JP7566423B2 - Polishing Pad - Google Patents

Description

The present invention relates to a polishing pad for polishing a workpiece.

In the device chip manufacturing process, a wafer is used in which devices are formed in multiple areas partitioned by multiple planned division lines (streets) arranged in a grid pattern. By dividing this wafer along the planned division lines, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

In recent years, as electronic devices have become smaller and thinner, there is a demand for device chips to be thinner as well. Therefore, a process of thinning the wafer by grinding is sometimes carried out before dividing the wafer. For the grinding process, a grinding device is used that includes a chuck table that holds the workpiece and a grinding unit to which a grinding wheel including a grinding stone is attached (see Patent Document 1). With the wafer held by the chuck table, the chuck table and the grinding wheel are each rotated while the grinding stone is brought into contact with the wafer, thereby grinding and thinning the wafer.

After grinding, scratches (grinding marks, saw marks) formed by contact with the grinding wheel remain on the wafer. If the wafer with the grinding marks is divided to produce device chips, the grinding marks remain on the device chips, reducing their flexural strength (bending strength). Therefore, the grinding marks cause a decrease in the quality of the device chips.

Therefore, after the grinding process, the ground surface (ground surface) of the wafer is polished. The polishing process is performed by rotating a disk-shaped polishing pad and pressing it against the ground surface of the wafer (see Patent Document 2). The polishing process removes the grinding marks remaining on the ground surface of the wafer, and suppresses the decrease in the flexural strength of the device chips obtained by dividing the wafer.

JP 2000-288881 A Japanese Patent Application Publication No. 8-99265

A polishing pad used for polishing workpieces such as wafers has an abrasive layer that comes into contact with the workpiece to polish it. The material and hardness of the abrasive layer are appropriately selected according to the material of the workpiece to be polished. When the abrasive layer of the polishing pad is rotated and brought into contact with the grinding surface of the workpiece, the grinding surface of the workpiece is polished and any grinding marks remaining on the grinding surface are removed.

Here, it has been confirmed that the hardness of the polishing layer of the polishing pad affects the processing conditions and processing results in the polishing process. Specifically, if the hardness of the polishing layer is high, the polishing time required to remove grinding marks is shortened, but the surface roughness of the workpiece after polishing increases, and the quality of the workpiece decreases. On the other hand, if the hardness of the polishing layer is low, the surface roughness of the workpiece after polishing is reduced, but the polishing time required to remove grinding marks is long. Therefore, if one of shortening the polishing time and improving the quality of the workpiece is prioritized, the other is sacrificed.

In addition, by setting the hardness of the polishing layer to a medium level, it may be possible to keep both the polishing time and the surface roughness of the workpiece below a certain level. However, even if a polishing layer with a medium hardness is used, it is not possible to shorten the polishing time to the same extent as when a polishing layer with a high hardness is used, and it is also not possible to reduce the surface roughness of the workpiece to the same extent as when a polishing layer with a low hardness is used. In other words, in polishing, it is difficult to achieve both a shortened polishing time and an improvement in the quality of the workpiece.

The present invention was made in consideration of these problems, and aims to provide a polishing pad that can shorten the polishing time while obtaining high-quality workpieces.

According to one aspect of the present invention, there is provided a polishing pad for polishing a workpiece, comprising a disk-shaped polishing layer containing a resin having air holes, the polishing layer comprising a first polishing layer including a first polishing surface that contacts the workpiece, and a second polishing layer including a second polishing surface that contacts the workpiece , the hardness of the first polishing layer being 41 or more and 70 or less as measured by Durometer Type D, and the hardness of the second polishing layer being 25 or more and 40 or less as measured by Durometer Type D.

Preferably, the first polishing layer and the second polishing layer are alternately provided along the circumferential direction of the polishing layer. Also, preferably, the first polishing layer and the second polishing layer are formed in a fan shape extending from the center of the polishing layer to the outer periphery. Also, preferably, the polishing layer includes a plurality of the first polishing layers and a plurality of the second polishing layers.

Also, preferably, the polishing layer comprises a plurality of the first polishing layers and a plurality of the second polishing layers, and the first polishing layers and the second polishing layers are arranged alternately along two directions perpendicular to each other. Also, preferably, the polishing layer comprises a plurality of the first polishing layers and a plurality of the second polishing layers, and the first polishing layers and the second polishing layers are in a strip shape and arranged alternately. Also, preferably, the resin is polyurethane, and the porosity of the first polishing layer and the second polishing layer is different.

The polishing pad according to one aspect of the present invention has a polishing layer containing a resin having air holes, and the polishing layer has a first polishing layer and a second polishing layer having different hardnesses. By polishing a workpiece with the polishing pad, it is possible to obtain a high-quality workpiece while shortening the polishing time.

FIG. FIG. 2 is a plan view showing the polishing layer. FIG. 3A is a plan view showing an abrasive layer divided into eight parts, and FIG. 3B is a plan view showing an abrasive layer divided into 16 parts. Figure 4(A) is a plan view showing an abrasive layer having rectangular first and second abrasive layers, and Figure 4(B) is a plan view showing an abrasive layer having strip-shaped first and second abrasive layers.

An embodiment according to one aspect of the present invention will be described below with reference to the attached drawings. First, an example of the configuration of a polishing device capable of polishing a workpiece using a polishing pad according to this embodiment will be described. FIG. 1 is a perspective view showing a polishing device 2. In FIG. 1, the X-axis direction (first horizontal direction) and the Y-axis direction (second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

The polishing device 2 includes a support unit 4 that supports the polishing pad 12 and a holding unit 20 that holds the workpiece 11. The workpiece 11 held by the holding unit 20 is pressed against the polishing pad 12, whereby the workpiece 11 is polished.

The support unit 4 includes a disk-shaped support base (platen) 6 made of metal, ceramics, resin, etc. The upper surface of the support base 6 is a flat surface that is roughly parallel to the horizontal direction (XY plane direction) and forms a circular support surface 6a that supports the polishing pad 12.

The center of the underside of the support base 6 is fixed to the upper end of a cylindrical spindle 8 arranged along the Z-axis direction. A rotational drive source 10 such as a motor that rotates the spindle 8 is connected to the lower end of the spindle 8. The support base 6 rotates around a rotation axis roughly parallel to the Z-axis direction by the power transmitted from the rotational drive source 10 via the spindle 8.

A polishing pad 12 for polishing the workpiece 11 is fixed on the support table 6. The polishing pad 12 has a disk-shaped polishing layer 14, which is attached to the support surface 6a of the support table 6 by an adhesive or the like. The upper surface of the polishing layer 14 corresponds to the polishing surface for polishing the workpiece 11, and is disposed approximately parallel to the horizontal direction (XY plane direction).

The polishing layer 14 is composed of abrasive grains (fixed abrasive grains) and a binder that holds the abrasive grains. The materials of the abrasive grains and the binder can be freely set according to the material of the workpiece 11. For example, it is preferable to use abrasive grains made of silica (SiO ₂ ) and a binder that contains a resin having pores as a main component. There is no limit to the size of the abrasive grains, and abrasive grains with an average particle size of 100 nm or more and 10 μm or less can be used. In addition, a foamed resin (foamed plastic) such as polyurethane can be used as the resin having pores.

The abrasive layer 14 includes at least one each of a first abrasive layer 16 and a second abrasive layer 18, which have different hardnesses. Details of the first abrasive layer 16 and the second abrasive layer 18 will be described later (see Figures 2 to 4(B)).

A holding unit 20 is provided above the support unit 4. The holding unit 20 has a disk-shaped holding portion 22 that holds the workpiece 11. The holding portion 22 is positioned so as to overlap the area between the center and the outer periphery of the polishing layer 14.

A holding member (not shown) that holds the workpiece 11 is provided on the underside of the holding section 22. For example, the holding member includes a circular substrate having a diameter larger than that of the workpiece 11, and a holding film (backing film) provided on the surface (underside) side of the substrate. For example, the substrate is made of a resin such as polyethylene terephthalate (PET), and the holding film is made of suede-like urethane foam or the like. The holding member is positioned so that the holding film is exposed on the underside of the holding section 22.

When the workpiece 11 is wetted with water or the like and brought into contact with the holding film, the workpiece 11 is adsorbed to the holding film by surface tension and is held by the holding part 22. However, there are no limitations on the method for holding the workpiece 11 by the holding part 22.

The center of the upper surface of the holding part 22 is fixed to the lower end of a cylindrical spindle 24 arranged along the Z-axis direction. A drive mechanism 26 that drives the spindle 24 is connected to the upper end of the spindle 24. The drive mechanism 26 includes a rotational drive source such as a motor that rotates the spindle 24, and a lifting mechanism such as an air cylinder that moves (raises and lowers) the spindle 24 along the Z-axis direction.

The holding part 22 rotates about a rotation axis that is roughly parallel to the Z-axis direction by power transmitted from the rotation drive source of the drive mechanism 26 via the spindle 24. In addition, by raising and lowering the spindle 24 by the lifting mechanism of the drive mechanism 26, the holding part 22 moves along the Z-axis direction and moves closer to and away from the polishing pad 12 relatively.

In addition, in an area above the support unit 4 where the holding unit 20 is not provided, a supply unit 28 is provided to supply polishing liquid to the polishing pad 12. The supply unit 28 includes a nozzle 30 connected to a polishing liquid supply source (not shown), and the nozzle 30 supplies polishing liquid 32 toward the upper surface (polishing surface) of the polishing pad 12 at a predetermined flow rate.

There are no limitations on the material of the polishing liquid 32. For example, an alkaline solution in which sodium hydroxide, potassium hydroxide, or the like is dissolved, or an acidic solution in which an organic acid, or the like is dissolved, can be used as the polishing liquid 32. Pure water can also be used as the polishing liquid 32.

The polishing layer 14 does not have to contain abrasive grains (fixed abrasive grains). In this case, a chemical solution (slurry) in which abrasive grains (loose abrasive grains) are dispersed is used as the polishing liquid supplied from the supply unit 28. As the loose abrasive grains, for example, colloidal silica with an average grain size of about 80 nm is used. However, the material of the chemical solution, the material of the abrasive grains, the grain size of the abrasive grains, etc. are appropriately selected depending on the material of the workpiece 11, etc.

When polishing the workpiece 11 with the polishing device 2, the workpiece 11 is first held by the holding unit 20. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has a front surface and a back surface that are generally parallel to each other.

The workpiece 11 is partitioned into a number of rectangular regions by a number of planned division lines (streets) that are arranged in a grid pattern so as to intersect with one another. In addition, a number of devices are formed on the front surface side of the workpiece 11 in the regions partitioned by the planned division lines. Examples of devices include ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems). When the workpiece 11 is partitioned along the planned division lines, a number of device chips each equipped with a device are obtained.

There are no limitations on the type, material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of devices formed on the workpiece 11, and no devices may be formed on the workpiece 11.

Then, while the polishing pad 12 is rotated by the rotary drive source 10 at a predetermined number of rotations in a predetermined direction (the direction indicated by arrow A), the holding part 22 holding the workpiece 11 is rotated by the drive mechanism 26 at a predetermined number of rotations in a predetermined direction (the direction indicated by arrow B), and the holding part 22 is lowered by the drive mechanism 26. As a result, the workpiece 11 comes into contact with the upper surface (polishing surface) of the polishing layer 14 of the polishing pad 12 and is polished. Polishing of the workpiece 11 continues until the workpiece 11 reaches a predetermined thickness.

For example, when manufacturing device chips from the workpiece 11, a grinding process is carried out before dividing the workpiece 11, in which a grinding wheel is brought into contact with the back side of the workpiece 11 to thin it. However, after the grinding process, curved scratches (grinding marks, saw marks) formed along the path of movement of the grinding wheel remain on the back side of the workpiece 11. The remaining grinding marks cause a decrease in the flexural strength of the device chip.

Therefore, the back side of the workpiece 11 after grinding is polished using the above-mentioned polishing pad 12. This removes the grinding marks remaining on the back side of the workpiece 11, and prevents a decrease in the flexural strength of the device chip.

Figure 2 is a plan view showing the polishing layer 14 of the polishing pad 12. The polishing layer 14 includes a first polishing layer 16 and a second polishing layer 18. Figure 2 shows an example in which the polishing layer 14 is divided into four parts, each including two first polishing layers 16 and two second polishing layers 18. For example, the first polishing layer 16 and the second polishing layer 18 are formed in a fan shape extending from the center of the polishing layer 14 to the outer periphery, and are alternately arranged along the circumferential direction of the polishing layer 14 so as to share a common center.

The upper surface of the first polishing layer 16 constitutes a flat first polishing surface 16a that contacts the workpiece 11 during polishing. Similarly, the upper surface of the second polishing layer 18 constitutes a flat second polishing surface 18a that contacts the workpiece 11 during polishing. The thicknesses of the first polishing layer 16 and the second polishing layer 18 are approximately equal, and the first polishing surface 16a and the second polishing surface 18a are disposed on approximately the same plane.

The hardness of the first abrasive layer 16 is higher than that of the second abrasive layer 18. Therefore, the abrasive layer 14 is configured such that regions of high hardness and regions of low hardness are arranged alternately along the circumferential direction of the abrasive layer 14. For example, by appropriately changing the porosity and material of the first abrasive layer 16 and the second abrasive layer 18, the first abrasive layer 16 and the second abrasive layer 18 having the desired hardness can be obtained.

As shown in FIG. 1, when the workpiece 11 is brought into contact with the polishing layer 14 while rotating the polishing pad 12, the workpiece 11 moves relative to the polishing layer 14 in the circumferential direction of the polishing layer 14. As a result, the workpiece 11 alternately comes into contact with the first polishing layer 16, which has a high hardness, and the second polishing layer 18, which has a low hardness.

Here, it has been confirmed that the hardness of the polishing layer 14 of the polishing pad 12 affects the processing conditions and processing results in the polishing process. Specifically, if the hardness of the polishing layer 14 is high, the polishing time required to remove the grinding marks is shortened, but the surface roughness of the workpiece 11 after polishing increases, and the quality of the workpiece 11 deteriorates. On the other hand, if the hardness of the polishing layer 14 is low, the surface roughness of the workpiece 11 after polishing is reduced, but the polishing time required to remove the grinding marks is long. Therefore, if the polishing layer 14 is a single layer, it is difficult to achieve both a shortened polishing time and an improved quality of the workpiece.

On the other hand, as shown in FIG. 2, when the polishing layer 14 includes a first polishing layer 16 having a high hardness and a second polishing layer 18 having a low hardness, the polishing time is shortened by polishing with the first polishing layer 16, and the surface roughness of the workpiece 11 is reduced by polishing with the second polishing layer 18. This makes it possible to achieve a high level of both shortening the polishing time and improving the quality of the workpiece 11.

For example, consider the case where the workpiece 11 having an uneven surface is polished by contacting both the first polishing layer 16 and the second polishing layer 18. In this case, the first polishing layer 16, which has a high hardness, polishes the convex parts of the unevenness formed on the surface of the workpiece 11 preferentially. This allows the height of the convex parts to be efficiently reduced in a short polishing time. In addition, when the convex parts are lowered, the second polishing layer 18, which has a low hardness and is flexible, is more likely to enter between the adjacent convex parts (concave parts). Then, the second polishing layer 18 contacts the surface of the workpiece 11, the height difference of which has been reduced by the first polishing layer 16, so as to follow the unevenness, and the entire surface of the workpiece 11 is polished by the second polishing layer 18. As a result, the surface of the workpiece 11 is flattened. It is presumed that the synergistic effect of the first polishing layer 16 and the second polishing layer 18 shortens the polishing time of the workpiece 11 and effectively reduces the surface roughness of the workpiece 11.

The hardness of the first polishing layer 16 is appropriately set so that the polishing time is reduced to a certain level or less. The hardness of the second polishing layer 18 is appropriately set so that the surface roughness of the workpiece 11 after polishing is reduced to a certain level or less. Specifically, the hardness of the first polishing layer 16 measured by a durometer type D is preferably 41 or more and 70 or less. The hardness of the second polishing layer 18 measured by a durometer type D is preferably 25 or more and 40 or less.

As described above, the polishing pad 12 according to this embodiment includes a polishing layer 14 containing a resin having air holes, and the polishing layer 14 includes a first polishing layer 16 and a second polishing layer 18 that have different hardnesses. By polishing a workpiece with the polishing pad 12, it is possible to obtain a high-quality workpiece while shortening the polishing time.

Note that while FIG. 2 shows an example of a configuration in which the polishing layer 14 is divided into four, there is no limit to the number of divisions of the polishing layer 14, i.e., the number of first polishing layers 16 and second polishing layers 18 contained in the polishing layer 14. FIG. 3(A) is a plan view showing a polishing layer 14 (polishing layer 14A) divided into eight, and FIG. 3(B) is a plan view showing a polishing layer 14 (polishing layer 14B) divided into 16.

The polishing layer 14A has four first polishing layers 16 and four second polishing layers 18 formed in a fan shape, and the first polishing layers 16 and the second polishing layers 18 are arranged alternately along the circumferential direction of the polishing layer 14A so as to share a center. The polishing layer 14B has eight first polishing layers 16 and eight second polishing layers 18 formed in a fan shape, and the first polishing layers 16 and the second polishing layers 18 are arranged alternately along the circumferential direction of the polishing layer 14B so as to share a center.

In addition, when the workpiece 11 is polished by the polishing layer 14 (see FIG. 1), as long as the workpiece 11 can come into contact with both the first polishing layer 16 and the second polishing layer 18, there are no limitations on the shape and arrangement of the first polishing layer 16 and the second polishing layer 18. For example, the first polishing layer 16 and the second polishing layer 18 may be formed in a shape other than a sector shape.

Figure 4 (A) is a plan view showing the polishing layer 14 (polishing layer 14C) having a rectangular first polishing layer 16 and a second polishing layer 18. For example, the first polishing layer 16 and the second polishing layer 18 are formed in a square or rectangular shape and are arranged alternately along two mutually perpendicular directions (directions parallel to the outer edges of the first polishing layer 16 and the second polishing layer 18). That is, the four sides of the first polishing layer 16 are adjacent to the second polishing layer 18, and the four sides of the second polishing layer 18 are adjacent to the first polishing layer 16. Therefore, the polishing layer 14C has a structure in which the first polishing layer 16 and the second polishing layer 18 are arranged in a checkerboard pattern.

Figure 4 (B) is a plan view showing the polishing layer 14 (polishing layer 14D) having a band-shaped (linear) first polishing layer 16 and second polishing layer 18. As shown in Figure 4 (B), the first polishing layer 16 and the second polishing layer 18 are arranged so that their length direction is along the first direction (up and down direction on the paper) and their width direction is along the second direction (left and right direction on the paper) perpendicular to the first direction. In addition, the first polishing layers 16 and the second polishing layers 18 are arranged alternately along the second direction.

In the polishing layers 14C and 14D, the first polishing layer 16 and the second polishing layer 18 are also arranged alternately along the circumferential direction of the polishing layers 14C and 14D. Therefore, even when the workpiece 11 is polished with the polishing layers 14C and 14D (see FIG. 1), the workpiece 11 comes into contact with both the first polishing layer 16 and the second polishing layer 18.

In addition, the structure of the polishing pad 12 according to this embodiment, the method of polishing the workpiece 11, etc. can be appropriately modified without departing from the scope of the purpose of the present invention. For example, the shape and size of the first polishing layer 16 and the second polishing layer 18 included in the polishing layer 14 of the polishing pad 12 according to this embodiment may be different from each other.

Next, a workpiece was polished using the polishing pad according to this embodiment, and the results of evaluating the polishing time and the quality of the workpiece are described. In this evaluation, a workpiece on which grinding marks were formed by grinding was polished using a polishing pad including a first polishing layer and a second polishing layer, and the polishing time required to remove the grinding marks and the surface roughness (Ra) of the wafer after polishing were measured.

The workpieces used were silicon wafers with a diameter of 200 mm. First, three silicon wafers were prepared, and the backside of each silicon wafer was subjected to a grinding process using a grinding wheel to thin the silicon wafer. After the grinding process, curved grinding marks formed along the path of the grinding wheel remained on the backside of the silicon wafer.

Next, the backsides of the three silicon wafers with the remaining grinding marks were polished using three types of polishing pads. The polishing pads used were two types of polishing pads (polishing pads A and B) according to the comparative example and one type of polishing pad (polishing pad C) according to the example. Each of the polishing pads A, B, and C used a disk-shaped polishing layer (diameter 450 mm, thickness 3 to 4 mm) in which abrasive grains (average grain size 100 nm) made of silica (SiO ₂ ) were held by a binder mainly composed of polyurethane.

For the polishing pads A and B of the comparative example, a polishing pad with a single polishing layer was used. On the other hand, for the polishing pad C of the example, a polishing pad was used in which the polishing layer was divided into eight parts, and the first polishing layer and the second polishing layer were formed in a sector shape, each of which had four pieces (see FIG. 3(A)). Table 1 shows the hardness of the polishing layers included in the polishing pads A, B, and C. A type D durometer was used to measure the hardness.

A polishing device 2 (see Figure 1) was used to polish the silicon wafer. The rotation speed of the polishing pad was set to 90 rpm, and the rotation speed of the silicon wafer was set to 95 rpm. The force (load) of pressing the polishing pad against the silicon wafer was set to 30 kPa. Furthermore, a slurry containing an inorganic alkali was used as the polishing liquid, and the flow rate of the polishing liquid was set to 200 ml/min.

The polishing process was continued until the grinding marks remaining on the back side of the silicon wafer were removed. The polishing time of the silicon wafer required to remove the grinding marks and the amount of silicon wafer removed (reduction in thickness) were then measured. The polishing rate was calculated based on the polishing time and amount of silicon wafer removed. Furthermore, the surface roughness (Ra) of the back side of the silicon wafer after polishing was measured. The measurement results are shown in Table 2.

As shown in Table 2, when polishing pad A with a high hardness polishing layer was used, the polishing time and removal amount of the silicon wafer were reduced, but the surface roughness of the silicon wafer increased. When polishing pad B with a low hardness polishing layer was used, the surface roughness of the silicon wafer was reduced, but the polishing time and removal amount of the silicon wafer increased.

On the other hand, when polishing pad C, which has a high-hardness polishing layer and a low-hardness polishing layer, was used, the polishing time and amount of silicon wafer required to remove the grinding marks were kept to the same level as when polishing pad A was used, and a high polishing rate was achieved. Furthermore, the surface roughness of the silicon wafer was kept to the same level as when polishing pad B was used.

The above evaluation results confirm that by using the polishing pad according to this embodiment, it is possible to achieve a high level of both reducing the polishing time (amount removed) and improving the quality of the workpiece after polishing.

11 Workpiece 2 Polishing device 4 Support unit 6 Support table (platen)
6a Support surface 8 Spindle 10 Rotation drive source 12 Polishing pad 14, 14A, 14B, 14C, 14D Polishing layer 16 First polishing layer 16a First polishing surface 18 Second polishing layer 18a Second polishing surface 20 Holding unit 22 Holding part 24 Spindle 26 Driving mechanism 28 Supply unit 30 Nozzle 32 Polishing liquid

Claims (7)

A polishing pad for polishing a workpiece, comprising:
A disc-shaped polishing layer containing a resin having pores is provided,
The abrasive layer comprises a first abrasive layer including a first abrasive surface in contact with the workpiece, and a second abrasive layer including a second abrasive surface in contact with the workpiece;
the hardness of the first abrasive layer, as measured by a durometer type D, is 41 or more and 70 or less;
A polishing pad, characterized in that the hardness of the second polishing layer, as measured by a durometer type D, is 25 or more and 40 or less . The polishing pad according to claim 1, characterized in that the first polishing layer and the second polishing layer are alternately provided along the circumferential direction of the polishing layer. The polishing pad according to claim 1 or 2, characterized in that the first polishing layer and the second polishing layer are formed in a fan shape extending from the center to the outer periphery of the polishing layer. The polishing pad according to any one of claims 1 to 3, characterized in that the polishing layer comprises a plurality of the first polishing layers and a plurality of the second polishing layers. The polishing layer comprises a plurality of the first polishing layers and a plurality of the second polishing layers;
2. The polishing pad according to claim 1, wherein the first polishing layer and the second polishing layer are arranged alternately along two directions perpendicular to each other. The polishing layer comprises a plurality of the first polishing layers and a plurality of the second polishing layers;
2. The polishing pad of claim 1, wherein the first polishing layer and the second polishing layer are in the form of strips and arranged alternately. The resin is polyurethane,
7. The polishing pad according to claim 1, wherein the first polishing layer and the second polishing layer have different porosities.

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