Polishing pad and method for manufacturing polishing pad

Abstract

To provide a polishing pad excellent in processing efficiency in both a wide area and a local area to the surface of a workpiece.SOLUTION: The polishing pad is used for CARE or mechanical polishing by carrying a catalyst layer 11 for CARE or abrasive grains for mechanical polishing on a surface of a pad base body 10, and the pad base body 10 is composed of a polymer foam 2 integrally molded by using the same material, and has a hard layer 22 having a relatively small porosity in a partial area reaching its surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing pad used for catalyst surface-based etching polishing and mechanical polishing, and a method for manufacturing the same. [Background technology]

[0002] Catalyst-Referred Etching (CARE) is a surface polishing method based on the principle of pure chemical etching, which uses catalytic action to induce a hydrolysis reaction using pure water as the processing fluid, without using abrasive particles, and can atomically smooth the surfaces of various materials without introducing material damage. Because no abrasive particles or chemicals are used, the issue of waste disposal is resolved, and it is also expected to be a sustainable technology.

[0003] CARE uses a catalytic pad, which moves the catalyst and the workpiece surface relative to each other while in contact with each other to allow etching to proceed. When CARE was first developed, a catalytic pad with a thin catalytic film on the surface of a hard metal pad substrate was used. However, if the surface of the pad substrate is too hard, selectivity to convex portions increases, making it difficult to process a wide area of ​​the sample, and this reduces processing efficiency, especially for workpieces with undulating surfaces.

[0004] Therefore, in order to ensure uniform contact between a catalytic pad and a large, undulating workpiece, such as a semiconductor wafer or a glass substrate for a mask blank, a catalytic pad has been developed that uses a soft material, such as rubber, as the pad substrate and provides a thin catalytic film on the surface. The catalyst is typically a transition metal, and the catalytic pad is fabricated by forming a film on the surface of a soft substrate, such as rubber, using a sputtering method (see Patent Documents 1, 2, 3, and 4). However, such soft pad substrates have low selectivity to protruding portions and tend to adhere to the entire surface of the workpiece, preventing efficient and clean etching in localized areas. For example, when polishing polycrystalline materials such as YAG ceramics, which have different crystal orientations and are prone to grain boundary steps, it takes a long time to obtain a clean overall surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013-084934 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-149351 [Patent Document 3] International Publication No. 2015-159973 [Patent Document 4] Patent Publication No. 2021-115692 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, the present invention aims to solve the problem by providing a polishing pad that has excellent processing efficiency both over a wide area and in a local area on the surface of a workpiece. [Means for solving the problem]

[0007] In light of this current situation, the inventors conducted a study and came up with the idea that by using a soft material as a base and then bonding a hard material to the surface, it might be possible to efficiently process localized areas while still fitting well to the entire surface of the workpiece. However, with such a bonding of different materials, the processing characteristics of one material (wide-area processing efficiency / localized processing efficiency) tend to be biased depending on the thickness of each material, making it difficult to obtain a product that benefits from the processing characteristics of both materials.

[0008] In the course of further intensive research, the inventors came to the conclusion that with the above-mentioned bonding method, it would be difficult to linearly transmit the flexible movement of the base soft material to the hard material because of the clear interface, or adhesive layer, between the two. They then discovered that by forming the hard and soft layers by changing the porosity between layers of a single polymer foam, rather than by bonding, it would be possible to linearly impart the flexible movement of the soft layer to the hard layer, thereby improving processing efficiency not only in localized areas but also over a wide area. They also found that such a pad substrate would be effective not only for the CARE method but also for mechanical polishing, and thus completed the present invention.

[0009] That is, the present invention is as follows. (1) A polishing pad having a catalyst layer for catalytic surface-based etching polishing (CARE) or abrasive grains for mechanical polishing carried on the surface of the pad substrate, characterized in that the pad substrate is made of a polymer foam integrally molded using the same material, and the area extending to the surface is provided with a hard layer with a relatively low porosity that forms part of the polymer foam.

[0010] (2) The polishing pad according to (1), wherein the hard layer is a high-density layer that is compressed more than the other layers. (3) A polishing pad according to (1), wherein the polymer foam is a foam of a thermosetting resin, and at least the surface of the hard layer is a hardened surface that has undergone more thermal curing than the other parts of the polymer foam other than the hard layer.

[0011] (4) A polishing pad having a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing carried on the surface of a pad substrate, characterized in that the pad substrate is made of a polymer molded body integrally molded using the same thermosetting resin material, and the area extending to the surface is provided with a partially thermoset hard layer that forms part of the polymer molded body.

[0012] (5) A method for manufacturing a polishing pad in which a catalyst layer for CARE or abrasive grains for mechanical polishing are supported on the surface of a pad substrate, the method comprising: forming a polymer foam as at least the surface side portion of the pad substrate; heating and softening the surface of the polymer foam; and simultaneously applying pressure to the surface, thereby forming a hard layer with a relatively low porosity that constitutes part of the polymer foam in the area extending to the surface. (6) A method for manufacturing a polishing pad according to (5), in which the softened surface is pressed with a mold material that is harder than the polymer foam and has a flattened pressing surface, thereby forming the hard layer and transferring the flat surface to the surface.

[0013] (7) A method for manufacturing a polishing pad in which a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing are carried on the surface of a pad substrate, the method comprising: forming a polymer molding using a thermosetting resin material as at least the surface side portion of the pad substrate; heating the surface of the polymer molding to thermally harden it; and thereby forming a thermoset hard layer that constitutes part of the polymer molding in the area extending to the surface. [Effects of the Invention]

[0014] With the catalyst pad of the present invention constructed as described above, there is no clear interface between the hard layer and the relatively soft layer underneath, and the soft layer can linearly impart flexible movement to the hard layer. Therefore, when used for CARE or mechanical polishing, it is possible to efficiently process local areas while conforming to the entire surface of the workpiece, and good processing efficiency can be achieved both over a wide area and in local areas.

[0015] In particular, when the hard layer is a high density layer compressed more than the other layers, a hard layer of stable quality having a predetermined porosity can be efficiently obtained by controlling the compression force. Furthermore, when the polymer foam is a foam of a thermosetting resin and at least the surface of the hard layer is a hardened surface that has undergone more thermal curing than the other parts of the polymer foam other than the hard layer, a hard layer of stable quality and a specified hardness can be efficiently obtained by controlling the heating temperature and time.

[0016] Furthermore, in a pad whose base is made of a polymer molded body integrally formed using the same thermosetting resin material and whose area extending to the surface is provided with a partially thermoset hard layer that forms part of the polymer molded body, there is no clear interface between the hard layer and the relatively soft layer underneath, just like in a pad whose part is provided with a hard layer with a relatively low porosity, and the soft layer can linearly impart flexible movement to the hard layer. Therefore, when used for CARE or mechanical polishing, it is possible to efficiently process local areas while conforming to the entire surface of the workpiece, and good processing efficiency can be achieved both over a wide area and in local areas.

[0017] Furthermore, according to the manufacturing method of the present invention, a polymer foam is molded as at least the surface side portion of the pad substrate, and the surface of the polymer foam is heated to soften it while simultaneously pressurizing the surface, thereby forming a hard layer with a relatively low porosity that constitutes part of the polymer foam in the region extending to the surface. This makes it possible to efficiently manufacture catalyst pads with stable quality that can be processed with good efficiency both over a wide area and in localized areas. In particular, the softened surface is pressed with a mold material that is harder than the polymer foam and has a flattened pressurized surface, thereby forming the hard layer and transferring the flat surface to the surface, thereby efficiently producing a hard layer with a flat surface.

[0018] Furthermore, according to the manufacturing method of the present invention, in which a polymer molding is formed using a thermosetting resin material as at least the surface side portion of the pad substrate, the surface of the polymer molding is heated to thermoset, and a thermoset hard layer that constitutes part of the polymer molding is formed in the area extending to the surface, catalyst pads that can be processed with good efficiency both over a wide area and in localized areas can be manufactured efficiently with stable quality. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing the configuration of a polishing pad according to a representative embodiment of the present invention. [Figure 2] FIG. 10 is an explanatory diagram showing a CARE device using a polishing pad. [Figure 3] FIG. 10 is an explanatory diagram showing the processing using the polishing pad. [Figure 4] 4A to 4C are explanatory views showing the procedure for manufacturing the pad substrate of the polishing pad. [Figure 5] 10 is a graph showing the relationship between the heating temperature and the surface roughness of the pad substrate surface for each applied pressure when producing the pad substrate. [Figure 6] Confocal microscope image of the surface of the prepared pad substrate. [Figure 7] Confocal micrograph of the cross section of the prepared pad substrate. [Figure 8] 4 is a graph showing the relationship between the thickness of the hard layer of the produced pad substrate and the heating temperature. [Figure 9] 3 is a photograph showing the hardness of the surface of the hard layer of the produced pad substrate. [Figure 10] 2 is a graph showing the relationship between the surface roughness of a workpiece and the amount of polishing when the polishing pads of Example 1 and Comparative Example 1 are used. [Figure 11] 10 is a white light interferometer image of the surface of a workpiece after processing using the polishing pad of Example 1. [Figure 12] 1 is a confocal microscope image of the surface of the pad substrate of Example 2. [Figure 13] 1 is a graph showing the relationship between the surface roughness of a workpiece and the amount of polishing when the polishing pads of Example 2 and Comparative Example 2 are used. [Figure 14]10A and 10B are atomic force microscope (AFM) images of the surface of a workpiece before and after processing when the polishing pad of Example 2 is used. [Figure 15] 4 is a cross-sectional profile of a workpiece after being processed with the polishing pad of Example 2. [Figure 16] 10 is a white light interferometer image of the surface of the workpiece when the polishing pad of Example 2 is used. [Figure 17] Graph showing the results of PSD analysis of the surface of the workpiece after being processed with the polishing pad of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0020] Next, the present invention will be described in more detail based on the embodiments shown in the accompanying drawings.

[0021] The polishing pad 1 according to the present invention is a polishing pad used for CARE or mechanical polishing, and has a catalyst layer 11 for CARE or abrasive grains for mechanical polishing carried on the surface of a pad substrate 10. In this embodiment, the pad substrate 10 is particularly characterized in that it is made of a polymer foam 2 molded using the same material, and that a hard layer 22 with a relatively low porosity is provided in a portion of the region extending to the surface.

[0022] Such hard layer 22 is integrally formed from the same material as the relatively soft layer (referred to as the "soft layer") 21 underneath, so the material is continuous and there is no clear interface between the layers, and the soft layer 21 imparts linear flexibility to the hard layer 22. Therefore, whether used in the CARE method or mechanical polishing, the deformation of the soft layer 21 allows the polishing pad 1 to conform to the entire surface of the workpiece, while the hard layer 22 allows localized areas to be processed efficiently with priority given to convex portions, resulting in good processing efficiency in both wide and localized areas.

[0023] 2 shows an example of a CARE apparatus A1 using a polishing pad 1 of the present invention. The polishing apparatus A1 is configured to perform processing while a workpiece 9 and polishing pad 1 are immersed in water 8. The polishing apparatus A1 includes a container 3 for holding the water 8, a polishing pad 1 having a catalyst layer 11 on its surface that serves as a processing reference surface and placed in the container 3 immersed in the water 8, a workpiece holder 4 that holds the workpiece 9 and is immersed in the water 8, and is placed in the container 3 in contact with or very close to the surface (processing reference surface) of the catalyst layer 11 of the polishing pad 1, and a drive mechanism 5 that moves the polishing pad 1 and the workpiece holder 4 relative to each other.

[0024] The workpiece holder 4, which holds a workpiece 9 having an area smaller than that of the polishing pad 1, and the polishing pad 1 are rotated at a predetermined speed on parallel but eccentric rotation axes 50 and 51. The workpiece holder 4 is also designed to adjust the load to adjust the contact pressure of the workpiece 9 against the polishing pad 1. Then, the workpiece 9 is chemically etched and polished by inducing a hydrolysis reaction with the aid of a catalyst.

[0025] According to the polishing pad 1 of the present invention, as shown in the left diagram of Fig. 3, the deformation of the soft layer 21 allows the polishing pad 1 to conform to the entire surface of the workpiece 9, while the hard layer 22 allows localized areas to be processed efficiently with priority given to convex portions, as shown in the right diagram of Fig. 3, thereby achieving good processing efficiency both over a wide area and in a localized area. In this embodiment, the "soft layer" is a layer that elastically deforms under processing pressure, while the "hard layer" is a layer that is harder than the soft layer and hardly deforms under processing pressure due to its low porosity.

[0026] The polymer foam 2 having the hard layer 22 and the soft layer 21 is not a laminate of two or more foams, but is a foam molded as a single unit using the same material, and the hard layer 22 is formed in a region R1 that extends to the surface, which is a part of the foam. Of course, it is possible to laminate another structure, for example, a second polymer foam, to the back side of such a polymer foam 2.

[0027] The hard layer 22 is a layer that has been compressed to have a higher density than the soft layer 21, and the pores are crushed by such compression, resulting in a smaller porosity. There is no problem even if the openings of the pores remain on the surface of the hard layer 22. In fact, if the openings of the pores remain without being crushed by compression, recesses are formed on the surface of the catalyst layer 11 formed thereon, which improve the absorption of water, which is the processing fluid, and serve as pockets that trap impurities, thereby contributing to improved processing efficiency, which is preferable.

[0028] Because the hard layer 22 is integral with the soft layer 21 rather than being bonded thereto, there is no need for an additional adhesive layer, and the thickness can be set to the minimum required. This also contributes to linearly imparting the flexibility of the soft layer 21 to the hard layer 22. The thickness of the hard layer 22 is set within a suitable range depending on the material of the polymer foam 2 and the spatial frequency of the desired processed surface roughness. More specifically, in a hard layer 22 having a relatively low porosity, as in the present embodiment, the hard layer is defined as a region in a cross section of the pad substrate cut in an arbitrary thickness direction, where the ratio of the area of ​​closed pores within the region when expanding in the thickness direction from the surface position is equal to or less than a predetermined ratio within a range of 0 to 15%, which is determined depending on the material of the polymer foam 2 and the spatial frequency of the desired processed surface roughness. The thickness of the hard layer is preferably approximately 50 to 500 μm, and more preferably 50 to 200 μm. If the thickness is greater than 500 μm, even if the area where the void ratio is 15% or less is used as the hard layer, the strength of the hard layer 22 will be too high, hindering the deformation of the soft layer 21 and making it impossible to obtain the benefits of the flexibility of the soft layer 21.

[0029] The thickness of the hard layer 22 can be set by adjusting (e.g., using a thermal diffusion equation) the temperature and time when heating and softening the polymer foam 2, and the pressure and time when simultaneously applying pressure, depending on the material and foaming degree (porosity) of the polymer foam 2. The combined thickness of the hard layer 22 and the soft layer 21 is preferably 1 mm or more, since the pad base must be self-supporting. The ratio of the hard layer 22 to the soft layer 21 is also important, with the ratio (thickness of the hard layer) / (thickness of the soft layer) being preferably 1 / 10 to 1. If the ratio is less than 1 / 10, the processing characteristics of the soft layer 21 will dominate, reducing the processing efficiency in localized areas. Conversely, if the ratio is greater than 1, the processing characteristics of the hard layer 22 will dominate, reducing the processing efficiency in large areas.

[0030] The polymer foam 2 can be made of a wide variety of foams, including elastomers such as polyurethane, polystyrene, polyvinyl chloride, polyethylene, ABS, natural rubber, and silicone. Among these, thermosetting resin foams are preferred for producing a hard layer 22 with high surface hardness. Specifically, epoxy urethane resin foams are more preferred. When such a thermosetting resin foam is used, the hard layer 21 has a low porosity and is a thermoset layer. The cell structure of the polymer foam 2 may be either closed or open cells. However, open-cell foams are easier to form for forming a high-density, compressed hard layer 22, and open cells also provide superior flexibility to the soft layer 21 during processing.

[0031] To fabricate the pad substrate 10 made of such a polymer foam 2, first, the polymer foam 2 is molded as at least the surface side portion of the pad substrate 10, and as shown in Fig. 4, the surface of the polymer foam 2 is heated and softened by a heater 60, and at the same time, the surface is pressed by being sandwiched between a metal plate 61. As a result, a hard layer 22 with a relatively low porosity that constitutes part of the polymer foam 2 is formed in a region R1 extending to the surface.

[0032] In this example, by using a Si substrate with a flat surface as the pressure plate 62 on the heater 60 side and as a mold material, a flat surface is formed on the surface of the hard layer 22, with the flatness of the surface being transferred to the surface of the hard layer 22. The formation of the hard layer 22 is temperature-dependent; in the case of epoxy urethane resin foam, heating to approximately 200°C or higher causes the surface to become fluid, making it possible to transfer the flat surface. The thickness and surface hardness of the hard layer 22 can be appropriately set depending on the material of the polymer foam 2, its foaming degree, heating temperature, heating time, pressure, pressure time, etc.

[0033] The catalytic substance of the catalyst layer 11 supported on the surface of the hard layer 22 is a transition metal, such as Pt, Ru, Ti, Ni, Cr, or Fe, or may be an alloy. These are formed into a film by sputtering on the surface of the hard layer 22. The thickness of the catalyst layer 11 is preferably in the range of 50 to 100 nm.

[0034] In the above embodiment, an example was described in which the surface of the polymer foam 2 was heated to soften it and simultaneously pressurized to form a hard layer with a relatively low porosity. However, other embodiments include cases in which the polymer foam is a thermosetting resin foam and the hard layer is formed by simply heating the surface and thermosetting it without applying pressure. Such a hard layer can be defined as a thermoset layer, and its porosity is the same as that of the soft layer. Furthermore, still another embodiment includes a case in which, similarly in the case of a thermosetting resin, a non-foam polymer molded body is used instead of the polymer foam 2, and the hard layer is formed by simply heating the surface and thermosetting it without applying pressure. In this case, the hard layer can also be defined as a thermoset layer.

[0035] In the case of such a hard layer that is simply thermally cured, the thickness of the hard layer can be set thinner than the hard layer of the representative embodiment with a reduced porosity described above, and a thin hard layer of 0.5 to 3 μm is also preferable. That is, the thickness of the hard layer is preferably approximately 0.5 to 500 μm, and more preferably 0.5 to 200 μm. In addition, the surface roughness is transferred using a Si substrate with a flat surface, and the catalyst substance to be supported is the same as in the representative embodiment described above.

[0036] In the above embodiment, the polishing pad 1 used in the CARE device A1 has been described as an example. However, the configuration of the pad substrate 10 is the same as that of mechanical polishing, except that abrasive grains are carried on the surface instead of a catalyst. Such abrasive grains can be carried on the surface by various known methods, such as gluing or spin coating. It is also possible to carry the abrasive grains on the surface in advance during heating and compression to form the hard layer 22, so that the abrasive grains are carried on the surface simultaneously with the formation of the hard layer 22. However, when used in such mechanical polishing, the above-described transfer of the flat surface is not necessary. [Example]

[0037] Below, we will explain the results of actually preparing a polishing pad and performing CARE using it.

[0038] (Pad substrate preparation, heating temperature and surface roughness) A pad substrate was prepared according to the procedure shown in Figure 4 under the following conditions, and its surface was evaluated. Polymer foam: Epoxy urethane resin foam Mold material: planarized silicon substrate (surface roughness 0.4 nm) Heater temperature: 120℃ / 150℃ / 200℃ / 230℃ / 250℃ / 300℃ Cooking time: 4 minutes Pressure (compression pressure): 0.14MPa / 0.28MPa / 0.42MPa

[0039] Figure 5 is a graph showing the relationship between heating temperature and surface roughness Sq (root mean square height) for each pressure, and Figure 6 shows confocal microscope images and surface roughness Sq of the surface of a pad substrate fabricated under conditions of a pressure of 0.14 MPa and a heating temperature of 120°C / 230°C. As can be seen from Figures 5 and 6, the transfer effect using the Si substrate appears at temperatures above 200°C, and a smooth surface is formed over the entire surface. In the case of epoxy urethane resin foam, heating above 200°C reveals that the surface becomes fluid, resulting in the transfer of a flat surface. It can also be seen that there is little correlation with the pressure.

[0040] (Pad base fabrication, heating time and hard layer thickness) Next, the relationship between the thickness of the hard layer and heating time of pad substrates fabricated by varying only the heating time while maintaining a constant pressure of 0.14 MPa and a constant heating temperature of 200°C was investigated. The thickness of the hard layer was measured based on the confocal microscope photograph of the cross section of the pad substrate after treatment shown in Figure 7, in which the region with a porosity of less than 10% of the untreated porosity was defined as the hard layer.

[0041] Figure 8 is a graph showing the relationship between the thickness of the hard layer of the pad substrate fabricated under the above conditions and the heating temperature. It can be seen that the thickness of the hard layer can be controlled by the heating time. Incidentally, as shown in Figure 7, a hard layer with a thickness of 125 μm was formed after a heating time of 40 minutes. Here, the thickness was calculated assuming that the hard layer had a porosity of 10% or less.

[0042] (Pad substrate fabrication and evaluation of hard layer surface hardness) Figure 9 shows the results of a test to determine the hardness of the hard layer surface of a pad substrate fabricated under the above conditions with a heating time of 40 minutes. The test involved pressing a diamond indenter against the hard layer surface with a force of 5 mN for 30 seconds, and evaluating the size of the indentation formed. As shown in Figure 9, the indentation on the hard layer surface was smaller than that on an untreated one (no hard layer (no pressure, no heating)), indicating that the hard layer was hardened by the heat treatment.

[0043] (Processing experiment 1) Two types of polishing pads were prepared: one in which Ru was supported as a catalyst on the surface of a pad substrate fabricated by the above heating time of 40 minutes (pressure of 0.14 MPa, heating temperature of 200°C) by magnetron sputtering (Example 1), and the other in which Ru was supported as a catalyst on the surface of an untreated pad without forming a hardened layer by magnetron sputtering (Comparative Example 1). Using the apparatus shown in Figure 2, these polishing pads were each mounted, and CARE was performed on a Si substrate under the following conditions. ·Processing fluid: ultrapure water Processing pressure (contact pressure): 60kPa Relative speed: 74mm / s

[0044] Fig. 10 is a graph showing the relationship between the surface roughness Sq and the amount of processing of a workpiece when using the polishing pads of Example 1 and Comparative Example 1, and Fig. 11 shows a white light interferometer image of the surface of the workpiece after processing using the polishing pad of Example 1, as well as the surface precision PV (peak to valley) and surface roughness Sq. It can be seen that by using the polishing pad of Example 1, excessive processing amount is suppressed and highly efficient polishing is possible.

[0045] (Processing experiment 2) Two types of polishing pads were prepared: one in which Ru was supported as a catalyst on the surface of a pad substrate fabricated under the following conditions by magnetron sputtering (Example 2), and the other in which Ru was supported as a catalyst on a conventional fluororubber pad substrate by magnetron sputtering (Comparative Example 2). As shown in Figure 12, a hard layer of approximately 200 μm was formed on the pad substrate of Example 2, and its surface roughness Sq was 0.071 μm. The thickness of the hard layer was calculated assuming a porosity of 10% or less from the surface. Mold material: planarized silicon substrate (surface roughness 0.4 nm) Polymer foam: Epoxy urethane resin foam Heater temperature: 230℃ Cooking time: 4 minutes Pressure (compression pressure): 230 MPa

[0046] Then, using the apparatus of FIG. 2, the polishing pads of Example 2 and Comparative Example 2 were attached, and CARE was performed on a Nd-YAG ceramic plate (φ20 mm) as the workpiece under the following conditions. ·Processing fluid: Ultrapure water pH6.86 Processing pressure (contact pressure): 70kPa Relative velocity: 10cm / s

[0047] (Methods of measurement and evaluation) FIG. 13 is a graph showing the relationship between the surface roughness and the amount of processing of the workpiece when the polishing pads of Example 2 and Comparative Example 2 are used, and FIG. 14 is a graph showing the relationship between the surface roughness and the amount of processing of the workpiece when the polishing pad of Example 2 is used, and FIG. 2 The AFM images and surface roughness Sq of the localized area measured before and after processing ((a) in the figure is the image before processing, and (b) is the image measured at four points A to D at 2.5 mm intervals after processing), and Figure 15 is the cross-sectional profile of the workpiece after processing with the polishing pad of Example 2.

[0048] The results in Figure 13 show that the amount of excess processing can be reduced and polishing can be performed efficiently by using the polishing pad of Example 2. Furthermore, as can be seen from Figures 14 and 15, by using the polishing pad of Example 2, localized processing progressed over almost the entire surface of the workpiece, and the crystal grains on the outermost surface were processed preferentially, thereby suppressing grain boundary steps.

[0049] FIG. 16 shows the surface of the workpiece when the polishing pad of Example 2 was used, with a size of 700×930 μm. 2 FIG. 17 is a graph showing the results of a PSD analysis (periodicity analysis using power spectral density (PSD)) of the workpiece surface after processing with the polishing pad of Example 2. The results of the PSD analysis show that surface roughness is improved in the low-frequency region (long-wavelength region). These results show that using the polishing pad of Example 2 reduces surface roughness even over a wide area. [Explanation of symbols]

[0050] 1 polishing pad 2. Polymer foam 3 containers 4 Workpiece holder 5 Drive mechanism 8 water 9 Workpiece 10 Pad base 11 Catalyst layer 21 Soft layer 22 Hard layer 50, 51 Rotation axis 60 Heater 61 Metal Plate 62 Pressure plate A1 CARE device R1 area

Claims

1. A polishing pad having a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing carried on the surface of a pad substrate, A polishing pad characterized in that the pad substrate is made of a polymer foam integrally molded using the same material, and in the area extending to the surface, it has a hard layer with a relatively low porosity that forms part of the polymer foam.

2. 2. The polishing pad of claim 1, wherein the hard layer is a high density layer that is compressed relative to the other layers.

3. the polymer foam is a foam of a thermosetting resin, 2. The polishing pad according to claim 1, wherein at least the surface of said hard layer is a hardened surface that has been thermally cured more than the other portions of said polymer foam than the hard layer.

4. A polishing pad having a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing carried on the surface of a pad substrate, A polishing pad characterized in that the pad base is made of a polymer molded body integrally molded using the same thermosetting resin material, and the area extending to the surface is provided with a partially thermoset hard layer that forms part of the polymer molded body.

5. A method for manufacturing a polishing pad in which a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing is carried on the surface of a pad substrate, comprising: a polymer foam is molded as at least a surface side portion of the pad substrate; A method for manufacturing a polishing pad, characterized in that the surface of the polymer foam is heated to soften it and at the same time the surface is pressurized, thereby forming a hard layer with a relatively low porosity that constitutes part of the polymer foam in the area extending to the surface.

6. 6. A method for manufacturing a polishing pad according to claim 5, wherein the softened surface is pressed with a mold material that is harder than the polymer foam and has a flattened pressing surface, thereby forming the hard layer and transferring the flat surface to the surface.

7. A method for manufacturing a polishing pad in which a catalyst layer for catalyst surface-based etching polishing or abrasive grains for mechanical polishing is carried on the surface of a pad substrate, comprising: a polymer molded body is formed using a thermosetting resin material as at least a surface side portion of the pad substrate; A method for manufacturing a polishing pad, comprising heating the surface of the polymer molding to thermally harden it, thereby forming a thermally hardened hard layer that constitutes part of the polymer molding in the area extending to the surface.

Images