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WO2025197434A1 - Tampon de polissage et son procédé de fabrication - Google Patents

Tampon de polissage et son procédé de fabrication

Info

Publication number
WO2025197434A1
WO2025197434A1 PCT/JP2025/006216 JP2025006216W WO2025197434A1 WO 2025197434 A1 WO2025197434 A1 WO 2025197434A1 JP 2025006216 W JP2025006216 W JP 2025006216W WO 2025197434 A1 WO2025197434 A1 WO 2025197434A1
Authority
WO
WIPO (PCT)
Prior art keywords
polishing
composite
particles
polishing pad
microparticles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/006216
Other languages
English (en)
Japanese (ja)
Inventor
堅一 小池
真治 岡田
亮介 東
恵介 中瀬
克樹 永井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujibo Holdings Inc
Original Assignee
Fujibo Holdings Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2024047182A external-priority patent/JP2025146423A/ja
Priority claimed from JP2024047196A external-priority patent/JP2025146434A/ja
Application filed by Fujibo Holdings Inc filed Critical Fujibo Holdings Inc
Publication of WO2025197434A1 publication Critical patent/WO2025197434A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting

Definitions

  • the present invention relates to a polishing pad and a method for manufacturing the same.
  • 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.
  • Patent Document 1 proposes a grinding tool that combines abrasive grains with dispersed grains that are softer than the abrasive grains in order to achieve both a high polishing rate and high flattening accuracy, and bonds the abrasive grains and dispersed grains in a dispersed state within a binder.
  • Patent Document 2 proposes an abrasive comprising a substrate sheet and an abrasive layer laminated on the surface side of the substrate sheet and containing diamond abrasive grains and a binder therefor, wherein the abrasive layer contains multiple types of abrasive grains, and among the multiple types of abrasive grains, the abrasive grains with the largest average particle diameter are designated as first abrasive grains and the abrasive grains with the second largest average particle diameter are designated as second abrasive grains, and the ratio of the average particle diameter of the second abrasive grains to the average particle diameter of the first abrasive grains is 5% to 70%.
  • This abrasive is disclosed as a technology in which alumina abrasive grains, which are smaller in size than the diamond abrasive grains, are overgrown from the abrasive layer before the diamond abrasive grains, causing a portion of the abrasive layer to fall off moderately, thereby causing the diamond abrasive grains with a relatively reduced grinding force to be overgrown, exposing new abrasive grains and preventing a decrease in the polishing rate due to excessive grain overgrown.
  • Patent Document 1 proposes a grinding tool comprising diamond abrasive grains, a binder, and dispersed grains that are harder than the binder but softer than the diamond abrasive grains, with the diamond abrasive grains and dispersed grains dispersed and bonded within the binder.
  • This grinding tool disperses abrasive grains made of a material softer than the diamond abrasive grains and their aggregates (dispersed grains) together with diamond abrasive grains formed by solidifying multiple diamond abrasive grains with glass, thereby uniformly increasing the distance between the diamond abrasive grains and increasing the machining speed.
  • the presence of the dispersed grains prevents excessive pressure from concentrating on the diamond abrasive grains, thereby suppressing tool wear.
  • the grinding tool described in Patent Document 1 uses dispersed particles that are softer than grinding abrasive grains, and particles of different strengths are unevenly present on the grinding tool surface. This causes variations in the way the surface is ground during the dressing process performed for surface finishing or removing clogging, resulting in deterioration of the polishing characteristics. Therefore, there is still room for improvement in order to maintain the polishing rate and flattening accuracy even after dressing.
  • the present invention was made in consideration of the above problems, and its primary objective is to provide a polishing pad and a manufacturing method thereof that can produce polished objects with low surface roughness while maintaining a stable polishing rate.
  • Patent Document 1 uses dispersed particles that are softer than grinding abrasive grains, and particles of different strengths are unevenly present on the grinding tool surface. This causes variations in the way the surface is ground during the dressing process performed for surface finishing or removing clogging, resulting in deterioration of the polishing characteristics. Therefore, there is still room for improvement in order to maintain the polishing rate and flattening accuracy even after dressing.
  • the present invention was made in consideration of the above problems, and its second object is 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.
  • the abrasive described in Patent Document 2 even if it can maintain the polishing rate, has low gripping strength for diamond abrasive grains, and small diamond abrasive grains with a particle size of around 10 ⁇ m tend to fall off. As a result, the number of diamond abrasive grains gripped on the polishing surface decreases, the polishing rate decreases, the polishing surface becomes rough, and the surface roughness of the polished object cannot be reduced.
  • the grinding tool described in Patent Document 1 uses concentrated abrasive grains, which makes the diamond abrasive grains less likely to fall off, but the mixture of dispersed grains and concentrated abrasive grains results in particles of different strengths being unevenly present on the grinding tool surface, which causes variations in the way the surface is ground during the dressing process performed during surface finishing and clogging removal, resulting in poor polishing characteristics. Therefore, there is still room for improvement in suppressing the decrease in polishing rate and achieving both maintaining the polishing rate and reducing the surface roughness of the polished object.
  • the present invention was made in consideration of the above problems, and its third object is to provide a polishing pad and a manufacturing method thereof that has improved self-dressing properties, can maintain a stable polishing rate, and can produce polished objects with low surface roughness.
  • the inventors discovered that the first problem could be solved by adjusting the ratio (Da/Dd) of the average particle diameter (Da) of the composite microparticles to the average particle diameter (Dd) of the diamond abrasive grains in the polishing area having convex portions, and the proportion of diamond abrasive grains to the convex portions, thereby completing the present invention.
  • the present invention includes the following aspects.
  • the composite microparticles include diamond abrasive grains, The ratio (Da/Dd) of the average particle diameter (Da) of the composite microparticles to the average particle diameter (Dd) of the diamond abrasive grains is 8.0 to 20.0;
  • the content of the diamond abrasive grains is 0.50 to 2.00 mass% with respect to the total amount of the convex portions.
  • Polishing pad [2]
  • the area of the polishing surface of one independent convex portion among the convex portions is 4.0 to 49.0 mm2 .
  • the content of the composite fine particles is 20 to 200 particles/ mm2 relative to the area of the polished surface of the convex portion;
  • the content of the diamond abrasive grains is 3.0 to 20.0 mass% with respect to the total amount of the composite fine particles.
  • the average particle diameter (Da) of the composite fine particles is 30.0 to 100.0 ⁇ m.
  • the average particle diameter (Dd) of the diamond abrasive grains is 1.5 to 12.5 ⁇ m.
  • [1] - [5] The polishing pad according to any one of the above. [7] the ratio of the total area of the polishing surfaces of the convex portions to the area of the polishing portions is 50.0 to 80.0 area %; [1] The polishing pad according to any one of [1] to [6]. [8] 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 having convex portions, The content of the diamond abrasive grains is 0.50 to 2.00 mass% with respect to the total amount of the convex portions.
  • a method for manufacturing a polishing pad [9] [1] to [7], comprising a step of polishing an object to be polished using the polishing pad according to any one of [1] to [7]. Manufacturing method for polished products.
  • the inventors discovered that the second problem could be solved by using composite microparticles with a specified crushing strength, leading to the completion of the present invention.
  • the present invention includes the following aspects.
  • the composite microparticles include diamond abrasive grains,
  • the crushing strength (Cs) of the composite microparticles is 100.0 to 300.0 MPa.
  • 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 standard deviation (SD) of the crushing strength of the composite microparticles is 15.0 to 170.0 MPa.
  • the polishing portion has a convex portion.
  • the inventors discovered that the third problem could be solved by using a specified amount of hollow composite microparticles, leading to the completion of the present invention.
  • the present invention includes the following aspects.
  • 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 composite particles include hollow composite particles,
  • the content of the hollow composite fine particles is 5 to 40 mass% based on the total amount of the composite fine particles.
  • the composite particulates further comprise solid composite particulates; the difference between the crushing strength (Cs 1 ) of the hollow composite particles and the crushing strength (Cs 2 ) of the solid composite particles is 40.0 to 100.0 MPa;
  • the hollow composite fine particles have an average particle size of 20 to 100 ⁇ m.
  • the thickness of the shell of the hollow composite fine particles is 5 to 35 ⁇ m.
  • the average particle size of the diamond abrasive grains is 3 to 9 ⁇ m.
  • the polishing portion has a convex portion.
  • FIG. 1 is a perspective view showing polishing pads according to a first embodiment, a second embodiment, and a third embodiment.
  • 1 is an enlarged cross-sectional view showing polishing pads according to a first embodiment, a second embodiment, and a third embodiment.
  • 1 is an electron microscope photograph of a cross section of hollow composite fine particles.
  • the present embodiments in the order of ⁇ First Embodiment>, ⁇ Second Embodiment>, and ⁇ Third Embodiment>, but the present invention is not limited to these and various modifications are possible without departing from the spirit of the present invention.
  • polishing Pad A polishing pad according to a first embodiment comprises a substrate and a polishing portion disposed on the substrate, the polishing portion having protruding portions, the polishing portion including a resin and composite microparticles, the composite microparticles including diamond abrasive grains, the ratio (Da/Dd) of the average particle diameter (Da) of the composite microparticles to the average particle diameter (Dd) of the diamond abrasive grains being 8.0 to 20.0, and the content of the diamond abrasive grains being 0.50 to 2.00 mass% relative to the total amount of the protruding portions.
  • FIG. 1 shows a schematic perspective view of a polishing pad according to a first embodiment.
  • this polishing pad 10 comprises a substrate 11 and a polishing portion 12 disposed on the substrate 11.
  • a plurality of convex portions 13 formed by the polishing portion 12 are arranged on the surface of the substrate 11, forming an uneven pattern.
  • the abrasive portions 12 may have protruding portions 13, and may be an uneven pattern in which protruding portions are arranged, a pattern (negative pattern) in which abrasive portions 12 are formed by punching out a uniform layer in the form of dots, or any other pattern with protruding portions.
  • the presence of protruding portions increases the pressure exerted on each protruding portion when polishing the object to be polished, and the small amount of abrasive particles contained in the protruding portions can improve the polishing rate while also reducing the surface roughness of the object to be polished.
  • Figure 2 shows a schematic cross-sectional view of a polishing pad according to the first embodiment.
  • the polishing portion 12 of the polishing pad 10 according to the first embodiment contains composite microparticles 14 and resin 15.
  • the polishing portion 12 also has convex portions 13, which contain a predetermined amount of diamond abrasive grains. This improves the polishing rate through the polishing action of the diamond abrasive grains, while suppressing scratches on the workpiece caused by excess diamond abrasive grains and reducing the surface roughness of the workpiece.
  • the polishing surface of the polishing portion 12 (which is also the polishing surface of the convex portions 13) is gradually worn away, forming a new polishing surface in which the composite microparticles 14 embedded in the polishing portion 12 are exposed, which tends to maintain the polishing rate.
  • the polishing portion 12 has a polishing surface 17.
  • the polishing surface 17 is the upper bottom surface of the convex portion 13 in the polishing portion 12, and is the portion that comes into contact with the workpiece to be polished.
  • the portion that comes into contact with the workpiece to be polished is the polishing surface 17 of the convex portion.
  • Substrate 11 is a member on which the polishing portion 12 is formed, and may be attached to the polishing device via an adhesive layer, which will be described later.
  • the substrate is not particularly limited, but examples include polyester-based sheets such as polyethylene terephthalate sheets, polypropylene terephthalate sheets, and polybutylene terephthalate sheets; polyolefin-based 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.
  • PET-based sheets such as polyethylene terephthalate sheets, polypropylene terephthalate sheets, and polybutylene terephthalate sheets
  • polyolefin-based sheets such as polyethylene (PE) sheets, polypropylene (PP) sheets, and ethylene-propylene copolymer sheets
  • PEEK polyether ether ketone
  • PPS polyphenylene sulfide
  • acrylic sheets are preferred from the standpoints of rigidity, adhesion, and processability.
  • the abrasive section may have a convex portion, and may be formed alone or together with a substrate to form a concave-convex pattern (see Figures 1 and 2).
  • the abrasive section 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.
  • the abrasive section also contains a resin and composite particles, and may contain other spacer particles as needed.
  • the polishing section to have an uneven pattern, and more preferably to have a regular uneven pattern. Having a regular pattern makes uniform polishing possible, and polishing with excellent surface quality can be achieved.
  • a regular pattern refers to a pattern obtained by arranging multiple small unit patterns. The surface of the polishing section opposite the substrate serves as the polishing surface for polishing the workpiece.
  • the uneven 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 formed independently on the substrate 11 as shown in FIG.
  • a negative pattern (a pattern with dot-shaped concave portions) in which the abrasive portions are formed continuously 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.
  • a pattern with dot-shaped convex portions is preferred. Having such an uneven pattern tends to further improve the ability to remove abrasive debris.
  • the three-dimensional shape of the dots is not particularly limited, and examples include hemisphere, approximately hemisphere, spherical cap, approximately spherical cap, spherical band, approximately spherical band, semi-ellipsoid, approximately semi-ellipsoid, columnar (cylindrical, approximately cylindrical, elliptical cylinder, approximately elliptical cylinder, polygonal columnar), and frustum (circular frustum, approximately circular frustum, elliptical frustum, approximately elliptical frustum, polygonal frustum).
  • the frustum may be a frustum that widens from the substrate side toward the polishing surface side, or a frustum that widens from the polishing surface side toward the substrate side.
  • the three-dimensional shape of the space in the recesses can be similar to the three-dimensional shape in the case of a pattern having dot-shaped protrusions.
  • the polishing surface area of one independent convex portion is not particularly limited, but is preferably 4.0 to 49.0 mm 2 , more preferably 6.0 to 36.0 mm 2 , and even more preferably 9.0 to 25.0 mm 2.
  • the polishing surface area of one independent convex portion is within the above range, the abrasion properties of the resin and composite fine particles in the polishing part become appropriate, new diamond abrasive grains become more easily exposed, and this contributes to stabilizing the polishing rate.
  • the proportion of the total area of the polishing surface of the convex portions is not particularly limited, but is preferably 50.0 to 80.0 area% relative to the area of the polishing portion, more preferably 50.0 to 70.0 area%, and even more preferably 50.0 to 60.0 area%.
  • the proportion of the total area of the polishing surface of the convex portions within the above range, the composite microparticles can be dispersed approximately uniformly within the polishing surface, and when polishing the workpiece, the pressure applied to each convex portion increases, thereby improving the polishing rate with a small amount of polishing microparticles while also reducing the surface roughness of the workpiece.
  • the "area of the polishing portion” refers to the area of the polishing portion when viewed in plan.
  • 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, al
  • acrylic resins polyurethane resins, unsaturated polyester resins, and phenol-modified alkyd resins are preferred, with three-dimensionally cross-linked acrylic resins being even more preferred.
  • the use of such resins tends to further improve the polishing rate.
  • the resins that make up the polishing portion may be used alone or in combination of two or more types.
  • the composite microparticles contain diamond abrasive grains as abrasive microparticles, which are components that contribute to polishing.
  • the composite microparticles may also contain matrix particles. They may also contain other abrasive microparticles, auxiliary particles, etc.
  • 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 conveniently referred to as "matrix particles.”
  • the matrix particles are fused to each other and do not necessarily have to be particles.
  • the abrasive microparticles may be dispersed in the fused matrix particles.
  • the auxiliary particles may be particles added to suppress blocking between the composite microparticles.
  • the composite microparticles contain diamond abrasive grains and matrix particles. This increases the polishing efficiency because new abrasive microparticles are exposed from the inside as the matrix particles wear down.
  • the average particle diameter (Da) of the composite microparticles can be adjusted by the nozzle diameter, drying temperature, and spray pressure of the spray dryer, and is preferably 30.0 to 100.0 ⁇ m, more preferably 30.0 to 90.0 ⁇ m, and even more preferably 30.0 to 80.0 ⁇ m.
  • the composite microparticles are less likely to detach from the polishing pad, maintaining a more stable polishing rate, while also tending to reduce the surface roughness of the resulting polished object.
  • average particle size refers to the particle size at which the cumulative particle volume is 50% of the total in a particle size distribution graph with particle size on the horizontal axis and cumulative particle volume percentage on the vertical axis. This average particle size is also called the median diameter or d50. Particle size distribution graphs can be obtained using laser diffraction scattering methods, etc.
  • the content of the composite microparticles is preferably 1.50 to 40.0 mass% relative to the total amount of the polishing portion, more preferably 5.00 to 35.0 mass%, and even more preferably 8.00 to 30.0 mass%.
  • the polishing rate tends to be further improved.
  • the content of the composite microparticles is 40.0 mass% or less, the grinding force tends to be further improved.
  • the content of the composite microparticles relative to the area of the polishing surface of the convex portions is preferably 20 to 200 particles/ mm2 , more preferably 20 to 180 particles/ mm2 , and even more preferably 20 to 160 particles/ mm2 .
  • the content of the composite microparticles is 20 particles/mm2 or more, the load at the contact point with the workpiece is not concentrated too much, thereby suppressing deep scratches on the workpiece.
  • the content is 200 particles/ mm2 or less , the load at the contact point with the workpiece is not dispersed too much, thereby improving the polishing rate.
  • the content of the composite microparticles relative to the area of the polishing surface of the convex portions can be calculated, for example, by the following method.
  • the polishing surface of the convex portions of the polishing pad is observed using a scanning transmission electron microscope (STEM), and the number of composite microparticles is measured and calculated from the elemental mapping results obtained by EDS analysis using image processing software ImageJ.
  • 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 component with the highest grinding ability.
  • 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.
  • diamond abrasive grains have the best grinding ability. These abrasive grains can be used alone or in combination of two or more types.
  • the average particle size of the abrasive particles varies depending on the workpiece and process, but is preferably 1.0 to 11.0 ⁇ m, more preferably 2.0 to 10.5 ⁇ m, and even more preferably 3.0 to 10.0 ⁇ m. By keeping the average particle size within the above range, it is possible to prevent the abrasive particles from causing deep scratches on the workpiece.
  • the average particle diameter (Dd) of the diamond abrasive grains varies depending on the workpiece and process, but is preferably 1.5 to 12.5 ⁇ m, more preferably 2.0 to 11.0 ⁇ m, and even more preferably 3.0 to 10.0 ⁇ m. By keeping the average particle diameter (Dd) within the above range, it is possible to prevent the abrasive particles from causing deep scratches in the workpiece.
  • the ratio (Da/Dd) of the average particle size (Da) of the composite microparticles to the average particle size (Dd) of the diamond abrasive grains is preferably 8.0 to 20.0, more preferably 8.0 to 18.0, and even more preferably 8.5 to 16.0.
  • Da/Dd is 8.0 or greater
  • the diamond abrasive grains are fixed within the composite microparticles during production, allowing multiple diamond abrasive grains to be contained, and there is a tendency for the polishing rate to be maintained more stably.
  • Da/Dd is 20.0 or less, the diamond abrasive grains are more likely to be exposed on the surface of the composite microparticles, and there is a tendency for the grinding force of the composite microparticles to be maintained.
  • the diamond abrasive grain content is preferably 3.0 to 20.0 mass% of the total amount of composite microparticles, more preferably 4.0 to 18.0 mass%, and even more preferably 5.0 to 15.0 mass%.
  • the diamond abrasive grain content is preferably 0.50 to 1.50 mass% of the total amount of convex portions, more preferably 0.60 to 1.45 mass%, and even more preferably 0.70 to 1.40 mass%.
  • 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.
  • silicon dioxide, boron oxide, and zinc oxide are preferred. It is more preferable to use glass frit obtained by melting and molding a glass material primarily composed of silicon dioxide, boron oxide, and zinc oxide, followed by powdering.
  • matrix particles results in composite particles strong enough to hold abrasive particles without shattering the composite 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.
  • matrix particles may be used alone or in combination of two or more types.
  • the average particle size of the powdered matrix particles is preferably 1.0 to 20 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10 ⁇ m. It is preferable for the average particle size to be about the same as the abrasive particles, as this tends to result in a uniform distribution within the composite particles and reduces variation in grinding ability between composite particles.
  • the ratio of the average particle size of the matrix particles to the average particle size of the composite microparticles is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20.
  • the matrix particle content is preferably 10.0 to 90.0 mass% of the total amount of composite microparticles, more preferably 20.0 to 75.0 mass%, and even more preferably 30.0 to 60.0 mass%.
  • the spacing between the abrasive microparticles increases, there is less contact between the abrasive microparticles and the workpiece during polishing, the load per abrasive microparticle increases, the grinding force increases, and the polishing rate tends to improve.
  • the matrix particle content is preferably 1.0 to 20.0 mass% of the total amount of the convex portions, more preferably 2.0 to 17.0 mass%, and even more preferably 3.0 to 14.0 mass%.
  • the spacing between the abrasive particles increases, there is less contact between the abrasive particles and the workpiece during the polishing process, the load per abrasive particle increases, the grinding force increases, and the polishing rate tends to improve.
  • auxiliary particles are not particularly limited, but examples thereof include auxiliary particles having an average particle diameter of 0.5 to 4.5 ⁇ m. By using such auxiliary particles, blocking of the composite fine particles is suppressed, and the polishing rate tends to improve.
  • the auxiliary particles may be located on the surface of the composite fine particles.
  • auxiliary particles are not particularly limited, but examples include 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.
  • white alumina abrasive grains brown alumina abrasive grains
  • black silicon carbide abrasive grains green silicon carbide abrasive grains
  • barium sulfate cerium oxide
  • auxiliary particles may be used alone or in combination of two or more types.
  • the average particle size of the auxiliary particles is preferably 0.5 to 4.5 ⁇ m, more preferably 0.7 to 4.0 ⁇ m, and even more preferably 0.9 to 3.5 ⁇ m. By keeping the average particle size within this range, blocking of the composite microparticles can be effectively suppressed, making it easier to achieve an improved polishing rate and further reducing the surface roughness of the resulting polished object.
  • the content of auxiliary particles is preferably 35.0 to 65.0 mass% of the total amount of composite microparticles, more preferably 40.0 to 60.0 mass%, and even more preferably 45.0 to 55.0 mass%.
  • auxiliary particles is preferably 1.0 to 20.0 mass% relative to the total amount of convex portions, more preferably 2.0 to 17.0 mass%, and even more preferably 3.0 to 14.0 mass%.
  • 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.
  • 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).
  • 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
  • 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 further reduced.
  • the average particle size of the spacer particles is 5.0 to 20 ⁇ m, preferably 7.5 to 17.5 ⁇ m, and more preferably 10 to 15 ⁇ m.
  • the average particle size of the spacer particles in the polishing pad can be measured by known methods. For example, the polishing pad is heated to 550°C or the like, the sample is ashed, and the roughly spherical composite microparticles are removed to extract the spacer particles from the polishing pad, which are then thoroughly dispersed using an ultrasonic disperser or the like to prepare a dispersion. Using this dispersion, the average particle size of the spacer particles can be measured from the particle size distribution measured using a laser diffraction/scattering particle size distribution analyzer.
  • the ratio of the average particle size of the composite microparticles 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.
  • the ratio is 1.5 or higher, the spacer particles can be packed densely around the composite abrasive grains, making it easier to fix the composite microparticles.
  • the ratio is 10 or lower, the grinding force can be increased without the spacer particles being pressed into the polishing pad during polishing. By keeping the ratio within the above range, the surface quality of the workpiece can be more stably maintained.
  • the aspect ratio (average major axis diameter/average minor axis diameter) of the spacer particles is 2.0 to 12, preferably 2.5 to 10, and more preferably 3.0 to 7.0. Having an aspect ratio (average major axis diameter/average minor axis diameter) within the above range provides adequate self-dressing properties, allows the polishing rate to be maintained more stably, and reduces the surface roughness of the resulting polished object. There are no particular restrictions on the method for measuring the aspect ratio of the spacer particles, but it can be calculated from photographs taken with an electron microscope.
  • the content of spacer particles is preferably 20 to 70 mass% of the total amount of the polishing portion, more preferably 25 to 65 mass%, and even more preferably 30 to 60 mass%. By keeping the content of spacer particles within this range, the self-dressing properties of the spacer particles allow new composite microparticles to continue to appear, making the polishing rate more stable and tending to further reduce the surface roughness of the polished object.
  • the ratio of the spacer particle content to the composite microparticle content is preferably 1.0 to 7.0, more preferably 1.1 to 6.5, and even more preferably 1.3 to 6.0.
  • the ratio of the spacer particle content to the composite microparticle content is within the above range, the spacing between the composite microparticles becomes appropriate, the load on the composite microparticles is more evenly distributed, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the polishing pad of the first 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.
  • 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, and silicone adhesives.
  • the adhesive layer may also be, for example, double-sided tape.
  • the manufacturing method of the polishing pad of the first embodiment includes a firing step of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles, and a curing step of curing a curable composition containing a resin and the composite microparticles to obtain a polishing part having convex portions, wherein the content of the diamond abrasive grains is 0.50 to 2.00 mass% relative to the total amount of the convex portions.
  • the firing process is a process of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles.
  • the firing process may include a composite microparticle precursor preparation process containing diamond abrasive grains and matrix particles.
  • the composite microparticle precursor obtained by the composite microparticle precursor preparation process described below is fired to thermally decompose the binder resin in the composite microparticle precursor, causing the matrix particles to fuse together and bond appropriately.
  • the aforementioned auxiliary particles may also be included and fired.
  • the auxiliary particles blocking between the composite microparticle precursors can be suppressed.
  • the firing temperature in the firing step is preferably above the yield point of the matrix particles. If the firing temperature is above the yield point of the matrix particles, the matrix particles tend to fuse together and bond appropriately, further improving the stability of the composite microparticles. If the firing temperature is too low, the matrix particles will not bond together, reducing the strength of the composite microparticles and resulting in inferior polishing performance when used in a polishing pad.
  • the firing temperature is preferably the yield point of the matrix particles + 150°C or less, more preferably the yield point of the matrix particles + 120°C or less, even more preferably the yield point of the matrix particles + 100°C or less, and even more preferably the yield point of the matrix particles + 80°C or less.
  • the lower limit of the firing temperature is preferably equal to or higher than the yield point of the matrix particles. If the firing temperature is equal to or lower than the yield point of the matrix particles + 150°C, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention force of the composite particles can be kept within a suitable range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other and will need to be crushed after firing, which may result in distorted shapes of the composite particles and impair the abrasive grain retention force of the composite particles.
  • the firing temperature depends on the yield point of the 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 to 630°C. If the firing temperature is within the above range, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention power of the composite particles can be kept within an appropriate range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other, requiring them to be crushed after firing, which can result in distorted shapes of the composite particles and may impair the composite particles' ability to retain the abrasive grains.
  • the firing time in the firing step is, for example, 0.5 to 30 hours. This may be adjusted as appropriate to obtain the desired composite microparticles.
  • the atmosphere during the firing process is not particularly limited, but air is preferred.
  • the atmosphere during the firing process is not particularly limited, but an open system is preferable.
  • 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.
  • the binder resin is preferably a resin that can bind the diamond abrasive grains and matrix particles and can be thermally decomposed by the firing process described below.
  • Water-soluble resins are more preferred, and resins commonly used as binders can be used. Examples include dextrin, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, and polyacrylamide, with dextrin being preferred. These binder resins may be used alone or in combination of two or more.
  • Dispersants are not particularly limited, but examples include quaternary ammonium salts, polycarboxylic acid surfactants, and maleic anhydride surfactants.
  • Solvents include, for example, water and alcohols such as methanol and isopropanol, with water being preferred. These solvents may be used alone or in combination of two or more.
  • additives may be blended into the composite microparticle precursor composition.
  • examples of other additives include deflocculants (dispersants) and surfactants. These additives may be used alone or in combination of two or more.
  • the method for granulating the composite microparticle precursor composition is not particularly limited, but examples include a method using a spray dryer or other spray dryer. In this method, the precursor composition is sprayed into heated air and the solvent (dispersion liquid) is evaporated to obtain precursor particles.
  • the granulation conditions are not particularly limited and can be set appropriately 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; for example, if water is used as the solvent, it may be 150 to 250°C.
  • the curing step is a step of obtaining a polishing part by curing a curable composition containing a resin and composite fine particles.
  • the curable composition is not particularly limited as long as it contains a resin and composite particles, but examples include photocurable compositions containing a photopolymerization initiator and a polymerizable compound; thermosetting compositions containing a thermal polymerization initiator and a polymerizable compound; UV-curable resins; and curable compositions containing two-component mixed curable resins. Furthermore, the curable composition may optionally contain a crosslinker having two or more polymerizable functional groups.
  • the polymerizable compound is not particularly limited, but examples include (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.
  • Photopolymerization initiators are not particularly limited, but examples include phosphine oxide compounds, benzophenone compounds, acetophenone compounds, and thioxanthone compounds. Furthermore, thermal polymerization initiators are not particularly limited, but examples include azo compounds such as 2,2'-azobisbutyronitrile, and peroxides such as benzoyl peroxide (BPO).
  • Thermosetting resins are not particularly limited, but examples include urethane resins, unsaturated polyester resins, alkyd resins, phenolic resins, epoxy resins, acrylic resins, urea resins, and formaldehyde resins.
  • UV-curable resin there are no particular limitations on the UV-curable resin, but for example, a prepolymer with a number-average molecular weight of approximately 1,000 to 10,000 is suitable.
  • materials include acrylic (methacrylic) esters, their urethane modifications, and thiokol-based materials. Reactive diluents and organic solvents can be used as appropriate depending on the application.
  • prepolymers with different physical properties can be used.
  • the curable composition may contain components other than the resin, composite microparticles, and polymerization initiator.
  • Such components include, for example, the fillers and auxiliary particles described above.
  • the curing method of 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.
  • 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.
  • the polishing part and the substrate may be bonded by applying the curable composition to the substrate and curing the curable composition.
  • the surface of the polishing part opposite the polishing surface, which has been cured in advance may be bonded to the substrate via an adhesive.
  • the method for applying the curable composition to the substrate is not particularly limited, but examples include gravure coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, die coater method, screen printing method, spray coating method, embossing roll method, and transfer method. Of these, screen printing method or transfer method is preferred from the standpoint of ease of forming complex concave-convex patterns and productivity.
  • a plate with an opening pattern corresponding to the protrusions is prepared, gaps are formed on a PET sheet that serves as the base layer, the plate is then placed, the abrasive layer material is placed on the plate, and moderate pressure is applied to the squeegee, which moves while pressing the abrasive layer material into the openings in the plate, 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.
  • transfer printing for example, a transfer mold with recesses corresponding to the protrusions is prepared, and the abrasive layer material is filled into this mold.
  • the filled abrasive layer material is then bonded to a base material such as a PET sheet or acrylic sheet that serves as the base layer via an adhesive.
  • the abrasive layer material is then hardened 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 protrusions are irradiated with light again to harden it, resulting in a polishing pad consisting of a patterned abrasive layer on the base layer.
  • the method may further include a step of bonding the substrate on which the abrasive portion is disposed to another substrate.
  • the surface of the substrate opposite the surface on which the abrasive portion is disposed is bonded to the other substrate via an adhesive.
  • the type of adhesive used is not particularly limited, and may be liquid, double-sided tape, or adhesive tape made from an adhesive processed into a tape-like form. Examples of liquid adhesives include curing adhesives such as photocuring resins, thermosetting resins, and moisture-curing resins, solvent-volatile adhesives, and hot-melt adhesives.
  • the adhesive can be applied using any conventional method known in the art. Examples include printing, such as screen printing, spray application, and application with a roller or brush.
  • the type of adhesive used to bond the surface opposite the abrasive surface of the pre-cured abrasive portion to the substrate is not particularly limited, and any of the adhesives listed above may be used as appropriate.
  • the method for producing a polishing pad of the first embodiment may include other steps, if necessary. For example, it may include a step of volatilizing and removing at least a portion of the volatile components in the curable composition before the curing step. Furthermore, it may include a step of removing a portion of the curable composition or the polishing portion before and/or after the curing step to form a desired uneven pattern. Examples of the removal method include cutting.
  • the manufacturing method of the polished product of the first 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.
  • a coolant may also be used in the polishing.
  • the workpiece to be polished is not particularly limited, but examples include materials for semiconductor devices, electronic components, and the like, particularly thin substrates (workpieces to be polished) 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).
  • Si substrates silicon wafers
  • SiC silicon carbide
  • GaN gallium nitride
  • GaAs gallium arsenide
  • sapphire substrates glass
  • glass substrates for hard disks and LCDs (liquid crystal displays).
  • the method for manufacturing a polished product of the first embodiment is particularly suitable for manufacturing magnetic disks such as hard disk drives, glass substrates used as the base material for reflective masks used in lithography using EUV light, glass used as the material for LCD substrates and cover glass for mobile devices 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.
  • SiC silicon carbide
  • GaN gallium nitride
  • GaAs gallium arsenide
  • 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 a conventionally known method and is not particularly limited.
  • a polishing pad is attached to a predetermined position on the polishing device. During this attachment, the polishing pad is attached so that it is fixed to the polishing device via the adhesive layer described above. Then, the workpiece to be polished is held on a holding platen positioned opposite the polishing pad, which serves as a polishing platen, and pressed against the polishing surface. Coolant is supplied from outside while the polishing pad and/or holding platen are rotated. This allows the coolant supplied between the polishing pad and the workpiece to act to reduce polishing resistance and remove polishing debris, while polishing the workpiece surface (surface to be polished).
  • polishing Pad A polishing pad according to a second embodiment includes a substrate and a polishing portion disposed on the substrate, the polishing portion including a resin and composite particles, the composite particles including diamond abrasive grains, and the crushing strength of the composite particles is 100.0 to 300.0 MPa.
  • FIG. 1 shows a schematic perspective view of a polishing pad according to a second embodiment.
  • this polishing pad 10 comprises a substrate 11 and a polishing portion 12 disposed on the substrate 11.
  • a plurality of convex portions formed by the polishing portion 12 are arranged on the surface of the substrate 11, forming an uneven pattern.
  • the polishing portion 12 may form a concave-convex pattern together with the substrate 11 as shown in Figure 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 12 formed by punching out dots from a uniform layer, or any other pattern.
  • FIG. 2 shows a schematic cross-sectional view of a polishing pad according to a second embodiment.
  • the polishing portion 12 of the polishing pad 10 according to the second embodiment contains composite microparticles 14 and resin 15.
  • the polishing portion 12 can suppress a decrease in the polishing rate due to the diamond abrasive grains contained in the composite microparticles 14 easily detaching from the composite microparticles 14, as well as scratches caused by the free diamond abrasive grains rolling around.
  • the composite microparticles 14 have a predetermined crushing strength, scratches caused by the diamond abrasive grains being firmly fixed are suppressed.
  • the polishing surface of the polishing portion 12 is gradually worn away, and a new polishing surface is formed where the composite microparticles 14 that were embedded in the polishing portion 12 are exposed, which tends to maintain the polishing rate.
  • the substrate is a member on which the polishing portion is formed, and may be attached to the polishing device via an adhesive layer, which will be described later.
  • the substrate is not particularly limited, but examples include those described in the first embodiment. Among these, polyester sheets are preferred from the standpoints of chemical resistance, heat resistance, and economy, while acrylic sheets are preferred from the standpoints of rigidity, adhesiveness, and processability.
  • the abrasive section contains a resin and composite particles, and may contain other spacer particles as needed.
  • the abrasive section 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).
  • the abrasive section 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.
  • the polishing section to have an uneven pattern, and more preferably to have a regular uneven pattern. Having a regular pattern makes it possible to perform uniform polishing and achieve polishing with excellent surface quality. Furthermore, the surface of the polishing section opposite the substrate becomes the polishing surface for polishing the workpiece.
  • the uneven pattern is not particularly limited as long as it has portions that come into contact with the workpiece (convex portions) and portions that do not come into contact with the workpiece (concave portions).
  • Examples include a positive pattern (a pattern with dot-shaped convex portions) in which the polishing portions 12 are independently formed on the substrate 11 as shown in Figure 1, as well as the uneven pattern described in the first embodiment. Of these, a pattern with dot-shaped convex portions is preferred. Having such an uneven pattern tends to further improve the ability to remove polishing debris.
  • the three-dimensional shape of the dots is not particularly limited, and examples include the shapes described in the first embodiment.
  • the frustum shape may be a frustum shape that widens from the substrate side toward the polishing surface side, or a frustum shape that widens from the polishing surface side toward the substrate side.
  • the three-dimensional shape of the space in the recesses can be exemplified as being similar to the three-dimensional shape in the case of a pattern having dot-shaped protrusions.
  • the resin is not particularly limited, but is preferably a thermosetting resin or a photocurable resin, such as those described in the first embodiment.
  • acrylic resins polyurethane resins, unsaturated polyester resins, and phenol-modified alkyd resins are preferred, with three-dimensionally cross-linked acrylic resins being even more preferred.
  • the use of such resins tends to further improve the polishing rate.
  • the resins that make up the polishing portion may be used alone or in combination of two or more types.
  • the composite particles contain diamond abrasive grains as abrasive particles, which are components that contribute to polishing.
  • the composite particles may be those described in the first embodiment.
  • the composite microparticles contain diamond abrasive grains and matrix particles. This increases the polishing efficiency because new abrasive microparticles are exposed from the inside as the matrix particles wear down.
  • 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 greater tends to prevent the abrasive microparticles from easily detaching from the composite microparticles, thereby preventing a decrease in the polishing rate. It also tends to prevent scratches on the workpiece caused by the rolling of detached diamond abrasive grains.
  • a crushing strength of 300.0 MPa or less tends to 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, thereby preventing a deterioration in surface roughness.
  • the standard deviation (SD) of the crushing strength of the composite microparticles 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. Having a standard deviation within the above range results in a certain degree of variation in the crushing strength of the composite microparticles. In other words, the presence of both composite microparticles that are easy to abrade and composite microparticles that are difficult to abrade tends to result in excellent self-dressing properties for the polishing pad and an improved polishing rate.
  • crushing strength refers to the average value of the crushing strengths of five composite microparticles measured using the crushing strength measurement method described below. Furthermore, 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.
  • 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 preferably 15.0 to 70.0%, more preferably 25.0 to 68.0%, and even more preferably 30.0 to 65.0%.
  • SD/Cs standard deviation
  • the average particle diameter (Da) of the composite microparticles is preferably 10 to 100 ⁇ m, more preferably 25 to 95 ⁇ m, and even more preferably 35 to 90 ⁇ m. By having an average particle diameter within this range, the composite microparticles are less likely to detach from the polishing pad, maintaining a more stable polishing rate, while also tending to reduce the surface roughness of the resulting polished object.
  • the content of the composite microparticles is preferably 1.5 to 40.0 mass% relative to the total amount of the polishing portion, more preferably 2.5 to 35.0 mass%, and even more preferably 3.5 to 10.0 mass%.
  • the polishing rate tends to be further improved.
  • the content of the composite microparticles is 40.0 mass% or less, the grinding force tends to be further improved.
  • the components constituting the abrasive microparticles 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 component with the highest grinding ability.
  • diamond abrasive grains for example, those described in the first embodiment can be mentioned. Among them, diamond abrasive grains have the best grinding ability.
  • These abrasive microparticles can be used alone or in combination of two or more types.
  • the average particle diameter (Dd) of the abrasive microparticles varies depending on the workpiece and process, but is preferably 1.0 to 20.0 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10.0 ⁇ m. Having an average particle diameter within the above range tends to prevent the abrasive microparticles from causing deep scratches on the workpiece.
  • the ratio (Dd/Da) of the average particle size (Dd) of the abrasive microparticles to the average particle size (Da) of the composite microparticles is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20.
  • the content of abrasive microparticles is preferably 1.0 to 30.0 mass% of the total amount of composite microparticles, more preferably 3.0 to 20.0 mass%, and even more preferably 5.0 to 15.0 mass%.
  • Matrix Particles The components constituting the matrix particles are not particularly limited, but include, for example, those described in the first embodiment. Among these, silicon dioxide, boron oxide, and zinc oxide are preferred. It is more preferable to use glass frit, which is a powder made by melting and molding a glass material primarily composed of silicon dioxide, boron oxide, and zinc oxide. The use of such matrix particles results in composite particles strong enough to hold the abrasive particles without causing crushing of the composite particles due to grinding of the matrix particles during conditioning. This tends to maintain more stable polishing while further reducing the surface roughness of the resulting polished object. These matrix particles may be used alone or in combination of two or more types.
  • the average particle size of the powdered matrix particles may be within the range described in the first embodiment. It is preferably 1.0 to 20 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10 ⁇ m. If the average particle size is about the same as the abrasive particles, it is more likely to be distributed uniformly within the composite particles, which is preferable as it reduces variation in grinding ability between composite particles.
  • the ratio of the average particle size of the matrix particles to the average particle size of the composite microparticles may be within the range described in the first embodiment. It is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20.
  • the average particle size ratio within the above range, when the composite particles are formed, the fixing force of the abrasive microparticles is excellent, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the matrix particle content is preferably 10 to 98% by mass, more preferably 25 to 95% by mass, and even more preferably 50 to 90% by mass, relative to the total amount of composite microparticles.
  • the matrix particle content is within the above range, the spacing between the abrasive microparticles increases, there is less contact between the abrasive microparticles and the workpiece during polishing, the load per abrasive microparticle increases, and the grinding force increases, tending to improve the polishing rate.
  • auxiliary particles are not particularly limited, but examples include the auxiliary particles having an average particle size of 0.5 to 4.5 ⁇ m described in the first embodiment. By using such auxiliary particles, blocking between composite fine particles is suppressed, and the polishing rate tends to improve.
  • the auxiliary particles may be located on the surface of the composite fine particle. Furthermore, the components constituting the auxiliary particles may be those described in the first embodiment. The average particle size of the auxiliary particles may be within the range described in the first embodiment.
  • the average particle size of the auxiliary particles may be within the range described in the first embodiment. It is preferably 0.5 to 4.5 ⁇ m, more preferably 0.7 to 4.0 ⁇ m, and even more preferably 0.9 to 3.5 ⁇ m. By having the average particle size within the above range, blocking of the composite microparticles can be effectively suppressed, the polishing rate can be improved, and the surface roughness of the resulting polished object can be further reduced.
  • the content of auxiliary particles is preferably 1.0 to 60.0 mass% of the total amount of composite microparticles, more preferably 10.0 to 55.0 mass%, and even more preferably 30.0 to 50.0 mass%.
  • the content of auxiliary particles is preferably 1.0 to 10 mass% of the total amount of the polishing portion, more preferably 1.5 to 7.5 mass%, and even more preferably 1.5 to 5.0 mass%.
  • Spacer Particles examples include those described in the first embodiment. Among them, wollastonite is preferred from the viewpoint of the fixing power of the composite fine particles and self-dressing properties.
  • the average particle size of the spacer particles may be within the range described in the first embodiment, 5.0 to 20 ⁇ m, preferably 7.5 to 17.5 ⁇ m, and more preferably 10 to 15 ⁇ m.
  • the particle size is low and the fluidity is high, resulting in excellent moldability. This also improves the disintegration of the polishing area, better maintains the polishing rate, and tends to further suppress scratches.
  • the ratio of the average particle size of the composite microparticles to the average particle size of the spacer particles may be within the range described in the first embodiment, and is preferably 1.5 to 10, more preferably 2.5 to 9.0, and even more preferably 3.5 to 8.0. If the ratio is 1.5 or higher, the spacer particles can be densely packed around the composite abrasive grains, making it easier to fix the composite microparticles. If the ratio is 10 or lower, 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 workpiece can be more stably maintained.
  • the aspect ratio (average major axis diameter/average minor axis diameter) of the spacer particles may be within the range described in the first embodiment, and is 2.0 to 12, preferably 2.5 to 10, and more preferably 3.0 to 7.0. Having an aspect ratio (average major axis diameter/average minor axis diameter) within the above range provides appropriate self-dressing properties, allows the polishing rate to be maintained more stably, and reduces the surface roughness of the resulting polished object. There are no particular restrictions on the method for measuring the aspect ratio of the spacer particles, but it can be calculated from photographs taken with an electron microscope.
  • the content of spacer particles is preferably 40 to 70 mass% of the total amount of the polishing portion, more preferably 45 to 65 mass%, and even more preferably 50 to 60 mass%. By keeping the content of spacer particles within this range, the self-dressing properties of the spacer particles allow new composite microparticles to continue to appear, making the polishing rate more stable and tending to further reduce the surface roughness of the polished object.
  • the ratio of the spacer particle content to the composite microparticle content is preferably 1.5 to 22.5, more preferably 2.5 to 17.5, and even more preferably 5.0 to 12.5.
  • the ratio of the spacer particle content to the composite microparticle content is within the above range, the spacing between the composite microparticles becomes appropriate, the load on the composite microparticles is more evenly distributed, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the polishing pad of the second 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.
  • the adhesive layer may be made of, for example, the materials described in the first embodiment.
  • the adhesive layer may also be, for example, double-sided tape.
  • the method for manufacturing a polishing pad of the second 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, wherein the crushing strength of the composite microparticles is 100 to 300 MPa.
  • the firing step may be the firing step described in the first embodiment.
  • the firing temperature in the firing step may be within the temperature range described in the first embodiment, and is preferably equal to or higher than the yield point of the matrix particles. If the firing temperature is equal to or higher than the yield 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 will not bond together, making it difficult to produce composite microparticles.
  • the firing temperature is preferably the yield point of the matrix particles + 150°C or less, more preferably the yield point of the matrix particles + 120°C or less, even more preferably the yield point of the matrix particles + 100°C or less, and even more preferably the yield point of the matrix particles + 80°C or less.
  • the lower limit of the firing temperature is preferably equal to or higher than the yield point of the matrix particles. If the firing temperature is equal to or lower than the yield point of the matrix particles + 150°C, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention force of the composite particles can be kept within a suitable range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other and will need to be crushed after firing, which may result in distorted shapes of the composite particles and impair the abrasive grain retention force of the composite particles.
  • the firing temperature depends on the yield point of the 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 to 630°C. If the firing temperature is within the above range, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention power of the composite particles can be kept within an appropriate range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other, requiring them to be crushed after firing, which can result in distorted shapes of the composite particles and may impair the composite particles' ability to retain the abrasive grains.
  • the firing time in the firing step is, for example, 0.5 to 30 hours. This may be adjusted as appropriate to obtain the desired composite microparticles.
  • the atmosphere used in the firing process is not particularly limited, but is preferably an air atmosphere.
  • the matrix particles tend to fuse together and bond appropriately, which tends to stabilize variations in the crushing strength of the composite microparticles.
  • the atmosphere used in the firing process is not particularly limited, but an open system is preferable.
  • 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 device may be either a static firing furnace or a fluidized bed firing furnace.
  • a static firing furnace When a static firing furnace is used, the material to be fired is fired in a container such as a sheath. In this case, a temperature difference occurs between the area where the composite particles contact the sheath and the center of the composite particles, or between the composite particles that are in contact with the firing atmosphere and the composite particles that are not in contact with the firing atmosphere, making it easy for differences in thermal history to occur.
  • the crushing strength of the composite particles can be within a suitable range.
  • the variation in the crushing strength of the composite particles can be within a suitable range.
  • both easily abradable and resistant 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.
  • the composite particle precursor preparation process may be a process of mixing diamond abrasive grains, matrix particles, binder resin, dispersant, and solvent to prepare a composite particle precursor composition, and then granulating the composite particle precursor.
  • the binder resin, dispersant, and solvent may be those described in the first embodiment.
  • additives may be blended into the composite microparticle precursor composition.
  • examples of other additives include deflocculants (dispersants) and surfactants. These additives may be used alone or in combination of two or more.
  • the method for granulating the composite microparticle precursor composition is not particularly limited, but examples include a method using a spray dryer or other spray dryer. In this method, the precursor composition is sprayed into heated air and the solvent (dispersion liquid) is evaporated to obtain precursor particles.
  • the granulation conditions are not particularly limited and can be set appropriately 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; for example, if water is used as the solvent, it may be 150 to 250°C.
  • the curing step is a step of obtaining a polishing part by curing a curable composition containing a resin and composite fine particles.
  • the curable composition is not particularly limited as long as it contains a resin and composite particles, but examples 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; and a curable composition containing a two-component mixed curable resin. Furthermore, the curable composition may contain a crosslinking agent having two or more polymerizable functional groups, as necessary.
  • the photopolymerization initiator, polymerization initiator, thermosetting resin, and UV-curable resin described in the first embodiment can be used.
  • the curable composition may contain components other than the resin, composite microparticles, and polymerization initiator.
  • Such components include, for example, the fillers and auxiliary particles described above.
  • the curing method of 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.
  • 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.
  • the polishing part and the substrate may be bonded by applying the curable composition to the substrate and curing the curable composition.
  • the surface of the polishing part opposite the polishing surface, which has been cured in advance may be bonded to the substrate via an adhesive.
  • the method for applying the curable composition to the substrate is not particularly limited, but examples include the methods described in the first embodiment. Among these, screen printing or transfer printing is preferred from the standpoint of ease of forming complex concave-convex patterns and productivity.
  • the method may further include a step of bonding the substrate on which the abrasive portion is disposed to another substrate.
  • the surface of the substrate opposite the surface on which the abrasive portion is disposed is bonded to the other substrate via an adhesive.
  • the type of adhesive used is not particularly limited, and may be liquid, double-sided tape, or adhesive tape made from an adhesive processed into a tape-like material. Examples of liquid adhesives include curing adhesives such as photocurable resins, thermosetting resins, and moisture-curable resins, solvent-volatile adhesives, and hot-melt adhesives.
  • the adhesive can be applied using any conventional method known in the art. Examples include printing, such as screen printing, spray application, and application with a roller or brush.
  • the method for producing a polishing pad of the second embodiment may include other steps, if necessary. For example, it may include a step of volatilizing and removing at least a portion of the volatile components in the curable composition before the curing step. Furthermore, it may include a step of removing a portion of the curable composition or the polishing portion before and/or after the curing step to form a desired uneven pattern. Examples of the removal method include cutting.
  • the manufacturing method of the polished product of the second 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.
  • a coolant may also be used in the polishing.
  • the object to be polished is not particularly limited, but examples include those described in the first embodiment.
  • the method for manufacturing a polished product of the second embodiment is particularly suitable for use as a method for manufacturing magnetic disks such as hard disk drives, glass substrates used as the base material for reflective masks used in lithography using EUV light, glass used as a material for LCD substrates and cover glass for mobile devices 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.
  • 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 a conventionally known method and is not particularly limited.
  • a polishing pad is attached to a predetermined position on the polishing device. During this attachment, the polishing pad is attached so that it is fixed to the polishing device via the adhesive layer described above. Then, the workpiece to be polished is held on a holding platen positioned opposite the polishing pad, which serves as a polishing platen, and pressed against the polishing surface. Coolant is supplied from outside while the polishing pad and/or holding platen are rotated. This allows the coolant supplied between the polishing pad and the workpiece to act to reduce polishing resistance and remove polishing debris, while polishing the workpiece surface (surface to be polished).
  • polishing Pad A polishing pad according to a third embodiment includes a substrate and a polishing portion disposed on the substrate, the polishing portion including a resin and composite fine particles, the composite fine particles including diamond abrasive grains, and the composite fine particles including hollow composite fine particles, and the content of the hollow composite fine particles is 5 to 40 mass % relative to the total amount of the composite fine particles.
  • FIG. 1 shows a schematic perspective view of a polishing pad according to a third embodiment.
  • this polishing pad 10 comprises a substrate 11 and a polishing portion 12 disposed on the substrate 11.
  • multiple convex portions formed by the polishing portion 12 are arranged on the surface of the substrate 11, forming an uneven pattern.
  • the polishing portion 12 may form a concave-convex pattern together with the substrate 11 as shown in Figure 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 12 formed by punching out dots from a uniform layer, or any other pattern.
  • Figure 2 shows a schematic cross-sectional view of a polishing pad according to a third embodiment.
  • the polishing portion 12 of the polishing pad 10 according to the third embodiment contains composite particles 14 and resin 15.
  • the polishing surface of the polishing portion 12 is gradually worn away, and the composite particles 14 embedded in the polishing portion 12 are exposed, forming a new polishing surface, which tends to maintain the polishing rate.
  • the contact area between the polishing surface of the polishing pad and the workpiece is reduced, effectively applying a load to the workpiece, which tends to improve polishing performance.
  • hollow composite particles improves self-dressing properties, making them less susceptible to glazing, and preventing a decrease in the polishing rate even during long-term polishing. Furthermore, when a processing fluid is used, the processing fluid can be retained in the open hollow portion, improving polishing efficiency.
  • Substrate is a member on which the polishing section 12 is formed, and may be attached to the polishing device via an adhesive layer, which will be described later.
  • the substrate is not particularly limited, but examples include those described in the first embodiment. Among these, polyester sheets are preferred from the standpoints of chemical resistance, heat resistance, and economy, while acrylic sheets are preferred from the standpoints of rigidity and adhesiveness.
  • the abrasive section contains a resin and composite particles, and may contain other spacer particles as needed.
  • the abrasive section 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).
  • the abrasive section 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.
  • the polishing section to have an uneven pattern, and more preferably to have a regular uneven pattern. Having a regular pattern makes uniform polishing possible, and polishing with excellent surface quality can be achieved.
  • a regular pattern refers to a pattern obtained by arranging multiple small unit patterns. The surface of the polishing section opposite the substrate serves as the polishing surface for polishing the workpiece.
  • the uneven pattern is not particularly limited as long as it has portions that come into contact with the workpiece (convex portions) and portions that do not come into contact with the workpiece (concave portions).
  • Examples include a positive pattern (a pattern with dot-shaped convex portions) in which the polishing portions 12 are independently formed on the substrate 11 as shown in Figure 1, as well as the uneven pattern described in the first embodiment. Of these, a pattern with dot-shaped convex portions is preferred. Having such an uneven pattern tends to further improve the ability to remove polishing debris.
  • the three-dimensional shape of the dots is not particularly limited, and examples include the shapes described in the first embodiment.
  • the frustum shape may be a frustum shape that widens from the substrate side toward the polishing surface side, or a frustum shape that widens from the polishing surface side toward the substrate side.
  • the three-dimensional shape of the space in the recesses can be exemplified as being similar to the three-dimensional shape in the case of a pattern having dot-shaped protrusions.
  • the resin is not particularly limited, but is preferably a thermosetting resin or a photocurable resin, such as those described in the first embodiment.
  • acrylic resins polyurethane resins, unsaturated polyester resins, and phenol-modified alkyd resins are preferred, with three-dimensionally cross-linked acrylic resins being more preferred. Using such resins tends to prevent excessive wear of the polishing pad, allowing it to be used for a long period of time.
  • the resins that make up the polishing portion may be used alone or in combination of two or more types.
  • the composite particles contain diamond abrasive grains as abrasive particles, which are components that contribute to polishing.
  • the composite particles may be those described in the first embodiment.
  • the composite microparticles contain diamond abrasive grains, which are abrasive microparticles, and matrix particles. This increases the polishing efficiency because new abrasive microparticles are exposed from the inside as the matrix particles wear down.
  • the composite microparticles of the third embodiment include hollow composite microparticles, which are hollow composite microparticles having an outer shell (shell portion) and a hollow structure with a hollow interior (see Figure 3).
  • the composite microparticles may also include other composite microparticles, for example, solid composite microparticles that are not hollow inside.
  • the crushing strength (Cs) of the composite microparticles is preferably 50.0 to 300.0 MPa, more preferably 60.0 to 200.0 MPa, and even more preferably 70.0 to 160.0 MPa. Having a crushing strength within the above range tends to prevent the abrasive microparticles from easily detaching from the composite microparticles, thereby preventing a decrease in the polishing rate. It also tends to prevent scratches on the workpiece caused by the rolling of detached diamond abrasive grains. Furthermore, after the dressing process, scratches on the workpiece caused by the diamond abrasive grains being fixed in a protruding state on the polishing surface can be prevented, and a deterioration in surface roughness tends to be prevented.
  • crushing strength refers to the average value of the crushing strengths of five composite microparticles measured using the crushing strength measurement method described below. Furthermore, 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.
  • the average particle diameter (Da) of the composite microparticles is preferably 20 to 100 ⁇ m, more preferably 25 to 90 ⁇ m, and even more preferably 30 to 80 ⁇ m. By having an average particle diameter within this range, the composite microparticles are less likely to detach from the polishing pad, maintaining a more stable polishing rate, while also tending to reduce the surface roughness of the resulting polished object.
  • the content of the composite microparticles is preferably 1.5 to 25.0 mass% relative to the total amount of the polishing portion, more preferably 2.5 to 22.0 mass%, and even more preferably 3.5 to 20.0 mass%.
  • the polishing rate tends to be further improved.
  • the content of the composite microparticles is 25.0 mass% or less, the grinding force tends to be further improved.
  • Hollow Composite Microparticles include hollow composite microparticles.
  • Hollow composite microparticles are hollow bodies with an outer shell (shell portion) and a hollow structure with a hollow cavity inside. Hollow composite microparticles can be confirmed as hollow bodies by observing the cross section of the polishing portion or the cross section of the composite microparticle using a scanning electron microscope (SEM) or the like.
  • the shell portion of the hollow composite microparticles contains diamond abrasive grains, preferably diamond abrasive grains and matrix grains. The diamond abrasive grains may be dispersed within the matrix grains.
  • the shape of the hollow composite microparticles is not particularly limited, but examples include spherical, elliptical, and shapes similar to these.
  • the average particle size of the hollow composite microparticles is preferably 20 to 100 ⁇ m, more preferably 25 to 90 ⁇ m, and even more preferably 30 to 80 ⁇ m. By keeping the average particle size within this range, the abrasive microparticles can be encapsulated in the shell portion, which tends to improve polishing performance.
  • the average particle size can also be adjusted appropriately by adjusting the concentration of the hollow composite microparticle precursor composition slurry, the spray dryer granulation conditions (spray amount, spray pressure, nozzle diameter, hot air temperature), etc.
  • the shell thickness of the hollow composite microparticles is preferably 5 to 35 ⁇ m, more preferably 6 to 30 ⁇ m, and even more preferably 7 to 25 ⁇ m. Having a shell thickness within this range allows the abrasive microparticles to be enclosed within the shell, which tends to improve polishing performance.
  • the shell thickness can be measured using microscopic photographs of the cross section of the abrasive portion or the cross section of the hollow composite microparticles.
  • the shell thickness can also be adjusted appropriately by adjusting the firing temperature, firing time, and firing atmosphere, such as the amount of oxygen, when preparing the hollow composite microparticles, as well as the solids concentration and drying speed when preparing the hollow composite microparticle precursor.
  • the crushing strength ( Cs1 ) of the hollow composite particles is preferably 15.0 to 130.0 MPa, more preferably 20.0 to 120.0 MPa, and even more preferably 30.0 to 110.0 MPa.
  • the crushing strength is within the above range, the hollow composite particles tend to disintegrate appropriately easily, and self-dressing ability tends to be improved. As a result, they are less likely to be crushed, and even during long-term polishing, a decrease in the polishing rate can be suppressed, and a stable polishing rate tends to be obtained.
  • the content of hollow composite microparticles is 5 to 40% by mass, preferably 7 to 38% by mass, and more preferably 9 to 36% by mass, of the total amount of composite microparticles. Having a content of hollow composite microparticles within this range reduces the contact area between the polishing surface of the polishing pad and the workpiece, effectively applying a load to the workpiece and tending to improve polishing performance. Furthermore, the inclusion of hollow composite microparticles tends to improve self-dressing properties, making them less susceptible to glazing, and inhibiting a decrease in polishing rate even during long-term polishing. Furthermore, when using a processing fluid, the open hollow portion can retain the processing fluid, tending to improve polishing efficiency.
  • the composite particles may include solid composite particles in addition to hollow composite particles.
  • Solid composite particles are composite particles having a solid structure. The solid structure of the solid composite particles can be confirmed by observing the cross section of the polished portion or the cross section of the composite particles using a scanning electron microscope (SEM) or the like.
  • the average particle size of the solid composite microparticles is preferably 20 to 100 ⁇ m, more preferably 25 to 90 ⁇ m, and even more preferably 30 to 80 ⁇ m. By having an average particle size within this range, the composite microparticles are less likely to detach from the polishing pad, maintaining a more stable polishing rate, while also tending to reduce the surface roughness of the resulting polished object.
  • the crushing strength ( Cs2 ) of the solid composite microparticles is preferably 100.0 to 300.0 MPa, more preferably 100.0 to 200.0 MPa, and even more preferably 120.0 to 160.0 MPa.
  • a crushing strength of 100.0 MPa or more tends to prevent the abrasive microparticles from easily detaching from the composite microparticles, and tends to prevent a decrease in the polishing rate. It also tends to prevent scratches on the polished object caused by the rolling of the detached diamond abrasive grains.
  • a crushing strength of 300.0 MPa or less tends to prevent the diamond abrasive grains from being fixed in a protruding state on the polishing surface after the dressing step, and to prevent a deterioration in the surface roughness of the polished object.
  • the content of solid composite microparticles is 60 to 95 mass% of the total amount of composite microparticles, preferably 62 to 93 mass%, and more preferably 64 to 91 mass%.
  • the difference between the crushing strength ( Cs1 ) of the hollow composite microparticles and the crushing strength ( Cs2 ) of the solid composite microparticles is preferably 40.0 to 100.0 MPa, more preferably 45.0 to 85.0 MPa, and even more preferably 50.0 to 70.0 MPa.
  • the difference between the crushing strength ( Cs1 ) of the hollow composite microparticles and the crushing strength ( Cs2 ) of the solid composite microparticles is within the above range, appropriate self-dressing properties are obtained, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the components constituting the abrasive microparticles 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 component with the highest grinding ability.
  • diamond abrasive grains for example, those described in the first embodiment can be mentioned. Among them, diamond abrasive grains have the best grinding ability.
  • These abrasive microparticles can be used alone or in combination of two or more types.
  • the average particle diameter (Dd) of the abrasive microparticles varies depending on the workpiece and process, but is preferably 1.0 to 20.0 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10.0 ⁇ m. By keeping the average particle diameter within this range, it is possible to prevent the abrasive microparticles from causing deep scratches on the workpiece.
  • the ratio (Dd/Da) of the average particle size (Dd) of the abrasive microparticles to the average particle size (Da) of the composite microparticles is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20.
  • the average particle size of the diamond abrasive grains varies depending on the workpiece and process, but is preferably 1.0 to 20.0 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10.0 ⁇ m. By keeping the average particle size within this range, it is possible to prevent the abrasive particles from causing deep scratches in the workpiece. In addition, the abrasive particles can be encapsulated in the shell portion, which tends to improve polishing performance.
  • the content of abrasive microparticles is preferably 1.0 to 30.0 mass% of the total amount of composite microparticles, more preferably 3.0 to 20.0 mass%, and even more preferably 5.0 to 15.0 mass%.
  • Matrix Particles The components constituting the matrix particles are not particularly limited, but include, for example, those described in the first embodiment. Among these, silicon dioxide, boron oxide, and zinc oxide are preferred. It is more preferable to use glass frit, which is a powder made by melting and molding a glass material primarily composed of silicon dioxide, boron oxide, and zinc oxide. The use of such matrix particles results in composite particles strong enough to hold the abrasive particles without causing crushing of the composite particles due to grinding of the matrix particles during conditioning, allowing for 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 of two or more types.
  • the average particle size of the powdered matrix particles may be within the range described in the first embodiment. It is preferably 1.0 to 20 ⁇ m, more preferably 2.0 to 12.5 ⁇ m, and even more preferably 3.0 to 10 ⁇ m. If the average particle size is about the same as the abrasive particles, it is more likely to be distributed uniformly within the composite particles, which is preferable as it reduces variation in grinding ability between composite particles.
  • the ratio of the average particle size of the matrix particles to the average particle size of the composite microparticles may be within the range described in the first embodiment. It is preferably 0.01 to 0.40, more preferably 0.03 to 0.30, and even more preferably 0.05 to 0.20.
  • the average particle size ratio within the above range, when the composite particles are formed, the fixing force of the abrasive microparticles is excellent, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the matrix particle content is preferably 10 to 98% by mass, more preferably 25 to 95% by mass, and even more preferably 50 to 90% by mass, relative to the total amount of composite microparticles.
  • the matrix particle content is within the above range, the spacing between the abrasive microparticles increases, there is less contact between the abrasive microparticles and the workpiece during polishing, the load per abrasive microparticle increases, and the grinding force increases, tending to improve the polishing rate.
  • auxiliary particles are not particularly limited, but examples thereof include auxiliary particles having an average particle diameter (Db) of 0.5 to 4.5 ⁇ m. By using such auxiliary particles, blocking of the composite fine particles is suppressed, and the polishing rate tends to improve.
  • the auxiliary particles may be located on the surface of the composite fine particles.
  • auxiliary particles are not particularly limited, but examples include those described in the first embodiment.
  • auxiliary particles containing such components blocking of the composite microparticles tends to be suppressed, and the polishing rate tends to improve.
  • These auxiliary particles may be used alone, or two or more types may be used in combination.
  • the average particle size of the auxiliary particles may be within the range described in the first embodiment. It is preferably 0.5 to 4.5 ⁇ m, more preferably 0.7 to 4.0 ⁇ m, and even more preferably 0.9 to 3.5 ⁇ m. By having the average particle size within the above range, blocking of the composite microparticles can be effectively suppressed, the polishing rate can be improved, and the surface roughness of the resulting polished object can be further reduced.
  • the content of auxiliary particles is preferably 1.0 to 60.0 mass% of the total amount of composite microparticles, more preferably 10.0 to 55.0 mass%, and even more preferably 20 to 50.0 mass%.
  • the content of auxiliary particles is preferably 1.0 to 25.0 mass% relative to the total amount of the polishing portion, more preferably 2.0 to 22.0 mass%, and even more preferably 3.0 to 20.0 mass%.
  • Spacer Particles examples include those described in the first embodiment. Among them, wollastonite is preferred from the viewpoint of the fixing power of the composite fine particles and self-dressing properties.
  • the average particle size of the spacer particles may be within the range described in the first embodiment, 5.0 to 20 ⁇ m, preferably 7.5 to 17.5 ⁇ m, and more preferably 10 to 15 ⁇ m.
  • the particle size is low and the fluidity is high, resulting in excellent moldability. This also improves the disintegration of the polishing area, better maintains the polishing rate, and tends to further suppress scratches.
  • the ratio of the average particle size of the composite microparticles to the average particle size of the spacer particles may be within the range described in the first embodiment, and is preferably 1.5 to 10, more preferably 2.5 to 9.0, and even more preferably 3.5 to 8.0. If the ratio is 1.5 or higher, the spacer particles can be densely packed around the composite abrasive grains, making it easier to fix the composite microparticles. If the ratio is 10 or lower, 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 workpiece can be more stably maintained.
  • the aspect ratio (average major axis diameter/average minor axis diameter) of the spacer particles may be within the range described in the first embodiment, and is 2.0 to 12, preferably 2.5 to 10, and more preferably 3.0 to 7.0. Having an aspect ratio (average major axis diameter/average minor axis diameter) within the above range provides appropriate self-dressing properties, allows the polishing rate to be maintained more stably, and reduces the surface roughness of the resulting polished object. There are no particular restrictions on the method for measuring the aspect ratio of the spacer particles, but it can be calculated from photographs taken with an electron microscope.
  • the content of spacer particles is preferably 20 to 70 mass% of the total amount of the polishing portion, more preferably 23 to 65 mass%, and even more preferably 25 to 60 mass%.
  • the ratio of the spacer particle content to the composite microparticle content is preferably 1.0 to 22.5, more preferably 1.1 to 17.5, and even more preferably 1.2 to 12.5.
  • the spacing between the composite microparticles becomes appropriate, the load on the composite microparticles is more easily equalized, the polishing rate can be maintained more stably, and the surface roughness of the resulting polished object tends to be reduced.
  • the polishing pad of the third 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.
  • the adhesive layer may be made of, for example, the materials described in the first embodiment.
  • the adhesive layer may also be, for example, double-sided tape.
  • a manufacturing method of a polishing pad according to a third embodiment includes a firing step of firing a composite particle precursor containing diamond abrasive grains and matrix particles to obtain composite particles, a curing step of curing a curable composition containing a resin and the composite particles to obtain a polishing part, and a bonding step of bonding a surface of the polishing part opposite to the polishing surface to a substrate, wherein the composite particles include hollow composite particles, and the content of the hollow composite particles is 5 to 40 mass % relative to the total amount of the composite particles.
  • the firing process is a process of firing a composite microparticle precursor containing diamond abrasive grains and matrix particles to obtain composite microparticles.
  • the firing process may include a composite microparticle precursor preparation process containing diamond abrasive grains and matrix particles.
  • the composite microparticle precursor preparation process may include a hollow composite microparticle precursor preparation process and a solid composite microparticle precursor preparation process.
  • the composite microparticle precursor obtained by the composite microparticle precursor preparation process described below is fired to thermally decompose the binder resin in the composite microparticle precursor, and fuse and appropriately bond the matrix particles together.
  • the aforementioned auxiliary particles may also be included and fired.
  • the auxiliary particles blocking between the composite microparticle precursors can be suppressed.
  • the firing temperature in the firing step may be within the temperature range described in the first embodiment, and is preferably equal to or higher than the yield point of the matrix particles. If the firing temperature is equal to or higher than the yield point of the matrix particles, the matrix particles tend to fuse together and bond appropriately, further improving the stability of the composite microparticles. If the firing temperature is too low, the matrix particles will not bond together, reducing the strength of the composite microparticles and resulting in inferior polishing performance when used in a polishing pad.
  • the firing temperature is preferably the yield point of the matrix particles + 150°C or less, more preferably the yield point of the matrix particles + 120°C or less, even more preferably the yield point of the matrix particles + 100°C or less, and even more preferably the yield point of the matrix particles + 80°C or less.
  • the lower limit of the firing temperature is preferably equal to or higher than the yield point of the matrix particles. If the firing temperature is equal to or lower than the yield point of the matrix particles + 150°C, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention force of the composite particles can be kept within a suitable range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other and will need to be crushed after firing, which may result in distorted shapes of the composite particles and impair the abrasive grain retention force of the composite particles.
  • the firing temperature depends on the yield point of the 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 560 to 630°C. If the firing temperature is within the above range, bonding of the composite particles to each other tends to be suppressed, while the diamond abrasive grain retention power of the composite particles can be kept within an appropriate range. Furthermore, if the firing temperature is too high, the composite particles will bond to each other, requiring them to be crushed after firing, which can result in distorted shapes of the composite particles and may impair the composite particles' ability to retain the abrasive grains.
  • the atmosphere used in the firing process is not particularly limited, but is preferably an air atmosphere.
  • the matrix particles tend to fuse together and bond appropriately, which tends to stabilize variations in the crushing strength of the composite microparticles.
  • the atmosphere used in the firing process is not particularly limited, but is preferably an open system.
  • 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 device may be either a static firing furnace or a fluidized firing furnace.
  • a static firing furnace When a static firing furnace is used, the material to be fired is fired in a container such as a sheath.
  • a temperature difference occurs between the area where the composite microparticles contact the sheath and the center of the composite microparticles, or between the composite microparticles in contact with the firing atmosphere and the composite microparticles not in contact with the firing atmosphere, making it easy for differences in thermal history to occur.
  • This creates an appropriate variation in the thermal history of the composite microparticles allowing the crushing strength of the composite microparticles to be within a suitable range.
  • the crushing strength can be adjusted to a suitable range by adjusting the firing time.
  • the composite microparticle precursor preparation process may be a process of mixing diamond abrasive grains, matrix particles, binder resin, dispersant, and solvent to prepare a composite microparticle precursor composition, and then granulating the composite microparticle precursor.
  • the composite microparticle precursor preparation process may include a hollow composite microparticle precursor preparation process and a solid composite microparticle precursor preparation process.
  • the binder resin, dispersant, and solvent can be those described in the first embodiment.
  • additives may be blended into the composite microparticle precursor composition.
  • examples of other additives include deflocculants (dispersants) and surfactants. These additives may be used alone or in combination of two or more.
  • the method for granulating the composite microparticle precursor composition is not particularly limited, but examples include a method using a spray dryer or other spray dryer. In this method, the precursor composition is sprayed into heated air and the solvent (dispersion liquid) is evaporated to obtain precursor particles.
  • the granulation conditions are not particularly limited and can be set appropriately depending on the desired composite microparticles.
  • the hollow composite particle precursor preparation process may be a process of mixing diamond abrasive grains, matrix particles, a binder resin, a dispersant, and a solvent to prepare a hollow composite particle precursor composition, and then granulating the hollow composite particle precursor.
  • the solids concentration of the hollow composite microparticle precursor composition is not particularly limited, but is preferably 5 to 40%, more preferably 10 to 35%, even more preferably 15 to 30%, and especially preferably 15 to 25%. Having a solids concentration within the above range tends to make it possible to produce hollow composite microparticles.
  • the method for granulating the hollow composite microparticle precursor composition is not particularly limited, but examples include methods using a spray dryer or other spray dryer, with granulation using a spray dryer being preferred.
  • the inlet temperature of the spray dryer can be set appropriately depending on the solids concentration of the hollow composite particle precursor composition, and is not particularly limited, but is preferably 130 to 310°C, more preferably 140 to 300°C, and even more preferably 150 to 290°C. By setting the inlet temperature higher within the above range, liquid components such as water tend to evaporate rapidly, forming hollow structures inside and enabling more efficient granulation of the hollow composite particle precursor.
  • the outlet temperature of the spray dryer can be set appropriately depending on the solids concentration of the hollow composite particle precursor composition, and is not particularly limited, but is preferably 80 to 160°C, more preferably 85 to 155°C, and even more preferably 90 to 150°C. By keeping the outlet temperature within the above range, the hollow composite particle precursor tends to be granulated more efficiently.
  • the solid composite particle precursor preparation process may be a process of mixing diamond abrasive grains, matrix particles, a binder resin, a dispersant, and a solvent to prepare a solid composite particle precursor composition, and then granulating the solid composite particle precursor.
  • the solids concentration of the solid composite microparticle precursor composition is not particularly limited, but is preferably 40-80%, more preferably 45-75%, even more preferably 50-70%, and especially preferably 55-65%. Having a solids concentration within the above range tends to make it possible to produce solid composite microparticles.
  • the method for granulating the solid composite microparticle precursor composition is not particularly limited, but examples include methods using a spray dryer, and granulation using a spray dryer is preferred.
  • the inlet temperature of the spray dryer can be set appropriately depending on the solids concentration of the solid composite particle precursor composition, and is not particularly limited, but is preferably 100 to 270°C, more preferably 110 to 260°C, and even more preferably 120 to 250°C. By keeping the inlet temperature within the above range, liquid components such as water tend to gradually volatilize, making it possible to more efficiently granulate the solid composite particle precursor.
  • the outlet temperature of the spray dryer can be set appropriately depending on the solids concentration of the solid composite particle precursor composition, and is not particularly limited, but is preferably 70 to 150°C, more preferably 75 to 135°C, and even more preferably 80 to 120°C. By keeping the outlet temperature within the above range, the solid composite particle precursor tends to be granulated more efficiently.
  • the curing step is a step of obtaining a polishing part by curing a curable composition containing a resin and composite fine particles.
  • the curable composition is not particularly limited as long as it contains a resin and composite particles, but examples 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; and a curable composition containing a two-component mixed curable resin. Furthermore, the curable composition may contain a crosslinking agent having two or more polymerizable functional groups, as necessary.
  • the photopolymerization initiator, polymerization initiator, thermosetting resin, and UV-curable resin described in the first embodiment can be used.
  • the curable composition may contain components other than the resin, composite microparticles, and polymerization initiator.
  • Such components include, for example, the fillers and auxiliary particles described above.
  • the curing method of 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.
  • 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.
  • the polishing part and the substrate may be bonded by applying the curable composition to the substrate and curing the curable composition.
  • the surface of the polishing part opposite the polishing surface, which has been cured in advance may be bonded to the substrate via an adhesive.
  • the method for applying the curable composition to the substrate is not particularly limited, but examples include the methods described in the first embodiment. Among these, screen printing or transfer printing is preferred from the standpoint of ease of forming complex concave-convex patterns and productivity.
  • the method may further include a step of bonding the substrate on which the abrasive portion is disposed to another substrate.
  • the surface of the substrate opposite the surface on which the abrasive portion is disposed is bonded to the other substrate via an adhesive.
  • the type of adhesive used is not particularly limited, and may be liquid, double-sided tape, or adhesive tape made from an adhesive processed into a tape-like material. Examples of liquid adhesives include curing adhesives such as photocuring resins, thermosetting resins, and moisture-curing resins, solvent-volatile adhesives, and hot-melt adhesives.
  • the adhesive can be applied using any conventional method known in the art. Examples include printing, such as screen printing, spray application, and application with a roller or brush.
  • the type of adhesive used to bond the surface opposite the abrasive surface of the pre-cured abrasive portion to the substrate is not particularly limited, and any of the adhesives listed above may be used as appropriate.
  • the method for manufacturing a polishing pad of the third embodiment may include other steps, etc., as necessary. For example, it may include a step of volatilizing and removing at least a portion of the volatile components in the curable composition before the curing step. Furthermore, it may include a step of removing a portion of the curable composition or the polishing portion before and/or after the curing step to form a desired uneven pattern. Examples of the removal method include cutting.
  • the manufacturing method of the polished product of the third 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.
  • a coolant may also be used in the polishing.
  • the object to be polished is not particularly limited, but examples include those described in the first embodiment.
  • the method for manufacturing a polished product of the third embodiment is particularly suitable for use as a method for manufacturing magnetic disks such as hard disk drives, glass substrates used as the base material for reflective masks used in lithography using EUV light, glass used as a material for LCD substrates and cover glass for mobile devices 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.
  • 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 a conventionally known method and is not particularly limited.
  • a polishing pad is attached to a predetermined position on the polishing device. During this attachment, the polishing pad is attached so that it is fixed to the polishing device via the adhesive layer described above. Then, the workpiece to be polished is held on a holding platen positioned opposite the polishing pad, which serves as a polishing platen, and pressed against the polishing surface. Coolant is supplied from outside while the polishing pad and/or holding platen are rotated. This allows the coolant supplied between the polishing pad and the workpiece to act to reduce polishing resistance and remove polishing debris, while polishing the workpiece surface (surface to be polished).
  • Example Group 1 Preparation Example 1-1 (Preparation of Composite Fine Particles) 12 parts by mass of dextrin (manufactured by Tokai Dextrin), 40 parts by mass of purified water, 1 part by mass of additive Cerna D-735 (manufactured by Chukyo Yushi), 42.3 parts by mass of glass frit, and 4.7 parts by mass of diamond powder with an average particle size of 4 ⁇ m were mixed to prepare a slurry. Then, the mixture was spray-dried using a spray dryer at an atomizer rotation speed of 10,000 rpm to form a composite particle precursor.
  • the composite particle precursor and white alumina (manufactured by Fujimi Co., Ltd., average particle size 3 ⁇ m) were mixed in a ratio of 5:5 (mass ratio), placed in an open-top container, and calcined at 600 ° C. for 4 hours to obtain composite particles A with an average particle size of 61.7 ⁇ m.
  • Preparation Example 1-2 Composite particles B having an average particle size of 61.7 ⁇ m were obtained in the same manner as in Preparation Example 1-1, except that the blending amount of glass frit was changed to 33 parts by mass and the blending amount of diamond powder was changed to 14 parts by mass.
  • Preparation Example 1-3 Composite fine particles D having an average particle size of 35.6 ⁇ m were obtained in the same manner as in Preparation Example 1-1, except that the atomizer rotation speed of the spray dryer was changed to 20,000 rpm.
  • SR368D manufactured by Sartomer Corporation
  • a dispersant Solsperse 32000 manufactured by Lubrizol Japan Co., Ltd.
  • a photopolymerization initiator Irgacure 819 manufactured by BASF Japan Ltd.
  • the obtained curable composition was poured into a molding silicone intaglio plate consisting of a square truncated pyramidal recess with a depth of 1 mm, a cavity opening dimension of 3.0 mm x 3.0 mm, a recess bottom dimension of 2.4 mm x 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 irradiated with ultraviolet light from above using an ultraviolet irradiator to cure the curable composition.
  • the obtained cured product (polishing part) was removed from the molding die, and a 1 mm thick acrylic substrate was bonded to the surface irradiated with ultraviolet light 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, heated at 90 degrees in a dryer for 12 hours, and processed into a donut-shaped shape with an outer diameter of 910 mm and an inner diameter of 370 mm, thereby obtaining a polishing pad having a convex portion on the polishing part of Example 1-1.
  • Examples 1-2, 1-4 and 1-5, Comparative Examples 1-1 and 1-2 A polishing pad was obtained in the same manner as in Example 1-1, except that the type and blending amount of the composite fine particles and the blending amounts of the resin and filler were changed as shown in Table 1.
  • Examples 1-3 A polishing pad was obtained in the same manner as in Example 1-1, except that the type and amount of composite microparticles, and the amount of resin and filler were changed as shown in Table 1, and the molding silicone intaglio was changed to a molding silicone intaglio consisting of a square pyramidal truncated recess with a depth of 1 mm, dimensions of the cavity opening of 5.0 mm x 5.0 mm, dimensions of the bottom of the recess of 4.0 mm x 4.0 mm, and a spacing between adjacent openings of 2 mm.
  • the surface of a 370 mm diameter polishing pad obtained during the manufacturing process was ground 150 ⁇ m from the surface using a diamond dresser, and the polished surface of the convex portions was then baked at 400°C for 3 hours.
  • An elemental mapping analysis of the polished surface was then performed using a scanning transmission electron microscope (STEM) equipped with an energy dispersive X-ray analyzer (EDS). From the resulting mapping image, the number of composite microparticles was counted using the image processing software ImageJ, and the proportion of composite microparticles contained relative to the area of the polished surface of the convex portions was calculated. The results are shown in Table 1.
  • 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 a measurement time of 10 seconds using a laser diffraction particle size distribution analyzer "Microtrac MT3300EXII" manufactured by Microtrac Bell Co., Ltd.
  • the refractive index during measurement was 1.61, and the refractive index of the medium (deionized water) was 1.333.
  • the arithmetic mean height Sa of polished object, maximum height roughness Sz The arithmetic mean height Sa and maximum height roughness Sz of the surface of the workpiece after grinding were measured using a non-contact white light interferometer (manufactured by Zygo, product name "NewView 5022").
  • evaluation criteria (Arithmetic mean height Sa of the workpiece) ⁇ : The arithmetic mean height Sa of the glass is less than 50 nm. ⁇ : The arithmetic mean height Sa of the glass is 50 nm or more (maximum height roughness Sz of the polished object). ⁇ : The maximum height roughness of the glass is less than 2000 nm. ⁇ : The maximum height roughness of the glass is 2000 nm or more.
  • the polishing rate represents the amount of glass polished per minute, and was calculated from the mass loss of the glass before and after polishing the seventh batch. (Polishing rate evaluation criteria) ⁇ : 20 mg/min or more ⁇ : Less than 20 mg/min
  • the polishing pad of the first embodiment has a polishing portion with convex portions, the polishing portion containing resin and composite microparticles, the composite microparticles containing diamond abrasive grains, the ratio (Da/Dd) of the average particle diameter (Da) of the composite microparticles to the average particle diameter (Dd) of the diamond abrasive grains being 8.0 to 20.0, and the diamond abrasive grain content being 0.50 to 2.00 mass% relative to the total amount of the convex portions, which has been shown to exhibit a stable polishing rate, good surface roughness of the workpiece, and high planarization precision.
  • Example Group 2 Preparation Example 2-1 (Preparation of Composite Fine 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), 42 parts by weight of glass frit, and 5 parts by weight of diamond powder with an average particle size of 3 ⁇ m were mixed to prepare a slurry. Then, a composite particle precursor was formed by spray drying using a spray dryer.
  • Preparation Example 2-2 Composite fine particles B having an average particle size of 40 ⁇ m were obtained in the same manner as in Preparation Example 2-1, except that the calcination was carried out at 580° C.
  • Preparation Example 2-3 Composite fine particles C having an average particle size of 40 ⁇ m were obtained in the same manner as in Preparation Example 2-1, except that the calcination was carried out at 610° C.
  • Preparation Example 2-4 Composite particles D having an average particle size of 40 ⁇ m were obtained in the same manner as in Preparation Example 2-1, except that diamond powder having an average particle size of 9 ⁇ m was used.
  • Preparation Example 2-5 Composite fine particles E having an average particle size of 40 ⁇ m were obtained in the same manner as in Preparation Example 2-1, except that the mixture was placed in a container sealed with a lid and baked at 580° C. for 2 hours.
  • Preparation Example 2-6 Composite particles F having an average particle size of 40 ⁇ m were obtained in the same manner as in Preparation Example 2-1, 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.
  • SR368D manufactured by Sartomer Corporation
  • a dispersant Solsperse 32000 manufactured by Lubrizol Japan Co., Ltd.
  • a photopolymerization initiator Irgacure 819 manufactured by BASF Japan Ltd.
  • 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 irradiated with ultraviolet light from above using an ultraviolet irradiator to cure the curable composition.
  • the obtained cured product (abrasive part) was removed from the mold, and a 1 mm thick acrylic substrate was bonded to the surface irradiated with ultraviolet light 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, to obtain a polishing pad of Example 2-1 with a diameter of 300 mm.
  • Example 2-2 to 2-4 Polishing pads were obtained in the same manner as in Example 2-1, except that composite particles B, C, D, E and F were used instead of composite particles A.
  • 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 a measurement time of 10 seconds using a laser diffraction particle size distribution analyzer "Microtrac MT3300EXII" manufactured by Microtrac Bell Co., Ltd.
  • the refractive index during measurement was 1.61, and the refractive index of the medium (deionized water) was 1.333.
  • the crushing strength (Cs) can be 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 (in the formula, ⁇ is the ratio of the circumference of a circle to its diameter). The average value of the crushing strength for the five particles is shown in Table 2.
  • Crushing strength (Cs) 2.48 ⁇ P/ ⁇ d 2
  • 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 variation, and the standard deviation of the composite microparticles was divided by the average value of the crushing strength to determine the degree of variation (%) of the composite microparticle strength.
  • the surface roughness Ra of the workpiece was measured using an optical interferometer (manufactured by Canon, trade name "Zygo NewView 5010"). (Evaluation criteria) ⁇ : The surface roughness Sa of the glass is less than 40 nm. ⁇ : The surface roughness Sa of the glass is 40 nm or more.
  • polishing rate stability was also evaluated based on the following criteria. (Polishing rate evaluation criteria) ⁇ : 20 mg/min or more ⁇ : less than 20 mg/min (Polishing rate stability evaluation criteria) ⁇ : Less than 10% ⁇ : 10% or more
  • the polishing pad of the second embodiment has an abrasive portion that contains resin and composite microparticles, and the composite microparticles contain diamond abrasive grains.
  • the crushing strength of the composite microparticles is 100 to 300 MPa, which demonstrates a stable polishing rate, good surface roughness of the workpiece, and high flattening precision.
  • Comparative Example 2-1 on the other hand, the crushing strength of the composite microparticles was extremely low, so diamond abrasive grains easily detached from the composite microparticles, reducing the polishing rate. Furthermore, the large variation in crushing strength resulted in a lack of polishing rate stability, and the detached diamond abrasive grains also worsened the surface roughness. In Comparative Example 2-2, the crushing strength of the composite microparticles was low, so diamond abrasive grains detached from the composite microparticle shells, reducing the polishing rate, and the detached diamond abrasive grains also worsened the surface roughness.
  • Example Group 3 Preparation of hollow composite particles 4 parts by weight of dextrin (manufactured by Tokai Dextrin), 80 parts by weight of purified water, 11.2 parts by weight of glass frit, and 4.8 parts by weight of diamond powder with an average particle diameter of 4 ⁇ m were mixed to prepare a composite particle precursor composition with a solids concentration of 20%. Then, using a spray dryer, the mixture was spray-dried under conditions of a discharge flow rate of 1.5 L/min, an inlet temperature of 280 ° C, an outlet temperature of 140 ° C, and a spindle rotation speed of 10,000 rpm to form a composite particle precursor.
  • the composite particle precursor and white alumina (manufactured by Fujimi Co., Ltd., average particle diameter 3 ⁇ m) were mixed in a ratio of 6:4, placed in an open-top container, and calcined at 590 ° C for 2 hours to obtain composite microparticles with an average particle diameter of 40 ⁇ m.
  • SEM scanning electron microscope
  • Preparation Example 3-2 (Preparation of solid 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), 42 parts by weight of glass frit, and 5 parts by weight of diamond powder with an average particle size of 4 ⁇ m were mixed to prepare a composite particle precursor composition with a solid content of 60%. Thereafter, using a spray dryer, the mixture was spray-dried under the conditions of a discharge flow rate of 1.5 L / min, an inlet temperature of 220 ° C, an outlet temperature of 90 ° C, and a spindle rotation speed of 10,000 rpm to form a composite particle precursor.
  • the composite particle precursor and white alumina (manufactured by Fujimi Co., Ltd., average particle size 3 ⁇ m) were mixed in a ratio of 6:4, placed in an open-top container, and fired at 590 ° C for 2 hours to obtain composite particles with an average particle size of 40 ⁇ m.
  • SEM scanning electron microscope
  • SR368D manufactured by Sartomer Corporation
  • a dispersant Solsperse 32000 manufactured by Lubrizol Japan Co., Ltd.
  • a photopolymerization initiator Irgacure 819 manufactured by BASF Japan Ltd.
  • the obtained curable composition was poured into a molding silicone intaglio plate having a rectangular prism-shaped recess with a depth of 1 mm, a cavity opening dimension of 3.0 mm x 3.0 mm, a recess bottom dimension of 2.4 mm x 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, to obtain a polishing pad of Example 3-1 having a diameter of 300 mm.
  • Example 3-2 Comparative Examples 3-1 and 3-2
  • a polishing pad was obtained in the same manner as in Example 3-1, except that the blending ratio of the hollow composite fine particles to the solid composite fine particles was changed to the blending ratio shown in Table 3.
  • 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 a measurement time of 10 seconds using a laser diffraction particle size distribution analyzer "Microtrac MT3300EXII" manufactured by Microtrac Bell Co., Ltd.
  • the refractive index during measurement was 1.61, and the refractive index of the medium (deionized water) was 1.333.
  • the crushing strength (Cs) can be 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 microparticles using the following formula (in the formula, ⁇ is the ratio of the circumference of a circle to its diameter). The average value of the crushing strength for the five particles is shown in Table 3.
  • Crushing strength (Cs) 2.48 ⁇ P/ ⁇ d 2
  • the surface roughness Sa of the workpiece was measured using an optical interferometer (manufactured by Canon, trade name "Zygo NewView 5010"). (Evaluation criteria) ⁇ : The surface roughness Sa of the glass is less than 50 nm. ⁇ : The surface roughness Sa of the glass is 50 nm or more.
  • polishing rate stability was also evaluated based on the following criteria. (Polishing rate evaluation criteria) ⁇ : 20 mg/min or more ⁇ : less than 20 mg/min (Polishing rate stability evaluation criteria) ⁇ : Less than 10% ⁇ : 10% or more
  • the polishing pad of the third embodiment contains hollow composite microparticles in the polishing portion, and the content of these hollow composite microparticles is 5 to 40 mass% of the total amount of composite microparticles, which shows a stable polishing rate, good surface roughness of the polished object, and high planarization precision.
  • Comparative Example 3-1 where the hollow composite microparticle content was 40% by mass or more relative to the total amount of composite microparticles, the polishing rate decreased and the polishing rate lacked stability, possibly due to the hollow composite microparticles falling off the polishing pad during the dressing process. Furthermore, in Comparative Example 3-2, where the hollow composite microparticles were 5% by mass or less, the surface roughness of the polished object deteriorated, possibly due to poor self-dressing properties.
  • the polishing pads of the first, second, and third embodiments have industrial applicability as polishing pads 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.
  • polishing pad 11... Substrate, 12... Polishing portion, 13... Convex portion, 14... Composite fine particles, 15... Resin, 17... Polishing surface.

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Abstract

Le but de la présente invention est de fournir un tampon de polissage avec lequel il est possible d'obtenir un objet poli ayant une faible rugosité de surface tout en maintenant un taux de polissage stable, et de fournir un procédé de fabrication du tampon de polissage. En particulier, il est proposé un tampon de polissage ou similaire comprenant un matériau de base et une partie de polissage disposée sur le matériau de base, la partie de polissage ayant des parties saillantes, la partie de polissage comprenant une résine et des particules fines composites, les particules fines composites comprenant des grains abrasifs de diamant, le rapport (Da/Dd) du diamètre de particule moyen (Da) des particules fines composites au diamètre de particule moyen (Dd) des grains abrasifs de diamant étant de 8,0 à 20,0, et le rapport de teneur des grains abrasifs de diamant étant de 0,50 à 2,00 % en masse par rapport à la quantité totale des parties saillantes.
PCT/JP2025/006216 2024-03-22 2025-02-25 Tampon de polissage et son procédé de fabrication Pending WO2025197434A1 (fr)

Applications Claiming Priority (6)

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JP2024047182A JP2025146423A (ja) 2024-03-22 2024-03-22 研磨パッド及びその製造方法
JP2024-047196 2024-03-22
JP2024-047174 2024-03-22
JP2024-047182 2024-03-22
JP2024047196A JP2025146434A (ja) 2024-03-22 2024-03-22 研磨パッド及びその製造方法
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2023068452A (ja) * 2021-11-02 2023-05-17 バンドー化学株式会社 研磨パッド
JP2023124056A (ja) * 2022-02-25 2023-09-06 富士紡ホールディングス株式会社 研磨パッド及びその製造方法
JP2023148907A (ja) * 2022-03-30 2023-10-13 富士紡ホールディングス株式会社 研磨パッドの製造方法及び研磨パッド

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2023068452A (ja) * 2021-11-02 2023-05-17 バンドー化学株式会社 研磨パッド
JP2023124056A (ja) * 2022-02-25 2023-09-06 富士紡ホールディングス株式会社 研磨パッド及びその製造方法
JP2023148907A (ja) * 2022-03-30 2023-10-13 富士紡ホールディングス株式会社 研磨パッドの製造方法及び研磨パッド

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