JP6141153B2 - Foreign matter removal tool and foreign matter removal method - Google Patents

Description

  The present invention relates to a foreign matter removing tool and a foreign matter removing method for removing foreign matter from a holding table having a biconcave holding surface.

  When grinding debris such as fine silicon adheres firmly to the mounting surface of the suction chuck in a grinding apparatus or polishing apparatus, foreign matter such as grinding debris cannot be removed by a cleaning tool such as a brush. In the grinding device, the cleaning pad made of ceramics is brought into contact with the mounting surface of the suction chuck soiled by the grinding work, and the contact portion is slid relatively to adhere firmly to the mounting surface of the suction chuck. A chuck table cleaning device is provided that forcibly removes foreign matter such as cutting waste (Patent Document 1).

  On the other hand, TAIKO processing is known in a grinding apparatus (Patent Document 2). As the holding table of the grinding apparatus for TAIKO processing, a dedicated object (formed in a chuck table upper surface shape / biconcave shape suitable for TAIKO wafer grinding) is used (Patent Document 3).

JP 2001-326205 A JP 2007-019461 A JP 2008-060470 A

  The holding table for TAIKO grinding has a large double-concave shape as compared with a holding table for normal grinding (Patent Document 3). Therefore, if the normal cleaning method is performed with a cleaning pad for normal grinding (foreign material removal tool), the cleaning pad will be brought into contact with the center of the biconcave shape of the holding table and the apex of the outer periphery, and these apexes are missing. There is a problem that the life of the table is shortened due to excessive wear on the apex.

  The objective of this invention is providing the foreign material removal tool and foreign material removal method which can prolong the lifetime of a biconcave holding table conventionally.

  The foreign matter removing tool of the present invention has a holding surface made of a circular ceramic that holds a workpiece, the holding surface is concavely curved from the center toward the outer periphery, and the center of the holding surface is the axis of rotation. A foreign matter removing tool for removing foreign matter from the holding surface of the holding table that rotates as a circular grindstone portion made of a disc-shaped grindstone formed with an outer diameter equal to the radius of the holding surface of the holding table; A moving portion for positioning the circular grindstone portion in a radial region between the center of the holding surface and the outer peripheral edge of the holding table, and a circular grindstone portion that is rotatably connected to a lower end of the moving portion and holds the circular grindstone portion below. And the material of the surface of the circular grindstone that comes into contact with the holding surface of the holding table is made of a material having a bending strength smaller than the bending strength of the ceramic of the holding surface. It is characterized by being.

  In the foreign matter removing tool, it is preferable that a surface of the circular grindstone portion that comes into contact with the holding table is formed of ceramic or resin having a bending strength of JIS R1601 of 350 MPa or less.

  The foreign matter removing method of the present invention has a circular holding surface for holding a workpiece, the holding surface is concavely curved from the center toward the outer peripheral edge, and is driven to rotate about the center of the holding surface as a rotation axis. A foreign matter removing method for removing foreign matter from the holding surface of a holding table, the foreign matter removing tool positioning step for positioning the circular grindstone portion of the foreign matter removing tool in a radial region between the center and the outer peripheral edge of the holding surface. And a foreign matter removing step of removing foreign matter on the holding surface by rotating at least one of the holding table or the circular grindstone after performing the foreign matter removing tool positioning step. And

  The foreign matter removing tool according to the present invention includes a circular grindstone portion made of a disc-shaped grindstone formed with an outer diameter equivalent to the radius of the holding surface of the holding table, and the circular grindstone portion and the center and outer peripheral edge of the holding surface of the holding table. And a circular grindstone holding portion that is rotatably connected to the lower end of the moving portion and holds the circular grindstone portion below.

  The material of the surface that contacts the holding surface of the holding table of the circular grindstone is formed of a material having a bending strength smaller than the bending strength of the ceramic of the holding surface. According to the foreign matter removing tool according to the present invention, there is an effect that the life of the biconcave holding table can be extended compared to the conventional one.

FIG. 1 is a perspective view of a grinding apparatus according to an embodiment. FIG. 2 is a side view showing a main part of the foreign matter removing tool according to the embodiment. FIG. 3 is a perspective view showing a workpiece according to the embodiment. FIG. 4 is a perspective view showing a grinding process. FIG. 5 is a plan view for explaining the grinding process. FIG. 6 is a plan view showing the operation of the foreign matter removing tool of the embodiment. FIG. 7 is a side view showing the operation of the foreign matter removing tool of the embodiment. FIG. 8 is a diagram showing the influence on the wafer thickness when foreign matters are removed by the first comparative grindstone. FIG. 9 is a diagram showing the influence on the wafer thickness when foreign matters are removed by the second comparative grindstone. FIG. 10 is a diagram illustrating the influence on the wafer thickness when foreign matter is removed by the grindstone main body according to the embodiment. FIG. 11 is a view showing the holding surface after being cleaned by the first comparative grindstone. FIG. 12 is a view showing the holding surface after being cleaned by the second comparative grindstone. FIG. 13 is a view illustrating the holding surface after being cleaned by the grindstone main body according to the embodiment.

  Hereinafter, a foreign matter removing tool and a foreign matter removing method according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment]
The embodiment will be described with reference to FIGS. 1 to 13. The present embodiment relates to a foreign matter removing tool and a foreign matter removing method. FIG. 1 is a perspective view of a grinding apparatus according to an embodiment of the present invention, FIG. 2 is a side view showing a main part of a foreign matter removing tool according to the embodiment, and FIG. 3 is a perspective view showing a workpiece according to the embodiment. 4 is a perspective view illustrating grinding processing, FIG. 5 is a plan view illustrating grinding processing, FIG. 6 is a plan view illustrating the operation of the foreign matter removing tool of the embodiment, and FIG. 7 is foreign matter of the embodiment. It is a side view which shows operation | movement of a removal tool.

  FIG. 8 is a diagram showing the influence on the wafer thickness when foreign matters are removed by the first comparative grindstone, and FIG. 9 is the influence on the wafer thickness when foreign matters are removed by the second comparative grindstone. FIG. 10 is a diagram showing the influence on the wafer thickness when foreign matter is removed by the grindstone main body according to the embodiment, and FIG. 11 shows the holding surface after being cleaned by the first comparative grindstone. FIG. 12 is a view showing the holding surface after being cleaned by the second comparative grindstone, and FIG. 13 is a view showing the holding surface after being cleaned by the grindstone body according to the embodiment.

  The grinding apparatus 1 shown in FIG. 1 includes cassettes 23 and 24 for storing plate-like objects, carry-in / out means 7 for carrying out the plate-like objects from the cassette 23 or carrying the plate-like objects into the cassette 24, and a work piece. A center alignment table 8 for aligning the object W, a first conveying means 9 and a second conveying means 20 for conveying the plate-like object, a holding table 4 for sucking and holding the plate-like object on the upper part, and a holding table 4, a turntable 3 that can rotate while supporting 4, a grinding means 40 comprising a first grinding means 5 and a second grinding means 6 for grinding a plate-like object held on the holding table 4, and washing of the plate-like object And a cleaning means 21 to perform. Moreover, the foreign material removal tool 10 concerning this embodiment is comprised including the moving part 11 shown in FIG. 1, the circular grindstone part 12 shown in FIG. 2, and the circular grindstone part holding | maintenance part 13. As shown in FIG.

  Returning to FIG. 1, the main body 2 of the grinding apparatus 1 is a housing having a rectangular parallelepiped shape. The turntable 3 is disposed on the upper surface of the main body 2. The turntable 3 is rotatable about a vertical axis (Z axis). The turntable 3 is driven to rotate by a drive source such as a motor and rotates about the vertical axis. In the cassette 23, workpieces W before grinding (see FIG. 3), for example, semiconductor wafers, are stacked in a plurality of stages, and are picked up one by one by the loading / unloading means 7 and placed on the centering table 8. The Then, after the workpiece W is aligned here, the holding table 4 is attracted to the first conveying means 9 and the first conveying means 9 pivots as indicated by an arrow Y1. The workpiece W is placed on and held by suction.

  Next, the turntable 3 is rotated by a required angle, and the workpiece W is positioned immediately below the first grinding means 5. Then, the workpiece W positioned immediately below the first grinding means 5 is subjected to the action of the first grinding means 5 and the upper surface is ground.

  Here, in the first grinding means 5, a first grinding wheel 53 is fixed to a lower portion of a mounter 52 provided at the tip of a spindle 51 that is rotatably supported. As shown in FIG. A first grinding wheel 5a is annularly arranged below the wheel 53, and rough grinding is performed here. The first grinding wheel 5a is composed of a rough grinding wheel, for example, an abrasive grain having a grain size larger than that of grain size # 600.

  After the rough grinding is performed, the turntable 3 rotates by a required angle, the holding table 4 is positioned immediately below the second grinding means 6, and the work of the workpiece W is received by the action of the second grinding means 6. The top surface is ground.

  Here, in the second grinding means 6, a second grinding wheel 63 is fixed to the lower part of a mounter 62 provided at the tip of a spindle 61 rotatably supported. As shown in FIG. A second grinding wheel 6a is annularly arranged below the wheel 63, and finish grinding is performed here. The second grinding wheel 6a is composed of a grinding wheel for finish grinding, for example, an abrasive having a particle size smaller than the particle size of # 1000.

  In addition, the 1st grinding means 5 and the 2nd grinding means 6 which comprise the grinding means 40 can be moved up and down with respect to the wall body 27 provided upright, as shown in FIG. Here, since the 1st grinding means 5 and the 2nd grinding means 6 are comprised in substantially the same way, the same code | symbol is attached | subjected and demonstrated to a common site | part. A pair of rails 28 are provided in the vertical direction on the inner surface of the wall 27, and are slid by bolts 36 and 37 as the slide plate 35 moves up and down along the rails 28 when driven by the drive source 29. The first grinding means 5 and the second grinding means 6 fixed to the plate 35 move vertically. The grinding apparatus 1 can simultaneously perform grinding on one workpiece W by the first grinding means 5 and grinding on another workpiece W by the second grinding means 6.

  In the grinding apparatus 1 according to the present embodiment, four holding tables 4 are arranged on the turntable 3. The holding table 4 is arranged at a predetermined interval in the circumferential direction of the turntable 3, and is arranged at an equal interval, for example. The holding table 4 is a disk-shaped member having a circular shape in plan view.

  As described above, the holding table 4 holds the workpiece W. The holding table 4 has a circular holding surface 4a. The holding surface 4 a is disposed on the upper surface of the holding table 4. The holding surface 4a is a holding portion made of a porous member such as porous ceramic. The holding surface 4a of this embodiment is formed of a circular ceramic, for example, alumina ceramic. The holding surface 4a communicates with a suction source (not shown), and sucks and holds the workpiece W by a negative pressure supplied from the suction source.

  The holding table 4 is rotatable about a vertical axis (Z axis). The holding table 4 of the present embodiment is rotatable about the center of the holding surface 4a as the rotation axis Co (see FIG. 7). The holding table 4 is driven to rotate by the drive source 19 shown in FIG. 7 and rotates about the vertical axis. The drive source 19 is, for example, a motor.

  As will be described with reference to FIGS. 3 to 5, the grinding apparatus 1 of the present embodiment includes a device region W1 in which a plurality of devices D are formed and an outer peripheral surplus region W2 that surrounds the device region W1 as a surface Wa. The workpiece W provided for is processed. As shown in FIG. 3, the workpiece W has a disk shape and is a substrate made of a material such as silicon. A plurality of devices D such as semiconductor devices and optical devices are formed on the surface Wa of the workpiece W. The surface Wa includes a device region W1 where the device D is formed and an outer peripheral surplus region W2 surrounding the device region W1. In the present embodiment, the device region W1 has a circular shape, and the outer peripheral surplus region W2 has an annular shape.

  When grinding is performed, a protective member 25 such as a tape for protecting the device D is attached to the surface Wa of the workpiece W in advance. The workpiece W is placed on the holding table 4 with the protection member 25 and the holding surface 4a facing each other. That is, the holding surface 4 a sucks and holds the surface Wa of the workpiece W via the protective member 25.

  When processing the workpiece W, the first grinding means 5 and the second grinding means 6 form a recess W3 in a region corresponding to the device region W1 in the back surface Wb of the workpiece W as shown in FIG. Then, the ring-shaped reinforcing portion W4 is left on the outer peripheral side of the concave portion W3. The ring-shaped reinforcing portion W4 is a portion including the outer peripheral surplus region W2.

  FIG. 5 shows a workpiece W and first grinding means 5 (or second grinding means 6) during grinding. The diameters d1 of the outermost peripheries 5b and 6b of the grinding wheels 5a and 6a are larger than the radius R of the device region W1 and smaller than the diameter D of the device region W1. Further, the diameter d2 of the innermost circumferences 5c and 6c of the grinding wheels 5a and 6a is smaller than the radius R of the device region W1.

  While the workpiece W is rotated by the holding table 4, the grinding apparatus 1 contacts the rotating grinding wheels 5 a and 6 a with the back surface Wb of the workpiece W to grind the workpiece W. At this time, in the grinding apparatus 1, the grinding wheels 5a and 6a are in contact with the rotation center Wo of the workpiece W, and the grinding wheels 5a and 6a are positioned on the inner side (rotation center Wo side) from the outer peripheral surplus area W2. Next, the grinding wheels 5a and 6a are positioned.

  By such grinding (TAIKO), as shown in FIG. 4, a recess W3 is formed on the back surface Wb of the workpiece W, and a ring-shaped reinforcing portion W4 remains on the outer peripheral side of the recess W3. Since the outer peripheral side of the device region W1 is reinforced by the ring-shaped reinforcing portion W4, it is easy to handle the workpiece W after grinding.

  The holding table 4 included in the grinding apparatus 1 of the present embodiment has a shape that is advantageous for the above-described grinding, specifically, as shown in FIG. 7, the holding surface 4a has a biconcave shape. The holding surface 4a of the holding table 4 has a convex shape in which the shape of the central portion 4c near the rotation axis Co and the shape of the outer peripheral edge 4e are directed upward. The holding surface 4a has a concave shape in which the space between the central portion 4c and the outer peripheral edge 4e is curved downward. That is, the holding surface 4a is concavely curved from the rotation axis Co toward the outer periphery. In other words, the cross-sectional shape of the holding surface 4a in the cross section including the rotation axis Co is a biconcave shape having two concave portions 4b. The cross-sectional shape of the recess 4b is an arc shape in the present embodiment. The shape of the holding table 4 such as the depth of the recess 4b may be, for example, the shape disclosed in Patent Document 3.

  When the above-described grinding process (TAIKO process) is performed on the holding table 4 having the biconcave holding surface 4a, the in-plane thickness of the workpiece W can be made uniform while suppressing the occurrence of the iris-shaped streak. There is an effect.

  Here, in order to exhibit the effect of the biconcave shape, it is considered advantageous to increase the depth of the recess 4b to some extent. On the other hand, when the depth of the recess 4b is increased, there is a possibility of damaging the holding surface 4a when removing foreign matter from the holding table 4. For example, when cleaning is performed by pressing the holding pad 4a while rotating the cleaning pad for grinding as in the prior art, the cleaning pad is brought into contact with the central portion 4c and the outer peripheral edge 4e of the holding surface 4a. As a result, the vertex of the central portion 4c and the outer peripheral edge 4e may be lost during cleaning, or the vertex may be excessively worn and the life of the holding table 4 may be shortened.

  The foreign matter removing tool 10 of the present embodiment removes foreign matters from the holding surface 4a of the holding table 4, and includes the circular grindstone portion 12 shown in FIG. 2, the circular grindstone portion holding portion 13, and the movement shown in FIG. Part 11. As described with reference to FIGS. 6 and 7, the foreign matter removing tool 10 positions the circular grindstone portion 12 in a radial region 4 f between the rotation axis Co of the holding surface 4 a and the outer peripheral edge 4 e. The circular grindstone portion 12 positioned in the radius region 4 f rotates with the rotation of the holding table 4 to remove foreign matter on the upper surface of the holding table 4.

  The circular grindstone portion 12 of the foreign matter removing tool 10 is rotatably supported and rotates as the holding table 4 rotates. Thereby, the load with respect to the holding surface 4a by contacting with the circular grindstone part 12 is reduced, and wear and chipping of the center part 4c and the outer peripheral edge 4e are suppressed. Further, since the circular grindstone portion 12 is positioned in the radial region 4f, wear and chipping of the central portion 4c and the outer peripheral edge 4e are suppressed.

  The foreign material removal tool 10 will be described in detail with reference to FIGS. 1 and 2. As shown in FIG. 1, the moving part 11 of the foreign substance removing tool 10 includes a support part 11a, a guide rail 11b, an X-axis moving means 11c, a Z-axis moving means 11d, and a moving part main body 11e. Has been. The moving part main body 11e is a main body part that supports the circular grindstone holding part 13 and the circular grindstone part 12 shown in FIG. Returning to FIG. 1, the support portion 11 a is fixed to the main body 2 of the grinding device 1 and holds two guide rails 11 b. Each of the two guide rails 11b extends in the X-axis direction (the width direction of the grinding device 1). Further, the two guide rails 11b are arranged in parallel in the Z-axis direction with a predetermined interval, and are parallel to each other.

  The X-axis moving unit 11c moves the moving unit main body 11e relative to the main body 2 in the X-axis direction. The X-axis moving unit 11c is guided by the two guide rails 11b and moves in the X-axis direction. The drive source of the X-axis moving unit 11c can be, for example, a motor or compressed air.

  The Z-axis moving unit 11d moves the moving unit main body 11e relative to the main body 2 in the Z-axis direction. The Z-axis moving unit 11d is supported by the X-axis moving unit 11c. That is, the X-axis moving unit 11c supports the moving unit main body 11e via the Z-axis moving unit 11d. The drive source of the Z-axis moving unit 11d can be, for example, a motor or compressed air. The grinding apparatus 1 moves the moving unit main body 11e by the X-axis moving unit 11c and the Z-axis moving unit 11d.

  As shown in FIG. 2, a support shaft 14 is disposed below the moving unit main body 11e. The support shaft 14 protrudes downward from the lower surface of the moving part main body 11e. The circular grindstone holding portion 13 is an annular member having a through hole 13a in the center. The circular grindstone holding portion 13 is rotatably supported by a support shaft 14 and a support member 15. The support shaft 14 is inserted into the through hole 13 a of the circular grindstone holding portion 13 and protrudes below the circular grindstone holding portion 13. The support member 15 is fixed to the outer periphery of the lower end of the support shaft 14. The outer diameter of the support member 15 is larger than the outer diameter of the support shaft 14 and larger than the diameter of the through hole 13a (the inner diameter of the circular grindstone holding portion 13). Thereby, the circular grindstone holding portion 13 is supported from below by the support member 15.

  There is a slight gap between the inner peripheral surface surrounding the through hole 13 a of the circular grindstone holding portion 13 and the outer peripheral surface of the support shaft 14. It is desirable that the size of the gap allows the circular grindstone holding portion 13 to rotate relative to the support shaft 14 and can suppress the eccentricity of the circular grindstone holding portion 13 with respect to the support shaft 14. . Moreover, it is desirable that the size of the gap allows the circular grindstone portion holding portion 13 to move in the vertical direction. The circular grindstone holding portion 13 of the present embodiment is supported by the support member 15 and can freely rotate around the central axis of the support shaft 14 as a rotation center. That is, the circular grindstone holding part 13 is rotatably connected to the lower end of the moving part main body 11e of the moving part 11. Further, the circular grindstone holding portion 13 is movable relative to the support shaft 14 in the vertical direction.

  Further, the circular grindstone holding portion 13 holds the circular grindstone portion 12 below. The circular grindstone holding portion 13 of the present embodiment is connected to the circular grindstone 12 via an elastic member 16. The elastic member 16 of this embodiment is a coil spring. The circular grindstone portion 12 is disposed below the circular grindstone portion holding portion 13 and coaxially with the circular grindstone portion holding portion 13. Since the circular grindstone portion 12 is connected to the circular grindstone portion holding portion 13 via the elastic member 16, the circular grindstone portion 12 can move relative to the circular grindstone portion holding portion 13 in the vertical direction. Further, in the present embodiment, the circular grindstone holding unit 13 further supports the circular grindstone 12 via the grindstone support shaft 17.

  The grindstone support shaft 17 is fixed to the circular grindstone portion 12 and protrudes upward from the upper surface of the circular grindstone portion 12. The grindstone support shaft 17 is inserted into the elastic member 16 and is inserted into the through hole 13 b of the circular grindstone portion holding portion 13 so as to protrude upward from the circular grindstone portion holding portion 13. A support member 18 is fixed to the outer periphery of the upper end of the grindstone support shaft 17. The outer periphery of the support member 18 is larger than the outer diameter of the grindstone support shaft 17 and larger than the diameter of the through hole 13b. There is a slight gap between the inner peripheral surface surrounding the through hole 13 b of the circular grindstone holding portion 13 and the outer peripheral surface of the grindstone support shaft 17. The size of this gap allows the relative movement in the vertical direction of the grindstone support shaft 17 with respect to the circular grindstone portion holding portion 13. Moreover, it is preferable that the size of the gap is such that the circular grindstone holding portion 13 and the grindstone support shaft 17 can slide.

In the present embodiment, the circular grindstone holding portion 13 and the circular grindstone portion 12 are connected by the two elastic members 16, and the circular grindstone holding portion 13 and the circular grindstone portion 12 are connected by the two grindstone support shafts 17 and the support members 18. And are connected. The two elastic members 16 are preferably disposed at symmetrical positions with the rotation axis of the circular grindstone 12 interposed therebetween. Moreover, it is preferable that the two grindstone support shafts 17 are disposed at symmetrical positions with the rotation axis of the circular grindstone portion 12 in between.
The elastic member 16 is disposed between the circular grindstone portion holding portion 13 and the circular grindstone portion 12 in a compressed state. Accordingly, the elastic member 16 applies a downward biasing force to the circular grindstone portion 12.

  The circular grindstone 12 contacts the radius region 4f of the holding surface 4a. The circular grindstone portion 12 is made of a disc (disc) shaped ceramic grindstone. The circular grindstone portion 12 of the present embodiment includes a grindstone main body 12a and a grindstone holding portion 12b. The grindstone main body 12a is a disc-shaped ceramic grindstone. The grindstone holding portion 12b is a disk-shaped member that holds the grindstone main body 12a. The grindstone holding part 12b is attached to the upper surface of the grindstone main body 12a. Therefore, in this embodiment, the elastic member 16 and the grindstone support shaft 17 are connected to the grindstone holding portion 12b. The outer diameter of the grindstone holding part 12b is the same as the outer diameter of the grindstone main body 12a or slightly larger than the outer diameter of the grindstone main body 12a.

  Next, the foreign substance removal of the holding table 4 by the foreign substance removal tool 10 will be described. When removing foreign matter from the holding table 4, the foreign matter removing tool 10 positions the circular grindstone 12 in the radial region 4 f of the holding table 4 on which the workpiece W is not placed. More specifically, the moving unit 11 first moves the circular grindstone unit 12 above the target holding table 4 (hereinafter simply referred to as “target holding table 4”) from which foreign matter is to be removed. The moving unit 11 moves the circular grindstone unit 12 above the target holding table 4 by the X-axis moving unit 11c. The target position of the circular grindstone 12 in the X-axis direction at this time is determined in advance, for example.

  The stop position of the turntable 3, that is, the stop position of the holding table 4 is determined in advance. Therefore, the stop position of the circular grindstone portion 12 corresponding to the radius region 4f of the target holding table 4 can be determined in advance. The moving unit 11 moves the circular grindstone unit 12 to a predetermined target position by the X-axis moving unit 11c, thereby positioning the circular grindstone unit 12 directly above the radial region 4f of the target holding table 4.

  Next, the moving part 11 lowers the circular grindstone part 12 by the Z-axis moving means 11d and brings the grindstone main body 12a into contact with the holding surface 4a. The target position in the Z-axis direction of the circular grindstone 12 at this time is determined in advance, for example. In the present embodiment, as shown in FIG. 6, a part of the outer periphery 12 c of the grindstone main body 12 a comes into contact with and comes into contact with the holding surface 4 a. As a configuration in which a part of the outer periphery 12c is brought into contact with the holding surface 4a in this way, in this embodiment, the rotation axis of the holding table 4 is inclined with respect to the vertical axis. More specifically, the rotating shaft of the holding table 4 is inclined so that a portion 12d (hereinafter referred to as “contact portion 12d”) corresponding to about a half circumference of the outer periphery 12c contacts the holding surface 4a. The direction of the inclination of the rotation axis of the holding table 4 is a direction in which a portion of the grindstone main body 12a located on the front side in the rotation direction of the holding table 4 contacts the holding surface 4a.

  The rotation direction of the holding table 4 is a counterclockwise direction in FIG. In the holding table 4 that rotates in this rotational direction, the rotation axis of the holding table 4 is tilted so that the left half of the outer periphery 12c of the grindstone body 12a is in contact with the holding surface 4a as a contact portion 12d. .

  The moving part 11 positions the circular grindstone part 12 in the radial area 4f by bringing the contact portion 12d into contact with the radial area 4f of the holding surface 4a. FIG. 7 shows a view A in FIG. As shown in FIG. 7, the radius region 4f is a region from the rotation axis Co of the holding table 4 to the outer peripheral edge 4e in the radial direction. The moving portion 11 positions the circular grindstone portion 12 in the radial region 4f on one side with respect to the rotation axis Co, that is, in one concave portion 4b having a biconcave shape.

  The contact portion 12d of the circular grindstone portion 12 positioned in the radius region 4f is in contact with the radius region 4f of the holding surface 4a so that the foreign matter on the holding surface 4a can be removed. As shown in FIG. 7, the outer diameter Dw of the grindstone body 12 a of the present embodiment is the same as or slightly larger than the radius Rt of the holding table 4. In the present embodiment, the grindstone main body 12a abuts from one end to the other end of the radius region 4f. In other words, the grindstone main body 12a is in contact from one end to the other end of the arc of the recess 4b. Therefore, the grindstone main body 12a can remove foreign substances from the entire holding surface 4a.

  The circular grindstone portion 12 positioned in the radius region 4 f rotates with the rotation of the holding table 4 to remove foreign matters on the upper surface of the holding table 4. When the holding table 4 rotates counterclockwise, the circular grindstone portion 12 rotates in the same direction as the rotation direction of the holding table 4, that is, counterclockwise. Thereby, the grindstone main body 12a contacts the holding surface 4a, rotates while sliding with the holding surface 4a, and removes the foreign matter on the upper surface of the holding table 4. The number of rotations of the holding table 4 is preferably about 60 rpm, for example, but is not limited thereto.

  In the foreign matter removing tool 10 of the present embodiment, the circular grindstone portion 12 rotates as the holding table 4 rotates. The circular grindstone portion 12 is rotatably supported and rotates with the rotation of the holding table 4, so that the relative rotation speed and the relative movement speed with respect to the holding surface 4a are suppressed from becoming excessively high. Therefore, damage to the holding surface 4a is suppressed as compared with the case where the circular grindstone portion 12 is forcibly rotated by a motor or the like.

  Moreover, in the foreign material removal tool 10 of this embodiment, the circular grindstone part 12 is connected with the circular grindstone part holding part 13 via the elastic member 16. The circular grindstone portion 12 can move in the vertical direction by expanding and contracting the elastic member 16. Thereby, compared with the case where the circular grindstone part 12 cannot move to an up-down direction, it is suppressed that the circular grindstone part 12 is pressed toward the holding surface 4a with big force. In the present embodiment, the grindstone main body 12 a is pressed toward the holding surface 4 a by a force obtained by combining the pressing force due to the weight of the circular grindstone portion 12 and the pressing force due to the urging force of the elastic member 16.

  The pressing force by the urging force of the elastic member 16 is appropriately determined. The urging force of the elastic member 16 may be, for example, a force that can prevent the grindstone body 12a from being lifted from the holding surface 4a when removing the foreign matter. The urging force of the elastic member 16 is preferably determined based on a fitting experiment or the like so that both the effect of removing foreign matter and the suppression of damage to the holding surface 4a can be achieved. The urging force of the elastic member 16 may be set, for example, such that the pressing force due to the urging force is smaller than the pressing force due to its own weight.

  Here, it is desired that the cleaning effect at the time of removing the foreign matter on the holding surface 4a of the holding table 4 can be improved and that the wear of the central portion 4c and the outer peripheral edge 4e can be suppressed. For example, when removing foreign matter from the holding table 4, there is a possibility that the central portion 4 c and the outer peripheral edge 4 e of the holding surface 4 a are worn due to contact with the circular grindstone portion 12. If the shape of the holding surface 4a changes due to wear, the finished thickness of the ground workpiece W may vary, which is not preferable. Moreover, if the cleaning effect by the foreign material removal tool 10 can be improved, it is possible to shorten the cleaning time for one time.

  It is considered that the outer diameter and material of the grindstone main body 12a of the circular grindstone portion 12 are related to the cleaning effect and the wear of the holding surface 4a. For example, if the outer diameter Dw of the grindstone main body 12a is too large with respect to the radius Rt of the holding surface 4a of the holding table 4, the grindstone main body 12a may not be evenly contacted with the radius region 4f. In addition, if the outer diameter of the grindstone main body 12a is large, the grindstone main body 12a may come into contact with the central portion 4c and the outer peripheral edge 4e to wear them when removing foreign matter.

  In the foreign matter removing tool 10 of the present embodiment, the circular grindstone portion 12 is composed of a disc-shaped grindstone main body 12 a formed with an outer diameter Dw equivalent to the radius Rt of the holding surface 4 a of the holding table 4. The outer diameter Dw of the grindstone body 12a is equal to the radius Rt of the holding surface 4a. In the present embodiment, the radius Rt of the holding surface 4a is 150 [mm]. On the other hand, the outer diameter Dw of the grindstone main body 12a is 152.5 [mm]. That is, the outer diameter Dw of the grindstone main body 12a is slightly larger than the radius Rt of the holding surface 4a. This is due to the following reason.

(1) To reduce the difference between the outer diameter Dw of the grindstone body 12a and the outer diameter of the grinding wheels 5a and 6a for grinding.
The diameters d1 (see FIG. 5) of the outermost peripheries 5b and 6b of the grinding wheels 5a and 6a are smaller than the radius Rt (see FIG. 7) of the holding surface 4a. If the difference between the diameter d1 of the grinding wheels 5a, 6a and the outer diameter Dw of the grinding wheel main body 12a is too large, it may affect the grinding of the workpiece W, so that the difference between the two is preferably small.

(2) The same diameter as the outer diameter of the self-grinding wheel.
In the grinding device 1, the concave portion 4 b of the holding surface 4 a is re-formed (shape correction) by the self-grinding stone every certain period (constant operation time). The self grindstone is a grindstone different from the grinding grindstones 5a and 6a, and is used when forming or re-forming the recess 4b. The formation and re-formation of the recess 4b is performed in the same manner as the holding surface grinding process of Patent Document 3, for example. The self-grinding wheel grinds the holding surface 4a and a stainless steel frame portion surrounding the holding surface 4a to form a recess 4b in the holding surface 4a. The outer diameter of the self-grinding wheel is set to a diameter slightly larger than the radius Rt of the holding surface 4a, for example, 152.5 [mm] so that a portion of a width of several mm adjacent to the holding surface 4a in the frame portion can be ground. Yes. The outer diameter Dw of the grindstone main body 12a of this embodiment is the same as the outer diameter of the self-grinding stone.

  Since the outer diameter Dw of the grindstone main body 12a is equal to the radius Rt of the holding surface 4a, as shown in FIG. 7, the grindstone main body 12a abuts the recess 4b of the holding surface 4a entirely, for example, uniformly. Therefore, the grindstone main body 12a can remove foreign substances from the entire recess 4b. Moreover, since the outer diameter Dw of the grindstone main body 12a is equal to the radius Rt of the holding surface 4a, the grindstone main body 12a is prevented from damaging the central portion 4c and the outer peripheral edge 4e of the holding surface 4a.

  From the viewpoint of suppressing the wear of the holding surface 4a, it is desirable to use an appropriate material for the surface of the circular grindstone portion 12 that contacts the holding surface 4a. For example, if a material having a bending strength that is too high is used as the material of the grindstone main body 12a, the center portion 4c and the outer peripheral edge 4e may be worn.

  In the foreign matter removing tool 10 according to the present embodiment, the material of the grindstone body 12a of the circular grindstone portion 12 is formed of a material having a bending strength smaller than the bending strength of the ceramic of the holding surface 4a. The bending strength of the ceramic of the holding surface 4a, for example, alumina ceramic, is 350 MPa to 450 MPa. In addition, the bending strength in this specification shall show JISR1601 bending strength. The lower surface of the grindstone main body 12a, that is, the surface that contacts the holding table 4 of the circular grindstone 12 is preferably formed of ceramic or resin having a bending strength of JIS R1601 of 350 MPa or less. According to such a combination of the grindstone main body 12a and the holding surface 4a, the holding surface 4a formed of alumina ceramic can be cleaned by the grindstone main body 12a made of a material having a bending strength smaller than that of alumina ceramic. Made. Therefore, the wear of the holding surface 4a is suppressed.

  The material of the grindstone main body 12a of this embodiment is polyphenylene sulfide resin (hereinafter referred to as “PPS resin”). The bending strength of the PPS resin is, for example, about 100 MPa. By using the grindstone main body 12a having a bending strength smaller than the bending strength of the ceramic of the holding surface 4a, wear of the central portion 4c and the outer peripheral edge 4e when removing foreign matters is suppressed.

  Below, with reference to FIG. 8 thru | or FIG. 13, the advantage of the foreign material removal tool 10 which concerns on this embodiment is demonstrated. 8 to 10 are diagrams showing experimental results related to wear of the holding surface 4a during cleaning. 8 to 10 show the thickness distribution of the workpiece W after being held on the holding surface 4a and ground. In each figure, the horizontal axis indicates the radial position of the workpiece W, that is, the distance from the center of the workpiece W. The vertical axis indicates the thickness of the workpiece W.

  FIGS. 8 to 10 show the influence on the thickness distribution of the workpiece W when the holding surface 4a is cleaned with the grindstone body 12a of a different outer diameter or a different material. The inventor of the present application performs a cleaning test on the holding surface 4a with each of the grindstones using two comparative grindstones as a comparison object in addition to the grindstone main body 12a according to the present embodiment, and wear by the grindstone main body 12a of the present embodiment. The inhibitory effect and cleaning performance were confirmed.

The experimental result shown in FIG. 10 has shown the experimental result at the time of wash | cleaning using the grindstone main body 12a which concerns on this embodiment. In this specification, the comparative grindstone body 12a used in the experiment of FIG. 8 is referred to as “first comparative grindstone”, and the comparative grindstone body 12a used in the experiment of FIG. This is referred to as a “whetstone”. The material and outer diameter of each grindstone are as follows.
First comparative grinding wheel (Fig. 8) Material: Alumina ceramic Outer diameter: 180.0mm
Second comparative grinding wheel (Fig. 9) Material: Alumina ceramic Outer diameter: 152.5mm
Grinding wheel main body 12a of embodiment Material: PPS resin Outer diameter: 152.5 mm

  That is, the first comparative grindstone is different from the grindstone main body 12a of the present embodiment in both material and outer diameter. The second comparative grindstone has the same outer diameter as that of the grindstone main body 12a of the present embodiment, but the material is different from that of the grindstone main body 12a. FIGS. 8 to 10 show the influence on the thickness distribution of the workpiece W after grinding when the holding surface 4a is continuously cleaned for a predetermined time by each grindstone.

  In FIG. 8, the thickness distribution A <b> 1 indicates the thickness distribution of the workpiece W that is held and ground by the holding surface 4 a before cleaning by the foreign matter removing tool 10. In other words, the thickness distribution A1 indicates the thickness distribution of the workpiece W that is held and ground by the holding surface 4a immediately after the recess 4b is formed by the self-grinding stone. On the other hand, the thickness distribution B1 is obtained when the holding surface 4a is continuously cleaned by the foreign matter removing tool 10 equipped with the first comparative grindstone, and the workpiece W held on the holding surface 4a after cleaning is ground. The thickness distribution of the workpiece W is shown.

  Here, the shape of the holding surface 4a after being continuously cleaned is an experiment on the shape of the holding surface 4a after the grinding apparatus 1 grinds a predetermined number of workpieces W during mass production (actual operation). It can be said that it has been reproduced. At the time of mass production by the grinding apparatus 1, each time one workpiece W is ground, the holding surface 4 a is cleaned for a short time by the foreign matter removing tool 10 after grinding. For example, every time one workpiece W is ground, the foreign object removal tool 10 performs 2 [sec] cleaning. Let Tt be the cumulative cleaning time during a predetermined number of grinding operations. In the verification experiment, the shape of the holding surface 4a after a predetermined number of grinding operations can be reproduced in actual operation by cleaning the holding surface 4a continuously for the accumulated time Tt with the foreign matter removing tool 10.

  The thickness distribution B1 shows the thickness distribution of the workpiece W that has been held and ground by the holding surface 4a experimentally reproduced in this way. In the experiment of FIG. 8, the holding surface 4 a was continuously cleaned for 16 hours by the foreign matter removing tool 10. This cleaning time is comparable to the total cleaning time Tt that is performed after the recess 4b is formed on the holding surface 4a and until the next recess 4b is re-formed. For example, assuming that the interval from the formation of one recess 4b to the re-formation of the recess 4b is 6 months, the cumulative time Tt for continuous cleaning in the experiment is determined from the number of workpieces W to be ground during this period. It was.

  As shown in FIG. 8, in the thickness distribution A1 before cleaning and the thickness distribution B1 after cleaning, the thickness of the central portion of the workpiece W changes by about 0.8 [μm]. When the workpiece W is held and ground by the holding surface 4a after cleaning, the thickness of the central portion of the workpiece W is larger than that when the workpiece W is held by the holding surface 4a before cleaning. It has increased by about 0.8 [μm]. This shows the result of the central portion 4c of the holding surface 4a being worn by the cleaning with the foreign matter removing tool 10. When the central portion 4c is worn, the thickness removed by grinding at the central portion of the workpiece W decreases. As a result, the thickness distribution B1 is such that the central portion of the workpiece W after grinding protrudes from the periphery.

  The first comparative grindstone according to the experiment of FIG. 8 uses the grindstone main body 12a formed of a material having the same bending strength as the material of the holding surface 4a, and the outer diameter Dw (= 180 mm) of the grindstone main body 12a. However, it is considered that the central portion 4c has been worn because it is too large with respect to the radius Rt (= 150 mm) of the holding surface 4a.

  In FIG. 9, the thickness distribution C <b> 1 indicates the thickness distribution of the workpiece W that has been held and ground by the holding surface 4 a before being cleaned by the foreign matter removing tool 10. The thickness distribution D1 is determined when the holding surface 4a is continuously cleaned by the foreign matter removing tool 10 on which the second comparative grindstone is mounted, and the workpiece W held on the holding surface 4a after cleaning is ground. The thickness distribution of the workpiece W is shown. In the experiment shown in FIG. 9, the cumulative cleaning time Tt is 4 hours. This time is shorter than the cumulative cleaning time for 6 months. In the thickness distribution C1 before cleaning and the thickness distribution D1 after cleaning, the thickness of the central portion of the workpiece W changes by about 0.7 [μm]. When the workpiece W is held and ground by the holding surface 4a after cleaning, the thickness of the central portion of the workpiece W is larger than that when the workpiece W is held by the holding surface 4a before cleaning. It has increased by 0.7 [μm].

  This shows the result of the central portion 4c of the holding surface 4a being worn by the cleaning with the foreign matter removing tool 10. The second comparative grindstone according to the experiment of FIG. 9 has the outer diameter Dw (= 152.5 mm) of the grindstone main body 12a equivalent to the radius Rt (= 150 mm) of the retaining surface 4a, but the bending strength of the retaining surface 4a. It is considered that the central portion 4c is worn by being made of the same bending strength material.

  In FIG. 10, the thickness distribution E <b> 1 indicates the thickness distribution of the workpiece W that is held and ground by the holding surface 4 a before cleaning by the foreign matter removing tool 10. The thickness distribution F <b> 1 indicates the thickness distribution of the workpiece W that is held and ground by the holding surface 4 a after being cleaned by the foreign matter removing tool 10. In the experiment shown in FIG. 10, the cumulative cleaning time Tt is 17 hours. The change in the thickness of the central portion of the workpiece W is as small as about 0.4 [μm] between the thickness distribution E1 before cleaning and the thickness distribution F1 after cleaning. Further, the thickness distribution F1 after cleaning does not increase in thickness at the center of the workpiece W with respect to the thickness distribution E1 before cleaning. This is considered to indicate that no wear has occurred in the central portion 4c of the holding surface 4a due to the cleaning by the foreign matter removing tool 10.

  Further, as shown in FIG. 10, no increase in thickness occurs after cleaning even at the outer peripheral edge of the workpiece W. Therefore, it can be seen that the outer peripheral edge 4e of the holding surface 4a is not worn by the cleaning with the foreign matter removing tool 10.

  As described above, the foreign matter removing tool 10 of the present embodiment is such that the material of the grindstone main body 12a is formed of a material having a bending strength smaller than the bending strength of the ceramic of the holding surface 4a. The holding surface 4a can be cleaned without wearing the portion 4c and the outer peripheral edge 4e.

  As shown in FIGS. 11 to 13, the foreign matter removing tool 10 of the present embodiment has a high ability to remove foreign matter from the holding surface 4a. FIG. 11 to FIG. 13 are views showing the state of adhesion of the grinding waste Cn on the holding surface 4a after being cleaned by the foreign matter removing tool 10. FIG. FIG. 11 shows the holding surface 4a after being cleaned by the first comparative grindstone, and FIG. 12 shows the holding surface 4a after being cleaned by the second comparative grindstone. FIG. 13 shows the holding surface 4a after being cleaned by the grindstone body 12a according to the present embodiment. The cleaning time of the cleaning according to FIGS. 11 to 13 is the same.

  The holding surface 4a shown in FIG. 12 has less adhesion of the grinding dust Cn to the holding surface 4a shown in FIG. Therefore, in the case of the grindstone main body 12a made of the same material, it can be seen that the cleaning performance is enhanced when the outer diameter Dw is equal to the radius Rt of the holding surface 4a. In addition, with the holding surface 4a shown in FIG. 13, the adhesion of the grinding waste Cn is less than the holding surface 4a shown in FIG. That is, the grindstone main body 12a of PPS resin can remove the grinding dust Cn from the holding surface 4a more effectively than the second comparative grindstone made of alumina ceramic.

  As described above, the foreign matter removing tool 10 according to the present embodiment is formed so that the material of the grindstone main body 12a is formed of a material having a bending strength smaller than the bending strength of the ceramic of the holding surface 4a. The lifetime of the shape holding table 4 can be extended compared to the conventional one. Further, the foreign matter removing tool 10 has a circular grindstone portion 12 comprising a disc-shaped grindstone main body 12a formed with an outer diameter Dw equivalent to the radius Rt of the holding surface 4a, thereby extending the life of the holding table 4. It is possible to exhibit a high cleaning ability for the holding surface 4a. Note that the lower surface of the grindstone main body 12a, that is, the surface in contact with the holding table 4 of the circular grindstone portion 12 is preferably formed of ceramic or resin having a JIS R1601 bending strength of 350 MPa or less, for example, JIS R1601 bending strength. And may be formed of ceramic or resin of 100 MPa or less.

  The grinding apparatus 1 of the present embodiment can execute the foreign matter removing method shown below. The foreign matter removing method has a circular holding surface 4a for holding the workpiece W, the holding surface 4a is concavely curved from the center toward the outer peripheral edge 4e, and is driven to rotate about the center of the holding surface 4a as the rotation axis. This is a foreign matter removing method for removing foreign matter from the holding surface 4 a of the holding table 4. The foreign matter removing method includes a foreign matter removing tool positioning step and a foreign matter removing step.

(Foreign substance removal tool positioning process)
The foreign matter removing tool positioning step is a step of positioning the circular grindstone portion 12 of the foreign matter removing tool 10 in the radial region 4f between the center of the holding surface 4a and the outer peripheral edge 4e. In the foreign matter removing step, the moving unit 11 positions the circular grindstone unit 12 in the radius region 4f as shown in FIG. In the circular grindstone portion 12 positioned in the radius region 4f, the contact portion 12d is in contact with the holding surface 4a.

(Foreign substance removal process)
The foreign matter removing step is executed after the foreign matter removing tool positioning step. In the foreign matter removing step, the grinding device 1 rotates the holding table 4. As shown in FIG. 7, when the holding table 4 rotates, the circular grindstone 12 rotates along with the concave shape of the holding surface 4 a of the holding table 4 to remove foreign matters on the holding surface 4 a. The grinding apparatus 1 may start the rotation of the holding table 4 after the foreign matter removing tool positioning step is completed, or may start the rotation of the holding table 4 before or during the foreign matter removing tool positioning step. Good.

  In the foreign matter removing tool of the present embodiment, the circular grindstone holding portion 13 may not be movable relative to the support shaft 14 in the vertical direction. That is, the circular grindstone holding portion 13 may be relatively rotatable with respect to the support shaft 14 and may not be relatively movable in the vertical direction. In this case, for example, the circular grindstone holding part 13 is connected to the support shaft 14 via a bearing. Even if the circular grindstone holding portion 13 cannot move in the vertical direction, the circular grindstone portion 12 can move in the vertical direction. Therefore, it is suppressed that the pressing force of the circular grindstone portion 12 against the holding surface 4a becomes too large. Further, since the circular grindstone portion 12 is rotatably supported together with the circular grindstone portion holding portion 13, the circular grindstone portion 12 can rotate as the holding table 4 rotates.

  The elastic member 16 that connects the circular grindstone portion 12 and the circular grindstone portion holding portion 13 is not limited to a coil spring, and may be a leaf spring, for example. For example, it is possible to employ a leaf spring in which both end portions in the width direction are fixed to the upper surface of the circular grindstone portion 12 and the central portion protrudes toward the circular grindstone portion holding portion 13. In this case, by connecting the central portion of the leaf spring to the circular grindstone portion holding portion 13, the circular grindstone portion 12 can be moved relative to the circular grindstone portion holding portion 13 in the vertical direction by deformation of the leaf spring.

[First Modification of the Embodiment]
In the above embodiment, the target position in the X-axis direction of the circular grindstone portion 12 when the circular grindstone portion 12 is positioned in the radius region 4f has been determined in advance, but instead of this, for example, detection of the position of the holding table 4 The target position may be determined based on the result.

  In the above embodiment, the target position in the Z-axis direction of the circular grindstone portion 12 when the circular grindstone portion 12 is positioned in the radius region 4f is determined in advance, but instead, for example, the grindstone main body 12a is actually held. You may make it detect having contacted the surface 4a. For example, when the circular grindstone portion 12 is lowered while the holding table 4 is rotated, when the grindstone main body 12 a comes into contact with the holding table 4, the circular grindstone portion 12 starts to rotate. Therefore, for example, when the rotation of the circular grindstone portion 12 is detected, it may be determined that the grindstone main body 12a is in contact with the holding surface 4a and the circular grindstone portion 12 is positioned in the radius region 4f.

  In the above embodiment, the foreign matter removing tool 10 is provided in the grinding device 1, but instead, the foreign matter removing tool 10 may be provided in another processing device, for example, a polishing device.

  In the above-described embodiment, the elastic member 16 is disposed between the circular grindstone portion 12 and the circular grindstone portion holding portion 13 in a state in which the elastic member 16 is compressed, but instead, the elastic member 16 is extended. It may be arranged in a state.

[Second Modification of the Embodiment]
A second modification of the above embodiment will be described. The material of the grindstone main body 12a is not limited to PPS resin. Examples of the resin that can be used as the material of the grindstone main body 12a include polyether ether ketone (PEEK) resin, polyarylate (PAR) resin, polyamideimide (PAI) resin, polyvinylidene fluoride (PVDF) resin, and polyacetal (POM). ) Resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and the like.

Moreover, as a ceramic which can be used as the material of the grindstone main body 12a, cordierite (cordierite: 2MgO · 2Al ₂ O ₃ · 5SiO ₂ ), sialon (Si ₃ N ₄ · Al ₂ O ₃ ), mullite (3Al ₂ O ₃ · 2SiO ₂ ).

[Third Modification of the Embodiment]
A third modification of the above embodiment will be described. In the foreign matter removal method executed by the foreign matter removal tool 10 of the above embodiment, the circular grindstone portion 12 may be rotated in the foreign matter removal step. When the circular grindstone portion 12 is rotationally driven, the circular grindstone portion holding portion 13 is desirably connected to the support shaft 14 so as not to rotate relative to the support shaft 14. The moving unit 11 preferably has a driving source such as a motor that rotationally drives the circular grindstone holding unit 13.

  The foreign matter removing tool 10 shown in FIG. 2 will be described as an example. When the circular grindstone portion 12 is rotationally driven, for example, the support shaft 14 and the circular grindstone portion holding portion 13 cannot be rotated relative to each other, for example, by spline fitting. Connected. Further, it is desirable that the moving unit main body 11e has a drive source such as a motor for rotating the support shaft 14 therein. That is, the support shaft 14 is rotatably supported by the moving unit main body 11e, and is rotated by a motor to rotate relative to the moving unit main body 11e. Thereby, the support shaft 14, the circular grindstone part holding | maintenance part 13, and the circular grindstone part 12 rotate integrally by the rotational force which a motor generate | occur | produces.

  In the foreign matter removing step, the foreign matter on the holding surface 4a may be removed by rotating at least one of the holding table 4 or the circular grindstone 12. That is, the holding table 4 may be rotationally driven while the circular grindstone portion 12 may be rotated around the holding surface 4a in a rotatable state. Moreover, both the holding table 4 and the circular grindstone 12 may be driven to rotate. Further, while the circular grindstone 12 is driven to rotate, the holding table 4 may be rotatable. When the circular grindstone 12 is rotated in the foreign matter removing process, it can be expected that the effect of removing the foreign matter is improved and the time required for the foreign matter removing process is shortened.

  The contents disclosed in each of the above embodiments and modifications can be executed in appropriate combination.

DESCRIPTION OF SYMBOLS 1 Grinding device 4 Holding table 4a Holding surface 4b Recessed part 4c Center part 4e Outer peripheral edge 4f Radial area 10 Foreign material removal tool 11 Moving part 12 Circular whetstone part 12a Whetstone main body 12b Whetstone holding part 12c Outer periphery 12d Contact part 13 Circular whetstone part holding part Co Rotation axis Dw Grindstone outer diameter Rt Holding surface radius W Workpiece W1 Device area W2 Outer peripheral area W3 Recessed part W4 Ring-shaped reinforcing part Wa Surface Wb Back

Claims (3)

A holding surface formed of a circular ceramic for holding a workpiece; the holding surface is concavely curved from the center toward the outer periphery; and the holding table of the holding table is driven to rotate about the center of the holding surface as a rotation axis. A foreign matter removal tool for removing foreign matter from a holding surface,
A circular grindstone portion made of a disc-shaped grindstone formed with an outer diameter equivalent to the radius of the holding surface of the holding table; and the circular grindstone portion between the center of the holding surface of the holding table and the outer peripheral edge. A moving portion positioned in the radius region, and a circular grindstone holding portion that is rotatably connected to the lower end of the moving portion and holds the circular grindstone portion below,
A foreign matter removing tool, wherein a material of a surface of the circular grindstone portion that contacts the holding surface of the holding table is made of a material having a bending strength smaller than a bending strength of ceramic of the holding surface.   2. The foreign matter removing tool according to claim 1, wherein a surface of the circular grindstone portion that comes into contact with the holding table is formed of ceramic or resin having a bending strength of JIS R1601 of 350 MPa or less. A holding surface having a circular shape for holding a workpiece, the holding surface being concavely curved from the center toward the outer peripheral edge, and a foreign object from the holding surface of the holding table that is driven to rotate about the center of the holding surface as a rotation axis. A foreign matter removing method for removing
A foreign matter removing tool positioning step for positioning the circular grindstone part of the foreign matter removing tool according to claim 1 or 2 in a radial region between a center and an outer peripheral edge of the holding surface;
After performing the foreign matter removal tool positioning step, the foreign matter removal step of removing foreign matter on the holding surface by rotating at least one of the holding table or the circular grindstone portion;
A foreign matter removing method comprising:

Images