JP7835545B2 - polishing equipment - Google Patents

Description

This invention relates to a polishing apparatus for polishing workpieces.

In the semiconductor manufacturing field, CMP (Computer-Mounted Polishing) equipment is known for polishing and planarizing silicon wafers and the like (hereinafter referred to as "workpieces").

The polishing apparatus described in Patent Document 1 is a polishing apparatus that applies chemical mechanical polishing, or CMP (Chemical Mechanical Polishing) technology. This CMP apparatus polishes the workpiece by pressing it against a polishing pad while it is mounted on a polishing head.

Japanese Patent Publication No. 2016-159385

Incidentally, in back-reference polishing, where the back surface of the workpiece is held in the chuck of the polishing head and the front surface of the workpiece is pressed against the polishing pad for polishing, the pressure distribution acting on the workpiece is set to be approximately uniform in the circumferential direction. Therefore, due to the crystal orientation of the workpiece, the shape of the polished workpiece may be tilted, or workpieces with uneven initial film thickness in the circumferential direction may not be able to be polished to a uniform thickness.

Therefore, technical challenges arise that need to be addressed in order to polish workpieces with high precision, and the present invention aims to solve these challenges.

To achieve the above objective, the polishing apparatus according to the present invention is a polishing apparatus that polishes a workpiece held in a polishing head by pressing it against a polishing pad on a platen, comprising: a chuck capable of holding the workpiece on a holding surface which serves as a polishing surface ; a plurality of partial pressing parts arranged in parallel along the circumferential direction of the chuck, which are expanded by air and act on the entire surface of the workpiece via the chuck, forming a non-uniform pressure distribution within the polishing surface in the circumferential direction of the workpiece, thereby pressing the workpiece toward the polishing pad with a non-uniform pressure distribution in the circumferential direction of the workpiece; and a controller capable of adjusting the pressure of the air supplied to each partial pressing part.

This configuration allows for precise and flat polishing of the workpiece by expanding and contracting multiple partial pressure zones, thereby freely adjusting the pressure distribution acting on the workpiece in the circumferential direction. This allows for corresponding pressure distributions in the circumferential direction of the workpiece, taking into account the crystal orientation and uneven initial film thickness. This enables the application of different polishing pressures within the polishing surface, resulting in highly accurate and flat polishing.

This invention enables the precise and flat grinding of a workpiece.

A schematic perspective view showing a CMP apparatus according to one embodiment of the present invention. A schematic longitudinal cross-sectional view showing the main parts of the polishing head. A plan view showing the relative positions of the first airbag and the second airbag. A plan view showing the positional relationship between the workpiece and the second airbag. (a) is a schematic diagram showing the pressure distribution by the first airbag, and (b) is a schematic diagram showing the pressure distribution by the first airbag and the second airbag. This image shows the pressure exerted on the workpiece W when each of the four second airbags was inflated and deflated. A schematic diagram illustrating the process of calculating the air pressure supplied to the second airbag when a desired pressure is applied at an arbitrary peak position. (a) is a graph showing the amount of material removed by polishing on the X axis in Examples 1 and 2 and Comparative Example 1, and (b) is a graph showing the amount of material removed by polishing on the Y axis in Examples 1 and 2 and Comparative Example 1. (a) is a graph showing the amount of material removed by polishing on the X axis in Examples 3 and 4 and Comparative Example 2, and (b) is a graph showing the amount of material removed by polishing on the Y axis in Examples 3 and 4 and Comparative Example 2. (a) is a graph showing the thickness of the workpiece on the X-axis in Example 5, and (b) is a graph showing the thickness of the workpiece on the Y-axis in Example 5. (a) is a graph showing the amount of material removed by polishing on the X axis in Example 5, and (b) is a graph showing the amount of material removed by polishing on the Y axis in Example 5. This graph shows the range of variation in workpiece thickness during each step of Example 5.

One embodiment of the present invention will be described based on the drawings. In the following, when referring to the number, numerical values, quantities, ranges, etc., of components, unless specifically stated or clearly limited to a particular number in principle, the number is not limited to that particular number; it may be greater than or less than that number.

Furthermore, when referring to the shape, positional relationship, etc. of constituent elements, unless otherwise explicitly stated or clearly considered otherwise in principle, this includes elements that substantially approximate or resemble those shapes, etc.

Furthermore, drawings may exaggerate features by enlarging characteristic parts to make them easier to understand, and the dimensional ratios of components may not necessarily be the same as in reality. Also, in cross-sectional views, hatching may be omitted for some components to make the cross-sectional structure easier to understand.

Figure 1 is a schematic perspective view of a CMP apparatus 1 according to one embodiment of the present invention. The CMP apparatus 1 polishes one surface of a workpiece W to a flat surface. The CMP apparatus 1 comprises a platen 2 and a polishing head 10. The workpiece W is, for example, a silicon wafer, but is not limited to this.

The platen 2 is formed in a disc shape and is connected to a rotating shaft 3 located below it. The rotating shaft 3 rotates due to the drive of the motor 4, causing the platen 2 to rotate in the direction of arrow D1 in Figure 1. A polishing pad 5 is attached to the upper surface of the platen 2, and a CMP slurry, a mixture of abrasive and chemicals, is supplied onto the polishing pad 5 from a nozzle (not shown).

The polishing head 10 is formed to have a smaller diameter than the platen 2 and is connected to a rotating shaft 10a located above the polishing head 10. The rotating shaft 10a rotates due to the drive of a motor (not shown), causing the polishing head 10 to rotate in the direction of arrow D2 in Figure 1. The polishing head 10 is configured to be movable in the vertical and horizontal directions by a head movement mechanism (not shown). When polishing the workpiece W, the polishing head 10 descends and presses the workpiece W against the polishing pad 5.

The operation of the CMP device 1 is controlled by the controller 6. The controller 6 controls each of the components that make up the CMP device 1. The controller 6 is, for example, a computer, and is composed of a CPU, memory, etc. The functions of the controller 6 may be implemented by software control or by hardware operation.

Next, the structure of the polishing head 10 will be described. Figure 2 is a schematic longitudinal cross-sectional view showing the main parts of the polishing head 10.

The polishing head 10 comprises a head body 11 connected to a rotating shaft 10a. The head body 11 is connected to a base member 13 via a rotation transmission unit 12, and the head body 11, rotation transmission unit 12, and base member 13 rotate together with the rotating shaft 10a.

A plate holder 14 made of PPS is fastened to the upper part of the base member 13 via bolt B1. This transmits the rotational driving force input to the polishing head 10 to the plate holder 14 via the base member 13.

A first airbag 15 and a second airbag 16 are interposed between the plate holder 14 and the head body 11.

The first airbag 15 is formed in a substantially annular shape. The first airbag 15 can be inflated and deflated by air supplied from a compressed air source (not shown) via a compressed air line 15a. The pressure of the air supplied from the compressed air source is regulated by a regulator (not shown) controlled by a controller 6. The first airbag 15 pressurizes the entire plate holder 14 according to the supplied air pressure, thereby adjusting the polishing pressure at which the entire workpiece W is pressed against the polishing pad 5.

There are four second airbags 16. Furthermore, the second airbags 16 are housed within the first airbags 15. As shown in Figure 3, the four second airbags 16 are each formed in a substantially circular shape and, when viewed from above, are arranged in substantially concentric circles around the rotation center of the polishing head 10.

As shown in Figure 4, the four second airbags 16 are positioned one in the positive and negative regions on each of the mutually orthogonal X-axis or Y-axis passing through the center of the workpiece W. Hereafter, when distinguishing between the four second airbags 16, the second airbag 16 positioned in the negative region on the Y-axis near the orientation flat OF will have "a" appended to its designation, and the second airbags 16 will be labeled "B," "C," and "D" in clockwise order when viewed from a plane, with second airbag 16A as the reference. Note that the number of second airbags 16 is not limited to four; it may be three or less, or five or more.

The second airbag 16 is capable of being inflated and deflated by air supplied from a compressed air source (not shown) via a compressed air line 16a. The pressure of the air supplied from the compressed air source is adjusted by a regulator (not shown) controlled by a controller 6. The second airbag 16, in response to the supplied air pressure, pressurizes a portion of the plate holder 14 located directly below it, thereby locally changing the polishing pressure applied to the workpiece W by the polishing pad 5 in the circumferential direction of the workpiece W. Furthermore, because the second airbag 16 is fixed to the lower surface of the highly rigid head body 11 and configured to be inflatable downwards, the inflation and deflation of the second airbag 16 can be easily controlled compared to, for example, a case where the second airbag 16 is stacked on the lower surface of an inflatable first airbag 15.

Returning to Figure 2, a porous chuck 17 is provided below the base member 13. The porous chuck 17 comprises an alumina chuck table 18 and a porous alumina chuck 19.

The chuck table 18 is fastened to the base member 13 via bolts B2. This allows the rotational driving force input to the polishing head 10 to be transmitted to the porous chuck 17 via the base member 13.

The chuck 19 is embedded in the underside of the chuck table 18. The chuck 19 is connected via line 18a to a vacuum source and a cooling water source (not shown). By activating the vacuum source, the workpiece W is held by suction on the holding surface 17a of the porous chuck 17. The cooling water supplied from the cooling water source is temperature-controlled to approximately room temperature, and the chuck 19 is cooled by passing the water through it after polishing.

In this manner, the polishing head 10 holds the back surface of the workpiece W by suction to the chuck 19, and the front surface of the workpiece W is pressed against the polishing pad 5. As the first airbag 15 and the second airbag 16 inflate, a load is transmitted to the workpiece W, causing it to be polished so that the shape of the holding surface 17a, which serves as the polishing surface, is transferred to the workpiece W (back surface reference polishing). The holding surface 17a is set to a flatness of approximately 1 μm or less by lapping.

Next, the procedure for adjusting the load applied to the workpiece W by the first airbag 15 or the second airbag 16 will be described.

First, as shown in Figure 5(a), with the load from the first airbag 15 (hereinafter referred to as "normal load"), a convex pressure distribution is obtained where the pressure is high near the center of the workpiece W, and gradually decreases from the center towards the outer circumference. Since this pressure distribution under normal load is formed almost uniformly in the circumferential direction of the workpiece W, it is not suitable for polishing a workpiece W that has tilted after polishing due to crystal orientation or has an uneven initial film thickness to a nearly uniform thickness.

By adjusting the air pressure supplied to the second airbags 16A to 16D, the pressure distribution acting on the workpiece W can be changed. Figures 6(a) to (i) are images showing the pressure acting on the workpiece W when the first airbag 15 is deflated and the second airbags 16A to 16D are inflated and deflated, using the Nitta Corporation's surface pressure distribution measurement system "I-SCAN". Brighter areas indicate stronger pressure. Note that the images in Figures 6(a) to (i) show the pressure distribution acting on the workpiece W as viewed from the bottom, and the positive and negative directions of the X-axis are reversed compared to Figure 4.

Figure 6(a) shows the pressure acting on the workpiece W when air at a pressure of 8.5 psi is supplied to the second airbags 16C and 16D, respectively. Figure 6(b) shows the pressure acting on the workpiece W when air at a pressure of 12 psi is supplied to the second airbag 16C. Figure 6(c) shows the pressure acting on the workpiece W when air at a pressure of 8.5 psi is supplied to the second airbags 16B and 16C, respectively. Figure 6(d) shows the pressure acting on the workpiece W when air at a pressure of 12 psi is supplied to the second airbag 16D. Figure 6(e) shows the pressure acting on the workpiece W when air at a pressure of 12 psi is supplied to any of the second airbags 16A to 16D. Figure 6(f) shows the pressure acting on the workpiece W when no air is supplied. Figure 6(g) shows the pressure acting on the workpiece W when 12 psi of air is supplied to the second airbag 16B. Figure 6(h) shows the pressure acting on the workpiece W when 8.5 psi of air is supplied to the second airbags 16A and 16D, respectively. Figure 6(i) shows the pressure acting on the workpiece W when 12 psi of air is supplied to the second airbag 16A and 16B, respectively.

As shown in Figures 6(b), (d), (f), and (h), when any one of the second airbags 16A to 16D is pressurized, the pressure acting directly below and around the pressurized second airbag 16A to 16D increases.

Furthermore, as shown in Figures 6(a), (c), (g), and (i), when two adjacent second airbags 16A to 16D are pressurized, the pressure acting directly below and around the two pressurized second airbags 16A to 16D, as well as the pressure between them, increases.

In this way, when shifting the pressure distribution in the circumferential direction of the workpiece W, as shown in Figure 7, the pressure F to be applied to the peak position P, where the pressure distribution in the circumferential direction of the workpiece W is maximum, is vector-decomposed according to the coordinates of the peak position P, and the air pressure to be supplied to the two adjacent second airbags 16A to 16D on either side of the peak position P is calculated.

That is, as shown in Figure 7, when setting the peak position P between the second airbags 16C and 16D, if Θ is the angle between the line segment connecting the peak position P and the origin O and the X-axis, then the pressure applied to the second airbag 16C is set to FsinΘ, and the pressure applied to the second airbag 16D is set to FcosΘ. For example, if the angle Θ is set to 60 degrees and the pressure applied to the peak position P is set to 12 psi, then the air pressure supplied to the second airbag 16C is set to 10.4 psi, and the air pressure supplied to the second airbag 16D is set to 6 psi.

In this way, as shown in Figure 5(b), the pressure distribution obtained under the load from the second airbag 16 (hereinafter referred to as "partial load") has a different shape than that obtained under normal load. That is, the pressure distribution under partial load is formed non-uniformly in the circumferential direction of the workpiece W. Therefore, by combining normal load and partial load, an appropriate pressure distribution can be set according to the crystal orientation and initial film thickness of the workpiece W, and a workpiece W with a substantially uniform film thickness after polishing can be obtained.

Furthermore, since the second airbag 16 is housed within the first airbag 15, when the second airbag 16 is inflated while the first airbag 15 is inflated, the air pressure supplied to the second airbag 16 is set to be higher than the air pressure supplied to the first airbag 15.

Specifically, if we denote the pressure of the air supplied to the first airbag 15 as Pall, the area of the workpiece W as Sw, the area of the first airbag 15 as Sa, and the pressure at which the porous chuck 17 pressurizes the workpiece W as WP, then the air pressure Pz supplied to the second airbag 16 is set such that Pz > Pall = (Sw/Sa) * WP.

Furthermore, the combination of normal load and partial load can be simultaneous or sequential. For example, the workpiece W may have a singularity around the orientation flat OF, where a phenomenon of discontinuous increase in material removal (dullness) may occur during grinding and polishing. Therefore, after normal polishing by inflating only the first airbag 15 and polishing the workpiece W, the first airbag 15 is deflated, and then the second airbags 16B to 16D are inflated sequentially to polish the workpiece W excluding the area around the orientation flat OF. By polishing the entire surface of the workpiece W excluding the area around the orientation flat OF, the dullness around the orientation flat OF can be eliminated.

Next, we will describe the case where CMP polishing was performed on a workpiece W made of LiTaO3 (lithium tantalate) under a normal load (Comparative Example 1), and the case where CMP polishing was performed using a combination of normal and partial loads (Examples 1 and 2).

Table 1 shows the polishing conditions for Comparative Example 1 and Examples 1 and 2. Figure 8(a) shows the distribution of polishing removal amount on the X-axis (Y-coordinate: 0) for Comparative Example 1 and Examples 1 and 2, and Figure 8(b) shows the distribution of polishing removal amount on the Y-axis (X-coordinate: 0). In Table 1, "Zone 3" and "Zone 4" correspond to the second airbags 16C and 16D, respectively.

As shown in Figures 8(a) and 8(b), in Comparative Example 1, the amount of material removed by polishing in the negative X-coordinate region (especially below -25 mm) is relatively larger than the amount removed by polishing in the positive X-coordinate region, and the amount removed by polishing in the negative Y-coordinate region (especially below -25 mm) is relatively larger than the amount removed by polishing in the positive Y-coordinate region. Therefore, it can be seen that there is a bias in the amount of material removed by polishing within the W-plane of the workpiece.

On the other hand, in Example 1, by applying partial loads from the second airbags 16C and 16D in addition to the normal load from the first airbag 15, the amount of material removed by polishing in the positive X-coordinate region and the amount of material removed in the positive Y-coordinate region increased, and it can be seen that the unevenness of the amount of material removed by polishing within the workpiece W surface was mitigated.

Furthermore, in Example 2, by further increasing the pressure of the air supplied to the second airbags 16C and 16D, the amount of material removed in the positive X-coordinate region and the positive Y-coordinate region are further increased. Since the amount of material removed in the positive X-coordinate region is relatively larger than that in the negative X-coordinate region, and the amount of material removed in the positive Y-coordinate region is relatively larger than that in the negative Y-coordinate region, it can be seen that the bias in the amount of material removed within the workpiece W surface is in contrast to that of Comparative Example 1.

Next, we will describe the case where CMP polishing is performed on a workpiece W made of SiC (silicon carbide) under a normal load (Comparative Example 2), and the case where CMP polishing is performed using a combination of normal and partial loads (Examples 3 and 4).

Table 2 shows the polishing conditions for Comparative Example 2 and Examples 3 and 4. Figure 9(a) shows the distribution of polishing removal amount on the X-axis (Y-coordinate: 0) for Comparative Example 2 and Examples 3 and 4, and Figure 9(b) shows the distribution of polishing removal amount on the Y-axis (X-coordinate: 0). Note that "Zone 4" in Table 1 corresponds to the second airbag 16D.

As shown in Figures 9(a) and 9(b), in Comparative Example 2, the amount of material removed by polishing in the negative X-coordinate region tends to be relatively larger than the amount removed by polishing in the positive X-coordinate region, indicating a bias in the amount of material removed by polishing within the W-plane of the workpiece.

On the other hand, in Example 3, by applying a partial load from the second airbag 16D in addition to the normal load from the first airbag 15, it can be seen that the amount of material removed by polishing in the region where the X coordinate is positive increases, and the unevenness of the amount of material removed by polishing within the workpiece W surface is mitigated.

Furthermore, in Example 4, by further increasing the pressure of the air supplied to the second airbag 16D, the amount of polishing removed in the positive X-coordinate region increased further. The amount of polishing removed in the positive X-coordinate region tended to be relatively larger than the amount removed in the negative X-coordinate region, indicating a bias in the amount of polishing removed within the workpiece W surface that is in contrast to Comparative Example 2.

Next, we will describe the case in which the workpiece W, made of LiTaO3, is partially pressurized in stages to improve the sagging around the orientation flat OF (Example 5). The polishing conditions in Example 5 are shown in Table 3. In Table 3, "Zone 1" corresponds to the first airbag 16A, "Zone 2" corresponds to the first airbag 16B, "Zone 3" corresponds to the first airbag 16C, and "Zone 4" corresponds to the first airbag 16D.

Figure 10(a) shows the thickness of the workpiece W on the X-axis (Y-coordinate: 0) in each process, and Figure 10(b) shows the thickness of the workpiece W on the Y-axis (X-coordinate: 0) in each process. Furthermore, Figure 11(a) shows the distribution of polishing removal amount on the X-axis (Y-coordinate: 0) in each process, and Figure 11(b) shows the distribution of polishing removal amount on the Y-axis (X-coordinate: 0) in each process. Figure 12 is a graph showing the variation in thickness within the surface of the workpiece W in each process.

In Figures 10(a), (b), and 12, "Before Polishing" indicates the workpiece W before CMP polishing under normal load. As shown in Figure 10(b), significant sagging occurs around the orientation flat OF (Y-coordinate: -50 mm or less), resulting in a substantial reduction in the thickness of the workpiece W. Furthermore, as shown in Figure 12, a thickness variation of approximately 0.34 μm is observed within the surface of the workpiece W.

For such a workpiece W, first, only the first airbag 15 is inflated to polish the workpiece W (normal polishing). As shown in Figures 10(a) and (b), the workpiece W after normal polishing is polished to a concave shape, with the thinnest point near the center and gradually increasing in thickness towards the outer edge. Also, as shown in Figures 11(a) and (b), the amount of material removed during normal polishing is greatest near the center and gradually decreases towards the outer edge. However, as shown in Figure 12, there is no significant change in the thickness variation within the surface of the workpiece W before and after normal polishing.

Next, after deflating the first airbag 15, the second airbags 16B to 16D are inflated sequentially to partially polish the entire surface of the workpiece W, excluding the area around the orientation flat OF (partial polishing 1). In partial polishing 1, as shown in Figures 11(a) and (b), it can be seen that, on the Y-axis, the area around the orientation flat OF is hardly polished, and the amount of material removed is significantly greater in the region from the middle to the periphery of the workpiece W (X <- approximately 25 mm and approximately 25 mm < X, approximately 25 mm < Y) compared to the area near the center of the workpiece W. As a result, after partial polishing 1, as shown in Figures 10(a) and (b), the entire surface of the workpiece W, excluding the area around the orientation flat OF, is polished, and the concave shape of the workpiece W is alleviated. Furthermore, as shown in Figure 12, it can be seen that the thickness variation within the surface of the workpiece W has been improved to 0.25 μm.

In this embodiment, after partial pressurization 1, a second stage of partial pressurization (partial polishing 2) is performed by sequentially inflating the second airbags 16A to 16D to further polish the workpiece W. Partial polishing 2 improves the concave shape created during normal polishing, forming a nearly flat workpiece W. It may be omitted if the amount of material removed during normal polishing is small and the concave shape of the workpiece W after normal polishing is shallow.

In partial polishing 2, as shown in Figures 11(a) and (b), the amount of material removed during polishing is significantly greater in the region from the middle to the periphery of the workpiece W (X <- approximately 25 mm and approximately 25 mm < X, Y <- approximately 25 mm and approximately 25 mm < Y) compared to the central part of the workpiece W. As a result, the concave shape of the workpiece W after partial polishing 2 is further reduced, as shown in Figures 10(a) and (b). Furthermore, as shown in Figure 12, the thickness variation within the surface of the workpiece W is further improved to 0.2 μm.

Thus, the CMP apparatus 1 according to this embodiment is a polishing apparatus that polishes a workpiece W held by a polishing head 10 by pressing it against a polishing pad 5 on a platen 2. It comprises a chuck 19 capable of holding the workpiece W, second airbags 16A to 16D arranged in parallel along the circumferential direction of the chuck 19 and capable of inflating with air to press a portion of the workpiece W toward the polishing pad 5, and a controller 6 capable of adjusting the air pressure supplied to the second airbags 16A to 16D.

With this configuration, the pressure distribution acting on the workpiece W can be freely adjusted in the circumferential direction of the workpiece W by inflating and deflating the second airbags 16A to 16D. Therefore, the pressure distribution can be adjusted to accommodate the crystal orientation and non-uniform initial film thickness of the workpiece W, and by applying different polishing pressures to the workpiece W within the polishing surface, the workpiece W can be polished accurately and flatly.

Furthermore, the CMP apparatus 1 according to this embodiment further includes a first airbag 15 provided around the entire circumference of the chuck 19, which inflates with air to press the entire surface of the workpiece W toward the polishing pad 5. The second airbags 16A to 16D are housed within the first airbag 15.

With this configuration, the second airbags 16A to 16D are positioned so as to overlap the first airbag 15 when viewed from above. This allows for easy adjustment of the pressure distribution acting on the workpiece W by combining the uniform pressure distribution provided by the first airbag 15 with the non-uniform pressure distribution provided by the second airbags 16A to 16D.

Furthermore, the present invention can be modified in various ways beyond those described above, as long as it does not deviate from the spirit of the invention, and it goes without saying that the present invention extends to such modified versions.

In the above-described embodiment, a CMP device 1 was explained as an example, comprising a first airbag 15 that pressurizes the workpiece W with a substantially uniform pressure distribution in the circumferential direction, and second airbags 16A to 16D that pressurize the workpiece W with a non-uniform pressure distribution in the circumferential direction. However, for example, instead of the second airbags 16A to 16D, the first airbag 15 may be divided into multiple air chambers, and when pressurizing the workpiece W with a substantially uniform pressure distribution in the circumferential direction, all air chambers may be inflated, and when pressurizing the workpiece W with a non-uniform pressure distribution in the circumferential direction, at least one air chamber may be inflated.

1: CMP device 2: Platen 3: Rotating shaft (of the platen) 4: Motor 5: Polishing pad 6: Controller 10: Polishing head 10a: Rotating shaft (of the polishing head) 11: Head body 12: Rotation transmission unit 13: Base member 14: Plate holder 15: First airbag (overall pressing unit)
16, 16A-16D: Second airbag (partial pressure section)
17: Porous chuck 17a: Holding surface 18: Chuck table 19: Chuck W: Workpiece

Claims (1)

A polishing device that polishes a workpiece held in a polishing head by pressing it against a polishing pad on a platen,
A chuck capable of holding the workpiece on the holding surface which serves as the polishing surface,
Multiple partial pressing sections are arranged in parallel along the circumferential direction of the chuck, and are expanded by air to form a non-uniform pressure distribution within the polishing surface that acts on the entire surface of the workpiece via the chuck, thereby pressing the workpiece toward the polishing pad with a non-uniform pressure distribution in the circumferential direction of the workpiece.
A controller that allows for adjustment of the air pressure supplied to each individual pressing section,
A total pressing section is provided around the entire circumference of the chuck, which expands with air and acts on the entire surface of the workpiece via the chuck, forming a uniform pressure distribution within the polishing surface in the circumferential direction of the workpiece, and pressing the entire surface of the workpiece toward the polishing pad with a uniform pressure distribution in the circumferential direction of the workpiece.
Equipped with ,
The polishing apparatus is characterized in that the partial pressing portion is housed within the overall pressing portion .