Polishing pad and method of manufacturing the same

Abstract

To provide a polishing pad which has appropriate collapsibility, and thereby can stably maintain surface quality of a polished object, 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, polishing particles, and spacer particles, an average particle diameter D1 of the spacer particles is 3.5-15 μm, and an SD value in particle size distribution of the spacer particles is 3.0-10 μm.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] High smoothness and minimal micro-defects are required for the surfaces of various glass materials, such as magnetic disks in hard disk drives, glass substrates used as the base material for reflective masks used in EUV lithography, and glass substrates used as the material for LCD panels and cover glasses in mobile devices such as smartphones and tablets. Polishing pads containing abrasive particles are generally used to process the surfaces of such glass materials.

[0003] Specifically, an abrasive material having an abrasive layer containing two types of abrasive grains with different average particle sizes has been proposed (Patent Document 1), and a cutting tool having grinding grains, a binder that bonds the grinding grains, and dispersed grains that are harder than the binder but softer than the grinding grains has been proposed (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 163565 [Patent Document 2] Japanese Patent Application Publication No. 2018-092697 Summary of the Invention [Problem to be solved by the invention]

[0005] In the abrasive material described in Patent Document 1, it is described that abrasive grains with a small average particle size fall off first, accelerating the fall off of abrasive grains with a large average particle size, thereby maintaining grinding power. However, this technology has a high abrasive property on the polishing surface, which is prone to becoming rough, and therefore there is a limit to how much flatness can be improved on the surface of the workpiece being polished.

[0006] Furthermore, the cutting tool described in Patent Document 2 does not aim to maintain polishing performance by causing the abrasive grains to fall off, but rather aims to achieve both a high processing speed and high processing quality by dispersing the force of the grinding grains using dispersion particles. However, because this technology does not cause the grinding grains to fall off, it has the inherent problem of a decrease in the polishing rate over time.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a polishing pad and a method for manufacturing the same that have appropriate disintegratability and can stably maintain the surface quality of the object being polished. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by using spacer particles having a predetermined average particle diameter D1 and particle size distribution, thereby completing the present invention.

[0009] That is, the present invention is as follows. [1] A substrate and an abrasive portion disposed on the substrate, the abrasive portion includes a resin, abrasive particles, and spacer particles; the average particle diameter D1 of the spacer particles is 3.5 to 15 μm, The SD value of the particle size distribution of the spacer particles, which is represented by the following formula (1), is 3.0 to 10 μm. Polishing pad. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.) [2] The content of the spacer particles is 40 to 70 parts by mass relative to 100 parts by mass of the polishing part. The polishing pad according to [1]. [3] the content of the spacer particles having a particle diameter of 10 μm or less is 50 to 80 mass % relative to the total amount of the spacer particles; The polishing pad according to [1] or [2]. [4] the content of the spacer particles having a particle diameter of 50 μm or more is 1.0 to 3.0 mass % relative to the total amount of the spacer particles; The polishing pad according to any one of [1] to [3]. [5] The spacer particles have a needle shape. The polishing pad according to any one of [1] to [4]. [6] The content of the abrasive particles is 1.5 to 20 parts by mass relative to 100 parts by mass of the abrasive part. The polishing pad according to any one of [1] to [5]. [7] The average particle diameter D2 of the abrasive particles is 15 to 100 μm. The polishing pad according to any one of [1] to [6]. [8] the ratio (D2 / D1) of the average particle diameter D2 of the abrasive particles to the average particle diameter D1 of the spacer particles is 1.5 to 10; The polishing pad according to any one of [1] to [7]. [9] the abrasive particles include composite particles containing abrasive particulates and matrix particles, the matrix particles comprise glass frit; The polishing pad according to any one of [1] to [8].

[10] the abrasive particles contain at least one selected from the group consisting of diamond, cerium oxide, silicon carbide, silicon oxide, zirconia, iron oxide, aluminum oxide, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, zirconium silicate, boron nitride, silicon nitride, barium carbonate, and calcium carbonate; The polishing pad according to any one of [1] to [9].

[11] The polishing portion further contains auxiliary particles having an average particle diameter D3 of 0.5 to 4.5 μm. The polishing pad according to any one of [1] to

[10] .

[12] a depositing step of depositing a curable composition containing a resin, abrasive particles, and spacer particles on a substrate; a curing step of curing the adhered curable composition to obtain a polished portion, the average particle diameter D1 of the spacer particles is 3.5 to 15 μm, The SD value of the particle size distribution of the spacer particles, which is represented by the following formula (1), is 3.0 to 10 μm. A method for manufacturing a polishing pad. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.) [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a polishing pad that has appropriate disintegrability and is capable of stably maintaining the surface quality of a non-polished object, and a method for producing the same. [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. [Figure 3] 1 is an electron microscope photograph of wollastonite A used in Example 1. [Figure 4] 1 is an electron microscope photograph of wollastonite B used in Example 2. [Figure 5] 1 is an electron microscope photograph of wollastonite C used in Comparative Example 1. [Figure 6]1 is a graph showing the particle size distribution of wollastonite used in Examples and Comparative Examples. 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 an abrasive portion disposed on the substrate, the abrasive portion containing a resin, abrasive particles, and spacer particles, the average particle diameter D1 of the spacer particles being 3.5 to 15 μm, and the SD value of the particle size distribution of the spacer particles, as expressed by the following formula (1), being 3.0 to 10 μm. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.)

[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 12 and a polishing portion 11 disposed on the substrate 12. In Figure 1, a plurality of convex portions formed by the polishing portion 11 are disposed on the surface of the substrate 12, forming an uneven pattern.

[0015] The polishing portion 11 may form a concave-convex pattern together with the substrate 12 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 portion 11 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 11 of the polishing pad 10 according to this embodiment includes spacer particles and a matrix 15 that binds the abrasive particles 14 together. The abrasive portion 11 has controlled disintegration properties due to the inclusion of spacer particles having a predetermined average particle diameter D1 and particle size distribution. As a result, as polishing progresses, the polishing surface of the abrasive portion 11 is gradually scraped away, and a new polishing surface is formed in which the abrasive particles 14 embedded in the abrasive portion 11 are exposed. The matrix 15 includes a resin and spacer particles.

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

[0018] 1.1. Base material The substrate is not particularly limited, but examples thereof include polyester films such as polyethylene terephthalate film, polypropylene terephthalate film, and polybutylene terephthalate film; polyolefin films such as polyethylene (PE) film, polypropylene (PP) film, and ethylene-propylene copolymer film; polyether ether ketone (PEEK) film, polyphenylene sulfide (PPS) film, and polycarbonate film.

[0019] The substrate is not particularly limited as long as it is possible to form a resin on the upper surface thereof, as described below. Among these, polyester films are preferred from the viewpoints of chemical resistance, heat resistance, cost efficiency, etc.

[0020] 1.2. Polishing section The abrasive portion contains a resin, abrasive particles, spacer particles, and may contain other auxiliary particles as needed. The abrasive portion 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).

[0021] Among these, it is preferable that the polishing part has a regular uneven pattern from the viewpoint of supplying or discharging liquid components used during polishing, such as coolant, to the polishing surface. 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. Furthermore, the surface of the polishing part opposite the substrate serves as the polishing surface for polishing the workpiece.

[0022] The uneven pattern is not particularly limited as long as it has a portion that contacts the workpiece (protrusion) and a portion that does not contact the workpiece (recess). For example, as shown in FIG. 1, a positive pattern (a pattern having dot-shaped protrusions) in which polishing portions 11 are independently formed on a substrate 12; a negative pattern (a pattern having dot-shaped recesses) in which polishing portions are continuously formed on a substrate; The following patterns can be used: a pattern with donut-shaped convex portions; a pattern with roughly C-shaped convex portions; a pattern with concentric circular portions that contact the workpiece and portions that do not contact the workpiece; a pattern with lattice-shaped portions that contact the workpiece and portions that do not contact the workpiece; a pattern with radial portions that contact the workpiece and portions that do not contact the workpiece; a spiral pattern that contacts 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. By having such a concave-convex pattern, the discharge of polishing debris tends to be further improved.

[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 hemispherical, approximately hemispherical, spherical cap, approximately spherical cap, spherical band, approximately spherical band, semi-ellipsoidal, approximately semi-ellipsoidal, columnar (cylindrical, approximately cylindrical, elliptical cylinder, approximately elliptical cylinder, polygonal columnar), and frustum (circular truncated cone, approximately circular truncated cone, elliptical truncated cone, approximately elliptical truncated cone, polygonal truncated cone). Of the above, the frustum shape may be a frustum shape that expands from the substrate side toward the polishing surface side, or a frustum shape that expands 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 can be exemplified as the three-dimensional shape in a pattern having dot-shaped protrusions. Furthermore, when poured into a mold and cured, a shape that can be demolded is desirable.

[0024] Resin The resin is not particularly limited, but thermoplastic 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 phenolic alkyd resins are 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. Abrasive particles The abrasive particles may be particles consisting only of components that contribute to polishing, or may be composite particles consisting of components that contribute to polishing and a matrix component. Among these, the abrasive particles preferably include composite particles containing abrasive particles and matrix particles. This increases the polishing efficiency because new abrasive particles are exposed from the inside as the matrix particles wear.

[0027] The average particle diameter D2 of the abrasive particles is preferably 10 to 100 μm, more preferably 25 to 90 μm, and even more preferably 35 to 80 μm. When the average particle diameter D2 is within the above range, the abrasive particles are less likely to detach from the polishing pad, and the surface quality of the workpiece can be more stably maintained.

[0028] In this embodiment, the term "average particle size" refers to the d50 particle size (μm) when the cumulative value from the smallest diameter reaches 50% of the total in the cumulative distribution of particle sizes on a volume basis. In this embodiment, values ​​related to particle sizes, including the average particle size, can be measured, for example, by a laser diffraction particle size distribution analyzer described in the Examples.

[0029] The content of the abrasive particles is preferably 1.5 to 20 parts by mass, more preferably 2.5 to 15 parts by mass, and even more preferably 5.0 to 10 parts by mass, relative to 100 parts by mass of the abrasive part. When the content of the abrasive particles is 1.5 parts by mass or more, the polishing rate tends to be further improved. Furthermore, when the content of the abrasive particles is 20 parts by mass or less, the grinding force tends to be further improved.

[0030] 1.2.2.1. Abrasive particles The components constituting the abrasive particles are not particularly limited, but are preferably the hardest material in the polishing pad and the component with the highest grinding ability. For example, at least one selected from the group consisting of diamond, cerium oxide, silicon 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 may be used. Among these, diamond is preferred because it has the most excellent grinding ability. These components contributing to polishing may be used alone or in combination of two or more.

[0031] The average particle diameter D21 of the abrasive particles varies depending on the workpiece and the process, but is preferably 1.0 to 20 μm, more preferably 2.0 to 12.5 μm, and even more preferably 3.0 to 10 μm. By keeping the average particle diameter D21 within the above range, it is possible to prevent the abrasive particles from forming deep scratches on the workpiece.

[0032] The ratio (D21 / D2) of the average particle diameter D21 of the abrasive fine particles to the average particle diameter D2 of the abrasive 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 diameter ratio (D21 / D2) is within the above range, the abrasive fine particles that do not cause deep scratches are less likely to detach from the polishing pad, which tends to further improve the stability of the removal rate.

[0033] The content of the abrasive particles is preferably 3.0 to 30 parts by mass, more preferably 5.0 to 25 parts by mass, and even more preferably 10 to 20 parts by mass, relative to 100 parts by mass of the abrasive particles. 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 applied to each abrasive particle does not become too large, which tends to further improve the stability of the polishing rate.

[0034] 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 abrasive particles strong enough to hold abrasive particles without crushing the abrasive particles due to grinding of the matrix particles during conditioning, thereby maintaining more stable polishing and tending to reduce the surface roughness of the resulting polished object. These matrix particles may be used alone or in combination.

[0035] The powdered matrix particles preferably have an average particle diameter D22 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 diameter D22 is about the same size as the fine abrasive particles, the distribution within the abrasive particles tends to be uniform, which is preferable as it reduces variations in grinding ability between the abrasive particles.

[0036] The ratio (D22 / D2) of the average particle size D2 of the matrix particles to the average particle size D2 of the abrasive 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 (D22 / D2) is within the above range, the fixing force of the abrasive particles is excellent when the composite particles are formed, and the stability of the polishing rate tends to be further improved.

[0037] The content of the matrix particles is preferably 40 to 97 parts by mass, more preferably 45 to 95 parts by mass, and even more preferably 50 to 90 parts by mass, per 100 parts by mass of the abrasive 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.

[0038] 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, flake-like, and scaly shapes. 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 in terms of the fixing power of the abrasive particles and self-dressing properties.

[0039] 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. By using wollastonite, the surface quality of the workpiece can be more stably maintained.

[0040] The average particle diameter D1 of the spacer particles is 3.5 to 15 μm, preferably 4.0 to 12.5 μm, and more preferably 4.5 to 10 μm. If the average particle diameter D1 is larger than 15 μm, the aspect ratio of the spacer particles will have an effect, and the viscosity will increase when mixed with a resin, resulting in poor moldability. If the diameter is within the above range, the viscosity will be low and the fluidity will be high when mixed with a resin, resulting in excellent moldability.

[0041] The average particle diameter D1 of the spacer particles in the polishing pad can be measured by a known method. For example, the polishing pad is heated to 550°C or the like, the sample is ashed, and the roughly spherical abrasive particles are removed to extract the spacer particles from the polishing pad. The spacer particles are then thoroughly dispersed using an ultrasonic disperser or the like to prepare a dispersion. Using this dispersion, the average particle diameter of the spacer particles can be measured from the particle size distribution measured using a laser diffraction / scattering particle size distribution analyzer. Alternatively, the average particle diameter of the spacer particles can be measured from the volume-based particle size distribution obtained by observing the polishing pad surface with a scanning electron microscope and analyzing the images.

[0042] The ratio (D2 / D1) of the average particle diameter D2 of the abrasive particles to the average particle diameter D1 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 (D2 / D1) is 1.5 or more, the spacer particles can be densely packed around the composite abrasive grains, making it easier to fix the composite abrasive grains. When the ratio is 10 or less, the grinding force can be increased without forcing the composite abrasive grains into the pad during polishing. By keeping the ratio within the above range, the surface quality of the polished object can be more stably maintained.

[0043] The SD value, expressed by the following formula (1), indicates the dispersibility of the particle size distribution of the spacer particles. A smaller SD value means a narrower dispersion, and a larger SD value means a wider dispersion. In this embodiment, the SD value is 3.0 to 10 μm, preferably 4.0 to 9.5 μm, and more preferably 5.0 to 9.0 μm. By keeping the SD value within the above range, the variation in size of the spacer particles is small, the dispersibility of the abrasive particles is improved, and there is less difference between areas that are easily abraded and areas that are difficult to abrade on the polishing surface, allowing the surface quality of the workpiece to be more stably maintained. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the cumulative value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.)

[0044] The d16% particle size is preferably 0.5 to 5.0 μm, more preferably 0.8 to 3.0 μm, and even more preferably 1.0 to 2.5 μm. The d84% particle size is preferably 5 to 30 μm, more preferably 8 to 25 μm, and even more preferably 10 to 20 μm.

[0045] The content of spacer particles having a particle diameter of 10 μm or less is preferably 50 to 85 mass %, more preferably 55 to 80 mass %, and even more preferably 60 to 75 mass %, relative to the total amount of spacer particles. By keeping the content of spacer particles having a particle diameter of 10 μm or less within the above range, the surface quality of the polished object tends to be more stably maintained.

[0046] The content of spacer particles having a particle diameter of 50 μm or more is preferably 1.0 to 3.0 mass %, more preferably 1.2 to 2.7 mass %, and even more preferably 1.3 to 2.5 mass %, relative to the total amount of spacer particles. By keeping the content of spacer particles having a particle diameter of 50 μm or more within the above range, the surface quality of the workpiece tends to be more stably maintained.

[0047] The content of the spacer particles is preferably 40 to 70 parts by mass, more preferably 45 to 65 parts by mass, and even more preferably 50 to 60 parts by mass, relative to 100 parts by mass of the polishing part. When the content of the spacer particles is within the above range, new abrasive particles can continue to appear due to the self-dressing property of the spacer particles, and the surface quality of the polished object tends to be more stably maintained.

[0048] The ratio of the spacer particle content to the abrasive 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 abrasive particle content is within the above range, the spacing between the abrasive particles becomes appropriate, the load on the abrasive particles is easily equalized, and the surface quality of the workpiece tends to be more stably maintained.

[0049] 1.2.4. Other auxiliary particles The other auxiliary particles are not particularly limited, but examples thereof include auxiliary particles having an average particle diameter D3 of 0.5 to 4.5 μm. By using such auxiliary particles, the surface quality of the polished object tends to be more stably maintained.

[0050] The components constituting such auxiliary particles are not particularly limited, but may include, for example, at least one selected from the group consisting of silicon dioxide and titanium oxide. By using auxiliary particles containing such components, the surface quality of the polished object tends to be more stably maintained, perhaps because it assists self-dressing. These auxiliary particles may be used alone or in combination of two or more types.

[0051] The average particle diameter D3 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 diameter D3 within the above range, the surface quality of the workpiece can be more stably maintained.

[0052] 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.

[0053] 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.

[0054] Anchor Layer The polishing pad of this embodiment may have an anchor layer between the substrate and the polishing part. By having an anchor layer, the adhesion between the substrate and the polishing part tends to be further improved.

[0055] The material for forming the anchor layer is not particularly limited, but may be, for example, a thermosetting resin coating agent.

[0056] 2. Manufacturing method of polishing pad The method for manufacturing a polishing pad of this embodiment includes an attachment step of attaching a curable composition containing a resin, abrasive particles, and spacer particles onto a substrate, and a curing step of curing the attached curable composition to obtain a polishing portion, wherein the average particle diameter D1 of the spacer particles is 3.5 to 15 μm, and the aspect ratio of the spacer particles (average major axis diameter / average minor axis diameter) is 2.0 to 12.

[0057] 2.1.Attachment process The adhering step is a step of adhering a curable composition containing a resin, abrasive particles, and spacer particles onto a substrate, and may be performed so that the abrasive portions form a desired uneven pattern.

[0058] 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.

[0059] In the screen printing method, for example, a plate with an opening pattern corresponding to the convex portions is prepared, and the plate is placed on a PET film serving as the base layer with gaps. The abrasive layer material is placed on the plate, and an appropriate pressure is applied to the squeegee, and the abrasive layer material is pressed against the openings of the plate while the squeegee is moved, thereby extruding and printing the abrasive layer material. The abrasive layer material is then hardened to obtain a polishing pad consisting of a patterned abrasive layer on the base 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 the PET film serving as the base layer via an adhesive. After this, the abrasive layer material is hardened by irradiating it with light from above the PET film, and the film is peeled off from the transfer mold, and if necessary, the convex portions are again irradiated with light to harden it, thereby obtaining a polishing pad consisting of a patterned abrasive layer on the base layer.

[0060] 2.1.1. Curable composition The curable composition is not particularly limited, but 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.

[0061] The polymerizable compound is not particularly limited, but examples thereof include (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

[0062] Examples of photopolymerization initiators include, but are not limited to, urethane resins, unsaturated polyester resins, alkyd resins, benzophenone compounds, acetophenone compounds, and thioxanthone compounds. Examples of thermal polymerization initiators include, but are not limited to, azo compounds such as 2,2'-azobisbutyronitrile, and peroxides such as benzoyl peroxide (BPO).

[0063] The thermosetting resin is not particularly limited, but examples thereof include phenol resin, epoxy resin, acrylic resin, urea resin, and formaldehyde resin.

[0064] 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.

[0065] 2.2.Curing process The curing step is a step of curing the adhered curable composition to obtain a polishing part. The curing method is not particularly limited, but examples thereof include photocuring and thermal curing. In the obtained polishing part, some of the abrasive particles and spacer particles are exposed on the surface, and the remaining abrasive particles and spacer particles are bonded in the resin.

[0066] 2.3.Other processes The method for producing a polishing pad of this embodiment may include other processes as needed. For example, after the adhesion process and before the curing process, a process of volatilizing and removing at least a portion of the volatile components in the curable composition may be included. Furthermore, after the adhesion process and before the curing process, and / or after the curing process, a process of removing a portion of the curable composition or the polishing portion may be included in order to form a desired uneven pattern. Examples of removal methods include cutting.

[0067] 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 a workpiece using the polishing pad in the presence of a coolant. The polishing step may be primary lapping (rough lapping), secondary lapping (finish lapping), or polishing, or may be a method combining two or more of these polishing steps.

[0068] The object to be polished is not particularly limited, but examples thereof include materials for semiconductor devices, electronic components, etc., particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaAs (gallium arsenide) substrates, glass, and substrates for hard disks and LCDs (liquid crystal displays). Among these, the method for manufacturing a polished product of this embodiment can be suitably used as a method for manufacturing glass as a material for magnetic disks such as hard disk drives, glass substrates used as the base material for reflective masks used in lithography using EUV light, and liquid crystal substrates and cover glasses for mobile terminals such as smartphones and tablets.

[0069] 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.

[0070] 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]

[0071] 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.

[0072] Example 1 (Preparation of Composite Particles) 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), 33 parts by weight of glass frit, and 14 parts by weight of diamond powder with an average particle size of 4 μm were mixed to prepare a slurry. The mixture was then spray-dried using a spray dryer to form a composite particle precursor. The composite particle precursor and white alumina (manufactured by Fujimi Co., Ltd., average particle size 3 μm) were then mixed in a ratio of 6:4 and calcined at 600 ° C for 4 hours to obtain composite particles with an average particle size of 40 μm.

[0073] (Preparation of spacer particles) Wollastonite C (K-400, manufactured by Keiwa Fine Materials Co., Ltd.) was pulverized in a ball mill at 390 rpm for 24 hours. The pulverized material was then sieved using a sieve with a predetermined particle size distribution to obtain wollastonite A having the average particle size, SD value, content of particles of 10 μm or less, and content of particles of 50 μm or more shown in Table 1. The sieve used can be, for example, a standard sieve specified in JIS Z8801, for sieving to a predetermined average particle size.

[0074] (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 part by mass of a photopolymerization initiator (Irgacure 819 manufactured by BASF Japan Ltd.), and 0.5 parts by mass of a photopolymerization initiator (Anthracure (registered trademark) UVS-581 manufactured by Kawasaki Chemical Industries, Ltd.).

[0075] Next, 7.2 parts by mass of the composite particles, 3.6 parts by mass of white alumina (manufactured by Fujimi Co., Ltd., average particle diameter 3 μm), 34.6 parts by mass of the precursor composition, and 54.6 parts by mass of the wollastonite A (average particle diameter 13.5 μm, aspect ratio 6) were mixed to prepare a curable composition.

[0076] (Preparation of polishing pads) The obtained curable composition was poured into a molding silicon intaglio plate having a rectangular prism-shaped recess with a depth of 2 mm, a cavity opening dimension of 2.6 mm × 2.6 mm, and a spacing of 1 mm between adjacent openings, and a PET substrate was placed so as to contact the upper surface of the curable composition. The curable composition was then cured by irradiating it with ultraviolet light using an ultraviolet irradiator. The obtained cured body (abrasive part) was then removed from the mold and heated in a dryer at 90 degrees for 12 hours to obtain the polishing pad of Example 1.

[0077] Example 2 Wollastonite C was pulverized in a ball mill at 250 rpm for 24 hours and sieved to obtain wollastonite B having the average particle size, SD value, content of particles of 10 μm or less, and content of particles of 50 μm or more as shown in Table 1. A polishing pad of Example 2 was obtained in the same manner as Example 1, except that wollastonite B was used instead of wollastonite A.

[0078] Comparative Example 1 A polishing pad of Comparative Example 1 was obtained in the same manner as in Example 1, except that wollastonite C was used instead of wollastonite A.

[0079] Comparative Example 2 Wollastonite (KF-6 manufactured by Keiwa Fine Materials) was pulverized in a ball mill at 250 rpm for 24 hours and sieved to obtain wollastonite D having the average particle size, SD value, content of particles of 10 μm or less, and content of particles of 50 μm or more as shown in Table 1. A polishing pad of Comparative Example 2 was obtained in the same manner as in Example 1, except that wollastonite D was used instead of wollastonite A.

[0080] Comparative Example 3 Wollastonite (KF-330 manufactured by Keiwa Fine Materials) was pulverized in a ball mill at 250 rpm for 24 hours and sieved to obtain wollastonite E having the average particle size, SD value, content of particles of 10 μm or less, and content of particles of 50 μm or more as shown in Table 1. A polishing pad of Comparative Example 3 was obtained in the same manner as in Example 1, except that wollastonite E was used instead of wollastonite A.

[0081] [Particle size distribution] The cumulative volumetric particle size distribution was measured using a Microtrac MT3300EXII laser diffraction particle size distribution analyzer manufactured by Microtrac-Bell Corporation, with a measurement time of 10 seconds. The particle size at which the cumulative value from the smallest diameter in the cumulative volumetric particle size distribution reached 50% of the total was defined as the average particle size. The particle size at which the cumulative value from the smallest diameter in the cumulative volumetric particle size distribution reached 16% of the total was defined as d16%, and the particle size (μm) at which the cumulative value from the smallest diameter in the cumulative volumetric particle size distribution reached 84% of the total was defined as d. The SD value was calculated using the following formula. The refractive index used during measurement was 1.61, and the refractive index of the medium (deionized water) was 1.333. Formula (1): SD value = (d84% - d16%) / 2

[0082] The wollastonite was photographed using a scanning electron microscope (JSM-5500LV, manufactured by JEOL Ltd.) Figures 3 to 5 show scanning electron microscope photographs of wollastonite A to C, and Figure 6 shows the measurement results of particle size distribution.

[0083] [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 Lubricant: Subrelve 9016 (Chemetall) 10-fold diluted aqueous solution Fluid volume: 30mL / min Grinding material: Glass (50mm x 50mm)

[0084] (surface roughness Ra of unpolished object) 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 Ra is 3 μm or more △: Glass surface roughness Ra is 1 μm or more and less than 3 μm ○: Glass surface roughness Ra is less than 1 μm

[0085] (Polishing rate stability) The polishing rate stability was evaluated based on the value calculated by dividing the polishing rate of the seventh batch by the polishing rate of the first batch, according to the following criteria. The polishing rate was evaluated as the thickness removed by polishing per hour, calculated from the polished amount calculated from the loss in the mass of the glass before and after polishing, the polished area of ​​the glass, and the specific gravity. The thickness was calculated from the polished amount calculated from the loss in the mass of the glass before and after processing, the polished area of ​​the glass, and the specific gravity. (Evaluation criteria) 〇: 40% or more △: 20% or more but less than 40% ×: Less than 20%

[0086] [Table 1]

[0087] As described above, the polishing pad of the present invention has a particle size distribution width (SD value) of the wollastonite spacer particles that is not too large, and the wollastonite has an appropriate particle size, so that the pad has appropriate disintegration properties, the unevenness is maintained during polishing, and a decrease in the polishing rate is suppressed. Furthermore, because the ratio of the average particle size D2 of the abrasive particles to the average particle size D1 of the wollastonite is appropriate, it has been shown that the pad has excellent abrasive particle retention and excellent surface roughness.

[0088] On the other hand, in Comparative Example 1, the distribution width (SD value) of the wollastonite particle size distribution was large, so that wollastonite particles of various sizes were exposed on the polishing surface, resulting in uneven ease of removal in each grinding area. Also, because the average particle size D2 of the abrasive particles was small compared to the average particle size D1 of the wollastonite, the abrasive particles fell off in a disorderly manner along with the fall-off of the wollastonite, resulting in large fluctuations in the polishing rate and a surface roughness inferior to that of the Examples.

[0089] In addition, in Comparative Example 2, although the distribution width (SD value) of the particle size distribution of the wollastonite was small, the average particle size of the wollastonite was also small, so the unevenness formed on the polished surface was small, and the unevenness at the beginning of polishing was clogged, resulting in a decrease in the polishing rate, a lack of polishing stability, and surface roughness inferior to that of the Examples.

[0090] Furthermore, in Comparative Example 3, although the distribution width (SD value) of the particle size distribution of the wollastonite was small, the average particle size of the wollastonite was large, so the wollastonite was easily detached during polishing, resulting in unevenness, increased wear, and ultimately a shortened product life. Also, because the average particle size D2 of the abrasive particles was small compared to the average particle size D1 of the wollastonite, abrasive particles also detached in a disordered manner along with the detachment of the wollastonite, resulting in large fluctuations in the polishing rate and surface roughness inferior to that of the Examples. [Industrial Applicability]

[0091] 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, and the like. [Explanation of symbols]

[0092] 10... polishing pad, 11... polishing portion, 12... substrate, 14... abrasive particles, 15... matrix

Claims

1. A substrate and an abrasive portion disposed on the substrate, the abrasive portion includes a resin, abrasive particles, and spacer particles; the average particle diameter D1 of the spacer particles is 3.5 to 15 μm; the SD value of the particle size distribution of the spacer particles, which is represented by the following formula (1), is 3.0 to 10 μm; the content of the spacer particles having a particle diameter of 10 μm or less is 50 to 80 mass % based on the total amount of the spacer particles; Polishing pad. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the integrated value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the integrated value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.)

2. The content of the spacer particles is 40 to 70 parts by mass relative to 100 parts by mass of the polishing part. The polishing pad of claim 1 .

3. the content of the spacer particles having a particle diameter of 50 μm or more is 1.0 to 3.0 mass% based on the total amount of the spacer particles; The polishing pad according to claim 1 or 2.

4. The spacer particles have a needle shape. The polishing pad according to any one of claims 1 to 3.

5. The content of the abrasive particles is 1.5 to 20 parts by mass relative to 100 parts by mass of the abrasive part. The polishing pad according to any one of claims 1 to 4.

6. The average particle diameter D2 of the abrasive particles is 10 to 100 μm. The polishing pad according to any one of claims 1 to 5.

7. the ratio (D2 / D1) of the average particle diameter D2 of the abrasive particles to the average particle diameter D1 of the spacer particles is 1.5 to 10; The polishing pad according to any one of claims 1 to 6.

8. The abrasive particles include composite particles containing abrasive particulates and matrix particles. The polishing pad according to any one of claims 1 to 7.

9. the matrix particles include glass frit; The polishing pad of claim 8.

10. the abrasive particles contain at least one selected from the group consisting of diamond, cerium oxide, silicon carbide, silicon oxide, zirconia, iron oxide, aluminum oxide, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, zirconium silicate, boron nitride, silicon nitride, barium carbonate, and calcium carbonate; The polishing pad according to any one of claims 1 to 9.

11. The polishing portion further contains auxiliary particles having an average particle diameter D3 of 0.5 to 4.5 μm. The polishing pad according to any one of claims 1 to 10.

12. a depositing step of depositing a curable composition containing a resin, abrasive particles, and spacer particles on a substrate; a curing step of curing the adhered curable composition to obtain a polished portion, the average particle diameter D1 of the spacer particles is 3.5 to 15 μm; the SD value of the particle size distribution of the spacer particles, which is represented by the following formula (1), is 3.0 to 1 μm; the content of the spacer particles having a particle diameter of 10 μm or less is 50 to 80 mass % based on the total amount of the spacer particles; A method for manufacturing a polishing pad. Formula (1): SD value = (d84% - d16%) / 2 (In formula (1), d16% represents the particle diameter (μm) when the integrated value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 16% of the total, and d84% represents the particle diameter (μm) when the integrated value from the smallest diameter in the cumulative distribution of particle diameters on a volume basis reaches 84% ​​of the total.)

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