Polishing composition and polishing method using the same

Abstract

The present invention provides a means for decreasing a surface roughness (Ra) while keeping a high polishing speed in the polishing of an object comprising a resin and a filler. A polishing composition according to the present invention is intended to be used for the polishing of an object comprising a resin and a filler, the polishing composition comprising alumina particles, colloidal silica particles and a dispersion medium, in which the average particle diameter of the alumina particles is smaller than 2.8 μm and the average particle diameter of the colloidal silica particles is smaller than the average particle diameter of the alumina particles.

Description

[Technical Field]

[0001] The present invention relates to a polishing composition and a polishing method using the same. [Background technology]

[0002] In recent years, new microfabrication technologies have been developed in response to the increasing integration and performance of LSIs. Chemical mechanical polishing (hereinafter abbreviated as "CMP") is one such technology, and it is frequently used in LSI manufacturing processes, especially in the process of forming multilayer wiring.

[0003] The CMP method is also used to polish the surface of resins, and by applying the CMP method, resin products with fewer surface defects can be obtained. For this reason, various studies have been conducted on polishing compositions for polishing various materials, including resins.

[0004] JP 2016-183212 A discloses a polishing composition for polishing a polishing object, which contains a resin having high rigidity and high strength. More specifically, JP 2016-183212 A discloses that a polishing composition containing abrasive grains having a Mohs hardness and surface acidity of a predetermined value or more and a dispersion medium can polish even a resin having high rigidity and high strength at a high polishing rate. JP 2016-183212 A also discloses that, from the viewpoint of polishing rate, abrasive grains mainly composed of α-alumina are preferred.

[0005] Japanese Patent Laid-Open No. 2007-063442 discloses a polishing composition for polishing synthetic resin objects.More specifically, Japanese Patent Laid-Open No. 2007-063442 discloses that by using a polishing composition that contains a polyurethane polymer surfactant with a specific structure and has a predetermined viscosity range, it is possible to prevent the reduction of the polishing composition and the deterioration of polishing ability when polishing synthetic resins.In addition, Japanese Patent Laid-Open No. 2007-063442 also discloses that, from the viewpoint of polishing speed, it is preferable that the polishing composition further contains α-alumina as abrasive grains. Summary of the Invention

[0006] However, while the techniques described in JP 2016-183212 A and JP 2007-063442 A can achieve high polishing rates, there is a trade-off problem in that the surface roughness (Ra) of the resin increases.

[0007] Therefore, an object of the present invention is to provide a means for reducing the surface roughness (Ra) while maintaining a high polishing rate when polishing a resin-containing object to be polished.

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by using a combination of alumina particles having a specific particle size and colloidal silica particles smaller than the alumina particles as abrasive grains, thereby completing the present invention.

[0009] That is, the above-mentioned problems of the present invention can be solved by the following means.

[0010] A polishing composition used for polishing an object to be polished that contains a resin and a filler, the polishing composition comprising alumina particles, colloidal silica particles, and a dispersion medium, wherein the alumina particles have an average particle diameter of less than 2.8 μm, and the colloidal silica particles have an average particle diameter smaller than that of the alumina particles. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the claims. Throughout this specification, singular expressions should be understood to include the plural concept unless otherwise specified. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept unless otherwise specified. Furthermore, terms used in this specification should be understood to have the meaning commonly used in the relevant field unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the case of conflict, the present specification (including definitions) will prevail.

[0012] In this specification, the range "X to Y" includes X and Y and means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20°C or more and 25°C or less) and at a relative humidity of 40% RH or more and 50% RH or less.

[0013] <Polishing composition> One aspect of the present invention relates to a polishing composition used for polishing a polishing target containing a resin and a filler, the polishing composition comprising alumina particles, colloidal silica particles, and a dispersion medium, wherein the alumina particles have an average particle size of less than 2.8 μm, and the colloidal silica particles have an average particle size smaller than that of the alumina particles. By using the above-described specific alumina particles and colloidal silica particles in combination as abrasives, it is possible to reduce the surface roughness (Ra) while maintaining a high polishing rate when polishing a polishing target containing a resin and a filler. Below, each component contained in the polishing composition according to the present invention is described in detail. Hereinafter, the alumina particles will also be referred to as the "first abrasive grains," and the colloidal silica particles will also be referred to as the "second abrasive grains."

[0014] [Abrasive grain] <Alumina particles (primary abrasive grains)> The polishing composition of the present invention contains alumina particles having an average particle size of less than 2.8 μm as abrasive grains (first abrasive grains). The abrasive grains mechanically polish the object to be polished, thereby improving the polishing rate. The alumina particles have sufficient hardness, and are therefore highly effective in improving the polishing rate, particularly for various materials including resins.

[0015] The average particle size (average secondary particle size) of the alumina particles is less than 2.8 μm. If the average particle size of the alumina particles is 2.8 μm or more, the surface of the object to be polished after polishing will be excessively rough (Comparative Examples 9 and 10 below). The average particle size of the alumina particles is preferably 2.0 μm or less, more preferably less than 1.5 μm, even more preferably less than 1.2 μm, and particularly preferably less than 0.8 μm. The average particle size of the alumina particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably more than 0.2 μm, and particularly preferably 0.3 μm or more. Within the above range, an improvement in the polishing rate and a reduction in surface roughness can be achieved in a better balance. A preferred example of the average particle diameter of the alumina particles is 0.1 μm or more and 2.0 μm or less, more preferably 0.2 μm or more and less than 1.5 μm, even more preferably more than 0.2 μm and less than 1.2 μm, and particularly preferably 0.3 μm or more and less than 0.8 μm. The average particle diameter (average secondary particle diameter) of the alumina particles is the particle diameter (D 50 ) where D of the alumina particles 50 is determined by dynamic light scattering, laser diffraction, laser scattering, or pore electrical resistance, etc. Specifically, the value determined by the measurement method described in the Examples below is used.

[0016] The alumina particles are not particularly limited, and examples thereof include alumina particles containing at least one selected from α-alumina, γ-alumina, δ-alumina, θ-alumina, η-alumina, and κ-alumina.

[0017] The concentration (content) of the alumina particles is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, and particularly preferably 1.5% by mass or more, relative to the total mass of the polishing composition. As the concentration of the alumina particles increases, the polishing rate improves. Furthermore, the concentration (content) of the alumina particles is preferably 25% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably less than 9% by mass, and particularly preferably 8% by mass or less, relative to the total mass of the polishing composition. Within the above range, the surface roughness is reduced, and the occurrence of defects such as scratches is further reduced. A preferred example of the concentration (content) of alumina particles is 0.01% by mass or more and 25% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, even more preferably 0.5% by mass or more and 10% by mass or less, particularly preferably 1% by mass or more and less than 9% by mass, and most preferably 1.5% by mass or more and 8% by mass or less, based on the total mass of the polishing composition.Within the above range, improvement of the polishing rate and reduction of the surface roughness can be achieved in a well-balanced manner.

[0018] The alumina particles can be easily produced by appropriately referring to known production methods (for example, JP 2017-190267 A), and commercially available alumina particles may also be used.

[0019] The alumina particles may be used alone or in combination of two or more kinds.

[0020] <Colloidal silica particles (secondary abrasive grains)> The polishing composition of the present invention contains, as abrasive grains (second abrasive grains), colloidal silica particles having an average particle size smaller than that of alumina particles. Colloidal silica particles have a lower hardness than alumina particles, and therefore reduce surface roughness. By combining alumina particles that improve the polishing rate with colloidal silica particles that reduce surface roughness, it is possible to achieve a good balance between the trade-off between improving the polishing rate and reducing the surface roughness.

[0021] The average particle size (average secondary particle size) of the colloidal silica particles is smaller than the average particle size (average secondary particle size) of the alumina particles. If the average particle size of the colloidal silica particles is larger than the average particle size of the alumina particles, it becomes difficult to obtain the effect of reducing surface roughness. The average particle size of the colloidal silica particles is preferably 0.20 μm or less, more preferably less than 0.20 μm, even more preferably 0.15 μm or less, and particularly preferably less than 0.10 μm. The average particle size of the colloidal silica particles is preferably 0.005 μm or more, more preferably 0.02 μm or more, even more preferably 0.06 μm or more, and particularly preferably 0.07 μm or more. Within the above range, an improvement in the polishing rate and a reduction in surface roughness can be achieved in a better balance. A preferred example of the average particle size of the colloidal silica particles is 0.005 μm or more and 0.20 μm or less, more preferably 0.02 μm or more and less than 0.20 μm, even more preferably 0.06 μm or more and 0.15 μm or less, and particularly preferably 0.07 μm or more and less than 0.10 μm. The average particle size (average secondary particle size) of the colloidal silica particles is the particle size (D 50 ) where the average particle diameter of the colloidal silica particles (D 50 ) can be determined by dynamic light scattering, laser diffraction, laser scattering, or pore electrical resistance, etc. Specifically, the value determined by the measurement method described in the Examples below is used.

[0022] Colloidal silica particles have a span value [(D 90 -D10 ) / D 50 ], and a span value [(D 90 -D 10 ) / D 50 ], and more preferably has a span value [(D 90 -D 10 ) / D 50 ], and more preferably has a span value [(D 90 -D 10 ) / D 50 ], where the span value [(D 90 -D 10 ) / D 50 ] is an index showing the uniformity of particle size distribution, and is the particle size (D 90 ) to the particle diameter (D 10 ) minus the value (D 90 -D 10 ) is the particle size at which the cumulative frequency from the small particle size side in the volume-based particle size distribution is 50% (D 50 ) to three decimal places and round off to the nearest [(D 90 -D 10 ) / (D 50 The volume-based particle size distribution is determined by the measurement method described in the Examples below. 90 -D 10 ) / D 50 The smaller the value, the sharper the particle size distribution, and the larger the value, the broader the particle size distribution.

[0023] Furthermore, the ratio of the average particle size (average secondary particle size) of alumina particles to the average particle size (average secondary particle size) of colloidal silica particles (average particle size of alumina particles / average particle size of colloidal silica particles) exceeds 1. The ratio of the average particle size (average secondary particle size) of alumina particles to the average particle size (average secondary particle size) of colloidal silica particles (average particle size of alumina particles / average particle size of colloidal silica particles) is preferably 1.1 or more, more preferably greater than 1.5, even more preferably 2.0 or more, and particularly preferably greater than 3.0. The ratio of the average particle size (average secondary particle size) of alumina particles to the average particle size (average secondary particle size) of colloidal silica particles (average particle size of alumina particles / average particle size of colloidal silica particles) is preferably 25.0 or less, more preferably less than 20.0, even more preferably less than 15.0, and particularly preferably less than 5.0. Within the above ranges, an improvement in the polishing rate and a reduction in surface roughness can be achieved in a well-balanced manner. A preferred example of the ratio of the average particle size (average secondary particle size) of alumina particles to the average particle size (average secondary particle size) of colloidal silica particles (average particle size of alumina particles / average particle size of colloidal silica particles) is 1.1 or more and 25.0 or less, more preferably more than 1.5 and less than 20.0, even more preferably 2.0 or more and less than 15.0, and particularly preferably more than 3.0 and less than 5.0.

[0024] The concentration (content) of the colloidal silica particles is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably more than 1% by mass, particularly preferably 2% by mass or more, and particularly preferably 2.5% by mass or more, relative to the total mass of the polishing composition. The higher the concentration of the colloidal silica particles, the more improved the polishing rate. Furthermore, the concentration (content) of the colloidal silica particles is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably less than 10% by mass, and particularly preferably 8% by mass or less, relative to the total mass of the polishing composition. Within the above range, the surface roughness is reduced, and the occurrence of defects such as scratches is further reduced. A preferred example of the concentration (content) of colloidal silica particles is, relative to the total mass of the polishing composition, preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, even more preferably more than 1% by mass or more and 10% by mass or less, particularly preferably 2% by mass or more and 10% by mass or less, and particularly preferably 2.5% by mass or more and 8% by mass or less. Within the above range, an improvement in the polishing rate and a reduction in surface roughness can be achieved in a well-balanced manner.

[0025] The mixing mass ratio of alumina particles to colloidal silica particles (alumina particle concentration (content) / colloidal silica particle concentration (content)) is not particularly limited, but is preferably 0.1 or more, more preferably 0.2 or more, even more preferably greater than 0.2, and particularly preferably 0.3 or more. The mixing mass ratio of alumina particles to colloidal silica particles (alumina particle concentration (content) / colloidal silica particle concentration (content)) is preferably 10.0 or less, more preferably less than 8.0, even more preferably 5.0 or less, and particularly preferably less than 5.0. Within the above ranges, an improved polishing rate and reduced surface roughness can be achieved in a better balance. A preferred example of the mixing mass ratio of alumina particles to colloidal silica particles (alumina particle concentration (content) / colloidal silica particle concentration (content)) is 0.1 or more and 10.0 or less, more preferably 0.2 or more and less than 8.0, even more preferably greater than 0.2 and less than 5.0, and particularly preferably 0.3 or more and less than 5.0.

[0026] Colloidal silica particles can be easily produced by appropriately referring to known production methods. Commercially available colloidal silica particles may also be used. Methods for producing colloidal silica include the sodium silicate method, the alkoxide method, and the sol-gel method. Colloidal silica produced by any of these methods can be suitably used as the colloidal silica of the present invention.

[0027] In one embodiment, the raw colloidal silica is colloidal silica obtained by a sodium silicate method, which typically uses activated silicic acid obtained by ion-exchanging an aqueous solution of an alkali silicate such as water glass as a raw material and grows the particles of the activated silicic acid.

[0028] In one embodiment, the raw colloidal silica is colloidal silica obtained by the alkoxide method, which typically uses an alkoxysilane as a raw material and subjects it to a hydrolysis and condensation reaction.

[0029] The type of colloidal silica particles used is not particularly limited, but for example, surface-modified colloidal silica can be used. For example, the colloidal silica particles may have a cationic group. A preferred example of colloidal silica having a cationic group is colloidal silica with an amino group fixed to the surface. As a method for producing such colloidal silica with a cationic group, there is a method described in JP 2005-162533 A, in which a silane coupling agent having an amino group, such as aminoethyltrimethoxysilane, aminopropyltrimethoxysilane, aminoethyltriethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, or aminobutyltriethoxysilane, is fixed to the surface of the abrasive grain. This allows for the production of colloidal silica with an amino group fixed to the surface (amino group-modified colloidal silica).

[0030] The colloidal silica particles may have anionic groups. Preferred examples of colloidal silica having anionic groups include colloidal silica having anionic groups such as carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and aluminic acid groups fixed to the surface. The method for producing such colloidal silica having anionic groups is not particularly limited, and examples thereof include a method of reacting colloidal silica with a silane coupling agent having an anionic group at its terminal.

[0031] As a specific example, sulfonic acid groups can be immobilized on colloidal silica by the method described in "Sulfonic acid-functionalized silica through thiol groups," Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, is coupled to colloidal silica, and then the thiol group is oxidized with hydrogen peroxide to obtain colloidal silica having sulfonic acid groups immobilized on the surface.

[0032] Alternatively, if carboxylic acid groups are to be immobilized on colloidal silica, this can be achieved by, for example, the method described in "Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel," Chemistry Letters, 3, 228-229 (2000). Specifically, colloidal silica having carboxylic acid groups immobilized on its surface can be obtained by coupling a silane coupling agent containing a photolabile 2-nitrobenzyl ester to colloidal silica and then irradiating the resulting mixture with light.

[0033] The colloidal silica particles may be used alone or in combination of two or more kinds.

[0034] [Dispersion medium] The polishing composition of the present invention contains a dispersion medium that disperses or dissolves each component.

[0035] The dispersion medium preferably contains water.Furthermore, from the viewpoint of preventing the influence of impurities on other components of the polishing composition, it is preferable to use water with as high purity as possible.Specifically, it is preferable to use pure water or ultrapure water, which has been removed impurity ions by ion exchange resin and then filtered to remove foreign matter, or distilled water.Furthermore, the dispersion medium may further contain an organic solvent or the like for the purpose of controlling the dispersibility of other components of the polishing composition.

[0036] [pH adjuster] The polishing composition according to one embodiment of the present invention preferably further contains a pH adjuster, which can contribute to adjusting the pH of the polishing composition by selecting the type and amount of the pH adjuster.

[0037] The pH adjuster is not particularly limited as long as it is a compound having a pH adjusting function, and known compounds can be used. The pH adjuster is not particularly limited as long as it is a compound having a pH adjusting function, and examples thereof include acids and alkalis.

[0038] The acid may be either an inorganic acid or an organic acid. Inorganic acids include, but are not limited to, sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid. Organic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, and lactic acid, as well as methanesulfonic acid, ethanesulfonic acid, and isethionic acid. Among these, organic acids are preferred, with malic acid, citric acid, and maleic acid being more preferred. When an inorganic acid is used, nitric acid, sulfuric acid, or phosphoric acid is preferred.

[0039] The alkali is not particularly limited, but examples thereof include alkali metal hydroxides such as potassium hydroxide, ammonia, quaternary ammonium salts such as tetramethylammonium and tetraethylammonium, amines such as ethylenediamine and piperazine, etc. Among these, potassium hydroxide and ammonia are preferred.

[0040] The pH adjusters may be used alone or in combination of two or more.

[0041] The content of the pH adjuster is not particularly limited, and is preferably an amount that allows the pH value to be adjusted to a value within the preferred range described below.

[0042] [Other ingredients] The polishing composition of the present invention may further contain known components such as abrasive grains, chelating agents, thickeners, oxidizers, dispersants, surface protective agents, wetting agents, surfactants, anticorrosives (rust inhibitors), preservatives, and antifungal agents, as well as dispersion stabilizers described below, provided that the effects of the present invention are not impaired. The content of these other components may be appropriately determined depending on the purpose of their addition. The dispersion stabilizer includes at least one phosphorus-containing acid selected from the group consisting of phosphoric acid and its condensates, organic phosphoric acid, phosphonic acid, and organic phosphonic acid. In this specification, "organic phosphoric acid" refers to an organic compound having at least one phosphoric acid group (-OP(=O)(OH)2), and "organic phosphonic acid" refers to an organic compound having at least one phosphonic acid group (-P(=O)(OH)2). In this specification, "phosphoric acid and its condensates and organic phosphoric acid" are also referred to simply as "phosphoric acid-based acids," and "phosphonic acid and organic phosphonic acid" are also referred to simply as "phosphonic acid-based acids." These phosphorus-containing acids have the function of modifying (inverting) the zeta potential of alumina particles to negative (-). The alumina particles with negative (-) zeta potential then electrostatically repel each other, suppressing aggregation and improving the redispersibility of the concentrate.

[0043] Specific examples of phosphorus-containing acids include phosphoric acid (orthophosphoric acid), pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, hexametaphosphoric acid, methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid (myo-inositol-1,2,3,4,5,6-hexaphosphate), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), nitrilotris ( Examples of suitable phosphonic acids include 1-hydroxyethylidene-1,1-diphosphonic acid (NTMP), ethylenediaminetetra(methylenephosphonic acid) (EDTMP), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethanehydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, and methanehydroxyphosphonic acid. Among these, from the viewpoint of achieving a good balance between redispersibility, polishing rate, and etching rate, phosphonic acids are preferred, organic phosphonic acids are more preferred, and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP), and ethylenediaminetetra(methylenephosphonic acid) (EDTMP) are even more preferred. The phosphorus-containing acids may be used singly or in combination of two or more.

[0044] [pH] The pH of the polishing composition according to this embodiment is preferably 1 or more and 6 or less, or 8 or more and 12 or less, more preferably more than 1 and less than 5, or more than 8 and less than 11, and particularly preferably 1.5 or more and less than 4. Within the above ranges, an improvement in the polishing rate and a reduction in surface roughness can be achieved in a better balance. In particular, when the polishing composition is acidic, the polishing rate can be further improved. The pH of the polishing composition can be determined by the measurement method described in the Examples below.

[0045] [Method for producing polishing composition] The manufacturing method (preparation method) of the polishing composition is not particularly limited, and for example, a manufacturing method including stirring and mixing alumina particles, colloidal silica particles, a dispersion medium (preferably water), and other components as necessary can be appropriately adopted. Note that the alumina particles, colloidal silica particles, dispersion medium, and other components are the same as those described in the above section on <Polishing composition>, so their description will be omitted here.

[0046] The temperature at which the components are mixed is not particularly limited, but is preferably 10 to 40° C. Heating may be performed to increase the dissolution rate. The mixing time is also not particularly limited.

[0047] [Polished object] The object to be polished with the polishing composition of the present invention contains a resin and a filler.

[0048] Here, the resin is not particularly limited, but examples thereof include acrylic resins such as polymethyl(meth)acrylate, methyl methacrylate-methyl acrylate copolymer, and urethane(meth)acrylate resin; epoxy resin; olefin resin such as ultra-high molecular weight polyethylene (UHPE); phenolic resin; polyamide resin (PA); polyimide resin (PI); polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and unsaturated polyester resin; polycarbonate resin (PC); polyphenylene sulfide resin; polystyrene resin such as syndiotactic polystyrene (SPS); polynorbornene resin; polybenzoxazole (PBO); polyacetal (POM); modified polyphenylene ether (m-PPE); amorphous polyarylate (PAR); polysulfone (PSF); polyethersulfone (PES); polyphenylene sulfide (PPS); polyetheretherketone (PEEK); polyetherimide (PEI); fluororesin; and liquid crystal polymer (LCP). In this specification, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid, as well as both acrylic acid and methacrylic acid. Similarly, in this specification, "(meth)acrylate" refers to acrylate or methacrylate, as well as both acrylate and methacrylate. Of these, from the viewpoint of processability, it is preferable that the resin has a cyclic molecular structure. That is, in a preferred embodiment of the present invention, the resin has a cyclic molecular structure. As resins having such a cyclic molecular structure, epoxy resins, polycarbonate resins, and polyphenylene sulfide resins are preferably used. The above resins can be used alone or in combination of two or more. The above resins may also be cured with a curing agent.

[0049] Furthermore, the material constituting the filler is not particularly limited, and examples thereof include glass, carbon, calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, titanium oxide, alumina, zinc oxide, silica (silicon dioxide), kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, polyester, polyurethane, rubber, etc. Among these, from the viewpoint of processability, glass and silica are preferred, and silica is particularly preferred.

[0050] Examples of the shape of the filler include powder, spheres, fibers, and needles. Of these, from the viewpoint of processability, spheres and fibers are preferred, with spheres being more preferred. The size of the filler is not particularly limited. For example, when the filler is spherical, the average particle diameter is, for example, 0.01 to 50 μm, preferably 1.0 to 6.5 μm. When the filler is fibrous, the major axis is, for example, 100 to 300 μm, preferably 150 to 250 μm, and the minor axis is, for example, 1 to 30 μm, preferably 10 to 20 μm.

[0051] The above fillers can be used alone or in combination of two or more.

[0052] Furthermore, the polishing object may contain, as a polishing surface, materials other than the resin and filler, such as copper (Cu), aluminum (Al), tantalum (Ta), tantalum nitride (TaN), titanium (Ti), titanium nitride (TiN), nickel (Ni), ruthenium (Ru), cobalt (Co), tungsten (W), and tungsten nitride (WN).

[0053] The polishing target may be prepared from resin and filler, or may be prepared using commercially available products, such as the interlayer insulating material "Ajinomoto Build-up Film" (ABF) GX13, GX92, GX-T31, and GZ41 (all from Ajinomoto Fine-Techno Co., Ltd.), the glass fiber-reinforced polycarbonate (PC) resin "Panlite®" (all from Teijin Limited), GF-reinforced DURAFIDE® PPS, and GF / inorganic filler-reinforced DURAFIDE® PPS (all from Polyplastics Co., Ltd.).

[0054] <Polishing method> Another aspect of the present invention relates to a polishing method comprising a step of polishing an object to be polished using the above-mentioned polishing composition. Preferred examples of the object to be polished in this aspect are the same as those described in the description of [Object to be polished]. For example, it is preferable to polish an object to be polished that contains a resin and a filler on the polishing surface. That is, a preferred aspect of the polishing method according to the present invention comprises a step of polishing an object to be polished that contains a resin and a filler using the above-mentioned polishing composition.

[0055] Polishing an object to be polished using a polishing composition can be carried out using equipment and conditions commonly used for polishing. Common polishing equipment includes single-sided polishing equipment and double-sided polishing equipment. In single-sided polishing equipment, the object to be polished is generally held using a holder called a carrier, and while a polishing composition is supplied from above, a platen with a polishing pad attached is pressed against one side of the object to be polished and the platen is rotated to polish one side of the object to be polished. In double-sided polishing equipment, the object to be polished is generally held using a holder called a carrier, and while a polishing composition is supplied from above, a platen with a polishing pad attached is pressed against the opposite side of the object to be polished, and the plates are rotated in relative directions to polish both sides of the object to be polished. During this process, polishing is achieved by the physical action of friction between the polishing pad and polishing composition and the object to be polished, and the chemical action of the polishing composition on the object to be polished. Porous materials such as nonwoven fabrics, polyurethane, and suede can be used as the polishing pad without any particular restrictions. It is preferable that the polishing pad be treated to allow the polishing liquid to accumulate.

[0056] Examples of polishing conditions include the polishing load, platen rotation speed, carrier rotation speed, flow rate of the polishing composition, and polishing time. There are no particular limitations on these polishing conditions. However, for example, the polishing load (polishing pressure) is preferably 0.1 psi (0.69 kPa) or more and 10 psi (69 kPa) or less per unit area of ​​the workpiece to be polished, more preferably 0.5 psi (3.5 kPa) or more and 8.0 psi (55 kPa) or less, and even more preferably 1.0 psi (6.9 kPa) or more and 6.0 psi (41 kPa) or less. Generally, the higher the load, the higher the frictional force caused by the abrasive grains, improving the mechanical processing force and increasing the polishing rate. Within this range, a sufficient polishing rate can be achieved, and damage to the workpiece to be polished due to the load and the occurrence of defects such as scratches on the surface can be suppressed. The platen rotation speed and carrier rotation speed are preferably 10 rpm (0.17 s -1 )~500rpm(8.3s -1) is preferable. The supply amount of the polishing composition is only required to be a supply amount (flow rate) that covers the entire object to be polished, and may be adjusted depending on conditions such as the size of the object to be polished. The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying the polishing composition using a pump or the like is used. In addition, the processing time is not particularly limited as long as it is a time that can obtain the desired processing result, but it is preferable to use a shorter time due to the high polishing rate.

[0057] Yet another aspect of the present invention relates to a method for producing a polished object, comprising a step of polishing an object by the above-described polishing method. Preferred examples of the object to be polished according to this aspect are the same as those described in the description of [Object to be polished]. A preferred example is a method for producing an electronic circuit board, comprising polishing an object to be polished containing resin and metal by the above-described polishing method. [Example]

[0058] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0059] <Methods for measuring physical properties> [Average particle size of alumina particles] The alumina particles (first abrasive grains) were measured using a particle size distribution analyzer (Microtrac particle size distribution analyzer MT3300EX II, manufactured by Microtrac-Bell Corporation) to determine the volumetric particle size distribution. In the obtained particle size distribution, the particle size at which the cumulative frequency from the small particle size side is 50% was determined as the average particle size (D 50 ) was decided.

[0060] [Average particle size of colloidal silica particles] The colloidal silica particles (secondary abrasive grains) were measured using a particle size distribution analyzer (Microtrac-Bell Corporation, nanoparticle size analyzer NANOTRAC WAVE II UPA-UT151) to determine the volumetric particle size distribution. In the obtained particle size distribution, the particle size at which the cumulative frequency from the small particle size side reaches 50% was determined as the average particle size (D 50 ) was decided.

[0061] [Average major axis, average minor axis, aspect ratio of colloidal silica particles] For colloidal silica particles (secondary abrasive grains), 100 samples were randomly selected from images taken with a scanning electron microscope (SEM) (Hitachi High-Tech Corporation, product name: SU8000), and the long and short diameters of each were measured to calculate the average long diameter (μm) and average short diameter (μm). Next, using the obtained values ​​of the average long diameter (μm) and average short diameter (μm), the average long diameter was divided by the average short diameter to calculate the aspect ratio of the colloidal silica particles (average long diameter / average short diameter).

[0062] [pH] The pH value of the polishing composition was confirmed using a pH meter (manufactured by Horiba Ltd., model number: LAQUA (registered trademark)).

[0063] [Examples 1 to 14 and Comparative Examples 1 to 14] Polishing compositions were prepared by stirring and mixing the first abrasive grains and second abrasive grains or first abrasive grains shown in Table 1, and water in the amounts shown in Table 1 (mixing temperature: about 25°C, mixing time: about 30 minutes). In Examples 1 to 8 and 10 to 14 and Comparative Examples 1 to 14, the pH was adjusted to the pH shown in Table 1 using a 30% by mass aqueous solution of malic acid. In Example 9, the pH was adjusted to the pH shown in Table 1 using a 48% by mass aqueous solution of potassium hydroxide. "Alumina" in Table 1 below refers to α-alumina particles.

[0064] In Table 1 below, the colloidal silica particles having an average particle diameter of 0.08 μm are produced by the sodium silicate method, and the average particle diameter (D 50 ) is 0.08 μm, and the span value [(D90 -D 10 ) / D 50 The colloidal silica particles with an average particle size of 0.02 μm were produced by the sodium silicate method, and the average particle size (D 50 ) is 0.02 μm, and the span value [(D 90 -D 10 ) / D 50 The colloidal silica particles having an average particle size of 0.05 μm were produced by the sodium silicate method, and the average particle size (D 50 ) is 0.05 μm, and the span value [(D 90 -D 10 ) / D 50 The colloidal silica particles having an average particle size of 0.2 μm were produced by the alkoxide method, and the average particle size (D 50 ) is 0.2 μm, and the span value [(D 90 -D 10 ) / D 50 ] was 0.98.

[0065] The polishing rate and surface roughness (Ra) of the polishing compositions obtained above were evaluated according to the methods described below in [Polishing Rate (Polishing Speed) 1] and [Surface Roughness (Ra)]. The results are shown in Table 1 below. In Table 1 below, "mixing ratio" refers to the mixing mass ratio of the first abrasive grains to the second abrasive grains (addition amount of first abrasive grains (mass%) / addition amount of second abrasive grains (mass%)). Furthermore, "particle size ratio" refers to the average particle size ratio of the first abrasive grains to the second abrasive grains (average particle size (μm) of the first abrasive grains / average particle size (μm) of the second abrasive grains). "Increase rate" is a value calculated according to the following formula, and indicates the increase rate (%) of the polishing rate relative to an equal amount of alumina alone. For example, the increase rate for Example 1 is 250(%) (=[(0.49-0.14)×100] / 0.14) because the polishing rate of the polishing composition of Example 1 is 0.49 and the polishing rate of the polishing composition of Comparative Example 1 containing only an equal amount of alumina is 0.14.

[0066]

number

[0067] <Evaluation> [Polishing rate (polishing speed) 1] The object to be polished was prepared by mixing epoxy resin and filler (spherical silica, average particle size = 1.0 μm) so that the filler content was 70 mass % (object to be polished 1; specific gravity: 1.9 g / cm 3 Subsequently, each polishing composition was used to polish an object (substrate) using the polishing apparatus and under the polishing conditions described below, and the polishing rate (polishing rate) of the object 1 was evaluated according to the polishing rate evaluation method described below.

[0068] (Polishing equipment and polishing conditions) Polishing device: Small desktop polishing machine (Engis Japan Co., Ltd. EJ380IN) Surface plate diameter: 380 [mm] Polishing pad: Hard polyurethane pad (Nitta DuPont IC1010) Platen rotation speed: 90 rpm Head (carrier) rotation speed: 90 rpm Polishing pressure: 3.0 [psi] (210 [g / cm 2 ) Flow rate of polishing composition: 20 [ml / min] Polishing time: 5 min.

[0069] (Method for evaluating polishing speed) 1. Using an analytical balance XS205 (Mettler-Toledo), the mass of the object to be polished was measured before and after polishing, and the mass change ΔM [kg] of the object to be polished before and after polishing was calculated from the difference between these values; 2. The change in mass of the object to be polished before and after polishing, ΔM (kg), is divided by the specific gravity of the object to be polished (specific gravity of the material to be polished) to obtain the change in volume of the object to be polished before and after polishing, ΔV (m 3 ] was calculated; 3. Volume change of the object to be polished before and after polishing ΔV [m 3 ] is the area of ​​the polishing surface of the object to be polished S [m 2 ] to calculate the thickness change Δd [m] of the polished object before and after polishing; 4. The thickness change Δd (m) of the workpiece before and after polishing was divided by the polishing time t (min) and then converted to μm / min. This value was taken as the polishing rate v (μm / min). Note that a higher polishing rate is preferable, but a polishing rate of 0.3 μm / min or more is acceptable, and a rate of over 0.45 μm / min is desirable.

[0070] Surface roughness (Ra) The surface roughness Ra of the polished object (epoxy resin) used in the evaluation of the polishing rate after polishing was measured using a non-contact surface profilometer (laser microscope, VK-X200, manufactured by Keyence Corporation). The surface roughness Ra is a parameter indicating the average amplitude of the roughness curve in the height direction, and indicates the arithmetic mean of the height of the surface of the polished object within a certain field of view. The measurement range (field of view) of the non-contact surface profilometer was 95 μm × 72 μm. The smaller the surface roughness (Ra), the better, but a value of less than 100 nm is acceptable, and a value of less than 50 nm is desirable.

[0071] [Table 1-1]

[0072] [Table 1-2]

[0073] As shown in Table 1, it was demonstrated that the use of the polishing composition of the present invention can reduce surface roughness while maintaining a high polishing rate (removal speed). On the other hand, when the polishing compositions of Comparative Examples 1-2 and 7-9 containing only alumina particles or the polishing compositions of Comparative Examples 11-14 containing only colloidal silica particles were used, at least one of the polishing rate (removal speed) and surface roughness was inferior. Furthermore, when the polishing compositions of Comparative Examples 3-6 and 14, which satisfy the abrasive grain size (average particle diameter) of the present invention but use abrasive grain combinations outside the scope of the present invention, were used, at least one of the polishing rate (removal speed) and surface roughness was inferior.

[0074] [Examples 15 to 16, Comparative Examples 15 to 16] A polishing composition was prepared in the same manner as in Example 1. Separately, a polishing composition was prepared in the same manner as in Comparative Example 1 above.

[0075] For each of the polishing compositions obtained above, the polishing rate was evaluated for different objects to be polished according to the following method. Furthermore, for each of the polishing compositions obtained above, the surface roughness (Ra) was evaluated in the same manner as in the above [Surface roughness (Ra)]. The results are shown in Table 2 below. Table 2 below also lists the results of Example 1 and Comparative Example 1.

[0076] <Evaluation> [Polishing rate (polishing speed)2] The object to be polished was prepared by mixing polycarbonate resin and filler (glass fiber, major axis = 218 μm, minor axis = 13 μm) so that the filler content was 30 mass % (object to be polished 2; specific gravity: 1.54 g / cm 3 ). Next, the polishing rate (removal rate) of the object to be polished 2 was evaluated using the polishing composition in the same manner as in the above [Polishing Rate (Removal Speed) 1], except that the object to be polished 2 prepared above was used instead of the object to be polished 1 (Example 15, Comparative Example 15). In this evaluation, the higher the polishing rate, the better, but a rate exceeding 0.50 μm / min is acceptable, and 0.65 μm / min or higher is desirable. Furthermore, the smaller the surface roughness (Ra), the better, but a rate less than 500 nm is acceptable, and a rate less than 200 nm is desirable.

[0077] [Polishing rate (polishing speed)3] A mixture of polyphenylene sulfide resin and filler (spherical silica, average particle diameter = 6.5 μm) was prepared as the polishing object so that the filler content was 50 mass % (polishing object 3; specific gravity: 1.78 g / cm 3). Next, the polishing rate (removal rate) of the object to be polished 3 was evaluated using the polishing composition in the same manner as in the above [Polishing Rate (Removal Speed) 1], except that the object to be polished 3 prepared above was used instead of the object to be polished 1 (Example 16, Comparative Example 16). In this evaluation, the higher the polishing rate, the better, but a rate exceeding 0.10 μm / min is acceptable, and 0.11 μm / min or higher is desirable. Furthermore, the smaller the surface roughness (Ra), the better, but a rate less than 250 nm is acceptable, and a rate less than 200 nm is desirable.

[0078] [Table 2]

[0079] As shown in Table 2, by using the polishing composition of the present invention, it was shown that the surface roughness can be reduced while maintaining a high polishing rate for objects to be polished containing various resins and fillers.

[0080] This application is based on Japanese Patent Application No. 2020-209498, filed on December 17, 2020, the disclosure of which is incorporated by reference in its entirety.

Claims

1. A polishing composition used for polishing an object to be polished, which contains alumina particles, colloidal silica particles, and a dispersion medium, and which contains a resin and a filler, The alumina particles have an average particle size of less than 2.8 μm, the average particle size of the colloidal silica particles is smaller than the average particle size of the alumina particles; the colloidal silica particles have a span value [(D 90 -D 10 ) / D 50 ] of 0.50 or more and 0.95 or less, The D 90 is a particle size at which the cumulative frequency from the small particle size side in the volume-based particle size distribution is 90%; D10 is the particle size at which the cumulative frequency from the small particle size side in the volume-based particle size distribution is 10%; The D50 is a particle size at which the cumulative frequency from the small particle size side in the volume-based particle size distribution is 50%. Polishing composition.

2. 2. The polishing composition according to claim 1, wherein the average particle size of the colloidal silica particles is 0.02 μm or more and less than 0.20 μm.

3. 3. The polishing composition according to claim 1, wherein the alumina particles have an average particle size of more than 0.2 μm and less than 1.2 μm.

4. 4. The polishing composition according to claim 1, wherein the ratio of the average particle size of the alumina particles to the average particle size of the colloidal silica particles is more than 1.5 and less than 20.

0.

5. 5. The polishing composition according to claim 1, wherein a mixing mass ratio of said alumina particles to said colloidal silica particles is 0.3 or more and less than 5.

0.

6. A polishing composition described in any one of claims 1 to 5, wherein the colloidal silica particles are colloidal silica produced by the sodium silicate method.

7. A polishing composition described in any one of claims 1 to 6, having a pH of 1 or more and 6 or less.

8. A polishing method comprising polishing an object to be polished containing a resin and a filler with the polishing composition according to any one of claims 1 to 7.

9. The method of claim 8 , wherein the resin has a cyclic molecular structure.

10. 10. The method of claim 8 or 9, wherein the filler is spherical.

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