JP7517875B2 - Chuck table and processing device - Google Patents

Description

The present invention relates to a chuck table and a processing device.

In a processing apparatus including a grinding device that uses a grinding wheel to grind a workpiece held on the holding surface of a chuck table, the chuck table is rotated around the center of the chuck table as an axis, and processing is performed by contacting the workpiece with a processing tool such as a grinding wheel or a polishing pad. During processing of the workpiece, the thickness of the workpiece is measured.
The thickness of the workpiece is calculated by calculating the difference between the height of the holding surface and the height of the upper surface of the workpiece held on the holding surface. Therefore, in measuring the thickness of the workpiece, it is necessary to measure the height of the holding surface and the height of the upper surface of the workpiece, and as disclosed in Patent Document 1, a thickness measuring means equipped with two measuring instruments, a holding surface height gauge and an upper surface height gauge, is used.

The chuck table 9 shown in FIG. 14 as an example of a conventional chuck table has a holding surface 90 on which the workpiece 14 is held, and an annular measuring surface 91 on which a holding surface height gauge (not shown) is positioned to measure the height of the holding surface 90. When measuring the thickness of the workpiece 14, while the workpiece 14 is held on the holding surface 90, a top surface height gauge (not shown) is positioned on the top surface 140 of the workpiece 14, and a holding surface height gauge (not shown) is positioned on the measuring surface 91.

JP 2020-049557 A

Chuck tables having an annular measuring surface on the outside of the holding surface for holding the workpiece as described above are large and heavy, which creates a workload when attaching the chuck table to the processing device or when replacing the chuck table.
Therefore, in the case of a chuck table disposed in a processing device, there is a problem in that it is necessary to facilitate operations such as attachment and replacement of the chuck table.

The present invention is a chuck table used in a processing device that includes at least a chuck table having a holding surface for holding a workpiece, a table rotation unit that rotates the chuck table around the center of the chuck table, a processing means for processing the workpiece held on the holding surface, a top surface height measuring device that measures in a non-contact manner the top surface height of the workpiece rotated by the table rotation unit, and a thickness calculation unit that calculates the thickness of the workpiece using the value measured by the top surface height measuring device, wherein the chuck table includes a base and a holding member arranged on the top surface of the base, the holding surface is the top surface of the holding member and is located higher than the top surface of the base, and with the top surface height measuring device positioned above the holding surface, the chuck table is rotated using the table rotation unit to provide a measurement surface that is formed on the measurement orbit of the top surface height measuring device that moves relative to the chuck table, and at a position other than the holding surface, and is flush with the holding surface .
It is desirable that the chuck table has a plurality of holding surfaces arranged on a measurement track along which the upper surface height measuring device measures.
It is desirable that the above-mentioned chuck table comprises a sub-chuck table having the measurement surface and the holding surface, a base having a connecting surface that connects the sub-chuck table, an opening formed in the connecting surface of the base, and a communicating passage formed in the connected surface of the sub-chuck table that connects the opening to the holding surface.
The present invention is a processing apparatus comprising a holding means to which the chuck table is attached, which holds a workpiece on the holding surface and rotates around the center of the holding surface as an axis , a thickness measuring means for measuring the thickness of the workpiece, and a processing means for processing the workpiece to a predetermined thickness, the thickness measuring means comprising a top surface height measuring device for non-contact measuring the top surface height and the measured surface height of the workpiece held on the holding surface, and a thickness calculation unit for calculating the difference between the top surface height of the workpiece measured on the measurement orbit of the top surface height measuring device by rotation of the holding means and the height of the measured surface as the thickness of the workpiece.

Since the chuck table of the present invention does not require an annular measuring surface, the chuck table can be made smaller and lighter.
In addition, in a configuration in which the sub-chuck table is detachably disposed on the base, the sub-chuck table can be replaced on the base, making it possible to reduce the weight. Furthermore, since the sub-chuck table is replaceable, the size can be easily changed, and the number of workpieces that can be held can also be changed.

FIG. 2 is a perspective view showing the entire processing device. FIG. FIG. 11 is a plan view showing a rotation trajectory of a holding member when a chuck table rotates. FIG. FIG. FIG. 11 is a plan view showing a rotation trajectory of a holding member when a chuck table rotates. FIG. FIG. FIG. 11 is a plan view showing a rotation trajectory of a holding member when a chuck table rotates. FIG. FIG. 2 is a perspective view of a second chuck table. FIG. 1A is a perspective view showing a base plate with its front surface facing upward, and FIG. 1B is a perspective view showing a base plate with its coupled surface facing upward. FIG. 2 is a perspective view showing a chuck table having an annular measuring surface.

1 is a processing apparatus that grinds a workpiece 14 held on a chuck table 2 using a processing means 3. The configuration of the processing apparatus 1 will be described below.
As shown in FIG. 1, the processing device 1 includes a base 10 extending in the Y-axis direction, and a column 11 standing on the +Y-direction side of the base 10 .

A processing feed means 4 that supports the processing means 3 so that it can be raised and lowered is disposed on the side surface on the -Y direction side of the column 11. The processing means 3 is a grinding means that includes, for example, a spindle 30 having a rotation axis 35 in the Z-axis direction, a housing 31 that rotatably supports the spindle 30, a spindle motor 32 that rotates and drives the spindle 30 around the rotation axis 35, a mount 33 connected to the lower end of the spindle 30, and a grinding wheel 34 that is detachably attached to the lower surface of the mount 33.

The grinding wheel 34 comprises a wheel base 341 and a plurality of grinding stones 340, each of which is substantially rectangular and arranged in a ring shape on the underside of the wheel base 341. The underside of the grinding stone 340 forms a grinding surface 342 that comes into contact with the workpiece 14.

By rotating the spindle 30 using the spindle motor 32, the mount 33 connected to the spindle 30 and the grinding wheel 34 attached to the underside of the mount 33 rotate together.

The processing feed means 4 includes a ball screw 40 having a rotating shaft 45 in the Z-axis direction, a pair of guide rails 41 arranged parallel to the ball screw 40, a Z-axis motor 42 that rotates the ball screw 40 around the rotating shaft 45, a lift plate 43 whose internal nut is screwed onto the ball screw 40 and whose side is in sliding contact with the guide rail 41, and a holder 44 connected to the lift plate 43 and supporting the processing means 3.

When the ball screw 40 is driven by the Z-axis motor 42 and rotates around the rotation shaft 45, the lift plate 43 moves up and down in the Z-axis direction while being guided by the guide rail 41, and the grinding wheel 34 of the processing means 3 held by the holder 44 moves in the Z-axis direction.

The chuck table 2 is disposed on the base 10. An internal base 100 is disposed inside the base 10, and a horizontal moving means 5 for moving the chuck table 2 in the horizontal direction (Y-axis direction) is disposed on the internal base 100.
The horizontal movement means 5 includes a ball screw 50 having a rotation axis 55 in the Y-axis direction, a pair of guide rails 51 arranged parallel to the ball screw 50, a Y-axis motor 52 connected to the ball screw 50 and rotating the ball screw 50 around the rotation axis 55, and a movable plate 53 whose bottom nut is screwed onto the ball screw 50 and moves along the guide rails 51 in the Y-axis direction.
When the ball screw 50 is driven by the Y-axis motor 52 and rotates about the rotation shaft 55, the movable plate 53 is guided by the guide rail 51 and moves in the Y-axis direction.

The table rotating unit 25 is disposed on the movable plate 53. The table rotating unit 25 includes a rotating member 250 that rotatably supports the chuck table 2, and an annular member 251 disposed around the rotating member 250. The annular member 251 supports the rotating member 250 in a rotatable state.
For example, three (two are shown in FIG. 1 ) through holes 256 are formed at equally spaced positions on the same circumference of the annular member 251, and three (two are shown in FIG. 1 ) support pillars 257 supporting the annular member 251 are erected on the movable plate 53. Each of the through holes 256 is penetrated by a corresponding one of the support pillars 257, which is fixed onto the movable plate 53. Each of the support pillars 257 has, for example, an extension mechanism (not shown), and the inclination of the chuck table 2 is adjusted by each of the support pillars 257 appropriately extending and contracting in the Z-axis direction.

The rotating member 250 is connected to, for example, a motor (not shown). By operating the motor to rotate the rotating member 250, it is possible to rotate the chuck table 2 around its center 2000 as an axis.

In addition, the movable plate 53 is moved in the Y-axis direction by the horizontal movement means 5, so that the table rotation unit 25 and the chuck table 2 move in the Y-axis direction together with the movable plate 53.

A cover 27 and a bellows 28 connected to the cover 27 so as to be freely stretchable are disposed around the chuck table 2. For example, when the chuck table 2 moves in the Y-axis direction, the cover 27 moves in the Y-axis direction together with the chuck table 2, causing the bellows 28 to stretch.

On the −X direction side of the base 10 , there is disposed an upper surface height measuring device 6 for non-contactly measuring the height of an upper surface 140 of the workpiece 14 rotated by the table rotating section 25 .
The upper surface height measuring device 6 is, for example, a laser type height measuring device that projects a laser beam and measures the reflected light to measure the height of the portion onto which the laser beam is projected.

As shown in Fig. 2, the chuck table 2 includes a substantially disk-shaped base 20 and three substantially rectangular parallelepiped holding members 21 disposed on an upper surface 200 of the base 20. Fig. 3 shows a plan view of the chuck table 2. All of the three holding members 21 are arranged, for example, parallel to the Y-axis direction, and the middle one of the three is disposed slightly shifted toward the radial rear side of the base 20 (the +Y direction side).
The upper surface of the holding member 21 is a holding surface 210 for holding the plate-shaped workpiece 14. The workpiece 14 can be held on each of the three holding surfaces 210.

A convex portion 23 is formed on the base 20 of the chuck table 2 at a position that is not on the holding surface 210. The convex portion 23 is disposed on the radial front side (−Y direction side) of the upper surface 200 of the base 20, for example.
4 shows a diagram in which the positions of the workpiece 14 when the chuck table 2 is rotated about the center 2000 of the chuck table 2 with the workpiece 14 held on the holding surface 210 of the holding member 21 are drawn and superimposed for every 30 degrees of rotation of the chuck table 2. The convex portion 23 is provided at a position inside a first maximum locus 291 obtained by connecting in a circle the outermost parts of the locus of the workpiece 14 drawn by rotating the chuck table 2 about its center 2000 using the table rotation part 25 with the workpiece 14 held on the holding surface 210, and outside a first minimum locus 281 obtained by connecting in a circle the innermost parts.

The upper surface of the convex portion 23 is a measurement surface 230 whose height is measured by the upper surface height measuring device 6. The height of the measurement surface 230 and the height of the holding surface 210 are, for example, the same, and the height of the holding surface 210 can be recognized by measuring the height of the measurement surface 230.
Alternatively, the holding surface 210 and the measurement surface 230 may not be formed flush with each other, and a predetermined difference may be provided between the height of the measurement surface 230 and the height of the holding surface 210. In this configuration, the measurement surface 230 is formed lower than the upper surface of the machined workpiece 14 held on the holding surface 210. In this configuration, the height of the measurement surface 230 is measured, and the height of the holding surface 210 can be recognized by appropriately adding or subtracting a predetermined difference to the measured height of the measurement surface 230.

Figure 4 also shows a first measurement orbit 241, which is one of the orbits that pass through the measurement surface 230 and the three holding surfaces 210. The first measurement orbit 241 is the movement path of the top surface height measuring device 6 that moves relative to the chuck table 2 when measuring the thickness of the workpiece 14. With the top surface height measuring device 6 positioned above a point on the first measurement orbit 241, the table rotation unit 25 is used to rotate the chuck table 2, causing the top surface height measuring device 6 to pass over the first measurement orbit 241.

2, the base 20 will be described. A recess 22 recessed toward the -Z direction side is formed on the radially outermost side of the base 20. A plurality of screw holes 223 are formed on the upper surface of the recess 22.
The base 20 is attached to a chuck base (not shown) provided at the upper end of the rotating member 250 shown in Fig. 1 by screwing it with a screw (not shown) that corresponds to the screw hole 223. In the processing device 1, the base 20 of the chuck table 2 is attached to the chuck base, whereby the table rotating part 25 and the chuck table 2 are integrated to form a holding means. By removing the screw, the base 20 can be attached and detached to the chuck base.

The holding surface 210 of each holding member 21 is connected to a suction source (not shown). When the workpiece 14 is placed on the holding surface 210, the suction source is operated and the suction force generated is transmitted to the holding surface 210, so that the workpiece 14 can be sucked and held on the holding surface 210.

1, a thickness calculation unit 7 is connected to the top surface height measuring device 6. The thickness calculation unit 7 has a computer equipped with a CPU, memory, etc., and can calculate the thickness of the workpiece 14 by calculating the difference between the height of the top surface 140 of the workpiece 14 measured by the top surface height measuring device 6 and the height of the measurement surface 230 in the thickness calculation unit 7.
The upper surface height measuring device 6 and the thickness calculating section 7 constitute a thickness measuring means for measuring the thickness of the workpiece 14 .

The operation of the processing device 1 when the processing device 1 is used to grind the workpiece 14 while calculating the thickness of the workpiece 14 will be described.
When grinding the workpieces 14 using the processing device 1, first, three workpieces 14 are placed on the holding surface 210 of the chuck table 2. Then, a suction source (not shown) connected to the chuck table 2 is operated to transmit the generated suction force to the holding surface 210. As a result, the three workpieces 14 are suction-held on the holding surface 210.

With the workpiece 14 held by suction on the holding surface 210, the horizontal movement means 5 is used to move the chuck table 2 an appropriate distance in the +Y direction. As a result, the chuck table 2 is positioned below the processing means 3, and the top surface height measuring device 6 is positioned above the first measurement orbit 241 shown in FIG. 2.

Next, the table rotating unit 25 is used to rotate the chuck table 2 to rotate the workpiece 14 held on the holding surface 210, and the spindle motor 32 is used to rotate the grinding wheel 340 around the rotating shaft 35 as its axis.
When the chuck table 2 rotates with the top surface height measuring device 6 positioned on the first measurement orbit 241, the top surface height measuring device 6 is repeatedly positioned on the top surface 140 of the workpiece 14 on the first measurement orbit 241, on the top surface 200 of the base 20, and on the measurement surface 230. When the top surface height measuring device 6 is positioned on the top surface 140 of the workpiece 14, the height of the top surface 140 of the workpiece 14 is measured. When the top surface height measuring device 6 is positioned on the measurement surface 230, the height of the measurement surface 230 is measured, and the height of the holding surface 210 is recognized. Then, the measured information on the height of the top surface 140 of the workpiece 14 and the height information on the measurement surface 230 are each transmitted to the thickness calculation unit 7, and the difference between the two is calculated in the thickness calculation unit 7. As a result, the thickness of the workpiece 14 is calculated.

With the workpiece 14 rotating and the grinding wheel 340 rotating about the rotation shaft 35, the processing means 3 is lowered in the -Z direction using the processing feed means 4. By lowering the grinding wheel 340 in the -Z direction, the grinding surface 342 of the grinding wheel 340 comes into contact with the upper surface 140 of the workpiece 14.
With the grinding surface 342 in contact with the upper surface 140 of the workpiece 14, the grinding wheel 340 is further lowered in the -Z direction, thereby grinding the workpiece 14.
As the workpiece 14 is ground, the thickness of the workpiece 14 calculated by the thickness calculation unit 7 decreases.

When the workpiece 14 has been ground to a predetermined thickness, the grinding process of the workpiece 14 is terminated, and the processing means 3 is moved in the +Z direction using the processing feed means 4 to move the grinding wheel 340 away from the upper surface 140 of the workpiece 14, and then the workpiece 14 is removed from the holding surface 210 of the chuck table 2.

The conventional chuck table 9 shown in FIG. 14 has an annular measuring surface 91 on which a measuring device is positioned during thickness measurement, whereas the chuck table 2 shown in FIG. 2 does not have such an annular measuring surface. Therefore, the chuck table 2 can be made smaller and lighter.

The positions and the number of the holding members 21 disposed on the base 20 of the chuck table 2 are not limited to those described above.
For example, as shown in Fig. 5, three holding members 21 may be arranged on the upper surface 200 of the base 20 in parallel to the X-axis direction with the positions of the respective short sides in the Y-axis direction coinciding with each other. Fig. 6 shows a plan view of the chuck table 2 in this case. Fig. 7 shows a diagram in which the positions of the workpiece 14 held by the chuck table 2 are drawn and superimposed on each other every 45 degrees of rotation of the chuck table 2 when the chuck table 2 is rotated about the center 2000 of the base 20 of the chuck table 2 as an axis.
In this configuration, the convex portion 23 is located inside the second maximum locus 292, which is formed by connecting the outermost parts of the rotational locus of the workpiece 14 in a circular shape, and outside the second minimum locus 282, which is formed by connecting the innermost parts in a circular shape.
A second measurement orbit 242 is defined as one of the orbits passing through each holding surface 210 of the three holding members 21 and the upper surface 200 of the base 20, and when measuring the thickness of the workpiece 14, the upper surface height measuring device 6 is positioned on the second measurement orbit 242.

Also, as shown in FIG. 8, four holding members 21 may be arranged on the base 20 of the chuck table 2. In this case, the measurement surface 230 is provided inside the maximum trajectory of the workpiece 14 and outside the minimum trajectory when the chuck table 2 rotates around its center 2000 with the workpiece 14 held on the holding surface 210 of each holding member 21. A third measurement orbit 243 is defined as one of the orbits passing through the holding surface 210 and the measurement surface 230 of each of the four holding members 21, and when measuring the thickness of the workpiece 14, the top surface height measuring device 6 is positioned on the third measurement orbit 243. In this configuration, a maximum of four workpieces 14 can be simultaneously ground by holding the workpieces 14 on each of the holding surfaces 210 of the four holding members 21.

Also, as shown in FIG. 9, a single holding member 21 may be disposed on the base 20 of the chuck table 2. FIG. 10 shows a diagram in which the position of the workpiece 14 when the chuck table 2 rotates around the center 2000 of the base 20 of the chuck table 2 with the workpiece 14 held by the holding member 21 is drawn and superimposed every time the chuck table 2 rotates 45 degrees. In this configuration, the convex portion 23 is provided inside the fourth maximum locus 294 obtained by connecting the outermost parts of the rotation locus of the workpiece 14 in a circle and outside the fourth minimum locus 284 obtained by connecting the innermost parts in a circle. A fourth measurement orbit 244 is defined as one of the orbits passing through the holding surface 210 of the holding member 21 and the upper surface 200 of the base 20, and when measuring the thickness of the workpiece 14, the upper surface height measuring device 6 is positioned on the fourth measurement orbit 244.

In addition, instead of providing a convex portion 23 on the upper surface 200 of the base 20 and using the upper surface of the convex portion 23 as the measurement surface 230 as described above, the upper surface 200 of the base 20 may be used as the measurement surface. In this configuration, for example, the difference between the height of the upper surface 200 of the base 20 and the height of the holding surface 210 is calculated in advance, and the height of the holding surface 210 can be recognized by adding or subtracting this difference from the measured height of the upper surface 200 of the base 20.

The holding member disposed on the upper surface 200 of the base 20 is not limited to the plate-shaped holding member 21. For example, when grinding a disk-shaped workpiece, the grinding can be performed efficiently by disposing a disk-shaped holding member instead of the holding member 21 on the upper surface 200 of the base 20.

The processing apparatus 1 may be provided with a second chuck table 8 as shown in Fig. 11 instead of the chuck table 2. The second chuck table 8 includes a substantially disk-shaped second base 84 and a sub-chuck table 80 detachably connected to the second base 84.
As shown in FIG. 12, the second base 84 has a connection surface 840 for connecting the sub-chuck table 80, and an opening 841 is formed in the center of the connection surface 840.
Further, a recess 842 recessed toward the -Z direction side is formed on the radially outermost peripheral side of the second base 84, and a plurality of screw holes 843 are formed on the upper surface of the recess 842. The second base 84 is attached, for example, by being screwed to the above-mentioned chuck base using screws (not shown) that correspond to the screw holes 843. By removing the screws, the second base 84 can be attached and detached to the chuck base.

As shown in FIG. 13(a), the sub-chuck table 80 includes a base plate 82 formed in a substantially square shape, and three substantially rectangular second holding members 81 arranged on a surface 820 of the base plate 82. All three second holding members 81 are arranged, for example, parallel to the Y axis, and the middle one of the three is arranged slightly shifted toward the radial rear side (+Y direction side) of the second base 84. The upper surface of the second holding member 81 is a holding surface 810 on which the workpiece 14 is held.

Further, a convex portion 83 is formed on the surface 820 of the base plate 82. The convex portion 83 is provided inside the maximum locus and outside the minimum locus described by the second holding member 81 when the chuck table 2 rotates about its center 2000. The upper surface of the convex portion 83 is a measurement surface 830.
In this configuration, a fifth measurement orbit 245 is defined as one of the orbits that passes above the holding surfaces 810 of each of the three second holding members 81 and above the measurement surface 830, and when measuring the thickness of the workpiece 14, the top surface height measuring device 6 is positioned on the fifth measurement orbit 245.

For example, the holding surface 810 and the measurement surface 830 are formed flush with each other, and it is possible to recognize the height of the holding surface 810 by measuring the height of the measurement surface 830 .
Alternatively, the holding surface 810 and the measurement surface 830 may not be formed flush with each other, and a predetermined difference may be provided between the height of the measurement surface 830 and the height of the holding surface 810. In this configuration, the height of the measurement surface 830 is measured, and the height of the holding surface 810 can be recognized by adding or subtracting the predetermined difference to the measured height of the measurement surface 830.

13B shows a state in which a connected surface 821, which is the opposite surface of the front surface 820 of the base plate 82, is oriented in the +Z direction. A communication passage 822 that connects the opening 841 and the holding surface 810 is formed in the connected surface 821 of the base plate 82. The communication passage 822 has, for example, two rectangular portions formed next to each other as shown in the figure and a circular portion formed so as to straddle the two rectangular portions.
When connecting the sub-chuck table 80 to the second base 84, the surface 820 of the sub-chuck table 80 is faced toward the +Z direction as shown in FIG. 13(a), and the sub-chuck table 80 is placed on the connecting surface 840 of the second base 84 so that the central portion 8220 of the communicating passage 822 shown in FIG. 13(b) coincides with the opening 841 of the second base 84 shown in FIG. 12.
Then, with the sub-chuck table 80 placed on the second base 84, suction means (not shown) connected to the opening 841 of the connecting surface 840 is operated. The suction force generated is transmitted to the communicating passage 822, connecting the sub-chuck table 80 to the second base 84. The suction force is also transmitted to the holding surface 810 of the second holding member 81 disposed on the sub-chuck table 80. Therefore, by placing the workpiece 14 on the holding surface 810 in this state, the workpiece 14 can be suction-held on the holding surface 810.
Note that the connecting surface 840 may be formed with a groove (not shown) that extends in the radial direction through the opening 841. When the groove is formed, the suction force can be more efficiently transmitted from the opening 841 to the connected surface 821 of the sub-chuck table 80, making it possible to easily connect the sub-chuck table 80 to the second base 84.

Like chuck table 2, second chuck table 8 does not have an annular measuring surface on which top surface height measuring device 6 is positioned, so it can be made smaller, allowing the processing apparatus itself to be made smaller.
Furthermore, whereas conventionally the base of the chuck table was changed according to the size and number of the workpieces 14, the second chuck table 8 changes the sub-chuck table 80 according to the size and number of the workpieces 14 to be ground. Therefore, it is possible to easily change it, which is preferable.

The holding member arranged on the sub-chuck table 80 is not limited to the plate-shaped second holding member 81. For example, when grinding a disk-shaped workpiece, the grinding can be performed efficiently by arranging a disk-shaped holding member.

Furthermore, the processing device 1 is not limited to a grinding device equipped with the grinding wheel 34 shown in FIG. 1, but may be, for example, a polishing device equipped with a polishing pad (not shown) instead of the grinding wheel 34.

1: Processing device 10: Base 100: Internal base 2: Chuck table 20: Base 200: Upper surface of base 21: Holding member 210: Holding surface 22: Concave portion 223: Screw hole 23: Convex portion 230: Measurement surface 25: Table rotation portion 250: Rotating member 251: Annular member 256: Through hole 257: Support column 3: Processing means 30: Spindle 31: Spindle housing 32: Spindle motor 33: Mount 34: Grinding wheel 340: Grinding stone 341: Wheel base 342: Grinding surface 35: Rotating shaft 4: Processing feed means 40: Ball screw 41: Guide rail 42: Z-axis motor 43: Lift plate 44: Holder 45: Rotating shaft 5: Horizontal movement means 50: Ball screw 51: Guide rail 52: Y-axis motor 53: Movable plate 55: Rotation shaft 6: Top surface height measuring device 7: Thickness calculation section 8: Second chuck table 80: Sub-chuck table 81: Second holding member 810: Holding surface 82: Base plate 820: Surface of base plate 821: Connected surface 822: Communication passage 83: Convex portion 830: Measurement surface 84: Second base 840: Top surface of second base 841: Opening 842: Convex portion 843: Screw hole 241: First measurement orbit 242: Second measurement orbit 243: Third measurement orbit 244: Fourth measurement orbit 245: Fifth measurement orbit 281: First minimum locus 282: Second minimum locus 284: Fourth minimum locus 291: First maximum locus 292: Second maximum locus 294: Fourth maximum locus 9: Chuck table 90: Holding surface 91: Measurement surface

Claims (4)

a chuck table having a holding surface for holding a workpiece;
a table rotating unit that rotates the chuck table about its center;
a processing means for processing a workpiece held on the holding surface;
a top surface height measuring device that measures the height of the top surface of the workpiece rotated by the table rotating part in a non-contact manner;
a thickness calculation unit that calculates a thickness of a workpiece using a value measured by the upper surface height measuring device,
The chuck table includes a base and a holding member disposed on an upper surface of the base.
the holding surface is an upper surface of the holding member and is located at a position higher than an upper surface of the base,
With the top surface height measuring device positioned above the holding surface, the chuck table is rotated using the table rotation unit to move the top surface height measuring device relative to the chuck table, and the chuck table has a measurement surface that is formed on a measurement orbit of the top surface height measuring device at a position other than the holding surface and is flush with the holding surface . 2. The chuck table according to claim 1, wherein a plurality of said holding surfaces are arranged on a measurement track measured by said upper surface height measuring device. a sub-chuck table including the measurement surface and the holding surface;
a base having a connection surface for connecting the sub-chuck table;
an opening formed in the coupling surface of the base;
2. The chuck table according to claim 1, further comprising a communication passage formed in the connected surface of the sub-chuck table, the communication passage connecting the opening and the holding surface. a holding means having the chuck table according to claim 1 attached thereto, holding a workpiece on said holding surface and rotating about a center of said holding surface ;
A thickness measuring means for measuring the thickness of the workpiece;
A processing means for processing the workpiece to a predetermined thickness;
A processing apparatus comprising:
The thickness measuring means is
A processing apparatus comprising: a top surface height measuring device that measures the top surface height and the measurement surface height of a workpiece held on the holding surface in a non-contact manner; and a thickness calculation unit that calculates the difference between the top surface height of the workpiece measured on the measurement orbit of the top surface height measuring device by rotating the holding means and the height of the measurement surface as the thickness of the workpiece.

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