JP7628441B2 - Chuck Table Mechanism - Google Patents

Description

The present invention relates to a chuck table mechanism that includes a chuck table that holds a workpiece and a table base that detachably supports the underside of the chuck table.

A wafer with multiple ICs, LSIs, and other devices formed on its surface, partitioned along planned dividing lines, has its back surface ground by a grinding device to form it to the desired thickness, and is then divided into individual device chips by processing equipment such as a laser processing device or a cutting device, for use in electrical devices such as mobile phones and personal computers.

The processing device is equipped with a holding table that holds the wafer by suction, and processes the wafer held on the holding table into the desired shape using various processing means such as grinding means, laser irradiation means, and cutting means.

In addition, there are multiple types of wafer diameters, such as 5 inches, 6 inches, and 8 inches, and chuck tables corresponding to the wafer sizes are prepared and replaced appropriately depending on the wafer size (see, for example, Patent Document 1).

Patent No. 3424052

However, the chuck table is heavy (10-30 kg), and it takes time for the worker to pick up the chuck table, place it on the table base, and accurately align the table base and chuck table to the desired positional relationship, making it difficult to attach the chuck table to the table base.

The present invention was developed in consideration of the above-mentioned facts, and its main technical objective is to provide a chuck table mechanism that allows the chuck table to be easily attached to the table base even if the chuck table is heavy.

In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a chuck table having a holding surface for holding a workpiece and a lower surface opposite to the holding surface, and a table base for detachably supporting the lower surface of the chuck table, the table base having a support surface for supporting the lower surface of the chuck table, a central suction hole formed in the center of the support surface, and an underside holding suction hole formed in the support surface for suction-holding the underside of the chuck table, the support surface of the table base having a first magnet embedded in a first region and a second magnet embedded in a second region spaced from the first region, The underside of the chuck table is provided with a third magnet embedded in a third region corresponding to the first region and attracted to the first magnet, and a fourth magnet embedded in a fourth region corresponding to the second region and attracted to the second magnet, and a compressed air supplying means is provided for supplying compressed air to the underside holding suction hole when the chuck table is attached to the support surface of the table base, to form an air layer between the underside of the chuck table and the support surface of the table base , and the first region is an area in which the first magnet is embedded, the first magnet being formed in a ring shape surrounding the central suction hole .

The chuck table mechanism of the present invention includes a chuck table having a holding surface for holding a workpiece and a lower surface opposite to the holding surface, and a table base for detachably supporting the lower surface of the chuck table, the table base including a support surface for supporting the lower surface of the chuck table, a central suction hole formed in the center of the support surface, and an underside holding suction hole formed in the support surface for suction-holding the underside of the chuck table, the support surface of the table base including a first magnet embedded in a first region and a second magnet embedded in a second region spaced from the first region, and the underside of the chuck table includes a third magnet embedded in a third region corresponding to the first region and attracted to the first magnet, and a fourth magnet embedded in a fourth region corresponding to the second region and attracted to the second magnet. and a fourth magnet which is attracted to the first magnet and the second magnet, and a compressed air supply means which supplies compressed air to the underside holding suction hole when the chuck table is attached to the support surface of the table base to form an air layer between the underside of the chuck table and the support surface of the table base , and the first region is an region in which the first magnet is embedded, which is formed in a ring shape surrounding the central suction hole, so that even if the chuck table is a relatively heavy object, the air layer formed between the underside of the chuck table and the support surface of the table base makes it easy to move the chuck table, and the magnets properly position the chuck table on the table base, eliminating the problem that it is difficult to attach the chuck table to the table base.

FIG. 2 is a perspective view of a cutting device equipped with a chuck table mechanism. 2 is an enlarged exploded perspective view of a portion of a chuck table mechanism attached to the cutting machine of FIG. 1 . FIG. 3A is a plan view of the table base shown in FIG. 2, and FIG. 3B is a cross-sectional view taken along the line AA in FIG. (a) Upper and lower oblique views, a B-B cross-sectional view, and a plan view of a 5-inch chuck table; (b) Upper and lower oblique views, a C-C cross-sectional view, and a plan view of a 6-inch chuck table. FIG. 13 is a perspective view showing an embodiment in which an operator attaches a chuck table to a table base. 6A to 6C are enlarged cross-sectional views of a portion of the chuck table and the table base, showing the embodiment shown in Figures 5 at different times. 6A and 6B are bottom perspective views showing another embodiment of the chuck table.

The following describes in detail an embodiment of a chuck table mechanism constructed according to the present invention, with reference to the attached drawings.

Figure 1 shows a cutting device 1 to which the chuck table mechanism 3 of this embodiment is applied. The cutting device 1 in the illustrated embodiment includes a roughly rectangular parallelepiped device housing 2, a chuck table mechanism 3 arranged as a holding means for holding a wafer 10, which is a workpiece, and a cutting means 4 equipped with a cutting blade 41 for cutting the wafer 10 held by the chuck table mechanism 3. As shown in the figure, the wafer 10 to be processed in this embodiment is, for example, a roughly disk-shaped semiconductor wafer with a diameter of 5 inches, with multiple devices formed on the surface partitioned by planned division lines, and is supported by an annular frame F via adhesive tape T.

The cutting device 1 further includes a cassette 5 (shown by a two-dot chain line) that accommodates a plurality of wafers 10, a temporary placement table 6 that transports and temporarily places the wafers 10 accommodated in the cassette 5, a carry-in/out means 7 that transports the wafers 10 to the temporary placement table 6, a transport means 8 that rotates and transports the wafers 10 transported to the temporary placement table 6 onto the chuck table mechanism 3, a cleaning means 9 (details omitted) that cleans the wafers 10 cut by the cutting means 4, a cleaning and transport means 11 that transports the cut wafers 10 from the chuck table mechanism 3 to the cleaning means 9, an imaging means 12 that images the wafers 10 on the chuck table mechanism 3, and a control means (not shown). The cassette 5 is placed on a cassette table 5a that is arranged so as to be movable up and down by a lifting means (not shown), and when the wafers 10 are transported from the cassette 5 by the carry-in/out means 7, the height of the cassette 5 is appropriately adjusted.

Inside the device housing 2, there is provided an X-axis feed means (not shown) which feeds the chuck table mechanism 3 and the cutting means 4 relative to one another for processing and moves the chuck table mechanism 3 in the X-axis direction indicated by the arrow X, which is the cutting feed direction.

2 shows a perspective view of the chuck table mechanism 3 mounted on the cutting device 1, in which the chuck table 20 for suction-holding the wafer 10 described above has been removed upward from the chuck table mechanism 3. As shown in the figure, the chuck table mechanism 3 includes a chuck table 20 having a holding surface 24a formed to a size for suction-holding, for example, a 5-inch diameter wafer 10 as shown in FIG. 1, a lower surface 20b opposite the holding surface 24a, and a table base 120 for detachably supporting the lower surface 20b of the chuck table 20. The chuck table 20 is configured to be rotatable together with the table base 120 by a rotation drive mechanism (not shown). As described later, the chuck table mechanism 3 is capable of replacing the chuck table according to the size of the wafer to be processed.

As shown in FIG. 2, the table base 120 has a support surface 122 that supports the lower surface 20b of the chuck table 20, a central suction hole 123 formed in the center of the support surface 122, and lower surface holding suction holes 127, 127 formed in the support surface 122 that suction-hold the lower surface 20b of the chuck table 20. In addition, the support surface 122 of the table base 120 has a first magnet 125 embedded in a first region C1 on the support surface 122, and a second magnet 126 embedded in a second region C2 spaced apart from the first region C1.

3(a) shows a plan view of the table base 120, and FIG. 3(b) shows a cross-sectional view taken along line A-A of FIG. 3(a). As can be seen from these figures, the first magnet 125 is formed in a ring shape and is embedded in the support surface 122 so as to surround the central suction hole 123 of the support surface 122. In this embodiment, the first magnet 125 is disposed so that the center of the first magnet 125 coincides with the center of the central suction hole 123. The first magnet 125 is disposed so that the upper surface 125a exposed to the support surface 122 is the N pole and the embedded lower surface 125b is the S pole, and the second magnet 126 is disposed so that the upper surface 126a exposed to the support surface 122 is the S pole and the embedded lower surface 126b is the N pole. As shown in FIG. 3(b), the distance between the center position of the first magnet 125 and the center position of the second magnet 126 is set to W0.

Returning to FIG. 2, the explanation is continued with respect to the underside holding suction holes 127, 127 of the table base 120 constituting the chuck table mechanism 3 of this embodiment, to which a compressed air supply means 140 and a suction means 150 are connected. The compressed air supply means 140 supplies compressed air H to the underside holding suction holes 127, 127 of the table base 120 via a compressed air supply path 142, an on-off valve 144 arranged on the compressed air supply path 142, and a communication path 146. The suction means 150 is connected to the communication path 146, which is also used for supplying compressed air H, via a suction path 152 and an on-off valve 154 arranged on the suction path 152, and operates the suction means 150 to generate a suction negative pressure V in the underside holding suction holes 127, 127 of the table base 120. In addition, a compressed air supply path and a suction path (not shown) are connected to the central suction hole 123 of the table base 120 via a communication passage 147, and it is configured so that compressed air H can be supplied or suction negative pressure V can be generated at any time, separately from the lower surface holding suction holes 127, 127.

The chuck table mechanism 3 of this embodiment is configured to be able to use multiple chuck tables with different outer diameters interchangeably, and can be equipped with not only the chuck table 20 for holding a 5-inch diameter wafer as shown in FIG. 2, but also the chuck table 30 for holding a 6-inch diameter wafer as shown in FIG. 4(b) and a chuck table for holding an 8-inch diameter wafer (not shown).

4(a) shows, from the upper part, an upper perspective view of the chuck table 20 seen from above, a B-B cross-sectional view of the chuck table 20, and a plan view of the chuck table 20, and on the right side of the upper perspective view of the chuck table 20 in the upper part, a lower perspective view of the chuck table 20 seen from below is shown. As can be seen from FIG. 4(a), the chuck table 20 is at least composed of a disk-shaped suction chuck 24 having a holding surface 24a for suction-holding a wafer with a diameter of 5 inches, and a frame 22 for surrounding the suction chuck 24 and supporting the outer periphery, and an internal space 221 is formed by the suction chuck 24 and the frame 22. A communication hole 222 is formed in the lower surface 20b of the chuck table 20, which is connected to the internal space 221 and is formed at a position corresponding to the central suction hole 123 formed in the table base 120 described above. The frame 22 is made of a metal such as SUS, and the suction chuck 24 is made of a porous ceramic such as alumina (Al ₂ O ₃ ).

4(a), on the lower surface 20b of the chuck table 20, when the chuck table 20 is positioned at a predetermined position on the table base 120, a third magnet 42 that attracts the first magnet 125 is disposed in a third region C3 corresponding to the first region C1, and a fourth magnet 44 that attracts the second magnet 126 is disposed in a fourth region C4 corresponding to the second region C2, and the upper surface 42a of the third magnet 42 is disposed as a north pole and the lower surface 42b is disposed as a south pole, and the upper surface 44a of the fourth magnet 44 is disposed as a south pole and the lower surface 44b is disposed as a north pole. The distance W1 between the center of the third magnet 42 and the center of the fourth magnet 44 of the chuck table 20 is the same as the distance W0 between the center position of the first magnet 125 and the center position of the second magnet 126 described above. As a result, when the chuck table 20 is positioned at a predefined position on the table base 120, the north pole of the upper surface 125a of the first magnet 125 and the south pole of the lower surface 42b of the third magnet 42 are attracted to each other, and the south pole of the upper surface 126a of the second magnet 126 and the north pole of the lower surface 44b of the fourth magnet 44 are attracted to each other.

4(b) shows, from the top, an upper perspective view of the chuck table 30 as seen from above, a CC cross-sectional view of the chuck table 30, and a plan view of the chuck table 30, and on the right side of the upper perspective view of the chuck table 30, a lower perspective view of the chuck table 30 as seen from below is shown. The chuck table 30 shown in FIG. 4(b) has a configuration substantially similar to that of the chuck table 20 described above, except that the diameter of the wafer it holds is 6 inches. That is, the chuck table 30 is at least composed of a disk-shaped suction chuck 34 having a holding surface 34a for suction-holding a wafer having a diameter of 6 inches, and a frame 32 for surrounding the suction chuck 34 to support the outer periphery, and an internal space 321 is formed by the suction chuck 34 and the frame 32. A communication hole 322 is formed in the lower surface 30b of the chuck table 30, which is connected to the internal space 321 and is located at a position corresponding to the central suction hole 123 formed in the table base 120. The frame 32 is made of a metal such as SUS, and the suction chuck 34 is made of a porous ceramic such as _alumina ( _Al2O3 ).

4B, on the lower surface 30b of the chuck table 30, when the chuck table 30 is positioned at a predetermined position on the table base 120, a third magnet 42 that attracts the first magnet 125 is disposed in a third region C3 corresponding to the first region C1, and a fourth magnet 44 that attracts the second magnet 126 is disposed in a fourth region C4 corresponding to the second region C2. More specifically, the upper surface 42a of the third magnet 42 is disposed to be the N pole and the lower surface 42b is disposed to be the S pole, and the upper surface 44a of the fourth magnet 44 is disposed to be the S pole and the lower surface 44b is disposed to be the N pole. The distance W2 between the center of the third magnet 42 and the center of the fourth magnet 44 of the chuck table 30 is the same as the distances W0 and W1 described above. As a result, when the chuck table 30 is positioned at a predetermined position on the table base 120, the north pole of the upper surface 125a of the first magnet 125 and the south pole of the lower surface 42b of the third magnet 42 are attracted to each other, and the south pole of the upper surface 126a of the second magnet 126 and the north pole of the lower surface 44b of the fourth magnet 44 are attracted to each other.

Returning to FIG. 2 to continue the explanation, the chuck table mechanism 3 of this embodiment includes a table base 110 on which the table base 120 is disposed, and four clamp mechanisms 130 disposed between the table base 110 and the table base 120. The table base 110 is formed in a cylindrical shape and configured to be rotatably driven to a desired angle by a servo motor (not shown).

The clamping mechanisms 130 are arranged between the table base 110 and the table base 120, with four of them being evenly spaced at 90° angles in the circumferential direction. Each clamping mechanism 130 is composed of a pair of guide rails 131 that protrude outward, a clamping portion 132 that is mounted so as to be movable radially along the guide rails 131, and a locking portion 133 for fixing the clamping portion 132 to the guide rails 131.

The clamp unit 132 has a clamp claw 134 that is rotated in the direction indicated by the arrow R1 by air supplied to the clamp unit 132, and the clamp claw 134 presses down on the frame F that holds the wafer 10 placed on the chuck table 20, fixing it to the clamp unit 132.

The guide rail 131 has a plurality of positioning grooves formed therein for fixing the clamp portion 132, which is moved in the direction indicated by the arrow R2 in accordance with the size of the annular frame that holds the wafer placed on the chuck table mechanism 3. The positioning groove 131a shown in the figure is for fixing the clamp portion 132 when holding a frame that holds an 8-inch wafer, and the positioning groove 131b is for fixing the clamp portion 132 when holding a frame that holds a 6-inch wafer. The clamp portion 132 shown in FIG. 2 is fixed by engaging the tip of the lock portion 133 (not shown) with the positioning groove for 5-inch wafers (not shown).

The cutting device 1 to which the chuck table mechanism 3 of this embodiment is attached has the configuration generally described above, and the functions and actions of the chuck table mechanism 3 of this embodiment will be described with reference to Figures 2, 5, and 6. Note that in the following embodiment, an embodiment in which the chuck table 20 that holds a 5-inch diameter wafer 10 is placed and attached to the table base 120 will be described.

2 is operated and the on-off valve 144 is opened, and compressed air H is ejected from the underside holding suction holes 127, 127 of the table base 120 via the compressed air supply path 142, the on-off valve 144, and the communication path 146. Next, as shown in FIG. 5, the operator holds the chuck table 20 with both hands and places it from above on the support surface 122 of the table base 120 of the chuck table mechanism 3 attached to the cutting device 1. 6A, when the operator places the chuck table 20 on the table base 120, in the initial state, the positions of the first magnet 125 embedded in the first region C1 of the support surface 122 of the table base 120, the third magnet 42 embedded in the third region C3 of the lower surface 20b of the chuck table 20, and the second magnet 126 embedded in the second region C2 of the support surface 122 and the fourth magnet 44 (shown by a broken line) embedded in the fourth region C4 of the lower surface 20b of the chuck table 20 do not match, so that the two are not in a specified positional relationship. At this time, compressed air H is supplied from the lower surface holding suction holes 127, 127 of the table base 120 described above between the lower surface 20b of the chuck table 20 and the support surface 122 of the table base 120 to form an air layer P, and the chuck table 20 floats above the table base 120. This allows the operator to easily move the chuck table 20, which is a heavy object, in the horizontal direction (the plane defined by the X and Y directions in FIG. 5), and as shown in FIG. 6(b), the third magnet 42 disposed in the third region C3 of the chuck table 20 can be easily positioned relative to the first magnet 125 embedded in the support surface 122 of the table base 120. When the third magnet 42 of the chuck table 20 is positioned relative to the first magnet 125 of the table base 120, the two magnets are attracted to each other by the action of the two magnets, and the center position of the table base 120 and the center position of the chuck table 20 are aligned, and the positions are fixed.

The first magnet 125 of the table base 120 and the third magnet 42 of the chuck table 20 are attracted to each other, so that the center positions of the table base 120 and the chuck table 20 are substantially fixed, and the chuck table 20 is movable in the rotation direction indicated by the arrow R3 in FIG. 5. Here, the operator rotates the chuck table 20 in the direction indicated by the arrow R3, as shown in FIG. 6(c), to position the fourth magnet 44 embedded in the fourth region C4 of the chuck table 20 relative to the second magnet 126 embedded in the second region C2 of the support surface 122 of the table base 120. As a result, the second magnet 126 of the table base 120 and the fourth magnet 44 of the chuck table 20 are attracted to each other, and the position of the chuck table 20 relative to the table base 120 is positioned at a specified position in a plan view.

As described above, once the chuck table 20 has been accurately positioned relative to the table base 120, the on-off valve 144 that supplies the compressed air H is closed, and the operation of the compressed air supply means 140 is stopped to stop the supply of compressed air H. This causes the chuck table 20 to descend, bringing the first magnet 125 and the third magnet 42 into close contact, and the second magnet 126 and the fourth magnet 44 into close contact, fixing the chuck table 20 in a specified positional relationship relative to the table base 120 and completing the installation.

Once the mounting of the chuck table 20 to the table base 120 is completed, the cutting machine 1 performs cutting processing on the wafer 10. When performing cutting processing, the suction means 150 described above is operated and the on-off valve 154 is opened to generate a suction negative pressure V in the lower surface holding suction holes 127, 127, and the chuck table 20 is sucked to the table base 120. Next, the wafer 10, which is the workpiece, is placed on the holding surface 24a of the chuck table 20, and the clamp mechanism 130 described above is operated to grip the frame F supporting the wafer 10, and a suction negative pressure V is generated in the central suction hole 123 via the communication passage 147 shown in FIG. 2 to hold the wafer 10 on the chuck table 20. Once the wafer 10 is held on the chuck table 20, the X-axis feed means (not shown) is operated to position the chuck table mechanism 3 directly below the imaging means 12 described above to take an image and perform the alignment process. Next, based on the position information of the processing position of the wafer 10 detected by the alignment process, the chuck table mechanism 3 is positioned directly under the cutting means 4, and the cutting blade 41 of the cutting means 4 cuts the planned division lines of the wafer 10, dividing the wafer 10 into individual device chips (details omitted).

As described above, once the wafer 10 has been divided into individual device chips, the clamp mechanism 130 releases the grip of the frame F, and compressed air H is supplied to the central suction hole 123 of the table base 120 described above to remove the wafer 10 from the chuck table 20. Note that in the above embodiment, an example has been shown in which the chuck table 20 holding a 5-inch diameter wafer 10 is attached to the table base 120 for the chuck table mechanism 3, but the chuck table 30 holding a 6-inch diameter wafer can also be attached in the same manner by the above procedure, and details thereof will be omitted.

According to the above-described embodiment, even if the chuck table 20 attached to the table base 120 is a relatively heavy weight, compressed air H is supplied between the lower surface 20b of the chuck table 20 and the support surface 122 of the table base 120 to form an air layer P, which facilitates horizontal movement of the chuck table 20 and allows the chuck table 20 to be moved horizontally on the table base 120 and positioned at an appropriate position, thereby eliminating the problem of difficulty in attaching the chuck table 20 to the table base 120.

Furthermore, in the above-described embodiment, the first magnet 125 and the second magnet 126 embedded in the support surface 122 of the table base 120 are set so that the magnetic poles exposed on the support surface 122 side are different, thereby preventing the fourth magnet 44 of the chuck table 20 from being mistakenly attracted to the first magnet 125 of the table base 120, or the third magnet 42 from being mistakenly attracted to the second magnet 126.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the fourth magnet 44 embedded in the fourth region C4 of the lower surface 20b of the chuck table 20 is shaped to have a circular cross section, but the chuck table 20A can be configured such that a magnet 46 having a rectangular cross section extending in the radial direction as shown in FIG. 7(a) is used as the fourth magnet, and the lower surface 46b of the magnet 46 has an N pole. If the fourth magnet is the above magnet 46, the second magnet 126 on the table base 120 side can also be a magnet having a rectangular cross section extending in the radial direction corresponding to the magnet 46, so that when the chuck table 20A is rotated in the direction indicated by the arrow R3 in FIG. 5, the position of the chuck table 20A relative to the table base 120 can be more accurately positioned at a specified position.

Furthermore, in the above embodiment, the third magnet 42 is arranged in the center of the lower surface 20b of the chuck table 20 in correspondence with the position of the ring-shaped first magnet 125 surrounding the central suction hole 123 arranged in the center of the support surface 122 of the table base 120, but the present invention is not limited to this, and for example, a configuration such as the chuck table 20B shown in Figure 7 (b) can be used. That is, in the chuck table 20B, a magnet 47 as a third magnet is arranged in a predetermined third region of the lower surface 20Bb, and a magnet 48 as a fourth magnet is arranged in a predetermined fourth region spaced from the magnet 47. In this embodiment, the bottom surface 47b of magnet 47 is set to the south pole, and the bottom surface 48b of magnet 48 is set to the north pole. Although not shown, a first magnet having a shape corresponding to magnet 47 is embedded in a first region of support surface 122 of table base 120 corresponding to magnet 47 described above, and a second magnet having a shape corresponding to magnet 48 is embedded in a second region spaced from the first region corresponding to magnet 48 described above.

Furthermore, in the above embodiment, the magnet embedded in the table base 120 is described as being a permanent magnet, but the present invention is not limited to this, and it is also possible for the magnet to be an electromagnet.

In the above embodiment, an example is shown in which the chuck table mechanism 3 of this embodiment is applied to a cutting device 1, but the present invention is not limited to this, and can also be applied to, for example, a laser processing device or a grinding device. Also, while the types of chuck tables supported by the table base 120 have been described as 5-inch, 6-inch, and 8-inch, other sizes may be supported, and the present invention is not limited to the above embodiment.

1: Cutting device 2: Device housing 3: Chuck table mechanism 20, 20A, 20B: Chuck table 30: Chuck table 20b, 30b: Lower surface 22, 32: Frame body 222, 322:
223, 323:
24, 34: suction chuck 24a, 34a: holding surface 4: cutting means 41: cutting blade 5: cassette 6: temporary placement table 7: loading/unloading means 8: transport means 9: cleaning means 11: cleaning transport means 12: imaging means 42: third magnet 42a: upper surface 42b: lower surface 44: fourth magnet 44a: upper surface 44b: lower surface 110: table base 120: table base 122: support surface 123: central suction hole 125: first magnet 125a: upper surface 125b: lower surface 126: third magnet No. 2 magnet 126a: upper surface 126b: lower surface 127: lower surface holding suction hole 130: clamp mechanism 131: guide rails 131a, 131b: positioning groove 132: clamp section 133: lock section 134: clamp claw 140: compressed air supply means 142: compressed air supply path 144: on-off valve 146: communication passage 147: communication passage 150: suction means 152: suction path 154: on-off valve C1: first region C2: second region C3: third region C4: fourth region

Claims (2)

The present invention includes a chuck table having a holding surface for holding a workpiece and a lower surface opposite to the holding surface, and a table base for detachably supporting the lower surface of the chuck table,
the table base includes a support surface that supports a lower surface of the chuck table, a central suction hole formed in a center portion of the support surface, and a lower surface holding suction hole formed in the support surface that holds the lower surface of the chuck table by suction,
the support surface of the table base includes a first magnet embedded in a first region and a second magnet embedded in a second region spaced from the first region;
the lower surface of the chuck table is provided with a third magnet embedded in a third region corresponding to the first region and attracting the first magnet, and a fourth magnet embedded in a fourth region corresponding to the second region and attracting the second magnet,
a compressed air supplying means for supplying compressed air to the lower surface holding suction hole when the chuck table is attached to the support surface of the table base, to form an air layer between the lower surface of the chuck table and the support surface of the table base ,
The first region is a chuck table mechanism in which the first magnet is embedded and is formed in a ring shape surrounding the central suction hole . 2. The chuck table mechanism according to claim 1 , wherein the first magnet embedded in the support surface of the table base has a magnetic pole exposed on the support surface, and the second magnet has a magnetic pole exposed on the support surface that is different from the magnetic pole exposed on the support surface .

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