JP7750677B2 - Cleaning equipment - Google Patents

Description

The present invention relates to a cleaning device.

In the manufacturing process of semiconductor devices, it is sometimes necessary to clean the surface of the semiconductor wafer, which serves as the substrate, with a high degree of cleanliness. For example, after chemical mechanical polishing (CMP) is performed to flatten the surface of the substrate, particles such as polishing debris containing organic matter and metals, and slurry residue (hereinafter referred to as contaminants) adhere to the surface of the substrate.

Contaminants can interfere with even film formation and lead to short circuits in circuit patterns, resulting in product defects. Therefore, they must be removed by cleaning the substrate with a cleaning liquid. A known cleaning device for this type of cleaning is one that uses a rotating brush. This cleaning device rotates the substrate and moves the rotating brush in a direction parallel to the substrate, bringing it into contact with the substrate's surface via the cleaning liquid. This causes contaminants adhering to the substrate's surface to float in the cleaning liquid and be expelled from the substrate by the brush, thereby cleaning the entire substrate.

Specifically, the peripheral edge of the substrate is held by a grooved or stepped roller, which is then rotated. Meanwhile, the cleaning brush is attached to the tip of a swinging arm, and the swinging arm is swung to move the cleaning brush in an arc. The cleaning liquid is sprayed from the nozzle from the outside of the substrate toward the center of the substrate, that is, toward the middle of the brush's movement path.

In the past, polyamide resins such as PVA were used as brush materials, but in recent years, fluororesins such as PTFE and PFA have become more commonly used (see Patent Document 1). One advantage of fluororesins is their corrosion resistance to cleaning solutions. Cleaning solutions can be alkaline, such as APM (ammonia water + hydrogen peroxide + water), or acidic, such as hydrofluoric acid, and fluororesins have excellent corrosion resistance to all types of cleaning solutions.

Japanese Patent Application Publication No. 10-41260

When the cleaning solution is alkaline, contaminants adhering to the surface of the substrate become negatively charged. At this time, the surface of the substrate also becomes negatively charged, causing contaminants (e.g., organic contaminants and metal contaminants) to repel and float away from the substrate due to Coulomb force. Meanwhile, the fluororesin brushes used to clean substrates are known to easily become negatively charged even when stationary, but they become even more negatively charged due to air friction during rotation and contact friction with the cleaning solution. Therefore, the surface of the substrate where the fluororesin brush passes becomes positively charged due to electrostatic induction. In this way, the substrate, which was originally negatively charged, becomes positively charged, attracting negatively charged contaminants and making their removal difficult.

Furthermore, when the cleaning solution is, for example, APM, the formation of an oxide film by the hydrogen peroxide solution and the etching of the oxide film by the ammonia simultaneously occur on the surface of the substrate. Taking the case where the substrate is a silicon wafer as an example, the reaction is as follows:

This oxide film would normally form between the substrate surface and the contaminants, and when etched, would lift the contaminants from the substrate surface. However, if the contaminants remain adsorbed to the substrate surface due to the electrostatic induction described above, the oxide film not only fails to lift the contaminants from the substrate surface, but also accumulates around the contaminants, burying them. This makes it even more difficult to remove the contaminants with a brush.

The present invention aims to provide a cleaning device that prevents contaminants from adsorbing onto the surface of a substrate.

The cleaning device of the present invention comprises a rotation drive unit that drives a substrate to rotate, a cleaning head that brings a rotating fluororesin brush into contact with the surface of the rotating substrate to clean the surface of the substrate, a brush drive unit that moves the cleaning head in a direction parallel to the surface of the substrate, a cleaning liquid discharge unit that discharges an alkaline cleaning liquid from a discharge port onto the substrate, and a static elimination unit that discharges the cleaning liquid onto the substrate by the cleaning liquid discharge unit and sets the potential of the brush to 0 V while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate by the brush drive unit.
The cleaning device of the present invention also includes a rotation drive unit that drives a substrate to rotate, a cleaning head that brings a rotating fluororesin brush into contact with the surface of the rotating substrate to clean the surface of the substrate, a brush drive unit that moves the cleaning head in a direction parallel to the surface of the substrate, a cleaning liquid discharge unit that discharges an alkaline cleaning liquid from a discharge port onto the substrate, and a charge removal unit that discharges the cleaning liquid onto the substrate by the cleaning liquid discharge unit and makes the potential of the brush equal to or higher than 0 V while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate by the brush drive unit, and the charge removal unit is an electrode that is provided inside a brush holder that holds the brush, is negatively charged by application of a voltage, and makes the potential of the brush equal to or higher than 0 V by electrostatic induction.
The cleaning apparatus of the present invention also includes a rotation drive unit that drives a substrate to rotate, a cleaning head that brings a rotating fluororesin brush into contact with the surface of the rotating substrate to clean the surface of the substrate, a brush drive unit that moves the cleaning head in a direction parallel to the surface of the substrate, a cleaning liquid discharge unit that discharges an alkaline cleaning liquid onto the substrate from a discharge port, and a static elimination unit that discharges the cleaning liquid onto the substrate by the cleaning liquid discharge unit and keeps the potential of the brush at 0 V or higher while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate by the brush drive unit, wherein the static elimination unit is an ionizer that emits positive ions to the brush, and further includes a surface potential sensor that detects the potential of the brush or the substrate, and a charge amount control unit that adjusts the output of the ionizer based on the potential of the brush or the potential of the substrate.

The cleaning device of the present invention can prevent contaminants from adsorbing onto the surface of the substrate.

FIG. 1 is a perspective view showing a schematic configuration of a cleaning device according to an embodiment. 1A is a side view showing the roller in the release position and FIG. 1B is a side view showing the roller in the holding position. 1A is a plan view showing the roller in the release position, and FIG. 1B is a plan view showing the roller in the holding position. FIG. FIG. 1A is a bottom view showing an example in which a single brush is arranged, and FIG. 1B is a bottom view showing an example in which multiple brushes are arranged. 1A is a plan view showing a cleaning head at the start position of cleaning, FIG. 1B is a plan view showing a cleaning head during cleaning, and FIG. 1C is a plan view showing a cleaning head at the end position. FIG. 10 is a side view showing a modified example of the cleaning head. FIG. 10 is a side view showing a modified example of the cleaning head.

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIG. 1, this embodiment is a cleaning apparatus 1 that cleans a substrate W using a cleaning liquid and a brush while rotating the substrate W using rollers. The substrate W is typically a semiconductor wafer, but may also be a substrate for a display device, etc. If the substrate for a display device is rectangular, it is preferable to rotate it using a spin table instead of rollers.

As shown in FIG. 1, the cleaning device 1 includes a rotation drive unit 10, a cleaning head 20, a brush drive unit 30, a cleaning liquid discharge unit 40, and a control unit 90 that controls the operation of these components.

The rotation drive unit 10 rotates the substrate W. The rotation drive unit 10 has a first holder 11, a second holder 12, a first drive unit 13, and a second drive unit 14.

The first holding unit 11 and the second holding unit 12 are arranged at opposing positions across the substrate W. Each of the first holding unit 11 and the second holding unit 12 has a pair of rollers 10a. The rollers 10a are rotatable around an axis perpendicular to the substrate W. The rollers 10a have a large diameter portion and a small diameter portion provided on the upper surface of the large diameter portion. The side surfaces of the large diameter portion and the small diameter portion are tapered so that the boundary where they meet reduces in diameter. The first holding unit 11 and the second holding unit 12 hold the substrate W by abutting the boundary between the large diameter portion and the small diameter portion of each roller 10a against the peripheral edge of the substrate W.

The first drive unit 13 supports the first holder 11, rotates the rollers 10a of the first holder 11, and moves the first holder 11 in a direction toward and away from the substrate W using a drive mechanism not shown. The second drive unit 14 supports the second holder 12, rotates the rollers 10a of the second holder 12, and moves the second holder 12 in a direction toward and away from the substrate W using a drive mechanism not shown.

The first drive unit 13 and the second drive unit 14 are provided with a rotation mechanism (not shown) that drives the rollers 10a. The rotation mechanism is, for example, a belt drive mechanism. That is, the rotation mechanism is configured so that a belt is stretched between a pulley attached to the drive shaft of a motor (drive source) and a pulley attached to the drive shaft of one of the rollers 10a, and between pulleys attached to each drive shaft of the pair of rollers 10a, and the pair of rollers 10a can be rotated via these belts. However, the rotation mechanism is not limited to this, and may be configured, for example, so that each roller 10a is rotated by a motor (drive source) attached to the drive shaft of each roller 10a.

The drive mechanism has rotary cylinders that move drive shafts, respectively provided at the lower ends of the first drive unit 13 and the second drive unit 14, in directions parallel to the surface of the substrate W, away from each other. When the drive mechanism moves the first holding unit 11 and the second holding unit 12 away from each other, they reach a release position where the rollers 10a are released from the substrate W, as shown in Figures 2(A) and 3(A). At this time, the substrate W is supported by the large diameter portions of the rollers 10a. When the drive mechanism moves the first holding unit 11 and the second holding unit 12 toward each other, they reach a holding position where the rollers 10a abut against and hold the substrate W, as shown in Figures 2(B) and 3(B).

The cleaning head 20 cleans the surface of the substrate W by bringing the rotating brush 25 into contact with the surface of the rotating substrate W. Note that contact here includes both direct contact by the brush 25 and contact via a cleaning liquid. As shown in Figures 2(A) and (B), a pair of cleaning heads 20 are provided with the substrate W sandwiched between them, and are capable of cleaning both sides of the substrate W. As shown in Figures 4 and 5, each cleaning head 20 has a body 21, a motor 22, a brush holder 23, a support 24, a brush 25, an electrode 26, and a surface potential sensor 27.

The body 21 is a cylindrical container that houses the motor 22. The motor 22 is the drive source that rotates the brush 25. The brush holder 23 is a cylindrical container that is attached to the drive shaft of the motor 22 and to which the support 24 is detachably attached. The brush holder 23 is rotatable independently of the body 21. The support 24 is a disc-shaped member that is detachably attached to the brush holder 23 by a chuck mechanism or the like and supports the brush 25.

As shown in Figures 6(A) and (B), the brush 25 is a cylindrical member made of a flexible and elastic material. In this embodiment, the brush 25 is made of a spongy fluororesin. Examples of fluororesin include PTFE and PFA. A fluororesin bristle brush may also be used. In other words, the brush 25 in this embodiment may be a sponge-like mass, a mass of numerous densely packed hairs, or a sponge-like mass of numerous fibers. The number of brushes 25 provided on the support 24 may be one, as shown in Figure 6(A), or multiple, as shown in Figure 6(B). In Figure 6(B), multiple brushes 25 (e.g., six brushes) are arranged around the center of the support 24.

The electrode 26 is a static eliminator that neutralizes the brush 25. The electrode 26 is a conductive member such as a metal, and is provided inside the brush holder 23. Specifically, it is provided on the side opposite the side supporting the brush 25, as viewed from the support 24. The electrode 26 is connected to a DC power supply (not shown), and can be negatively charged by applying a voltage from the DC power supply. The negatively charged electrode 26 neutralizes the brush 25 through electrostatic induction, i.e., raises the potential of the brush 25 to 0V or above. Note that the electrode 26 may be charged using an AC power supply instead of a DC power supply.

The surface potential sensor 27 is positioned a predetermined distance to the side of the brush 25 via a fixture 271 provided on the side of the body 21. The surface potential sensor 27 detects the electric field generated by the charge on the brush 25 and detects the potential of the brush 25 based on the strength of the detected electric field and the distance to the brush 25. The distance to the brush 25 may be adjusted using the fixture 271. In this case, a photoelectric sensor (not shown) can be used in combination to measure the distance to the brush 25 and detect the potential of the brush 25. The surface potential sensor 27 feeds back the detected potential of the brush 25 to the charge amount control unit 92, described below.

The brush driving unit 30 moves the cleaning head 20 in directions parallel and perpendicular to the surface of the substrate W. As shown in Figures 2(A) and (B), a pair of brush driving units 30 are provided, one for each cleaning head 20. As shown in Figure 1, each brush driving unit 30 has an arm 31 and a driving mechanism 32.

The arm 31 is a member that extends in a direction parallel to the surface of the substrate W, and has the cleaning head 20 attached to one end. That is, when cleaning the substrate W, the pair of arms 31 are positioned in positions facing both surfaces of the substrate W. When cleaning the substrate W is not being performed, the arms 31 are positioned in a standby position (not shown) outside the substrate W.

The drive mechanism 32 has a swing mechanism and an elevation mechanism that move the arm 31.

As shown in Figures 7(A) to 7(C), the swing mechanism reciprocates the arm 31 in a direction parallel to the substrate W, from the outer periphery of the substrate W to the outer periphery on the opposite side, along an arc trajectory with the end opposite the cleaning head 20 as its axis. The swing mechanism also reciprocates the arm 31 from a standby position to the outer periphery of the substrate W. The swing mechanism has a support shaft extending from the arm 31 in a direction perpendicular to the surface of the substrate W, and a motor (not shown) that serves as a drive source for swinging the support shaft.

As shown in Figures 2(A) and (B), the lifting mechanism moves the arms 31 in a direction in which the cleaning head 20 approaches or moves away from the surface of the substrate W. That is, the pair of arms 31 move toward each other, sandwiching both surfaces of the substrate W, and then move away from each other. That is, the position where the pair of arms 31 sandwich both surfaces of the substrate W is the starting point for the oscillation of the brushes 25, as shown in Figure 7(A), and the position where the pair of arms 31 separate from both surfaces of the substrate W is the end point for the oscillation of the brushes 25, as shown in Figure 7(C). The lifting mechanism can employ a ball screw mechanism, cylinder, or the like that raises and lowers the support shaft of the arm 31.

The cleaning liquid discharge unit 40 discharges cleaning liquid from the discharge port 41a toward both surfaces of the rotating substrate W (see Figures 7(A) to 7(C)). The cleaning liquid in this embodiment is alkaline, such as APM (ammonia water + hydrogen peroxide + water). The cleaning liquid discharge unit 40 has a nozzle 41.

The nozzles 41 are a pair of tubes arranged on either side of the substrate W. One end of the nozzle 41 is bent, for example, at a 45° angle with respect to the surface of the substrate W, and has an outlet 41a that discharges cleaning liquid toward the surface of the substrate W. The other end of the nozzle 41 is connected to a cleaning liquid supply device (not shown). The supply device has, for example, a liquid delivery device connected to an APM supply device, a valve, etc., and supplies APM. Note that one nozzle 41 may be provided for each surface of the substrate W, or multiple nozzles 41 may be provided for each surface. Furthermore, the number of nozzles provided for one surface of the substrate W may be different from the number provided for the other surface.

The control unit 90 controls the rotation drive unit 10, the cleaning head 20, the brush drive unit 30, and the cleaning liquid discharge unit 40. As shown in FIG. 5, the control unit 90 has a mechanism control unit 91 and a charge amount control unit 92.

The mechanism control unit 91 controls the operation of the first drive unit 13 and second drive unit 14 of the rotation drive unit 10, the rotation of the motor 22 of the cleaning head 20, the operation of the drive mechanism 32 of the brush drive unit 30, and the ejection of cleaning liquid from the nozzle 41 of the cleaning liquid ejection unit 40.

The charge amount control unit 92 monitors the potential of the brush 25 detected by the surface potential sensor 27 and adjusts the voltage applied to the electrode 26 so that the potential of the brush 25 is maintained within a predetermined range, i.e., a range above 0 V.

(operation)
The operation of the cleaning apparatus 1 configured as described above will be described. First, in the pre-processing step, ozone water is applied to the surface of the processed substrate W, forming an oxide film and making the surface hydrophilic. Organic contaminants (such as slurry) and metal contaminants remaining from the CMP step (the step before this step) remain on the surface of the substrate W on which this oxide film is formed. This means that the ozone water is supplied to both sides of the substrate W with the contaminants still attached, i.e., the oxide film is formed with the contaminants still attached. Although ozone water has the ability to remove organic matter, the pre-processing step is not intended to remove organic matter, but rather to hydrophilize the front and back surfaces of the substrate W. The substrate W unloaded from the pre-processing step is loaded between the rollers 10a of the first and second holders 11 and 12 of the cleaning apparatus 1, as shown in FIGS. 2A and 3A. The substrate W is loaded while both sides are wet with the ozone water supplied in the pre-processing step.

As shown in FIG. 2(B), the first holding unit 11 and the second holding unit 12 move toward each other, and the four rollers 10a come into contact with the periphery of the substrate W, thereby holding the substrate W. The rollers 10a rotate while holding the substrate W, causing the substrate W to rotate. The substrate W rotates at a low speed of, for example, 20 to 60 rpm.

The pair of arms 31 are initially in a standby state at a standby position outside the substrate W. In this state, the motor 22 rotates the brush 25. At this time, the fluororesin brush 25, which tends to be negatively charged even when stationary, becomes even more negatively charged due to air friction. Next, in the cleaning head 20, a voltage is applied from the power supply to the electrode 26, causing the electrode 26 to become negatively charged. The negatively charged electrode 26 raises the potential of the brush 25 to 0 V or above, i.e., 0 V or positive, due to electrostatic induction. Note that a potential of 0 V on the brush 25 means that the brush 25 has been neutralized and the electric charge has been neutralized. A positive potential on the brush 25 means that the brush 25 is positively charged.

The pair of arms 31 then swing over the outer periphery of the substrate W as shown in FIG. 7(A) and stop temporarily. Then, as the pair of arms 31 move toward each other toward the substrate W, the rotating brushes 25 of the pair of cleaning heads 20 come into contact with both sides of the substrate W and sandwich the substrate W, as shown in FIG. 2(B). At the same time, the outlets 41a of the nozzles 41 eject alkaline cleaning liquid onto the surface of the substrate W. The cleaning liquid covers the surface of the substrate W and negatively charges contaminants adhering to the substrate W. The black arrow indicates the direction of rotation of the substrate W.

At this time, the brush 25 becomes even more negatively charged due to its inherent tendency to become negatively charged, the air friction caused by the rotation mentioned above, and contact friction with the cleaning solution. However, the voltage applied to the electrode 26 keeps the potential of the brush 25 above 0V. Furthermore, by monitoring the charged state of the brush 25 via the surface potential sensor 27, the voltage applied to the electrode 26 can be adjusted to maintain the potential of the brush 25 above 0V.

The potential of the brush 25 is preferably close to 0 V. If the brush 25 is highly positively charged, the surface of the substrate W that the brush 25 contacts will become negatively charged due to electrostatic induction. As a result, negatively charged contaminants repel the negatively charged substrate W due to electrostatic induction and tend to float away from the substrate W. On the other hand, negatively charged contaminants are more likely to be attracted to the positively charged brush 25 due to electrostatic attraction. In other words, in conventional technology, contaminants are electrostatically attracted to a positively charged substrate, but contaminants are less likely to adhere to the brush, resulting in fewer opportunities to clean the brush. However, in this embodiment, if the brush 25 is excessively positively charged as described above, the brush 25 will be more likely to attract contaminants, which will increase the frequency of cleaning or replacing the brush 25 and reduce cleaning efficiency. In this regard, by maintaining the potential of the brush 25 at near 0V, the surface of the substrate W that the brush 25 comes into contact with is less likely to become charged, and negatively charged contaminants are not attracted to the substrate W, making them more likely to separate from the substrate W, and also preventing them from being attracted to the brush 25.

The pair of arms 31 then swing, causing the pair of brushes 25 to move horizontally. That is, as shown in Figures 7(A) and (B), the brush 25 starts moving from one side of the outer periphery of the substrate W and moves along the arc trajectory indicated by the white arrow in the figure, pushing contaminants along with the cleaning liquid to the outer periphery of the substrate W. At this time, the brush 25 in contact with the substrate W is charged to a potential of 0 V or higher, preventing the surface of the substrate W from becoming positively charged. As a result, negatively charged contaminants are not adsorbed to the surface of the substrate W but tend to float up from the surface of the substrate W and are easily swept away by the brush 25. Note that even if the potential of the brush 25 is 0 V, the surface of the substrate W tends to become negatively charged due to the alkaline cleaning liquid. Furthermore, the voltage applied to the electrode 26 may be adjusted while the brush 25 is moving horizontally.

As shown in Figure 7(C), when the brush 25 moves beyond the other side of the outer periphery of the substrate W and leaves the substrate W, the rotation of the brush 25 and the discharge of cleaning liquid from the discharge port 41a are stopped, thereby ending the cleaning process.

The peripheral speed differs between the outer periphery and the center of the substrate W. The peripheral speed is faster on the outer periphery and the area to be cleaned per rotation is larger, so the horizontal movement of the brush 25 is slowed. That is, the movement speed of the arm 31 by the brush drive unit 30 is slowed. On the other hand, the peripheral speed is slower toward the center and the area to be cleaned per rotation is smaller, so the horizontal movement of the brush 25 is faster. That is, the movement speed of the arm 31 by the brush drive unit 30 is increased. On the other hand, if the cleanliness of the substrate W can be sufficiently maintained without changing the speed of the arm 31, the speed at which the brush 25 is oscillated may be constant to make it easier to control the brush drive unit 30.

The pair of arms 31 then move away from each other, separating the pair of brushes 25, and the arms 31 then swing, retreating to a standby position outside the substrate W. The above operation may then be repeated to perform multiple cleanings with the brushes 25. In this case, the arms 31 return to the position where cleaning starts after each cleaning (see Figures 2(A) and 7(A)).

(Action and effect)
(1) The cleaning apparatus 1 of this embodiment includes a rotation drive unit 10 that rotates the substrate W, a cleaning head 20 that brings a rotating fluororesin brush 25 into contact with the surface of the rotating substrate W to clean the surface of the substrate W, a brush drive unit 30 that moves the cleaning head 20 in a direction parallel to the surface of the substrate W, a cleaning liquid discharge unit 40 that discharges an alkaline cleaning liquid onto the substrate W from a discharge port 41 a, and a charge removal unit that discharges the cleaning liquid onto the substrate W using the cleaning liquid discharge unit 40 and causes the brush 25 to have a potential of 0 V or higher while the brush 25 is moving parallel to the surface of the substrate W while in contact with the surface of the substrate W using the brush drive unit 30. When the brush 25, which is charged to 0 V or higher, comes into contact with the substrate W, the surface of the substrate W is prevented from becoming positively charged. As a result, contaminants that are negatively charged by the alkaline cleaning liquid are less likely to adhere to the surface of the substrate W and are more likely to float off the substrate W, making it easier for the brush 25 to sweep the contaminants off. Furthermore, by preventing the surface of the substrate W from being positively charged, the possibility of contaminants swept away by the brush 25 re-adhering to the surface of the substrate W is reduced, thereby improving the cleanliness of the substrate W. Even if the potential of the brush 25 is 0 V, the surface of the substrate W tends to be negatively charged by the alkaline cleaning liquid, and therefore it is considered that the same effect as when the brush 25 is positively charged is exerted.

Conventionally, when a fluororesin brush, which tends to be negatively charged, comes into contact with the surface of a substrate W, the substrate W becomes positively charged due to electrostatic induction, and negatively charged contaminants are attracted to the brush, resulting in insufficient sweeping. Furthermore, when the substrate W reacts with APM while it has attracted contaminants, an oxide film is deposited, burying the contaminants in the oxide film, making sweeping with the brush even more difficult. In contrast, the neutralization unit of this embodiment sets the potential of the brush 25 to 0V or higher. This prevents the surface of the substrate W that comes into contact with the brush 25 from becoming positively charged, making it difficult for negatively charged contaminants to adhere to the surface of the substrate W and more likely to lift off the substrate W, reducing the risk of them becoming embedded in the oxide film.

(2) The static eliminator in this embodiment is an electrode 26 that is provided inside the brush holder 23 that holds the brush 25. When a voltage is applied, the electrode 26 becomes negatively charged and raises the potential of the brush 25 to 0 V or higher through electrostatic induction. This makes it easy to charge the brush 25 to 0 V or higher. In addition, because the electrode 26 is made of a conductive material such as metal, there is no risk of malfunction. Furthermore, because the electrode 26 in this embodiment is stored inside the brush holder 23, there is no risk of it interfering with other components that make up the cleaning device 1.

(3) The cleaning apparatus 1 of this embodiment further includes a surface potential sensor 27 that detects the potential of the brush 25 and a charge amount control unit 92 that adjusts the voltage applied to the electrode 26 based on the potential of the brush 25. This allows the potential of the brush 25 to be monitored. Even if the brush 25 becomes negatively charged again due to contact friction with the cleaning liquid or the substrate W, the voltage applied to the electrode 26 can be adjusted to maintain the potential of the brush 25 at 0 V or higher. Furthermore, excessive positive charging of the brush 25 can be prevented. If the brush 25 becomes highly positively charged, the substrate W also becomes highly negatively charged due to electrostatic induction, making it easier for negatively charged contaminants to detach from the substrate W. On the other hand, negatively charged contaminants are more likely to be attracted to the brush 25, which increases the frequency of cleaning or replacing the brush 25 and reduces cleaning efficiency. However, in this embodiment, the potential of the brush 25 can be monitored, thereby preventing such problems from occurring.

(Modification)
This embodiment is not limited to the above-described embodiment, and the following modifications are also possible. For example, the charge removal unit is not limited to the electrode 26 provided on the side opposite to the side that contacts the substrate W. As shown in FIG. 8 , an ionizer 28 may be used instead of the electrode 26. Like the surface potential sensor 27, the ionizer 28 can be provided via a fixture 281 at a predetermined distance to the side of the brush 25. The ionizer 28 can emit positive ions generated by, for example, corona discharge, thereby raising the potential of the brush 25 to 0 V or higher. By employing the ionizer 28, the brush 25 can be charged to 0 V or higher over its entire surface, thereby more reliably preventing the surface of the substrate W from being positively charged.

In this case, as in the above embodiment, the output of the ionizer 28 (amount of positive ions emitted) can be adjusted based on monitoring by the surface potential sensor 27 and the charge amount control unit 92, and the potential of the brush 25 can be kept close to 0 V.

In addition, while the surface potential sensor 27 in the above embodiment detects the potential of the brush 25, this is not limited to this. For example, as shown in FIG. 9, the potential of the substrate W may also be detected. In this case, by feeding back the detected potential of the substrate W to the charge amount control unit 92, it is possible to adjust the voltage applied to the electrode 26 or the output of the ionizer 28, for example, based on the relationship between the potential of the substrate W and the potential of the brush 25. In this way, the potential of the brush 25 can be determined indirectly from the potential of the substrate W, making it possible to maintain the potential of the brush 25 within a predetermined range. In the above embodiment, the potential of the brush 25 is measured, so the potential of the substrate W is indirectly inferred. However, in this case, the potential of the substrate W is measured directly, so adhesion of contaminants to the substrate W can be more reliably prevented.

In addition, while the above embodiment employs a charge amount control unit 92 to maintain the potential of the brush 25 within a predetermined range, this is not limited to this. For example, the output from the surface potential sensor 27 may be output to a display device such as a monitor, and a user monitoring this may adjust the voltage applied to the electrode 26 or the output of the ionizer 28 as desired.

In addition, in the above embodiment, the cleaning device 1 was an apparatus that cleans both sides of the substrate W, but the cleaning head 20, brush drive unit 30, and nozzle 41 may be provided on only one side of the substrate W, and the device may clean only one side of the substrate W.

Other Embodiments
Although the embodiments of the present invention and modifications of each part have been described above, these embodiments and modifications of each part are presented as examples and are not intended to limit the scope of the invention. These novel embodiments described above can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and modifications are included within the scope and spirit of the invention, and are also included in the invention described in the claims.

REFERENCE SIGNS LIST 1 Cleaning device 10 Rotation drive unit 10a Roller 11 First holding unit 12 Second holding unit 13 First drive unit 14 Second drive unit 20 Cleaning head 21 Body 22 Motor 23 Brush holder 24 Support 25 Brush 26 Electrode 27 Surface potential sensor 271 Fixing jig 28 Ionizer 281 Fixing jig 30 Brush drive unit 31 Arm 32 Drive mechanism 40 Cleaning liquid discharge unit 41 Nozzle 41a Discharge port 90 Control unit 91 Mechanism control unit 92 Charge amount control unit W Substrate

Claims (5)

a rotation drive unit that rotates the substrate;
a cleaning head that brings a rotating fluorine-based resin brush into contact with the surface of the rotating substrate to clean the surface of the substrate;
a brush driving unit that moves the cleaning head in a direction parallel to the surface of the substrate;
a cleaning liquid discharge unit that discharges an alkaline cleaning liquid onto the substrate from a discharge port;
a static elimination unit that causes the cleaning liquid discharge unit to discharge the cleaning liquid onto the substrate and that causes the brush to have a potential of 0 V while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate by the brush drive unit; and
A cleaning device having: a rotation drive unit that rotates the substrate;
a cleaning head that brings a rotating fluorine-based resin brush into contact with the surface of the rotating substrate to clean the surface of the substrate;
a brush driving unit that moves the cleaning head in a direction parallel to the surface of the substrate;
a cleaning liquid discharge unit that discharges an alkaline cleaning liquid onto the substrate from a discharge port;
a static elimination unit that causes the cleaning liquid discharge unit to discharge the cleaning liquid onto the substrate, and causes the brush drive unit to make the potential of the brush equal to or higher than 0 V while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate;
and
The charge removal unit is an electrode that is provided inside a brush holder that holds the brush, is negatively charged when a voltage is applied, and raises the potential of the brush to 0 V or higher through electrostatic induction. a surface potential sensor that detects the potential of the brush or the potential of the substrate;
a charge amount control unit that adjusts the voltage applied to the electrode based on the potential of the brush or the potential of the substrate;
The cleaning device of claim 2 further comprising: The static eliminator is an ionizer that emits positive ions to the brush.
The cleaning device according to claim 1 . a rotation drive unit that rotates the substrate;
a cleaning head that brings a rotating fluorine-based resin brush into contact with the surface of the rotating substrate to clean the surface of the substrate;
a brush driving unit that moves the cleaning head in a direction parallel to the surface of the substrate;
a cleaning liquid discharge unit that discharges an alkaline cleaning liquid onto the substrate from a discharge port;
a static elimination unit that causes the cleaning liquid discharge unit to discharge the cleaning liquid onto the substrate, and causes the brush drive unit to make the potential of the brush equal to or higher than 0 V while the brush is moving parallel to the surface of the substrate while in contact with the surface of the substrate;
and
the static eliminator is an ionizer that emits positive ions to the brush,
Furthermore,
a surface potential sensor that detects the potential of the brush or the potential of the substrate;
a charge amount control unit that adjusts the output of the ionizer based on the potential of the brush or the potential of the substrate;
A cleaning device having :