Polishing pad and method of manufacturing the same

Abstract

To cause an abrasive pad with semi-fixed abrasive particles to exhibit higher polishing efficiency while using diamond particles as the abrasive particles, in a wafer polishing process.SOLUTION: An abrasive pad comprises a base material 20 which comprises a resin and in which a plurality of pores are formed, and abrasive particles 30 held in the base material 20 or in the pores, and constitutes a polishing surface 40a for polishing a work-piece. The pores include a plurality of independent pores 20a, and the abrasive particles 30 include diamond particles 30a held in the independent pores 20a, and alumina particles 30b held in the base material 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Documents 1 to 3 disclose conventional polishing pads. These polishing pads have a base material and abrasive particles. The base material is binder It is made of resin and has a plurality of pores formed therein. binder Resins include polyvinylidene fluoride, epoxy resin, and PES (polyether Sulfo The abrasive particles are made of silica or the like and are held within the matrix or pores.

[0003] These polishing pads are manufactured through a mixing process, a molding process, and a pore-forming process. In the mixing process, a paste containing a resin solution in which a binder resin is dissolved in a solvent, abrasive particles, and a pore-forming agent is obtained. In the molding process, a sheet-like molded body is obtained from the paste. In the pore-forming process, the molded body undergoes a phase separation process, hardening the binder resin and forming pores. The front and / or back surfaces of the intermediate body obtained in the pore-forming process are ground to form a polishing surface for polishing the object to be polished.

[0004] The polishing pad obtained in this way is a semi-fixed abrasive pad, and is used for polishing processing using the CMP (Chemical Mechanical Polishing) method, using a polishing liquid that does not contain abrasive particles or simply water as the polishing liquid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-49256 [Patent Document 2] Patent Publication No. 2021-61306 [Patent Document 3] Patent No. 6243009 Summary of the Invention [Problem to be solved by the invention]

[0006] When polishing a SiC wafer using the CMP method, for example, a rough lapping process is generally performed to adjust the thickness, followed by a finish lapping process. In these polishing processes, it is efficient to use diamond particles, which are harder than other particles, as abrasive particles.

[0007] However, according to the results of tests conducted by the inventors, the above-mentioned conventional polishing pads do not provide sufficient polishing efficiency when polishing SiC wafers.

[0008] The present invention was made in consideration of the above-mentioned conventional situation, and aims to solve the problem of achieving higher polishing efficiency in wafer polishing processing while using diamond particles as abrasive particles in a semi-fixed abrasive particle polishing pad. [Means for solving the problem]

[0009] The polishing pad of the present invention comprises a base material made of a binder resin and having a plurality of pores formed therein, and abrasive particles held in the base material and the pores, and the pad constitutes a polishing surface for polishing an object to be polished, and the binder resin is polyethersulfone, The pores, including pores, interconnected pores, and closed pores, account for 64.1 to 72.5% by volume, The continuous pores are interconnected with each other or with the pores of 1 μm or larger, The isolated pores are connected to the pores smaller than 1 μm but are not connected to the pores equal to or larger than 1 μm, The abrasive particles are arranged in the closed pores having a length of 10 μm or less at the longest part of the inner diameter. Most The diamond particles having an average particle size of 1 to 10 μm are held in the base material. Most The alumina particles are held in the glass and have an average particle size of 0.1 to 5 μm. fruit, The diamond particles are contained in an amount of 7.1 to 10.1% by volume, and the alumina particles are contained in an amount of 2.7 to 3.5% by volume. It is characterized by the

[0010] The inventors have conducted extensive research into why sufficient polishing efficiency cannot be achieved in wafer polishing even when diamond particles are held in the pores of the base material of a semi-fixed abrasive pad, and have concluded that many diamond particles fall off from the base material during polishing, resulting in a shortage of diamond particles that actually contribute to the polishing process.

[0011] Therefore, we aimed to improve the retention of diamond particles in the base material during polishing. We thought that the pore structure of the base material was important for this purpose, and came up with the idea of ​​forming independent pores in the base material and holding the diamond particles within the independent pores. When we conducted a test of polishing a wafer using the polishing pad obtained in this way, we demonstrated that sufficient polishing efficiency could be obtained.

[0012] Furthermore, according to the results of the inventors' tests, simply forming a plurality of independent pores in the base material and holding diamond particles within the independent pores makes it difficult for the base material to expose the diamond particles during processing, and further improvement in polishing efficiency is desired. Based on these findings, the present invention was completed.

[0013] The polishing pad of the present invention contains diamond particles, which are harder than other particles, as abrasive particles. In addition, the base material has independent pores, and the diamond particles are held within the independent pores. The term "independent pores" refers to pores that exist independently within the base material or that are not connected to pores of a certain diameter or larger. The term "interconnected pores" is used in contrast to the independent pores, but the term "interconnected pores" refers to pores that are connected to each other or to pores of a certain diameter or larger. Pores are inevitably generated when replacing the solvent in the molded body during the production of the polishing pad. In the present invention, the inventors have confirmed that the independent pores refer to pores that are not connected to pores of 1 μm or larger. The pores in the above-mentioned conventional polishing pads are interconnected pores or interconnected pores of 1 μm or larger, which are different from the independent pores in the polishing pad of the present invention.

[0014] According to the test results of the inventors, the polishing pad of the present invention can improve the polishing efficiency when polishing, for example, SiC wafer as the object to be polished.This is thought to be because the retention of diamond particles in the base material during polishing improves, and the diamond particles that can actually contribute to polishing can be sufficiently secured.It is presumed that the reason for the improved retention of diamond particles is that, since the isolated pores are generated by nucleation growth type phase separation, the concentration gradient is steeper than that of the interconnected pores, and the side walls are thicker than the side walls of the interconnected pores, so that the diamond particles are easily held in the isolated pores.

[0015] Furthermore, the polishing pad of the present invention contains alumina particles in which the abrasive particles are held in a matrix. According to the inventors' test results, the inclusion of alumina particles in the matrix reduces the matrix's toughness. This improves the matrix's retraction resistance during processing, making it easier for damaged diamond particles to be exposed and removed at the appropriate time, allowing for early start of polishing with new diamond particles.

[0016] Therefore, the polishing pad of the present invention can achieve higher polishing efficiency in wafer polishing while using diamond particles as abrasive particles in a semi-fixed abrasive particle type polishing pad.

[0017] The method for producing a polishing pad of the present invention comprises: A method for manufacturing the polishing pad, a mixing step for obtaining a paste containing a resin solution in which a binder resin is dissolved in a solvent, diamond particles, alumina particles, a pore-forming agent, and an additive, so that a nucleation-growth type phase separation process occurs; a molding step of obtaining a sheet-shaped molded body from the paste; a pore forming step of subjecting the molded body to the phase separation step, curing the binder resin, and forming the independent pores, The paste contains 16 to 17 parts by mass of polyethersulfone as the binder resin, 19 to 27 parts by mass of the diamond particles, 8 to 14 parts by mass of the alumina particles, 29 to 32 parts by mass of N-methyl-2-pyrrolidone as the solvent, 16 to 18 parts by mass of granulated sugar powder as the pore-forming agent, and 2 to 3 parts by mass of glycerin as the additive, and has a viscosity at 40°C of 578.6 to 1102.0 Pa·s.

[0018] During the mixing process, the volume ratios of the binder resin, solvent, and abrasive particles are appropriately adjusted so that a nucleation-growth phase separation process occurs during the pore formation process. This allows the nucleation-growth phase separation process to occur during the pore formation process. When nucleation-growth phase separation occurs, unlike the spinodal decomposition phase separation process, numerous spherical, isolated solvent-rich phases are dispersed within the resin-rich phase. These solvent-rich phases are irregular in size and relative position, and the concentration gradient at the interface between the solvent-rich phase and the resin-rich phase is steep. After the solvent is removed and the binder resin is cured, multiple independent pores of irregular size and irregularly dispersed can be formed in the base material. The solvent in the independent pores is expelled from the pores and, in some cases, through interconnected pores to the outside of the base material. In the base material obtained in this manner, the abrasive particles are retained within the base material or within the pores.

[0019] According to the results of tests conducted by the inventors, by using such a paste, the pore structure of the base material can be made to have a closed pore structure having a plurality of closed pores of an appropriate size.

[0020] Furthermore, the abrasive particles, namely, diamond particles, alumina particles, and silica particles, have different wettability with the resin solution, with diamond particles and silica particles being more likely to be held within the closed pores, and alumina particles being more likely to be held within the matrix. [Effects of the Invention]

[0021] According to the present invention, in the polishing process of a wafer, a high polishing efficiency can be achieved while using diamond particles as abrasive particles in a semi-fixed abrasive particle type polishing pad. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is an enlarged cross-sectional view schematically showing an intermediate product of the polishing pads of Examples 1 to 4 after a pore forming step. [Figure 2] FIG. 2 is an enlarged cross-sectional view schematically showing the polishing pads of Examples 1 to 4 after the cutting step. [Figure 3] FIG. 3 is an SEM photograph of the polishing pad of Example 1, taken at 50,000 times magnification, of a cross section parallel to the polishing surface. [Figure 4] FIG. 4 is an SEM photograph of the polishing pad of Example 1, taken at 100,000 times magnification, of a cross section parallel to the polishing surface. [Figure 5] FIG. 5 is an SEM photograph of the polishing pad of Example 2, taken at 50,000 times magnification, of a cross section parallel to the polishing surface. [Figure 6] FIG. 6 is a 1000x SEM photograph of the cross section of the polishing pad of Example 3, parallel to the polishing surface. [Figure 7] FIG. 7 is a 1000x SEM photograph of the cross section parallel to the polishing surface of the polishing pad of Example 4. [Figure 8] FIG. 8 is an SEM photograph of the polishing pad of Comparative Example 1, taken at 1000 magnifications, of a cross section parallel to the polishing surface. [Figure 9] FIG. 9 is an SEM photograph of the polishing pad of Comparative Example 2, taken at 1000 magnifications, of a cross section parallel to the polishing surface. [Figure 10] FIG. 10 is an SEM photograph of the polishing pad of Comparative Example 3, taken at 1000 magnifications, of a cross section parallel to the polishing surface. [Figure 11] FIG. 11 is an SEM photograph of the polishing pad of Comparative Example 4, taken at 1000 magnifications, of a cross section parallel to the polishing surface. DETAILED DESCRIPTION OF THE INVENTION

[0023] The length of the longest part of the inner diameter of the closed pores is preferably 10 μm or less, and the average particle size of the diamond particles is preferably 1 to 10 μm. Since the diamond particles are contained within the closed pores and act, it is preferable that the diamond particles be equal to or smaller than the particle size of the longest part of the inner diameter of the closed pores. Furthermore, if the average particle size of the diamond particles is 1 μm or more, the number of diamond particles contained inside can be limited, and the diamond particles act on the wafer as individual particles, resulting in a good surface condition of the wafer after processing.

[0024] The pore diameter of the isolated pores can be measured by binarizing an SEM photograph of a cross section parallel to the polished surface using an image analyzer, and recognizing, for example, a black area surrounded by connected white areas in the binarized image as a single particle.

[0025] Constitute the base material binder The resin is polyethersulfone (PES )of It is possible to adopt 。

[0026] The diamond particles may be any of single crystal diamond, polycrystalline diamond, and pseudo-polycrystalline diamond.

[0027] Since it is preferable that the alumina particles do not block the closed pores, the alumina particles are preferably 5 μm or less, which is half of the 10 μm at the longest point of the inner diameter of the closed pores. Furthermore, if the alumina particles are less than 0.1 μm, the specific surface area is high, making it difficult to stir the paste during production, and the viscosity of the paste increases, making molding difficult. Therefore, it is preferable that the alumina particles have an average particle size of 0.1 to 5 μm.

[0028] The polishing pad of the present invention may contain abrasive particles other than diamond particles and alumina particles. Examples of other abrasive particles include silica particles, ceria particles, zirconia particles, titania particles, manganese oxide particles, barium carbonate particles, chromium oxide particles, and iron oxide particles. These may be used alone or in combination of two or more.

[0029] According to the inventors' tests, it is preferable that the abrasive particles contain silica particles in addition to diamond particles and alumina particles. In this case, the silica particles are held in the closed pores together with the diamond particles, and the silica particles, which are softer than the diamond particles, act as a buffer to press the diamond particles against the wafer appropriately, and the silica particles act as a lubricant between the diamond particles. This is expected to prevent scratches on the wafer caused by the diamond particles. In addition, the silica particles increase the viscosity of the paste, making it easier to form closed pores.

[0030] Since it is preferable that the silica particles do not block the closed pores, the silica particles are preferably 5 μm or less, which is half of the 10 μm at the longest point of the inner diameter of the closed pores. Furthermore, if the silica particles are less than 0.1 μm, the specific surface area is high, making it difficult to stir the paste during production, and the viscosity of the paste increases, making molding difficult. Therefore, it is preferable that the silica particles also have an average particle size of 0.1 to 5 μm.

[0031] According to the results of the inventors' tests, the polishing pad of the present invention preferably contains 7.1% by volume or more of diamond particles, 2.7% by volume or more and 3.5% by volume or less of alumina particles, and 1.4% by volume or more of silica particles. In this case, sufficient polishing efficiency can be obtained in polishing SiC wafers, and a polishing pad that can suppress scratches caused by diamond particles can be easily manufactured.

[0032] The volume ratio of each component in the polishing pad of the present invention is as follows, when the entire polishing pad is taken as 100 volume %: binder resin: 15.4~20.6 Abrasive particles containing diamond particles and alumina particles, vol. %: 11.3~15.3 Volume % Porosity: 64.1~72.5 It is preferably expressed as a volume percent.

[0033] As a solvent, the base material binderAny solvent that can dissolve resins may be used, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0034] The pore-forming agent is added to adjust the pore structure formed in the base material. When an oil-based solvent is used, a water-soluble pore-forming agent can be used. Examples of water-soluble pore-forming agents that can be used include powdered sugar (granulated sugar ground into powder) and cornstarch.

[0035] Additives may be added to the paste as needed. binder Examples include glycerin for adjusting the solubility of the resin.

[0036] The molding process is not particularly limited, and the molding is performed by using a molding device such as a T-die to mold the sheet into a molded product. The molding method is not limited to this as long as it can make the thickness uniform to a certain extent.

[0037] In the pore formation process, for example, the compact is immersed in a water tank with the water temperature adjusted to 10°C or less for a predetermined time to induce a nucleation-and-growth type phase separation process. This results in numerous isolated, spherical, and irregularly sized and positioned solvent-rich phases dispersed in the resin-rich phase. During this process, the solvent in the solvent-rich phase is replaced by water due to the difference in specific gravity.

[0038] In this pore-forming process, when an oil-based solvent is used, an aqueous liquid such as tap water can be used as the replacement liquid. Immersing the molded body in this replacement liquid disperses the solvent-rich phase in the resin-rich phase through a nucleation-growth phase separation process, and simultaneously replaces the solvent in the solvent-rich phase with the replacement liquid, thereby removing the solvent from the molded body. During this process, each isolated solvent-rich phase communicates with the outside of the molded body through pores formed in the resin-rich phase, and the solvent is replaced with the replacement liquid through the pores. When the solvent is removed from the molded body in this way, the resin-rich phase shrinks and hardens, forming minute interconnected pores within the resin-rich phase. Furthermore, using an aqueous liquid such as tap water as the replacement liquid and immersing the molded body in this replacement liquid can simultaneously remove the water-soluble pore-forming agent.

[0039] The molded body from which the solvent and pore-forming agent have been removed is subjected to a drying process to produce an intermediate body, and the front and / or back surfaces of the intermediate body are cut to form a polishing surface, thereby producing the polishing pad of the present invention.

[0040] <Preparation process> The following binder resin, abrasive particles, solvent, pore former and additives were prepared.

[0041] (binder resin) PES (Polyethersulfone) (abrasive particles) Diamond particles (average particle size: 5 μm) Alumina (Al2O3) particles (average particle size: 0.3 μm) Silica (SiO2) particles (average particle size: 0.2 μm) (solvent) N-Methyl-2-pyrrolidone (pore-forming agent) Granulated sugar powdered sugar (additives) glycerin

[0042] <Mixing process> The binder resin, abrasive particles, solvent, pore-forming agent, and additive components were mixed in the proportions (parts by mass) shown in Table 1 to obtain a paste. The volume ratio of the binder resin and solvent was appropriately adjusted so that a nucleation-growth-type phase separation process would occur during the pore formation process. The viscosity (Pa·s) of the obtained paste at 40°C was measured using a parallel-plate oscillatory rheometer in accordance with JIS K 7244-10. The results are also shown in Table 1. The volume ratio of the binder resin and solvent in the obtained paste was appropriately adjusted so that a nucleation-growth-type phase separation process would occur during the pore formation process.

[0043] [Table 1]

[0044] <Forming process> Each of the obtained pastes was used to obtain a sheet-shaped molded body using a T-die.

[0045] <Pore formation process, drying process> The compact was immersed for a predetermined period of time in tap water stored in a water tank and adjusted to a temperature of 10°C or less. This caused a nucleation-growth type phase separation process to occur in the compact, dispersing numerous isolated spherical solvent-rich phases in the resin-rich phase, and replacing the solvent in the compact with tap water to remove the solvent and pore-forming agent from the compact.

[0046] The obtained intermediate 10 was left in the air at room temperature for about two days to remove moisture from the intermediate 10. A schematic cross-sectional view of the intermediate 10 of Examples 1 to 4 is shown in FIG.

[0047] Each intermediate body 10 has a base material 20 and abrasive particles 30. The base material 20 is binderIt is made of resin and has a plurality of independent pores 20a, a plurality of interconnected pores (not shown), and pores (not shown). The independent pores 20a are pores that communicate with pores smaller than 1 μm but do not communicate with pores of 1 μm or larger. The interconnected pores are pores that communicate with each other or with pores of 1 μm or larger. The pores are pores other than the independent pores 20a and interconnected pores.

[0048] The surface of each intermediate body 10 is ground to form a polishing surface 40a for polishing an object to be polished, as shown in FIG. 2. In this way, a polishing pad 40 is obtained. Each polishing pad 40 is also binder The pad 40 comprises a base material 20 made of resin and having a plurality of pores 20a formed therein, and abrasive particles 30 held within the base material 20 or within pores including the closed pores 20a. The abrasive particles 30 consist of diamond particles 30a, alumina particles 30b, and silica particles 30c. The diamond particles 30a and silica particles 30c are held in the base material 20 and in the interconnected pores, but most are held within the closed pores 20a. Most of the alumina particles 30b are held within the base material 20. Each polishing pad 40 is disc-shaped, 300 mm in diameter and 2 mm thick.

[0049] For each polishing pad, the volume ratio (vol%) of each component and density (g / cm 3 The results are shown in Table 2.

[0050] [Table 2]

[0051] 3 to 7 show SEM photographs of a cross section parallel to the polishing surface 40a of each polishing pad 40. As is clear from Figures 3 to 5, the polishing pads 40 of Examples 1 to 4 have a closed pore structure, with diamond particles 30a and silica particles 30c as abrasive particles 30 held in the numerous closed pores 20a, and alumina particles 30b held in the base material 20.

[0052] On the other hand, Fig. 8As shown in Fig. 1, the polishing pad 40 of Comparative Example 1 does not have a closed pore structure, that is, the base material does not have closed pores, but only has interconnected pores and fine pores. 9 As shown in FIG. 1, in the polishing pad 40 of Comparative Example 2, although a closed pore structure is formed, it is clear that the structure is one in which closed pores having a pore diameter of 10 μm or more account for approximately 20%.

[0053] For each of the polishing pads 40 of Examples 1 to 4 and Comparative Examples 1 to 4, a SiC wafer was polished using a wafer polishing test device under the following processing test conditions, and the polishing efficiency (processing rate) (μm / min) and the surface condition of the wafer after processing were examined. The surface condition of the wafer after processing was evaluated by surface roughness Sa (nm) and maximum depth Sz (nm).

[0054] <Test conditions> Testing machine: Wafer polishing machine (Engis EJW-380) Workpiece (object to be polished): SiC wafer (4 inches) Polishing liquid: water Polishing fluid volume: 10 ml / min Processing pressure: 20kPa Platen / Workpiece Rotation Speed: 60 / 60 rpm

[0055] The results are shown in Table 3. As is clear from Table 3, the polishing pads 40 of Examples 1 to 4 all had improved processing rates compared to the polishing pad 40 of Comparative Example 1. Furthermore, the polishing pad 40 of Comparative Example 2 had a high surface roughness Sa and an excessively large maximum depth Sz.

[0056] [Table 3]

[0057] This is thought to be because, in the polishing pads 40 of Examples 1 to 4, the diamond particles 30a and silica particles 30c are well held within the closed pores 20a, improving the retention of the diamond particles 30a on the base material 20 during polishing, and as a result, sufficient diamond particles 30a that actually contribute to polishing can be secured. Also, in the polishing pads 40 of Examples 1 to 4, the abrasive particles 30 contain alumina particles 30b held in the base material 20, which reduces the toughness of the base material 20 and improves the tendency of the base material 20 to recede during processing. In this case, it is thought that the damaged diamond particles 30a are easily exposed and removed at the appropriate time, allowing polishing with new diamond particles 30a to begin early.

[0058] The reason why the processing rate of the polishing pad of Comparative Example 2 was improved compared to that of the polishing pad of Comparative Example 1 is thought to be because the formation of an independent pore structure allows the diamond particles 30a to remain. On the other hand, since a large number of diamond particles 30a are contained in the independent pores 20a with a pore diameter of 10 μm or more, a large number of diamond particles 30a act on the workpiece simultaneously during processing, resulting in a rough surface condition of the workpiece after processing.

[0059] The present invention has been described above in accordance with Examples 1 to 4, but it goes without saying that the present invention is not limited to the above Examples 1 to 4 and can be modified and applied as appropriate within the scope of the invention. [Industrial Applicability]

[0060] The present invention can be used in semiconductor device manufacturing equipment. [Explanation of symbols]

[0061] 20a...Independent pores 20...Base material 30...abrasive particles 30a...Diamond particles 30b...Alumina particles 30c...Silica particles 40a…Polished surface 40...Polishing pad

Claims

1. A polishing pad having a base material made of a binder resin and having a plurality of pores formed therein, and abrasive particles held in the base material and the pores, and constituting a polishing surface for polishing an object to be polished, the binder resin is polyethersulfone, The pores, including pores, interconnected pores, and closed pores, account for 64.1 to 72.5% by volume, The continuous pores are interconnected with each other or with the pores of 1 μm or larger, the isolated pores communicate with the pores smaller than 1 μm but do not communicate with the pores equal to or larger than 1 μm; the abrasive particles include diamond particles having an average particle size of 1 to 10 μm, most of which are held in the closed pores having a length of 10 μm or less at the longest point of the inner diameter, and alumina particles having an average particle size of 0.1 to 5 μm, most of which are held in the matrix; A polishing pad comprising 7.1 to 10.1 volume % of said diamond particles and 2.7 to 3.5 volume % of said alumina particles.

2. A polishing pad as described in claim 1, wherein the diamond particles have an average particle size of 5 μm and the alumina particles have an average particle size of 0.3 μm.

3. the abrasive particles are mostly held within the closed pores, the length of the longest part of the inner diameter of which is 10 μm or less, and contain silica particles with an average particle size of 0.1 to 5 μm; 3. The polishing pad according to claim 1, wherein the silica particles are contained in an amount of 1.4 to 1.8% by volume.

4. The polishing pad according to claim 3, wherein the silica particles have an average particle size of 0.2 μm.

5. A method for manufacturing a polishing pad according to claim 1 or 2, comprising: a mixing step for obtaining a paste containing a resin solution in which a binder resin is dissolved in a solvent, diamond particles, alumina particles, a pore-forming agent, and an additive, so that a nucleation-growth type phase separation process occurs; a molding step of obtaining a sheet-shaped molded body from the paste; a pore forming step of subjecting the molded body to the phase separation step, curing the binder resin, and forming the independent pores, The paste contains 16 to 17 parts by mass of polyethersulfone as the binder resin, 19 to 27 parts by mass of the diamond particles, 8 to 14 parts by mass of the alumina particles, 29 to 32 parts by mass of N-methyl-2-pyrrolidone as the solvent, 16 to 18 parts by mass of powdered granulated sugar as the pore-forming agent, and 2 to 3 parts by mass of glycerin as the additive, and has a viscosity at 40°C of 578.6 to 1102.0 Pa·s.

6. A method for manufacturing a polishing pad according to claim 3 or 4, comprising:

6. The method for manufacturing a polishing pad according to claim 5, wherein the paste contains 2 to 3 parts by mass of silica particles.

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