JP6858529B2 - Holding table holding surface forming method, grinding equipment and grinding wheel - Google Patents

Description

The present invention relates to a method for forming a holding surface of a holding table, a grinding device, and a grinding wheel.

In a holding table of a grinding device that grinds the surface of a wafer, the holding surface is ground by the grinding wheel in order to make the grinding surface of the grinding wheel parallel to the holding surface of the holding table (self-grinding (for example, Patent Document). 1)).

The holding table is composed of a porous plate and a frame body that seals the outer surface and the lower surface of the porous plate. The frame body is formed with a recess having a bottom surface and an inner side surface for accommodating the porous plate, and the lower surface of the porous plate and the bottom surface of the recess are adhered by an adhesive. In addition, the bottom surface is configured to be able to communicate with the suction source. By communicating the bottom surface with the suction source, a negative pressure is generated on the holding surface, and the wafer can be sucked and held on the holding surface.

When grinding the holding surface, in order to prevent grinding debris from being sucked into the holding surface, grinding is performed without communicating the holding surface (bottom surface of the recess) with the suction source. That is, the holding surface is ground without the porous plate being sucked. Specifically, in Patent Document 1, the holding surface is ground while ejecting water from the holding surface so that the porous plate is not clogged with grinding debris.

Japanese Unexamined Patent Publication No. 2008-114336

By the way, the lower surface of the porous plate and the bottom surface of the concave portion are made accurate by machining, but there is a slight gap between the porous plate and the frame body. Since the lower surface of the porous plate and the bottom surface of the recess are adhered by the adhesive that has entered the gap, if a suction force is generated on the holding surface, the adhesive is slightly deformed and the holding surface sinks. Congestion may occur.

As described above, the shape of the porous plate differs depending on the presence or absence of the suction force between the case of grinding the holding surface and the case of grinding the wafer W. Therefore, in wafer grinding after grinding the holding surface, an extra grinding step is required to correct the shape.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for forming a holding surface of a holding table, a grinding device, and a grinding wheel, which can eliminate the need for modifying the shape of a wafer after self-grinding. Let's do it.

In the method for forming a holding surface of a holding table according to one aspect of the present invention, a grinding wheel in which a waha sucked and held by the holding surface of the holding table is annularly arranged and a grinding wheel is rotated is rotated and fed toward the holding surface. This is a method of forming a holding table holding surface in which the holding surface of the holding table is ground by the grinding surface of a grinding wheel to make the holding surface parallel to the ground surface. a porous plate with a surface, a frame body having a recess for accommodating the porous plate, and a through-hole communicating to the suction source through the bottom of the recess, when grinding the holding surface in the grinding wheel, the through-hole Is not connected to the suction source, but the holding surface is closed and the through hole is communicated with the suction source. Grinding the holding surface while holding the holding surface with a force of magnitude.

The grinding device according to one aspect of the present invention is a grinding device that grinds a wafer that is sucked and held by the holding surface of the holding table with a grinding wheel on which a grinding grind is arranged in an annular shape, and the upper surface of the holding table is the holding surface. It is composed of a porous plate, a frame body having a recess for accommodating the porous plate, and an adhesive that adheres the lower surface of the porous plate and the bottom surface of the frame body. when grinding the support surface, do not connect the through-hole to a suction source, pressing the grinding wheel on the holding surface with a force above the grinding load wafers pressing the holding surface by suction force by the suction source to hold the wafer in holding surface ground holding surface while imparting grinding load to the adhesive.

According to these configurations, the holding surface is ground while the grinding wheel presses the holding surface with a force equal to or greater than the force with which the wafer presses the holding surface when grinding the wafer. Therefore, the holding surface can be ground in consideration of the suction force when the wafer is sucked and held on the holding surface. Therefore, even if there is a gap between the lower surface of the porous plate and the bottom surface of the recess, the holding surface can be ground in a state in which the porous plate is deformed according to the gap (a state in which the gap is corrected). That is, when grinding the holding surface, the shape of the holding surface at the time of wafer grinding is reproduced. In this way, by matching the state of the holding surface (shape of the holding surface) at the time of wafer grinding and at the time of self-grinding, it is possible to appropriately grind the holding surface. As a result, it is possible to eliminate the need to modify the shape of the wafer after self-grinding.

The grinding wheel of one aspect of the present invention is a grinding wheel used in the above-mentioned method for forming a holding surface of a holding table or a grinding device, and the holding surface is pressed by the grinding wheel by changing the grinding particle size of the grinding wheel. Adjust the force to grind the holding surface.

According to the present invention, it is possible to eliminate the need to modify the shape of the wafer after self-grinding.

It is a perspective view of the grinding apparatus to which the holding surface forming method of the holding table which concerns on this embodiment is applied. It is a schematic diagram at the time of grinding a wafer by the grinding apparatus which concerns on this embodiment. It is a schematic diagram at the time of grinding a holding surface by the grinding apparatus which concerns on this embodiment.

Hereinafter, the grinding apparatus of this embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a grinding apparatus to which the holding surface forming method of the holding table according to the present embodiment is applied. Further, the grinding device is not limited to the device configuration dedicated to grinding as shown in FIG. 1, and for example, a fully automatic type machining in which a series of machining such as grinding, polishing, and cleaning is performed fully automatically. It may be incorporated into the device.

As shown in FIG. 1, the grinding device 1 is configured to grind the wafer W held on the holding table 20 by using a grinding wheel 46 in which a large number of grinding wheels 47 are arranged in an annular shape. The wafer W is carried into the grinding apparatus 1 with a protective tape (not shown) attached, and is held on the holding table 20. The wafer W may be a plate-shaped member to be ground, a semiconductor wafer such as silicon or gallium arsenide, an optical device wafer such as ceramic, glass, or sapphire, or an as before device pattern formation. It may be a slice wafer.

A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 10 of the grinding device 1, and this opening is covered with a moving plate 11 movable together with the holding table 20 and a bellows-shaped waterproof cover 12. ing. Below the waterproof cover 12, a ball screw type advancing / retreating means (not shown) for moving the holding table 20 in the X-axis direction is provided. The holding table 20 is connected to a rotating means (not shown), and is configured to be rotatable by driving the rotating means. Further, on the upper surface of the holding table 20, a holding surface 21a for sucking and holding the wafer W is formed by a porous porous material.

Specifically, the holding table 20 is a porous chuck that sucks and holds the wafer W, and is configured by attaching a disc-shaped porous plate 21 to a frame body 22 as a body (see FIG. 2). The porous plate 21 is a porous material such as ceramics, and fine pores for suction are formed throughout. The frame body 22 has a circular shape having a diameter larger than that of the porous plate 21, and a circular recess 23 for accommodating the porous plate 21 is formed in the center. The inner surface of the circular recess 23 is formed to have the same inner diameter as the outer diameter of the porous plate 21. Further, the depth of the circular recess 23 is formed to be substantially the same as the thickness of the porous plate 21.

A through hole 22a connected to the suction source 25 is formed at the center of the bottom surface 23a (bottom portion) of the circular recess 23. The upper end of the through hole 22a is connected to the circular hole 22b exposed on the bottom surface 23a. Further, on the bottom surface 23a of the circular recess 23, a plurality of (two in FIG. 2) annular grooves 22c are formed around the circular hole 22b. Each annular groove 22c is connected to the through hole 22a through a communication passage 22d formed in the frame body 22.

The porous plate 21 is fitted in the circular recess 23, and the lower surface of the porous plate 21 and the bottom surface 23a of the circular recess 23 are adhered to each other by the adhesive A. As a result, the frame body 22 and the porous plate 21 are integrated, and a holding surface 21a on which the upper surface of the porous plate 21 is exposed is formed on the holding table 20. Although details will be described later, the holding surface 21a is formed in a conical shape with the rotation center of the holding table 20 as the apex and the outer circumference slightly lower (see FIG. 2).

A suction source 25 is connected to the through hole 22a via a valve 24, and when the valve 24 is opened, the suction source 25 and the through hole 22a are communicated with each other. As a result, a negative pressure is generated on the holding surface 21a, and the wafer W can be sucked and held on the holding surface.

The column 15 on the base 10 is provided with a grinding feed means 30 for grinding and feeding the grinding means 40 in a direction (Z-axis direction) for approaching and separating from the holding table 20. The grinding feed means 30 has a pair of guide rails 31 arranged on the column 15 parallel to the Z-axis direction, and a motor-driven Z-axis table 32 slidably installed on the pair of guide rails 31. .. Nut portions (not shown) are formed on the back surface side of the Z-axis table 32, and a ball screw 33 is screwed into these nut portions. The ball screw 33 is rotationally driven by the drive motor 34 connected to one end of the ball screw 33, so that the grinding means 40 is moved along the guide rail 31 in the Z-axis direction.

The grinding means 40 is attached to the front surface of the Z-axis table 32 via the housing 41, and is configured to rotate the grinding wheel 46 around the central axis by the spindle unit 42. The spindle unit 42 is a so-called air spindle, and rotatably supports the spindle shaft 44 inside the casing via high-pressure air.

A mount 45 is connected to the tip of the spindle shaft 44, and a grinding wheel 46 in which a large number of grinding wheels 47 are arranged in an annular shape is mounted on the mount 45. The grinding wheel 47 according to the present embodiment is configured by, for example, bonding diamond abrasive grains having an abrasive particle size of 2 μm to 10 μm with a vitrified bond. The grinding wheel 47 is not limited to this, and the diamond abrasive grains may be formed by solidifying with a binder such as a metal bond or a resin bond.

Further, the grinding device 1 is provided with a control means 90 that controls each part of the device in an integrated manner. The control means 90 is composed of a processor, a memory, and the like that execute various processes. The memory is composed of one or a plurality of storage media such as ROM (Read Only Memory) and RAM (Random Access Memory) depending on the intended use.

In the grinding device 1, the wafer W is thinned to a predetermined thickness by rotating the grinding wheel 47 arranged on the grinding wheel 46 while pressing it against the upper surface of the wafer W. At this time, the grinding means 40 grinds the wafer W while the grinding feed amount is controlled by the control means 90. Although the details will be described later, when the holding surface 21a is ground by the grinding wheel 47, the control means 90 holds the grinding wheel 47 with a grinding load equal to or greater than the force with which the wafer W presses the holding surface 21a when grinding the wafer W. The grinding feed amount, grinding feed speed, and the like (other, for example, the rotation speed of the grinding wheel) of the grinding feed means 30 are controlled so as to be pressed against the 21a.

Further, in the grinding device 1, the grinding surface 47a of the grinding wheel 47 and the holding surface 21a of the holding table 20 are parallel to each other, such as when the grinding wheel 46 is replaced or after the wafer W has been ground a predetermined number of times. A so-called self-grinding is performed in which the holding surface 21a is ground on the grinding surface 47a of the grinding wheel 47. By leveling the grinding surface 47a and the holding surface 21a in parallel, it is possible to appropriately grind the wafer W.

Further, in the self-grinding in which the holding surface 21a is ground by the grinding wheel 47, grinding is performed without communicating the holding surface 21a with the suction source 25 so that grinding debris does not mix with the holding surface 21a during grinding. Specifically, the holding surface 21a is ground by the grinding wheel 47 with the valve 24 closed. That is, the holding surface 21a is not pulled down by the suction force.

On the other hand, when the wafer W is sucked and held by the holding surface 21a to grind the wafer W, the valve 24 is opened and the holding surface 21a is communicated with the suction source 25. Further, the holding surface 21a is entirely covered with a wafer W. That is, since the holding surface 21a is closed by the wafer W, the wafer W is ground in a state where the holding surface 21a is pulled downward by the suction force.

By the way, although the lower surface of the porous plate 21 and the lower surface 23a of the circular recess 23 have been machined to be accurate, there is a slight gap between the porous plate 21 and the frame body 22. Further, as described above, the lower surface of the porous plate 21 and the bottom surface 23a of the circular recess 23 are adhered to each other by the adhesive A. The adhesive A is filled so as to fill a slight gap between the porous plate 21 and the frame body 22, and then cured to integrally fix (adhere) the porous plate 21 and the frame body 22.

However, the adhesive A has a slight elasticity even after being cured. Therefore, the adhesive A is slightly crushed by the suction of the holding surface 21a. That is, when grinding the wafer W, the processing is performed in a state where the holding surface 21a is sunk downward with respect to the frame body 22 by the amount that the adhesive A is crushed.

As described above, the shape of the porous plate 21 (holding surface 21a) differs depending on the presence or absence of suction force between the case of grinding the holding surface 21a and the case of grinding the wafer W. Therefore, even if the holding surface 21a is ground and the holding surface 21a and the ground surface 47a are leveled in parallel, when the wafer W is subsequently ground, an extra grinding step (in-plane thickness difference) is required to correct the shape. Correction) is required.

Therefore, the present inventor has conceived to reproduce the shape of the holding surface during wafer grinding by increasing the grinding load during self-grinding as compared with wafer grinding. Specifically, in the present embodiment, self-grinding is performed with a grinding load equal to or greater than the force with which the wafer W presses the holding surface 21a when grinding the wafer W.

According to this configuration, the holding surface grinding is performed in consideration of the suction force when the wafer W is sucked and held by the holding surface 21a. Therefore, even if there is a gap between the lower surface of the porous plate 21 and the bottom surface 23a of the circular recess 23, the holding surface 21a can be ground with the gap corrected. That is, when grinding the holding surface 21a, the shape of the holding surface at the time of wafer grinding is reproduced. In this way, by matching the shapes of the holding surface 21a during wafer grinding and self-grinding, it is possible to appropriately grind the holding surface 21a. As a result, it is possible to eliminate the need to modify the shape of the wafer W after self-grinding.

Next, a method of forming a holding surface of the holding table according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic view of grinding a wafer with the grinding apparatus according to the present embodiment. FIG. 3 is a schematic view when the holding surface is ground by the grinding apparatus according to the present embodiment.

First, a case where the wafer W is ground with the grinding wheel 47 will be described. As shown in FIG. 2, the wafer W is suction-held on the holding table 20. Specifically, the wafer W is placed so as to cover the entire holding surface 21a, and the holding surface 21a is in a state of being closed by the wafer W. Further, when the valve 24 is opened, the through hole 22a is communicated with the suction source 25. The porous plate 21 is sucked into the suction source 25 through the circular hole 22b, the plurality of annular grooves 22c, the communication passage 22d, and the like. As a result, a negative pressure is generated on the holding surface 21a, and the wafer W is sucked and held on the holding surface 21a.

As described above, since the holding surface 21a is formed in a conical shape that is slightly inclined downward from the center toward the outer periphery, the wafer W is attracted to the holding surface 21a and follows the shape of the holding surface 21a. It becomes a gently sloping conical shape.

In this way, when the wafer W is sucked and held by the holding surface 21a, the porous plate 21 (holding surface 21a) is subjected to the suction force of the suction source 25 from the holding surface 21a to the bottom surface 23a (bottom portion) of the frame body 22. The force to hold down with the wafer W is working in the direction toward (downward). This force is defined as the pressing force (suction force) F1.

By this pressing force F1, the porous plate 21 is pressed downward by the wafer W, and the adhesive A is slightly crushed. As a result, the holding surface 21a sinks (deforms) with respect to the upper surface 22e of the frame body 22 by the amount of deformation of the adhesive A. That is, the holding surface 21a sinks toward the bottom surface 23a of the frame body 2.

Further, the holding table 20 is positioned below the grinding means 40. At this time, the rotation axis of the holding table 20 is positioned at a position eccentric from the rotation axis of the grinding wheel 47. Further, the inclination of the rotating shaft of the holding table 20 is adjusted by an inclination adjusting mechanism (not shown) so that the grinding surface 47a and the holding surface 21a of the grinding wheel 47 are parallel to each other.

Then, as the holding table 20 is rotated, the grinding means 40 is lowered (grinding feed) toward the holding surface 21a by the grinding feed means 30 while rotating the grinding wheel 47. The grinding surface 47a of the grinding wheel 47 is brought into contact with a radial portion extending from the center of the wafer W to the outer periphery in an arc shape.

As a result, the grinding wheel 47 and the wafer W are brought into rotational contact, and the surface of the wafer W is ground. In particular, during wafer grinding, the holding surface 21a is in a state of receiving a predetermined grinding load F2 from the grinding means 40 in addition to the pressing force F1 described above. That is, the holding surface 21a is pressed by the wafer W by the force of the pressing force F1 + the grinding load F2 during the wafer grinding.

Next, a method of forming a holding surface of the holding table 20 will be described. As shown in FIG. 3, when the holding surface 21a is ground by the grinding wheel 47, the valve 24 is closed and the suction source 25 and the holding surface 21a are not communicated with each other. Therefore, a force corresponding to the pressing force F1 shown in FIG. 2 is not applied to the holding surface 21a. Further, similarly to FIG. 2, the holding table 20 is positioned below the grinding means 40, and the inclination of the holding table 20 is adjusted so that the holding surface 21a and the grinding surface 47a are parallel to each other.

Then, as the holding table 20 is rotated, the grinding means 40 is lowered (grinding feed) toward the holding surface 21a by the grinding feed means 30 while rotating the grinding wheel 47. The grinding surface 47a of the grinding wheel 47 is brought into contact with a radial portion extending from the center of the holding surface 21a to the outer periphery in an arc shape.

As a result, the grinding wheel 47 and the holding surface 21a are brought into rotational contact, and the holding surface 21a is ground (self-grinded). In particular, at the time of grinding the holding surface, the grinding means 40 presses the grinding wheel 47 against the holding surface 21a with a grinding load F3 equal to or greater than the force with which the wafer W presses the holding surface 21a when grinding the wafer W.

Specifically, in the grinding means 40, in addition to the attractive force of the holding surface 21a during wafer grinding (pressing pressure F1 described above), the holding surface is held by the grinding wheel 47 with a force having a magnitude equal to or greater than the grinding load F2 during wafer grinding. Grinding is performed while holding down 21a. That is, the grinding load F3 at the time of grinding the holding surface is adjusted in the grinding feed amount and the grinding feed speed so that the relationship of F3 ≧ F1 + F2 is established.

In this way, when grinding the holding surface, the suction force (pressing pressure F1) of the holding surface 21a during wafer grinding is taken into consideration, and the grinding load F3 is increased by the amount of the suction force as compared with the grinding load F2 during wafer grinding. I'm raising it. As a result, when grinding the holding surface, even if the valve 24 is closed and no suction force is generated on the holding surface 21a, the force equal to or greater than the force with which the wafer W presses the holding surface 21a is sufficient. The holding surface 21a can be pressed by the grinding wheel 47.

Therefore, even in the case of self-grinding in which the grinding process is performed without sucking the holding surface 21a, it is possible to reproduce the state in which the suction force is generated on the holding surface 21a. Therefore, the porous plate 21 is pressed downward by the wafer W, and the adhesive A is slightly crushed. As a result, the holding surface 21a sinks with respect to the upper surface 22e of the frame body 22 by the amount of the deformation of the adhesive A. Include. That is, the holding surface 21a sinks toward the bottom surface 23a of the frame body 2.

Therefore, even if there is a gap between the lower surface of the porous plate 21 and the bottom surface 23a of the circular recess 23, the holding surface 21a is ground in a state in which the porous plate is deformed by the amount of the gap (a state in which the gap is corrected). be able to. That is, when grinding the holding surface 21a, the shape of the holding surface at the time of wafer grinding is reproduced. In this way, by matching the state of the holding surface (shape of the holding surface) at the time of wafer grinding and at the time of self-grinding, it is possible to appropriately grind the holding surface 21a. As a result, it is possible to eliminate the need to modify the shape of the wafer W after self-grinding.

In the present embodiment, the grinding load F3 at the time of grinding the holding surface is adjusted by controlling the grinding feed amount and the grinding feed speed by the control means 90, but the present invention is not limited to this configuration. The grinding load F3 may be adjusted in any way as long as self-grinding can be performed with a force of F1 + F2 or more described above. For example, the grinding load F3 may be adjusted by controlling the rotation speed of the grinding wheel 46 and the rotation speed of the holding table 20 with the control means 90. In addition, the grinding load F3 may be adjusted not only by the control means 90 but also by appropriately changing the grinding particle size of the grinding wheel 47, the type of the binder, the concentration degree and the coupling degree of the grinding wheel 47 as appropriate.

Here, the degree of concentration of the grinding wheel 47 represents the amount (density) of the abrasive grains contained in the grinding wheel 47. Further, the degree of coupling of the grinding wheel 47 represents the hardness of the grinding wheel 47. For example, if the degree of concentration is lowered, the holding surface 21a can be made difficult to scrape. Increasing the degree of bonding makes it difficult for the abrasive grains to fall off from the binder, and as a result, the holding surface 21a can be made difficult to scrape.

Further, the degree of scraping of the holding surface 21a can also be adjusted by changing the grinding grain size of the grinding wheel 47. For example, if the grinding wheel particle size of the grinding wheel 47 is reduced, the holding surface 21a becomes difficult to scrape. On the other hand, if the grinding wheel diameter of the grinding wheel 47 is increased, the holding surface 21a is easily scraped. By making the holding surface 21a difficult to scrape in this way, it is possible to further increase the grinding load. Therefore, when adjusting (increasing) the grinding load F3 by changing the composition of the grinding wheel 47, it is preferable to reduce the abrasive particle size, decrease the concentration, and / or increase the coupling degree.

Further, in the present embodiment, the same grinding wheel 46, that is, the grinding wheel 47 having the same grinding grain size is used to perform the grinding process at the time of wafer grinding and at the time of holding surface grinding, respectively. Not limited to. The grinding wheel 46 (abrasive particle size of the grinding wheel 47) may be different (changed) between the wafer grinding and the holding surface grinding. In this case, it is preferable that the grinding wheel diameter of the grinding wheel 47 during holding surface grinding is smaller than that during wafer grinding. As a result, the grinding load during holding surface grinding can be increased as compared with that during wafer grinding.

Moreover, although the present embodiment and the modified example have been described, as another embodiment of the present invention, the above-described embodiment and the modified example may be combined in whole or in part.

Further, the embodiment of the present invention is not limited to the above-described embodiment, and may be variously modified, replaced, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by the advancement of technology or another technology derived from it, it may be carried out by using that method. Therefore, the scope of claims covers all embodiments that may be included within the scope of the technical idea of the present invention.

Further, in the present embodiment, the configuration in which the present invention is applied to the grinding apparatus has been described, but it can be applied to other apparatus capable of self-grinding.

As described above, the present invention has an effect that it is not necessary to modify the shape of the wafer after self-grinding, and in particular, a method for forming a holding surface of a holding table used in a grinding device, a grinding device, and grinding. Useful for wheels.

1 Grinding device 20 Holding table 21 Porous plate 21a Holding surface 22 Frame body 22a Through hole 23 Circular recess (recess)
24 Valve 25 Suction source 46 Grinding wheel 47 Grinding whetstone 47a Grinding surface A Adhesive F1 Suction force (pressing pressure)
F2, F3 Grinding load W wafer

Claims (3)

The holding of the holding table is performed in a grinding device that grinds the waiha that is sucked and held by the holding surface of the holding table by rotating a grinding wheel in which a grinding wheel is arranged in an annular shape and grinding and feeding toward the holding surface. A method for forming a holding surface of a holding table in which a surface is ground by the grinding surface of the grinding wheel to make the holding surface parallel to the ground surface.
The holding table includes a porous plate whose upper surface is the holding surface, a frame having a recess for accommodating the porous plate, and a through hole that penetrates the bottom of the recess and communicates with a suction source.
When grinding the holding surface with the grinding wheel, the through hole is not connected to the suction source, but the holding surface is closed and the through hole is communicated with the suction source by the suction force of the suction source. A holding table that grinds the holding surface while the grinding wheel holds the holding surface with a force greater than or equal to the force of pressing with a wafer that covers the holding surface in the direction from the holding surface toward the bottom of the frame. Holding surface forming method. A grinding device that grinds a wafer that is sucked and held on the holding surface of a holding table with a grinding wheel in which grinding wheels are arranged in an annular shape.
The holding table is composed of a porous plate whose upper surface is holding surface, a frame body having a recess for accommodating the porous plate, the adhesive for bonding the bottom surface of the lower surface and the frame body of the porous plate,
A suction source is connected to the porous plate, and a suction source is connected to the porous plate.
When grinding the holding surface with the grinding wheel , the through hole is not connected to the suction source, but the wafer is held by the holding surface, and the suction force of the suction source causes the wafer to hold the holding surface or more. while the the grinding grindstone grinding load is applied to the adhesive to the grinding pressing load to the holding surface grinding apparatus characterized that you grinding the holding surface. The grinding wheel used in the holding surface forming method of the holding table according to claim 1 or the grinding apparatus according to claim 2.
A grinding wheel characterized in that the holding surface is ground by adjusting the force of pressing the holding surface with the grinding wheel by changing the grinding particle size of the grinding wheel.

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