JP2023169791A - Grinding device - Google Patents

Abstract

To provide a grinding device that can suppress adhesion of grinding chips to a holding surface of a chuck table in a state where it is not operating so as to hold a workpiece on the holding surface (a non-operational state).SOLUTION: When a chuck table in a non-operational state is positioned at a grinding position, the chuck table is rotated and liquid is supplied to a holding surface of the chuck table. The holding surface is thereby covered with the liquid. As a result, adhesion of grinding chips to the holding surface of the chuck table in the non-operational state is suppressed.SELECTED DRAWING: Figure 5

Description

The present invention relates to a grinding device for grinding a workpiece.

2. Description of the Related Art Device chips such as ICs (Integrated Circuits) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, by dividing a workpiece, such as a wafer, on which a plurality of devices are formed on the front surface into regions containing individual devices.

This workpiece may be thinned prior to its division in order to reduce the size of manufactured chips. A method for thinning the workpiece includes grinding the back side of the workpiece. In addition, in a grinding device for grinding a workpiece, a rough grinding unit for performing rough grinding of the workpiece and a finish grinding unit for performing finish grinding may be provided separately (for example, patent (See Reference 1).

Japanese Patent Application Publication No. 2000-354962

This grinding device generally has a turntable and a plurality of holding surfaces each for holding a workpiece, and is provided on the turntable so as to move as the turntable rotates. Equipped with a chuck table. In this grinding device, by rotating the turntable, the chuck table is sequentially positioned at a rough grinding position where rough grinding of the workpiece is possible and a finish grinding position where finish grinding of the workpiece is possible. .

In addition, in this grinding device, one of the plurality of chuck tables is held on the holding surface of another chuck table when it is not operating (non-operating state) so as to hold the workpiece on the holding surface. Rough grinding or finish grinding of the workpiece may be performed. When rough grinding or finish grinding of a workpiece is performed in this way, the chuck table in an inactive state may be positioned at the finish grinding position or the rough grinding position.

In this case, the grinding debris generated by rough grinding or finish grinding of the workpiece and/or the grinding debris attached to the inner surface of the cover provided to surround the finish grinding position or the rough grinding position are scattered, resulting in a non-operating state. may adhere to the holding surface of the chuck table. When grinding debris adheres to the holding surface of the chuck table, it becomes difficult to hold a new workpiece on the holding surface of the chuck table, and/or it becomes difficult to grind the newly held workpiece. Otherwise, the workpiece may be damaged.

In view of this point, an object of the present invention is to provide a grinding device that can suppress adhesion of grinding debris to the holding surface of a chuck table in a non-operating state.

According to the present invention, there is provided a grinding device for grinding a workpiece, which includes a turntable and a holding surface each for holding the workpiece, and which rotates as the turntable rotates. a first rotation mechanism for rotating each of a plurality of chuck tables provided on the turntable so as to move the chuck table; a second rotation mechanism for rotating a grinding wheel having a grinding wheel for grinding the held workpiece; and a distance between the holding surface of the chuck table positioned at the grinding position and the grinding wheel. a moving mechanism for adjustment; a liquid supply unit for supplying liquid to the holding surface of the chuck table positioned at the grinding position or the workpiece held on the holding surface; and the first rotating mechanism. , a control unit that controls the second rotation mechanism, the movement mechanism, and the liquid supply unit, and the control unit is configured such that the chuck table in an operating state that holds the workpiece on the holding surface is in the grinding position. The first rotation mechanism, the second rotation mechanism, and the A non-operating unit that controls the moving mechanism and also controls the liquid supply unit to supply the liquid to the contact interface between the workpiece and the grinding wheel, and does not hold the workpiece on the holding surface. controlling the first rotation mechanism to rotate the chuck table in the inactive state when the chuck table in the non-operating state is positioned at the grinding position, and supplying the liquid to the holding surface; A grinding device is provided that controls the unit.

Preferably, the control unit controls the second rotation mechanism to rotate the grinding wheel when the non-operating chuck table is positioned at the grinding position, and also controls the second rotation mechanism to rotate the grinding wheel and rotate the holding surface and the grinding wheel. The moving mechanism is controlled so that the holding surface and the grinding wheel are brought close to each other so that they do not come into contact with each other and the liquid supplied to the holding surface also adheres to the grinding wheel.

In the present invention, when the chuck table in a non-operating state is positioned at the grinding position, the chuck table is rotated and liquid is supplied to the holding surface of the chuck table. This causes the holding surface to be coated with the liquid. As a result, adhesion of grinding debris to the holding surface of the chuck table in the non-operating state is suppressed.

FIG. 1 is a perspective view schematically showing an example of a grinding device. FIG. 2 is a sectional view schematically showing an example of the chuck table. FIG. 3 is a partially sectional side view schematically showing an example of a grinding wheel. FIG. 4 is a partially sectional side view schematically showing the operation of the components of the grinding device when the chuck table in operation is positioned at the rough grinding position or the finish grinding position. FIG. 5 is a partially sectional side view schematically showing the operation of the components of the grinding device when the chuck table in the non-operating state is positioned at the rough grinding position or the finish grinding position.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing an example of a grinding device for grinding a workpiece. Note that in FIG. 1, some components of the grinding device are shown as functional blocks. In addition, the X-axis direction (front-back direction) and Y-axis direction (left-right direction) shown in FIG. 1 are directions perpendicular to each other on the horizontal plane, and the Z-axis direction (vertical direction) is This is the direction perpendicular to each (vertical direction).

The grinding device 2 shown in FIG. 1 includes a base 4 that supports various components. On the front end surface of this base 4, cassette tables 6a and 6b are provided. Cassettes 8a and 8b that can accommodate a plurality of workpieces 11 are placed on the cassette tables 6a and 6b.

This workpiece 11 is, for example, a wafer made of a semiconductor material such as silicon. A plurality of devices are arranged in a matrix on the surface 11a side of the workpiece 11. That is, the boundaries of the plurality of devices extend in a grid pattern.

Furthermore, it is preferable that a protective member (not shown) made of resin or the like be attached to the surface 11a of the workpiece 11. In this case, when grinding the back surface 11b side of the workpiece 11, the impact applied to the front surface 11a side can be alleviated and the plurality of devices can be protected.

Further, a recess 4a is formed on the upper surface of the base 4 located slightly behind the cassette tables 6a, 6b. A transport mechanism 10 that can carry out the workpieces 11 from the cassettes 8a, 8b and carry the workpieces 11 into the cassettes 8a, 8b is housed inside the recess 4a.

The transport mechanism 10 has, for example, a plurality of joints and a robot hand, and holds the workpiece 11 on one surface of the robot hand. Further, the transport mechanism 10 is capable of inverting the robot hand holding the workpiece 11, that is, it is possible to turn the workpiece 11 upside down.

Further, a position adjustment mechanism 12 for adjusting the position of the workpiece 11 is provided diagonally rearward of the depression 4a. The position adjustment mechanism 12 includes a disk-shaped position adjustment table and a plurality of pins arranged around the position adjustment table. The workpiece 11 carried out from the cassettes 8a, 8b by the transport mechanism 10 is carried into this position adjustment table, and its center is adjusted to a predetermined position.

Specifically, the workpiece 11 is carried into the position adjustment table with its back surface 11b facing upward. Then, the plurality of pins approach the position adjustment table along the radial direction of the position adjustment table. As a result, the plurality of pins come into contact with the side surface of the workpiece 11 and slightly move the workpiece 11. As a result, the center of the workpiece 11 is aligned to a predetermined position.

Further, on the side of the position adjustment mechanism 12, a conveyance mechanism 14 that holds the workpiece 11 and conveys it rearward is provided. The transport mechanism 14 includes, for example, a support shaft extending in the Z-axis direction, an arm whose base end is fixed to the upper end of the support shaft, and which extends in a direction perpendicular to the Z-axis direction. It has a suction pad fixed to the lower side of the tip of the arm.

Furthermore, the support shaft of the transport mechanism 14 is connected to a rotation mechanism (not shown) such as a motor. When this rotation mechanism operates, the support shaft rotates about a straight line along the Z-axis direction as the rotation axis. Further, the support shaft of the transport mechanism 14 is connected to a moving mechanism (not shown) such as an air cylinder. When this moving mechanism operates, the support shaft moves along the Z-axis direction, that is, the support shaft moves up and down.

For example, the transport mechanism 14 holds and transports the workpieces 11 rearward in the following order. First, the rotation mechanism rotates the support shaft so that the suction pad is positioned directly above the workpiece 11 whose center is aligned to a predetermined position in the position adjustment mechanism 12 . Next, the moving mechanism lowers the support shaft so that the suction pad comes into contact with the workpiece 11.

Next, the suction pad sucks the back surface 11b side (upper surface side) of the workpiece 11 so that the workpiece 11 is held by the suction pad. Next, the moving mechanism raises the support shaft so as to raise the suction pad that holds the workpiece 11. Next, the rotation mechanism rotates the support shaft so as to rotate the suction pad that holds the workpiece 11. As a result, the workpiece 11 is transported rearward.

A turntable 16 is provided at the rear of the transport mechanism 14. This turntable 16 is connected to a rotation mechanism such as a motor (not shown). When this rotation mechanism operates, the turntable 16 is rotated, for example, along the direction of the arrow shown in FIG. rotates.

Further, the turntable 16 is provided with three disc-shaped table bases 18 at approximately equal angular intervals along the circumferential direction of the turntable 16. Note that each table base 18 is rotatable independently of the turntable 16, and is supported by the turntable 16 via a tilt adjustment mechanism (not shown) that adjusts the tilt of the rotation axis of each table base 18. ing.

Furthermore, a chuck table 20 having a holding surface for holding the workpiece 11 is attached to the upper end of each table base 18 . FIG. 2 is a cross-sectional view schematically showing the chuck table 20. As shown in FIG. The chuck table 20 is made of, for example, ceramics, and has a disc-shaped frame 20a that is fixed to the table base 18 using bolts or the like.

A disc-shaped recess is formed in the upper part of the frame 20a, and a disc-shaped porous plate 20b made of porous ceramics or the like is fixed to this recess. Further, the upper surface of the porous plate 20b and the upper surface of the frame 20a surrounding the porous plate 20b are configured to have a shape corresponding to the side surface of a cone, and function as a holding surface for holding the workpiece 11.

Further, each table base 18 is connected to a rotation mechanism (first rotation mechanism) such as a motor (not shown). When the first rotation mechanism operates, the table base 18 and the chuck table 20 attached to the table base 18 rotate about a straight line passing through the center of the holding surface of the chuck table 20 as the rotation axis.

Further, the lower surface side of the porous plate 20b communicates with a suction source (not shown) such as an ejector via a flow path 20c provided inside the frame. Therefore, when the suction source operates with the workpiece 11 placed on the holding surface of the chuck table 20, the workpiece 11 is sucked toward the chuck table 20 and held. That is, in this case, the chuck table 20 is in an operating state holding the workpiece 11.

Note that when the turntable 16 is rotated with the chuck table 20 attached to the table base 18, the table base 18 and the chuck table 20 move. Specifically, in this case, the table base 18 and the chuck table 20 move along the circumferential direction of the turntable 16, for example, along the direction of the arrow shown in FIG.

As a result, the table base 18 and the chuck table 20 are moved in order, for example, to a loading/unloading position adjacent to the transport mechanism 14, a rough grinding position diagonally behind the loading/unloading position, and a finish grinding position to the side of the rough grinding position. It can be positioned in

Then, the workpiece 11 that has been transported rearward by the transport mechanism 14 is loaded into the chuck table 20 positioned at the loading/unloading position. For example, the workpiece 11 is transferred to the chuck table 20 in the following order.

First, a moving mechanism connected to the support shaft of the transport mechanism 14 lowers the support shaft so that the workpiece 11 held by the suction pad of the transport mechanism 14 approaches the holding surface of the chuck table 20 . Next, the suction of the back surface 11b side (upper surface side) of the workpiece 11 by the suction pad is stopped. As a result, the workpiece 11 is separated from the suction pad and transported to the chuck table 20.

Then, when the workpiece 11 is carried into the chuck table 20, the chuck table 20 is brought into operation. That is, in this case, the suction source communicating with the lower surface side of the porous plate 20b is operated so that the surface 11a side (lower surface side) of the workpiece 11 is attracted and held by the chuck table 20. When the workpiece 11 is held on the chuck table 20, the turntable 16 is rotated so that the chuck table 20 holding the workpiece 11 is positioned at the rough grinding position.

A columnar support structure 30 is provided behind each of the rough grinding position and the finish grinding position. A moving mechanism 32 is provided on the front side of the support structure 30. This moving mechanism 32 includes a pair of guide rails 34 extending along the Z-axis direction. Further, a moving plate 36 is slidably attached to the pair of guide rails 34.

Further, a nut (not shown) constituting a ball screw is fixed to the rear side (back side) of the movable plate 36, and a screw shaft 38 extending along the Z-axis direction is fixed to this nut. connected in any possible manner. Further, a motor 40 is connected to one end (upper end) of the screw shaft 38. Then, when the screw shaft 38 is rotated by the motor 40, the moving plate 36 moves along the Z-axis direction together with the nut.

Furthermore, a fixture 42 is provided on the front (surface) of the moving plate 36. A grinding unit 44 is supported by the fixture 42 . This grinding unit 44 includes a spindle housing 46 that is fixed to the fixture 42 . Further, the spindle housing 46 rotatably accommodates a spindle 48 that extends along the Z-axis direction or a direction slightly inclined with respect to the Z-axis direction.

Further, the tip (lower end) of the spindle 48 is exposed from the lower end surface of the spindle housing 46, and a disc-shaped mount 50 is fixed to this lower end. A plurality of holes (not shown) passing through the mount 50 in the thickness direction of the mount 50 are provided at the outer edge of the mount 50, and a bolt 52 is inserted into each hole.

Furthermore, a grinding wheel 54a for rough grinding is attached to the lower surface of the mount 50 of the grinding unit 44 at the rough grinding position using bolts 52. That is, a grinding wheel 54a for rough grinding is attached to the tip of the spindle 48 on the side of the rough grinding position.

Similarly, a grinding wheel 54b for finishing grinding is attached to the lower surface of the mount 50 of the grinding unit 44 at the finishing grinding position using bolts 52. That is, a grinding wheel 54b for finish grinding is attached to the tip of the spindle 48 on the finish grinding position side.

Further, the spindle housing 46 houses a rotation mechanism (second rotation mechanism) such as a motor connected to the base end (upper end) of the spindle 48 . When the second rotation mechanism operates, the grinding wheels 54a, 54b rotate together with the spindle 48 along the Z-axis direction or a direction slightly inclined with respect to the Z-axis direction.

FIG. 3 is a partially sectional side view schematically showing the grinding wheels 54a, 54b, etc. The grinding wheels 54a, 54b include an annular wheel base 56 made of metal such as stainless steel or aluminum. Furthermore, a plurality of grinding wheels 58 are fixed to the lower surface of the wheel base 56 at approximately equal angular intervals along the circumferential direction of the wheel base 56 .

Each of the plurality of grinding wheels 58 includes a binder such as vitrified or resinoid, and abrasive grains such as diamond dispersed in the binder. Note that the average particle size of the abrasive grains included in the grinding wheel 58 included in the grinding wheel 54b for finish grinding is smaller than the average particle size of the abrasive particles included in the grinding wheel 58 included in the grinding wheel 54a for rough grinding.

Furthermore, liquid supply units 60a and 60b are provided near the grinding wheels 54a and 54b. The liquid supply units 60a, 60b include, for example, nozzles 62a, 62b located inside the grinding wheels 54a, 54b in plan view, and a pump (not shown) that supplies liquid such as pure water to the nozzles 62a, 62b. has.

When this pump operates, liquid is supplied from the nozzles 62a, 62b to the holding surface of the chuck table 20 positioned at the rough grinding position or the finish grinding position, or to the workpiece 11 held on this holding surface. Further, in the liquid supply units 60a and 60b, the liquid may be supplied through channels formed in the grinding wheels 54a and 54b instead of or in addition to the nozzles 62a and 62b. good.

Further, when the chuck table 20 that holds the workpiece 11 on the holding surface, that is, the chuck table 20 in the operating state, is positioned at the rough grinding position or the finish grinding position, the back surface 11b side (upper surface side) of the workpiece 11 is Rough grinding or finish grinding is performed.

The operation of the constituent elements of the grinding device 2 when performing rough grinding or finish grinding on the back surface 11b side (upper surface side) of the workpiece 11 will be described later. When the rough grinding and finish grinding of the back surface 11b side (upper surface side) of the workpiece 11 is completed, the turntable 16 is rotated so that the chuck table 20 that holds the workpiece 11 is positioned at the loading/unloading position. .

A transport mechanism 64 that holds the workpiece 11 and transports it forward is provided in front of the loading/unloading position and on the side of the transport mechanism 14 . This transport mechanism 64 has a similar structure to the transport mechanism 14, for example. Then, the transport mechanism 64 transports the workpiece 11, which has undergone rough grinding and finish grinding and is held on the chuck table 20 positioned at the loading/unloading position, forward, for example.

Further, a cleaning unit 66 for cleaning the workpiece 11 carried out from the chuck table 20 is provided on the side of the transport mechanism 64. The cleaning unit 66 includes, for example, a spinner table that rotates while holding the lower surface of the workpiece 11, and a cleaning nozzle that sprays cleaning fluid onto the upper surface of the workpiece 11 held by the spinner table. including.

Note that the cleaning fluid used in the cleaning unit 66 is, for example, a mixed fluid of water and air. Alternatively, the cleaning fluid may include only a liquid such as water. When the cleaning of the workpiece 11 in the cleaning unit 66 is completed, the transport mechanism 10 transports the workpiece 11 from the cleaning unit 66 to the cassettes 8a and 8b.

The components of the grinding device 2 described above are controlled by a control unit 68 built into the grinding device 2. This control unit 68 includes a processing device 68a and a storage device 68b. The processing device 68a is configured by, for example, a processor such as a CPU (Central Processing Unit). Further, the storage device 68b includes, for example, volatile memory such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory), SSD (Solid State Drive) (NAND flash memory), or HDD. (Hard Disk Drive) (magnetic storage device) and other non-volatile memory.

The storage device 68b stores various information (data, programs, etc.) used in the processing device 68a. For example, the storage device 68b stores a grinding device for performing rough grinding or finish grinding on the back surface 11b side of the workpiece 11 when the chuck table 20 in the operating state is positioned at the rough grinding position or the finish grinding position. The configuration of the grinding device 2 is to prevent grinding debris from adhering to the holding surface when the components of the grinding device 2 are operated and the chuck table 20 in an inactive state is positioned at the rough grinding position or the finish grinding position. Programs that operate elements are stored.

Further, the processing device 68a controls the components of the grinding device 2, for example, so as to read and execute the above program stored in the storage device 68b. Each of FIGS. 4 and 5 is a partially sectional side view schematically showing the constituent elements of the grinding device 2 that is controlled by a processing device 68a that reads and executes the above program.

Specifically, FIG. 4 shows the operation of the components of the grinding device 2 when the chuck table 20 in the operating state is positioned at the rough grinding position or the finish grinding position. Further, FIG. 5 shows the operation of the components of the grinding device 2 when the chuck table 20 in the non-operating state is positioned at the rough grinding position or the finish grinding position.

When the chuck table 20 in the operating state is positioned at the rough grinding position or the finish grinding position, the control unit 68 operates the components of the grinding device 2 in the following order. First, the first rotation mechanism and the second rotation mechanism are operated to rotate both the chuck table 20 and the grinding wheels 54a and 54b which are in operation.

Then, the moving mechanism 32 is operated to bring the workpiece 11 into contact with the plurality of grinding wheels 58 while both the chuck table 20 and the grinding wheels 54a and 54b in the operating state are kept rotating. That is, the grinding wheels 54a, 54b are lowered until the workpiece 11 and the plurality of grinding wheels 58 come into contact with each other, while keeping both the chuck table 20 in operation and the grinding wheels 54a, 54b rotating.

Further, the liquid supply units 60a and 60b are operated so that the liquid L is supplied to the workpiece 11 immediately before the workpiece 11 and the plurality of grinding wheels 58 come into contact with each other. As a result, with the liquid being supplied to the contact interface between the workpiece 11 and the plurality of grinding wheels 58, the back surface 11b side (upper surface side) of the workpiece 11 is roughly ground or finished ground.

When the chuck table 20 in the non-operating state is positioned at the rough grinding position or the finish grinding position, the control unit 68 operates the components of the grinding device 2 in the following order. First, the first rotation mechanism and the second rotation mechanism are operated to rotate both the chuck table 20 and the grinding wheels 54a and 54b, which are in a non-operating state.

Then, while both the chuck table 20 and the grinding wheels 54a and 54b in the non-operating state are kept rotating, the holding surface of the chuck table 20 and the plurality of grinding wheels 58 do not come into contact with each other, and the grinding wheels 58 are not supplied to the holding surface. The moving mechanism 32 is operated to bring the holding surface and the plurality of grinding wheels 58 closer together so that the liquid L also adheres to the plurality of grinding wheels 58.

That is, while both the chuck table 20 and the grinding wheels 54a, 54b in the non-operating state are kept rotating, the holding surface of the chuck table 20 and the plurality of grinding wheels 58 are positioned slightly apart from each other, for example. The grinding wheels 54a, 54b are lowered so that the distance between the two is 2 mm or less.

Further, when the holding surface of the chuck table 20 and the plurality of grinding wheels 58 are positioned slightly apart, the liquid supply units 60a and 60b are operated so that the liquid L is supplied to this holding surface. As a result, this holding surface is covered with the liquid L. As a result, adhesion of grinding debris to the holding surface of the chuck table 20 in the non-operating state is suppressed.

Furthermore, this liquid L also adheres to the plurality of grinding wheels 58. Therefore, adhesion of grinding debris to the plurality of grinding wheels 58 is also suppressed. Thereby, when the workpiece 11 is newly subjected to rough grinding or finish grinding using the plurality of grinding wheels 58, the probability that the workpiece 11 will be damaged can be reduced.

Note that the content described above is one aspect of the present invention, and the content of the present invention is not limited to the content described above. For example, in the present invention, when the chuck table 20 in the non-operating state is positioned at the rough grinding position or the finish grinding position, the grinding wheels 54a, 54b are not rotated, and/or the holding surface of the chuck table 20 is It is not necessary to bring the plurality of grinding wheels 58 close to each other.

Further, in the present invention, the turntable 16 may be provided with a plurality of chuck tables of different types. For example, in the present invention, the turntable 16 may be provided with a plurality of chuck tables that can hold workpieces of different sizes on their respective holding surfaces.

In addition, the structure, method, etc. according to the embodiments described above can be modified and implemented as appropriate without departing from the scope of the objective of the present invention.

2: Grinding device 4: Base (4a: hollow)
6a, 6b: Cassette table 8a, 8b: Cassette 10: Transport mechanism 12: Position adjustment mechanism 14: Transport mechanism 16: Turntable 18: Table base 20: Chuck table (20a: frame, 20b: porous plate, 20c: flow road)
30: Support structure 32: Movement mechanism 34: Guide rail 36: Movement plate 38: Screw shaft 40: Motor 42: Fixture 44: Grinding unit 46: Spindle housing 48: Spindle 50: Mount 52: Bolt 54a, 54b: Grinding wheel 56: Wheel base 58: Grinding wheel 60a, 60b: Liquid supply unit 62a, 62b: Nozzle 64: Transport mechanism 66: Cleaning unit 68: Control unit (68a: processing device, 68b: storage device)

Claims (2)

A grinding device for grinding a workpiece,
turntable and
A chuck table for rotating each of a plurality of chuck tables provided on the turntable, each having a holding surface for holding the workpiece, and moving as the turntable rotates. a first rotation mechanism;
a second rotation mechanism for rotating a grinding wheel having a grinding wheel for grinding the workpiece held on the holding surface of the chuck table positioned at the grinding position among the plurality of chuck tables;
a moving mechanism for adjusting the distance between the holding surface of the chuck table positioned at the grinding position and the grinding wheel;
a liquid supply unit for supplying liquid to the holding surface of the chuck table positioned at the grinding position or to the workpiece held on the holding surface;
A control unit that controls the first rotation mechanism, the second rotation mechanism, the movement mechanism, and the liquid supply unit,
The control unit includes:
When the working chuck table holding the workpiece on the holding surface is positioned at the grinding position, the workpiece and the grinding are rotated while both the working chuck table and the grinding wheel are rotated. controlling the first rotating mechanism, the second rotating mechanism, and the moving mechanism so as to bring the grinding wheel into contact with the grinding wheel; and supplying the liquid so as to supply the liquid to the contact interface between the workpiece and the grinding wheel. control the unit,
controlling the first rotation mechanism to rotate the chuck table in the non-operating state when the chuck table in the non-operating state that is not holding the workpiece on the holding surface is positioned at the grinding position; , a grinding device that controls the liquid supply unit to supply the liquid to the holding surface. The control unit controls the second rotation mechanism to rotate the grinding wheel when the non-operating chuck table is positioned at the grinding position, and causes the holding surface and the grinding wheel to come into contact with each other. Grinding according to claim 1, wherein the moving mechanism is controlled so that the holding surface and the grinding wheel are brought close to each other so that the liquid supplied to the holding surface also adheres to the grinding wheel. Device.

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