JP2021045821A - Abrasive pad and grinding method - Google Patents

Abstract

To provide an abrasive pad and a grinding method that are able to appropriately reduce variations in grinding rate.SOLUTION: An abrasive pad 1 grinds a workpiece fixed to a leading end of a spindle and held on a hold table. During grinding, the abrasive pad 1 is brought into contact with the workpiece held on the hold table, thereby the hold table and the abrasive pad 1 are arranged in a positional relation in which pressures applied to the workpiece differ within a plane of the workpiece. The abrasive pad 1 is formed over an outer edge 9 from a center 1-1 of a contact surface 5 of the abrasive pad 1 with the workpiece and has, between the center 1-1 and the outer edge 9, a maximum part 3-1 in which a circumferential width 4 of the contact surface 5 becomes maximum. A notch 2 is formed in the abrasive pad such that a circumferential width 4 becomes gradually wider toward the maximum part 3-1 from the center 1-1 and the circumferential width 4 becomes gradually narrower toward the outer edge 9 from the maximum part 3-1.SELECTED DRAWING: Figure 5

Description

The present invention relates to a polishing pad and a polishing method.

There is known a grinding and polishing apparatus that uses a conical holding table whose shape can be easily controlled during grinding for both grinding and polishing (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-150642

Since the polishing pad covers the entire surface of the work piece, when polishing using a conical holding table, the work piece is most easily polished at the apex of the cone of the holding table, and the work piece is covered toward the outer circumference of the holding table. There is a problem that the polishing rate varies because the work piece is difficult to polish.

The present invention has been made in view of such problems, and an object of the present invention is to provide a polishing pad and a polishing method capable of appropriately reducing variations in polishing rate.

In order to solve the above-mentioned problems and achieve the object, the polishing pad of the present invention is a polishing pad fixed to the tip of a spindle and polished on a workpiece held on a holding table, and the polishing pad and the holding table are used. With the polishing pad, the polishing pad comes into contact with the workpiece held on the holding table during polishing, so that the pressure applied to the workpiece is arranged in a different positional relationship in the plane of the workpiece. The polishing pad is formed from the center of the contact surface of the polishing pad with the work piece to the outer edge, and the maximum portion between the center and the outer edge where the width of the contact surface in the circumferential direction is maximized. A notch is formed in which the width in the circumferential direction gradually widens from the center toward the maximum portion, and the width in the circumferential direction gradually narrows from the maximum portion toward the outer edge. It is characterized by.

Further, in order to solve the above-mentioned problems and achieve the object, the polishing method of the present invention is a polishing method for polishing a workpiece held on a holding table by a polishing pad fixed to the tip of a spindle. When the holding table and the polishing pad come into contact with the work piece held on the holding table during polishing, the pressure applied to the work piece is applied in the plane of the work piece. Arranged in different positional relationships, the polishing method includes a pressure calculation step for calculating the variation of the pressure applied in the plane of the workpiece during the polishing step based on the shape of the holding table, and the pressure calculation step. Based on the measured pressure, the width of the contact surface of the polishing pad with the work piece is maximized in the region where the pressure applied to the work piece is maximum in the surface of the work piece, and the width is the width. A notch forming step of forming a notch that decreases from the region toward the center or the outer edge on the contact surface, a holding step of holding the work piece on the holding table, and a work piece held on the holding table. It is characterized by comprising a polishing step in which a polishing pad on which the notch is formed is brought into contact with an object, and the object to be polished is polished while rotating at least one of the holding table and the polishing pad.

In the polishing pad and the polishing method, the holding table has a conical shape, and the pressure applied to the workpiece may increase as it is closer to the center of the holding table.

According to the present invention, the variation in polishing rate can be appropriately reduced.

FIG. 1 is a perspective view showing a configuration example of a grinding and polishing apparatus which is an example of an apparatus using the polishing pad according to the first embodiment. FIG. 2 is a cross-sectional view showing a main part of the grinding and polishing apparatus of FIG. FIG. 3 is a top view showing a main part of the polishing unit of the grinding and polishing apparatus of FIG. FIG. 4 is a sectional view taken along line IV-IV of FIG. FIG. 5 is a plan view showing the polishing pad according to the first embodiment. FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 7 is a flowchart showing the flow of the polishing method according to the first embodiment. FIG. 8 is a graph showing an example of the pressure distribution obtained in the pressure calculation step of the polishing method of FIG. 7. FIG. 9 is a plan view showing the polishing pad according to the second embodiment. FIG. 10 is a cross-sectional view showing a pressure calculation step in the polishing method according to the third embodiment. FIG. 11 is a graph showing the variation in the polishing amount of the workpiece according to the embodiment. FIG. 12 is a graph showing the variation in the polishing amount of the workpiece according to the comparative example.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
The polishing pad 1 and the polishing method according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration example of a grinding and polishing apparatus 100, which is an example of an apparatus using the polishing pad 1 according to the first embodiment. FIG. 2 is a cross-sectional view showing a main part of the grinding / polishing apparatus 100 of FIG. FIG. 3 is a top view showing a main part of the polishing unit 40 of the grinding and polishing apparatus 100 of FIG. FIG. 4 is a sectional view taken along line IV-IV of FIG.

As shown in FIG. 1, the grinding and polishing apparatus 100 is installed on the apparatus main body 10, the first grinding unit 20, the second grinding unit 30, the polishing unit 40, the turntable 50, and the turntable 50. For example, four holding tables 60, a pressure measuring unit 70 provided in the vicinity of the polishing unit 40, a control unit 80, cassettes 91 and 92, an alignment unit 93, a loading unit 94, and a loading unit 95. A cleaning unit 96 and a loading / unloading unit 97 are mainly provided.

In the present embodiment, the workpiece 200 to be processed by the grinding apparatus 100 is, for example, a disk-shaped semiconductor wafer or an optical device wafer whose base material is silicon, sapphire, gallium arsenide, or the like. The workpiece 200 may have a device formed on the surface 201, or may be an asslice wafer before device formation.

The turntable 50 is a disk-shaped table provided on the upper surface of the apparatus main body 10, is rotatably provided in a horizontal plane, and is rotationally driven at a predetermined timing. On the turntable 50, for example, four holding tables 60 are arranged at equal intervals with a phase angle of, for example, 90 °. These four holding tables 60 are sequentially moved to the carry-in / carry-out position 301, the rough grinding position 302, the finish grinding position 303, the polishing position 304, and the carry-in / carry-out position 301 by the rotation of the turntable 50.

These four holding tables 60 are rotatably provided on the turntable 50 independently of the turntable 50. These four holding tables 60 suck and hold the surface 201 side of the workpiece 200 with the holding surface 61. In the present embodiment, these four holding tables 60 are formed in a conical shape having a center 60-1, which is the center of rotation of the holding table 60, as an apex and a slightly lower outer circumference, as shown in FIGS. 2 and 3. There is. Therefore, the workpiece 200 is suction-held by the holding surface 61 of the holding table 60 whose front surface 201 side is formed in a conical shape, so that the front surface 201 side is concave and the back surface 202 side is convex. It becomes a state. Further, as shown in FIG. 2, these four holding tables 60 include a rotating shaft adjusting unit 62 that inclines the rotating shaft of the holding table 60 with respect to the Z-axis direction parallel to the vertical direction.

As shown in FIG. 1, the first grinding unit 20 is a workpiece held on a holding table 60 at a rough grinding position 302 while rotating a grinding wheel 23 having a grinding wheel 22 mounted on the lower end of a spindle 21. The back surface 202 of the workpiece 200 is roughly ground by pressing the back surface 202 of the work piece 200 along the Z-axis direction parallel to the vertical direction by the Z-axis feed unit 24. In the present embodiment, specifically, as shown in FIG. 2, the first grinding unit 20 tilts the rotating shaft of the holding table 60 by a predetermined angle with respect to the Z-axis direction by the rotating shaft adjusting unit 62. Then, the back surface 202 of the workpiece 200 is roughly ground in a state where the ground surface of the grinding wheel 23 and the holding surface 61 of the holding table 60 are in contact with each other.

The second grinding unit 30 is placed on the holding table 60 located at the finishing grinding position 303 while rotating the grinding wheel 33 having the grinding wheel 32 mounted on the lower end of the spindle 31 in the same manner as the first grinding unit 20. The back surface 202 of the workpiece 200 that has been roughly ground is pressed against the back surface 202 of the workpiece 200 by the Z-axis feed unit 34 along the Z-axis direction to finish grind the back surface 202 of the workpiece 200. In the second grinding unit 30, the rotating shaft of the holding table 60 is tilted by the rotating shaft adjusting unit 62, and the grinding surface by the grinding wheel 33 and the holding surface of the holding table 60 are substantially similar to the first grinding unit 20. The back surface 202 of the workpiece 200 is finish-ground in a state where the 61 is in contact with each other.

In the present embodiment, the first grinding unit 20 and the second grinding unit 30 grind the back surface 202 side of the workpiece 200 while supplying a grinding liquid such as pure water to the back surface 202 side of the workpiece 200. To do.

As shown in FIG. 2, the polishing unit 40 arranges the polishing pad 1 according to the present embodiment of the polishing tool 42 mounted on the lower end of the spindle 41 so as to face the holding surface 61 of the holding table 60. The polishing unit 40 rotates the polishing tool 42 and puts the polishing pad 1 of the polishing tool 42 on the back surface 204 of the work piece 200 that has been finish-ground and is held by the holding surface 61 of the holding table 60 located at the polishing position 304. This is for polishing the back surface 204 of the workpiece 200 by pressing the side with the Z-axis feed unit 44 along the Z-axis direction.

In the polishing unit 40, the holding table 60 and the polishing pad 1 come into contact with the back surface 202 of the workpiece 200 held by the holding table 60 with the contact surface 5 which is the polishing surface of the polishing pad 1 during polishing. The back surface 204 of the workpiece 200 is polished while the pressure applied to the workpiece 200 is arranged in different positional relationships in the plane of the workpiece 200. In the present embodiment, specifically, as shown in FIG. 3, the polishing unit 40 has a rotation shaft of the polishing tool 42 and the polishing pad 1 and a rotation shaft of the holding surface 61 of the holding table 60 for holding the workpiece 200. By setting the above in a state of being spaced apart in the Y-axis direction, which is the horizontal direction, a state in which the pressure applied to the workpiece 200 is different in the plane of the workpiece 200 is realized.

As shown in FIGS. 3 and 4, the polishing pad 1 has a larger diameter in the horizontal direction than the holding table 60. As shown in FIGS. 3 and 4, a part 9-1 of the outer edge 9 of the contact surface 5 of the polishing pad 1 overlaps a part 69-1 of the outer edge 69 of the holding table 60 in the Z-axis direction. The other part 69-2 of the outer edge 69 on the opposite side of the part 69-1 of the outer edge 69 sandwiching the center 60-1 of the holding table 60 is the contact surface 5 of the polishing pad 1 as shown in FIG. It is arranged at a position on the side of the outer edge 69 away from a part 69-1 of the center 1-1. As shown in FIGS. 3 and 4, the radial direction connecting a part 69-1 of the outer edge 69 of the holding table 60 and the other part 69-2 overlaps with the radial direction of the polishing pad 1. More specifically, as shown in FIG. 3, the outer edge 9 of the contact surface 5 of the polishing pad 1 is circumscribed with respect to the outer edge 69 of the holding table 60.

In the present embodiment, the polishing unit 40 uses the polishing pad 1 to polish the back surface 202 of the workpiece 200 while supplying a slurry containing abrasive grains as a polishing liquid, but the present invention is not limited to this, and polishing is performed. The back surface 202 of the workpiece 200 may be polished using a polishing pad 1 having fixed abrasive grains while supplying pure water as a liquid, and the polishing pad 1 may be used while supplying an alkaline polishing liquid as a polishing liquid. Chemical mechanical polishing (CMP) may be performed, or dry polishing may be performed on the back surface 202 of the workpiece 200 using the polishing pad 1 without supplying the polishing liquid.

FIG. 5 is a plan view showing the polishing pad 1 according to the first embodiment. FIG. 6 is a sectional view taken along line VI-VI of FIG. As shown in FIG. 5, the polishing pad 1 has a notch 2 formed from the center 1-1 of the contact surface 5 of the polishing pad 1 with the workpiece 200 to the outer edge 9. The notch 2 has a maximum portion 3-1 having a maximum width 4 in the circumferential direction of the contact surface 5 between the center 1-1 and the outer edge 9, and is directed from the center 1-1 toward the maximum portion 3-1. Therefore, the width 4 in the circumferential direction gradually widens, and the width 4 in the circumferential direction gradually narrows from the maximum portion 3-1 toward the outer edge 9.

In the first embodiment, the notch 2 formed on the contact surface 5 of the polishing pad 1 specifically has a maximum portion 3-1 having a maximum width 4 in the vicinity of a distance 3 from the center 1-1. ing. Here, the maximum portion 3-1 refers to a region at a distance of 3 with respect to the center 1-1 and a region in the vicinity thereof. The maximum portion 3-1 corresponds to a region where the pressure applied to the workpiece 200 is maximum in the plane of the workpiece 200 due to the conical apex at the center 60-1 of the holding table 60. There is. Further, in the notch 2 formed on the contact surface 5 of the polishing pad 1, in the first embodiment, the width 4 of the contact surface 5 in the circumferential direction is 0 at the center 1-1 and the outer edge 9. When the apex of the conical shape that is the center of the holding table 60 is located at the position of 1/3 of the diameter of the polishing pad 1, the circumference on 1/3 of the diameter of the polishing pad 1 is the maximum portion 3-1. Is preferable.

In the first embodiment, the notch 2 is divided into four parts having the same shape and area, and is arranged on the contact surface 5 of the polishing pad 1 with the workpiece 200. The notch 2 is not limited to this in the present invention, and may be one or more. Considering the man-hours required for manufacturing, the notch 2 is preferably divided into 8 or less and arranged, and in this case, the notch 2 can be suitably formed on the contact surface 5 of the polishing pad 1. Further, in order to equalize the influence of heat generated on the contact surface 5 of the polishing pad 1 during processing, it is preferable that the divided portions of the notch 2 are arranged at equal intervals. The invention is not limited to this, and may be arranged at non-uniform intervals.

In the first embodiment, the depth 6 of the notch 2 formed in the polishing pad 1 is equal to the thickness 7 of the polishing pad 1 as shown in FIG. That is, the notch 2 formed in the polishing pad 1 is formed as a through hole in the polishing pad 1. The depth 6 of the notch 2 formed in the polishing pad 1 is not limited to this in the present invention, and may be formed on the contact surface 5 as a non-penetrating recess shallower than the thickness 7 of the polishing pad 1. .. The notch 2 can be formed on the contact surface 5 of the polishing pad 1 by using, for example, a cutting device or a grinding device (not shown).

As shown in FIG. 1, the cassettes 91 and 92 are containers for accommodating a plurality of workpieces 200. Further, the alignment unit 93 is a table for temporarily placing the workpiece 200 taken out from the cassette 91 and aligning the center thereof.

The carry-in unit 94 has a suction pad, and sucks and holds the workpiece 200 before grinding and polishing aligned by the alignment unit 93 and carries it onto the holding table 60 located at the carry-in / carry-out position 301. The carry-out unit 95 sucks and holds the work piece 200 after grinding and polishing held on the holding table 60 located at the carry-in / carry-out position 301, and carries it out to the cleaning unit 96. The cleaning unit 96 cleans the workpiece 200 after grinding and polishing, and removes contamination such as grinding debris and polishing debris adhering to the ground and polished processed surface.

The loading / unloading unit 97 is, for example, a robot pick provided with a circular hand 97-1, and the workpiece 200 is sucked and held by the circular hand 97-1 to convey the workpiece 200. Specifically, the carry-in / out unit 97 carries out the work piece 200 before grinding and polishing from the cassette 91 to the alignment unit 93, and carries in the work piece 200 after grinding and polishing from the cleaning unit 96 to the cassette 92. ..

The control unit 80 controls each of the above-mentioned components constituting the grinding and polishing apparatus 100. That is, the control unit 80 causes the grinding and polishing apparatus 100 to perform a grinding and polishing operation on the workpiece 200. The control unit 80 is a computer capable of executing a computer program. The control unit 80 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. And have. The arithmetic processing unit of the control unit 80 executes a computer program stored in the storage device to generate a control signal for controlling the grinding / polishing device 100. The arithmetic processing unit of the control unit 80 outputs the generated control signal to each component of the grinding / polishing device 100 via the input / output interface device.

FIG. 7 is a flowchart showing the flow of the polishing method according to the first embodiment. As shown in FIG. 7, the polishing method according to the first embodiment includes a pressure calculation step ST1, a notch forming step ST2, a holding step ST3, and a polishing step ST4.

The pressure calculation step ST1 is a step of calculating the variation in the pressure applied in the plane of the workpiece 200 during the polishing step ST4, which will be described later, based on the shape of the holding table 60.

In the pressure calculation step ST1, the control unit 80 polishes with the holding table 60, which determines the amount of inclination of the conical shape of the holding table 60 and the position of the apex of the cone of the holding table 60 on the contact surface 5 of the polishing pad 1. The pressure distribution P of the contact surface 5 is calculated based on the positional relationship with the pad 1.

FIG. 8 is a graph showing an example of the pressure distribution P obtained in the pressure calculation step ST1 of the polishing method of FIG. 7. In the pressure calculation step ST1, in the present embodiment, the control unit 80 is formed with the holding table 60 holding the workpiece 200 having its rotation center as the apex and the outer circumference being formed in a slightly low conical shape. For example, as shown in FIG. 8, the pressure applied along the Z-axis direction according to the distance from the center 200-1 (center 60-1 of the holding table 60) which is the center of rotation of the workpiece 200. Obtains a pressure distribution P in which is substantially linearly and monotonically decreasing. In the pressure distribution P shown in FIG. 8, in the present embodiment, for example, it is 30 kPa near the center 200-1 of the workpiece 200 and 21 kPa near the outer circumference of the workpiece 200 (near the outer edge 69 of the holding table 60). It has become.

The notch forming step ST2 is performed after the pressure calculation step ST1. In the notch forming step ST2, based on the pressure distribution P calculated in the pressure calculation step ST1, the contact surface 5 of the polishing pad 1 is located in the region where the pressure applied to the workpiece 200 is maximum in the plane of the workpiece 200. A maximum portion 3-1 having a maximum width 4 in the circumferential direction is provided, and a notch 2 whose width 4 decreases toward the center 1-1 or the outer edge 9 from the maximum portion 3-1 is processed by the polishing pad 1. This is a step of forming on the contact surface 5 with the object 200.

In the notch forming step ST2, specifically, based on the pressure distribution P calculated in the pressure calculation step ST1, the pressure applied to the work piece 200 corresponds to the region where the pressure applied to the work piece 200 is maximum in the plane of the work piece 200. The maximum portion 3-1 is provided. In the notch forming step ST2, the shape of the notch 2 is determined by determining the position where the maximum portion 3-1 is provided and the notch width 4 at a plurality of radial positions of the polishing pad 1 from the calculated pressure distribution P. It is determined appropriately, but at this time, the width 4 in the circumferential direction decreases from the maximum portion 3-1 toward the center 1-1, and the width 4 in the circumferential direction decreases from the maximum portion 3-1 toward the outer edge 9. The shape of the notch 2 is determined so as to decrease. In the notch forming step ST2, after the shape of the notch 2 is determined, the notch 2 having the determined shape is formed on the contact surface 5 of the polishing pad 1 by using a cutting device or a grinding device (not shown).

By forming the notch 2 on the contact surface 5 of the polishing pad 1 in the notch forming step ST2, the pressure applied to the workpiece 200 and the contact time of the polishing pad 1 during polishing (polishing step ST4 described later) The product is equalized over the entire surface of the workpiece 200. In the example of the first embodiment, for example, since the width 4 of the notch 2 is large in the vicinity of the center 200-1 of the workpiece 200, the contact time of the polishing pad 1 is about 0.7 times, and the outer circumference of the workpiece 200 is increased. Since the width 4 of the notch 2 is small and almost nonexistent in the vicinity (near the outer edge 69 of the holding table 60), the contact time of the polishing pad 1 is maintained at about 1.0 times. Therefore, the product of the pressure applied to the workpiece 200 and the contact time of the polishing pad 1 during polishing is 30 kPa × (contact time before forming the notch 2) × in the vicinity of the center 200-1 of the workpiece 200. It becomes about 0.7 times, and in the vicinity of the outer circumference of the workpiece 200 (near the outer edge 69 of the holding table 60), it becomes 21 kPa × (contact time before forming the notch 2) × about 1.0 times, which are almost equal to each other. Therefore, it can be seen that it is homogenized.

The holding step ST3 is a step of holding the workpiece 200 on the holding table 60. Before the holding step ST3, the pressure sheet moving unit 72 retracts the pressure sheet 71 placed at the pressure measurement position in the pressure calculation step ST1 to the retracted position. Further, before the polishing step ST4 described later, the polishing pad 1 having the notch 2 formed in the notch forming step ST2 is attached to the polishing tool 42, and the polishing tool 42 to which the polishing pad 1 is attached is attached to the lower end of the spindle 41. Attach to.

The polishing step ST4 is performed after the holding step ST3, and the polishing pad 1 having the notch 2 formed is brought into contact with the workpiece 200 held by the holding table 60, and at least one of the holding table 60 and the polishing pad 1 is rotated. This is a step of polishing the workpiece 200 while allowing the work piece 200 to be polished. In the polishing step ST4, it is preferable to polish according to the polishing setting when forming the notch 2 in the polishing pad 1 in the notch forming step ST2. In the present embodiment, the polishing pad 1 side is processed by the spindle 41. The object 200 is polished by the polishing pad 1 while rotating the object 200 side by a rotation mechanism provided on the holding table 60.

The polishing method according to the first embodiment has a width in a region where the pressure applied to the workpiece 200 is maximum in the plane of the workpiece 200 based on the pressure calculated in the pressure calculation step ST1 in the notch forming step ST2. A maximum portion 3-1 having a maximum value of 4 is provided, and a notch 2 whose width 4 decreases as it goes from the maximum portion 3-1 toward the center 1-1 or the outer edge 9 is formed in the workpiece 200 of the polishing pad 1. It is formed on the contact surface 5 with. Further, since the polishing pad 1 according to the embodiment has the above-described configuration, a maximum portion 3-1 having a maximum width 4 in the circumferential direction of the contact surface 5 is provided between the center 1-1 and the outer edge 9. In preparation, the width 4 in the circumferential direction gradually widens from the center 1-1 toward the maximum portion 3-1 and the width 4 in the circumferential direction gradually narrows toward the outer edge 9 from the maximum portion 3-1. The notch 2 is formed on the contact surface 5 of the polishing pad 1 with the workpiece 200. Therefore, in the polishing method and the polishing pad 1 according to the embodiment, the pressure applied to the workpiece 200 and the polishing pad during polishing due to the notch 2 formed on the contact surface 5 of the polishing pad 1 with the workpiece 200. Since the product with the contact time of 1 is equalized over the entire surface of the work piece 200, the pressure applied to the work piece 200 is arranged in a different positional relationship in the plane of the work piece 200. Even if it is present, it has the effect of appropriately reducing the variation in the polishing rate.

Further, in the present embodiment, when the holding table 60 and the polishing pad 1 come into contact with the workpiece 200 held by the holding table 60 during polishing, the pressure applied to the workpiece 200 is applied. In the form in which the holding table 60 is arranged in different positional relationships in the plane of the work piece 200, the pressure applied to the work piece 200 becomes larger as it is closer to the center 60-1 of the holding table 60. There is. The polishing method and the polishing pad 1 according to the embodiment have an effect that even when the holding table 60 has a conical shape, the variation in the polishing rate can be appropriately reduced.

[Embodiment 2]
The polishing pad 1-2 according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a plan view showing the polishing pad 1-2 according to the second embodiment. In FIG. 9, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 9, the polishing pad 1-2 according to the second embodiment has the notch 2-2 instead of the notch 2 in the polishing pad 1 according to the first embodiment, and the contact surface with the workpiece 200. It is formed in 5. Like the notch 2, the notch 2-2 has a maximum portion 3-1 between the center 1-1 and the outer edge 9 that maximizes the width 4 of the contact surface 5 in the circumferential direction, and the center 1-1. The width 4 in the circumferential direction gradually widens toward the maximum portion 3-1 and the width 4 in the circumferential direction gradually narrows toward the outer edge 9 from the maximum portion 3-1. The notch 2 according to the first embodiment is divided into four parts and arranged at equal intervals with a phase angle of 90 °, while the notch 2-2 is divided into two parts and has a phase angle of 180 °. It differs from the notch 2 according to the first embodiment in that it is arranged at equal intervals.

As described above, the polishing pad 1-2 according to the second embodiment is the polishing pad 1 according to the first embodiment in which the number of divided portions of the notch 2-2 is changed, and the other configurations are the same. is there. Therefore, the polishing pads 1-2 according to the second embodiment have the same effects as those of the first embodiment.

[Embodiment 3]
The polishing method according to the third embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a cross-sectional view showing the pressure calculation step ST1 in the polishing method according to the third embodiment. In FIG. 10, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The polishing method according to the third embodiment is a modification of the pressure calculation step ST1 in the polishing method according to the first embodiment. In the pressure calculation step ST1 according to the third embodiment, as shown in FIG. 10, the pressure measuring unit 70 is used, and the work piece 200 is subjected to the polishing step ST4 described later based on the shape of the holding table 60. This is a step of calculating the variation of the applied pressure in the plane.

As shown in FIG. 10, the pressure measuring unit 70 includes a pressure sheet 71 and a pressure sheet moving unit 72. The pressure sheet 71 is a pressure measuring member that measures the applied pressure, is formed in a plate shape, and can be wound up in a roll shape. The pressure sheet moving unit 72 moves the pressure sheet 71 between the pressure measuring position between the polishing pad 1 and the workpiece 200 and the retracting position where the pressure sheet 71 is retracted from the pressure measuring position. The pressure sheet moving unit 72 is placed at the pressure measurement position with the pressure sheet 71 spread out in a plate shape, and is retracted to the retracted position with the pressure sheet 71 wound up in a roll shape.

In the pressure calculation step ST1 according to the third embodiment, as shown in FIG. 10, the pressure sheet moving unit 72 first places the pressure sheet 71 at the pressure measurement position between the polishing pad 1 and the workpiece 200. To do. In the pressure calculation step ST1 according to the third embodiment, next, the Z-axis feed unit 44 does not rotate the polishing pad 1 according to the present embodiment in the polishing tool 42 mounted on the lower end of the spindle 41 in the Z-axis direction. Presses against the back surface 204 of the workpiece 200 via the pressure sheet 71. In the pressure calculation step ST1 according to the third embodiment, the pressure sheet 71 presses the polishing pad 1 against the workpiece 200 via the pressure sheet 71, and Z is between the polishing pad 1 and the workpiece 200. The pressure applied along the axial direction is measured, and the pressure measurement result is transmitted to the control unit 80. In the pressure calculation step ST1 according to the third embodiment, the same pressure distribution P as the pressure calculation step ST1 according to the first embodiment is obtained.

As described above, the polishing method according to the third embodiment is a modification of the pressure calculation step ST1 in the polishing method according to the first embodiment, and the other configurations are the same. Therefore, the polishing method according to the third embodiment has the same effect as that of the first embodiment.

〔Example〕
Next, the inventors of the present invention confirmed the effects of the polishing pad 1 and the polishing method according to the first embodiment. In the confirmation, in each of the example using the polishing pad 1 having the notch 2 formed and the comparative example using the conventional polishing pad not forming the notch 2, the work piece 200 was subjected to the polishing unit 40. The back surface 202 of the above was polished. FIG. 11 is a graph showing the variation in the polishing amount of the workpiece 200 according to the embodiment. FIG. 12 is a graph showing the variation in the polishing amount of the workpiece 200 according to the comparative example. In FIGS. 11 and 12, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the example using the polishing pad 1 having the notch 2 formed, as shown in FIG. 11, the polishing amount which is the difference between the maximum value and the minimum value of the polishing amount on the polished surface of the work piece 200 after polishing. The variation was a polishing amount difference of 300. On the other hand, in the comparative example using the conventional polishing pad, as shown in FIG. 12, the polishing amount is generally maximum at the center 200-1 and the polishing amount is generally minimum at the outer periphery on the polished surface of the work piece 200 after polishing. Therefore, the variation in the polishing amount on the polished surface of the workpiece 200 was a polishing amount difference of 400, which was larger than the polishing amount difference of 300 in the example shown in FIG.

Each result of the example and the comparative example is applied to the workpiece 200 by forming the holding table 60 into a conical shape due to the effect of the notch 2 which is a conditional difference provided between the two. Despite the non-uniform pressure, the product of the pressure applied to the work piece 200 during polishing and the time it takes for the polishing pad 1 to come into contact is equalized over the entire surface of the work piece 200. It was found that the variation in the amount of polishing was reduced on the entire surface of the workpiece 200. That is, it was found that the notch 2 can appropriately reduce the variation in the polishing rate.

The present invention is not limited to the above embodiment. That is, it can be modified in various ways without departing from the gist of the present invention. In the first and second embodiments, the maximum portion 3-1 is located on the center 60-1 of the holding table 60, and the width 4 of the notch 2 in the circumferential direction is 0 at the center 1-1 and the outer edge 9. However, in the present invention, the maximum portion 3-1 may be separated from the center 60-1 of the holding table 60, and the width 4 in the circumferential direction of the notch 2 is the center 1-1 and the outer edge 9. It does not have to be 0. In short, in the present invention, the notch 2 includes a maximum portion 3-1 having a maximum width 4 in the circumferential direction of the contact surface 5 between the center 1-1 and the outer edge 9, and the maximum portion from the center 1-1. It is sufficient that the width 4 in the circumferential direction gradually widens toward 3-1 and the width 4 in the circumferential direction gradually narrows toward the outer edge 9 from the maximum portion 3-1.

Further, the polishing method according to the first and second embodiments implements the pressure calculation step ST1, but the polishing method of the present invention is not limited to this, and the notch is not performed without performing the pressure calculation step ST1. In the forming step ST2, the maximum portion 3-1 having the maximum width 4 in the circumferential direction of the contact surface 5 is provided between the center 1-1 and the outer edge 9, and the direction from the center 1-1 to the maximum portion 3-1 is provided. Therefore, the notch 2 may be formed in which the width 4 in the circumferential direction gradually widens and the width 4 in the circumferential direction gradually narrows from the maximum portion 3-1 toward the outer edge 9.

1,1-2 Polishing pad 1-1,60-1,200-1 Center 2,2-2 Notch 3 Distance 3-1 Maximum part 4 Width 5 Contact surface 6 Depth 7 Thickness 9,69 Outer edge 40 Polishing unit 41 Spindle 42 Polishing tool 60 Holding table 61 Holding surface 80 Control unit 100 Grinding and polishing equipment 200 Work piece

Claims (4)

A polishing pad that is fixed to the tip of the spindle and holds on the holding table to polish the workpiece.
The holding table and the polishing pad are located at different positions in the plane of the work piece due to the contact of the polishing pad with the work piece held on the holding table during polishing. Placed in a relationship,
The polishing pad is formed from the center of the contact surface of the polishing pad with the workpiece to the outer edge, and the maximum portion between the center and the outer edge where the width of the contact surface in the circumferential direction is maximized. A notch is formed in which the width in the circumferential direction gradually increases from the center toward the maximum portion, and the width in the circumferential direction gradually narrows from the maximum portion toward the outer edge. A featured polishing pad. A polishing method in which a work piece held on a holding table is polished by a polishing pad fixed to the tip of a spindle.
The holding table and the polishing pad are located at different positions in the plane of the work piece due to the contact of the polishing pad with the work piece held on the holding table during polishing. Placed in a relationship,
The polishing method is
A pressure calculation step for calculating the variation in pressure applied in the plane of the workpiece during the polishing step based on the shape of the holding table, and a pressure calculation step.
Based on the pressure measured in the pressure calculation step, the width of the contact surface of the polishing pad with the workpiece is maximized in the region where the pressure applied to the workpiece is maximum in the plane of the workpiece. A notch forming step that forms a notch in the contact surface, the width of which decreases from the region towards the center or outer edge.
A holding step of holding the work piece on the holding table,
A polishing step in which a polishing pad on which the notch is formed is brought into contact with a work piece held on the holding table, and the work piece is polished while rotating at least one of the holding table and the polishing pad.
A polishing method characterized by comprising. The polishing pad according to claim 1, wherein the holding table has a conical shape, and the pressure applied to the workpiece increases as it approaches the center of the holding table. The polishing method according to claim 2, wherein the holding table has a conical shape, and the pressure applied to the workpiece increases as it approaches the center of the holding table.

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