JPH06331429A - Ultrasonic wave intensity sensor and detection method - Google Patents

Abstract

PURPOSE:To effectively optimize relation a filtering flow, fluctuating speed, a board pitch and kinds of cleaning liquid in an ultrasonic cleaner and ultrasonic intensity which a board surface receives and efficiently make possible the removal of particulates adhering to a board to be cleaned without causing nonconformity such as damage of the board to be cleaned, poor cleaning thereof and cleaning nonuniformity. CONSTITUTION:An ultrasonic intensity sensor 1 has a base board 2 and piezoelectric elements 3 which are a plurality of ultrasonic intensity detection elements are arranged and formed on the surface of the base board 2. And a plurality of the ultrasonic intensity sensors 1 are arranged in an ultrasonic cleaning vessel for the purpose of three-dimensionally detecting ultrasonic intensity an ultrasonically cleaned board receives on the surface of the board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ultrasonic waves for detecting the ultrasonic intensity of an ultrasonic cleaning tank used for cleaning industrial materials and parts such as semiconductor devices, glass substrates for liquid crystal display elements, and optical lenses. The present invention relates to an intensity sensor and an ultrasonic intensity detection method.

[0002]

2. Description of the Related Art In general, ultrasonic cleaning is used, for example, for degreasing cleaning of an object to be cleaned with oil or fat, or for ultraprecision cleaning of semiconductor devices, glass substrates, etc., which require a clean surface. There is. Today, as semiconductor devices become highly integrated and glass substrates for liquid crystal display elements become larger,
While it is strongly desired to improve the ability of removing fine particles on the substrate in the substrate cleaning process, ultrasonic cleaning is drawing attention as one of the effective methods for removing the fine particles.

An example of an ultrasonic cleaning device for performing ultrasonic cleaning will be described with reference to FIG.
An ultrasonic cleaning tank 12 that stores the cleaning liquid 8 is provided, and an ultrasonic vibrator 14 that generates ultrasonic waves is arranged at the bottom of the ultrasonic cleaning tank 12. Further, a rocking basket 13 is provided inside the ultrasonic cleaning tank 12, and the cleaning liquid 8 is agitated by rocking the rocking basket 13. An overflow tank 12a is provided above the ultrasonic cleaning tank 12, and the bottom of the overflow tank 12a and the ultrasonic cleaning tank 12 are provided.
An overflow system is configured by connecting and via the communication pipe 15 in which the pump 16 and the filter 17 are provided. With this over-flow system, fine particles and the like in the cleaning liquid are efficiently filtered by the filter 17.
The clean cleaning liquid 8 after being filtered in (1) is returned to the ultrasonic cleaning tank 12 and is recycled.

When the substrate 9 to be cleaned is cleaned by using such an ultrasonic cleaning apparatus, a plurality of substrates 9 to be cleaned are held at predetermined intervals and the carrier 1 is a holding member for the substrate to be cleaned.
1 and put it in an oscillating car 13 provided in the ultrasonic cleaning tank 12. When the carrier 11 is put into the ultrasonic cleaning tank 12, the ultrasonic vibrator 14 operates,
Ultrasonic waves are emitted, and at the same time, rocking of the rocking car 13 starts. The ultrasonic waves emitted by the ultrasonic transducer 14 are
First, the cleaning liquid 8 propagates to the substrate 9 to be cleaned through the vibrated cleaning liquid 8 and is mainly eroded when the generated frequency is several tens of kHz or less, and when the megasonic region is reached, the vibration acceleration effect causes the cleaning to be performed. The fine particles and the like attached to the surface of the substrate 9 are dissociated. Ultrasonic cleaning tank 1 for dissociated particles
Ultrasonic cleaning tank 12 with 2 overflow systems
It is discharged to the outside and is efficiently captured and filtered by the filter 17 to be removed.

By the way, when the fine particles and the like adhering to the substrate 9 to be cleaned are removed by the ultrasonic cleaning as described above, from the viewpoint of removing the fine particles and the like, the filtration flow rate of the over-flow system and the shaking of the rocking basket 13 are considered. It is desirable that the relationship between the moving speed, the substrate pitch of the substrate 9 to be cleaned, the type of the cleaning liquid 8 and the ultrasonic intensity received by the surface of the substrate 9 to be cleaned be optimized. In the case of a glass substrate for a liquid crystal display element, it has a size of about 300 × 400 mm square at present, and it may be further enlarged in the future, and a large substrate of about 500 × 600 mm square may be used. As the size of the cleaning substrate 9 increases, it is desired to optimize the relationship between them even more than the current situation. This is because they are not optimized, and when the ultrasonic intensity for the substrate 9 to be cleaned is relatively higher than those, damage to the substrate 9 to be cleaned, and conversely if it is weak, uneven cleaning or poor cleaning is caused, Then, as the substrate size of the substrate to be cleaned 9 becomes larger, the influence thereof is more strongly influenced.

Problems caused by the fact that the relationship between the filtration flow rate, the rocking speed, the substrate pitch of the substrate 9 to be cleaned, the type of the cleaning liquid 8 and the ultrasonic intensity received by the surface of the substrate 9 to be cleaned is not optimized. That is, when the filtration flow rate is relatively small with respect to the ultrasonic intensity, the ultrasonic waves can dissociate the fine particles and the like from the substrate surface of the substrate 9 to be cleaned at one time. Since the discharging speed of the ultrasonic cleaning tank 12 to the outside is slow, the possibility that fine particles or the like will re-adhere to the substrate surface increases.
Poor cleaning is likely to occur. On the contrary, if the filtration flow rate is relatively large with respect to the ultrasonic intensity, the propagation of the ultrasonic waves to the substrate surface is hindered and the cleaning effect by the ultrasonic waves becomes difficult to obtain,
Fine particles and the like attached to the surface of the substrate are less likely to be dissociated, and uneven cleaning is likely to occur.

When the rocking speed is relatively slow with respect to the ultrasonic wave intensity, the ultrasonic wave intensity received by the substrate surface per unit area and unit time increases. The chances of damaging the On the other hand, when the rocking speed is relatively high with respect to the ultrasonic wave intensity, the cleaning liquid 8 is agitated more than necessary, so that the propagation of the ultrasonic waves to the substrate surface is hindered and the cleaning effect by the ultrasonic waves is increased. It becomes difficult to obtain the particles, which makes it difficult for the fine particles and the like adhering to the substrate surface to dissociate, and uneven cleaning is likely to occur.

When the substrate pitch of the substrate 9 to be cleaned is relatively small with respect to the ultrasonic wave intensity, the degree of attenuation of the ultrasonic wave intensity increases, so that the ultrasonic wave intensity received by the substrate surface decreases and the substrate surface The propagation of ultrasonic waves to the substrate is hindered, and it becomes difficult to obtain the cleaning effect by the ultrasonic waves. This makes it difficult for the fine particles and the like adhering to the substrate surface to dissociate, and uneven cleaning is likely to occur.

In the case of the cleaning liquid 8 in which the erosion effect is easily generated by the ultrasonic waves, if the ultrasonic wave intensity is relatively large, the substrate to be cleaned 9 is damaged by the erosion effect.

Therefore, conventionally, an ultrasonic intensity sensor is used to detect the ultrasonic intensity of the cleaning liquid 8 in the ultrasonic cleaning tank 12, and based on this, the filtration flow rate, the rocking speed, and the substrate to be cleaned 9 are detected. The pump output of the pump 16 and the motor output for rocking the rocking basket 12 so that the relationship between the substrate pitch, the type of the cleaning liquid 8 and the like and the ultrasonic intensity received by the surface of the substrate 9 to be cleaned is optimized. By changing the substrate pitch or the like of the substrate 9 to be cleaned, damage to the substrate 9 to be cleaned, poor cleaning, uneven cleaning, etc. are avoided.

The ultrasonic intensity sensor 21 used conventionally
5 is used by immersing it in the cleaning liquid 8 inside the ultrasonic cleaning tank 12 as needed. As shown in FIG. 5, it is a rod-shaped type and is composed of a piezoelectric element on the tip side inside the protective tube 22. The ultrasonic wave intensity detecting element 24 for converting the vibration of the cleaning liquid 8 into the electric signal intensity corresponding to the vibration intensity is provided, and the two electrode portions 23 holding the ultrasonic wave intensity detecting element 24 are sandwiched therebetween. .23 and electrode wire 2 connected to them
The electric signal converted by the ultrasonic intensity detecting element 24 is guided to the cable 7 connected to the rear end side of the protective tube 22 by 3a and 23a, and the electric signal is transmitted via the cable 7 to the cable 7 shown in FIG. The electric signal processing device 18 and the data processing device 19 shown in FIG.

[0012]

However, in the ultrasonic intensity detection using the conventional ultrasonic intensity sensor 21, the filtration flow rate, the rocking speed, the substrate pitch of the substrate 9 to be cleaned, and the cleaning liquid 8 are detected. There is a problem that the relationship between the type and the like and the ultrasonic intensity received by the surface of the substrate 9 to be cleaned cannot be effectively optimized.

That is, the conventional ultrasonic intensity sensor 21 is put into the ultrasonic cleaning tank 12 from the outside as necessary and immersed in the cleaning liquid 8 to obtain the ultrasonic intensity of the cleaning liquid 8 inside the ultrasonic cleaning tank 12. Is detected, and the ultrasonic intensity received by the cleaning liquid 8 between the substrates and the peripheral portion of the substrate 9 to be cleaned is detected. Therefore,
The ultrasonic wave intensity directly received by the substrate surface of the substrate to be cleaned 9 cannot be detected, and only a value close to it can be detected. Moreover, in particular, in the case of ultrasonic cleaning treatment of a large substrate such as a glass substrate for a liquid crystal display element, an in-plane distribution of ultrasonic intensity received by the substrate surface is likely to occur due to attenuation due to the distance from the ultrasonic transducer. However, if the conventional ultrasonic intensity sensor 21 wants to detect such an in-plane distribution of the ultrasonic intensity, the ultrasonic intensity must be detected while moving the ultrasonic intensity sensor 21, It takes a lot of time and effort. In addition, when the substrate pitch of the substrate 9 to be cleaned housed in the carrier 11 is narrower than the outer dimensions of the ultrasonic intensity sensor 21, the ultrasonic intensity sensor 21 cannot be inserted between the substrates, so that the ultrasonic force between the substrates is not increased. The sound wave intensity cannot be detected, and only the ultrasonic wave intensity around the substrate can be detected.

Therefore, as described above, in the detection of the ultrasonic intensity using the conventional ultrasonic intensity sensor 21, the filtering flow rate, the rocking speed, the substrate pitch, the type of the cleaning liquid, and the ultrasonic intensity received by the substrate surface. It has been difficult to optimize the relationship with.

Therefore, the present invention has been made in view of the above problems, and provides an ultrasonic intensity sensor capable of detecting the ultrasonic intensity directly received by the substrate surface of the substrate to be cleaned at a plurality of points, and the ultrasonic intensity sensor In order to efficiently remove fine particles and the like adhering to the surface of the substrate to be cleaned using the intensity sensor, the filtration flow rate, the rocking speed, the substrate pitch, the type of cleaning liquid, and the ultrasonic intensity received by the substrate surface are used. It is an object of the present invention to propose a detection method that can effectively detect the ultrasonic intensity of the substrate surface of the substrate to be cleaned, which is necessary for optimizing the relationship.

[0016]

In order to solve the above-mentioned problems, the ultrasonic intensity sensor according to claim 1 of the present invention is characterized in that a plurality of ultrasonic intensity detecting elements are formed on the surface of the substrate. I am trying.

In order to solve the above-mentioned problems, the ultrasonic intensity sensor according to a second aspect of the present invention is characterized in that, in the ultrasonic intensity sensor according to the first aspect, the ultrasonic intensity detecting element is a piezoelectric element. There is.

In order to solve the above-mentioned problems, the ultrasonic intensity sensor according to claim 3 of the present invention is the ultrasonic intensity sensor according to claim 1 or 2, wherein a plurality of ultrasonic intensity detection elements are provided. It is characterized in that a protective film is formed.

In order to solve the above-mentioned problems, an ultrasonic intensity detecting method according to a fourth aspect of the present invention arranges a plurality of the ultrasonic intensity sensors according to the above-mentioned first, second or third, and determines the ultrasonic intensity. It is characterized by three-dimensional detection.

In order to solve the above-mentioned problems, the ultrasonic intensity detecting method according to claim 5 of the present invention is the ultrasonic intensity detecting method according to claim 4, wherein the holding member for holding the substrate to be cleaned is provided inside. It is characterized by arranging a plurality of ultrasonic intensity sensors.

[0021]

According to the above-mentioned structure, since the ultrasonic wave intensity detecting element is formed on the substrate surface, the ultrasonic wave intensity directly received by the substrate surface can be detected, and more than one ultrasonic wave intensity detecting element is provided. Since the individual pieces are provided, it becomes possible to detect the ultrasonic wave intensity at a plurality of locations such as the central portion and the peripheral portion on the substrate surface. And if the configuration of claim 2 is adopted,
A piezoelectric element can be used as the ultrasonic intensity detecting element, and the ultrasonic intensity detecting element can be superposed by providing the protective film on the ultrasonic intensity detecting element. It is possible to effectively suppress the peeling by the sound wave and extend the life of the ultrasonic intensity sensor.

Then, such an ultrasonic intensity sensor is
As described in claim 4, by arranging a plurality of sheets, the ultrasonic intensity can be three-dimensionally detected,
For example, as an arrangement method thereof, as described in claim 5, by installing a plurality of substrates inside the holding member for holding the substrate to be cleaned, the ultrasonic intensity received by the substrate to be cleaned held by the holding member is increased. Can be detected three-dimensionally. More specifically, by replacing some or all of the substrates to be cleaned held by the holding member with the ultrasonic intensity sensors, ultrasonic waves received by the substrate surface of each substrate to be cleaned held by the holding member can be received. The intensity can be detected.

Therefore, by using such an ultrasonic intensity sensor to detect ultrasonic intensity three-dimensionally,
For example, in an ultrasonic cleaning device, the filtration flow rate, the rocking speed,
It is possible to effectively optimize the relationship between the substrate pitch, the type of cleaning liquid, and the ultrasonic wave intensity received on the substrate surface, and to prevent damage to the substrate to be cleaned, poor cleaning of the substrate to be cleaned, uneven cleaning, etc. It is possible to efficiently remove the fine particles and the like adhering to the substrate to be cleaned without causing a problem.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

An ultrasonic cleaning apparatus to which the ultrasonic intensity sensor 1 according to the present invention is applied is an apparatus used for cleaning semiconductor devices, and as shown in FIG. 3, an ultrasonic cleaning tank 12 for storing a cleaning liquid 8 therein. Is provided, and an ultrasonic transducer 14 for generating ultrasonic waves is provided at the bottom of the ultrasonic cleaning tank 12.
Is provided. In addition, inside the ultrasonic cleaning tank 12,
An oscillating car 13 that is oscillated by the motor output of a motor (not shown) is provided, and the cleaning liquid 8 is agitated by oscillating the oscillating car 13. An overflow tank 12a is provided above the ultrasonic cleaning tank 12, and the overflow tank 12a is provided.
By connecting the bottom portion of a and the ultrasonic cleaning tank 12 via the communication pipe 15 provided with the pump 16 and the filter 17, the cleaning liquid 8 in the ultrasonic cleaning tank 12 flows from the lower side to the upper side. Overflow system is configured. In this over-flow system, the fine particles and the like in the cleaning liquid are efficiently captured and filtered by the filter 17 in consideration of the particle diameter of the fine particles and discharged from the cleaning liquid. Then, the cleaning liquid 8 after filtering is returned to the ultrasonic cleaning tank 12 again and is circulated and used.

When the substrate 9 to be cleaned, which is a semiconductor device, is cleaned using such an ultrasonic cleaning apparatus, a plurality of substrates 9 to be cleaned are mounted on a carrier 11 which is a holding member for holding the substrate to be cleaned. In a state where the ultrasonic cleaning tank 12 is housed at a predetermined interval, the ultrasonic cleaning tank 12 is placed in an oscillating cage 13. When the carrier 11 is put into the ultrasonic cleaning tank 12, the ultrasonic vibrator 14 is activated and ultrasonic waves are emitted, and at the same time, the swing of the swing cage 13 is started. The ultrasonic wave generated by the ultrasonic oscillator 14 first propagates to the cleaning liquid 8 and then to the substrate 9 to be cleaned through the vibrated cleaning liquid 8. When the generated frequency is several tens of kHz or less, the erosion effect is mainly generated. Further, in the megasonic region, fine particles and the like adhering to the surface of the substrate 9 to be cleaned are dissociated due to the vibration acceleration effect. The dissociated fine particles and the like are discharged to the outside of the ultrasonic cleaning tank 12 by the overflow system of the ultrasonic cleaning tank 12, and are efficiently captured / filtered by the filter 17 and removed. The filtered clean cleaning liquid 8 is returned to the inside of the ultrasonic cleaning tank 12 again.

The ultrasonic intensity sensor 1 according to the present invention provided in such an ultrasonic cleaning apparatus is, as shown in FIG.
The base substrate 2 has the same size as the substrate 9 to be cleaned, and the ultrasonic intensity for electrically converting a plurality of ultrasonic intensities so as to fill almost the entire area of the substrate surface of the base substrate 2. Piezoelectric elements 3 that are detection elements are arranged and formed. In reality, the piezoelectric element 3 is not directly formed on the surface of the base substrate 2, but the electrode 4 is formed on the surface of the base substrate 2 as shown in the sectional view of FIG. The piezoelectric element 3 is formed on the upper side, and the other electrode 4 is further formed thereon. Electrode wire portions 4a, 4a for guiding an electric signal detected by the piezoelectric element 3 to an adapter 6 provided at one end of the base substrate 2 are integrally formed with the pair of electrodes 4, 4. . A cable 7 is connected to an adapter 6 provided at one end of the base substrate 2, and an electric signal processing device 18, a data processing device 19, and a monitor 20 shown in FIG. It is connected.

.., electrode wire portions 4a, 4
, and the piezoelectric elements 3 are formed on the surface of the base substrate 2 by the sputtering method or the like for the electrodes 4, 4, the electrode wire portions 4a, 4a ,. By forming a thin film with a desired film thickness, and then performing fine processing such as etching and patterning to a desired size. In this embodiment, a protective film 5 is further formed on the thin film. By covering it, the piezoelectric element 3 ...
, And the electrode wire portions 4a, 4a, ... Are prevented from being peeled off, and a treatment is performed to extend the life of the ultrasonic intensity sensor 1.

As shown in FIG. 3, when the ultrasonic intensity sensor 1 is installed inside the ultrasonic cleaning tank 12 of the ultrasonic cleaning device while being held in the carrier 11, for example, the ultrasonic vibrator 14 is installed. The ultrasonic waves generated by the ultrasonic wave propagate through the cleaning liquid 8 to generate vibration of the cleaning liquid 8. The vibration of the cleaning liquid 8 is converted into an electric signal corresponding to the vibration intensity by the individual piezoelectric elements 3 ... Formed on the base substrate 2 in the ultrasonic intensity sensor 1. The electric signal is guided to the adapter 6 at the end of the base substrate 2 by the electrodes 4 and 4 formed on both surfaces of the piezoelectric element 3 and the electrode wire portions 4a and 4a, and the cable connected to the adapter 6. It is transmitted to the electric signal processing device 18 via 7. The electric signal output from the electric signal processing device 18 is the data processing device 19
The ultrasonic intensity detected by each piezoelectric element 3 on the substrate surface of the base substrate 2 after being input to and processed is displayed on the monitor 20 as an electric signal intensity, and the ultrasonic intensity is detected and measured. As a result, in the same state as the ultrasonic intensity sensor 1, the ultrasonic intensity received by the substrate 9 to be cleaned placed inside the ultrasonic cleaning tank 12 can be detected and measured two-dimensionally (two-dimensionally). .

Further, a plurality of such ultrasonic intensity sensors 1 are prepared and replaced with several substrates 9 to be cleaned held in the carrier 11, or all the substrates 9 to be cleaned held. The ultrasonic intensity received by each substrate surface of the plurality of substrates 9 to be cleaned held in the carrier 11 is set by replacing the above with the ultrasonic cleaning tank 12 of the ultrasonic cleaning device. Spatial (3
It can be detected and measured (dimensionally).

Therefore, the pump 16 for controlling the filtration flow rate based on each ultrasonic intensity detected in this way.
The pump output and the motor output of the rocking cage 13 for controlling the rocking speed can be adjusted to optimize the filtration flow rate and rocking speed at the substrate pitch. Further, when the board pitch is changed, these relationships also change. However, as described above, the ultrasonic wave intensity sensors 1 ... Are arranged again at the board pitch, and the ultrasonic wave intensity is detected to change the board pitch. Later, these relationships can be easily optimized.

As a result, even if the size of the substrate 9 to be cleaned is further increased, by using the ultrasonic intensity sensor 1 according to the present invention, the filtration flow rate, the rocking speed, the substrate pitch, and the cleaning liquid 8 can be obtained. It is possible to effectively optimize the relationship between the type of the substrate 9 and the ultrasonic intensity received by the substrate surface of the substrate 9 to be cleaned, damage to the substrate 9 to be cleaned, poor cleaning of the substrate 9 to be cleaned, uneven cleaning, etc. The fine particles and the like adhering to the substrate 9 to be cleaned can be efficiently removed without causing the above problem.

In this embodiment, the piezoelectric element 3 is exemplified as the ultrasonic wave intensity detecting element, but it is not limited to this as long as it can detect the ultrasonic wave intensity. Similarly, the array state of the piezoelectric elements 3 formed on the surface of the base substrate 2 is not limited to this, as long as the ultrasonic intensity received on the substrate surface of the base substrate 2 can be entirely detected. .

[0034]

As described above, the present invention constitutes an ultrasonic wave intensity sensor in which a plurality of ultrasonic wave intensity detecting elements are formed on the surface of a substrate, and the ultrasonic wave intensity sensor is used for holding a substrate to be cleaned. The ultrasonic intensity received directly by the substrate surface of the substrate to be cleaned held inside the holding member is three-dimensionally detected by arranging a plurality of sheets inside the holding member.

Therefore, by using such an ultrasonic intensity sensor, for example, in the ultrasonic cleaning apparatus, the filtration flow rate, the rocking speed, the substrate pitch, the type of the cleaning liquid, the ultrasonic intensity received by the substrate surface, and the like. It is possible to effectively optimize the relationship between the substrate to be cleaned, and the fine particles etc. that adhere efficiently to the substrate to be cleaned without causing damage to the substrate to be cleaned and defects such as defective cleaning and uneven cleaning of the substrate to be cleaned. There is an effect that can be removed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a plan view of an ultrasonic intensity sensor without a protective film.

FIG. 2 is a sectional view of a main part of the ultrasonic intensity sensor.

FIG. 3 is a schematic view of an ultrasonic cleaning device in a state where the ultrasonic intensity sensor is used.

FIG. 4 is a schematic view of an ultrasonic cleaning device in a state where a conventional ultrasonic intensity sensor is used.

FIG. 5 is a schematic sectional view of a conventional ultrasonic intensity sensor.

[Explanation of symbols]

 1 Ultrasonic Strength Sensor 2 Base Substrate (Substrate) 3 Piezoelectric Element (Ultrasonic Strength Detection Element) 4 Electrode 4a Electrode Wire Part 5 Protective Film 6 Adapter 7 Cable 8 Cleaning Liquid 9 Cleaning Substrate 11 Carrier (Holding to Hold Cleaning Substrate) Member) 12 Ultrasonic cleaning tank 13 Oscillating basket 14 Ultrasonic transducer 18 Electric signal processing device 19 Data processing device 20 Monitor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04R 17/02 7103-5H

Claims (5)

[Claims] 1. An ultrasonic intensity sensor, wherein a plurality of ultrasonic intensity detecting elements are formed on a surface of a substrate. 2. The ultrasonic intensity sensor according to claim 1, wherein the ultrasonic intensity detecting element is a piezoelectric element. 3. The protective film is formed on a plurality of ultrasonic intensity detecting elements, as described above.
The ultrasonic intensity sensor described. 4. An ultrasonic intensity detecting method, comprising arranging a plurality of ultrasonic intensity sensors according to claim 1, 2 or 3 and detecting ultrasonic intensity three-dimensionally. 5. The ultrasonic intensity detecting method according to claim 4, wherein a plurality of ultrasonic intensity sensors are arranged inside the holding member for holding the substrate to be cleaned.