Polishing pad manufacturing method

Abstract

To provide a method for manufacturing a polishing pad which can easily adjust a position of a member for an end point detection window while suppressing positional deviation or the like of the member for the end point detection window.SOLUTION: A method for manufacturing a polishing pad having a polishing layer with an end point detection window includes a curing step of fixing a member for an end point detection window into a mold, curing a curable resin in the state of being brought into contact with the member for the end point detection window, and forming a resin sheet in which the member for the end point detection window is incorporated, and a slice step of slicing the resin sheet and forming a polishing layer, wherein in the curing step, the member for the end point detection window is suspended and fixed by a position fixing jig installed in the mold upper part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a polishing pad. [Background technology]

[0002] In semiconductor manufacturing processes, chemical mechanical polishing (CMP) is used for planarization after insulating film deposition and for forming metal wiring. One of the important technologies required for chemical mechanical polishing is polishing endpoint detection, which detects whether the polishing process is complete. For example, over-polishing or under-polishing relative to the target polishing endpoint directly leads to product defects. Therefore, in chemical mechanical polishing, the amount of polishing must be strictly controlled by polishing endpoint detection.

[0003] Chemical mechanical polishing is a complex process, and the polishing speed (polishing rate) varies depending on the operating conditions of the polishing equipment, the quality of consumables (slurry, polishing pads, dressers, etc.), and variations in conditions over time during the polishing process. Furthermore, in recent years, the precision of remaining film thickness and in-plane uniformity required in semiconductor manufacturing processes have become increasingly strict. For these reasons, detecting the polishing endpoint with sufficient precision has become more difficult.

[0004] The main methods for detecting the polishing endpoint include the optical endpoint detection method, the torque endpoint detection method, and the eddy current endpoint detection method. In the optical endpoint detection method, the endpoint is detected by irradiating the wafer with light through a transparent window member provided on the polishing pad and monitoring the reflected light.

[0005] As an example of a method for manufacturing a polishing pad using such an optical endpoint detection method, Patent Document 1 discloses a method for manufacturing a polishing pad in which a liner is provided on the bottom surface of a mold to fix a window block, and then a curable material is filled into the mold and cured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-197597 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the method of fixing the window block at the bottom of the mold as in Patent Document 1, if the liner deforms due to heat during curing, the window block cannot be fixed perpendicularly to the mold, which is a problem. Also, because the window block is fixed directly to the liner, it is difficult to reuse, which raises manufacturing costs.

[0008] Furthermore, in Patent Document 1, a window adhesive is used to bond the window block to the top surface of the liner, but with this type of bonding method, when the hardenable material is loaded into the mold cavity, there is a risk that the window block may tilt or become misaligned (hereinafter collectively referred to as ``misalignment, etc.'') due to the flow of the hardenable material or the expansion or contraction of the hardenable material when it hardens.

[0009] Furthermore, when placing a relatively small component for an end-point detection window in an accurate position, the position of the window must be fine-tuned, but if the window is fixed using a window adhesive, the position cannot be adjusted thereafter, which reduces the manufacturing yield of good products.

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method for manufacturing a polishing pad that can suppress positional shifts of the end point detection window member while also making it easy to adjust the position of the end point detection window member. [Means for solving the problem]

[0011] That is, the present invention is as follows. [1] A method for manufacturing a polishing pad having a polishing layer with an endpoint detection window, comprising: a curing step of fixing an end point detection window member in a mold and curing the curable resin in contact with the end point detection window member to form a resin sheet incorporating the end point detection window member; a slicing step of slicing the resin sheet to form an abrasive layer, In the curing step, the end-point detection window member is clamped by clamping portions of a position fixing jig installed on the upper part of the mold, thereby being suspended and fixed. A method for manufacturing a polishing pad. [2] In the curing step, after filling the mold with a curable resin, the end-point detection window member is brought into contact with the curable resin to cure the curable resin. A method for manufacturing the polishing pad described in [1]. [3] In the curing step, the end point detection window member is fixed in the mold, and then a curable resin is filled in the mold and cured. A method for manufacturing the polishing pad described in [1]. [4] the position fixing jig has a through hole through which the end point detection window member is inserted, the clamping portion clamps the end-point detection window member inserted into the through-hole; A method for producing the polishing pad according to any one of [1] to [3]. [5] the clamping portion detachably clamps the end-point detection window member; A method for producing the polishing pad according to any one of [1] to [4]. [6] The position fixing jig has a first fitting portion that fits with the upper part of the mold. A method for producing a polishing pad according to any one of [1] to [5]. [7] The mold has a second fitting portion that fits with the position fixing jig. A method for producing a polishing pad according to any one of [1] to [6]. [8] a groove forming step of forming grooves on the polishing surface of the polishing layer, No groove processing is performed on the exposed portion of the end point detection window member before the groove forming step. A method for producing the polishing pad according to any one of [1] to [7]. [9] a lamination step of laminating a base layer and / or a cushion layer on the surface of the polishing layer opposite to the polishing surface, A method for producing a polishing pad according to any one of [1] to [8]. [Effects of the Invention]

[0012] According to the present invention, a method for manufacturing a polishing pad can be provided that can suppress positional deviation of the end point detection window member while also allowing the position of the end point detection window member to be easily adjusted. [Brief explanation of the drawings]

[0013] [Figure 1] 10 is a perspective view showing an example in which the end-point detection window member of the present embodiment is clamped by a clamping portion. FIG. [Figure 2] 10 is a perspective view showing another example in which the end-point detection window member of the present embodiment is clamped by the clamping portion. FIG. [Figure 3] FIG. 2 is a top view showing one embodiment of a combination of a mold and a position fixing jig for producing a resin sheet used in this embodiment. [Figure 4] FIG. 10 is a top view showing another embodiment in which a mold and a position fixing jig are combined to produce a resin sheet used in this embodiment. [Figure 5] 4 is a cross-sectional view showing the AA' cross section of the mold shown in FIG. 3 before the hardening resin is poured into the mold. FIG. [Figure 6] 4 is a cross-sectional view showing the AA' cross section of the mold shown in FIG. 3 after a curable resin has been poured into it. FIG. [Figure 7] FIG. 3 is a top view showing the resin sheet obtained after the curing process. [Figure 8] 10 is a cross-sectional view of the vicinity of the end point detection window of the resin sheet obtained after the curing process. FIG. [Figure 9] 1 is a schematic perspective view of a polishing pad according to an embodiment of the present invention. [Figure 10] 3 is a schematic cross-sectional view of an end point detection window portion of the polishing pad of the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0015] 1. Manufacturing method of polishing pad The method for manufacturing a polishing pad of this embodiment includes a curing process in which an end point detection window member is fixed in a mold and a curable resin is cured while in contact with the end point detection window member to form a resin sheet incorporating the end point detection window member, and a slicing process in which the resin sheet is sliced to form a polishing layer.In the curing process, the end point detection window member is clamped by the clamping portion of a position fixing jig installed on the top of the mold, and is thereby hung and fixed, thereby manufacturing a polishing pad having a polishing layer with an end point detection window.

[0016] In this way, by clamping the endpoint detection window member with the clamping portion of the position fixing jig installed on the top of the mold, the endpoint detection window member can be fixed more firmly than with adhesive, etc. Therefore, displacement of the endpoint detection window member due to the flow of the curable resin or the expansion or contraction of the curable material when curing is more effectively suppressed. Furthermore, while the endpoint detection window member may be fixed at an angle when fixed with adhesive, etc., by clamping the endpoint detection window member with the clamping portion, the endpoint detection window member can be fixed vertically.

[0017] Furthermore, when the end point detection window member is fixed to the bottom surface of the mold with adhesive or the like, its position cannot be adjusted once it is fixed. However, by suspending and fixing the end point detection window member using a clamping unit, the end point detection window member can be easily removed. The clamping unit can be loosened and the embedded position of the end point detection window member can be fine-tuned until the curable resin hardens. Because end point detection windows typically do not have polishing capabilities, it is preferable that the size of the window placed in the polishing pad be as small as possible. To accurately deliver transmitted light to the detector of the polishing device through a small end point detection window, the window must be precisely positioned in the same location on each polishing pad. Therefore, enabling such fine adjustments can also improve the yield rate. Furthermore, after the curable resin hardens, the clamping unit can be loosened and the end point detection window member can be removed from the clamping unit to separate the position fixing jig and the resulting resin sheet.

[0018] Furthermore, since the component for the endpoint detection window is attached to the position fixing jig rather than the mold, there is no need to process the mold itself, and a conventional one can be used as is.Furthermore, the position fixing jig can be used multiple times, so it does not need to be disposable like a liner.

[0019] 1.1.Curing process The curing process is a process in which a component for an end point detection window is fixed in a mold, and the curable resin is cured while in contact with the component for an end point detection window to form a resin sheet incorporating the component for an end point detection window.

[0020] 1.1.1.End-point detection window component First, prior to the curing step, an endpoint detection window member 10 is prepared. The shape of the endpoint detection window member 10 is not particularly limited, but examples thereof include a rectangular parallelepiped and a cylindrical shape, as shown in Figures 1 and 2.

[0021] 1, the rectangular parallelepiped endpoint detection window member 10 has sides that are easy to clamp, allowing it to be more stably fixed to the position fixing jig 30. The shape of the rectangular parallelepiped endpoint detection window member 10 is not particularly limited as long as it is configured as a window member of the required size, but for example, the end face in the hanging direction may have a convex shape. Such a convex shape makes it easier for the curable resin to flow between the end face of the endpoint detection window member 10 and the bottom surface 21 of the mold 20, preventing air bubbles from being trapped in the curable resin.

[0022] As shown in FIG. 2 , the cylindrical endpoint detection window member 10 can have, for example, a pillar portion 11 and a base portion 12. Here, the pillar portion 11 is embedded in a resin sheet 50 after the curing process to form an endpoint detection window 51. The cross-sectional shape of the pillar portion 11 is not particularly limited and may be circular or polygonal, and the tip of the pillar portion 11 may have a convex shape. Furthermore, the base portion 12 may be configured to be wider than the diameter of the hole in the clamping portion 31 of the position fixing jig 30. In this way, when the endpoint detection window member 10 is inserted into the clamping portion 31 of the position fixing jig 30 from above, it is locked by the base portion 12, and the cylindrical endpoint detection window member 10 is fixed in place without falling off.

[0023] In this way, by configuring the cylindrical endpoint detection window member 10 to have a shape including a pillar portion 11 and a base portion 12, the pillar portion 11 can be made relatively small within the range necessary for the endpoint detection window, while the base portion 12 can further prevent it from falling off. This tends to prevent the endpoint detection window member 10 from being displaced or tilted due to the resin injected during the curing process or the resin being cured. Furthermore, because the pillar portion 11 can be configured relatively small within the range necessary for the endpoint detection window, the impact of embedding the endpoint detection window on the polishing characteristics of the polishing pad can be further reduced. Note that the shape of the endpoint detection window member 10 is not limited to that shown in FIG. 2 . The cylindrical endpoint detection window member 10 may have only the pillar portion 11 without the base portion 12.

[0024] The endpoint detection window member 10 can be produced, for example, by injecting a resin into a mold (not shown), without any particular limitation. After the endpoint detection window member 10 is removed from the mold, the side surfaces are preferably treated with sandpaper or a solvent. This allows the release agent to be removed if it is present on the endpoint detection window member 10. Furthermore, roughening the side surfaces with sandpaper tends to improve adhesion between the resin sheet 50 and the endpoint detection window member 10 (endpoint detection window 51) when the endpoint detection window member 10 is embedded in the resin sheet 50.

[0025] 1.1.2. Positioning fixture The position fixing jig 30 is not particularly limited as long as it has a clamping portion 31, can be installed above the mold 20, and can suspend and fix the end point detection window member 10 by the clamping portion 31. As shown in Figures 5 and 6, the end point detection window member 10 is suspended and fixed by the clamping portion 31 of this position fixing jig 30.

[0026] For example, when the end point detection window members 10 are fixed to the bottom surface of the mold 20, it is difficult to change the number or position of the end point detection window members 10 after the mold is filled with curable resin. On the other hand, when the end point detection window members 10 are fixed by hanging as in this embodiment, it is easy to change the position or number of the end point detection window members 10 even after the mold 20 has been filled with curable resin but before it has hardened.

[0027] Furthermore, there is no need to make any other modifications to the mold itself, such as the bottom of the mold 20, in order to fix the end point detection window member 10, and the mold 20 can be the same as the one used to manufacture polishing pads that do not have an end point detection window.

[0028] Furthermore, the clamping portion 31 is not particularly limited as long as it clamps and fixes the endpoint detection window member 10. By clamping the side surfaces of the endpoint detection window member 10 with such clamping portion 31, the endpoint detection window member 10 can be suspended and fixed vertically, and displacement or the like is less likely to occur even when a force is applied in the planar direction. This prevents the endpoint detection window member 10 from failing to function as an endpoint detection window if it is fixed at an angle rather than vertically, or from being pushed out of position by the flow of the curable material or the expansion or contraction of the curable material during curing. This effect is particularly significant compared to a method in which the endpoint detection window member 10 is fixed on only one side with, for example, an adhesive.

[0029] Furthermore, by using the clamping unit 31, there is no need to use a fixing means such as an adhesive, and the endpoint detection window member 10 can be easily attached and detached. For example, if an adhesive or the like is used, there is a concern that misalignment or detachment may occur if the adhesive strength is weak, and if the adhesive strength is strong, it may be difficult to remove the endpoint detection window member 10 from the position fixing jig 30 after the curing process. In contrast, when the clamping unit 31 is used, it is sufficient to clamp the endpoint detection window member 10 from at least one direction, and by weakening the clamping force, it can be easily attached and detached. Furthermore, when an adhesive is used, it is necessary to perform processing such as sanding the adhesive surface of the endpoint detection window member 10 with sandpaper to make it flat, but using the clamping unit 31 eliminates such processing.

[0030] The clamping portion 31 is not particularly limited as long as it clamps and fixes the endpoint detection window member 10 as described above, and may have one or more members that clamp the endpoint detection window member 10, and may further have an adjustment portion 32 for adjusting the clamping force. Among these, from the viewpoint of ease of attachment and detachment, a clamping portion 31 configured so that it can clamp the endpoint detection window member 10 simply by fitting it in is preferred, and a clamping portion 31 including an adjustment portion 32 is preferred because the fixing strength can be adjusted.

[0031] Such an adjustment unit 32 may be, for example, a screw or a spring that tightens a plurality of members (clamping units 31) that clamp the endpoint detection window member 10 as shown in Fig. 1. In Fig. 1, the clamping units 31, which are made up of two members, are connected via the adjustment unit 32 (screw), and the adjustment unit 32 can adjust the distance between the clamping units 31, which are made up of two members. As a result, by tightening the clamping units 31 with the adjustment unit 32 so as to shorten the distance between the clamping units 31, the side surfaces of the endpoint detection window member 10 are pressed down, and the clamping force is adjusted.

[0032] The adjustment part 32 may be, for example, a screw or a spring that fastens the end point detection window member 10 together with the clamping part 31 as shown in Fig. 2. In Fig. 2, the bottom of the adjustment part 32 (screw) that penetrates from the side of the clamping part 31 presses against the side of the end point detection window member 10, and the clamping force is thereby adjusted by the pressing force between the inner wall of the clamping part 31 and the bottom of the adjustment part 32 (screw).

[0033] The shapes of the clamping portion 31 and the adjustment portion 32 are not limited to those described above, and they can have any other structure as long as they are configured to be able to increase or decrease the clamping force.

[0034] The position fixing jig 30 may have a through hole 33 through which the end point detection window member 10 is inserted, and in this case, the clamping portion 31 may clamp the end point detection window member 10 inserted into the through hole 33. By inserting the end point detection window member 10 into the through hole 33 provided in advance in the position fixing jig 30 and clamping it in this way, positioning can be easily performed according to the through hole 33.

[0035] The clamping portion 31 can clamp the endpoint detection window member 10 so that it can be attached and detached more easily. This makes it easy to remove the endpoint detection window member 10, and the embedding position of the endpoint detection window member 10 can be fine-tuned by loosening the clamping portion 31 until the curable resin hardens. Therefore, such fine adjustments can also improve the manufacturing yield. Furthermore, after the curable resin hardens, the clamping portion 31 can be loosened and the endpoint detection window member 10 can be removed from the clamping portion 31, allowing the position fixing jig 30 and the resulting resin sheet 50 to be separated.

[0036] 3 and 4 show top views of a mold 20 for producing a resin sheet, and Fig. 5 shows a cross-sectional view taken along line A-A' in Fig. 3 before a curable resin is poured into the mold 20. The mold 20 shown in Figs. 3 to 5 includes a position fixing jig 30 that fixes the endpoint detection window member 10 of the embodiment shown in Fig. 2 using an adjustment unit 32 of the embodiment shown in Fig. 4. As shown in Figs. 3 and 5, the position fixing jig 30 is installed above the mold 20, and the endpoint detection window member 10 is clamped by clamping units 31 of the position fixing jig 30, thereby being suspended and fixed vertically downward.

[0037] The shape of the mold 20 is not particularly limited, but may be, for example, a flat mold for forming a resin sheet, or a rectangular mold for forming a resin block for cutting out a resin sheet. The position fixing jig 30 is fixed in contact with the side wall 22 so as to cover the upper part of the mold 20.

[0038] The location of the position fixing jig 30 that comes into contact with the mold 20 may have an uneven shape (first fitting portion) that can fit with the upper part of the mold 20. Furthermore, the location of the mold 20 that comes into contact with the position fixing jig 30 may also have an uneven shape (second fitting portion) that can fit with the position fixing jig 30. This makes it easier to position the position fixing jig 30 when installing it on the mold 20, and tends to prevent the embedded position of the endpoint detection window member 10 from shifting during each curing process.

[0039] The material of the position fixing jig 30 is not particularly limited, but may be a heat-resistant material that is not deformed by the heat of the hardening process, such as aluminum alloy or stainless steel.

[0040] 1.1.3.Curing resin In the curing step, the endpoint detection window member 10 is fixed in the mold 20 as described above, and the curable resin 40 is cured while in contact with the endpoint detection window member 10 to form a resin sheet 50 incorporating the endpoint detection window member 10 (endpoint detection window 51). Figure 4 shows a cross-sectional view of A-A' in Figure 2 after the curable resin has been injected into the mold 20.

[0041] In this embodiment, the manner in which the curable resin 40 is cured while in contact with the end point detection window member 10 is not particularly limited, and the end point detection window member 10 may be fixed in the mold 20 as shown in Figure 3, and then the mold 20 may be filled with the curable resin 40 and the curable resin 40 may be cured, or the mold 20 may be filled with the curable resin 40, and then the end point detection window member 10 may be brought into contact with the curable resin, and then the curable resin 40 may be cured.

[0042] The curable resin is not particularly limited, but examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more. Such polyurethane resins can be synthesized from polyisocyanate and polyol.

[0043] 1.2.Slicing process The slicing step is a step of slicing the resin sheet to form a polishing layer. Figures 7 and 8 show a top view and a cross-sectional view of the resin sheet 50 obtained after the curing step, by removing it from the mold 20 and removing the base portion 12. As shown in Figures 7 and 8, the resin sheet has an endpoint detection window member embedded therein.

[0044] The slicing method is not particularly limited, but an example is a method in which a resin sheet as shown in Figures 7 and 8 is cut in the surface direction to obtain a polishing pad of any thickness. Also, as shown in Figure 9, a rectangular polishing pad may be cut into a circular shape.

[0045] 1.3.Groove formation process The method for manufacturing a polishing pad of this embodiment may optionally include a groove forming step of forming grooves on the polishing surface of the polishing layer (see FIG. 10). Note that it is preferable not to perform groove processing on the exposed portion of the end-point detection window member, as this would interfere with optical end-point detection.

[0046] 1.4.Other processes The method for producing a polishing pad of this embodiment may optionally include a lamination step of laminating a base layer and / or a cushion layer on the surface of the polishing layer opposite the polishing surface.

[0047] 2. Polishing pad Fig. 9 shows a schematic perspective view of the polishing pad of this embodiment, and Fig. 10 shows a cross-sectional view of the periphery of the endpoint detection window 51 in Fig. 9. As shown in Fig. 10, the polishing pad of this embodiment has a resin sheet 50 (polishing layer) and an endpoint detection window 51, and may have a cushion layer 52 on the side opposite to the polishing surface 50a, as necessary.

[0048] As shown in Fig. 10, an adhesive layer 53 may be provided between the resin sheet 50 (polishing layer) and the cushion layer 52, and an adhesive layer 54 may be provided on the surface of the cushion layer 52. The polishing surface 50a of the polishing pad of this embodiment may be flat, or may have an uneven surface with grooves 55 formed therein, as shown in Fig. 10. The grooves 55 may be formed in a variety of shapes, such as a plurality of concentric circles, a lattice pattern, or a radial pattern, either alone or in combination.

[0049] The end point detection window 51 is a transparent member provided in an opening in the resin sheet 50 (polishing layer), and serves as a transmission path for light from the film thickness detection sensor in optical end point detection. In this embodiment, the end point detection window is circular, but may be square, rectangular, polygonal, elliptical, or other shapes as needed.

[0050] The resin sheet 50 (polishing layer) is not particularly limited, but may be, for example, a polyurethane sheet. This polyurethane sheet has an opening in which an end-point detection window is embedded. The location of the opening is not particularly limited, but it is preferable to provide it at a radial position corresponding to a film thickness detection sensor installed on the table of the polishing apparatus. Furthermore, the number of openings is not particularly limited, but it is preferable to have multiple openings at similar radial positions so that the window passes over the film thickness detection sensor multiple times during one rotation of the polishing pad attached to the table. [Industrial Applicability]

[0051] The method for producing a polishing pad of the present invention has industrial applicability as an efficient method for producing a polishing pad suitable for an optical endpoint detection method. [Explanation of symbols]

[0052] 10...End point detection window member, 11...Columnar portion, 12...Pedestal portion, 20...Mold, 21...Bottom surface, 22...Side wall, 30...Position fixing jig, 31...Clip portion, 32...Adjustment portion, 40...Hardening resin, 50...Resin sheet, 50a...Polished surface, 51...End point detection window, 52...Cushion layer, 53...Adhesive layer, 54...Adhesive layer, 55...Groove

Claims

1. A method for manufacturing a polishing pad having a polishing layer with an endpoint detection window, comprising: a curing step of fixing an end point detection window member in a mold and curing the curable resin in contact with the end point detection window member to form a resin sheet incorporating the end point detection window member; a slicing step of slicing the resin sheet to form an abrasive layer, In the curing step, the end-point detection window member is clamped by clamping portions of a position fixing jig installed on the upper part of the mold, thereby being suspended and fixed; the position fixing jig has a through hole through which the end point detection window member is inserted, the clamping portion clamps the end-point detection window member inserted into the through-hole; A method for manufacturing a polishing pad.

2. In the curing step, after filling the mold with a curable resin, the end-point detection window member is brought into contact with the curable resin to cure the curable resin. The method for producing the polishing pad according to claim 1 .

3. In the curing step, the end point detection window member is fixed in the mold, and then a curable resin is filled in the mold and cured. The method for producing the polishing pad according to claim 1 .

4. the clamping portion detachably clamps the end-point detection window member; The method for producing a polishing pad according to any one of claims 1 to 3.

5. the position fixing jig has a first fitting portion that fits with the upper part of the mold; The method for producing the polishing pad according to any one of claims 1 to 4.

6. the mold has a second fitting portion that fits with the position fixing jig; The method for producing the polishing pad according to any one of claims 1 to 5.

7. a groove forming step of forming grooves on the polishing surface of the polishing layer, No groove processing is performed on the exposed portion of the end point detection window member before the groove forming step. The method for producing the polishing pad according to any one of claims 1 to 6.

8. a lamination step of laminating a base layer and / or a cushion layer on the surface of the polishing layer opposite to the polishing surface, The method for producing the polishing pad according to any one of claims 1 to 7.

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