JP2020142334A - Holding means and processing device - Google Patents

Abstract

To polish a work-piece into a uniform thickness.SOLUTION: By using holding surface deforming means 75 in which are arranged a center part 750, a first ring part 751, a second ring part 752, a plurality of piezoelectric actuators 755 comprising contact surfaces 755a for pushing up the above three parts respectively from below, and a guide part 756 comprising grooves 756a and balls 756b that assist upward/downward movements of the three parts so that the three parts can move up and down in a direction perpendicular to a holding surface 71a of the table 70, lengths of the piezoelectric actuators 755 are varied and shapes of the table 70 and of a work-piece W held on the holding surface 71a of the table 70 are varied by pushing up the three parts, and then the polishing means 4 is moved down toward the table 70 so that a polishing pad 44 provided in polishing means 4 is contacted with a surface Wa of the work-piece W, so as to perform polishing processing.SELECTED DRAWING: Figure 5

Description

The present invention relates to a holding means for holding a work piece when the work piece is machined.

In the manufacture of wafers, the wafer is ground with a grinding wheel to make it thinner, and then polished with a polishing pad to remove the grinding marks formed on the wafer and make it uniform in thickness to enhance the bending strength of the wafer. are doing. If the material of the work piece is different from the usual one, or if multiple work pieces are continuously polished, the polishing pad will be severely worn and the work piece will be flat after polishing. do not become. Therefore, as in the invention disclosed in Patent Document 1, the shape of the polished surface of the polishing pad is adjusted.

Further, for example, in CMP polishing or dry polishing in which a polishing pad is brought into contact with the polishing pad so as to cover the upper surface of the workpiece held by the holding means, the center of the workpiece is easily polished. Therefore, the shape of the lower surface of the polishing pad is deformed from a flat shape to a concave shape, and the inclination relationship between the rotation axis of the holding means and the rotation axis of the polishing pad is changed to flatten the workpiece. ..

JP-A-2016-179513

However, since the shape of the polished surface is adjusted by scraping the polished surface, the polishing pad is consumed and uneconomical, and there is also a problem that the shape adjustment takes time.
Further, in a processing apparatus for processing an workpiece held on a table with a processing tool attached, there is also a problem that the processing result when polishing using the polishing device changes depending on the distance between the upper surface of the table and the processing tool. is there.
As described above, in the polishing apparatus, there is a problem to be solved that the wafer after polishing has a uniform thickness by an economical and efficient method.

The present invention is a holding unit having a holding surface for holding a work piece, and supports a table having the holding surface on the upper surface, a communication means for communicating the holding surface with a suction source, and the table from below. The holding surface deforming means includes a holding surface deforming means for deforming the holding surface, and the holding surface deforming means includes a columnar central portion whose center is positioned on an axis passing through the center of the holding surface, and a first surrounding the central portion. A ring portion, a second ring portion that surrounds the first ring portion, a cylinder portion that surrounds the second ring portion, a base that closes the lower end of the cylinder portion, and an upper surface of the base. Arranged between the lower surface of the central portion, between the upper surface of the base and the lower surface of the first ring portion, and between the upper surface of the base and the lower surface of the second ring portion. A holding unit including a piezoelectric actuator and a guide portion that allows each of the central portion, the first ring portion, and the second ring portion to be raised and lowered in a direction perpendicular to the holding surface. Is.

Further, in the guide portion, the guide portion is arranged at at least three positions at an equal angle with the center of the holding surface as the center, and the central portion and the first ring portion, the first ring portion and the second ring are provided. A portion, a groove formed so as to face each of the opposite side surfaces of the second ring portion and the tubular portion, and a ball or roller housed in the groove and movable in the vertical direction are provided. Is desirable.

Further, the present invention is a processing apparatus provided with the above-mentioned holding unit, which supports a power supply unit that supplies a DC voltage to the piezoelectric actuator, the piezoelectric actuator that supports the central portion, and the first ring portion. A control means for controlling the voltage supplied to each of the piezoelectric actuator and the piezoelectric actuator that supports the second ring portion is provided, the voltage is controlled by the control means, and the length of the piezoelectric actuator is determined. By changing the height of the central portion, the first ring portion, and the second ring portion, the shape of the holding surface is deformed, and the workpiece held by the holding surface is processed by the processing tool of the processing means. It is a processing device that processes with.

In the holding unit according to the present invention, since the central portion, the first ring portion and the second ring portion can be individually raised and lowered to change the shape of the holding surface, the object to be held and processed on the holding surface. The shape of the upper surface of the work piece can be adjusted.

On the side surface where the central part and the first ring part, the first ring part and the second ring part, and the second ring part and the cylinder part face each other, a groove formed facing each other and a groove housed in the groove in the vertical direction When equipped with a movable ball or roller, the three balls or rollers rotate while sliding in contact with the groove, so that the central portion 750, the first ring portion, and the second ring portion can be smoothly moved up and down. can do.

In the processing apparatus provided with the holding unit, the shape of the upper surface of the workpiece can be adjusted and processed by adjusting the shape of the holding surface, so that the adjustment can be performed in a short time and the machining tool can be used. There is no need to adjust. In addition, when processing a single workpiece, the thickness of the workpiece is measured to change the shape of the holding surface before the preset time elapses, and the machining is performed in the remaining time. It is also possible to form the workpiece into a desired shape.

It is a perspective view which shows the whole processing apparatus. It is sectional drawing which saw the holding unit from the side. It is an exploded perspective view of the holding surface deforming means viewed from diagonally above, and in particular, (a) represents a columnar central portion, and (b) represents a ring-shaped first ring portion surrounding the central portion. c) represents a ring-shaped second ring portion that surrounds the first ring portion, and (d) represents a ring-shaped tubular portion that surrounds the second ring portion. It is a perspective view which shows the piezoelectric actuator. It is sectional drawing which looked at the state of deforming the holding surface of a table by using the holding surface deformation means from the side. It is sectional drawing which saw from the side which the holding surface of an inclined table is deformed by using the holding surface deformation means.

1 Configuration of Processing Device The processing device 1 shown in FIG. 1 is a processing device that polishes the surface Wa of the workpiece W held on the table 70 by using the polishing means 4. Hereinafter, the configuration of the processing apparatus 1 will be described.

As shown in FIG. 1, a base 10 is extended in the Y-axis direction in the processing apparatus 1, and a column 12 is erected on the + Y direction side of the base 10.

The processing apparatus 1 is provided with a control means 2. The workpiece W can be polished by driving various means for polishing using the control means 2.

On the side surface of the column 12 of the processing apparatus 1 on the −Y side, a polishing means 4 and a Z-axis direction moving means 5 for moving the polishing means 4 up and down are provided. The polishing means 4 is provided with a spindle 40, a spindle housing 41 that surrounds the spindle 40, and a motor 42 that rotates the spindle 40 around a rotation shaft 45 in the Z-axis direction. A mount 43 is connected to the lower end of the spindle 40, and a polishing pad 44 is fixed to the lower surface side of the mount 43. The polishing pad 44 is composed of a disk 440 connected to the lower surface of the mount 43 and a polishing member 441 arranged at the lower end of the disk 440. At the time of polishing, the polishing member 441 of the polishing pad 44 comes into contact with the surface Wa of the workpiece W, and the surface Wa of the workpiece W is polished. By driving the spindle 40 with the motor 42, when the spindle 40 rotates, the mount 43 and the polishing pad 44 connected to the spindle 40 rotate about the rotation shaft 45 as well. There is.

The polishing member 441 is made of, for example, a non-woven fabric such as felt, and a through hole (not shown) through which a slurry (polishing liquid containing free abrasive grains) is passed is formed in the central portion thereof. Further, inside the spindle 40, a slurry flow path 30 having an inlet 30a connected to a slurry supply means 3 provided above the spindle 40 and an outlet 30b connected to a polishing pad 44 is provided in the Z-axis direction. It is formed to extend. During the polishing process, the slurry supplied from the inlet 30a to the slurry flow path 30 by the slurry supply means 3 flows out from the outlet 30b of the slurry flow path 30 to the polishing pad 44, passes through the through hole of the polishing member 441, and is a polishing member. It will reach the contact portion between the 441 and the workpiece W.

The slurry is supplied to the contact portion between the polishing member 441 and the workpiece W using the slurry supply means 3 or the like as described above, for example, when the polishing process to be performed is CMP polishing. On the other hand, it is not performed in the case of dry polishing.

The Z-axis direction moving means 5 includes a ball screw 50 having a rotation axis 55 in the Z-axis direction, a pair of guide rails 51 arranged in parallel with the ball screw 50, and a ball screw 50 connected to the upper end of the ball screw 50. A motor 52 that rotates about 55 as an axis, an elevating plate 53 in which an internal nut is screwed into a ball screw 50 and a side portion is in sliding contact with a guide rail 51, and a holder 54 connected to the elevating plate 53 are provided. Further, the polishing means 4 is supported by the holder 54. By driving the ball screw 50 using the motor 52, when the ball screw 50 rotates about the rotation shaft 55, the elevating plate 53 is guided by the guide rail 51 and moves up and down in the Z-axis direction. The holder 54 connected to the elevating plate 53 and the polishing means 4 held by the holder 54 move up and down in the Z-axis direction.

As shown in FIG. 1, a holding unit 7 for holding the workpiece W is arranged near the center of the base 10 of the processing apparatus 1. The holding unit 7 is provided with a table 70 having a suction portion 71 formed of a porous member or the like and a frame body 72 surrounding the suction portion 71, and a workpiece W is placed on the upper surface of the suction portion 71. It is a holding surface 71a to be placed.

As shown in FIG. 2, the holding unit 7 is provided with a suction source 73 and a communication means 74. The communication means 74 is a conduit whose one end is connected to the suction source 73, passes through the inside of the rotary joint 760, and further passes through the inside of the support member 741 that supports the table 70 from below, and is a plurality of conduits inside the support member 741. The other ends of the communicating means 74 branched into the above are connected to the suction portion 71, respectively. With the workpiece W placed on the holding surface 71a of the table 70, a suction source 73 is used to generate a suction force, and the suction force generated by the suction source 73 is transmitted to the suction unit through the communication means 74. By transmitting to the holding surface 71a of 71, the workpiece W can be sucked and held on the table 70.

As shown in FIGS. 2 and 3 (a) to 3 (d), the holding unit 7 is provided with the holding surface deforming means 75 so as to support the table 70 from below via the support member 741. ing. The holding surface deforming means 75 includes a columnar central portion 750 whose center is positioned on a shaft 765 passing through the center of the holding surface 71a (same as the rotation shaft 765 of the table 70 described later), and a first portion surrounding the central portion 750. The ring portion 751 of the above, the second ring portion 752 surrounding the first ring portion 751, the tubular portion 753 surrounding the second ring portion 752, and the base 754 that closes the lower end of the tubular portion 753 are arranged. It is installed. The shapes of the first ring portion 751, the second ring portion 752, and the tubular portion 753 are hollow cylindrical shapes, respectively.

Spacing between the central portion 750 and the first ring portion 751, between the first ring portion 751 and the second ring portion 752, and between the second ring portion 752 and the tubular portion 753, respectively. D1, D2, and D3 are provided.

As shown in FIG. 2, the upper surface 750a of the central portion 750, the upper surface 751a of the first ring portion 751, and the upper surface 752a of the second ring portion 752 are in contact with the lower surface 741b of the support member 741, respectively. The central portion 750, the first ring portion 751, and the second ring portion 752 support the support member 741 from below.

The holding surface deforming means 75 is not limited to the above configuration. For example, the holding surface deforming means 75 includes a third ring portion that surrounds the second ring portion 752 and a fourth ring portion that surrounds the third ring portion. A plurality of rings may be provided, such as a ring portion.

As shown in FIGS. 2 and 4, in the holding surface deforming means 75, between the upper surface 754a of the base 754 and the lower surface 750b of the central portion 750, the upper surface 754a of the base 754 and the lower surface 751b of the first ring portion 751. And between the upper surface 754a of the base 754 and the lower surface 752b of the second ring portion 752, a plurality of first piezoelectric actuators 755A, second piezoelectric actuators 755B, and third piezoelectric actuators, respectively. The 755C is provided. Hereinafter, these are collectively referred to as a piezoelectric actuator 755. The upper surface of the piezoelectric actuator 755 contacts the lower surface 750b of the central portion 750 of the holding surface deforming means 75, the lower surface 751b of the first ring portion 751, and the lower surface 751b of the second ring portion 752, respectively, and brings them from below. It has a rounded contact surface 755a that pushes up.

For example, three first piezoelectric actuators 755A are provided between the upper surface 754a of the base 754 and the lower surface 750b of the central portion 750. For example, as shown in FIG. 4, the three first piezoelectric actuators 755A form an equilateral triangle having the contact surface 755a of each first piezoelectric actuator 755A as three vertices when viewed from above. It is arranged in.

For example, three second piezoelectric actuators 755B are provided between the upper surface 754a of the base 754 and the lower surface 751b of the first ring portion 751. For example, the three second piezoelectric actuators 755B also have three second piezoelectric actuators 755B outside the small equilateral triangle formed by the contact surfaces 755a of the three first piezoelectric actuators 755A when viewed from above. It is arranged so that a large equilateral triangle is formed with the contact surface 755a as an apex.

For example, five third piezoelectric actuators 755C are provided between the upper surface 754a of the base 754 and the lower surface 752b of the second ring portion 752. For example, when the five third piezoelectric actuators 755C are also viewed from above, the contact surfaces of the five third piezoelectric actuators 755C are outside the equilateral triangle formed by the contact surfaces 755a of the second piezoelectric actuator 755B. It is arranged so that a regular pentagon having 755a as an apex is formed. The number of the third piezoelectric actuator does not have to be five. At least three may be arranged so as to form an equilateral triangle.

Between the upper surface 754a of the base 754 and the lower surface 750b of the central portion 750, between the upper surface 754a of the base 754 and the lower surface 751b of the first ring portion 751, and between the upper surface 754a and the second of the base 754. The number and arrangement of piezoelectric actuators 755 provided between the ring portion 752 and the lower surface 752b are not limited to those shown in FIGS. 2 and 4.

By arranging the piezoelectric actuators 755 on the base 754 at equal intervals on the same circumference, the lower surface 750b of the central portion 750, the lower surface 751b of the first ring portion 751, and the second It becomes easy to move the lower surface 752b of the ring portion 752 up and down while keeping it horizontal.

As shown in FIGS. 2 and 3 (a) to 3 (d), the holding unit 7 has a central portion 750, a first ring portion 751, and a second ring portion 752 with respect to the holding surface 71a, respectively. At least three guide portions 756 that can be raised and lowered in the vertical direction are provided. The guide portion 756 includes a side surface 750c of the central portion 750 and an inner side surface 751d of the first ring portion 751, an outer side surface 751c of the first ring portion 751, and an inner side surface 752d of the second ring portion 752. Grooves 756a are formed on the outer side surface 752c of the ring portion 752 and the inner side surface 753d of the tubular portion 753 so as to face each other, and the groove 756a accommodates a ball 756b that can move in the vertical direction. ing.

As shown in FIGS. 3A to 3B, for example, a substantially semi-cylindrical groove 756a is formed on the side surface 750c of the central portion 750, and the inner side surface of the first ring portion 751. A groove 756a having the same shape as the groove 756a is formed in the 751d.

The sphere 756b has, for example, a side surface 750c of the central portion 750 and a first ring portion in a state where a distance D1 is provided between the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751. It is housed so as to be inscribed in the side surface 756c of the groove 756a formed so as to face the inner side surface 751d of the 751. In such a case, since the ball 756b is restrained by the side surface 756c of the groove 756a and cannot move in the direction parallel to the holding surface 71a, the central portion 750 and the first ring portion 751 are blocked by the ball 756b. You can't get close to each other. Therefore, the distance D1 between the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751 takes a constant value, and the direction parallel to the holding surface 71a of the central portion 750 and the first ring portion 751. The relative positional relationship in is fixed.

The sphere 756b has a distance D1 between the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751 as described above, and the sphere 756b has a distance D1 between the sphere 756b and the groove 756a. A small gap may be provided and accommodated in the groove 756a. In such a case, there is room for the sphere 756b to move the space inside the groove 756a in the direction parallel to the holding surface 71a by the amount of the gap, and the central portion 750 and the first sphere 756b move with the movement of the sphere 756b. Since the ring portion 751 can move relatively by the amount of the gap, the central portion 750 and the first ring portion 751 can approach each other by the amount of the gap between the sphere 756b and the groove 756a. However, since the gap is set smaller than the distance D1 between the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751, for example, the side surface 750c and the first side surface of the central portion 750 Even if the inner side surface 751d of the ring portion 751 approaches each other as much as possible, the interval is maintained by subtracting the amount of the gap provided in advance from the initial interval D1 without contacting each other.
That is, when the central portion 750 or the first ring portion 751 moves in the direction perpendicular to the holding surface 71a, it is preferable that a gap is provided so that the sphere 756b can move in the grooves 756a facing each other.

Regarding the positional relationship between the sphere 756b and the groove 756a, the outer side surface 751c of the first ring portion 751, the inner side surface 752d of the second ring portion 752, and the outer side surface 752c of the second ring portion 752. The groove 756a and the sphere 756b arranged on the inner side surface 753d of the tubular portion 753 have the same configuration.

Further, the step generated between the central portion 750, the first ring portion 751 and the second ring portion 752 by being pushed up by the contact surface 755a of the piezoelectric actuator 755 is about 2 μm at the maximum, and therefore, therefore, The depth of the groove 756a shall exceed 2 μm so that the sphere 756b does not exit the groove 756a when the central portion 750, or the first ring portion 751, or the second ring portion 752 is pushed up. The guide portion 756 may be provided with a roller or the like instead of the ball 756b.

As shown in FIGS. 1 and 2, a rotating means 76 composed of a rotary joint 760 and a motor 761 is disposed under the base 754 of the holding surface deforming means 75. The holding surface deforming means 75, which is rotationally driven by the motor 761 and is connected to the rotary joint 760, and the table 70, which is supported by the holding surface deforming means 75 via the support member 741, are centered on the holding surface 71a. It is configured to rotate integrally with the rotation shaft 765 parallel to the Z-axis. The rotating means 76 is surrounded and protected from the side by a tubular casing 792.

The processing apparatus 1 is provided with a power supply unit 90 that supplies a DC voltage to the piezoelectric actuator 755.

The control means 2 described above has a function of controlling the voltage supplied from the power supply unit 90 to the piezoelectric actuator 755. By adjusting the voltages supplied to the piezoelectric actuators 755A, 755B, and 755C, the height of each contact surface 755a can be changed.

As shown in FIG. 1, a Y-axis direction moving means for moving the holding unit 7 for holding the workpiece W in the Y-axis direction on the internal base 11 arranged inside the base 10 of the processing apparatus 1. 8 is provided. In the Y-axis direction moving means 8, a ball screw 80 having a rotation shaft 85 in the Y-axis direction, a pair of guide rails 81 arranged in parallel with the ball screw 80, and a ball screw 80 are rotated around the rotation shaft 85. A motor 82 and a Y-axis base 83 in which an internal nut is screwed into a ball screw 80 and the bottom portion slides in contact with a guide rail 81 and moves in the Y-axis direction are provided. When the ball screw 80 is driven by the motor 82 and rotates around the rotation shaft 85, the Y-axis base 83 is guided by the guide rail 81 and moves in the Y-axis direction, and is supported by the Y-axis base 83 accordingly. The table 70 is configured to move in the Y-axis direction.

The table 70 is surrounded by a cover 77, which is connected to a bellows 78. When the table 70 moves in the Y-axis direction driven by the Y-axis direction moving means 8, the cover 77 moves in the Y-axis direction integrally with the table 70, and the bellows 78 expands and contracts accordingly. ..

As shown in FIG. 2, on the Y-axis base 83, one support column 790 having a fixed height and two tilt changing shafts 791 whose length can be changed (one is located on the inner back side of the center). , Not shown) are arranged on the circumference at intervals of 120 degrees, and a base 754 is connected to the upper part of the support column 790 and the inclination changing shaft 791. The tilt changing shaft 791 is a rod-shaped shaft provided with a mechanism such as a hydraulic type, a pneumatic type, or a motor type, and its length can be controlled. By adjusting the length of the tilt changing shaft 791, the tilts of the holding surface deforming means 75 and the table 70 with respect to the horizontal plane can be changed.

2 Operation of the processing device The operation of the processing device 1 when polishing the workpiece W using the processing device 1 having the above configuration will be described in detail below.

First, as shown in FIG. 5, the workpiece W is placed on the holding surface 71a of the table 70, a suction source 73 is used to generate a suction force, and the generated suction force is transmitted to the communication means 74. The work piece W is sucked and held on the holding surface 71a by transmitting the material to the holding surface 71a. Then, the motor 761 of the rotating means 76 is controlled to rotate the table 70 around the rotating shaft 765.

Next, the spindle 40 is driven by using the motor 42 of the polishing means 4 shown in FIG. 1, and the spindle 40 rotates the rotating shaft 45 in the Z-axis direction. As a result, the mount 43 connected to the lower end of the spindle 40 and the polishing pad 44 fixed to the lower surface side of the mount 43 are rotated.

In a state where the polishing pad 44 is rotating about the rotation shaft 45, the motor 82 of the Y-axis direction moving means 8 is driven to rotate the ball screw 80 around the rotation shaft 85. As a result, the Y-axis base 83 is moved in the Y-axis direction along the guide rail 81, and the Y-axis base 83 is moved so that the polishing pad 44 of the polishing means 4 passes through the rotation shaft 765 of the holding surface 71a of the table 70. Positioned below the polishing pad 44.

At this time, by controlling the tilt changing shaft 791 and changing its length, the tilt of the holding surface deforming means 75 that supports the table 70 and the table 70 from below with respect to the Z-axis direction can be appropriately changed.

Then, the ball screw 50 is rotated around the rotation shaft 55 by using the motor 52 of the Z-axis direction moving means 5, so that the elevating plate 53 is lowered along the guide rail 51 in the −Z direction. Then, the holder 54 connected to the elevating plate 53 and the polishing means 4 supported by the holder 54 descend in the −Z direction, and the polishing member 441 of the rotating polishing pad 44 comes into contact with the rotating workpiece W. .. As a result, the surface Wa of the workpiece W is polished. In the polishing process, the surface Wa of the workpiece W is polished by about 5 μm in the height direction.

During the polishing process, the polishing pad 44 of the polishing means 4 is brought into contact with the surface Wa of the workpiece W, and while the workpiece W is being polished, for example, the workpiece W (not shown) is irradiated with measurement light. The thickness of the workpiece W is measured using a non-contact thickness measuring device that measures the thickness. Before the thickness of the workpiece W reaches the preset finish thickness during the polishing process, the polishing pad 44 is raised by temporarily controlling the Z-axis direction moving means 5 and raising the polishing pad 44 in the + Z direction. Separated from the workpiece W.

After the polishing pad is separated from the workpiece W, the workpiece W is irradiated with measurement light to measure the thickness of the workpiece W at a plurality of points. The measurement position for measuring the thickness of the work piece is at least three points in the radial direction of the work piece, the center of the work piece, the outer peripheral portion, and the position having a radius of 1/2.

After that, when there is a difference in the thickness of the three measured points, the shape of the holding surface 71a is changed in order to eliminate the difference in the thickness of the workpiece W. When deforming the holding surface 71a, first, the power supply unit 90 is controlled to supply a voltage from the power supply unit 90 to the piezoelectric actuator 755. Then, the height of the contact surface 755a is changed by adjusting the voltage supplied to the piezoelectric actuator 755 by the control means 2 to change the length of the piezoelectric actuator 755. As a result, the contact surface 755a of the piezoelectric actuator 755 whose height has changed abuts on the lower surface 750b of the central portion 750, the lower surface 751b of the first ring portion 751, and the lower surface 752b of the second ring portion 752. It is pushed up to change the height of each and deform the holding surface 71a.

For example, when it is desired to transform the shape of the holding surface 71a into a middle-convex shape in which the vicinity of the center of the holding surface 71a protrudes upward as shown in FIG. By moving the first ring portion 751 above the second ring portion 752 and moving it above the ring portion 751, the central portion 750 is in the highest position, and then the first ring 751. Is high and the second ring 752 is located at the lowest position. For that purpose, the value of the voltage applied to the first piezoelectric actuator 755A is changed to raise the height of the contact surface 755a of the first piezoelectric actuator 755A, and the value of the voltage applied to the second piezoelectric actuator 755B is increased. It is changed to increase the height of the contact surface 755a of the second piezoelectric actuator 755B. By increasing the height of the contact surface 755a, the contact surface 755a of the first piezoelectric actuator 755A pushes up the central portion 750 while contacting the lower surface 750b of the central portion 750, and the contact surface of the second piezoelectric actuator 755B. The 755a pushes up the first ring portion 751 while contacting the lower surface 751b of the lower surface of the first ring portion 751. Along with this, the upper surface 750a of the pushed-up central portion 750 pushes up the vicinity of the center of the lower surface 741b of the support member 741, and the upper surface 751a of the first ring portion 751 is located near the center and the peripheral edge of the lower surface 741b of the support member 741. Push up between. Then, the vicinity of the center of the upper surface 741a of the support member 741 pushes up the vicinity of the center of the table 70, and the region between the central portion and the peripheral edge portion of the upper surface 741a of the support member 741 is pushed up. As a result, the holding surface 71a of the table 70 has a medium-convex shape.

In this way, in the holding unit 7, since the central portion 750, the first ring portion 751 and the second ring portion 752 can be individually raised and lowered to change the shape of the holding surface 71a, the holding unit 7 is held on the holding surface 71a. The shape of the surface Wa of the workpiece W to be processed and processed can be adjusted.

In particular, in a state where the holding surface deforming means 75 and the table 70 are tilted in the + X direction using the tilt changing shaft 791 as shown in FIG. 6, for example, the contact surface 755a of the first piezoelectric actuator 755A is centered 750. Consider the case where the central portion 750 is pushed up by abutting the lower surface 750b of the above.
The force of the first piezoelectric actuator 755A pushing up the central portion 750 is applied in an upward direction parallel to the axis 765 inclined in the + X direction from the Z axis. On the other hand, since the weight of the central portion 750 is applied in the −Z direction, the central portion 750 is not only in the upward direction parallel to the shaft 765 but also in the direction parallel to the holding surface 71a (in FIG. 6). A force is also applied (the direction between the + X direction and the -Z direction). Therefore, if the holding surface deforming means 75 is not provided with the guide portion 756 provided with the groove 756a and the sphere 756b, the central portion 750 moves in the direction between the + X direction and the −Z direction. As a result, the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751 come into contact with each other. When the central portion 750 rises, if the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751 are in contact with each other, the central portion 750 receives resistance due to the frictional force acting between both surfaces. Therefore, the smooth rise is hindered. Further, when the position of the central portion 750 is deviated in the direction parallel to the holding surface 71a, the contact surface 755a of the first piezoelectric actuator 755A can be brought into contact with an appropriate position on the lower surface 755b of the central portion 750. Therefore, the central portion 750 cannot be raised in the direction perpendicular to the holding surface 71a.
In that respect, in the present invention, when the first piezoelectric actuator 755A pushes up the central portion 750 in the direction parallel to the shaft 765, the groove 756a and the sphere 756b housed in the groove 756a act to act on the central portion 750. Movement in the direction between the + X direction and the -Z direction is restricted. That is, the side surface 750c of the central portion 750 and the inner side surface 751d of the first ring portion 751 are prevented from coming closer than a certain distance by being blocked by the ball 756b that is in sliding contact with the side surface 756c of the groove 756a. As a result, it is possible to prevent the side surface 750c of the central portion 750 from coming into contact with the inner side surface 751d of the first ring portion 751, and the central portion 750 can be raised perpendicularly to the holding surface 71a. Further, the three balls 756b rotate while sliding in contact with the groove 756a, so that the central portion 750 is smoothly raised. The same applies to the relationship between the first ring portion 751 and the second ring portion 752, and prevents the side surface 751c of the first ring portion 751 from coming into contact with the inner side surface 752d of the second ring portion 752. Then, the first ring portion 751 can be raised perpendicularly to the holding surface 71a.

The second piezoelectric actuator 755B and the third piezoelectric actuator 755C are operated in the same manner as when the central portion 750 is raised by using the first piezoelectric actuator 755A, and the first ring portion 751 and the second ring are operated. The portion 752 can be raised in a direction perpendicular to the holding surface 71a.
At that time, a plurality of grooves 756a and spheres 756b arranged between the first ring portion 751 and the second ring portion 752 and between the second ring portion 752 and the tubular portion 753 are formed. By acting in the same manner, the first ring portion 751 and the second ring portion 752 are prevented from being displaced in the direction between the + X direction and the −Z direction, and the outer side surface 751c of the first ring portion 751 is formed. It is possible to prevent the inner side surface 752d of the second ring portion 752 from coming into contact with the outer side surface 752c of the second ring portion 752 and the inner side surface 753d of the tubular portion 753.

The above-mentioned effects of the grooves 756a and the sphere 756b are exhibited not only when the central portion 750, the first ring portion 751 and the second ring portion 752 are raised, but also when they are lowered. Needless to say, from this, the central portion 750, the first ring portion 751, and the second ring portion 752 are moved up and down in the direction perpendicular to the holding surface 71a of the table 70, respectively, and centered on the shaft 765. The holding surface 71a can be deformed while maintaining the same height on the same circumference.

As described above, after the holding surface 71a of the table 70 is deformed into a desired shape by using the holding surface deforming means 75, the Z-axis direction moving means 5 is controlled again to drive the polishing means 4 to rotate. The polishing pad 44 is lowered to a height position where it comes into contact with the surface Wa of the workpiece W. Then, the polishing pad 44 is brought into contact with the surface Wa of the workpiece W to restart the polishing process. At this time, similarly, the thickness of the workpiece W is measured by using a non-contact thickness measuring device or the like using measurement light during the polishing process, and when the thickness becomes uneven again, the polishing process is interrupted. The holding surface 71a is deformed by using the holding surface deforming means 75. The workpiece W can be finished to a uniform thickness by appropriately abutting the polishing pad 44 and deforming the holding surface 71a.

In addition, for example, in CMP polishing or dry polishing in which the polishing pad 44 is brought into contact with the surface Wa of the workpiece W held on the table 70 to polish the workpiece W, the workpiece W is used. The area near the center is easily polished. In such a case, for example, after polishing to some extent, the height of the contact surface 755a is adjusted so that the height position of the central portion 750 is lower than the height position of the first ring portion 751 and the height position is lower than that of the first ring portion 751. By positioning the height position of the ring portion 751 of 1 lower than the height position of the second ring portion 752, the holding surface 71a of the table 70 is deformed into a hollow shape, and then polishing is performed again. The surface Wa of the workpiece W can be flattened.

By using the holding surface deforming means 75, the shape of the holding surface 71a can be transformed into various shapes not limited to the above-mentioned mid-convex and mid-concave. For example, by raising the height of the central portion 750, the height of the first ring portion 751, and the height of the second ring portion 752 by the same amount, the holding surface 71a of the table 70 is kept flat while the table is kept flat. The height of 70 can also be increased.

According to the present invention, in order to make the thickness of the workpiece W uniform, the height of the contact surface 775a of the piezoelectric actuator 755 is adjusted instead of cutting the polishing member 441 of the polishing pad 44 to adjust the polished surface. By pushing up the table 70, the shape of the holding surface 71a is reversibly deformed, so that the consumption of the polishing member 441 can be suppressed and the long-term processing quality can be maintained.
Further, the holding surface may be controlled to be parallel to or slightly tilted with respect to the grinding surface of the grinding wheel by using the grinding device for grinding the workpiece with the grinding wheel.

1: Processing equipment 2: Control means 3: Slurry supply means 30: Slurry flow path 30a: Inlet 30b: Outlet 4: Polishing means 40: Spindle 41: Spindle housing 42: Motor 43: Mount 44: Polishing pad 440: Disc 441 : Polishing member 45: Rotating shaft 5: Z-axis direction moving means 50: Ball screw 51: Guide rail 52: Motor 53: Lifting plate 54: Holder 55: Rotating shaft 7: Holding unit 70: Table 71: Suction part 71a: Holding surface 72: Frame 73: Suction source 74: Communication means 741: Support member 75: Holding surface deformation means 750: Central part 750a: Central part upper surface 750b: Central part lower surface 750c: Central part side surface 751: First ring Part 751a: Upper surface of the first ring portion 751b: Lower surface of the first ring portion 751c: Outer side surface of the first ring 751d: Inner side surface of the first ring 752: Second ring portion 752a: Second 752b: Lower surface of the second ring portion 752c: Outer side surface of the second ring portion 752d: Inner side surface of the second ring portion 753: Cylindrical portion 753d: Inner side surface of the tubular portion 754: Base 754a: Top surface of base 755A, 755B, 755C: piezoelectric actuator 755a: Contact surface 756: Guide part 756a: Groove 756b: Sphere 756c: Groove side surface 76: Rotating means 760: Rotary joint 761: Motor 762: Casing 765 : Rotating shaft 77: Cover 78: Bellows 790: Strut 791: Tilt changing shaft 8: Y-axis direction moving means 80: Ball screw 81: Guide rail 82: Motor 83: Y-axis base 85: Rotating shaft 90: Power supply unit W: Cover Workpiece Wa: Upper surface of the work piece D1: Distance between the central part and the first ring part D2: Distance between the first ring part and the second ring part D3: Between the second ring part and the cylinder part interval

Claims (3)

A holding unit having a holding surface for holding a work piece.
A table having the holding surface on the upper surface, and a communicating means for communicating the holding surface with the suction source.
A holding surface deforming means for supporting the table from below and deforming the holding surface is provided.
The holding surface deforming means includes a columnar central portion whose center is positioned on an axis passing through the center of the holding surface.
A first ring portion surrounding the central portion and
A second ring portion surrounding the first ring portion and
A tubular portion that surrounds the second ring portion and
A base that closes the lower end of the cylinder and
Between the upper surface of the base and the lower surface of the central portion, between the upper surface of the base and the lower surface of the first ring portion, and between the upper surface of the base and the lower surface of the second ring portion. Piezoelectric actuators arranged in between,
A holding unit including a guide portion that allows each of the central portion, the first ring portion, and the second ring portion to be raised and lowered in a direction perpendicular to the holding surface. The guide part
It is arranged at at least three places at an equal angle around the center of the holding surface.
A groove formed so as to face the respective side surfaces of the central portion and the first ring portion, the first ring portion and the second ring portion, and the second ring portion and the tubular portion. ,
The holding unit according to claim 1, further comprising a ball or roller housed in the groove and movable in the vertical direction. A processing apparatus including the holding unit according to claim 1.
A power supply unit that supplies a DC voltage to the piezoelectric actuator,
A control means for controlling the voltage supplied to each of the piezoelectric actuator that supports the central portion, the piezoelectric actuator that supports the first ring portion, and the piezoelectric actuator that supports the second ring portion. Prepare,
The voltage is controlled by the control means, the length of the piezoelectric actuator is changed, the heights of the central portion, the first ring portion, and the second ring portion are adjusted, and the shape of the holding surface is deformed. A processing device that processes an workpiece held by the holding surface with a processing tool of a processing means.

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