JP2000107710A - Ultrasonic substrate treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate treatment apparatus of reduced variation in a cavitation area by ultrasonic waves and to attempt the uniform treatment of the substrate. SOLUTION: A substrate cleaning apparatus 1 is equipped with a cleaning bath 2, a boundary plate 7, and an ultrasonic oscillator 8. In the cleaning bath 2, a cleaning liquid is stored, and a substrate W to be cleaned is placed. The boundary plate 7 is interposed between the cleaning liquid in the cleaning bath 2 and an atmosphere above the solution 2. The ultrasonic oscillator 8 emits ultrasonic waves toward the boundary plate 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing apparatus utilizing ultrasonic waves, and more particularly, to a substrate processing apparatus which promotes peeling of adhered particles or cleaning of dirt by utilizing an impact force due to cavitation.

[0002]

2. Description of the Related Art In a wet apparatus for processing a thin substrate such as a glass substrate for liquid crystal display, a semiconductor wafer, and a printed board, various processing apparatuses using ultrasonic waves have been proposed and put into practical use. For example, as an apparatus for generating a standing wave in a processing liquid by an ultrasonic wave of about 100 kHz or less and using a cavitation action to process a substrate, a substrate immersed in a cleaning tank is subjected to a cavitation action to remove organic dirt and inorganic dirt. There is a substrate cleaning apparatus for cleaning while promoting dissolution and dispersion in a substrate, and a substrate peeling apparatus for promoting separation of adhered particles by cavitation.

In these apparatuses, an ultrasonic oscillator is disposed in a tank in which a processing liquid such as a cleaning liquid or an organic solvent is stored, and the ultrasonic oscillator oscillates ultrasonic waves toward the liquid surface. here,
The distance h between the ultrasonic transducer and the liquid surface is set to the following value in accordance with the wavelength λ of the oscillating ultrasonic wave. h = (2n + 1) λ / 4 (where n is an arbitrary natural number) Then, a standing wave is generated in the processing liquid by the ultrasonic wave directed to the liquid surface and the ultrasonic wave reflected by the liquid surface. This standing wave is generated from the oscillating portion of the ultrasonic vibrator and the liquid level by ｛(2n-1) λ
It is a wave that is hungry at a position below by｝ and has nodes on the liquid surface. The region where the antinode of the standing wave is located is a so-called cavitation region, and the processing of the substrate disposed in this region is promoted by the cavitation action.

[0004]

As described above, in a substrate processing apparatus utilizing ultrasonic waves, a thin plate-like substrate is disposed in a cavitation area to promote the processing. The liquid level may fluctuate due to operations such as carrying in and out. When the liquid level fluctuates in this way, the position and angle of reflection of the ultrasonic wave on the liquid level become unstable, and the position of the cavitation area fluctuates. When the cavitation area fluctuates, the magnitude of the cavitation action on each part of the substrate becomes uneven, and as a result, uniform processing of the substrate cannot be ensured.

An object of the present invention is to provide a substrate processing apparatus in which a cavitation area, which is a position of an antinode of a standing wave in a processing solution caused by an ultrasonic wave, has a small variation, and to uniformly process a substrate.

[0006]

According to a first aspect of the present invention, an ultrasonic substrate processing apparatus includes a processing liquid tank, a boundary plate, and an ultrasonic vibrator. A processing liquid is stored in the processing liquid tank, and a substrate to be processed is accommodated therein. The boundary plate is disposed between the processing liquid in the processing liquid tank and the atmosphere. The ultrasonic oscillator oscillates ultrasonic waves toward the boundary plate.

In this apparatus, the ultrasonic waves oscillated from the ultrasonic vibrator are reflected at the boundary between the boundary plate and the processing solution or at the boundary between the boundary plate and the atmosphere. If a standing wave is generated in the processing liquid by the reflected ultrasonic wave and the ultrasonic wave oscillated from the ultrasonic transducer, the substrate is accommodated and arranged in the cavitation area which is the antinode of the standing wave. Thus, the processing of the substrate can be promoted. Here, since the ultrasonic wave is oscillating toward the boundary plate, by making the distance between the ultrasonic transducer and the boundary plate correspond to the wavelength of the ultrasonic wave,
A standing wave is generated in the processing liquid.

In this apparatus, a boundary plate is disposed between the processing liquid and the atmosphere to stabilize the boundary between the processing liquid and the atmosphere. Ultrasonic waves are reflected more stably and fluctuations in the cavitation area are reduced, as compared with an apparatus in which ultrasonic waves are reflected by a simple boundary surface. Thereby, the uniformity of the substrate processing is improved as compared with the related art.

Since the reflection of the ultrasonic waves occurs at the boundary between the boundary plate and the processing solution or at the boundary between the boundary plate and the atmosphere, in order to suppress the phase shift of the reflected ultrasonic waves,
Reduce the thickness of the boundary plate so that the boundary between the boundary plate and the processing liquid and the boundary between the boundary plate and the atmosphere are close to each other, or reflect most of the ultrasonic waves at the boundary between the boundary plate and the processing liquid. Alternatively, it is desirable that the ultrasonic wave is reflected at the boundary surface between the boundary plate and the atmosphere without substantially reflecting the ultrasonic wave at the boundary surface between the boundary plate and the processing solution.

An ultrasonic substrate processing apparatus according to a second aspect is the apparatus according to the first aspect, wherein the boundary plate is disposed above the processing liquid. Here, since the boundary plate is disposed above the processing liquid, evaporation of the processing liquid can be suppressed. Thereby, particularly in the case of an apparatus that performs substrate processing using a high-temperature processing liquid, the amount of the processing liquid to be used is suppressed, and the running cost is reduced.

An ultrasonic substrate processing apparatus according to a third aspect is the apparatus according to the second aspect, wherein the lower surface of the boundary plate is inclined with respect to a horizontal plane. Here, when the processing liquid is filled in the processing liquid tank and the processing liquid is filled up to the boundary plate or when air enters between the boundary plate and the processing liquid, the lower surface of the boundary plate is inclined. Gas such as air that has entered between the plate and the processing liquid rises along the lower surface of the boundary plate. Since the gas between the boundary plate and the processing liquid is removed as described above, the reflection of the ultrasonic wave at the boundary plate is performed well.

An ultrasonic substrate processing apparatus according to a fourth aspect is the apparatus according to any one of the first to third aspects, wherein the boundary plate is a glass plate. The reflection of ultrasonic waves occurs at the boundary between the boundary plate and the processing solution or at the boundary between the boundary plate and the atmosphere. Here, the boundary plate is a glass plate, and at the boundary between the glass plate and the processing solution, the ultrasonic wave is reflected. Since most of the sound waves pass without being reflected, most of the ultrasonic waves are reflected at the interface between the glass plate and the atmosphere. Thereby, the reflected ultrasonic waves are more stable, and the fluctuation of the cavitation area is smaller.

According to a fifth aspect of the present invention, there is provided an ultrasonic substrate processing apparatus according to any one of the first to fourth aspects, wherein the substrate is provided with an ultrasonic oscillator oscillated from an ultrasonic vibrator in a processing liquid tank. In addition, it is arranged at the position of the antinode of the standing wave generated in the processing liquid in the processing tank by the ultrasonic wave oscillated from the ultrasonic transducer and reflected by the boundary plate. Here, since the substrate is arranged at the position of the antinode of the standing wave, that is, at the cavitation area, the efficiency of the substrate processing is improved as compared with the case where the substrate is arranged at another position. In addition, since the reflected ultrasonic waves are stabilized by the installation of the boundary plate, the cavitation area has little fluctuation, and the substrate can be easily arranged in the cavitation area.

An ultrasonic substrate processing apparatus according to a sixth aspect includes a processing liquid tank, an ultrasonic vibrator, and an ultrasonic reflecting plate. A processing liquid is stored in the processing liquid tank, and a substrate to be processed is accommodated therein. The ultrasonic oscillator oscillates ultrasonic waves toward the substrate. The ultrasonic reflecting plate is disposed on the side of the substrate opposite to the ultrasonic transducer side in the processing liquid tank. This ultrasonic reflector is arranged in parallel with the ultrasonic transducer.

In this device, the ultrasonic wave oscillated from the ultrasonic vibrator is reflected by the ultrasonic reflecting plate. If a standing wave is generated in the processing liquid by the reflected ultrasonic wave and the ultrasonic wave oscillated from the ultrasonic transducer, the substrate is accommodated and arranged in the cavitation area which is the antinode of the standing wave. Thus, the processing of the substrate can be promoted. Here, since the ultrasonic vibrator and the ultrasonic reflecting plate are parallel to each other, the distance between the ultrasonic vibrator and the ultrasonic reflecting plate corresponds to the wavelength of the ultrasonic wave, so that the standing wave is generated in the processing liquid. appear.

In this apparatus, an ultrasonic reflecting plate is provided in the processing tank instead of the liquid surface which may be wavy as in the prior art.
Ultrasonic waves are oscillated on this to reflect the ultrasonic waves. For this reason, the reflection of the ultrasonic wave is stabilized, and the fluctuation of the cavitation area is reduced as compared with the related art. Thereby, the uniformity of the substrate processing is improved as compared with the related art. In order to reduce the amount of ultrasonic waves that pass through the ultrasonic reflecting plate without being reflected by the ultrasonic reflecting plate, it is desirable that the ultrasonic reflecting plate be made so that ultrasonic waves (sound waves) do not pass as much as possible.

An ultrasonic substrate processing apparatus according to a seventh aspect is the apparatus according to the sixth aspect, wherein the ultrasonic reflection plate has a cavity therein. Here, since gas is present inside the ultrasonic reflector, ultrasonic waves not reflected at the interface between the ultrasonic reflector and the processing liquid are also reflected at the interface between the solid and the gas of the ultrasonic reflector. Is done. As described above, since the ultrasonic wave is surely reflected by the ultrasonic reflecting plate, the efficiency of the substrate processing is improved.

Since the reflection of the ultrasonic wave occurs at the boundary between the processing liquid and the solid of the ultrasonic reflection plate or the boundary between the solid and the gas of the ultrasonic reflection plate, the phase shift of the reflected ultrasonic wave is suppressed. For this reason, reduce the thickness of the solid part of the ultrasonic reflector, or use an ultrasonic reflector that can easily pass ultrasonic waves through the solid at the interface between the treatment liquid and the solid of the ultrasonic reflector. It is desirable that the ultrasonic waves be reflected at the interface between the solid and the gas of the ultrasonic reflection plate with little reflection.

[0019]

[First Embodiment] FIG. 1 shows a substrate cleaning apparatus (ultrasonic substrate processing apparatus) according to one embodiment of the present invention.
Shown in The substrate processing apparatus 1 generates a cavitation area in the cleaning tank 2 by ultrasonic waves oscillated from the ultrasonic vibrator 8 while circulating the cleaning liquid in the cleaning tank 2, and transports the substrate W in the cavitation area. In this case, the substrate W is cleaned by adding a cavitation effect to the operation of the cleaning liquid. This apparatus 1 is, for example, an apparatus provided in a cleaning process in a series of production lines for a glass substrate for liquid crystal display.

<Structure> The substrate processing apparatus 1 mainly includes a cleaning tank 2, a transport mechanism, an ultrasonic vibrator 8, and a boundary plate 7. The cleaning tank (treatment liquid tank) 2 has a carry-in port and a carry-out port (not shown), a cleaning liquid supply hole opened on the bottom surface to which the cleaning liquid supply pipe 3 is connected, and an overflow pipe opened at the upper side wall and connected to the overflow pipe 4. A hole is formed. The cleaning liquid is always supplied to the cleaning tank 2 by a cleaning liquid supply pipe 3, and the cleaning liquid overflows by an overflow pipe 4. Thereby, the liquid level S of the cleaning tank 2 is generally maintained at the level shown in FIG. The material (resin or metal) of the cleaning tank is determined by the cleaning liquid used, but the cleaning tank 2 is made of resin.

The transport mechanism has a plurality of transport rollers including a rotary shaft 6a disposed in the cleaning tank 2 and a stepped roller 6b fixed to the rotary shaft 6a. The rotation shaft 6a of these transport rollers is rotated by a motor (not shown), so that the substrate W supported by the stepped rollers 6b of the transport rollers is transported in the cleaning tank 2. The rotating shaft 6a is rotatably supported on the side wall of the cleaning tank 2.
Further, the substrate W is carried into the cleaning tank 2 from the entrance of the cleaning tank 2 by the transport mechanism, and is carried out of the cleaning tank 2 from the exit of the cleaning tank 2. The substrate W is a thin plate-shaped glass substrate having a thickness of 1 mm or less.

The ultrasonic vibrator 8 oscillates ultrasonic waves obliquely upward from the ultrasonic oscillation surface 8a, which is the upper surface, perpendicularly to the ultrasonic oscillation surface 8a. Are located in The boundary plate 7 is a glass plate that covers an upper opening of the cleaning tank 2, and its periphery is water-tightly fixed to a side wall and an end wall of the cleaning tank 2. Therefore, cleaning tank 2
1, the upper surface 7a of the boundary plate 7 is in contact with the atmosphere above the cleaning tank 2, and most of the lower surface 7b of the boundary plate 7 is in the cleaning tank 2. Contact with cleaning solution. Lower surface 7b of boundary plate 7
Among the parts, the part irradiated with the ultrasonic wave oscillated from the ultrasonic vibrator 8 is in contact with the cleaning liquid in the cleaning tank 2 as shown in FIG.

The cleaning tank 2, the rotating shaft 6a of the transfer mechanism, the ultrasonic oscillation surface 8a of the ultrasonic vibrator 8, the boundary plate 7, and the substrate W transferred in the cleaning tank 2 are shown in FIG. As shown, it is inclined by an angle θ with respect to the horizontal plane H.
With such an inclined arrangement, gas is less likely to accumulate in the contact portion between the lower surface 7b of the boundary plate 7 to which the ultrasonic wave is applied and the cleaning liquid in the cleaning tank 2. The angle θ is
The angle may be larger than 0 °, and even if the angle θ is 90 °, it can be realized as an apparatus if the transport mechanism is established.

Next, the relative positions of the ultrasonic vibrator 8, the boundary plate 7, and the transport roller for transporting the substrate W will be described. First, in order to match the phase of the ultrasonic wave oscillated upward from the ultrasonic vibrator 8 and the ultrasonic wave reflected by the boundary plate 7 and directed downward, a node of the amplitude distribution of the ultrasonic wave indicated by a dotted line in FIG. (The position where the amplitude becomes 0) comes to the upper surface 7a of the boundary plate 7. Here, the distance (m + n) between the ultrasonic oscillation surface 8a and the upper surface 7a of the boundary plate 7 is set to be longer in consideration of the fact that the ultrasonic oscillation surface 8a of the ultrasonic transducer 8 becomes an antinode of the ultrasonic amplitude distribution. It is set to 0.75 times the wavelength λ of the sound wave. The distance (m + n) may be any value (h) determined by the following equation.

H = (2n + 1) λ / 4 (where n is an arbitrary natural number) The substrate W to be conveyed is located at the antinode of the amplitude distribution where the amplitude of the ultrasonic wave is large (the position where the amplitude is maximum). like,
Arrange the transport rollers. Here, as shown in FIG.
The distance m from the upper surface 7a of the boundary plate 7 to the substrate W is 0.25 times the wavelength λ of the ultrasonic wave, and the distance n from the substrate W to the ultrasonic oscillation surface 8a is 0.5 times the wavelength λ. A transport roller is provided.

The ultrasonic wave oscillated from the ultrasonic transducer 8 is
The frequency has a unique wavelength. This device 1
In order to generate cavitation by ultrasonic waves, ultrasonic waves having a frequency of about 100 kHz or less are oscillated. For example, if the cleaning liquid is pure water and a 40 kHz ultrasonic wave is oscillated, the ultrasonic waves transmitted through the cleaning liquid Wavelength λ
Is about 36 mm. In this case, the distance m in FIG. 1 is about 9 mm, and the distance n in FIG. 1 is about 18 mm. In this embodiment, in order to facilitate understanding, the distance n from the substrate W to the ultrasonic oscillation surface 8a is set to be 0.5 times the wavelength λ. Is not satisfied, the distance n may be set to a natural number multiple of 0.5 times the wavelength λ. That is, even if the distance m is 9 mm and the distance n is 54 mm, the phase of the ultrasonic wave oscillated from the ultrasonic transducer 8 and the ultrasonic wave reflected by the boundary plate 7 match, and the substrate W is located on the antinode of the amplitude distribution of the ultrasonic wave. Will be located.

<Operation> In the present apparatus 1, the ultrasonic wave oscillated from the ultrasonic vibrator 8 is applied to the lower surface 7b of the boundary plate, which is the boundary surface between the boundary plate 7 and the cleaning liquid, or the boundary between the boundary plate 7 and the atmosphere. The light is reflected on the upper surface 7a of the boundary plate 7, which is a surface. Since a standing wave (amplitude distribution is indicated by a dotted line in FIG. 1) is generated in the cleaning liquid by the reflected ultrasonic wave and the ultrasonic wave oscillated from the ultrasonic vibrator 8, this is the position of the antinode of the standing wave. Cavitation acts on the substrate W placed and transported in the cavitation area, and the cleaning process of the substrate W with the cleaning liquid is promoted.

The reflection of the ultrasonic wave at the boundary plate 7 occurs on the lower surface 7b of the boundary plate 7 or on the upper surface 7a of the boundary plate 7, but here, the boundary plate 7 is a glass plate, and the boundary between the glass plate and the cleaning liquid is formed. Since most of the ultrasonic waves pass through the lower surface 7b, which is a boundary surface, without being reflected, most of the ultrasonic waves are reflected by the upper surface 7a. Therefore, as described above, the distance m and the distance n are set with reference to the upper surface 7a.

<Features of the present apparatus> In the present apparatus 1, the cleaning tank 2
The boundary plate 7 is arranged between the cleaning liquid and the atmosphere in the inside to stabilize the boundary between the cleaning liquid and the atmosphere.
Is reflected on the upper surface 7a, the reflection of the ultrasonic wave is stabilized, and the degree of phase matching between the ultrasonic wave oscillated from the ultrasonic vibrator 8 and the reflected ultrasonic wave is increased. Thereby, the fluctuation of the cavitation area is reduced, and the substrate W
Has improved the uniformity of the cleaning process.

Further, in the present apparatus 1, since the upper opening of the cleaning tank 2 is covered by the boundary plate 7, evaporation of the cleaning liquid is suppressed. Further, in the present apparatus 1, since the boundary plate 7 and the like are inclined with respect to the horizontal plane H, when the cleaning liquid is put into the cleaning tank 2 and the cleaning tank 2 is filled with the cleaning liquid, or between the boundary plate 7 and the cleaning liquid. When air enters, the air that has entered between the boundary plate 7 and the cleaning liquid rises along the lower surface 7b of the boundary plate 7. Thereby, the gas between the boundary plate 7 and the cleaning liquid is removed, so that the reflection of the ultrasonic waves below the boundary plate 7 is suppressed, and the reflection of the ultrasonic waves is reliably performed by the boundary plate 7. Can be made.

[Second Embodiment] FIG. 2 shows a substrate cleaning apparatus (ultrasonic substrate processing apparatus) according to an embodiment of the present invention.
The substrate processing apparatus 11 is an apparatus that generates a cavitation area in the cleaning tank 12 by ultrasonic waves oscillated from the ultrasonic vibrator 18 while circulating the cleaning liquid in the cleaning tank 12, and transports the substrate W in the cavitation area. In this case, the substrate W is cleaned by adding a cavitation effect to the operation of the cleaning liquid. The apparatus 11 is, for example, an apparatus provided in a cleaning process in a series of manufacturing lines for a glass substrate for liquid crystal display.

<Structure> The substrate processing apparatus 11 mainly includes
It comprises a cleaning tank 12, a transport mechanism, an ultrasonic oscillator 18, and a boundary plate 17. Cleaning tank (treatment liquid tank) 12
Are formed with a carry-in port and a carry-out port (not shown), a cleaning liquid supply hole opened in the bottom face to which the cleaning liquid supply pipe 13 is connected, and an overflow tank 14 opened outside the upper part of the side wall. The cleaning liquid is constantly supplied to the cleaning tank 12 by a cleaning liquid supply pipe 13, and the cleaning liquid overflowing from the side wall flows into the overflow tank 14. As a result, the liquid level in the cleaning tank 12 is kept substantially at the level shown in FIG. In addition,
The material (resin or metal) of the cleaning tank is determined depending on the cleaning liquid used. The cleaning tank 12 is made of resin.

The transport mechanism includes a rotating shaft 16a disposed in the cleaning tank 12 and the stepped roller 1 fixed thereto.
6b. The substrate W supported by the stepped roller 16b of the transport roller is transported in the cleaning tank 12 by rotating the rotating shaft 16a of the transport roller by a motor (not shown). The rotating shaft 16a is rotatably supported on the side wall of the cleaning tank 12. Further, the substrate W is carried into the cleaning tank 12 from the entrance of the cleaning tank 12 by the transfer mechanism, and is carried out of the cleaning tank 12 from the exit of the cleaning tank 12. The substrate W is a thin plate-shaped glass substrate having a thickness of 1 mm or less.

The ultrasonic vibrator 18 oscillates ultrasonic waves vertically upward from the ultrasonic oscillating surface 18a, which is the upper surface, and is arranged near the bottom of the cleaning tank 12. Boundary plate 1
Reference numeral 7 denotes a glass plate that substantially covers the upper opening of the cleaning tank 12. In the state shown in FIG. 2 in which the boundary plate 17 overflows by storing the cleaning liquid in the cleaning tank 12,
The upper surface 17a of the boundary plate 17 is in contact with the atmosphere above the cleaning tank 12, and the lower surface 17b of the boundary plate 17 is in contact with the cleaning liquid in the cleaning tank 12. A protection plate 19 is fixed around the boundary plate 17 so that the cleaning liquid does not enter above the boundary plate 17 and accumulate on the upper surface 17a.

The cleaning tank 12, the rotating shaft 16a of the transfer mechanism, and the ultrasonic oscillation surface 1 of the ultrasonic vibrator 18 are used.
As shown in FIG. 2, the substrate 8 </ b> A, the boundary plate 17, and the substrate W transported in the cleaning tank 12 are arranged horizontally and parallel to each other. Next, the ultrasonic vibrator 18, the boundary plate 17,
The relative positions of the transport rollers that transport the substrate W will be described.

First, in order to match the phases of the ultrasonic wave oscillated vertically upward from the ultrasonic transducer 18 and the ultrasonic wave reflected by the boundary plate 17 and directed downward, the amplitude of the ultrasonic wave indicated by a dotted line in FIG. The node of the distribution (the position where the amplitude becomes 0) is set to be on the upper surface 17a of the boundary plate 17. In this case, the distance (m + n) between the ultrasonic oscillation surface 18a and the upper surface 17a of the boundary plate 17 is set to be longer in consideration of the fact that the ultrasonic oscillation surface 18a of the ultrasonic transducer 18 becomes an antinode of the amplitude distribution of the ultrasonic wave. It is set to 0.75 times the wavelength λ of the sound wave. The distance (m + n) may be any value (h) determined by the following equation. h = (2n + 1) λ / 4 (where n is an arbitrary natural number) Then, the substrate W conveyed is located at the antinode of the amplitude distribution where the amplitude of the ultrasonic wave is large (the position where the amplitude is maximum).
Arrange the transport rollers. Here, as shown in FIG.
When the distance m from the upper surface 17a of the boundary plate 17 to the substrate W is 0.25 times the wavelength λ of the ultrasonic wave, the ultrasonic oscillation surface 1
The transport rollers are arranged so that the distance n to 8a is 0.5 times the wavelength λ.

<Operation> In the present apparatus 11, the ultrasonic vibrator 1
The ultrasonic wave oscillated from 8 is reflected on the lower surface 17b of the boundary plate 17 which is the boundary surface between the boundary plate 17 and the cleaning liquid, or on the upper surface 17a of the boundary plate 17 which is the boundary surface between the boundary plate 17 and the atmosphere. The reflected ultrasonic wave and ultrasonic vibrator 18
Standing wave in the cleaning solution by ultrasonic waves oscillated from
, The amplitude distribution is indicated by a dotted line), the cavitation acts on the substrate W which is disposed and transported in the cavitation area which is the position of the antinode of the standing wave,
The cleaning process of the substrate W with the cleaning liquid is promoted.

The reflection of the ultrasonic wave at the boundary plate 17 is caused by the lower surface 17b of the boundary plate 17 or the upper surface 17a of the boundary plate 17.
However, in this case, most of the ultrasonic waves pass through the lower surface 17b, which is a boundary surface between the glass plate and the cleaning liquid, without being reflected. Therefore, most of the ultrasonic waves are reflected by the upper surface 17a. I do. Therefore, as described above, the distance m and the distance n are set with reference to the upper surface 17a.

<Characteristics of the present apparatus> In the present apparatus 11, a boundary plate 17 is disposed between the cleaning liquid and the atmosphere in the cleaning tank 12 to stabilize the boundary between the cleaning liquid and the atmosphere. Since the light is reflected on the upper surface 17 a of the ultrasonic wave 17, the reflection of the ultrasonic wave is stabilized, and the degree of phase matching between the ultrasonic wave oscillated from the ultrasonic vibrator 18 and the reflected ultrasonic wave is increased. Thereby, the fluctuation of the cavitation area is reduced, and the uniformity of the cleaning process of the substrate W is improved.

Further, in the present apparatus 11, since the upper opening of the cleaning tank 2 is substantially covered by the boundary plate 17, the evaporation of the cleaning liquid is suppressed. [Third Embodiment] FIG. 3 shows a substrate cleaning apparatus (ultrasonic substrate processing apparatus) according to one embodiment of the present invention. The substrate processing apparatus 21 irradiates the cleaning tank 22 with ultrasonic waves oscillated from the ultrasonic vibrator 28 while circulating the cleaning liquid in the cleaning tank 22.
A device for generating a cavitation area in the inside and transporting the substrate W in the cavitation area, and performs a cleaning process on the substrate W by adding a cavitation action to the action of the cleaning liquid. The apparatus 21 is, for example, an apparatus provided in a cleaning process in a series of manufacturing lines for a glass substrate for liquid crystal display.

<Structure> The substrate processing apparatus 21 mainly includes
The cleaning tank 22 includes a cleaning tank 22, a transport mechanism, an ultrasonic vibrator 28, and a reflection plate 27. Cleaning tank (treatment liquid tank) 22
Are formed with a carry-in port and a carry-out port (not shown), a cleaning liquid supply hole opened in the bottom surface to which the cleaning liquid supply pipe 23 is connected, and an overflow tank 24 opened outside the upper part of the side wall. The cleaning liquid is always supplied to the cleaning tank 22 by a cleaning liquid supply pipe 23, and the cleaning liquid overflowing from the side wall flows into the overflow tank 24. As a result, the liquid level in the cleaning tank 22 is kept substantially at the level shown in FIG. In addition,
The material (resin or metal) of the cleaning tank is determined depending on the cleaning liquid used. The cleaning tank 22 is made of resin.

The transport mechanism includes a rotating shaft 26a disposed in the cleaning tank 22 and the stepped roller 2 fixed thereto.
6b. The substrate W supported by the stepped roller 26b of the transport roller is transported in the cleaning tank 22 by rotating the rotation shaft 26a of the transport roller by a motor (not shown). The rotating shaft 26a is rotatably supported on the side wall of the cleaning tank 22. Further, the substrate W is carried into the cleaning tank 22 from the entrance of the cleaning tank 22 by the transport mechanism, and is carried out of the cleaning tank 22 from the exit of the cleaning tank 22. The substrate W is a thin plate-shaped glass substrate having a thickness of 1 mm or less.

The ultrasonic vibrator 28 oscillates ultrasonic waves vertically downward from the ultrasonic oscillation surface 28a which is the lower surface, and the ultrasonic oscillation surface 28a is immersed in the cleaning liquid above the cleaning tank 22. (See FIG. 3). The reflection plate (ultrasonic reflection plate) 27 is disposed below the cleaning tank 22 and below the substrate W transferred by the transfer mechanism.
It is composed of a resin lower member 71 and a glass plate 72, and has gas in the internal space (cavity) 27a. The lower member 71 extends upward from the bottom surface and four sides around the bottom surface.
With two sides. The glass plate 72 includes the lower member 7.
It is watertightly fixed to the upper part of the side surface of one. This reflector 2
7 is positioned at a predetermined position by the bottom surface of the lower member 71 being supported on the bottom surface of the washing tank 22 by the plurality of foot members 29.

The cleaning tank 22, the rotary shaft 26a of the transfer mechanism, and the ultrasonic oscillation surface 2 of the ultrasonic vibrator 28 are used.
As shown in FIG. 3, the substrate 8A, the reflection plate 27, and the substrate W conveyed in the cleaning tank 22 are arranged horizontally and parallel to each other. Next, the ultrasonic transducer 28, the reflection plate 27,
The relative positions of the transport rollers that transport the substrate W will be described.

First, in order to match the phases of the ultrasonic wave oscillated vertically downward from the ultrasonic transducer 28 and the ultrasonic wave reflected by the reflector 27 and moving upward, the amplitude of the ultrasonic wave indicated by the dotted line in FIG. The nodes of the distribution (positions where the amplitude becomes 0) are located on the lower surface of the glass plate 72 of the reflection plate 27. Here, considering that the ultrasonic oscillation surface 28a of the ultrasonic transducer 28 becomes an antinode of the amplitude distribution of the ultrasonic wave, the ultrasonic oscillation surface 28a
a and the distance between the lower surface of the glass plate 72 of the reflection plate 27 (m +
n) is set to 0.75 times the wavelength λ of the ultrasonic wave. The distance (m + n) may be any value (h) determined by the following equation.

H = (2n + 1) λ / 4 (where n is an arbitrary natural number) The substrate W to be conveyed is located at the antinode of the amplitude distribution where the amplitude of the ultrasonic wave is large (the position where the amplitude is maximum). like,
Arrange the transport rollers. Here, as shown in FIG.
The distance m from the lower surface of the glass plate 72 of the reflection plate 27 to the substrate W is 0.25 times the ultrasonic wavelength λ, and the distance n from the substrate W to the ultrasonic oscillation surface 28a is 0.5 times the wavelength λ. The transport rollers are arranged as shown in FIG.

<Operation> In the present apparatus 21, the ultrasonic vibrator 2
The ultrasonic wave oscillated from the upper surface of the glass plate 72, which is the boundary surface between the reflector 27 and the cleaning liquid,
The light is reflected on the lower surface of the glass plate 72, which is the boundary surface between the gas and the gas in the internal space 27a of the reflection plate 27. Since a standing wave (amplitude distribution is indicated by a dotted line in FIG. 3) is generated in the cleaning liquid by the reflected ultrasonic wave and the ultrasonic wave oscillated from the ultrasonic vibrator 28, this is the position of the antinode of the standing wave. Cavitation acts on the substrate W placed and transported in the cavitation area, and the cleaning process of the substrate W with the cleaning liquid is promoted.

The reflection of the ultrasonic wave by the reflection plate 27 occurs on the upper surface of the glass plate 72 or the lower surface of the glass plate 72. However, since the glass plate 72 transmits most of the ultrasonic wave without reflecting it, the ultrasonic wave is reflected. Most of the light is reflected on the lower surface of the glass plate 72. Therefore, as described above, the distance m and the distance n are set with reference to the lower surface of the glass plate 72.

<Features of the present apparatus> In the present apparatus 21, since the ultrasonic waves are reflected by the reflector 27 having a gas in the internal space 27a, almost all of the ultrasonic waves impinging on the reflector 27 are generated by the glass plate 72 and the gas. The light is reflected on the lower surface of the glass plate 72 which is the boundary surface. As described above, since the ultrasonic waves are surely reflected by the reflection plate 27, the cavitation action is enhanced, and the efficiency of the cleaning process of the substrate W is improved.

[Other Embodiments] (a) The present invention can be applied not only to cleaning of a glass substrate for liquid crystal display, but also to a cleaning apparatus of a semiconductor wafer, a printed circuit board or the like. (B) In each of the above embodiments, a glass plate is used to reflect ultrasonic waves at the boundary surface between the glass plate and the atmosphere (gas). May be used to reflect most of the ultrasonic waves at the interface with the cleaning liquid. Alternatively, a thinner metal plate or the like may be used instead of a glass plate so that the interface between the interface with the cleaning liquid and the interface with the atmosphere are close to each other and the reflected ultrasonic waves have almost the same phase. . (C) In the above embodiment, an example in which the present invention is applied to a substrate cleaning apparatus is described. However, the present invention can be applied to a substrate peeling apparatus that promotes peeling by ultrasonic waves.

[0051]

In the apparatus according to the present invention, a boundary plate is disposed between the processing liquid and the atmosphere to stabilize the boundary between the processing liquid and the atmosphere. Compared to a device that reflects ultrasonic waves at an unstable interface with the atmosphere, the reflection of ultrasonic waves is stable and the fluctuation of the cavitation region is reduced. Thereby, the uniformity of the substrate processing is improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a sectional view of a substrate cleaning apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a substrate cleaning apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a substrate cleaning apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

1,11,21 Substrate cleaning device (ultrasonic substrate processing device) 2,12,22 Cleaning tank (processing liquid tank) 7,17 Boundary plate 8,18,28 Ultrasonic transducer 27 Reflector (ultrasonic reflector) 27a Internal space (hollow)

Claims (7)

[Claims] 1. A processing liquid tank for accommodating a substrate, a boundary plate disposed between a processing liquid in the processing liquid tank and an atmosphere, and an ultrasonic oscillator oscillating ultrasonic waves toward the boundary plate. An ultrasonic substrate processing apparatus comprising: 2. The ultrasonic substrate processing apparatus according to claim 1, wherein said boundary plate is disposed above said processing liquid. 3. The ultrasonic substrate processing apparatus according to claim 2, wherein a lower surface of said boundary plate is inclined with respect to a horizontal plane. 4. The ultrasonic substrate processing apparatus according to claim 1, wherein said boundary plate is a glass plate. 5. In the processing liquid tank, a substrate is processed in the processing tank by ultrasonic waves oscillated from the ultrasonic vibrator and ultrasonic waves oscillated from the ultrasonic vibrator and reflected by a boundary plate. The ultrasonic substrate processing apparatus according to claim 1, wherein the ultrasonic substrate processing apparatus is disposed at a position of an antinode of a standing wave generated in the liquid. 6. A processing liquid tank for accommodating a substrate, an ultrasonic vibrator for oscillating ultrasonic waves toward the substrate, and the ultrasonic wave on a side of the processing liquid tank opposite to the ultrasonic vibrator side of the substrate. An ultrasonic substrate processing apparatus, comprising: an ultrasonic reflector arranged in parallel with a vibrator. 7. The ultrasonic substrate processing apparatus according to claim 6, wherein said ultrasonic reflecting plate has a cavity inside.