Polishing method and method for manufacturing semiconductor component

Abstract

The present invention provides a polishing method capable of sufficiently suppressing the occurrence of polishing scratches while maintaining a sufficiently high polishing speed and selection ratio of an insulating film, and a method for manufacturing a semiconductor component using the polishing method. In this polishing method, a surface to be polished is brought into contact with a polishing pad while supplying a polishing agent containing abrasive grains and water, the polishing pad has a polishing layer containing a urethane resin containing constituent units derived from methylene diphenyl diisocyanate (MDI), and polishing is performed by the relative movement of the polishing agent and the polishing pad, the urethane resin containing constituent units derived from methylene diphenyl diisocyanate (MDI), and the urethane resin containing constituent units derived from methylene diphenyl diisocyanate (MDI). The content of the methylene diphenyl diisocyanate is 30% by mass or more with respect to the total mass of the polishing layer, the Shore A hardness of the polishing layer is 90 degrees or less, the water absorption of the polishing layer is 5% or more, and the surface to be polished includes an insulating film.

Description

Technical Field

[0001] The present invention relates to a polishing method and a method for manufacturing a semiconductor component. Background Art

[0002] With the high integration and high functionality of semiconductor integrated circuits, the development of microfabrication technologies for miniaturization and high density of semiconductor elements has been continuously promoted. Conventionally, in the manufacture of semiconductor integrated circuit devices (hereinafter, also referred to as semiconductor devices), in order to prevent problems such as unevenness (step difference) on the layer surface exceeding the depth of focus of lithography and insufficient resolution, chemical mechanical polishing (hereinafter referred to as CMP) is used to planarize the interlayer insulating film, buried wiring, etc.

[0003] In addition, in recent years, in the manufacture of semiconductor devices, in order to promote further miniaturization of semiconductor elements, a separation method using shallow trenches with a small element separation width (Shallow Trench Isolation: hereinafter referred to as STI) has been introduced.

[0004] STI is a method of forming electrically insulating element regions by forming trenches (grooves) in a silicon substrate and burying an insulating film in the trenches. Refer to Figure 1A , Figure 1B An example of STI will be described. In this example, first, as Figure 1A shown, after masking the element regions of the silicon substrate 1 with a silicon nitride film 2 or the like, trenches 3 are formed in the silicon substrate 1, and an insulating film such as a silicon oxide film 4 is deposited so as to fill the trenches 3. Next, by CMP, while leaving the silicon oxide film 4 in the trenches 3 as recesses, the silicon oxide film 4 on the silicon nitride film 2 as a protrusion is polished and removed. As Figure 1B shown, an element isolation structure in which the silicon oxide film 4 is buried in the trenches 3 is obtained. In addition, although not shown, the silicon nitride film 2 is sometimes removed.

[0005] Patent Document 1 discloses a polishing method in which while supplying an abrasive to between a film to be polished and a polishing pad, the film to be polished is polished, and abrasive grains such as tetravalent cerium oxide particles and a polishing pad having a Shore D hardness of 41 to 59 are used. In the examples of Patent Document 1, it is shown that in the combination of a polishing pad having a Shore D hardness of less than 41 and abrasive grains, the polishing rate of SiO2 becomes low.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-153782 Summary of the Invention

[0009] From the viewpoints of improving the productivity of semiconductor elements and the like, it is required to maintain a sufficiently high polishing rate and selectivity of the insulating film (for example, the ratio of the polishing rate of silicon oxide to the polishing rate of silicon nitride, the ratio of the polishing rate of silicon oxide to the polishing rate of polysilicon) in the above CMP, while sufficiently suppressing the generation of polishing scratches.

[0010] However, generally, improving the polishing rate and selectivity of the insulating film and suppressing the generation of polishing scratches are in a trade-off relationship, and it is difficult to satisfy both at the same time.

[0011] In view of the above problems, the present disclosure provides a polishing method capable of maintaining a sufficiently high polishing rate and selectivity of the insulating film while sufficiently suppressing the generation of polishing scratches, and a method for manufacturing a semiconductor component using the polishing method.

[0012] The present disclosure provides a polishing method and a method for manufacturing a semiconductor component having the following configurations [1] to

[14] .

[0013] [1] A polishing method in which while supplying a polishing agent, a surface to be polished of a semiconductor substrate is brought into contact with a polishing pad, and polishing is performed by the relative movement of the two.

[0014] The polishing agent contains abrasive grains and water.

[0015] The polishing pad has a polishing layer containing a polyurethane resin.

[0016] The Shore A hardness of the polishing layer is 90 degrees or less.

[0017] The water absorption rate of the polishing layer is 5% or more.

[0018] The polyurethane resin contains a structural unit derived from methylene diphenyl diisocyanate (MDI).

[0019] The content of the methylene diphenyl diisocyanate is 30% by mass or more based on the total mass of the polishing layer.

[0020] The surface to be polished includes an insulating film.

[0021] [2] The polishing method according to [1], wherein the abrasive grains include at least one selected from silica particles, alumina particles, zirconia particles, ceria particles, titanium dioxide particles, germanium oxide particles, cerium hydroxide particles, and composite particles thereof.

[0022] [3] The polishing method according to [1] or [2], wherein the abrasive grains include ceria particles.

[0023] [4] The grinding method according to any one of [1] to [3], wherein the content of the abrasive grains is 0.01% by mass to 10.0% by mass relative to the total mass of the abrasive.

[0024] [5] The grinding method according to any one of [1] to [4], wherein the abrasive further contains a dispersant.

[0025] [6] The grinding method according to [5], wherein the dispersant contains at least one selected from an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

[0026] [7] The grinding method according to [5] or [6], wherein the content of the dispersant is 0.0001% by mass to 0.3% by mass relative to the total mass of the abrasive.

[0027] [8] The grinding method according to any one of [1] to [7], wherein the grinding layer is a suede type.

[0028] [9] The grinding method according to any one of [1] to [8], wherein the grinding layer is formed by a wet film-forming method.

[0029]

[10] The grinding method according to any one of [1] to [9], wherein the grinding layer is a porous layer having a plurality of pores in a polyurethane resin part,

[0030] The polyurethane resin part has a three-dimensional network structure, and the three-dimensional network structure includes a network-shaped polyurethane resin and fine pores.

[0031]

[11] The grinding method according to

[10] , wherein when the average pore diameter of the plurality of pores in the polyurethane resin part is set as D1 and the average pore diameter of the fine pores is set as D2, D1 / D2 is 5.0 to 200.

[0032]

[12] The grinding method according to any one of [1] to

[11] , wherein the polyurethane resin contains a structural unit derived from a polyether polyol or a polyester polyol.

[0033]

[13] The grinding method according to any one of [1] to

[12] , wherein the insulating film contains at least one selected from silicon oxide, silicon nitride, and polysilicon.

[0034]

[14] A method for manufacturing a semiconductor component, wherein a semiconductor component is obtained by singulating a semiconductor substrate, and the semiconductor substrate has a ground surface ground by the grinding method according to any one of [1] to

[13] .

[0035] According to the present disclosure, a polishing method capable of maintaining a sufficiently high polishing rate and selectivity of an insulating film while sufficiently suppressing the generation of polishing scratches, and a method for manufacturing a semiconductor component using the polishing method can be provided. Description of the Drawings

[0036] Figure 1A FIG. is a cross-sectional view showing an example of a polishing method and showing a state before polishing of an object to be polished.

[0037] Figure 1B FIG. is a cross-sectional view showing an example of a polishing method and showing a state after polishing of an object to be polished.

[0038] Figure 2 FIG. is a schematic view showing an example of a polishing apparatus.

[0039] Figure 3 FIG. is a schematic view showing an example of a cross-section of a polishing layer.

[0040] Figure 4 FIG. is a schematic view showing an example of the surface of a polyurethane resin. Detailed Embodiments

[0041] Hereinafter, embodiments of the present disclosure will be described. For clarity of description, the following description and drawings are appropriately simplified. In addition, for the purpose of illustration, the scales of the respective components in the drawings are sometimes significantly different.

[0042] It should be noted that in the present disclosure, the "surface to be polished" refers to the surface of the object to be polished, for example, the surface. In this specification, the surface at an intermediate stage in the polishing process is also included in the "surface to be polished".

[0043] In the present disclosure, the "polishing layer" refers to the layer that constitutes the polishing pad and contacts the object to be polished.

[0044] In the present disclosure, "(meth)acrylic acid" refers to a general term for acrylic acid and methacrylic acid, and the same applies to "(meth)acrylonitrile" and the like.

[0045] In addition, unless otherwise specified, "~" indicating a numerical range includes the numerical values described before and after it as the lower limit value and the upper limit value.

[0046] ·Polishing Method

[0047] The polishing method of the present disclosure is a polishing method in which while supplying a polishing agent, the surface to be polished of the semiconductor substrate is brought into contact with a polishing pad, and polishing is performed by the relative movement of the two.

[0048] The above-mentioned polishing agent contains abrasive grains and water.

[0049] The above-mentioned polishing pad has a polishing layer containing a polyurethane resin,

[0050] The Shore A hardness of the above-mentioned polishing layer is 90 degrees or less,

[0051] The above-mentioned polyurethane resin contains structural units derived from methylene diphenyl diisocyanate (MDI),

[0052] The content of the above-mentioned methylene diphenyl diisocyanate is 30% by mass or more based on the total mass of the above-mentioned polishing layer,

[0053] The surface to be polished contains an insulating film.

[0054] In this polishing method, by using the above-mentioned specific polyurethane resin as the polishing pad and combining it with a polishing agent containing abrasive grains, the polishing rate of the surface to be polished, particularly the surface containing an insulating film, is improved. Hereinafter, each component will be described.

[0055] [Polishing agent]

[0056] In this polishing method, the polishing agent contains at least abrasive grains and water, and other components may be further contained within the scope of achieving the effects of the present invention. Hereinafter, each component that can be contained in this polishing agent will be described.

[0057] <Abrasive grains>

[0058] In this polishing method, the abrasive grains can be appropriately selected from the abrasive grains used as CMP abrasive grains for use. As the abrasive grains, for example, at least one selected from silica particles, alumina particles, zirconia particles, cerium compound particles (such as cerium oxide particles, cerium hydroxide particles), titanium dioxide particles, germanium oxide particles, and core-shell type particles having these as core particles can be cited. As the above-mentioned silica particles, colloidal silica, fumed silica, etc. can be cited. As the above-mentioned alumina particles, colloidal alumina can also be used.

[0059] The above-mentioned core-shell type particles are composed of core particles (such as silica particles, alumina particles, zirconia particles, cerium compound particles, titanium dioxide particles, germanium oxide particles) and a thin film covering the surface of the core particles.

[0060] As the material of the above-mentioned thin film, for example, at least one selected from oxides such as silica, alumina, zirconia, cerium oxide, titanium dioxide, germanium oxide, iron oxide, manganese oxide, zinc oxide, yttrium oxide, calcium oxide, magnesium oxide, lanthanum oxide, strontium oxide can be cited. In addition, the above-mentioned thin film can be formed of nanoparticles composed of a plurality of these oxides.

[0061] The particle size of the above-mentioned core particles is preferably 0.01 μm to 0.5 μm, more preferably 0.03 μm to 0.3 μm.

[0062] The particle size of the above-mentioned nanoparticles only needs to be smaller than that of the above-mentioned core particles, preferably 1 nm to 100 nm, more preferably 5 nm to 80 nm.

[0063] As the abrasive grains, among the above, from the aspect of excellent polishing rate of the insulating film, silicon dioxide particles, alumina particles or cerium compound particles are preferred, and cerium compound particles are more preferred. In the case where the surface to be polished contains an insulating film (especially a silicon oxide film), from the aspect of obtaining a high polishing rate, cerium oxide particles are further preferred. In the case of core-shell type particles, the thin film preferably contains silicon dioxide, alumina or a cerium compound, and more preferably contains cerium oxide. The abrasive grains can be used alone or in combination of two or more.

[0064] The content of cerium oxide relative to the total mass of the abrasive grains is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100%. If the content of cerium oxide relative to the total mass of the abrasive grains is 70% by mass or more, a high value is easily obtained as the polishing rate of the insulating film (especially a silicon oxide film).

[0065] The cerium oxide particles can be appropriately selected and used from known cerium oxide particles. For example, cerium oxide particles manufactured by the methods described in Japanese Patent Laid-Open No. 11-12561, Japanese Patent Laid-Open No. 2001-35818, and Japanese Patent Publication No. 2010-505735 can be cited. Specifically, cerium oxide particles obtained by adding an alkali to an aqueous solution of ammonium cerium(IV) nitrate to prepare a cerium hydroxide gel, filtering, washing, and calcining it; cerium oxide particles obtained by crushing high-purity cerium carbonate, calcining it, and further crushing and classifying it; cerium oxide particles obtained by chemically oxidizing a cerium(III) salt in a liquid, etc. can be cited.

[0066] The cerium oxide particles may contain impurities other than cerium oxide. The content of cerium oxide in one cerium oxide particle is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% or more, and most preferably 100% (excluding impurities). If the content of cerium oxide in the cerium oxide particles is 80% by mass or more, it is easy to increase the polishing rate of the insulating film.

[0067] The average particle size of the abrasive grains is preferably 0.01 μm to 0.5 μm, more preferably 0.03 μm to 0.3 μm. If the average particle size is 0.5 μm or less, the mechanical action imparted to the surface to be polished becomes smaller, so the generation of polishing scratches such as scratches on the surface to be polished is suppressed. In addition, if the average particle size is 0.01 μm or more, the aggregation of the inhaled abrasive grains is suppressed, the storage stability of the polishing agent is excellent, and the polishing rate is also excellent.

[0068] It should be noted that the abrasive grains exist in the form of agglomerated particles (secondary particles) formed by the aggregation of primary particles in the liquid. Therefore, the above-mentioned average particle size is the average secondary particle size. The average secondary particle size is measured using a particle size distribution meter such as a laser diffraction / scattering type with a dispersion liquid dispersed in a dispersion medium such as pure water.

[0069] The lower limit value of the content of the abrasive grains is preferably 0.01% by mass, more preferably 0.05% by mass, further preferably 0.1% by mass, and particularly preferably 0.15% by mass with respect to the total mass of the abrasive. If the content of the abrasive grains is above the above lower limit value, an excellent polishing rate with respect to the surface to be polished can be obtained. On the other hand, the upper limit value of the content of the abrasive grains is preferably 10.0% by mass, more preferably 8.0% by mass, further preferably 5.0% by mass, particularly preferably 2.0% by mass, particularly more preferably 1.0% by mass, extremely preferably 0.8% by mass, and most preferably 0.5% by mass with respect to the total mass of the abrasive. If the content ratio of the abrasive grains is below the above upper limit value, the aggregation of the abrasive grains can be suppressed, and the increase in the viscosity of this abrasive can be suppressed, and the operability is excellent.

[0070] <Water>

[0071] This abrasive contains water as a medium for dispersing the abrasive grains (A). The type of water is not particularly limited, and pure water, ultrapure water, ion-exchanged water, etc. are preferably used in consideration of the influence on other components, prevention of the mixing of impurities, and the influence on pH, etc.

[0072] <Additives>

[0073] This abrasive may further contain various additives. Examples of such additives include pH adjusters, dispersants, water-soluble polymers, anti-aggregation agents, lubricants, viscosity imparting agents, viscosity regulators, preservatives, etc., and two or more additives may be contained.

[0074] (pH Adjuster)

[0075] In order to adjust the pH to a specified value, a pH adjuster may be contained. As the pH adjuster, it can be appropriately selected and used from acidic compounds, alkaline compounds, amphoteric compounds such as amino acids, and their salts.

[0076] Examples of acidic compounds include inorganic acids, organic acids, or their salts. Examples of inorganic acids include nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, etc., and their ammonium salts, sodium salts, potassium salts, etc. can also be used.

[0077] Examples of organic acids include compounds having a carboxyl group, a sulfo group, or a dioxophosphoryl group as an acidic group, and their ammonium salts, sodium salts, potassium salts, etc.

[0078] As organic acids having a carboxyl group, examples include alkyl monocarboxylic acids such as formic acid, acetic acid, and propionic acid;

[0079] Carboxylic acids having a heterocycle such as 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, 2,3-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, pyrazinecarboxylic acid, 2,3-pyrazinedicarboxylic acid, 2-quinolinecarboxylic acid, pyroglutamic acid, picolinic acid, DL-pipecolic acid, 2-furancarboxylic acid, 3-furancarboxylic acid, tetrahydrofuran-2-carboxylic acid, tetrahydrofuran-2,3,4,5-tetracarboxylic acid;

[0080] Carboxylic acids having an alicyclic ring such as cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, cyclohexylcarboxylic acid;

[0081] Carboxylic acids having an amino group such as alanine, glycine, glycylglycine, aminobutyric acid, N-acetylglycine, N,N-bis(2-hydroxyethyl)glycine, N-(tert-butoxycarbonyl)glycine, proline, trans-4-hydroxy-L-proline, phenylalanine, sarcosine, hydantoinic acid, creatine, N-[tris(hydroxymethyl)methyl]glycine, glutamic acid, aspartic acid;

[0082] Carboxylic acids having a hydroxyl group such as lactic acid, malic acid, citric acid, tartaric acid, glycolic acid, gluconic acid, salicylic acid, 2-hydroxyisobutyric acid, glyceric acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid;

[0083] Carboxylic acids having a keto group (keto acids) such as pyruvic acid, acetoacetic acid, levulinic acid;

[0084] Dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, phthalic acid, etc.

[0085] When using an acid as a pH regulator in this abrasive, an inorganic acid is preferred, and among them, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid and their ammonium salts, sodium salts, and potassium salts are preferred.

[0086] As basic compounds, examples include ammonia, sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium carbonate, sodium carbonate, ammonium carbonate; quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; amino alcohols such as monoethanolamine, diethanolamine, and triethanolamine.

[0087] In addition, as amphoteric compounds, examples include glycine, alanine, and phenylalanine, etc.

[0088] The pH adjuster can be used alone or in combination of two or more. The pH of this abrasive is preferably 3.0 to 12.0, more preferably 3.5 to 11.5. By adjusting the pH within the above range, aggregation of abrasive grains can be inhibited, and the polishing rate and selectivity of the insulating film are excellent.

[0089] The content ratio of the pH adjuster can be appropriately adjusted so as to achieve the above pH. As an example, it can be 0.005% by mass to 2.0% by mass, preferably 0.01% by mass to 1.5% by mass, more preferably 0.01% by mass to 0.3% by mass, relative to the whole of this abrasive.

[0090] (Dispersant)

[0091] In order to improve the dispersibility of abrasive grains, a dispersant can be contained in this abrasive. As the dispersant, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be cited, and one or two or more of these can be used.

[0092] As the anionic surfactant, an organic acid having two or more carboxyl groups or carboxylate groups is preferred, and at least one selected from polymers of unsaturated carboxylic acids, copolymers of unsaturated carboxylic acids and monomers without carboxyl groups, partial esters of the polymer or copolymer, and salts thereof is more preferred.

[0093] As the unsaturated carboxylic acid, unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, etc. can be cited. Specifically, as the unsaturated monocarboxylic acid, acrylic acid, methacrylic acid, crotonic acid, etc. can be cited. Among these, acrylic acid is preferred.

[0094] As the unsaturated dicarboxylic acid, specifically, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, 2 - allylmalonic acid, isopropylidenesuccinic acid, etc. can be cited, and they can also be in the form of acid anhydrides. Among these, at least one selected from maleic acid, maleic anhydride, fumaric acid, and itaconic acid is preferred, and maleic acid, maleic anhydride, and fumaric acid are particularly preferred from the viewpoint of polymerizability.

[0095] As the polymer of unsaturated carboxylic acid, it can be a homopolymer obtained by polymerizing one unsaturated carboxylic acid or a copolymer combining two or more. Specifically, polyacrylic acid, polymaleic acid, polyfumaric acid, polymethacrylic acid, polyitaconic acid, polycrotonic acid, acrylic acid / maleic acid copolymer, acrylic acid / methacrylic acid copolymer, acrylic acid / fumaric acid copolymer, maleic acid / fumaric acid copolymer, etc. can be cited.

[0096] The organic acid may also be a copolymer of an unsaturated carboxylic acid and a monomer not containing a carboxylic acid group. Examples of the monomer not containing a carboxylic acid group include sulfonic acid monomers, vinyl ester monomers, aromatic vinyl monomers, α-olefins, vinyl ether monomers, allyl compounds, N-alkyl substituted (meth)acrylamide, and nitrile monomers. Here, (meth)acrylamide is a general term for acrylamide and methacrylamide, and the same explanation applies to other compounds.

[0097] Examples of sulfonic acid monomers include 2-acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, allylsulfonic acid, and methacrylic acid; examples of vinyl ester monomers include vinyl acetate and vinyl propionate; examples of aromatic vinyl monomers include styrene, methylstyrene, and vinylnaphthalene; examples of α-olefins include isobutylene and diisobutylene; examples of vinyl ester monomers include vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; examples of allyl compounds include vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether. Examples of the N-alkyl-substituted (meth)acrylamide include allyl alcohol, allyl ethyl ether, allyl butyl ether, allyl glycidyl ether or allyl alcohol alkylene oxide (hereinafter also referred to as AO) adducts (it should be noted that AO adducts include ethylene oxide (hereinafter referred to as EO) adducts and propylene oxide (hereinafter also referred to as PO) adducts); examples of the N-alkyl-substituted (meth)acrylamide include N-methyl (meth)acrylamide and N-ethyl (meth)acrylamide; examples of the nitrile monomer include (meth)acrylonitrile and the like.

[0098] In addition, as the monomer not containing carboxylic acid group, unsaturated carboxylic acid esters such as (meth) acrylate monomers can be used. In this way, by copolymerizing unsaturated carboxylic acid and unsaturated carboxylic acid ester, a partial esterification product of the polymer of unsaturated carboxylic acid can be obtained. It should be noted that the partial esterification product of the polymer of unsaturated carboxylic acid can be obtained by partially esterifying the polymer of unsaturated carboxylic acid by a known method. Similarly, by copolymerizing unsaturated carboxylic acid, unsaturated carboxylic acid ester and monomers other than them, a partial esterification product of a copolymer of unsaturated carboxylic acid and a monomer not containing carboxylic acid group can be obtained.

[0099] Unsaturated carboxylic acid esters are, for example, unsaturated carboxylic acid groups (—C(═O)—OH) converted to —C(═O)—O—R 1 (R 1 is a monovalent substituent). 1 Preferably, it is a saturated hydrocarbon group having 1 to 50 carbon atoms, which may have an oxygen atom between carbon atoms. 1More preferably, it is a substituted or unsubstituted saturated hydrocarbon group having 2 to 30 carbon atoms and may have an oxygen atom between carbon-carbon atoms, and further preferably a substituted or unsubstituted saturated hydrocarbon group having 5 to 20 carbon atoms and may have an oxygen atom between carbon-carbon atoms. The saturated hydrocarbon group may be linear, branched or cyclic, or may be a linear or branched chain containing a cyclic structure. Further, as substituents of the substituted saturated hydrocarbon group, hydroxyl group, epoxy group, amino group, etc. can be cited.

[0100] As R 1 , specifically, methyl group, ethyl group, propyl group, n-butyl group, 2-ethylhexyl group, lauryl group, 2-hydroxyethyl group, polyethylene glycol group, methoxypolyethylene glycol group, glycidyl group, dimethylaminoethyl group, diethylaminoethyl group, etc. can be cited. As the unsaturated carboxylic acid ester, (meth)acrylate is preferred.

[0101] The organic acids described above are organic acids having multiple carboxylic acid groups. The organic acid having a carboxylate group is an organic acid in which at least a part of the carboxylic acid groups of these organic acids is salified. As counter ions of the salts of the carboxylate group, for example, alkali metal salts such as sodium and potassium, alkaline earth metal salts such as magnesium and calcium, ammonium salts, amine salts, and organic amine salts can be cited. From the aspect of solubility in the water used for the abrasive, alkali metal salts such as sodium and potassium and ammonium salts are preferred. Ammonium salts are further preferred.

[0102] The polymers and copolymers of organic acids can be obtained by polymerizing the above-mentioned monomers alone or in appropriate combination using a known method. The weight average molecular weight of the organic acid is preferably 500 to 1,000,000, more preferably 1,000 to 20,000, and further preferably 2,000 to 10,000. If the weight average molecular weight of the organic acid is 500 or more, the state in which the organic acid is adsorbed on the surface of the cerium oxide particles and the surface to be polished including the silicon nitride film can be stably ensured. If the weight average molecular weight of the organic acid is 1,000,000 or less, the operability and the like are good. It should be noted that unless otherwise stated, the weight average molecular weight in this specification is the weight average molecular weight measured by a gel permeation chromatograph (GPC).

[0103] The proportion of the units of the unsaturated carboxylic acid in the organic acid is preferably 40 to 100 mol%, more preferably 50 to 100 mol%, further preferably 60 to 100 mol%, and particularly preferably substantially only the units of the unsaturated carboxylic acid. It should be noted that substantially only the units of the unsaturated carboxylic acid means that the proportion of the units of the unsaturated carboxylic acid in all units is 95 mol% or more, preferably 98 mol% or more.

[0104] The organic acid used in the present invention is preferably an organic acid substantially composed of only the units of the unsaturated carboxylic acid, more preferably an organic acid having acrylic acid as an essential constituent unit, and particularly preferably polyacrylic acid substantially composed of only the units of acrylic acid.

[0105] Examples of the cationic surfactant include diallyldimethylammonium chloride polymers, diallyldimethylammonium chloride·sulfur dioxide copolymers, diallyldimethylammonium chloride·acrylamide copolymers, diallyldimethylammonium chloride·maleic acid copolymers, maleic acid·diallyldimethylammonium ethyl sulfate·sulfur dioxide copolymers, and the like.

[0106] From the viewpoint of grinding the surface to be ground at a higher speed, the weight-average molecular weight of the above surfactant is preferably 10,000 to 100,000.

[0107] When a dispersant is used, the lower limit value of its content is preferably 0.0001% by mass, more preferably 0.001% by mass, and further preferably 0.01% by mass, relative to the total mass of the above abrasive. In addition, the upper limit value of its content is preferably 2.0% by mass, more preferably 1.5% by mass, further preferably 1.0% by mass, particularly preferably 0.5% by mass, extremely preferably 0.2% by mass, and most preferably 0.1% by mass, relative to the total mass of the above abrasive. If the content of the dispersant is within the above range, the surface to be ground can be ground at a higher speed.

[0108] (Lubricant)

[0109] In addition, the present abrasive may contain a lubricant. The lubricant is used as needed to improve the lubricity of the abrasive and the in-plane uniformity of the grinding speed, and examples thereof include water-soluble polymers such as polyethylene glycol and polyglycerol.

[0110] In the present abrasive, when the above additives are used, from the aspect of grinding the surface to be ground at a higher speed, the total content of the additives is preferably 0.01% by mass to 10.0% by mass, more preferably 0.01% by mass to 5.0% by mass, relative to the total mass of the above abrasive.

[0111] <Preparation method of abrasive>

[0112] The preparation method of the present abrasive can be appropriately selected from methods in which abrasive grains and various additives used as needed are uniformly dissolved or dispersed in water as a medium.

[0113] For example, the present abrasive can be prepared by separately preparing a dispersion of abrasive grains and an aqueous solution containing water and / or various additives (also referred to as an additive solution for abrasive), and mixing them. According to this method, the storage stability and transportation convenience of the above dispersion and additive solution for abrasive are excellent. The present abrasive can be prepared at the time of use by performing the above mixing in a grinding device.

[0114] It should be noted that in the case where the abrasive is prepared by mixing two liquids, namely, the dispersion liquid of abrasive grains and the additive liquid for abrasive, the concentration of the abrasive grains in the dispersion liquid can be concentrated to 2 to 100 times the concentration when the abrasive is used in advance, and then diluted with the additive liquid for abrasive to reach the specified concentration.

[0115] [Polishing pad]

[0116] In the polishing method of the present disclosure, the polishing pad is characterized in that it has a polishing layer containing a polyurethane resin, the polyurethane resin contains structural units derived from methylene diphenyl diisocyanate (MDI), and the content of the methylene diphenyl diisocyanate is 30% by mass or more based on the total mass of the polishing layer. By having 30% by mass or more of MDI in the polishing layer, it is possible to polish a surface to be polished, especially one containing an insulating film, at a higher speed.

[0117] It should be noted that in the polishing layer, MDI exists as a part of the polyurethane resin, and the content ratio (% by mass) is calculated as a value in terms of MDI.

[0118] The mechanism by which excellent polishing speed is obtained due to the polishing layer having 30% by mass or more of MDI is not yet clear, but it is considered that the heat and humidity resistance is improved by containing MDI. Generally, the polyurethane resin becomes soft due to long-term contact with water, frictional heat generated during polishing, etc. In contrast, it is speculated that when the polyurethane resin contains a certain amount or more of MDI, the heat and humidity resistance is improved due to its structure, and as a result, it is possible to suppress the polishing layer from becoming too soft and obtain excellent polishing speed. Furthermore, from the aspect of being able to suppress the polishing layer from becoming too soft, a relatively soft polishing layer with a Shore A hardness of 90 degrees or less can be selected as the polishing layer. As a result, while having excellent polishing speed, it is also possible to suppress the generation of polishing scratches.

[0119] The layer structure of the polishing pad is not particularly limited as long as the polishing layer can contact the surface to be polished. The polishing pad can be a single film composed only of the polishing layer, or a laminate having a polishing layer on a substrate.

[0120] The polishing layer has at least a polyurethane resin, and may further contain other components within the range of exerting the effects of the present invention. Hereinafter, each component that can be contained in the polishing layer will be described.

[0121] <Polyurethane resin>

[0122] A polyurethane resin is a resin having two or more urethane bonds. As the polyurethane resin, in addition to polymers of polyisocyanates and polyols or polyamines, and polymers of urethane prepolymers and polyols or polyamines, polymers obtained by polymerizing a conjugated diene, a dienophile, and a compound having a urethane bond or an isocyanate group through a Diels - Alder reaction are also known. From the viewpoints of chemical stability and the like, polymers of polyisocyanates and polyols, or polymers of urethane prepolymers and polyols are preferred. From the viewpoint of heat resistance, those not having a cyclohexene ring are preferred.

[0123] (Polyisocyanate)

[0124] A polyisocyanate is a compound having two or more isocyanate groups. The polyurethane resin of the present disclosure uses at least methylene diphenyl diisocyanate (MDI) as the polyisocyanate, and other polyisocyanates can also be used within the range that satisfies the above - mentioned content ratio.

[0125] Examples of MDI include 2,2'-methylene diphenyl diisocyanate, 2,4'-methylene diphenyl diisocyanate, 4,4'-methylene diphenyl diisocyanate (monomeric MDI), polymeric MDI (a mixture of monomeric MDI and polymethylene polyphenyl polyisocyanate), or modified products thereof (for example, carbodiimide - modified products, urethane - modified products (adducts), allophanate - modified products, urea - modified products, biuret - modified products, isocyanurate - modified products, oxazolidone - modified products), etc. Among these, 4,4'-methylene diphenyl diisocyanate and carbodiimide - modified MDI are preferred.

[0126] As other polyisocyanates, diisocyanates or triisocyanates are preferred, and diisocyanates are more preferred.

[0127] Specific examples of the diisocyanate include benzene diisocyanates (phenylenediisocyanates) such as benzene-1,3-diisocyanate, benzene-1,4-diisocyanate, and m-phenylene bis(1-methylethane-1,1-diyl) diisocyanate (TMXDI); toluene diisocyanates (toluene diisocyanate; TDI) such as toluene-2,4-diisocyanate, toluene-2,5-diisocyanate, toluene-2,6-diisocyanate, and toluene-3,5-diisocyanate; xylene diisocyanates such as 1,2-xylene-3,5-diisocyanate, 1,2-xylene-3,6-diisocyanate, 1,2-xylene-4,6-diisocyanate, 1,3-xylene-2,4-diisocyanate, 1,3-xylene-2,5-diisocyanate, 1,3-xylene-2,6-diisocyanate, 1,3-xylene-4,6-diisocyanate, 1,4-xylene-2,5-diisocyanate, and 1,4-xylene-2,6-diisocyanate; naphthalene-1,5-diisocyanate, 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl diphenylmethane-4,4'-diisocyanate, benzene dimethyl-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate (TMDI), propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, benzene dimethyl-1,4-diisothiocyanate, m-xylylene diisocyanate (XDI), ethylene diisothiocyanate, 1,4-cyclohexane diisocyanate (CHDI), 1,4-bis(isocyanatomethyl)cyclohexane, 1,2-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), isophorone diisocyanate (IPDI), norbornane diisocyanate (NBDI), and the like.

[0128] As specific examples of the triisocyanate, benzene-1,2,4-triisocyanate, benzene-1,2,5-triisocyanate, benzene-1,3,5-triisocyanate, toluene-2,3,5-triisocyanate, toluene-2,3,6-triisocyanate, toluene-2,4,5-triisocyanate, toluene-2,4,6-triisocyanate, toluene-3,4,6-triisocyanate, toluene-3,5,6-triisocyanate, 1,2-xylene-3,4,6-triisocyanate, 1,2-xylene-3,5,6-triisocyanate, 1,3-xylene-2,4,5-triisocyanate, 1,3-xylene-2,4,6-triisocyanate, 1,3-xylene-3,4,5-triisocyanate, 1,4-xylene-2,3,5-triisocyanate, 1,4-xylene-2,3,6-triisocyanate, etc. can be cited.

[0129] (Polyol)

[0130] The polyol is a compound having two or more hydroxyl groups. The polyol can be used alone one of the known polyols or in combination of two or more. As the polyol, diol, triol or tetrol is preferred, and diol is more preferred.

[0131] As specific examples of the diol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-octanediol, 3,6-dithia-1,8-octanediol, 1,8-octanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-bis(hydroxyethoxy)benzene, 1,4-benzenedimethanol, EO (ethylene oxide) adduct of bisphenol A, PO (propylene oxide) adduct of bisphenol A, etc. can be cited.

[0132] As specific examples of the triol, glycerol, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, etc. can be cited.

[0133] As specific examples of the tetrol, pentaerythritol, diglycerol, etc. can be cited.

[0134] In addition, prepolymer polyols (precursors of polyurethanes) can be used. Specifically, for example, polyester polyols obtained by the reaction of the above-mentioned low-molecular-weight polyols with polyacids (such as succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydrophthalic anhydride, etc.); polycaprolactone polyols obtained by the reaction of the above-mentioned low-molecular-weight polyols with ε-caprolactone; polycarbonate polyols obtained by the reaction of the above-mentioned low-molecular-weight polyols with diphenyl carbonate (for example, compounds obtained by reacting phosgene with alkylene glycols such as 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,10-decanediol, 1,5-pentanediol, etc.); polyether polyols linked with the above-mentioned low-molecular-weight polyols, etc. As the above polyether polyols, polyethylene glycol, polypropylene glycol, polypropylene glycol with EO (ethylene oxide) added at the end, polytetramethylene glycol, ethylene oxide-modified bisphenol A, etc. can be mentioned. For prepolymer polyols, it is preferred that the low-molecular-weight polyol is a diol. In addition, for prepolymer polyols, from the aspect of the polishing rate of the insulating film, among them, polyester polyols (for example, condensates of dicarboxylic acids such as adipic acid, azelaic acid, glutaric acid, phthalic acid, isophthalic acid, etc. and diols such as 1,6-hexanediol, neopentyl glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, ethylene glycol, propylene glycol, cyclohexanedimethanol, trimethylolpropane, glycerol, trihydroxyethyl isocyanurate, etc.) or polyether polyols (for example, poly(oxytetramethylene) glycol) are preferred.

[0135] In addition, as other prepolymer polyols, polyols in which the terminals or side chains of various polymers (oligomers) are modified with hydroxyl groups can be used. As such polyols, polybutadiene polyols (PBP), castor oil polyols, silicone-based polyols, fluorine-based polyols, polymer polyols (polyols in which acrylonitrile, styrene, etc. are copolymerized in polyether polyols and polymer fine particles are dispersed), polyrotaxanes having hydroxyl groups, etc. can be mentioned.

[0136] The number-average molecular weight of the prepolymer polyols is preferably 100 to 4000, more preferably 200 to 2000, and further preferably 500 to 1000.

[0137] It should be noted that the above number-average molecular weight is a polystyrene conversion value measured by GPC (gel permeation chromatography).

[0138] (urethane prepolymer)

[0139] A urethane prepolymer is a high-molecular compound obtained by reacting a polyol with an excessive amount of polyisocyanate, and its molecular terminal group has an isocyanate group. As the polyol and polyisocyanate constituting the urethane prepolymer, they can be appropriately selected from the above-mentioned polyols and polyisocyanates.

[0140] The synthesis method of the polyurethane resin is not particularly limited, and known methods can be used. In addition, commercially available products with a desired structure can also be used.

[0141] The content of MDI in the polyurethane resin only needs to be 30% by mass or more based on the total mass of the polyurethane resin, preferably 35% by mass or more, and more preferably 40% by mass or more. The upper limit of the content of MDI in the polyurethane resin is not particularly limited, and is usually 60% by mass or less, preferably 55% by mass or less.

[0142] The partial structure in the polyurethane and the content of MDI can be determined by NMR, IR, and mass analysis.

[0143] <Other Components>

[0144] The polishing layer can further contain other components within the scope of achieving the effects of the present invention. Examples of other components include blowing aids, carbon black, fine particles such as hollow particles, resins other than polyurethane resin, surfactants, etc.

[0145] Blowing aids, and fine particles such as carbon black and hollow particles can be used, for example, for the purposes of foaming the polyurethane resin and stabilizing the foaming shape, etc. Hollow particles are particles having a shell and a void inside. Examples of the material of the shell include polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, poly(meth)acrylamide, polyethylene glycol, polyhydroxy ether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, poly(meth)acrylonitrile, polyvinylidene chloride, polyvinyl chloride, and silicone-based resins.

[0146] The shape of the fine particles is not particularly limited, and examples include spherical, substantially spherical, etc. In addition, the average particle size of the fine particles is, for example, 5 μm to 200 μm, preferably 5 μm to 80 μm, and more preferably 10 μm to 50 μm.

[0147] When using fine particles, the content thereof is preferably 1% by mass to 25% by mass, more preferably 2% by mass to 20% by mass based on the total mass of the polishing layer.

[0148] The proportion of MDI in the polishing layer only needs to be 30% by mass or more based on the total mass of the polishing layer. From the aspect of polishing speed, among them, it is preferably 35% by mass or more, and more preferably 40% by mass or more. On the other hand, the upper limit of the content of MDI in the polishing layer is not particularly limited, and is usually 60% by mass or less, preferably 55% by mass or less.

[0149] <Physical Properties of the Polishing Layer, etc.>

[0150] In the polishing method of the present disclosure, the polishing layer is preferably suede-like. In the polishing method of the present disclosure, since the MDI in the polishing layer is 30% by mass or more, by combining a relatively soft suede-like polishing layer with abrasive grains, it is possible to balance the improvement of the polishing speed of the polished surface, particularly including the insulating film, and the suppression of polishing scratches.

[0151] For example, there is a concern that a hard polishing layer with a Shore A hardness exceeding 90 degrees may generate polishing scratches when increasing the polishing pressure during polishing.

[0152] From the viewpoint of suppressing excessive deformation and improving the planarization performance, the lower limit value of the Shore A hardness of the polishing layer is preferably 30 degrees, more preferably 40 degrees, further preferably 50 degrees, particularly preferably 60 degrees, and extremely preferably 65 degrees. On the other hand, from the viewpoint of suppressing polishing scratches by having moderate elasticity, the upper limit value of the Shore A hardness is preferably 90 degrees, more preferably 85 degrees, further preferably 80 degrees, and particularly preferably 75 degrees. It should be noted that the Shore A hardness is a value obtained by measuring the polishing layer peeled from the polishing pad according to JIS K7311.

[0153] The lower limit value of the water absorption rate of the polishing layer is preferably 5%, more preferably 10%, further preferably 15%, particularly preferably 20%, extremely preferably 25%, and most preferably 30%. On the other hand, the upper limit value of the water absorption rate of the polishing layer is preferably 80%, more preferably 70%, further preferably 65%, and extremely preferably 60%. By keeping the polishing agent moderately in the polishing layer within the range of 5% to 80% of the water absorption rate of the polishing layer, the number of contacts between the polishing agent and the polished surface increases, so the polishing efficiency per unit weight of the polishing agent is improved.

[0154] The water absorption rate of the polishing layer is a value obtained as follows. A test piece of the polishing layer to be tested is made into a 5 cm × 5 cm test piece. In the case where the polishing layer is a polishing pad with a substrate, the polishing layer is peeled from the substrate and used. The weight (W d [g]) of the above test piece is measured in a sufficiently dry state. Next, the test piece is immersed in deionized water (DIW) heated to 50 °C for 16 hours.

[0155] The test piece is taken out from the DIW, and all the water droplets on the surface are wiped off with a dry BEMCOT, and the weight (W w [g]) is measured within 1 minute. The water absorption rate is calculated based on each measured value and the following formula (1).

[0156] Water absorption rate [%] = (W w [g] - W d [g]) / W d [g] × 100 ··· (1)

[0157] Next, the preferred shape of the polishing layer will be described. Figure 3 is a schematic cross-sectional view of the polishing layer 30, Figure 4 which shows Figure 3 the surface of the polyurethane resin 40. Figure 3 is an enlarged view at a magnification of approximately 250 times, Figure 4 and is an enlarged view at a magnification of approximately 2000 times.

[0158] Figure 3 The shown polishing layer 30 is a porous layer having a plurality of pores 31 in the polyurethane resin 40. Further, when observing the surface of the polyurethane resin 40 in the polishing layer, it is preferred that the polyurethane resin 40 has a three-dimensional network structure as shown in Figure 4 . In the polyurethane resin (portion) 40 shown in Figure 4 , the three-dimensional network structure includes a network-shaped polyurethane resin 41 and fine pores 42 existing as the gaps of the network. By using a polishing layer having such a structure, the water absorption rate becomes appropriate, and it has excellent polishing speed, and at the same time, the generation of polishing scratches can be suppressed.

[0159] It should be noted that the pores 31 are pores observed at a size of about 1 to 10% of the field of view when observed with a scanning electron microscope (SEM) at a magnification of 250 times and a field of view of 600 μm square. In addition, the fine pores 42 are fine pores observed at a size of about 0.1 to 5% of the field of view when observed with a scanning electron microscope (SEM) at a magnification of 2000 times and a field of view of 100 μm square.

[0160] The lower limit value of the average pore diameter (diameter) of the pores 31 is preferably 20 μm, more preferably 25 μm, further preferably 30 μm, further more preferably 35 μm, particularly preferably 40 μm, extremely preferably 45 μm, and most preferably 50 μm. On the other hand, the upper limit value is preferably 150 μm, more preferably 130 μm, further preferably 110 μm, particularly preferably 90 μm, and extremely preferably 70 μm. It should be noted that the pore diameter of the pores 31 represents the major axis (d1) of the pores observed with a scanning electron microscope (SEM) at a magnification of 250 times, and the average pore diameter is the average value of the pore diameters of 30 or more pores 31 observed in the field of view.

[0161] The average pore diameter (diameter) of the fine pores 42 is at least smaller than the average pore diameter of the pores 31, and its lower limit value is preferably 0.1 μm, more preferably 0.5 μm, further preferably 1 μm, further more preferably 1.5 μm, and particularly preferably 2.5 μm. The pore diameter of the fine pores 42 represents the major axis of the fine pores observed with a scanning electron microscope (SEM) at a magnification of 2000 times, and the average pore diameter is the average value of the pore diameters of 30 or more fine pores 42 observed in the field of view.

[0162] In addition, the average thickness of the reticular polyurethane resin 41 is preferably from 0.1 μm to 5.0 μm, more preferably from 0.2 to 3.0 μm, and still more preferably from 0.3 to 1.8 μm. The thickness of the polyurethane resin 41 is the width of the polyurethane resin 41 observed by a scanning electron microscope (SEM) at a magnification of 2000 times, and can be obtained from the distance between two fine pores 42. The average thickness of the polyurethane resin 41 is the average value of the thicknesses of 30 or more polyurethane resins 41 observed in the visual field.

[0163] Furthermore, the lower limit of the ratio (D1 / μm] / D2[μm]) of the average pore diameter (D1[μm]) of the above-mentioned pores 31 to the average pore diameter (D2[μm]) of the above-mentioned fine pores 42 is 5.0, preferably 6.5, more preferably 8.0. On the other hand, the upper limit of D1 / D2 is 200, preferably 150, more preferably 100, still more preferably 50, still more preferably 40, particularly preferably 30, and most preferably 20. By setting the value of D1 / D2 within the above range, the water absorption rate becomes appropriate, and excellent polishing speed is achieved, while the generation of polishing scratches can be suppressed.

[0164] It should be noted that in the case of a hard polishing layer, it is presumed that the fine pores 42 are so small that they cannot be observed at a magnification of 2000 times by a scanning electron microscope (SEM), and D2 is an extremely small value. Therefore, D1 / D2 takes at least a value greater than 100.

[0165] The thickness of the polishing layer is not particularly limited, and for example, it can be about 0.3 mm to 2.0 mm, preferably 0.5 mm to 1.5 mm.

[0166] <Method for manufacturing the polishing layer (polishing pad)>

[0167] From the viewpoint of forming the above-mentioned suede-like polishing layer, the polishing layer is preferably formed by a wet film-forming method. Specific examples are given below for explanation.

[0168] First, a solution containing a polyurethane resin is prepared. This solution contains a polyurethane resin, a solvent, and other components used as required. As the solvent, a solvent that can dissolve the polyurethane resin and has water miscibility can be used. Specific examples of such a solvent include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetone, etc.

[0169] Next, the above solution is coated on a substrate for film formation to form a coating film. The coating method of the solution can be appropriately selected from known methods capable of uniform coating. In addition, the substrate for film formation is not particularly limited, and a flexible film such as a polyethylene terephthalate film, a polyester film, or a polyolefin film can be used, or a peelable substrate can also be used.

[0170] Next, the substrate coated with the above solution is immersed in a coagulating liquid mainly composed of water. As the coagulating liquid, water, a mixed solution of water and a polar solvent such as DMF, etc. can be used. As the polar solvent, a water-miscible organic solvent for dissolving the polyurethane resin can be used. The concentration of the polar solvent in the mixed solvent is preferably 0.5% by mass to 30% by mass. The temperature of the coagulating liquid and the immersion time are not particularly limited. For example, it is sufficient to immerse at 5 to 80 °C for 5 to 60 minutes. Thereby, an abrasive layer containing a polyurethane resin is formed.

[0171] The obtained abrasive layer is subjected to cleaning and drying treatments with or without being peeled from the substrate.

[0172] The organic solvent remaining in the polyurethane resin is removed by the cleaning treatment. As the cleaning liquid used in the cleaning, water can be cited.

[0173] After cleaning, the polyurethane resin is subjected to a drying treatment. The drying treatment can be carried out by a conventional method. For example, it is sufficient to dry at 80 to 150 °C in a dryer for about 5 to 60 minutes. Through the above steps, a suede-type soft abrasive layer with a specified structure can be obtained.

[0174] Other layers such as a substrate can be further laminated on the obtained abrasive layer. The substrate preferably has a Shore A hardness higher than that of the abrasive layer.

[0175] Furthermore, the surface of the abrasive layer can be subjected to grinding treatment, grooving, or pattern processing as needed.

[0176] [Surface to be polished]

[0177] In this polishing method, the surface to be polished includes an insulating film. As the material of the insulating film, silicon oxide, silicon nitride, polysilicon, etc. can be cited, and two or more insulating films can be arranged on one surface to be polished. According to this polishing method, when the surface to be polished includes silicon oxide among the above insulating films, the polishing rate and the selectivity are particularly excellent.

[0178] Examples of the surface to be polished include the surface of a semiconductor substrate that includes a surface made of silicon dioxide, a blanket wafer in which a silicon nitride film and a silicon dioxide film are stacked on the surface of the semiconductor substrate, and a patterned wafer in which these film types are arranged in a pattern. As the semiconductor substrate, a substrate for STI is cited as a preferred example. The abrasive of the present invention is also effective for polishing used for planarization of an interlayer insulating film between multiple wirings in the manufacture of a semiconductor device. It should be noted that although this polishing method features an increased polishing rate of the insulating film, it can also be applied to polishing of a surface to be polished that does not have an insulating film.

[0179] As the silicon dioxide film in the substrate for STI, a so-called PE-TEOS film formed using tetraethoxysilane (TEOS) as a raw material and by plasma CVD can be cited. Additionally, as the silicon dioxide film, a so-called HDP film formed by high-density plasma CVD can be cited. Further, HARP films and FCVD films formed by other CVD methods, and SOD films formed by spin coating can also be used. As the silicon nitride film, a silicon nitride film formed using silane or dichlorosilane and ammonia as raw materials and by low-pressure CVD or plasma CVD, and a silicon nitride film formed by ALD can be cited.

[0180] [Polishing Method]

[0181] In the polishing method of the present embodiment, while supplying the above-mentioned abrasive, the surface to be polished is brought into contact with the polishing layer of the above-mentioned polishing pad, and polishing is performed by the relative movement of the two.

[0182] This polishing method can use a known polishing apparatus. Figure 2 It is a schematic diagram showing an example of a polishing apparatus. Figure 2 The polishing apparatus 20 shown in the example of includes: a polishing head 22 that holds a semiconductor substrate 21 having a surface to be polished that includes resin; a polishing table 23; a polishing pad 24 attached to the surface of the polishing table 23; and an abrasive supply pipe 26 that supplies an abrasive 25 to the polishing pad 24. It is configured such that while supplying the abrasive 25 from the abrasive supply pipe 26, the surface to be polished of the semiconductor substrate 21 held by the polishing head 22 is brought into contact with the polishing pad 24, and polishing is performed by the relative rotational movement of the polishing head 22 and the polishing table 23.

[0183] The polishing head 22 can not only perform rotational motion but also perform linear motion. In addition, the polishing table 23 and the polishing pad 24 can be sized to be the same as or smaller than the semiconductor substrate 21. In this case, it is preferable to relatively move the polishing head 22 and the polishing table 23 so that the entire polished surface of the semiconductor substrate 21 can be polished. Further, the polishing table 23 and the polishing pad 24 may not perform rotational motion and may move in one direction in a belt-like manner, for example.

[0184] The polishing conditions of such a polishing apparatus 20 are not particularly limited. By applying a load to the polishing head 22 and pressing it against the polishing pad 24, the polishing pressure is further increased and the polishing speed is increased. The polishing pressure is preferably about 0.5 to 50 kPa, and more preferably about 3 to 40 kPa from the viewpoints of the uniformity, flatness, and prevention of polishing defects such as scratching in the polished surface of the semiconductor substrate 21 under the polishing speed. The rotation speeds of the polishing table 23 and the polishing head 22 are preferably about 50 to 500 rpm. In addition, the supply amount of the polishing agent 25 can be appropriately adjusted according to the composition of the polishing agent, the above various polishing conditions, and the like.

[0185] If necessary, the pad conditioner can be brought into contact with the surface of the polishing pad 24, and polishing can be performed while adjusting the surface of the polishing pad 24.

[0186] According to this polishing method, the polished surface including the insulating film can be polished at high speed.

[0187] · Method for manufacturing semiconductor components

[0188] The method for manufacturing a semiconductor component of the present invention obtains a semiconductor component by singulating a semiconductor substrate, and the semiconductor substrate has a polished surface polished by the above-described polishing method of the present invention.

[0189] The method for manufacturing a semiconductor component disclosed in the present disclosure has at least a step of singulating a semiconductor substrate having a polished surface polished by the above polishing method. For the singulation step, for example, there is a step of cutting the above semiconductor substrate (for example, a semiconductor wafer) by a known method such as blade cutting, laser cutting, or plasma cutting to obtain a semiconductor wafer, that is, a semiconductor component.

[0190] The method for manufacturing this semiconductor component may further have a bonding step of bonding other components to the polished surface of the above semiconductor wafer. Through this step, a semiconductor component as a bonded body can be obtained.

[0191] As other components, a second semiconductor wafer, a rewiring layer, etc. may be cited. It should be noted that the second semiconductor wafer may be a semiconductor wafer obtained by the manufacturing method of the present disclosure, or a semiconductor wafer obtained by other methods. As the above bonding process, for example, it may be a process of directly disposing other components on the ground surface and directly bonding them by fusion bonding, surface activated bonding, etc., or a process of bonding the ground surface and other components via an adhesive layer. As the adhesive layer, metal layers such as solder and copper, glass layers, resin layers such as polyimide and epoxy, etc. may be cited.

[0192] The present disclosure further provides an electronic device including at least one semiconductor component having a ground surface polished by the polishing method of the present disclosure.

[0193] Examples

[0194] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited to these examples. It should be noted that Examples 1 to 3 and Example 7 are examples, and Examples 4 to 6 and Examples 8 to 9 are comparative examples.

[0195] <Measurement method>

[0196] [pH]

[0197] The pH was measured using a pH meter HM-30R manufactured by Toa DKK Corporation, and the temperature was set to 25 ± 5°C.

[0198] [Average secondary particle size]

[0199] The average secondary particle size was measured using a laser scattering / diffraction type particle size distribution measuring device (manufactured by Horiba, Ltd., device name: LA-950).

[0200] [Shape of the polishing layer]

[0201] The pore diameters of the holes and micropores, and the coarseness of the reticulated polyurethane resin were measured by observing the cross-section of the polishing layer with a scanning electron microscope (SEM) at a magnification of 250 times or 2000 times. The pore diameters and coarseness were set as the average values of 30 or more values observed in the field of view.

[0202] [Water absorption rate of the polishing layer]

[0203] For each of the polishing pads described later, after peeling the substrate to form a single film of the polishing layer, a test piece of 5 cm × 5 cm was made. Each test piece was weighed (W) in a sufficiently dried state. d[g]). Next, each test piece was immersed in deionized water (DIW) heated to 50 °C for 16 hours. Then, the test piece was taken out of the DIW, and all water droplets on the surface were wiped off with a dry BEMCOT. The weight (W w [g]) was measured within 1 minute, and the water absorption rate was calculated according to the above formula (1).

[0204] [Composition of polishing pad]

[0205] <Microscopic FT-IR>

[0206] A part of the polishing layer was taken, rolled and thinned using a micro roller, and the film was bonded to a crystal plate (BaF2) to prepare a sample, and microscopic FT-IR measurement was performed.

[0207] Measuring device: Manufactured by JASCO Corporation, Microscopic FT-IR, FT-IR-4100, IRT-3000 Scanning range: 4000 cm －1 ~650 cm －1

[0208] <NMR>

[0209] A part of the polishing layer was taken, dissolved in DMF-D7, and NMR measurement was performed.

[0210] Measuring device: Manufactured by JEOL Ltd., JNM-ECX400

[0211] Magnet: 400 MHz

[0212] Observed nucleus: 13 C

[0213] Deuterated solvent: DMF-D7

[0214] Sample concentration: Approximately 5 w / v%

[0215] Measuring temperature: 80 °C

[0216] <CHN elemental analysis>

[0217] A part of the polishing layer was taken and CHN elemental analysis was performed.

[0218] Device: MICRO CORDER JM10 manufactured by J-SCIENCE CO., LTD.

[0219] Sample furnace: 950 °C

[0220] Combustion furnace: 850 °C

[0221] Reduction furnace: 550 °C

[0222] [Abrasive]

[0223] Prepare an abrasive by mixing the components in such a way as to form the following composition. It should be noted that in any of the abrasives, the content of cerium oxide is 95% by mass or more relative to the total mass of the abrasive grains.

[0224] <Abrasive A>

[0225] · Cerium oxide particles with an average secondary particle size of 110 nm: 0.25% by mass

[0226] · Polyacrylic acid: 0.053% by mass

[0227] · Nitric acid: 0.024% by mass

[0228] · Water: the remainder

[0229] <Abrasive B>

[0230] · Cerium oxide particles with an average secondary particle size of 110 nm: 0.25% by mass

[0231] · Water: the remainder

[0232] [Polishing pad]

[0233] Use a polishing pad with the following characteristics.

[0234] <Polishing pad A>

[0235] · Thickness: 0.9 mm

[0236] · Polishing layer: suede type, with polyurethane resin as the main component.

[0237] · Polyurethane resin: contains structural units from MDI and structural units from polyester polyol, and the polyester polyol contains structural units from adipic acid.

[0238] · MDI content: 36% by mass (based on the total mass of the polishing layer)

[0239] <Polishing pad B>

[0240] · Thickness: 1.48 mm

[0241] · Polishing layer: suede type, with polyurethane resin as the main component.

[0242] · Polyurethane resin: contains structural units from MDI and structural units from polytetramethylene glycol.

[0243] · MDI content: 51% by mass (based on the total mass of the polishing layer)

[0244] <Polishing pad C>

[0245] · Thickness: 1.23 mm

[0246] · Polishing layer: suede type, with polyurethane resin as the main component.

[0247] · Polyurethane resin: contains structural units from MDI and structural units from polyester polyol, and the polyester polyol contains structural units from adipic acid.

[0248] · MDI content: 27% by mass (based on the total mass of the polishing layer)

[0249] <Polishing pad D>

[0250] · Manufactured by DuPont, product number: IC1400

[0251] · Thickness: 2.73 mm

[0252] · Polishing layer: hard type, with polyurethane resin as the main component.

[0253] · Polyurethane resin: contains structural units from TDI, structural units from polyether polyol, and structural units from 4,4'-methylenebis(2-chloroaniline) (MOCA).

[0254] · MDI content: 0% by mass (based on the total mass of the polishing layer)

[0255] <Polishing pad E>

[0256] · Manufactured by DuPont, product number: IK4250H

[0257] · Thickness: 2.84 mm

[0258] · Polishing layer: hard type, with polyurethane resin as the main component.

[0259] · Polyurethane resin: contains structural units from TDI, structural units from polyether polyol, and structural units from 4,4'-methylenebis(2-chloroaniline) (MOCA).

[0260] · MDI content: 0% by mass (based on the total mass of the polishing layer)

[0261] [Polishing speed evaluation]

[0262] (Examples 1 - 6)

[0263] Prepare the following items as the objects to be polished (workpieces to be polished).

[0264] · A blank substrate with a silica film formed by plasma CVD method on an 8-inch silicon wafer using tetraethoxysilane as the raw material

[0265] ·A blank substrate with a silicon nitride film formed on an 8-inch silicon wafer by CVD method

[0266] ·A blank substrate with a polysilicon film formed on an 8-inch silicon wafer by CVD method

[0267] Next, as shown in Table 1, the abrasive and the polishing pad are combined, and the above object to be polished is polished using a fully automatic CMP polishing apparatus (manufactured by Applied Materials, apparatus name: Mirra). In the adjustment of the polishing pad, the diamond pad conditioner (manufactured by 3M, product name: A82) is used in Examples 1 to 4, and the diamond pad conditioner (manufactured by 3M, product name: A165) is used in Examples 5 to 6.

[0268] Regarding the polishing conditions, the polishing pressure is set to 20.7 kPa, the rotation speed of the polishing table is set to 127 rpm, and the rotation speed of the polishing head is set to 123 rpm. In addition, the supply speed of the abrasive is 200 ml / min.

[0269] The polishing rate is calculated using the film thickness meter UV-1280SE of KLA-Tencor Corporation based on the change in the film thickness and the polishing time of the object to be polished. In addition, the selectivity (the ratio of the polishing rates) is calculated based on each polishing rate. The results are shown in Table 1

[0270] [Table 1]

[0271]

[0272] It should be noted that "unmeasurable" in Table 1 means that it is so fine that it cannot be observed in an SEM image at a magnification of 2000 times.

[0273] In the polishing methods of Examples 1 to 3 using a polishing pad with a polishing layer having 30 mass% or more of MDI, the polishing rate of any one of TEOS, SiN, and polysilicon is shown to be superior to that of Examples 4 to 6. Thus, the control of the selectivity becomes easy. For example, as shown by the comparison between Example 1 and Example 2, the selectivity can be controlled by adjusting the pH.

[0274] [Polishing scratch evaluation] (Examples 7 to 9)

[0275] As the object to be polished (the object to be polished), a blank substrate with a silica film formed on a 12-inch silicon wafer using tetraethoxysilane as a raw material by plasma CVD method is prepared.

[0276] Next, as shown in Table 2, the abrasive and the polishing pad were combined, and the object to be polished was polished using a fully automatic CMP polishing apparatus (manufactured by Ebara Corporation, apparatus name: F-Rex300X). In the adjustment of the polishing pad, in Example 7, a diamond pad conditioner (manufactured by 3M Company, product name: A82) was used, and in Examples 8 to 9, a diamond pad conditioner (manufactured by 3M Company, product name: A165) was used. For the polishing conditions, the polishing pressure was set to 20.7 kPa, the rotation speed of the polishing table was set to 100 rpm, and the rotation speed of the polishing head was set to 101 rpm. In addition, the supply rate of the abrasive was 250 ml / min.

[0277] The polishing scratches were obtained by the following operation: The polished object to be polished was cleaned, and then, using an optical wafer defect inspection apparatus (manufactured by KLA-Tencor Corporation, apparatus name: Surfscan SP5) and a wafer defect reinspection apparatus (manufactured by KLA-Tencor Corporation, apparatus name: eDR7280), the number of polishing scratches with a size of 0.05 μm or more on each polished object was counted.

[0278] As a result, there were 3 in Example 7, 40 in Example 8, and 63 in Example 9. That is, according to the polishing method of the present invention, as shown in Table 1, not only can the polishing speed and selectivity of the insulating film as high as those in the case of using a hard pad be maintained, but also the generation of polishing scratches can be significantly suppressed.

[0279] [Table 2]

[0280]

[0281] Industrial Applicability

[0282] According to the present invention, for example, high-speed polishing can be achieved in CMP of a polished surface including an insulating film. Therefore, the polishing method of the present invention is suitable for polishing an insulating film for STI in the manufacture of semiconductor devices.

[0283] This application claims priority based on Japanese Patent Application No. 2022-168156 filed on October 20, 2022, and Japanese Patent Application No. 2023-036300 filed on March 9, 2023, and incorporates the entire contents disclosed therein into this specification.

[0284] Symbol Explanation

[0285] 1... Silicon substrate, 2... Silicon nitride film, 3... Groove, 4... Silicon oxide film, 20... Polishing device, 21... Semiconductor substrate, 22... Polishing head, 23... Polishing platform, 24... Polishing pad, 25... Polishing agent, 26... Polishing agent supply pipe, 30... Polishing layer, 31... Hole, 40... Polyurethane resin, 41... Mesh-like polyurethane resin, 42... Microscopic hole, d1... Diameter of the hole, d2... Diameter of the microscopic hole, W... Thickness of the mesh-like polyurethane resin.

Claims

1. A polishing method in which while supplying a polishing agent, a polished surface of a semiconductor substrate is brought into contact with a polishing pad, and polishing is performed by relative movement between the two. The polishing agent contains abrasive grains and water. The polishing pad has a polishing layer containing a polyurethane resin. The Shore A hardness of the polishing layer is 90 degrees or less. The water absorption rate of the polishing layer is 5% or more. The polyurethane resin contains structural units derived from methylene diphenyl diisocyanate (MDI). The content of the methylene diphenyl diisocyanate is 30% by mass or more relative to the total mass of the polishing layer. The polished surface contains an insulating film.

2. The grinding method according to claim 1, wherein, The abrasive grains contain at least one selected from silica particles, alumina particles, zirconia particles, cerium compound particles, titanium dioxide particles, germanium oxide particles, and core-shell type particles having these particles as core particles.

3. The grinding method according to claim 1, wherein, The abrasive grains contain cerium oxide particles.

4. The grinding method according to claim 1, wherein, The content of the abrasive grains is 0.01% by mass to 10.0% by mass relative to the total mass of the polishing agent.

5. The grinding method according to claim 1, wherein, The polishing agent further contains a dispersant.

6. The grinding method according to claim 5, wherein, The dispersant contains at least one selected from an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

7. The grinding method according to claim 5, wherein, The content of the dispersant is 0.0001% by mass to 0.3% by mass relative to the total mass of the polishing agent.

8. The grinding method according to claim 1, wherein, The polishing layer is of the suede type.

9. The lapping method according to claim 1, wherein, The polishing layer is formed by a wet film-forming method.

10. The grinding method according to claim 1, wherein, The polishing layer is a porous layer having a plurality of pores in the polyurethane resin portion. The polyurethane resin portion has a three-dimensional network structure including a network-like polyurethane resin and fine pores.

11. The grinding method according to claim 10, wherein, When the average pore diameter of the plurality of pores in the polyurethane resin portion is D1 and the average pore diameter of the fine pores is D2, D1 / D2 is 5.0 to 200.

12. The grinding method according to claim 1, wherein, The polyurethane resin contains structural units derived from a polyether polyol or a polyester polyol.

13. The grinding method according to claim 1, wherein, The insulating film contains at least one selected from silicon oxide, silicon nitride, and polysilicon.

14. A method for manufacturing a semiconductor component, in which a semiconductor component is obtained by singulating a semiconductor substrate having a polished surface polished by the polishing method according to any one of claims 1 to 13.

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