Polishing pad and method for manufacturing the same

Abstract

To provide a polishing pad which can maintain a stable polishing rate by having appropriate collapsibility, when polishing an object to be polished, and enables provision of an object to be polished having low surface roughness, and a method for manufacturing the same.SOLUTION: A polishing pad includes a base material, and a polishing part arranged on the base material, wherein the polishing part contains a resin and composite fine particles, the composite fine particles contain diamond abrasive grains, and collapse strength of the composite fine particles is 100.0 to 300.0 MPa.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Glass is used as a material for magnetic disks such as hard disk drives, glass substrates used as the base material for reflective masks used in EUV lithography, and LCD substrates and cover glasses for mobile devices such as smartphones and tablets.The surfaces of various glass materials must be highly smooth and have as few micro-defects as possible.Fixed abrasive polishing pads are generally used for surface processing of such glass and difficult-to-cut materials.

[0003] Generally, when increasing the polishing rate to improve processing efficiency, the flatness accuracy of the finished surface tends to decrease, and there is a trade-off between the polishing rate and the flatness accuracy. For this reason, it is difficult to achieve both the polishing rate and the flatness accuracy. For example, in a polishing pad with fixed diamond abrasive grains, the smaller the particle size of the diamond abrasive grains, the lower the surface roughness can be, but the processing speed will be slower.

[0004] For example, Patent Document 1 proposes a grinding tool that uses abrasive grains and dispersed grains that are softer than the abrasive grains in combination to achieve both a high polishing rate and high flattening accuracy, and that bonds the abrasive grains and dispersed grains in a dispersed state within a binder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-092697 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the grinding tool described in Patent Document 1 uses dispersed particles that are softer than the grinding abrasive grains, which means that particles of different strengths are unevenly distributed across the grinding tool surface. This causes variations in the way the surface is ground during the dressing process, which is performed to finish the surface or remove clogging, and deteriorates the polishing characteristics. Therefore, there is still room for improvement in order to maintain the polishing rate and flattening accuracy even after dressing.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a polishing pad and a manufacturing method thereof that can maintain a stable polishing rate and produce polished objects with low surface roughness. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by using composite fine particles having a predetermined crushing strength, and have thus completed the present invention.

[0009] That is, the present invention is as follows. [1] A substrate and an abrasive portion disposed on the substrate, the polishing portion includes a resin and composite fine particles, The composite microparticles include diamond abrasive grains, The crushing strength (Cs) of the composite microparticles is 100.0 to 300.0 MPa. Polishing pad. [2] The value (SD / Cs) obtained by dividing the standard deviation (SD) of the crushing strength of the composite microparticles by the crushing strength (Cs) is 15.0 to 70.0%. [1] The polishing pad according to [1]. [3] The standard deviation (SD) of the crushing strength of the composite microparticles is 15.0 to 170.0 MPa. [1] or [2]. The polishing pad according to [1] or [2]. [4] The polishing portion has a convex portion. The polishing pad according to any one of [1] to [3]. [5] a firing step of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles; a curing step of curing a curable composition containing a resin and the composite fine particles to obtain a polishing part; a joining step of joining a surface of the polishing part opposite to the polishing surface to a substrate, The crushing strength of the composite microparticles is 100.0 to 300.0 MPa. A method for manufacturing a polishing pad. [6] [1] to [4], comprising a step of polishing an object to be polished using the polishing pad according to any one of [1] to [4]. Manufacturing method for polished products. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a polishing pad and a manufacturing method thereof that can maintain a stable polishing rate and can produce a polished object with low surface roughness. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a polishing pad according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the polishing pad of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0013] 1. Polishing pad The polishing pad of this embodiment comprises a substrate and a polishing portion disposed on the substrate, the polishing portion containing a resin and composite microparticles, the composite microparticles containing diamond abrasive grains, and the crushing strength of the composite microparticles is 100.0 to 300.0 MPa.

[0014] A schematic perspective view of a polishing pad according to this embodiment is shown in Figure 1. As shown in Figure 1, this polishing pad 10 includes a substrate 11 and a polishing portion 12 disposed on the substrate 11. In Figure 1, a plurality of convex portions formed by the polishing portion 12 are disposed on the surface of the substrate 11, forming an uneven pattern.

[0015] The polishing portions 12 may form a concave-convex pattern together with the substrate 11 as shown in Fig. 1, or may be a uniform layer formed on the surface of the substrate. The concave-convex pattern may be a pattern (negative pattern) formed by the polishing portions 12 formed by punching out dots from a uniform layer, in addition to a concave-convex pattern formed by arranging convex portions, or any other pattern.

[0016] FIG. 2 is a schematic cross-sectional view of a polishing pad according to this embodiment. As shown in FIG. 2, the polishing portion 12 of the polishing pad 10 according to this embodiment contains composite microparticles 14 and a resin 15. By including composite microparticles 14 with a predetermined crushing strength, the polishing portion 12 can prevent the diamond abrasive grains contained in the composite microparticles 14 from easily detaching from the composite microparticles 14, thereby preventing a decrease in the polishing rate and scratches caused by the rolling of the released diamond abrasive grains. Furthermore, since the composite microparticles 14 have a predetermined crushing strength, scratches caused by the diamond abrasive grains being firmly fixed are prevented. Furthermore, as polishing progresses, the polishing surface of the polishing portion 12 is gradually worn away, forming a new polishing surface where the composite microparticles 14 embedded in the polishing portion 12 are exposed, which tends to maintain the polishing rate.

[0017] Each component of the polishing pad of this embodiment will be described in detail below.

[0018] 1.1. Base material The substrate is a member on which the polishing portion is formed, and may be attached to the polishing device via an adhesive layer or the like, which will be described later.

[0019] The substrate is not particularly limited, but examples thereof include polyester sheets such as polyethylene terephthalate sheets, polypropylene terephthalate sheets, and polybutylene terephthalate sheets; polyolefin sheets such as polyethylene (PE) sheets, polypropylene (PP) sheets, and ethylene-propylene copolymer sheets; polyether ether ketone (PEEK) sheets, polyphenylene sulfide (PPS) sheets, polycarbonate sheets, and acrylic sheets. Among these, polyester sheets are preferred from the viewpoints of chemical resistance, heat resistance, and economy, while acrylic sheets are preferred from the viewpoints of rigidity, adhesiveness, and processability.

[0020] 1.2. Polishing section The abrasive part contains a resin and composite particles, and may contain other spacer particles as needed. The abrasive part may be formed as a uniform layer on the surface of the substrate, or may be formed alone or together with the substrate to form a concave-convex pattern (see Figures 1 and 2). When the abrasive part rubs the surface of the workpiece, the abrasive particles held by the composite particles scrape the surface of the workpiece, and the composite particles gradually break down, supplying new abrasive particles.

[0021] Among these, from the viewpoint of supplying or discharging liquid components used during polishing, such as coolant, to the polishing surface and efficiently discharging polishing debris, it is preferable that the polishing part has an uneven pattern, and more preferably a regular uneven pattern. Having a regular pattern enables uniform polishing and polishing with excellent surface quality can be achieved. Note that a "regular pattern" refers to a pattern obtained by arranging multiple small unit patterns. The surface of the polishing part opposite the substrate serves as the polishing surface for polishing the workpiece.

[0022] The concave-convex pattern is not particularly limited as long as it has portions that contact the workpiece (convex portions) and portions that do not contact the workpiece (concave portions). Examples include a positive pattern (a pattern with dot-shaped convex portions) in which the abrasive portions 12 are independently formed on the substrate 11 as shown in FIG. 1; a negative pattern (a pattern with dot-shaped concave portions) in which the abrasive portions are continuously formed on the substrate; a pattern with donut-shaped convex portions; a pattern with approximately C-shaped convex portions; a pattern with concentric circular portions that contact the workpiece and portions that do not contact the workpiece; a grid-shaped pattern with portions that contact the workpiece and portions that do not contact the workpiece; a radial pattern with portions that contact the workpiece and portions that do not contact the workpiece; a spiral pattern with portions that contact the workpiece and portions that do not contact the workpiece; or a pattern formed by combining these. Among these, a pattern with dot-shaped convex portions is preferred. Having such a concave-convex pattern tends to further improve the discharge of polishing debris.

[0023] In addition, the three-dimensional shape of the dots in a pattern having dot-shaped protrusions is not particularly limited, and examples thereof include hemispheres, approximately hemispheres, spherical caps, approximately spherical caps, spherical bands, approximately spherical bands, semi-ellipsoids, approximately semi-ellipsoids, cylinders (cylindrical, approximately cylindrical, elliptical, approximately elliptical, polygonal), and truncated cones (circular truncated cones, approximately circular truncated cones, elliptical truncated cones, approximately elliptical truncated cones, polygonal truncated cones). Of the above, the truncated cones may be truncated cones that expand from the substrate side toward the polishing surface side, or from the polishing surface side toward the substrate side. Furthermore, in a pattern having dot-shaped recesses, the three-dimensional shape of the space in the recesses may be similar to the three-dimensional shape in a pattern having dot-shaped protrusions.

[0024] Resin The resin is not particularly limited, but thermosetting resins and photocurable resins are preferred, and examples thereof include polyurethane-based resins such as polyurethanes having an ether or ester bond in the molecule and polyurethane polyureas; acrylic resins such as monofunctional acrylates, difunctional acrylates, polyfunctional acrylates, polyester acrylates, polyurethane acrylates, epoxy acrylates, acrylic phenolic resins, and polyacrylonitrile; vinyl resins such as polyvinyl chloride, polyvinyl acetate, and polyvinylidene fluoride; polysulfone-based resins such as polysulfone and polyethersulfone; acylated cellulose-based resins such as acetylated cellulose and butyrylated cellulose; polyamide-based resins; and polystyrene-based resins, unsaturated polyester resins, phenolic resins, urea resins, melamine resins, polyimide resins, alkyd resins, phenol-modified alkyd resins, and cellulose-based resins.

[0025] Among these, acrylic resins, polyurethane resins, unsaturated polyester resins, and phenol-modified alkyd resins are preferred, and three-dimensionally crosslinked acrylic resins are more preferred. By using such resins, the polishing rate tends to be further improved. The resins constituting the polishing part may be used alone or in combination of two or more.

[0026] 1.2.2. Composite fine particles The composite microparticles contain diamond abrasive grains as abrasive microparticles, which are components that contribute to polishing. The composite microparticles may contain matrix particles in addition to diamond abrasive grains. They may also contain other abrasive microparticles, auxiliary particles, etc. Here, the matrix particles are a solid dispersion medium for the abrasive microparticles, which are dispersoids. Because they are in particulate form during the manufacturing process, they are referred to as "matrix particles" for convenience, but in the composite microparticles of this embodiment, the matrix particles are fused to each other and do not need to be particles. In other words, the abrasive microparticles may be dispersed in the fused matrix particles. Furthermore, the auxiliary particles may be particles added to suppress blocking between the composite microparticles.

[0027] Among these, it is preferable that the composite particles contain diamond abrasive grains and matrix particles, which increases the polishing efficiency because new abrasive particles are exposed from the inside as the matrix particles wear.

[0028] The crushing strength (Cs) of the composite microparticles is 100.0 to 300.0 MPa, preferably 110.0 to 280.0 MPa, and more preferably 120.0 to 260.0 MPa. A crushing strength of 100.0 MPa or more can prevent the abrasive microparticles from easily detaching from the composite microparticles, which tends to prevent a decrease in the polishing rate. In addition, scratches on the workpiece caused by the rolling of detached diamond abrasive grains tend to be prevented. A crushing strength of 300.0 MPa or less can prevent scratches on the workpiece caused by the diamond abrasive grains being fixed in a protruding state on the polishing surface after the dressing process, which tends to prevent a deterioration in surface roughness.

[0029] The standard deviation (SD) of the crushing strength of the composite particles is preferably 15.0 to 170.0 MPa, more preferably 30.0 to 165.0 MPa, and even more preferably 50.0 to 160.0 MPa. When the standard deviation is within the above range, a predetermined variation in the crushing strength of the composite particles occurs. In other words, both easily abradable composite particles and less easily abradable composite particles are present, which tends to improve the self-dressing properties of the polishing pad and the removal rate.

[0030] In the present invention, the "crushing strength" can be determined by measuring the crushing strength of five composite microparticles using the crushing strength measurement method described below and calculating the average value. The crushing strength can be adjusted by the firing temperature, firing time, and firing atmosphere, such as the amount of oxygen, when preparing the composite microparticles.

[0031] The value (SD / Cs) obtained by dividing the standard deviation (SD) of the crushing strength of the composite particles by the crushing strength (Cs) is preferably 15.0 to 70.0%, more preferably 25.0 to 68.0%, and even more preferably 30.0 to 65.0%. When the value (SD / Cs) obtained by dividing the standard deviation (SD) of the crushing strength by the crushing strength (Cs) is within the above range, a predetermined variation in the crushing strength of the composite particles occurs. In other words, both easily abradable composite particles and less easily abradable composite particles are present, which tends to improve the self-dressing property of the polishing pad and the removal rate.

[0032] The average particle diameter (Da) of the composite fine particles is preferably 10 to 100 μm, more preferably 25 to 95 μm, and even more preferably 35 to 90 μm. When the average particle diameter is within the above range, the composite fine particles are less likely to detach from the polishing pad, the polishing rate is more stably maintained, and the surface roughness of the resulting polished object tends to be reduced.

[0033] In the present invention, the term "average particle size" refers to the particle size at which the cumulative particle volume accounts for 50% of the total in a particle size distribution graph with particle size on the horizontal axis and cumulative particle volume on the vertical axis. Such an average particle size is also called the median diameter or d50. The particle size distribution graph can be obtained by a laser diffraction scattering method or the like.

[0034] The content of the composite particles is preferably 1.5 to 40.0 mass% relative to the total mass of the polishing part, more preferably 2.5 to 35.0 mass%, and even more preferably 3.5 to 10.0 mass%. When the content of the composite particles is 1.5 mass% or more, the polishing rate tends to be further improved. Furthermore, when the content of the composite particles is 40.0 mass% or less, the grinding force tends to be further improved.

[0035] 1.2.2.1. Abrasive particles The components constituting the abrasive particles are not particularly limited as long as they contain diamond abrasive grains, but they are the hardest material in the polishing pad and are composed of the components with the highest grinding ability. In addition to diamond abrasive grains, for example, cubic boron nitride, green silicon carbide, silicon carbide, cerium oxide, silicon carbide, boron carbide, silicon oxide, zirconium oxide, iron oxide, aluminum oxide, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, zirconium silicate, boron nitride, silicon nitride, barium carbonate, and calcium carbonate can be mentioned. Among them, diamond abrasive grains have the best grinding ability. These abrasive particles can be used alone or in combination of two or more types.

[0036] The average particle diameter (Dd) of the abrasive particles varies depending on the object to be polished and the process, but is preferably 1.0 to 20.0 μm, more preferably 2.0 to 12.5 μm, and even more preferably 3.0 to 10.0 μm. By having the average particle diameter within the above range, it tends to be possible to prevent the abrasive particles from forming deep scratches on the object to be polished.

[0037] The ratio (Dd / Da) of the average particle size (Dd) of the abrasive fine particles to the average particle size (Da) of the composite fine particles is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20. When the average particle size ratio (Dd / Da) is within the above range, the abrasive fine particles that do not cause deep scratches are less likely to detach from the polishing pad, and the surface roughness of the resulting polished object tends to be reduced while maintaining a more stable removal rate.

[0038] The content of the abrasive particles is preferably 1.0 to 30.0 mass % relative to the total amount of the composite particles, more preferably 3.0 to 20.0 mass %, and even more preferably 5.0 to 15.0 mass %. When the content of the abrasive particles is within the above range, there are an adequate number of contact points between the abrasive particles and the workpiece to be polished, and the load on each abrasive particle is not too large, so the polishing rate is maintained more stably and the surface roughness of the resulting workpiece tends to be reduced.

[0039] 1.2.2.2. Matrix particles The components constituting the matrix particles are not particularly limited, but may include at least one selected from the group consisting of silicon dioxide, boron oxide, zinc oxide, boric acid, sodium tetraborate, aluminum oxide, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate, potassium carbonate, lithium carbonate, silver carbonate, potassium nitrate, copper(I) oxide, copper(II) oxide, silver oxide, bismuth oxide, and titanium oxide. Among these, silicon dioxide, boron oxide, and zinc oxide are preferred. More preferred is the use of glass frit, which is obtained by melt-molding a glass material primarily composed of silicon dioxide, boron oxide, and zinc oxide and then powdering it. The use of such matrix particles results in composite particles strong enough to hold abrasive particles without crushing the composite particles due to grinding of the matrix particles during conditioning. This tends to maintain more stable polishing while reducing the surface roughness of the resulting polished object. These matrix particles may be used alone or in combination.

[0040] The powdered matrix particles preferably have an average particle size of 1.0 to 20 μm, more preferably 2.0 to 12.5 μm, and even more preferably 3.0 to 10 μm. If the average particle size is about the same as that of the abrasive particles, the distribution in the composite particles tends to be uniform, which is preferable as it reduces variations in grinding ability between the composite particles.

[0041] The ratio of the average particle size of the matrix particles to the average particle size of the composite fine particles is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20. When the average particle size ratio is within the above range, the abrasive fine particles are excellently fixed when the composite particles are formed, the polishing rate can be more stably maintained, and the surface roughness of the resulting polished object tends to be further reduced.

[0042] The content of the matrix particles is preferably 10 to 98 mass %, more preferably 25 to 95 mass %, and even more preferably 50 to 90 mass %, of the total amount of the composite particles. When the content of the matrix particles is within the above range, the spacing between the abrasive particles increases, the contact points between the abrasive particles and the workpiece during polishing are reduced, the load per abrasive particle increases, and the grinding force increases, tending to improve the polishing rate.

[0043] 1.2.2.3. Auxiliary particles The auxiliary particles are not particularly limited, but examples thereof include auxiliary particles having an average particle diameter of 0.5 to 4.5 μm. By using such auxiliary particles, blocking between the composite fine particles is suppressed, and the polishing rate tends to be improved. The auxiliary particles may be located on the surface of the composite fine particles.

[0044] The components constituting such auxiliary particles are not particularly limited, but may include, for example, at least one selected from the group consisting of white alumina abrasive grains, brown alumina abrasive grains, black silicon carbide abrasive grains, green silicon carbide abrasive grains, barium sulfate, cerium oxide, etc. By using auxiliary particles containing such components, blocking between composite fine particles tends to be suppressed, and the polishing rate tends to be improved. These auxiliary particles may be used alone or in combination of two or more types.

[0045] The average particle size of the auxiliary particles is preferably 0.5 to 4.5 μm, more preferably 0.7 to 4.0 μm, and even more preferably 0.9 to 3.5 μm. By having the average particle size within the above range, blocking of the composite fine particles can be effectively suppressed, the effect of improving the polishing rate can be easily obtained, and the surface roughness of the obtained polished object can be further reduced.

[0046] The content of the auxiliary particles is preferably 1.0 to 60.0 mass %, more preferably 10.0 to 55.0 mass %, and even more preferably 30.0 to 50.0 mass %, relative to the total amount of the composite fine particles. When the content of the auxiliary particles is within the above range, blocking of the composite fine particles can be effectively suppressed, the effect of improving the polishing rate can be easily obtained, and the surface roughness of the obtained polished object tends to be further reduced.

[0047] The content of the auxiliary particles is preferably 1.0 to 10 mass %, more preferably 1.5 to 7.5 mass %, and even more preferably 1.5 to 5.0 mass %, relative to the total amount of the polishing part. When the content of the auxiliary particles is within the above range, blocking of the composite fine particles can be effectively suppressed, the effect of improving the polishing rate can be easily obtained, and the surface roughness of the obtained polished object tends to be further reduced.

[0048] 1.2.3.Spacer particles Examples of spacer particles include inorganic particles with a Mohs hardness lower than that of the abrasive particles. The shape of the inorganic particles is not particularly limited, but examples include whisker-like, columnar, flaky, and scaly shapes. Furthermore, the components constituting such inorganic particles are not particularly limited, but examples include silicate minerals such as potassium aluminum silicate (Mohs hardness 6), diatomaceous earth (Mohs hardness 6-7), and wollastonite (Mohs hardness 4.5-5); metal oxides such as iron oxide (Mohs hardness 6), titanium oxide (Mohs hardness 6.5), zinc oxide (Mohs hardness 4), and alumina (Mohs hardness 9); metal carbonates such as calcium carbonate (Mohs hardness 3) and magnesium carbonate (Mohs hardness 3.5); and metal sulfates such as calcium sulfate (Mohs hardness 3.5) and barium sulfate (Mohs hardness 3-3.5). Among these, wollastonite is preferred from the viewpoints of the fixing power and self-dressing properties of the composite particles.

[0049] Wollastonite is a silicate mineral containing calcium silicate (CaSiO3) and is also known as wollastonite. In addition to calcium, wollastonite may also contain silicates of other metals, such as iron, manganese, sodium, and lithium. The use of wollastonite allows the polishing rate to be maintained more stably and the surface roughness of the resulting polished object to be reduced.

[0050] The average particle size of the spacer particles is 5.0 to 20 μm, preferably 7.5 to 17.5 μm, and more preferably 10 to 15 μm. When the average particle size is within this range, when mixed with a resin, the viscosity is low and the flowability is high, resulting in excellent moldability. In addition, the disintegration of the polishing area is improved, the polishing rate is maintained, and scratches tend to be more suppressed.

[0051] The ratio of the average particle size of the composite fine particles to the average particle size of the spacer particles is preferably 1.5 to 10, more preferably 2.5 to 9.0, and even more preferably 3.5 to 8.0. When the ratio is 1.5 or more, the spacer particles can be densely packed around the composite abrasive grains, making it easier to fix the composite fine particles. When the ratio is 10 or less, the grinding force can be increased without being pressed into the polishing pad during polishing. By keeping the ratio within the above range, the surface quality of the polished object can be more stably maintained.

[0052] The aspect ratio of the spacer particles (average major axis diameter / average minor axis diameter) is 2.0 to 12, preferably 2.5 to 10, and more preferably 3.0 to 7.0. When the aspect ratio (average major axis diameter / average minor axis diameter) is within the above range, appropriate self-dressing properties are obtained, the polishing rate can be more stably maintained, and the surface roughness of the resulting polished object is further reduced. The method for measuring the aspect ratio of the spacer particles is not particularly limited, but it can be calculated from photographs taken with an electron microscope.

[0053] The content of the spacer particles is preferably 40 to 70 mass %, more preferably 45 to 65 mass %, and even more preferably 50 to 60 mass %, relative to the total amount of the polishing part. When the content of the spacer particles is within the above range, new composite fine particles can continue to appear due to the self-dressing property of the spacer particles, which tends to stabilize the polishing rate and further reduce the surface roughness of the polished object.

[0054] The ratio of the spacer particle content to the composite particle content is preferably 1.5 to 22.5, more preferably 2.5 to 17.5, and even more preferably 5.0 to 12.5. When the ratio of the spacer particle content to the composite particle content is within the above range, the spacing between the composite particles becomes appropriate, the load on the composite particles is easily equalized, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.

[0055] 1.3.Adhesive layer The polishing pad of this embodiment may further include an adhesive layer on the opposite side of the substrate from the polishing portion for attaching the polishing pad to the polishing platen of a polishing machine. The adhesive layer may contain an adhesive or pressure-sensitive adhesive used in conventionally known polishing pads.

[0056] Examples of materials for the adhesive layer include various thermoplastic adhesives such as acrylic adhesives, nitrile adhesives, nitrile rubber adhesives, polyamide adhesives, polyurethane adhesives, polyester adhesives, silicone adhesives, etc. The adhesive layer may also be, for example, double-sided tape.

[0057] 2. Manufacturing method of polishing pad The method for manufacturing a polishing pad of this embodiment includes a firing step of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles, a curing step of curing a curable composition containing a resin and the composite microparticles to obtain a polishing part, and a bonding step of bonding the surface of the polishing part opposite the polishing surface to a substrate, and the crushing strength of the composite microparticles is 100 to 300 MPa.

[0058] 2.1. Firing process The firing step is a step of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles. The firing step may include a composite microparticle precursor preparation step containing diamond abrasive grains and matrix particles. In the firing step, the composite microparticle precursor obtained by the composite microparticle precursor preparation step described below is fired to thermally decompose the binder resin in the composite microparticle precursor, and fuse the matrix particles together to form an appropriate bond.

[0059] In the firing step, in addition to the composite particle precursor containing diamond abrasive grains and matrix particles, the above-mentioned auxiliary particles may also be included and fired. By including the auxiliary particles, blocking between the composite particle precursors can be suppressed.

[0060] The firing temperature in the firing step is preferably equal to or higher than the deformation point of the matrix particles. If the firing temperature is equal to or higher than the deformation point of the matrix particles, the matrix particles tend to fuse together and bond appropriately, which tends to further improve the stability of the composite microparticles. If the firing temperature is too low, the matrix particles do not bond together, making it difficult to produce the composite microparticles.

[0061] The firing temperature is preferably the deformation point of the matrix particle + 150 ° C or less, more preferably the deformation point of the matrix particle + 120 ° C or less, even more preferably the deformation point of the matrix particle + 100 ° C or less, and even more preferably the deformation point of the matrix particle + 80 ° C or less. The lower limit of the firing temperature is preferably equal to or higher than the deformation point of the matrix particle. When the firing temperature is equal to or lower than the deformation point of the matrix particle + 150 ° C, the composite particles tend to be prevented from bonding together, while the diamond abrasive grain retention force of the composite particles tends to be within a suitable range. In addition, if the firing temperature is too high, the composite particles will bond together and will need to be crushed after firing, which may cause the shape of the composite particles to become distorted, and may impair the abrasive grain retention force of the composite particles.

[0062] The firing temperature also depends on the yield point of matrix particles, but is preferably 500 to 700 ° C, more preferably 530 to 670 ° C, even more preferably 550 to 650 ° C, and even more preferably 570 ° C to 630 ° C. When the firing temperature is within the above range, it tends to be possible to suppress the bonding of composite particles, while making the holding power of diamond abrasive grains that composite particles have within a suitable range.In addition, if the firing temperature is too high, the composite particles will bond together and need to be crushed after firing, so the shape of the composite particles will become distorted, and the holding power of the abrasive grains that composite particles have may be impaired.

[0063] The firing time in the firing step is, for example, 0.5 to 30 hours, and may be adjusted appropriately to obtain the desired composite fine particles.

[0064] The atmosphere in the firing step is not particularly limited, but is preferably an air atmosphere. In an air atmosphere, the matrix particles tend to fuse together and bond appropriately, and the variation in the crushing strength of the composite microparticles tends to be stabilized.

[0065] The atmosphere in the firing process is not particularly limited, but is preferably an open system. In this specification, an open system refers to a system in which the firing container is not sealed and the air atmosphere, which is the firing atmosphere, can flow in and out. The firing apparatus may be either a static firing furnace or a fluidized firing furnace. When a static firing furnace is used, the fired material is fired in a container such as a sheath. In this case, a temperature difference occurs between the contact portion between the composite particles and the sheath and the central portion of the composite particles, or between the composite particles in contact with the firing atmosphere and the composite particles not in contact with the firing atmosphere, which tends to result in a difference in thermal history. Therefore, a moderate variation in the thermal history of the composite particles occurs, and the crushing strength of the composite particles can be set within a suitable range. Furthermore, the variation in the crushing strength of the composite particles can be set within a suitable range. In other words, both easily abradable and less abradable composite particles can be present, which tends to improve the self-dressing properties of the polishing pad and the polishing rate. The crushing strength can be adjusted to a suitable range by adjusting the baking time.

[0066] 2.1.1. Composite particle precursor production process The composite microparticle precursor preparation step may be a step of mixing diamond abrasive grains, matrix particles, a binder resin, a dispersant, and a solvent to prepare a composite microparticle precursor composition, and then granulating the composite microparticle precursor.

[0067] As the binder resin, a resin that can bind diamond abrasive grains and matrix particles and can be thermally decomposed by the following firing process is preferred.Water-soluble resin is more preferred, and as such a resin, a general-purpose binder can be used.For example, dextrin, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, and polyacrylamide can be mentioned, and dextrin is preferred.In addition, these binder resins can be used alone or in combination of two or more.

[0068] The dispersant is not particularly limited, but examples thereof include quaternary ammonium salts, polycarboxylic acid surfactants, and maleic anhydride surfactants.

[0069] Examples of the solvent (dispersion liquid containing the binder resin) include water and alcohols such as methanol and isopropanol, and water is preferred. These solvents may be used alone or in combination of two or more.

[0070] In addition to the above components, other additives may be added to the composite fine particle precursor composition. Examples of other additives include deflocculants (dispersants) and surfactants. These additives may be used alone or in combination of two or more.

[0071] The method for granulating the composite microparticle precursor composition is not particularly limited, but may include a method using a spray dryer such as a spray dryer. In this method, the precursor composition is sprayed into heated air and the solvent (dispersion) is evaporated to obtain precursor particles. The granulation conditions are not particularly limited and can be appropriately set depending on the desired composite microparticles. The drying temperature in the spray drying is not particularly limited as long as it is a temperature at which the solvent can be evaporated, and may be 150 to 250°C, for example, when water is used as the solvent.

[0072] 2.2.Curing process The curing step is a step of obtaining a polishing part by curing a curable composition containing a resin and composite fine particles.

[0073] 2.2.1. Curable composition The curable composition is not particularly limited as long as it contains a resin and composite fine particles, and examples thereof include a photocurable composition containing a photopolymerization initiator and a polymerizable compound, a thermosetting composition containing a thermal polymerization initiator and a polymerizable compound, a UV-curable resin, a curable composition containing a two-component mixed curable resin, etc. Furthermore, the curable composition may contain a crosslinking agent having two or more polymerizable functional groups, etc., as necessary.

[0074] The polymerizable compound is not particularly limited, but examples thereof include (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

[0075] The photopolymerization initiator is not particularly limited, but examples thereof include phosphine oxide compounds, benzophenone compounds, acetophenone compounds, and thioxanthone compounds. The thermal polymerization initiator is not particularly limited, but examples thereof include azo compounds such as 2,2'-azobisbutyronitrile, and peroxides such as benzoyl peroxide (BPO).

[0076] The thermosetting resin is not particularly limited, but examples thereof include urethane resin, unsaturated polyester resin, alkyd resin, phenol resin, epoxy resin, acrylic resin, urea resin, and formaldehyde resin.

[0077] The UV-curable resin is not particularly limited, but for example, a prepolymer with a number-average molecular weight of about 1,000 to 10,000 is suitable, and examples of materials include acrylic (methacrylic) esters, their urethane-modified products, thiocol-based materials, etc., and a reactive diluent or organic solvent can be used depending on the application. Furthermore, the two-component mixed curable resin is not particularly limited, but for example, prepolymers with different physical properties can be used.

[0078] The curable composition may contain components other than the resin, the composite fine particles, and the polymerization initiator, such as the filler and auxiliary particles described above.

[0079] 2.2.2.Curing method The method for curing the curable composition is not particularly limited, but examples thereof include photocuring, thermal curing, etc. The resulting polished portion has some of the composite fine particles exposed on the surface and the remaining composite fine particles bonded with the resin.

[0080] 2.3.Joining process The bonding step is a step of bonding the surface of the polishing part opposite the polishing surface to the substrate. The bonding method is not particularly limited, and the bonding step may be included in the curing step, or the polishing part and the substrate may be bonded by attaching the curable composition to the substrate and curing the curable composition, or the surface of the polishing part opposite the polishing surface that has been cured in advance may be bonded to the substrate via an adhesive.

[0081] The method for adhering the curable composition onto the substrate is not particularly limited, and examples thereof include a gravure coater method, a small-diameter gravure coater method, a reverse roll coater method, a transfer roll coater method, a kiss coater method, a die coater method, a screen printing method, a spray coating method, an embossing roll method, a transfer method, etc. Among these, the screen printing method or the transfer method is preferred from the viewpoints of ease of forming a complex concavo-convex pattern and productivity.

[0082] In the screen printing method, for example, a plate with an opening pattern corresponding to the convex portions is prepared, gaps are formed on a PET sheet serving as the substrate layer, the plate is placed, and the abrasive layer material is placed on the plate. A moderate amount of pressure is applied to the squeegee, and the abrasive layer material is pressed against the openings in the plate while the squeegee is moved, extruding and printing the abrasive layer material. The abrasive layer material is then cured to obtain a polishing pad consisting of a patterned abrasive layer on the substrate layer. In the transfer method, for example, a transfer mold with recesses corresponding to the convex portions is prepared, and the abrasive layer material is filled into this transfer mold. The filled abrasive layer material is then bonded to a substrate such as a PET sheet or acrylic sheet serving as the substrate layer via an adhesive. The abrasive layer material is then cured by irradiating it with light from above the PET sheet, and the sheet is then peeled off from the transfer mold, and if necessary, the convex portions are irradiated with light again to harden it, thereby obtaining a polishing pad consisting of a patterned abrasive layer on the substrate layer.

[0083] The method may further include a step of bonding the substrate on which the polishing portion is disposed to another substrate. In this step, the surface of the substrate opposite to the surface on which the polishing portion is disposed is bonded to the other substrate via an adhesive. The type of adhesive used is not particularly limited, and may be a liquid adhesive, double-sided tape, or adhesive tape made by processing an adhesive into a tape shape. Examples of liquid adhesives include curable adhesives such as photocurable resins, thermosetting resins, and moisture-curable resins, solvent-volatile adhesives, and hot-melt adhesives.

[0084] The adhesive can be applied by any conventionally known method, such as printing, typically screen printing, spray application, or application with a roller or brush.

[0085] The type of adhesive used to bond the surface of the pre-cured abrasive portion opposite the abrasive surface to the substrate is not particularly limited, and any of the above-mentioned adhesives may be used as appropriate.

[0086] 2.4.Other processes The method for producing a polishing pad of this embodiment may include other processes as necessary. For example, it may include a process of volatilizing and removing at least a portion of the volatile components in the curable composition before the curing process. Furthermore, it may include a process of removing a portion of the curable composition or the polishing portion before and / or after the curing process to form a desired uneven pattern. Examples of the removal method include cutting.

[0087] 3. Manufacturing method of polished products The method for producing a polished product of this embodiment is not particularly limited as long as it includes a polishing step of polishing an object to be polished using the polishing pad. The polishing step may be a primary lapping step (rough lapping), a secondary lapping step (finish lapping), or a polishing step, or may be a step that combines two or more of these steps. In addition, a coolant may be used in the polishing.

[0088] The polished object is not particularly limited, but examples thereof include materials such as semiconductor devices and electronic components, particularly thin substrates (polished objects) such as Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaN (gallium nitride) substrates, GaAs (gallium arsenide) substrates, sapphire substrates, glass, and substrates for hard disks and LCDs (liquid crystal displays). Among these, the method for manufacturing a polished product of this embodiment is suitable for manufacturing magnetic disks such as hard disk drives, glass substrates used as base materials for reflective masks used in lithography using EUV light, glass materials for LCD substrates and cover glasses of mobile terminals such as smartphones and tablets, sapphire substrates for LEDs, and difficult-to-cut materials such as SiC (silicon carbide) substrates, GaN (gallium nitride) substrates, and GaAs (gallium arsenide) substrates.

[0089] 3.1. Polishing process The polishing step is a step of polishing an object to be polished using the polishing pad in the presence of a coolant. The polishing method may be any conventionally known method, and is not particularly limited.

[0090] In this polishing method, a polishing pad is first mounted in a predetermined position on a polishing apparatus. During this mounting, the polishing pad is fixed to the polishing apparatus via the adhesive layer. Then, a workpiece held on a holding platen, which is positioned opposite the polishing pad as a polishing surface, is pressed against the polishing surface, and the polishing pad and / or holding platen are rotated while supplying coolant from outside. This reduces polishing resistance and removes polishing debris due to the action of the coolant supplied between the polishing pad and the workpiece, while polishing the workpiece surface (surface to be polished). [Example]

[0091] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0092] [Preparation Example 1] (Preparation of Composite Microparticles) 12 parts by weight of dextrin (manufactured by Tokai Dextrin), 40 parts by weight of purified water, 1 part by weight of additive Cerna D-735 (manufactured by Chukyo Yushi), 42 parts by weight of glass frit, and 5 parts by weight of diamond powder with an average particle size of 3 μm were mixed to prepare a slurry. Then, the mixture was spray-dried using a spray dryer to form a composite particle precursor. Next, 120 g of the composite particle precursor was mixed with 120 g of white alumina (manufactured by Fujimi Co., Ltd., average particle size 3 μm) and placed in an open-top alumina sintering sheath measuring 120 mm x 120 mm x 60 mm. The mixture was heated from room temperature to 400 ° C at a rate of 2 ° C / min in a muffle furnace, held for 1 hour, then heated to 590 ° C at a rate of 2 ° C / min, held for 2 hours, and then cooled to room temperature at a rate of 5 ° C / min to obtain composite particles A with an average particle size of 40 μm.

[0093] [Preparation Example 2] Composite fine particles B having an average particle size of 40 μm were obtained in the same manner as in Preparation Example 1, except that the firing was carried out at 580°C.

[0094] [Preparation Example 3] Composite fine particles C having an average particle size of 40 μm were obtained in the same manner as in Preparation Example 1, except that the firing was carried out at 610°C.

[0095] [Preparation Example 4] Composite fine particles D having an average particle size of 40 μm were obtained in the same manner as in Preparation Example 1, except that diamond powder having an average particle size of 9 μm was used.

[0096] [Preparation Example 5] Composite particles E having an average particle size of 40 μm were obtained in the same manner as in Preparation Example 1, except that the mixture was placed in a container sealed with a lid and fired at 580° C. for 2 hours.

[0097] Preparation Example 6 Composite particles F having an average particle size of 40 μm were obtained in the same manner as in Preparation Example 1, except that a rotary kiln, which is a fluidized bed furnace, was used as the firing apparatus and the composite particles were fired while being stirred in the furnace at 5 rpm.

[0098] Example 1 (Preparation of Curable Composition) A precursor composition was prepared by mixing 96.9 parts by mass of a mixture (SR368D manufactured by Sartomer Corporation) of trimethylolpropane triacrylate:tris(2-hydroxyethyl)isocyanurate triacrylate = 70:30 (mass ratio), 1.6 parts by mass of a dispersant (Solsperse 32000 manufactured by Lubrizol Japan Co., Ltd.), 1.0 part by mass of a photopolymerization initiator (Irgacure 819 manufactured by BASF Japan Ltd.), and 0.5 parts by mass of a photosensitizer (Anthracure (registered trademark) UVS-581 manufactured by Kawasaki Chemical Industries, Ltd.).

[0099] Next, 5 parts by mass of composite particles A, 37 parts by mass of the precursor composition, and 58 parts by mass of wollastonite (K-400, manufactured by Keiwa Fine Material Co., Ltd., average particle size 11 μm, aspect ratio 6) were mixed to prepare a curable composition.

[0100] (Preparation of polishing pads) The obtained curable composition was poured into a moldable silicone intaglio plate having a rectangular prism-shaped recess with a depth of 1 mm, a cavity opening dimension of 3.0 mm × 3.0 mm, a recess bottom dimension of 2.4 mm × 2.4 mm, and a spacing of 1 mm between adjacent openings. A single-sided tape was attached so that the upper surface of the curable composition and the adhesive layer of the single-sided tape were in contact, and the curable composition was cured by irradiating ultraviolet light from above with an ultraviolet irradiator. The obtained cured product (abrasive part) was then removed from the mold, and a 1 mm thick acrylic substrate was bonded to the ultraviolet-irradiated surface via double-sided tape. The surface that had been in contact with the silicone intaglio plate was then irradiated with ultraviolet light using an ultraviolet irradiator and heated in a dryer at 90 ° C for 12 hours, obtaining a polishing pad of Example 1 with a diameter of 300 mm.

[0101] [Examples 2 to 4, Comparative Examples 1 and 2] Polishing pads were obtained in the same manner as in Example 1, except that composite particles B, C, D, E and F were used instead of composite particles A.

[0102] [Average particle size of diamond abrasive grains and composite microparticles] The average particle size (d50%) at which the cumulative value from the smallest diameter in the cumulative volumetric particle size distribution reached 50% of the total was measured in 10 seconds using a laser diffraction particle size distribution analyzer "Microtrac MT3300EXII" manufactured by Microtrac Bell Co., Ltd. The refractive index used during the measurement was 1.61, and the refractive index of the medium (deionized water) was 1.333.

[0103] [Crushing strength] Five composite particles were randomly selected, and using a microcompression tester (Shimadzu Corporation: MCT-510) and an indenter (Shimadzu Corporation: FLAT200), the composite particles were compressed one by one at a loading rate of 51.8527 mN / sec, and the test force P (mN) at the time of fracture was measured. The crushing strength (Cs) was measured in accordance with JIS R1639-5:2007 and was calculated from the test force P (mN) and the average particle diameter (d50%) of the composite particles using the following formula (where π is the ratio of the circumference of the circle to its diameter). The average crushing strength for the five particles is shown in Table 1. Crushing strength (Cs)=2.48×P / πd 2 In addition, the arithmetic mean of the crushing strength P was taken, and the standard deviation (the positive square root of the sum of the squares of the differences between each data value and the mean, divided by the total number of data n) was calculated as the variability. The standard deviation of the composite microparticles was divided by the average value of the crushing strength to determine the degree of variability (%) of the composite microparticle strength.

[0104] [Grinding test] A glass grinding test was carried out on the polishing pads of each of the Examples and Comparative Examples under the following test conditions, and the surface roughness of the glass and the polishing rate after the test were measured. (Grinding conditions) Testing machine: Friction and wear testing machine Speedfam tabletop polishing machine (plate size 305mmφ) Dresser: WA whetstone #1000 Dressing time: 5 to 20 minutes Load: 200g / cm 2 Rotation speed: 80 rpm Time: 10 minutes / batch x 7 batches Coolant: Subrelve 9016 (Chemetall) 10 times diluted aqueous solution Fluid volume: 30mL / min Grinding material: Glass (50mm x 50mm)

[0105] (surface roughness Ra of the workpiece) The surface roughness Ra of the surface of the workpiece after grinding was measured using an optical interferometer (manufactured by Canon, trade name "Zygo NewView 5010"). (Evaluation criteria) ○: Glass surface roughness Sa is less than 40 nm ×: Glass surface roughness Sa is 40 nm or more

[0106] (removal rate, removal rate stability) The polishing rate represents the amount of polishing per minute, and was calculated from the loss in the mass of the glass before and after polishing. The removal rates of the 7th batch and the 3rd batch were measured, and the stability was calculated based on the following formula. Polishing rate stability (%)=(polishing rate for 7th batch of glass−polishing rate for 3rd batch of glass) / polishing rate for 7th batch of glass×100 The polishing rate stability was evaluated according to the following criteria. (Polishing rate evaluation standard) 〇:20mg / min or more ×: Less than 20 mg / min (Polishing rate stability evaluation standard) ○: Less than 10% ×: 10% or more

[0107] [Table 1]

[0108] As described above, the polishing pad of the present invention has a polishing portion comprising resin and composite microparticles, the composite microparticles comprising diamond abrasive grains, and the crushing strength of the composite microparticles is 100 to 300 MPa, thereby exhibiting a stable polishing rate, providing good surface roughness for the object to be polished, and high planarization accuracy.

[0109] On the other hand, in Comparative Example 1, the crushing strength of the composite microparticles was extremely low, so the diamond abrasive grains were easily detached from the composite microparticles, reducing the polishing rate, and the large variation in crushing strength meant that the polishing rate was unstable, and the detached diamond abrasive grains also caused the surface roughness to deteriorate.In Comparative Example 2, the crushing strength of the composite microparticles was low, so the composite microparticle shell diamond abrasive grains were detached, reducing the polishing rate, and the detached diamond abrasive grains also caused the surface roughness to deteriorate. [Industrial Applicability]

[0110] The polishing pad of the present invention has industrial applicability as a polishing pad suitable for lapping and polishing optical materials, semiconductor devices, glass substrates for hard disks, sapphire substrates for LEDs, and difficult-to-cut materials such as SiC (silicon carbide) substrates, GaN (gallium nitride) substrates, and GaAs (gallium arsenide) substrates. [Explanation of symbols]

[0111] 10... Polishing pad, 11... Base material, 12... Polishing portion, 14... Composite fine particles, 15... Resin

Claims

1. A substrate and an abrasive portion disposed on the substrate, the polishing portion includes a resin and composite fine particles, The composite microparticles include diamond abrasive grains, The crushing strength (Cs) of the composite microparticles is 100.0 to 300.0 MPa. Polishing pad.

2. the value (SD / Cs) obtained by dividing the standard deviation (SD) of the crushing strength of the composite microparticles by the crushing strength (Cs) is 15.0 to 70.0%; The polishing pad of claim 1 .

3. The standard deviation (SD) of the crushing strength of the composite microparticles is 15.0 to 170.0 MPa. The polishing pad of claim 1 .

4. The polishing portion has a convex portion. The polishing pad of claim 1 .

5. a firing step of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles; a curing step of curing a curable composition containing a resin and the composite fine particles to obtain a polishing part; a joining step of joining a surface of the polishing part opposite to the polishing surface to a substrate, The crushing strength of the composite microparticles is 100.0 to 300.0 MPa. A method for manufacturing a polishing pad.

6. A method for polishing an object to be polished using the polishing pad according to any one of claims 1 to 4, Manufacturing method for polished products.

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