JP2024025910A - Washing device - Google Patents

Abstract

To shorten a cleaning time in a washing device that sprays two fluids, which are a mixture of water and air.SOLUTION: A washing device 10 that sprays two fluids F, which are a mixture of water and air, from a two-fluid nozzle 14 placed above an object to be cleaned (for example, a wafer W or a porous plate 32) to clean the upper surface of the object to be cleaned includes a plate 11 arranged above the top surface of the object to be cleaned with a gap G, and an opening 111 that is formed in the plate 11 and allows the two fluids F sprayed from the two-fluid nozzle 14 to pass through the area without being obstructed and sprayed onto the object to be cleaned. The two fluids F that passed through the opening 111 are sprayed onto the top surface of the object to be cleaned, and then the water flows radially through a gap G between the upper surface of the object to be cleaned and the lower surface of the plate 11 in a direction away from the opening 111, thereby cleaning the object to be cleaned.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cleaning device that cleans the upper surface of an object to be cleaned by spraying two fluids, each of which is a mixture of water and air, from a two-fluid nozzle.

Conventionally, the top surface of a wafer is cleaned by jetting two fluids, which are a mixture of water and air, from a two-fluid nozzle toward the top surface of a wafer held on a chuck table.

The two fluids injected from the two-fluid nozzle may be reflected on the upper surface of the wafer and scattered into the processing equipment. In order to prevent the scattering, a cleaning device has been proposed that includes a box surrounding a two-fluid nozzle, scatters the two fluids in the box, and separates the two fluids into gas and liquid (for example, Patent Documents 1 and 2 reference).

Japanese Patent Application Publication No. 2011-200785 JP 2017-135343 Publication

When a box surrounding the two-fluid nozzle is used as described above, a water layer is formed on the top surface of the wafer surrounded by the box. Therefore, the force of the two fluids injected from the two-fluid nozzle is blocked by the water layer, and the cleaning area becomes smaller. This poses a problem in that the cleaning time becomes longer. This problem occurs not only when the object to be cleaned is a wafer, but also when the object to be cleaned is another workpiece or a chuck table itself that holds the workpiece by suction.

An object of the present invention is to shorten the cleaning time in a cleaning device that sprays two fluids that are a mixture of water and air.

In one embodiment, the cleaning device is a cleaning device that cleans the upper surface of the object by spraying two fluids, each of which is a mixture of water and air, from a two-fluid nozzle placed above the object. A plate disposed with a gap above the upper surface of the object to be cleaned, and an opening formed in the plate to allow the area of the two fluids injected from the two-fluid nozzle to pass through without interfering with the two fluids to be sprayed onto the object to be cleaned. The two fluids passing through the opening are sprayed onto the upper surface of the object to be cleaned, and then radially spread through the gap between the upper surface of the object to be cleaned and the lower surface of the plate in a direction away from the opening. It flows and washes the object to be washed.

According to the aspect, the cleaning time can be shortened in the cleaning device that sprays two fluids that are a mixture of water and air.

FIG. 1 is a perspective view showing a cleaning device and the like according to an embodiment. It is a top view for explaining the flow of two fluids from the opening of a plate in one embodiment. FIG. 3 is a front view for explaining the ejection of two fluids by three two-fluid nozzles in one embodiment. FIG. 3 is a plan view for explaining the flow of two fluids injected by three two-fluid nozzles in one embodiment. FIG. 2 is a front view schematically showing the internal structure of the cleaning device in one embodiment (when the object to be cleaned is a chuck table). FIG. 2 is a front view schematically showing the internal structure of the cleaning apparatus in one embodiment (when the object to be cleaned is the upper surface of a wafer).

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a cleaning device 10 and the like according to an embodiment.

Note that the X-axis direction, Y-axis direction, and Z-axis direction shown in FIG. 1 and each of FIGS. 2 to 6 described later are perpendicular to each other. The X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is an up-down direction (vertical direction). In each figure, of the double arrows indicating the X-axis direction, the side marked with +X is the front, and the side marked with -X is the rear. Of the double arrows indicating the Y-axis direction, the +Y side is the left side, and the side marked with -Y is the right side. Of the double arrows indicating the Z-axis direction, the side marked with +Z is defined as the upper side, and the side marked with -Z is defined as the lower side.

As shown in FIG. 1, the cleaning device 10 is disposed integrally with a base portion 20, a chuck table 30, a grinding mechanism 40, and a grinding lifting mechanism 50. The cleaning device 10 cleans objects to be cleaned, such as the chuck table 30 itself (see FIG. 5) and the wafer W held by suction by the chuck table 30 (see FIG. 6). Further, the cleaning device 10 can clean not only the wafer W that has been ground by the grinding mechanism 40 but also any workpiece (object to be cleaned) such as a ceramic substrate or a package substrate.

Note that the cleaning device 10 can be regarded as a cleaning device even when it integrally includes at least one of the base portion 20, the chuck table 30, and the grinding mechanism 40, and can also be regarded as a cleaning system. Further, a device including at least the cleaning device 10 and the grinding mechanism 40 can be regarded as a grinding device or a grinding system. Furthermore, if the grinding mechanism 40 is considered as an example of a processing mechanism, a device including at least the cleaning device 10 and the processing mechanism can be considered as a processing device.

The cleaning device 10 includes a plate 11, a box 12, a two-fluid nozzle 14, an elevating section 15, a horizontal moving section 16, an air source 17, a water source 18, and a control section 19 shown in FIG. 5, which will be described later. Be prepared.

The plate 11 has a rectangular or circular plate shape, for example, and is arranged horizontally parallel to the upper surface of the object to be cleaned (surface to be cleaned) so as to extend in the X-axis direction and the Y-axis direction. An opening 111 shown in FIGS. 2 to 4 is formed in the plate 11 so as to pass through it in the vertical direction.

For example, one opening 111 is formed directly below one two-fluid nozzle 14. The opening 111 is preferably formed in a shape larger than the area of the two fluids F to be injected, in order to allow the area of the two fluids F injected from the two-fluid nozzle 14 to pass through without being obstructed. Note that the shape of the opening 111 may be appropriately set according to the shape of the injection port of the two-fluid nozzle 14, but if the injection port of the two-fluid nozzle 14 has a circular shape, it may be circular, and if the injection port has a rectangular shape, it may be set as appropriate. It is best to make it rectangular. Further, the number of two-fluid nozzles 14 is arbitrary, but when only one two-fluid nozzle 14 is arranged, only one opening 111 is provided, and as shown in FIGS. 3 and 4, the two-fluid nozzle 14 When three openings 111 are arranged, three openings 111 are preferably provided.

Moreover, the opening 111 is formed in a size that does not obstruct the area of the two fluids F that are injected from the injection port and are in the shape of a conical or pyramidal shape that widens toward the end and are injected onto the surface to be cleaned.

The box 12 has four side plates 121 surrounding the two-fluid nozzle 14 and a top plate 122 connected to the upper ends of these side plates 121. The side plates 121 include, for example, a front plate fixed to the upper part of the front end of the plate 11 , a left side plate fixed to the upper part of the left end of the plate 11 , a right side plate fixed to the upper part of the right end of the plate 11 , and a right side plate fixed to the upper part of the right end of the plate 11 . There are four in total, including a back plate fixed to the upper part of the rear end.

Since the space inside the box 12 is covered by the plate 11 and the box 12 (the four side plates 121 and the top plate 122), the air pressure in the space inside the box 12 is reduced by the injection of two fluids F by the two-fluid nozzle 14, which will be described later. increases. Therefore, an exhaust port 123 shown by a broken line (hidden line) in FIG. 1 is formed in the side plate 121 which is a back plate. This exhaust port 123 may be formed in the top plate 122 or another side plate 121. Further, when the box 12 itself (or at least one of the side plates 121 and the top plate 122) is omitted, the exhaust port 123 is omitted.

The two-fluid nozzle 14 injects, for example, vertically downward the two-fluid F shown in FIG. 3, which is a mixture of water and air. The two-fluid nozzle 14 may be fixed to the box 12 or the plate 11 directly or indirectly inside the box 12. As a result, the plate 11, the box 12, and the two-fluid nozzle 14 are moved up and down and horizontally as a unit by the driving of the lifting section 15 and the horizontal moving section 16, which will be described later. Note that the air (high pressure air) mixed with the two fluids F is supplied as air from an air source 17 shown in FIG. 5, and the water mixed with the two fluids F is supplied from a water source 18 shown in FIG. The water may be a liquid such as a cleaning solution with additives added.

In addition, when the two-fluid nozzle 14 is indirectly arranged on the box 12 or the plate 11, a nozzle elevating mechanism that moves the two-fluid nozzle 14 toward and away from the surface to be cleaned is provided to reduce the distance from the surface to be cleaned. May be adjusted.

As described above, since the opening 111 is formed in the plate 11, the two fluids F ejected by the two-fluid nozzle 14 pass through the opening 111 and clean the porous plate shown in FIG. 5, which is an example of the object to be cleaned. 32 (chuck table 30) or the upper surface Wa of the wafer W shown in FIG. The sprayed two fluids F flow radially through the gap G between the upper surface of the object to be cleaned and the lower surface of the plate 11 in a direction away from the opening 111 as shown in FIGS. 2 and 4. As a result, the object to be cleaned is cleaned. When a plurality of openings 111 are formed as shown in FIG. 4, the two fluids F jetted from adjacent openings 111 may interfere with each other, but the two fluids F generally flow radially. Note that the two fluids F need only be radial at least immediately after being injected toward the object to be cleaned through the opening 111. Further, in FIG. 2, the plate 11 is illustrated in a circular shape by a two-dot chain line (imaginary line), but the plate 11 has a rectangular plate shape, for example, as shown in FIG. However, the shape of the plate 11 is arbitrary.

The elevating section 15 shown in FIG. 1 is an air cylinder as an example of elevating means (actuator). Two rods 151 protrude downward from the lower part of the elevating section 15. Rod 151 is connected to box 12. Therefore, when the two rods 151 move up and down by the drive of the air cylinder, the box 12, the plate 11 and the two-fluid nozzle 14 fixed to the box 12 move up and down. Note that the structure of the elevating section 15 is arbitrary, and is not limited to an air cylinder, but may be any structure that allows the plate 11 to be moved up and down.

The horizontal moving unit 16 includes a motor 161, a ball screw 162, a slider 163, and a pair of upper and lower guide rails 164.

The motor 161 is arranged at the right end of the ball screw 162 and rotates the ball screw 162. This ball screw 162 is arranged in the Y-axis direction, and when the ball screw 162 rotates, a slider 163 screwed into the ball screw 162 moves in the Y-axis direction along two guide rails 164. The above-mentioned elevating section 15 is fixed to the slider 163. Therefore, when the slider 163 moves horizontally in the Y-axis direction, the elevating section 15 and the box 12, plate 11, and two-fluid nozzle 14 connected to the elevating section 15 move horizontally. A pair of upper and lower guide rails 164 are fixed to a gate-shaped frame 24 of the base portion 20, which will be described later, and extend in the Y-axis direction at the upper and lower portions of the ball screw 162, respectively. In addition, the structure of the horizontal movement part 16 is arbitrary, and should just horizontally move the plate 11.

As mentioned above, the air source 17 shown in FIG. 5 supplies air to the two-fluid nozzle 14, and the water source 18 supplies water to the two-fluid nozzle 14. Two fluids F are generated by mixing these air and water.

The control unit 19 includes a processor (for example, a CPU: Central Processing Unit) that functions as an arithmetic processing unit that controls the operation of each part of the cleaning device 10, and a ROM (ROM) that is a read-only semiconductor memory in which a predetermined control program is recorded in advance. It has memories such as RAM (Random Access Memory), which is a semiconductor memory that can be written and read at any time and is used as a working storage area as needed when the processor executes various control programs. Note that the control unit 19 may be provided, for example, in each of the two-fluid nozzle 14, the lifting unit 15, the horizontal movement unit 16, etc., and the cleaning device 10 may include a plurality of control units 19. Further, the control section 19 of the cleaning device 10 may also serve as a control section of another device (for example, the grinding mechanism 40). Furthermore, a control section of another device may also serve as the control section 19 of the cleaning device 10, or a control section that controls the cleaning device 10 and the other device may be provided.

The base portion 20 shown in FIG. 1 includes a base 21, a moving plate 22, a waterproof cover 23, a gate-shaped frame 24, and a column 25.

The base 21 has a rectangular parallelepiped shape with its longitudinal direction in the X-axis direction. A part of the upper surface of the base 21 is opened in a rectangular shape that is long in the X-axis direction. A moving plate 22 is disposed in this opening so as to be movable in the X-axis direction. The moving plate 22 is arranged horizontally, has a rectangular frame shape surrounding a chuck table 30, which will be described later, and moves in the X-axis direction together with the chuck table 30. The waterproof cover 23 is provided in a bellows shape to close the above-mentioned opening of the base 21. The gate-shaped frame 24 connects two vertical parts of the upper surface of the base 21 that extend upward from positions separated in the Y-axis direction across the opening part, and the upper ends of these two vertical parts, and one horizontal portion extending in the Y-axis direction. A pair of upper and lower guide rails 164 of the horizontal moving section 16 described above are fixed to the horizontal portion of the gate-shaped frame 24 . The column 25 is arranged at the rear of the upper surface of the base 21. The column 25 has a rectangular parallelepiped shape with its longitudinal direction in the Z-axis direction.

The chuck table 30 has a frame 31 and a porous plate 32. The chuck table 30 is rotated about the Z-axis direction by a table rotation mechanism (not shown) disposed inside the base portion 20 . Further, the chuck table 30 is moved in the X-axis direction in the opening of the base 21 by a table moving mechanism (not shown) disposed inside the base portion 20 .

The frame 31 has a disk shape, and as shown in FIG. 5, a recess 311 is provided on the upper surface. Further, the frame body 31 is provided with a communication path 312 extending between the recess 311 and the lower end of the chuck table 30. This communication path 312 is connected to a suction source (not shown) and functions as a suction path for suctioning air from the recess 311 .

The porous plate 32 has a disk shape and is accommodated in the recess 311 of the frame 31. The porous plate 32 is made of a porous material such as ceramics, and fine pores are formed throughout. With the porous plate 32 attached in the recess 311 of the frame 31, the upper surface of the frame 31 and the upper surface of the porous plate 32 are flush with each other. The upper surface of the porous plate 32 constitutes a holding surface 321 that suctions and holds the wafer W by suctioning air through the communication path 312 described above.

The grinding mechanism 40 shown in FIG. 1 includes a spindle 41, a spindle housing 42, a holder 43, a spindle motor 44, a mount 45, a grinding wheel 46, and a grindstone 47.

The spindle 41 rotates around the Z-axis direction. Spindle housing 42 rotatably supports spindle 41. The holder 43 is fixed to a slider 53 of a grinding lifting mechanism 50, which will be described later, and holds the spindle housing 42. A spindle motor 44 rotates the spindle 41. A mount 45 is attached to the lower end of the spindle 41. Grinding wheel 46 is mounted on mount 45. The grindstone 47 is annularly provided on the lower surface of the grinding wheel 46 and grinds a workpiece such as a wafer W held by suction on the holding surface 321 of the chuck table 30 . Note that the wafer W that has been ground moves in the X-axis direction together with the chuck table 30 so as to be located directly below the two-fluid nozzle 14.

The grinding elevating mechanism 50 includes a motor 51, a ball screw 52, a slider 53, and a pair of left and right guide rails 54.

The motor 51 is arranged at the upper end of the ball screw 52 and rotates the ball screw 52. This ball screw 52 is arranged in the Z-axis direction, and when the ball screw 52 rotates, a slider 53 that is screwed into the ball screw 52 moves in the Z-axis direction along the two guide rails 54. The holder 43 of the grinding mechanism 40 is fixed to the slider 53 as described above. A pair of left and right guide rails 54 are fixed to the above-mentioned column 25 and extend in the Z-axis direction at the right and left parts of the ball screw 52, respectively.

Here, the ejection of the two fluids F in the cleaning device 10 will be described while omitting matters that overlap with the above description. Note that the object to be cleaned is the porous plate 32 (chuck table 30) in the example of FIG. 5, and the wafer W in the example of FIG.

First, as shown in FIG. 5, the control unit 19 controls the horizontal moving unit 16, and the lifting unit 15, the box 12, the plate 11, and the plate 12 that move horizontally (in the Y-axis direction) together with the lifting unit 15. The fluid nozzle 14 is moved in the Y-axis direction to an arbitrary cleaning position of the two-fluid nozzle 14.

Next, the control unit 19 controls the elevating unit 15 to move the box 12 and the plate 11 and two-fluid nozzle 14 that move up and down together with the box 12 into the gap between the lower surface of the plate 11 and the holding surface 321 of the porous plate 32. G is raised and lowered to a preset gap. This set gap is preferably narrower than the height of the water layer of the two fluids F formed on the holding surface 321 of the porous plate 32 when the plate 11 is not disposed, and is 1 mm or 2 mm, for example. Note that if the upper surface of the object to be cleaned is not horizontal, the shape of the lower surface of the plate 11 may not be flat but parallel to the upper surface of the object to be cleaned. Moreover, the setting gap of the gap G may become larger or smaller as the distance from the opening 111 increases depending on the shape of the upper surface of the object to be cleaned and the shape of the lower surface of the plate 11.

Next, the control unit 19 controls the two-fluid nozzle 14 to inject the two-fluid F from the two-fluid nozzle 14 . Since the opening 111 is formed in the plate 11 directly below the two-fluid nozzle 14, the two-fluid F passes through the opening 111 and fills the gap G between the holding surface 321 of the porous plate 32 and the lower surface of the plate 11. As shown in FIGS. 2 and 4, the water flows radially away from the opening 111 and cleans the porous plate 32. As a result, debris such as grinding debris on the holding surface 321 is removed. Note that during the cleaning process, the two-fluid nozzle 14 may be moved in the Y-axis direction by the horizontal moving unit 16, and the chuck table 30 may be moved or rotated in the X-axis direction, as appropriate.

Even when the object to be cleaned is a wafer W held by suction on the holding surface 321 of the chuck table 30 as shown in FIG. Debris such as grinding debris on the upper surface Wa is removed. The cleaned wafer W is transported to a storage cassette or other device by a robot arm (not shown) or the like.

As shown in FIG. 6, an air source 61 and a water source 62 that communicate with the communication path 312 of the frame body 31 may be arranged below the chuck table 30. In this case, the lower surface of the object to be cleaned (the wafer W in FIG. 6) can be cleaned by the air supplied by the air source 61 and the water supplied by the water source 62. Note that even when the object to be cleaned is the porous plate 32 (chuck table 30), the porous plate 32 can be similarly cleaned from below by the air supplied by the air source 61 and the water supplied by the water source 62. .

In the embodiment described above, the cleaning apparatus 10 sprays a two-fluid F, which is a mixture of water and air, from a two-fluid nozzle 14 disposed above the object to be cleaned (for example, the wafer W or the chuck table 30). A cleaning device 10 that cleans the upper surface of an object to be cleaned with a plate 11 disposed above the upper surface of the object with a gap G, and two fluids formed on the plate 11 and sprayed from a two-fluid nozzle 14. An opening 111 is provided that allows the spray to pass through the area F without interfering with the object to be cleaned. The two fluids F that have passed through the opening 111 are sprayed onto the top surface of the object to be cleaned, and then flow radially through the gap G between the top surface of the object to be cleaned and the bottom surface of the plate 11 in a direction away from the opening 111, and are then sprayed onto the top surface of the object to be cleaned. Wash the laundry.

By arranging the plate 11 in which the opening 111 is formed in this way, it is possible to prevent a water layer from being formed on the upper surface of the object to be cleaned and the momentum of the two fluids F being obstructed by the water layer. Moreover, since the flow path of the two fluids F sprayed onto the object to be cleaned is defined by the gap G between the plate 11 and the upper surface of the object to be cleaned, the two fluids F can easily flow over the upper surface of the object to be cleaned. Therefore, the momentum of the two fluids F is not hindered, thereby preventing a decrease in cleaning power. Therefore, according to this embodiment, the cleaning time can be shortened. Furthermore, by arranging the plate 11, it is also possible to suppress the two fluids F injected from the two fluid nozzle 14 from rebounding and scattering from the object to be cleaned.

Further, in the present embodiment, the cleaning device 10 includes, for example, four side plates 121 surrounding the two-fluid nozzle 14 and a top plate 122 connected to the upper end of the side plates 121. 121 (or a top plate 122), and the plate 11 is connected to the lower end of the box 12.

Therefore, the air pressure in the space inside the box 12 can be suppressed from increasing due to the injection of the two-fluid F from the two-fluid nozzle 14 by exhausting air from the exhaust port 123. Thereby, it is possible to prevent the two-fluid nozzle 14 from interfering with the injection of the two-fluid F due to an increase in the atmospheric pressure in the space inside the box 12 . Therefore, the cleaning time can be further shortened.

Further, in the present embodiment, the cleaning device 10 includes a lifting section 15 that is an example of a lifting means for lifting and lowering the plate 11, and the object to be cleaned is mounted on a holding surface 321 or a holding surface 321 of a table (for example, the chuck table 30). The cleaning device 10 cleans the upper surface of a workpiece (for example, a wafer W) held by a A control unit 19 is provided to control the elevating unit 15 so that the gap G between the lift and the lift unit 15 becomes a preset gap.

As a result, the gap between the lower surface of the plate 11 and the upper surface of the object to be cleaned is adjusted according to the ease of flow of the two fluids F, which varies depending on, for example, the injection amount of the two fluids F and the material of the plate 11 and the object to be cleaned. G can be adjusted. Therefore, the two fluids F injected by the two-fluid nozzle 14 can easily flow through the gap G between the plate 11 and the object to be cleaned, and the cleaning time can be further shortened.

In this embodiment, the plate 11 has an area smaller than the surface to be cleaned, but may have an area larger than the surface to be cleaned. By arranging the plate 11 with an area larger than the surface to be cleaned, a gap G is formed over the entire surface to be cleaned, and the two fluids F are discharged from the outer periphery of the surface to be cleaned. It is possible to prevent dirt from re-adhering to the surface to be cleaned.

It goes without saying that the cleaning device according to the present invention is not limited to the above-described embodiments, and may be implemented in various different forms within the scope of the technical idea. Further, the shapes of each structure illustrated in the accompanying drawings are not limited to these, and can be changed as appropriate within the range that can achieve the effects of the present invention.

As described above, in the present invention, the cleaning time can be shortened in a cleaning device that injects two fluids F that are a mixture of water and air. Therefore, it is particularly useful for cleaning workpieces such as wafers and for cleaning chuck tables that hold workpieces by suction.

10: Cleaning device 11: Plate 111: Opening 12: Box 121: Side plate 122: Top plate 123: Exhaust port 14: 2 fluid nozzles 15: Lifting section (lifting means)
151: Rod 16: Horizontal moving part (moving means)
161: Motor 162: Ball screw 163: Slider 164: Guide rail 17: Air source 18: Water source 19: Control section 20: Base section 21: Base 22: Moving plate 23: Waterproof cover 24: Portal frame 25: Column 30: Chuck table 31: Frame 311: Recess 312: Communication path 32: Porous plate 321: Holding surface 40: Grinding mechanism 41: Spindle 42: Spindle housing 43: Holder 44: Spindle motor 45: Mount 46: Grinding wheel 47: Grinding wheel 50 : Grinding lifting mechanism 51: Motor 52: Ball screw 53: Slider 54: Guide rail 61: Air source 62: Water source F: 2 fluid G: Gap W: Wafer Wa: Top surface

Claims (3)

A cleaning device that cleans the upper surface of an object to be cleaned by jetting two fluids mixed with water and air from a two-fluid nozzle arranged above the object to be cleaned, the cleaning device comprising:
a plate disposed with a gap above the top surface of the object to be cleaned;
an opening formed in the plate that allows the two fluids sprayed from the two fluid nozzle to pass through the area without being obstructed and spray onto the object to be cleaned;
The two fluids that have passed through the opening are sprayed onto the upper surface of the object to be cleaned, and then flow radially through the gap between the upper surface of the object to be cleaned and the lower surface of the plate in a direction away from the opening. A cleaning device that cleans objects to be cleaned. A box surrounding the two-fluid nozzle is formed by a side plate surrounding the two-fluid nozzle and a top plate connected to the upper end of the side plate, and an exhaust port formed in the top plate or the side plate,
The cleaning device of claim 1, wherein the plate is connected to a lower end of the box. Elevating means for elevating and lowering the plate;
The object to be cleaned is the holding surface of the table or the upper surface of the workpiece held on the holding surface,
comprising a control unit that controls the elevating means so that the gap between the holding surface and the lower surface of the plate and the gap between the upper surface of the workpiece and the lower surface of the plate become preset gaps;
The cleaning device according to claim 1 or 2.