibrations to a medium and has been difficult to join to a radiation plate. In the case of a flat plate vibrator or a diffusion type flat plate vibrator), the surface through which vibration is propagated to the medium is a flat surface. Therefore, it is easy to join a plurality of piezoelectric vibrators to a radiation plate, and Since the propagation direction of vibration is controlled in a desired direction, it is possible to produce an effect by vibration suitable for the application, compared to a conventional vibrator in which vibration propagates only in one direction.

Next, a method for manufacturing the piezoelectric vibrator will be described below with reference to the process flow of FIG.
FIG. 6 is a flowchart showing an example of a method for manufacturing a piezoelectric vibrator according to the present invention.

First, in the preparation step of step A, a plate-shaped piezoelectric body 38 is prepared.
The material of the piezoelectric body 38 to be prepared may be mainly made of a material such as lead zirconate titanate ceramic (PZT), lead titanate ceramic, lead niobate ceramic.
The shape of the piezoelectric body 38 may be a flat plate shape, and the shape viewed from the plane is not particularly limited, and may be a circle, a square, or a rectangle.

Next, in the temporary electrode step of step B, the temporary electrodes 66a and 66b for polarization are formed on the front and back surfaces of the prepared piezoelectric body 38. At this time, the temporary electrodes 66a and 66b for polarization are formed as temporary electrodes having a pattern so that the polarization axis P is inclined at a desired angle with respect to the thickness direction T. That is, when the temporary electrode is formed, an insulating portion is formed.
The temporary electrode may be formed by the same method as the method of forming the electrode on the vibrator. For example, an insulating pattern is masked in advance on the piezoelectric body 38 and a metal (eg, Ag) paste is applied. By applying a heat treatment at a temperature of about 1200 ° C., a temporary electrode can be formed.

Here, the temporary electrode pattern will be described.
FIG. 7 is a diagram illustrating an example of forming a temporary electrode pattern. FIG. 8 is a diagram illustrating an example of the propagation direction of vibration.
When the piezoelectric body is a circular flat plate, the temporary electrode 66a on the surface is plated with a metal that forms the temporary electrode on a portion that is concentrically hatched as in the pattern 71 of FIG. . When the vibration propagation direction is focused on one point on the cone as in the propagation direction 81 of FIG. 8, a pattern 71 having a width narrower than the width of the front temporary electrode pattern 66a is used as the rear temporary electrode 66b. What is necessary is just to form.
Conversely, when the vibration propagation direction is diffused as in the propagation direction 82 of FIG. 8, a pattern 71 having a width wider than the width of the front temporary electrode pattern 66a may be formed as the rear temporary electrode 66b.

When the piezoelectric body is square or rectangular and the vibration propagation direction is focused on one point on the cone as in the propagation direction 83 in FIG. 8, a temporary electrode and an insulating region are formed as in the pattern 72 in FIG. Then, a pattern 72 having a width narrower than the width of the front temporary electrode pattern 66a may be formed as the rear temporary electrode 66b.
On the contrary, when the vibration propagation direction is diffused as in the propagation direction 84 of FIG. 8, a pattern 72 having a width wider than the width of the temporary electrode pattern 66a on the front surface may be formed as the temporary electrode 66b on the back surface.

Further, when the piezoelectric body is square or rectangular and the vibration propagation direction is focused on one line as in the propagation direction 85 in FIG. 8, a temporary electrode and an insulating region are formed as in the pattern 73 in FIG. The pattern 73 having a width narrower than the width of the temporary electrode pattern 66a on the front surface may be formed as the temporary electrode 66b on the back surface.
Conversely, when the vibration propagation direction is diffused for each column as in the propagation direction 86 of FIG. 8, a pattern 73 having a width wider than the width of the temporary electrode pattern 66a on the front surface is formed as the temporary electrode 66b on the back surface. That's fine.

  These temporary electrode patterns may be formed in a pattern in which the polarization axis is inclined with respect to the thickness direction of the piezoelectric body so as to be focused or diffused to a desired point or line in the medium where the vibration caused by the piezoelectric vibrator propagates. In consideration of the direction in which vibration is desired to propagate, the thickness of the piezoelectric body, the size of the piezoelectric body, the distance to a desired point to be focused, etc., the width of the temporary electrode and the width of the insulating region may be determined as appropriate. .

  In this manner, by forming a pattern in which the polarization axis is inclined at a desired angle with respect to the thickness direction T in the piezoelectric body as a temporary electrode, the polarization axis of the piezoelectric vibrator can be A piezoelectric vibrator inclined with respect to the thickness direction of the piezoelectric body so as to be focused or diffused on a point or line can be manufactured.

Next, in the polarization step of Step C, a strong direct current electric field is applied to the temporary electrodes 66a and 66b formed on the front and back surfaces of the piezoelectric body 38 to subject the piezoelectric body to polarization. At that time, a DC strong electric field is individually applied to the temporary electrodes 66a and 66b formed on the front and back surfaces of the piezoelectric body one by one or two sets.
That is, when concentric temporary electrode patterns such as the patterns 71 and 72 in FIG. 7 are formed, polarization processing is sequentially performed one by one from the central temporary electrode toward the outer temporary electrode.
On the other hand, when a linear temporary electrode pattern is formed as in the pattern 73 of FIG. 7, the center of the piezoelectric body 38 is first formed from one central temporary electrode toward the outer temporary electrode. The part is polarized, and then two pairs are sequentially applied to the outer temporary electrodes.

  The strength of the DC voltage during the polarization treatment is preferably about 8 kV to 11 kV, but this value is only made of lead zirconate titanate ceramics (PZT) with a diameter of 25 mm and a thickness of about 5. This is an example in the case where a polarization process is applied to a 5 mm flat plate and circular piezoelectric body 38, and the current value may be appropriately determined depending on the material, size, thickness, etc. of the piezoelectric body.

Next, in the removal step of step D, the temporary electrodes 66a and 66b that have been subjected to the polarization treatment are removed from the front and back surfaces of the piezoelectric body.
As a method for removing the temporary electrode, a generally performed method such as etching or polishing can be applied. For example, in the case of etching, the temporary electrode can be removed by immersing the piezoelectric body after the polarization treatment in an etching tank filled with an aqueous nitric acid solution that removes the temporary electrode (Ag).

  Next, in the vibration electrode step of step E, the vibration electrodes 36a and 36b are formed on the front and back surfaces of the piezoelectric body 38 from which the temporary electrodes 66a and 66b have been removed. At that time, vibration electrodes are formed on the entire front surface and back surface of the piezoelectric body 38.

  In general, when forming a piezoelectric vibrator, an electrode for performing a polarization process and an electrode for applying a voltage to vibrate the vibrator are combined. It will not be removed. However, in the case of the present invention, a temporary electrode having a pattern was formed to incline the polarization axis from the thickness direction, but when applying a high frequency voltage to the vibrator as an actual product, for the purpose of vibrating all the polarized parts, Since it was necessary to apply an electric field to the entire surface of the piezoelectric body, the temporary electrode was removed in step D.

  The piezoelectric body 38 from which the temporary electrode has been removed is maintained in a polarized state even after the electric field by the temporary electrode is removed due to its ferroelectric properties. Here, when forming the vibrating electrode on the entire surface, If heat treatment is applied as in the case of forming the temporary electrode, the polarization state in which the polarization axis is inclined to a desired angle in the piezoelectric body is destroyed. Therefore, an electrode that is subjected to heat treatment at about 200 ° C. or higher. The forming method cannot be adopted.

Therefore, in the manufacturing method of the present invention, when the vibrating electrode is formed on the piezoelectric body after the polarization treatment, it is preferable to form the vibrating electrode by a method in which heat of 200 ° C. or higher is not applied to the piezoelectric body 38.
In particular, by forming the vibrating electrode by electroless plating, the vibrating electrode can be formed on the entire surface while maintaining a good polarization state of the already polarized piezoelectric body.

  A piezoelectric vibrator in which the polarization axis of the piezoelectric vibrator is simply inclined at a desired angle with respect to the thickness direction of the piezoelectric body by the above-described method of manufacturing a piezoelectric vibrator according to the present invention from step A to step E. In particular, the focusing type flat plate vibrator and the diffusion type flat plate vibrator introduced above can be manufactured.

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical idea of the invention.

1 is a schematic view showing a first embodiment of an ultrasonic cleaning apparatus according to the present invention. It is the schematic which shows 2nd Embodiment of the ultrasonic cleaning apparatus which concerns on this invention. It is the schematic which shows the focusing type flat plate vibrator which concerns on this invention. It is the schematic which shows the diffusion type flat plate vibrator which concerns on this invention. It is the schematic of the conventional focusing type piezoelectric vibrator, (a) is a concave spherical vibrator, (b) is a lens coupling type focusing vibrator. It is a flowchart which shows an example of the manufacturing method of the piezoelectric vibrator which concerns on this invention. It is a figure which shows the example of formation of a temporary electrode pattern. It is a figure which shows the example of the propagation direction of a vibration.

Explanation of symbols

10 ... Nozzle type ultrasonic cleaning device, 11 ... Substrate holding means,
12 ... Cleaning means (nozzles) 13, 23 ... High frequency oscillators 14, 24 ... Cleaning fluid,
15, 25 ... Piezoelectric vibrator (polar shape and polarization inclination),
16a, 16b, 26a, 26b, 36a, 36b, 46a, 46b ... vibrating electrodes,
17, 27 ... diaphragm, 20 ... tank type ultrasonic cleaning device,
21 ... Substrate holding means (wafer carrier), 22 ... Cleaning means (cleaning tank),
35 ... Converging type flat plate vibrator, 38, 48 ... Piezoelectric body,
45 ... diffusion type flat plate vibrator, 66a ... temporary electrode on the front surface, 66b ... temporary electrode on the back surface,
71-73 ... Temporary electrode pattern, 81-86 ... Propagation direction of vibration,
F: Focusing point, P: Polarization axis, T: Thickness direction of piezoelectric body, W: Substrate.

Claims (9)

At least a substrate holding means for holding the substrate of the object to be cleaned, a cleaning means for ultrasonically cleaning the substrate held by the substrate holding means by propagating the vibration of the piezoelectric vibrator to the cleaning liquid, and the piezoelectric vibrator of the cleaning means In an ultrasonic cleaning apparatus having an ultrasonic oscillator that applies a high frequency voltage to
The piezoelectric vibrator is a plate-shaped piezoelectric vibrator in which a vibrating electrode is formed,
The ultrasonic cleaning apparatus, wherein the flat plate-shaped piezoelectric vibrator has a polarization axis inclined at a desired angle with respect to a thickness direction.   The piezoelectric vibrator is a converging plate vibrator in which an inclination with respect to a thickness direction of the polarization axis is controlled so that vibration propagated to the cleaning liquid is converged to a desired point or line. 2. The ultrasonic cleaning apparatus according to 1.   2. The ultrasonic wave according to claim 1, wherein the piezoelectric vibrator is a diffusion type flat plate vibrator in which an inclination with respect to a thickness direction of the polarization axis is controlled so that vibrations propagated to the cleaning liquid are diffused. Cleaning device.   The said washing | cleaning means is equipped with the nozzle which accommodates the said piezoelectric vibrator, This nozzle discharges a washing | cleaning liquid toward a board | substrate, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Ultrasonic cleaning device.   The said washing | cleaning means is equipped with the washing tank which accommodates the said washing | cleaning liquid, and the said piezoelectric vibrator is attached to the outer wall of this washing tank via a radiation plate. 4. The ultrasonic cleaning apparatus according to any one of 3 above. A plate-shaped piezoelectric vibrator that has vibration electrodes on the front and back surfaces of a plate-shaped piezoelectric body and vibrates by applying a high-frequency voltage to the vibration electrode,
A piezoelectric vibration characterized in that a polarization axis of the piezoelectric vibrator is inclined with respect to a thickness direction of the piezoelectric body so as to be focused or diffused on a desired point or line in a medium through which the vibration propagates. Child. At least a preparation step of preparing a plate-shaped piezoelectric body,
A temporary electrode step of forming temporary electrodes for polarization on the front and back surfaces of the piezoelectric body;
A polarization step of applying a DC strong electric field to the temporary electrode to polarize the piezoelectric body;
Removing the temporary electrode from the front and back surfaces of the piezoelectric body;
A method of manufacturing a plate-shaped piezoelectric vibrator including a vibrating electrode step of forming a vibrating electrode on the front and back surfaces of the piezoelectric body,
During the temporary electrode step, a temporary electrode having a pattern is formed on the front and back surfaces of the piezoelectric body so that the polarization axis of the piezoelectric vibrator is inclined at a desired angle with respect to the thickness direction.
During the polarization step, a DC strong electric field is individually applied to the temporary electrodes formed on the front and back surfaces of the piezoelectric body one by one or two sets,
A method of manufacturing a piezoelectric vibrator, comprising forming a vibrating electrode on the entire front surface and back surface of the piezoelectric body during the vibrating electrode step after the removing step.   The pattern of the temporary electrode is a pattern in which the polarization axis is inclined with respect to the thickness direction of the piezoelectric body so as to be focused or diffused to a desired point or line in the medium through which the vibration by the piezoelectric vibrator propagates. The method for manufacturing a piezoelectric vibrator according to claim 7, wherein:   The method for manufacturing a piezoelectric vibrator according to claim 7 or 8, wherein the vibration electrode is formed by electroless plating in the vibration electrode step.

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