JP2021000675A - Dressing method - Google Patents

Abstract

To prevent excessive wear of a grinding grindstone in dressing.SOLUTION: A dressing method for dressing a grinding grindstone arranged on a lower surface side of an annular grinding wheel, comprises: a holding step of holding a dresser board with a holding surface of a holding table; a dressing starting step of starting dressing of the grinding grindstone by grinding and feeding the grinding wheel in a direction of approaching the holding table while rotating the grinding wheel around a prescribed axis of rotation and pushing the grinding grindstone against the dresser board held by the holding table; and a grinding feed stopping step of measuring a load on the holding table via a load measuring unit and stopping the grinding and feeding when an amount of variation in the load in a prescribed period after the dressing starting step becomes equal to a prescribed value or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dressing method for dressing a grinding wheel.

A method of processing the back surface side of a wafer in which an IC (Integrated Circuit), LSI (Large Scale Integration) or the like is formed on the front surface side by using a grinding device is known. The grinding device includes a grinding unit for grinding a wafer, and the back surface side of the workpiece is ground by this grinding unit.

The grinding unit has a spindle on which a motor is mounted on the upper end side. A disk-shaped wheel mount is fixed to the lower end side of the spindle. Further, the upper surface side of the annular grinding wheel is mounted on the lower surface side of the wheel mount. On the lower surface side of the grinding wheel, for example, a plurality of grinding wheels are arranged in an annular shape.

The grinding unit is connected to a ball screw type grinding feed unit, and the grinding feed unit moves the grinding unit in the vertical direction. Further, below the grinding unit, a chuck table for sucking and holding the wafer is provided so as to face the grinding wheel.

When grinding the back surface side of a wafer using a grinding device, first, the chuck table is rotated in a predetermined direction while the front surface side of the wafer is held by the chuck table. Then, with the grinding wheel rotated in the same direction as the chuck table, the grinding unit is moved downward (grinding feed direction) using the grinding feed unit. When the lower surface side of the grinding wheel is pressed against the back surface side of the wafer, the back surface side of the wafer is ground by the grinding wheel.

The grinding wheel is formed by mixing abrasive grains such as diamond and cBN (cubic boron nitride) with a binder such as vitrify and resinoid and sintering the grinding wheel. When a wafer is ground with this grinding wheel, a large number of abrasive grains protruding from the surface (that is, the grinding surface) of the grinding wheel act as cutting edges.

However, as the grinding progresses, the grinding wheel wears, and the grinding performance may deteriorate due to spillage, clogging, clogging, etc. of the abrasive grains. As a method of determining whether or not the grinding performance of the grinding wheel has deteriorated, there is a method of detecting a grinding abnormality of the grinding unit.

Specifically, the current value of the motor that rotates the grinding wheel is taken in, and this current value or the like is converted into the grinding resistance value according to a predetermined conversion method. Then, the grinding abnormality is detected by using the waveform of the grinding resistance value (see, for example, Patent Document 1).

In order to restore the grinding performance, the dresser board is held by the chuck table instead of the wafer, and the grinding wheel is dressed by the dresser board. In dressing, for example, so-called sharpening for exposing the abrasive grains of the grinding wheel from the bond material and so-called trueing for adjusting the shape, height, etc. of the grinding wheel are performed. By dressing, the grinding performance of the grinding wheel is restored.

However, at present, there is no clear judgment method for confirming that the dressing of the grinding wheel has been completed. Further, it is considered that the appropriate amount of wear of the grinding wheel in the dressing depends on the type of the grinding wheel and the type of the dresser board used.

In the past, the amount of wear of the grinding wheel was set to be large so that the grinding performance could be restored regardless of the combination of the grinding wheel and the dresser board. For example, regardless of the combination of the grinding wheel and the dresser board, the grinding wheel was dressed so that the grinding wheel wears a certain amount (for example, 100 μm or more and 200 μm or less).

Japanese Unexamined Patent Publication No. 9-29630

However, when the grinding wheel is worn by a certain amount regardless of the combination of the grinding wheel and the dresser board, the grinding wheel is excessively worn.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent excessive wear of the grinding wheel in dressing.

According to one aspect of the present invention, a dressing method for dressing a grinding wheel provided on the lower surface side of an annular grinding wheel, the holding step of holding the dresser board on the holding surface of the holding table, and the grinding wheel. By grinding and feeding the grinding wheel in a direction approaching the holding table and pressing the grinding wheel against the dresser board held by the holding table while rotating the grinding wheel around a predetermined rotation axis. When the dressing start step for starting the dressing of the grinding wheel and the load on the holding table are measured by the load measuring unit and the fluctuation amount of the load for a predetermined period after the dressing start step becomes equal to or less than a predetermined value. A dressing method comprising a grinding feed stopping step of stopping the grinding feed is provided.

In the initial stage of dressing, the grinding wheel that has not been sufficiently trued or the like comes into contact with the dresser board, so that the contact area between the abrasive grains of the grinding wheel and the dresser board is relatively small. At this time, the amount of wear of the dresser board is relatively small, and the load applied to the dresser board and the holding table is also relatively low.

However, as the grinding wheel is dressed, the contact area between the abrasive grains of the grinding wheel and the dresser board gradually increases, and the load applied to the dresser board and the holding table gradually increases. Further, as the dresser board is gradually worn, the grinding performance of the grinding wheel is restored. When the grinding wheel is sufficiently dressed, the amount of wear on the dresser board per unit time becomes substantially constant. At this time, the load applied to the dresser board and the holding table has a substantially constant value in which the amount of fluctuation in a predetermined period is equal to or less than a predetermined value.

Therefore, in the dressing method according to one aspect of the present invention, the load on the chuck table is measured by the load measuring unit, and when the fluctuation amount of the load for a predetermined period after the dressing start step becomes equal to or less than a predetermined value, grinding feed To stop. This makes it possible to prevent excessive wear of the grinding wheel after the grinding performance is restored. In addition, since the grinding wheel is not excessively worn, the working time required for dressing can be reduced as compared with the case where the grinding wheel is worn by a predetermined amount regardless of the combination of the grinding wheel and the dresser board.

It is a perspective view of a grinding apparatus. It is a partial cross-sectional side view of a grinding unit and the like. It is a flow chart of the dressing method which concerns on this embodiment. This is an example of a graph showing the load according to this embodiment. This is an example of a graph showing the load according to the comparative example.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the grinding device 2. FIG. 2 is a partial cross-sectional side view of the first grinding unit 42 and the like. In FIG. 2, a part of the components is shown as a block diagram. The grinding device 2 is a device for grinding plate-shaped workpieces such as semiconductor wafers, package substrates, optical device substrates, and ceramic substrates.

The grinding device 2 has a substantially rectangular parallelepiped base 4 that supports or houses the components. A cassette mounting table 6 and a cassette mounting table 8 are fixed to the front end of the base 4. For example, a cassette 10 for accommodating a work piece after grinding is placed on the cassette mounting table 6, and a cassette 12 for accommodating a work piece before grinding is placed on the cassette mounting table 8.

However, a cassette containing a dresser board (detailed later) for dressing the grinding wheel may be placed on the cassette mounting table 8. A transfer robot 14 is provided in an area of the base 4 adjacent to the cassette mounting table 6 and the cassette mounting table 8. The transfer robot 14 carries out the work piece or the like from the cassette 12, and also carries the work piece or the like into the cassette 10.

A positioning table 16 having a plurality of positioning pins is provided on the right rear side of the transfer robot 14. The positioning table 16 adjusts the position of the workpiece or the like carried out from the transfer robot 14 by moving a plurality of positioning pins along a predetermined direction.

A spinner cleaning device 18 is provided on the left rear side of the transfer robot 14. The spinner cleaning device 18 cleans the work piece after grinding, for example, and then dries it. A loading arm 20 and an unloading arm 22 are provided behind the region between the positioning table 16 and the spinner cleaning device 18.

The loading arm 20 carries a work piece or the like from the positioning table 16 to the chuck table (holding table) 28 described later. Further, the unloading arm 22 carries the workpiece or the like from the chuck table 28 to the spinner cleaning device 18.

A disk-shaped turntable 24 is provided on the rear end side of the base 4 with respect to the loading arm 20 and the unloading arm 22. A drive mechanism (not shown) such as a motor is provided below the turntable 24, and the turntable 24 can rotate in both clockwise and counterclockwise directions.

A plurality of chuck tables 28 are provided on the turntable 24. For example, on the upper surface of the turntable 24, three chuck tables 28 are provided in a state of being separated by 120 degrees in the circumferential direction of the turntable 24.

By rotating the turntable 24, each chuck table 28 is divided into a loading / unloading region A accessible to the loading arm 20 and the unloading arm 22, a first grinding region B, and a second grinding region C, respectively. Positioned. Here, the chuck table 28 and the like will be described with reference to FIG.

Each chuck table 28 has a substantially disk shape and has a metal frame body 28a on the upper surface side. A flow path is provided in the frame body 28a, and one end of the flow path is connected to a suction source (not shown) such as an ejector.

The frame body 28a has a recess formed by a disk-shaped space on the upper surface side, and a substantially disk-shaped porous plate 28b is fixed to the recess. The porous plate 28b has a flat circular lower surface and a substantially conical upper surface.

The other end of the flow path of the frame body 28a is connected to the porous plate 28b. When the suction source is operated, a negative pressure is generated on the upper surface of the porous plate 28b, and the workpiece or the like is sucked and held on the upper surface. Therefore, the upper surface of the chuck table 28 functions as a holding surface 28c.

A disk-shaped table base 30 is connected to the lower surface side of the chuck table 28. A θ table 32 having a drive mechanism (not shown) such as a motor is connected to the lower surface side of the table base 30. By this drive mechanism, the turntable 24 is rotated around the rotation shaft 28d.

One fixed support member 34 and two movable support members 34a are provided on the lower surface side of the table base 30. In addition, in FIG. 2, one fixed support member 34 and one movable support member 34a are shown.

One fixed support member 34 and two movable support members 34a are connected to each other on the lower surface of the table base 30 in a state of being separated by 120 degrees in the circumferential direction of the table base 30, and support the chuck table 28 from below. ing.

The height of the upper end of the fixed support member 34 is fixed. On the other hand, the height of the upper end of the movable support member 34a can be moved in the vertical direction. By adjusting the heights of the upper ends of the two movable support members 34a, the rotating shaft 28d can be tilted by a predetermined angle with respect to the vertical direction.

The vertical direction is, for example, a direction parallel to the rotation axis 42e of the first grinding unit 42, which will be described later. A load measuring unit 36 is provided between the lower surface of the table base 30 and the upper end of the fixed support member 34, and between the lower surface of the table base 30 and the upper end of the movable support member 34a, respectively.

The load measuring unit 36 has, for example, a piezoelectric element (not shown) provided so as to come into contact with the table base 30. The piezoelectric element generates a voltage according to the applied force. The stress (that is, load) received by the chuck table 28 is converted into a voltage by the load measuring unit 36. By monitoring this voltage, the load applied to the chuck table 28 can be monitored.

A rectangular parallelepiped column 38 and a column 38a (see FIG. 1) are provided at the rear portion of the base 4. A grinding feed unit 40 is provided in each of the column 38 and the column 38a.

The grinding feed unit 40 has a pair of guide rails 40a (see FIG. 1) parallel to the height direction of the column 38. Each guide rail 40a is fixed to the front surface of the column 38. A moving plate 40b is slidably attached to each guide rail 40a.

A nut portion 40c is provided on the rear surface side of the moving plate 40b, and a ball screw 40d arranged parallel to the height direction of the column 38 is connected to the nut portion 40c in a rotatable manner.

A pulse motor 40e is connected to one end of the ball screw 40d. If the ball screw 40d is rotated by the pulse motor 40e, the moving plate 40b moves along the guide rail 40a.

A first grinding unit 42 is provided on the front side of the moving plate 40b on the column 38 side, and a second grinding unit 42a is provided on the front side of the moving plate 40b on the column 38a side (). (See FIG. 1). The first grinding unit 42 is, for example, a rough grinding unit, and the second grinding unit 42a is, for example, a finish grinding unit.

Each of the first grinding unit 42 and the second grinding unit 42a has a spindle motor 42b. One end of a cylindrical spindle 42c is connected to the spindle motor 42b. The upper surface side of the disk-shaped wheel mount 42d is fixed to the other end of the spindle 42c.

The upper surface side of the annular first grinding wheel 44 is mounted on the lower surface side of the wheel mount 42d of the first grinding unit 42, and the lower surface side of the wheel mount 42d of the second grinding unit 42a is the first. The upper surface side of the grinding wheel 44a of No. 2 is mounted.

For example, a plurality of first grinding wheels 46 each having a segment shape are mounted on the lower surface side of the first grinding wheel 44, and for example, a plurality of segment-shaped first grinding wheels 46 are mounted on the lower surface side of the second grinding wheel 44a. A second grinding wheel 46a is attached.

The first grinding wheel 46 is, for example, a rough grinding wheel, and the second grinding wheel 46a is, for example, a finishing grinding wheel having smaller abrasive grains than the rough grinding wheel. The region directly below the first grinding unit 42 corresponds to the above-mentioned first grinding region B, and the region directly below the second grinding unit 42a corresponds to the above-mentioned second grinding region C.

When the spindle motor 42b is driven, the first grinding wheel 44 and the second grinding wheel 44a rotate around the axis (that is, the rotating shaft 42e) of each spindle 42c. At this time, the first grinding wheel 46 and the second grinding wheel 46a also rotate around each rotation shaft 42e.

When dressing at least one of the first grinding wheel 46 and the second grinding wheel 46a, the dressing tool 11 is held by the holding surface 28c. The dressing tool 11 has a dresser board 11a. The dresser board 11a is, for example, a flat disk-shaped plate having a diameter of 150 mm and a thickness of about 1 mm.

The dresser board 11a is formed by using, for example, a mixed material in which abrasive grains such as white random (WA) and green carbon (GC) are mixed with a binder such as vitrified and resinoid. However, the binder and the abrasive grains constituting the dresser board 11a may be appropriately changed according to the material of the grinding wheel, the size of the abrasive grains, the degree of concentration, and the like.

Disc-shaped support plates 11b made of resin are provided substantially concentrically on the back surface side of the dresser board 11a, and the dresser board 11a and the support plate 11b are fixed by an adhesive or the like.

The support plate 11b has a thickness of about 1 mm. Further, the support plate 11b has a diameter (for example, 205 mm) larger than that of the dresser board 11a so that the entire dresser board 11a can be supported.

The diameter of the support plate 11b is substantially the same as the diameter of the porous plate 28b. When the back surface side of the support plate 11b is suction-held by the holding surface 28c due to negative pressure, the dressing tool 11 is held by the holding surface 28c.

Transfer robot 14, positioning table 16, loading arm 20, unloading arm 22, spinner cleaning device 18, turntable 24, chuck table 28, θ table 32, grinding feed unit 40, first grinding unit 42, second grinding The unit 42a and the like are controlled by the control unit 48.

The control unit 48 is composed of a computer including a processing device such as a CPU (Central Processing Unit) and a storage device such as a flash memory. By operating the processing device according to software such as a program stored in the storage device, the control unit 48 functions as a concrete means in which the software and the processing device (hardware resource) cooperate with each other.

The control unit 48 is also connected to each load measuring unit 36. The control unit 48 can monitor the load applied to the chuck table 28 by monitoring the voltage generated by each load measuring unit 36.

Next, a dressing method of the first grinding wheel 46 using the grinding device 2 will be described. FIG. 3 is a flow chart of the dressing method according to the present embodiment. First, an operator, an automatic transfer robot, or the like places the cassette 12 containing the dressing tool 11 on the cassette mounting table 8.

Then, the transfer robot 14, the positioning table 16, the loading arm 20, and the like are operated to hold the dressing tool 11 on the chuck table 28 located in the carry-in / carry-out area A of the turntable 24 (holding step (S10)).

At this time, the back surface side of the support plate 11b is held by the chuck table 28 so that the front surface side of the dresser board 11a is located upward. After the holding step (S10), the turntable 24 is rotated to move the chuck table 28 holding the dressing tool 11 to, for example, the first grinding region B.

Then, the chuck table 28 is rotated around the rotation shaft 28d at, for example, 40 rpm. Further, the first grinding wheel 44 is rotated in the same direction as the chuck table 28, for example, at 2000 rpm. The rotation speeds of the chuck table 28 and the first grinding wheel 44 are not limited to the above values.

In this state, from a position approximately 100 μm above the surface of the dresser board 11a, a predetermined speed (for example, for example) is used in the direction in which the first grinding unit 42 approaches the holding surface 28c of the chuck table 28 using the grinding feed unit 40. Grind and feed at 5 μm / s).

In the present embodiment, the first grinding unit 42 is grounded and fed while the load on the chuck table 28 is measured by the load measuring unit 36. For a while (for example, about 20 seconds) after the start of grinding feed, grinding feed is performed in a state where the first grinding wheel 46 is not in contact with the dresser board 11a (air cut step (S20)).

After the air cut step (S20), the first grinding wheel 46 is pressed against the surface side of the dresser board 11a to start dressing of the first grinding wheel 46 (dressing start step (S30)).

In the initial stage of dressing, the first grinding wheel 46, which is not sufficiently trued, comes into contact with the dresser board 11a, so that the contact area between the abrasive grains of the first grinding wheel 46 and the dresser board 11a is relatively small. ..

Therefore, in the initial stage of dressing, the amount of wear of the dresser board 11a is relatively small, and the load applied to the dresser board 11a and the chuck table 28 is also relatively low. However, as the first grinding wheel 46 is dressed, the contact area between the abrasive grains of the first grinding wheel 46 and the dresser board 11a gradually increases, and the load applied to the dresser board 11a and the chuck table 28 gradually increases. To increase.

FIG. 4 is an example of a graph showing the load according to the present embodiment. In FIG. 4, the horizontal axis represents the time (s) and the vertical axis represents the load (N) measured by the load measuring unit 36. In FIG. 4, the first grinding wheel 46 is in contact with the dresser board 11a at time T0.

As shown in FIG. 4, as time passes, when the first grinding wheel 46 is sufficiently dressed (that is, when the grinding performance of the first grinding wheel 46 is restored), the dresser board 11a per unit time The amount of wear becomes substantially constant. At this time, the fluctuation amount of the load applied to the dresser board 11a and the chuck table 28 for a predetermined period ΔT becomes a predetermined value D or less.

Therefore, in the dressing method of the present embodiment, the grinding feed by the first grinding unit 42 is stopped when the fluctuation amount of the load of the predetermined period ΔT becomes a predetermined value D or less (grinding feed stop step (S40)).

The amount of fluctuation of the load means, for example, the magnitude of the maximum deviation from the average value of the load of the predetermined period ΔT from the time T to the time (T−ΔT). The predetermined value D, which is a criterion for determining the stop of the grinding feed, is set to, for example, a value of 3N or more and 5N or less. In this embodiment, the predetermined value D is set to 3N.

However, this predetermined value D is not limited to 3N or more and 5N or less, and may be appropriately set according to the combination of the first grinding wheel 46 and the dresser board 11a. Further, the predetermined value D may be predetermined before the holding step (S10) or after the dressing start step (S30).

Further, the predetermined period ΔT in this embodiment is, for example, 3 s. That is, in the present embodiment, after the start of dressing, the grinding feed is stopped when the maximum deviation amount from the average value of the load for 3 s is 3 N or less. However, the predetermined period ΔT is not limited to 3s.

In the example shown in FIG. 4, the average value of the load for a predetermined period ΔT from the time _{T 1} to time _(T 1 _-ΔT), is about 7N. On the other hand, the load deviates most from the average value in time (T _{1 −} ΔT), and the amount of fluctuation of the load is about 6N. Therefore, at the time of time T _1, it does not stop the grinding feed.

On the other hand, the average value of the load of the predetermined period ΔT from the time T ₂ to the time (T _2- ΔT) is about 11N, and the fluctuation amount of the load is 3N or less. Therefore, the control unit 48 stops the grinding feed according to the first grinding unit 42 at time T _2.

In this way, when the grinding performance of the first grinding wheel 46 is restored and the fluctuation amount of the load of ΔT for a predetermined period becomes equal to or less than the predetermined value D, the grinding feed is stopped, so that after the grinding performance is restored. Excessive wear of the first grinding wheel 46 can be prevented. The amount of wear of the first grinding wheel 46 during the period from time T ₀ to time T ₂ was 40 μm.

Further, in the present embodiment, since the first grinding wheel 46 is not excessively worn, the first grinding wheel 46 is worn by a certain amount (for example, 100 μm) regardless of the combination of the first grinding wheel 46 and the dresser board 11a. The working time required for dressing can be reduced as compared with the case of making the dressing.

By the way, during dressing, the rotation speed of the grinding wheel is substantially constant at 2000 rpm, and the current value of the motor that rotates the grinding wheel is also substantially constant at 4 A. Therefore, it is difficult to grasp the dressing state of the first grinding wheel 46 by using the rotation speed, the current value, and the like. On the other hand, in the present embodiment, by measuring the load, the dressing status can be grasped in more detail as compared with the case of monitoring the current value of the motor.

After the grinding feed stop step (S40), the load gradually decreases. After the load becomes substantially zero, the rotation of the chuck table 28 and the first grinding wheel 44 is stopped. Then, the turntable 24 is rotated to return the chuck table 28 holding the dressing tool 11 to the carry-in / carry-out area A. After that, the dressing tool 11 is carried out to, for example, the cassette 12 by using the unloading arm 22 or the like.

Next, a comparative example will be described. FIG. 5 is an example of a graph showing the load according to the comparative example. In the comparative example, in the same manner as in the above-described embodiment, after measuring the load, a fixed amount of the first grinding wheel 46 is applied during the period from time T ₀ to time T ₃ (time after time T ₂ ). 100 μm) Grind.

Also in this comparative example, the amount of fluctuation of the load in the predetermined period ΔT from the time T ₂ to the time (T _2- ΔT) is equal to or less than the predetermined value D. However, since the first grinding wheel 46 is set to be ground by a constant amount, the first grinding wheel 46 is also ground during the time T ₂ to the time T ₃ .

Therefore, in the comparative example, the first grinding wheel 46 is excessively worn. In addition, the work time required for dressing becomes long. On the other hand, the present embodiment is advantageous in that excessive wear of the first grinding wheel 46 in dressing can be prevented and the working time required for dressing can be shortened.

In addition, the structure, method, etc. according to the above-described embodiment can be appropriately modified and implemented as long as the scope of the object of the present invention is not deviated. For example, the second grinding wheel 46a of the second grinding unit 42a can be dressed by the dressing method of the above-described embodiment.

The dressing tool 11 for the second grinding wheel 46a includes, for example, a disk-shaped dresser board 11a having a diameter of 80 mm and a thickness of about 1 mm, and a disk-shaped support plate having a diameter of 205 mm and a thickness of about 1 mm. It is composed of 11b.

The dressing tool 11 for the second grinding wheel 46a is carried into the chuck table 28, the chuck table 28 is rotated at, for example, 40 rpm, and the second grinding wheel 44a is rotated in the same direction as the chuck table 28, for example, at 2000 rpm. The rotation speeds of the chuck table 28 and the second grinding wheel 44a are not limited to the above values.

Then, if the grinding feed is performed at a predetermined speed (for example, 1 μm / s), the second grinding wheel 46a can be dressed. Further, the dressing tool 11 may be held by each of the two chuck tables 28, and the first grinding wheel 46 and the second grinding wheel 46a may be dressed in parallel.

2 Grinding device 4 Base 6,8 Cassette mounting table 10,12 Cassette 11 Dressing tool 11a Dresser board 11b Support plate 14 Transfer robot 16 Positioning table 18 Spinner cleaning device 20 Loading arm 22 Unloading arm 24 Turntable 28 Chuck table (holding) table)
28a Frame 28b Porous plate 28c Holding surface 28d Rotating shaft 30 Table base 32 θ Table 34 Fixed support member 34a Movable support member 36 Load measurement unit 38, 38a Column 40 Grinding feed unit 40a Guide rail 40b Moving plate 40c Nut part 40d Ball screw 40e Pulse motor 42 1st grinding unit 42a 2nd grinding unit 42b Spindle motor 42c Spindle 42d Wheel mount 42e Rotating shaft 44 1st grinding wheel 44a 2nd grinding wheel 46 1st grinding wheel 46a 2nd grinding Grinding stone 48 Control unit A Carry-in / carry-out area B First grinding area C Second grinding area

Claims (1)

A dressing method for dressing a grinding wheel provided on the lower surface side of an annular grinding wheel.
A holding step that holds the dresser board on the holding surface of the holding table,
While rotating the grinding wheel around a predetermined rotation axis, the grinding wheel is ground and fed in a direction approaching the holding table, and the grinding wheel is pressed against the dresser board held by the holding table. With the dressing start step of starting the dressing of the grinding wheel,
A grinding feed stop step in which the load on the holding table is measured by a load measuring unit and the grinding feed is stopped when the fluctuation amount of the load for a predetermined period after the dressing start step becomes equal to or less than a predetermined value. A dressing method characterized by comprising.