Polishing agent, polishing method, method for manufacturing semiconductor component, and additive solution for polishing agent

Abstract

Provided is a polishing agent which maintains the polishing speed of a silicon oxide film, achieves a high selectivity between the silicon oxide film and a barrier film, and has excellent storage stability. The polishing agent includes abrasive grains, an anionic polymer, an acidic compound selected from a phosphoric acid compound and an organic acid compound, and water, the anionic polymer being a copolymer including a hydrophobic monomer and an anionic monomer, the anionic polymer having an acid value of 20-400 mgKOH / g, the hydrophobic monomer having a partition coefficient of 0-4, and the anionic monomer having a partition coefficient of 0-4. The anionic monomer contains at least one selected from the group consisting of unsaturated monocarboxylic acids and salts thereof, and when the acidic compound having the highest molar concentration among the acidic compounds is defined as a first acidic compound, the pKa of the first acidic compound and the pH of the polishing agent satisfy the relationship represented by formula (1). | pKa-pH | < = 1.5 (1)

Description

Technical Field

[0001] This disclosure relates to abrasives, abrasive methods, methods for manufacturing semiconductor components, and additives for abrasives. Background Technology

[0002] With the increasing integration and functionality of semiconductor integrated circuits, the development of microfabrication technologies for miniaturization and high density of semiconductor devices is constantly advancing. Historically, in the manufacturing of semiconductor integrated circuit devices (hereinafter also referred to as semiconductor equipment), chemical mechanical polishing (CMP) has been used to planarize interlayer insulating films, embedded wiring, and other components to prevent surface roughness (step differences) from exceeding the depth of focus in photolithography and thus achieving insufficient resolution. As the requirements for high precision and miniaturization of devices become more stringent, the importance of utilizing CMP for high planarization is becoming increasingly prominent.

[0003] In addition, in the manufacturing of semiconductor devices, in order to advance the miniaturization of semiconductor components, a separation method using shallow trenches with small separation widths (STI) has been introduced.

[0004] STI is a method of forming electrically insulating component regions by forming trenches (grooves) in a silicon substrate and embedding an insulating film within the trenches. (See reference...) Figure 1A , Figure 1B Let's illustrate this with an example of STI. In this example, firstly, as... Figure 1A As shown, after the device area of ​​the silicon substrate 1 is masked by the barrier film 2, a trench 3 is formed on the silicon substrate 1, and an insulating film such as a silicon oxide film 4 is deposited to fill the trench 3. Next, CMP is used to remove the silicon oxide film 4 from the trench 3 (which is a recess) while simultaneously grinding away the silicon oxide film 4 on the barrier film 2 (which is a protrusion). Figure 1B As shown, a component separation structure with a silicon oxide film 4 embedded in the trench 3 is obtained.

[0005] In CMP within STI, by increasing the selectivity ratio (grinding speed ratio) of the silicon oxide film to the barrier film, grinding can be stopped the moment the barrier film is exposed. Examples of such barrier films include nitride films and polycrystalline silicon. Compared to conventional grinding methods, grinding methods using barrier films can produce smoother surfaces. Furthermore, high selectivity ratios are increasingly required in recent CMP technologies.

[0006] For example, in Patent Document 1, as a method for improving the selectivity ratio of silicon dioxide film to silicon nitride film, an abrasive containing a specific water-soluble polymer, cerium oxide particles and water, and having a pH of 4 to 9 is disclosed.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2019-87660 Summary of the Invention

[0010] In view of the above-mentioned problems, the present disclosure aims to provide an abrasive that achieves a high selectivity ratio between the silicon oxide film and the barrier film while maintaining the polishing speed of the silicon oxide film, and also has excellent storage stability; an abrasive additive for preparing the abrasive; a polishing method capable of high-speed polishing; and a method for manufacturing a semiconductor device using the polishing method.

[0011] This disclosure provides an abrasive, an abrasive additive, an abrasive method, and a method for manufacturing a semiconductor component having the following components.

[0012] [1] An abrasive comprising abrasive particles, an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water.

[0013] The aforementioned anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers.

[0014] The acid values ​​of the above-mentioned anionic polymers range from 20 mg KOH / g to 400 mg KOH / g.

[0015] The partition coefficients (logD) of the aforementioned hydrophobic monomers range from 0 to 4.

[0016] The aforementioned anionic monomers include at least one selected from unsaturated monocarboxylic acids and their salts.

[0017] When the acidic compound with the highest molar concentration among the above acidic compounds is designated as the first acidic compound,

[0018] The pKa of the first acidic compound and the pH of the abrasive satisfy the relationship of equation (1).

[0019] |pKa-pH|≤1.5・・・(1)

[0020] When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

[0021] [2] According to the abrasive of [1], wherein the abrasive particles comprise at least one selected from silica particles, alumina particles, zirconium oxide particles, cerium compound particles, titanium dioxide particles, germanium oxide particles and their composite particles, and core-shell particles.

[0022] [3] According to the abrasive of [1] or [2], wherein the abrasive grains contain cerium compound particles.

[0023] [4] The abrasive according to any one of [1] to [3], wherein the abrasive particles comprise cerium oxide particles.

[0024] [5] The abrasive according to any one of [1] to [4], wherein the content of the abrasive particles is 0.01% to 10.0% by mass relative to the total mass of the abrasive.

[0025] [6] The abrasive according to any one of [1] to [5], wherein the acid value of the above anionic polymer is 20 mg KOH / g to 300 mg KOH / g.

[0026] [7] The abrasive according to any one of [1] to [6], wherein the partition coefficient (logD) of the above-mentioned hydrophobic monomer is 0 to 3.

[0027] [8] The abrasive according to any one of [1] to [7], wherein the hydrophobic monomer comprises an alkyl methacrylate.

[0028] [9] The abrasive according to any one of [1] to [8], wherein the weight average molecular weight of the above-mentioned anionic polymer is 1,000 to 100,000.

[0029]

[10] According to any one of [1] to [9], wherein the proportion of the hydrophobic monomer in the above-mentioned anionic polymer is 10 to 95 moles relative to all the monomers constituting the anionic polymer.

[0030]

[11] The abrasive according to any one of [1] to

[10] , wherein the content of the above-mentioned anionic polymer is 0.02% to 0.5% by mass relative to the total mass of the above-mentioned abrasive.

[0031]

[12] The abrasive according to any one of [1] to

[11] , wherein the above pKa is 4 to 9.

[0032]

[13] The abrasive according to any one of [1] to

[12] , wherein it further comprises a nonionic polymer.

[0033]

[14] The abrasive according to any one of [1] to

[13] , wherein the pH is 4 to 9.

[0034]

[15] A polishing method is a method in which polishing is performed by simultaneously supplying polishing agent to the surface of a semiconductor substrate and bringing it into contact with a polishing pad, thereby achieving polishing through the relative movement of the two surfaces.

[0035] The above-mentioned abrasive is any one of [1] to

[14] .

[0036]

[16] A method for manufacturing a semiconductor component, wherein a semiconductor component is obtained by monolithically processing a semiconductor substrate having a polished surface polished by the polishing method of

[15] .

[0037]

[17] An abrasive additive liquid comprises an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water.

[0038] The aforementioned anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers.

[0039] The acid values ​​of the above-mentioned anionic polymers range from 20 mg KOH / g to 400 mg KOH / g.

[0040] The partition coefficients (logD) of the aforementioned hydrophobic monomers range from 0 to 4.

[0041] The aforementioned anionic monomers include at least one selected from unsaturated monocarboxylic acids and their salts.

[0042] When the acidic compound with the highest molar concentration among the above acidic compounds is designated as the first acidic compound,

[0043] The pKa of the first acidic compound and the pH of the abrasive additive solution satisfy the relationship of equation (1).

[0044] |pKa-pH|≤1.5・・・(1)

[0045] When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

[0046] According to this disclosure, an abrasive that achieves a high selectivity ratio between the silicon oxide film and the barrier film while maintaining the grinding speed of the silicon oxide film, and also exhibits excellent storage stability, can be provided, along with an abrasive additive for preparing the abrasive, a grinding method capable of high-speed grinding, and a method for manufacturing a semiconductor component using the grinding method. Attached Figure Description

[0047] Figure 1A This is a diagram illustrating an example of a grinding method, and this is a cross-sectional view showing the state of the object to be ground before grinding.

[0048] Figure 1B This is a diagram illustrating an example of a grinding method, and this is a cross-sectional view showing the state of the object after grinding.

[0049] Figure 2 This is a schematic diagram illustrating an example of a grinding apparatus. Detailed Implementation

[0050] The embodiments of the present invention will now be described. The present invention is not limited to the following embodiments; other embodiments that conform to the spirit of the present invention may also fall within its scope. For clarity, the following description and drawings will be appropriately simplified. Furthermore, for illustrative purposes, the scales of the components in the drawings may sometimes differ significantly.

[0051] It should be noted that in this disclosure, "surface to be polished" refers to the surface of the object being polished, such as its surface. In this specification, the surface that appears at an intermediate stage in the process of manufacturing semiconductor devices is also included in "surface to be polished".

[0052] "Silicon oxide" mainly refers to silicon dioxide, but it is not limited to this and can also include silicon oxides other than silicon dioxide.

[0053] "Selection ratio" refers to the grinding speed (R) of the object being ground (e.g., silicon oxide film). A The polishing speed (R) of the barrier film B (e.g., silicon nitride film) and the polishing speed of the barrier film B (e.g., silicon nitride film) B The ratio of (R) A / R B ).

[0054] "(Meth)acrylic acid" is a general term for "methacrylic acid" and "acrylic acid", as are (meth)acryloyl, (meth)acrylate, etc.

[0055] In addition, unless otherwise specified, the "~" sign indicating a range of values ​​includes the values ​​before and after it as the lower and upper limits.

[0056] [Abrasive]

[0057] The abrasive disclosed herein (hereinafter also referred to as the abrasive) is an abrasive comprising abrasive particles, an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water.

[0058] The aforementioned anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers.

[0059] The acid values ​​of the above-mentioned anionic polymers range from 20 mg KOH / g to 400 mg KOH / g.

[0060] The partition coefficients (logD) of the aforementioned hydrophobic monomers range from 0 to 4.

[0061] The aforementioned anionic monomers include at least one selected from unsaturated monocarboxylic acids and their salts.

[0062] When the acidic compound with the highest molar concentration among the above acidic compounds is designated as the first acidic compound,

[0063] The pKa of the first acidic compound and the pH of the abrasive satisfy the relationship of equation (1).

[0064] |pKa-pH|≤1.5・・・(1)

[0065] When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

[0066] By using this abrasive in CMP (Continuous Polishing) of surfaces containing a silica film, such as those in STI (Stone Inkjet), a high abrasive speed can be maintained on the silica film while suppressing abrasion of the barrier film, resulting in a high selectivity ratio between the silica film and the barrier film, and achieving a high degree of flatness. Furthermore, this abrasive exhibits excellent storage stability, suppressing changes in pH and viscosity even during long-term storage.

[0067] It should be noted that, as a barrier film, examples include compounds containing one or more of silicon, carbon, hafnium, zirconium, cobalt, ruthenium, molybdenum, titanium, tantalum, and copper, or nitrides or oxides containing one or more of them. More specifically, examples include elemental metals such as copper, cobalt, ruthenium, molybdenum, titanium, and tantalum; nitrides such as titanium nitride, tantalum nitride, and silicon nitride; oxides such as zirconium oxide and hafnium oxide; polycrystalline silicon, amorphous silicon, hafnium silicate, zirconium silicate, and silicon carbide. From the perspective of obtaining a higher selectivity, silicon nitride or polycrystalline silicon is preferred.

[0068] This abrasive contains at least abrasive grains, anionic polymers, acidic compounds, and water, and may further contain other components to achieve the effects described in this embodiment. The components that may be included in this abrasive are described below.

[0069] <Abrasive>

[0070] In this abrasive, the abrasive grains can be appropriately selected from those used for CMP. Examples of abrasive grains include, for instance, at least one selected from silica particles, alumina particles, zirconium oxide particles, cerium compound particles (e.g., cerium oxide particles, cerium hydroxide particles), titanium dioxide particles, germanium oxide particles, and core-shell particles using these as core particles. Examples of silica particles include colloidal silica and fumed silica. Colloidal alumina can also be used as alumina particles.

[0071] The aforementioned core-shell particles consist of a core particle (such as silicon dioxide particles, aluminum oxide particles, zirconium oxide particles, cerium compound particles, titanium dioxide particles, and germanium oxide particles) and a thin film covering the surface of the core particle.

[0072] Examples of materials for the aforementioned thin film include at least one selected from oxides such as silicon dioxide, aluminum oxide, zirconium oxide, cerium oxide, titanium dioxide, germanium oxide, iron oxide, manganese oxide, zinc oxide, yttrium oxide, calcium oxide, magnesium oxide, lanthanum oxide, and strontium oxide. Furthermore, the aforementioned thin film can be formed using multiple nanoparticles composed of these oxides.

[0073] The particle size of the aforementioned nuclear particles is preferably 0.01 μm to 0.5 μm, more preferably 0.03 μm to 0.3 μm.

[0074] The particle size of the above-mentioned nanoparticles only needs to be smaller than the particle size of the above-mentioned nuclear particles, preferably 1nm to 100nm, more preferably 5nm to 80nm.

[0075] As abrasive grains, from the perspective of excellent grinding speed of the insulating film, silica particles, alumina particles, or cerium compound particles are preferred, with cerium compound particles being more preferred. When the surface being ground contains an insulating film (especially a silica film), from the perspective of obtaining a high grinding speed, cerium oxide particles are further preferred. In the case of core-shell type particles, the film preferably contains silica, alumina, or a cerium compound, with cerium oxide being more preferred. One type of abrasive grain can be used alone or in combination of two or more types.

[0076] The cerium oxide content relative to the total mass of the abrasive particles 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% by mass. If the cerium oxide content relative to the total mass of the abrasive particles is 70% by mass or more, it is particularly easy to increase the grinding speed of the insulating film.

[0077] Cerium oxide particles can be appropriately selected from known cerium oxide particles, such as those manufactured by methods described in Japanese Patent Application Publication Nos. 11-12561, 2001-35818, and 2010-505735. Specifically, examples include cerium oxide particles obtained by adding an alkali to an aqueous solution of cerium(IV) ammonium nitrate to prepare cerium hydroxide gel, followed by filtration, washing, and calcination; cerium oxide particles obtained by calcining high-purity cerium carbonate, followed by further pulverization and classification; and cerium oxide particles obtained by chemically oxidizing cerium(III) salts in a liquid.

[0078] Cerium oxide particles may contain impurities other than cerium oxide. The cerium oxide content in a single cerium oxide particle is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and most preferably 100% by mass (excluding impurities). If the cerium oxide content in the cerium oxide particles is 80% by mass or more, it is easy to increase the polishing speed of the insulating film.

[0079] 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 less than 0.5 μm, the mechanical action exerted on the surface being polished is reduced, thus suppressing the formation of polishing scratches such as abrasions on the polished surface. Furthermore, if the average particle size is 0.01 μm or more, abrasive grain aggregation is suppressed, resulting in excellent storage stability of the polishing compound and excellent polishing speed.

[0080] It should be noted that abrasive particles exist in liquids as aggregated particles (secondary particles) formed by the aggregation of primary particles; therefore, the average particle size mentioned above is the average secondary particle size. The average secondary particle size is measured using a dispersion in a dispersion medium such as pure water, and is determined by a laser diffraction-scattering particle size analyzer.

[0081] The lower limit of the abrasive content relative to the total mass of the abrasive is preferably 0.01% by mass, more preferably 0.05% by mass, even more preferably 0.1% by mass, and particularly preferably 0.15% by mass. If the abrasive content is above or above the aforementioned lower limit, an excellent grinding speed is achieved on the surface being ground. On the other hand, the upper limit of the abrasive content relative to the total mass of the abrasive is preferably 10.0% by mass, more preferably 8.0% by mass, even more preferably 5.0% by mass, particularly preferably 2.0% by mass, even more preferably 1.0% by mass, extremely preferably 0.8% by mass, and most preferably 0.5% by mass. If the abrasive content is below or below the aforementioned upper limit, abrasive aggregation can be suppressed, and the increase in viscosity of the abrasive is suppressed, resulting in excellent operability.

[0082] The zeta potential (surface potential) of the abrasive grains in the abrasive compound is preferably negative (less than 0 mV), more preferably -200 mV to -10 mV, even more preferably -150 mV to -20 mV, and particularly preferably -100 mV to -30 mV. If the zeta potential of the abrasive grains is within the above range, the dispersion stability of the abrasive grains and the flatness of the silicon oxide film after polishing can be improved.

[0083] The zeta potential of abrasive particles can be measured, for example, using a dynamic light scattering zeta potential measuring device (e.g., Beckman Coulter, Inc., trade name: DelsaNano C). The zeta potential of abrasive particles can be adjusted using anionic polymers, acidic compounds, additives, etc., as described later.

[0084] <Anionic polymers>

[0085] In this abrasive, the anionic polymer is a copolymer comprising a hydrophobic monomer with a partition coefficient (logD) of 0 to 4, and an anionic monomer selected from unsaturated monocarboxylic acids and their salts, with an acid value of 20 mg KOH / g to 400 mg KOH / g. By using this specific anionic polymer, the abrasion of the barrier film can be suppressed, resulting in a high selectivity ratio between the silica film and the barrier film. The composition of the anionic polymer is described below.

[0086] (Hydrophobic monomer)

[0087] In this disclosure, a hydrophobic monomer refers to a monomer whose solubility (hereinafter also referred to as "solubility") in 100g of water at 20°C is 10g or less. This anionic polymer uses a hydrophobic monomer with a partition coefficient (logD) of 0 to 4. By having structural units derived from this hydrophobic monomer in the aforementioned anionic polymer, the abrasion of the barrier film is further suppressed. Preferably, the partition coefficient of the hydrophobic monomer is 0 to 3.

[0088] In this disclosure, the partition coefficient (logD) of the hydrophobic monomer represents the molecular partition coefficient between the aqueous and lipophilic phases. Specifically, the hydrophobic monomer of the analyte, water (buffer solution), and organic solvent (n-octanol) are placed in a container, shaken thoroughly, and then phase separation is performed. The hydrophobic monomer in each phase is quantified, and the concentrations Co in the organic solvent and Cw in the water are calculated separately. The partition coefficient (logD) is then obtained by taking the common logarithm of the concentration ratio (Co / Cw). The partition coefficient (logD) in this disclosure uses a buffer solution as the aqueous phase at a pH of approximately 5.5. It should be noted that for monomers with known partition coefficients, reference values ​​can be used.

[0089] From the viewpoint of improving the selectivity, the lower limit of the logD of the hydrophobic monomer is 0, preferably 0.5, and more preferably 1.0. Furthermore, from the viewpoint of improving the polishing speed of the silicon oxide film, the upper limit of the logD of the hydrophobic monomer is 4, preferably 3.5, and more preferably 3.0.

[0090] The solubility of the hydrophobic monomer is preferably 7g or less, more preferably 5g or less, even more preferably 3g or less, and particularly preferably 2g or less.

[0091] Furthermore, the solubility parameter (SP value) of the hydrophobic monomer is preferably 10.5 or less, more preferably 10.2 or less, even more preferably 10.0 or less, even more preferably 9.8 or less, and particularly preferably 9.6 or less.

[0092] As a hydrophobic monomer, it is preferred to be a monomer that does not have ionic or hydrophilic groups, and more preferably a compound represented by the following formula (2).

[0093]

[0094] in,

[0095] R 1 It can be a hydrogen atom or a methyl group.

[0096] R 11 It is a hydrocarbon group that can have O or Si between carbon atoms, and hydrogen atoms can be replaced by halogen atoms.

[0097] L 1 It is a single bond or a divalent linker.

[0098] In the above formula (2), R 11 Substituents exhibiting hydrophobicity are hydrocarbon groups that can have O or Si between carbon-carbon atoms, and hydrogen atoms can be replaced by halogen atoms. As R 11 Examples of hydrocarbon groups in this context include alkyl, aryl, and aralkyl groups.

[0099] The alkyl group can be linear, branched, or cyclic. Furthermore, the number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 12. Specific examples of this alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, camphoryl, adamantyl, etc.

[0100] Examples of aryl groups include phenyl, biphenyl, naphthyl, tolyl, and xylyl. The number of carbon atoms in the aryl group is preferably 6 to 24, and more preferably 6 to 12.

[0101] In addition, aralkyl groups include benzyl, phenethyl, naphthylmethyl, and biphenylmethyl. The number of carbon atoms in an aralkyl group is preferably 7 to 20, and more preferably 7 to 14.

[0102] When R 11 When an aromatic ring is present, the hydrogen atoms of the aromatic ring may have substituents such as straight-chain or branched alkyl groups having 1 to 4 carbon atoms.

[0103] R 11 The hydrocarbon group can also have O or Si between carbon-carbon atoms, and hydrogen atoms can be replaced by halogen atoms.

[0104] Examples of hydrocarbon groups with O or Si between carbon atoms include -(CH2CH2O). x -、-(CH2O) x - Epoxides, -CH2Si(R) 12 )2-CH2- etc. Here, x represents the number of repeating units, preferably an integer from 1 to 18. Additionally, 2 R 12Each can be a hydrogen atom or a methyl group, independently.

[0105] Additionally, R 11 This can be achieved by replacing the hydrogen atoms in the hydrocarbon group of the above structure with halogen atoms. Examples of halogen atoms include F, Cl, Br, and I.

[0106] Based on hydrophobicity and ease of acquisition, R 11 Preferably, the hydrocarbon group does not contain O, Si, or halogen atoms.

[0107] L 1 To connect unsaturated double bonds with R 11 Single or divalent linker groups. As L 1 Examples include alkylene groups with 1 to 8 carbon atoms, and -(CH2CH2O). x -、-(CH2O) x -, -CONH-, -COO-, -C(=O)-, etc. Examples of alkylene groups with 1 to 8 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, and hexylene.

[0108] Based on ease of acquisition, L 1 Preferably, it is a single bond, -CONH-, or COO-.

[0109] Hydrophobic monomers can be used alone or in combination of two or more. From the perspective of dispersibility in abrasives, hydrophobic monomers can be combined with monomers that have cyclic structures and monomers that do not.

[0110] Specific examples of hydrophobic monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-dodecyl methacrylate, stearyl methacrylate, and other alkyl methacrylates; and cyclic methacrylates such as 1-methylcyclopentyl acrylate, cyclohexyl methacrylate, and benzyl methacrylate.

[0111] Vinyl monomers such as styrene, methylstyrene, vinyltoluene, p-tert-butylstyrene, chloromethylstyrene, vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride, preferably containing alkyl (meth)acrylates, more preferably alkyl (meth)acrylates having alkyl groups having 1 to 6 carbon atoms.

[0112] (Anionic monomer)

[0113] In this disclosure, the anionic monomer comprises at least one selected from unsaturated monocarboxylic acids and their salts (hereinafter also referred to as unsaturated carboxylic acids, etc.). Because the aforementioned anionic polymer has structural units derived from unsaturated monocarboxylic acids, the carboxyl groups are adsorbed onto the barrier membrane, and the anionic polymer functions as a protective membrane for the barrier membrane.

[0114] As an anionic monomer, it is preferred to be a monomer that does not have ionic groups or hydrophilic groups, and more preferably a compound represented by the following formula (3).

[0115]

[0116] in,

[0117] R 2 R 3 and R 4 Each can be independently a hydrogen atom or a hydrocarbon group.

[0118] R 5 It is a group having a carboxyl group or a salt thereof.

[0119] As R 2 ~R 4 Examples of hydrocarbon groups in R include alkyl, aryl, and aralkyl groups. Specific examples of alkyl, aryl, and aralkyl groups can be found in the R group mentioned above. 11 A similar example. In this abrasive, considering the interaction between the carboxyl groups and the barrier film, R... 2 ~R 4 The hydrocarbon group is preferably an alkyl group with 1 to 18 carbon atoms, more preferably an alkyl group with 1 to 6 carbon atoms, wherein methyl or ethyl is preferred, more preferably methyl.

[0120] R 5 The groups containing carboxyl groups or their salts preferably have -L 2 -R 21 The structure.

[0121] The above L 2 To connect unsaturated double bonds with R 21 Single or divalent linker groups. As L 2 Examples include alkylene groups with 1 to 8 carbon atoms, phenylene groups, and -(CH2CH2O). x -R 22 -、-(CH2O) x -R 22 -, -CONH-R 22 -、-COO-R 22 - etc. Where x is an integer from 1 to 18, R 22 Preferably, it is a single bond or an alkylene group having 1 to 8 carbon atoms.

[0122] As L 2 and R 22 Alkyl groups, such as methylene, ethylene, propylene, butylene, pentylene, and hexylene, can have halogen atoms as substituents.

[0123] From the perspective of ease of obtaining monomers, L 2 Single bonds, alkylene groups, or phenylene groups are preferred.

[0124] R 21 It is a carboxyl group or its salt.

[0125] When the carboxyl group is a salt, examples of counter cations include alkali metal ions, alkaline earth metal ions, and ammonium ions.

[0126] As R in equation (3) 2 ~R 5 The preferred combination can be exemplified by (I)R 2 For hydrogen or methyl, R 3 ~R 4 For hydrogen atoms, R 5 Combinations of carboxyl groups, etc. (acrylic acid, methacrylic acid); (II) R 2 and R 3 For hydrogen atoms, R 4 It is hydrogen or alkyl, R 5 -L 2 -R 21 L 2 (III) R is a combination of alkylene groups (unsaturated fatty acids); 2 ~R 4 For hydrogen atoms, R 5 -L 2 -R 21 L 2 Combinations of phenylene (vinylbenzoic acid), etc.

[0127] Specific examples of anionic monomers represented by formula (3) include (meth)acrylic acid, vinylbenzoic acid, 2-carboxyethyl (meth)acrylic acid, and unsaturated fatty acids. Anionic monomers may be used alone or in combination of two or more.

[0128] Furthermore, within the scope of the effects of this embodiment, the anionic monomer may include other anionic monomers besides unsaturated monocarboxylic acids. Examples of such other anionic monomers include allyl sulfonic acid, methyl allyl sulfonic acid, 2-(meth)acryloyloxyethyl phosphate, maleic acid (maleic anhydride), fumaric acid, itaconic acid, citraconic acid, and mesoconic acid.

[0129] The proportion of the other anionic monomers relative to the total anionic monomers is preferably 5 mol% or less, more preferably 2 mol% or less, even more preferably 1 mol% or less, and particularly preferably substantially non-existent.

[0130] (Other monomers)

[0131] In addition, within the scope of the effects of this embodiment, the anionic polymer may contain monomers other than hydrophobic monomers and anionic monomers.

[0132] Other monomers include (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dibutyl (meth)acrylamide, N-tert-butylacrylamide, N-phenyl (meth)acrylamide, N-benzyl (meth)acrylamide, and other (meth)acrylamide derivatives.

[0133] The proportion of the other monomers relative to the total number of monomers constituting the anionic polymer is preferably 5 mol% or less, more preferably 1 mol% or less, and even more preferably 0.5 mol% or less.

[0134] (Physical properties of anionic polymers, etc.)

[0135] In this abrasive, the anionic polymer has an acid value of 20 mg KOH / g to 400 mg KOH / g. By using anionic polymers with an acid value below 400 mg KOH / g, the selectivity ratio of the silica film to the barrier film is improved. Furthermore, by using anionic polymers with an acid value above 20 mg KOH / g, the anionic polymer readily adsorbs onto the abrasive grains, inhibiting their aggregation. Additionally, the increased solubility of the anionic polymer further inhibits the aggregation of the anionic polymer particles themselves.

[0136] From the viewpoint of suppressing abrasive particle aggregation, the lower limit of the acid value of the anionic polymer is preferably 50 mg KOH / g, more preferably 100 mg KOH / g, and even more preferably 150 mg KOH / g. Furthermore, from the viewpoint of improving selectivity, the upper limit of the acid value of the anionic polymer is preferably 350 mg KOH / g, more preferably 300 mg KOH / g, and even more preferably 280 mg KOH / g.

[0137] It should be noted that the acid value represents the mass (mg) of potassium hydroxide required to neutralize the acidic component contained in 1g of the solid component of the polymer, and is a value determined by the method described in JIS K 0070:1992.

[0138] In the above-mentioned anionic polymer, the ratio of hydrophobic monomer to anionic monomer can be appropriately adjusted so that the acid value falls within the aforementioned range. As an example, the proportion of hydrophobic monomer relative to the total number of monomers constituting the anionic polymer is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 40 mol% or more. By making the hydrophobic monomer 10 mol% or more, the abrasion of the barrier film can be further suppressed. Furthermore, in the above-mentioned anionic polymer, the proportion of hydrophobic monomer relative to the total number of monomers is preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, and particularly preferably 80 mol% or less. By making the hydrophobic polymer 95 mol% or less, the solubility of the anionic polymer is improved, and the agglomeration of abrasive particles and the agglomeration of the anionic polymer are suppressed.

[0139] The aforementioned anionic polymer can be a random polymer in which the aforementioned hydrophobic monomer and the aforementioned anionic monomer are randomly configured, or it can be a block polymer having blocks of anionic polymer and blocks of anionic monomer.

[0140] From the perspective of storage stability, the solubility of the above-mentioned anionic polymer in water at 25°C is preferably 5 mg / 100g-H2O or more, and more preferably 10 mg / 100g-H2O or more.

[0141] From the perspective of the dispersion stability of the anionic polymer, the weight-average molecular weight (Mw) of the anionic polymer is preferably between 1,000 and 100,000. The lower limit of the weight-average molecular weight (Mw) is preferably 2,000, more preferably 2,500, and even more preferably 3,000. Furthermore, the upper limit of the weight-average molecular weight (Mw) is preferably 50,000, more preferably 40,000, even more preferably 30,000, even more preferably 25,000, particularly preferably 20,000, and extremely preferably 17,500.

[0142] The weight-average molecular weight (Mw) was determined by gel permeation chromatography (GPC) as a conversion value for standard polystyrene.

[0143] The aforementioned anionic polymers can be commercially available or synthesized. For example, in the case of random polymers, hydrophobic monomers and anionic monomers can be mixed, and an initiator can be added. Polymerization can then be carried out using known polymerization methods such as solution polymerization, bulk polymerization, and various free radical polymerizations. Solution polymerization is preferred from the perspective of easily adjusting the weight-average molecular weight of the copolymer. Furthermore, in the case of block polymers, for example, anionic blocks can be synthesized first, and then hydrophobic monomers can be polymerized onto these anionic blocks. Alternatively, the polymerization order of the anionic and hydrophobic blocks can be reversed in this manufacturing method. Alternatively, anionic and hydrophobic blocks can be synthesized separately, and then the anionic and hydrophobic blocks can be coupled together.

[0144] From the perspective of the abrasion suppression effect of the barrier film, the content of anionic polymer relative to the total mass of the abrasive is preferably 0.02% to 0.5% by mass, more preferably 0.05% to 0.45% by mass, even more preferably 0.08% to 0.4% by mass, and particularly preferably 0.1% to 0.35% by mass.

[0145] <Acidic Compounds>

[0146] This abrasive contains an acidic compound selected from phosphoric acid compounds and organic acid compounds. By including this acidic compound, the abrasion rate of the barrier film can be suppressed while maintaining the abrasion rate of the silicon oxide film. It should be noted that the molecular weight of this acidic compound is preferably 1000 or less.

[0147] Specific examples of phosphoric acid compounds include phosphoric acid, phosphorous acid, phosphonic acid, hypophosphonic acid, and their ammonium salts and alkali metal salts.

[0148] Examples of organic acid compounds include compounds having carboxyl, sulfonyl, phosphonic acid groups, and their ammonium salts, alkali metal salts, etc., with organic acid compounds having carboxyl groups being preferred.

[0149] Examples of organic acid compounds containing a carboxyl group include formic acid, acetic acid, propionic acid, and other alkyl monocarboxylic acids.

[0150] 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, pyridinecarboxylic acid, DL-piperidinecarboxylic acid, 2-furancarboxylic acid, 3-furancarboxylic acid, tetrahydrofuran-2-carboxylic acid, tetrahydrofuran-2,3,4,5-tetracarboxylic acid, and other heterocyclic carboxylic acids;

[0151] Carboxylic acids with alicyclic rings, such as cyclopentane carboxylic acid, cyclohexane carboxylic acid, cycloheptane carboxylic acid, and cyclohexyl carboxylic acid;

[0152] Alanine, glycine, glycylglycine, aminobutyric acid, N-acetylglycine, N,N-di(2-hydroxyethyl)glycine, N-(tert-butoxycarbonyl)glycine, proline, trans-4-hydroxy-L-proline, phenylalanine, sarcosine, hyaluronic acid, creatine, N-[tris(hydroxymethyl)methyl]glycine, glutamic acid, aspartic acid, and other carboxylic acids containing an amino group;

[0153] 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 and other carboxylic acids with hydroxyl groups;

[0154] Pyruvic acid, acetoacetic acid, levulinic acid, and other carboxylic acids (keto acids) containing a ketone group;

[0155] Oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, phthalic acid, and other dicarboxylic acids.

[0156] Of the above-mentioned organic acid compounds having a carboxyl group, dicarboxylic acid is particularly preferred.

[0157] Acidic compounds can be used alone or in combination of two or more. When a single acidic compound is used alone, it is sometimes referred to as the first acidic compound. Additionally, when there is a combination of two or more acidic compounds, the compound with the highest molar concentration among the various acidic compounds is sometimes referred to as the first acidic compound.

[0158] The proportion of the first acidic compound relative to the total amount of the acidic compound is preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more.

[0159] The acid dissociation constant pKa of the first acidic compound is preferably 4 to 9, more preferably 4.5 to 7, and even more preferably 5 to 6.5. By using an acidic compound with an acid dissociation constant of 4 to 9 as the first acidic compound, it is easy to prepare an abrasive that satisfies the relationship of formula (1) described later, and it is easy to improve the selectivity. When the acidic compound has more than two acid dissociation constants, it is sufficient that at least one acid dissociation constant is 4 to 9. The acid dissociation constant can be determined by neutralization titration or by referring to literature values.

[0160] This abrasive uses an abrasive in which the pKa of the first acidic compound and the pH of the abrasive satisfy the relationship of formula (1).

[0161] |pKa-pH|≤1.5・・・(1)

[0162] When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

[0163] By using an abrasive with an absolute difference between pKa and pH of 1.5 or less, a high selectivity ratio between the silica film and the barrier film can be obtained, exhibiting excellent storage stability and suppressing changes in pH and viscosity even during long-term storage. It should be noted that the inventors speculate that the first acidic compound, which has the highest concentration among the acidic compounds, has a significant impact on the aforementioned effects, and that a pKa value referencing the first acidic compound is appropriate.

[0164] From the perspective of further improving the selectivity of the abrasive, |pKa-pH| is preferably 1.2 or less, more preferably 1.0 or less, even more preferably 0.9 or less, even more preferably 0.8 or less, particularly preferably 0.7 or less, extremely preferably 0.6 or less, and most preferably 0.5 or less.

[0165] In addition to adjusting the pKa by selecting a first acidic compound, other methods for preparing abrasives that satisfy formula (1) include adjusting the pH by adjusting the concentration of the first acidic compound, adding acidic compounds other than the first acidic compound, or other pH adjusters.

[0166] The proportion of acidic compounds in the abrasive is preferably 0.001% to 2.0% by mass, more preferably 0.005% to 1.0% by mass, and even more preferably 0.01% to 0.3% by mass, relative to the abrasive as a whole.

[0167] <Water>

[0168] This abrasive contains water as a medium for dispersing the abrasive particles. The type of water is not particularly limited, but considering its impact on other components, prevention of impurity contamination, and effects on pH, pure water, ultrapure water, or ion-exchanged water are preferred.

[0169] <Nonionic polymers>

[0170] Furthermore, this abrasive may contain a nonionic polymer. From a lubrication perspective, nonionic polymers with ether bonds are preferred, and nonionic polymers with ether bonds in their main chain are more preferred. Specific examples of nonionic polymers include polyethylene glycol, polyglycerol, and water-soluble nylon.

[0171] When using a nonionic polymer, its content relative to the entire abrasive compound can be 0.005% to 2.0% by mass, preferably 0.01% to 1.5% by mass, and more preferably 0.01% to 0.3% by mass. If the content of the nonionic polymer is within the above range, the wettability of the abrasive compound on the surface being polished is improved, the contact frequency of the abrasive particles is increased, and therefore the polishing speed of the silicon oxide film is increased.

[0172] <Additives>

[0173] This abrasive may further contain various additives. Examples of such additives include pH adjusters, dispersants, anti-coagulants, lubricants, thickeners, viscosity enhancers, and preservatives; more than two additives may be included. It should be noted that the aforementioned phosphoric acid compounds and organic acid compounds may also be included in the pH adjuster, but are not considered to be included in the pH adjuster in this disclosure.

[0174] (pH adjuster)

[0175] To adjust the pH to a specified value, a pH adjuster may be included. As a pH adjuster, it is appropriate to select from acidic compounds (excluding phosphoric acid compounds and organic acid compounds), basic compounds, amphoteric compounds such as amino acids, and their salts.

[0176] Examples of acidic compounds other than phosphoric acid compounds and organic acid compounds include inorganic acids or their salts. Examples of inorganic acids include nitric acid, sulfuric acid, and hydrochloric acid, and their ammonium salts, sodium salts, potassium salts, etc. When using inorganic acids, it is preferable to use them within a range where the molar concentration in the abrasive is not higher than the molar concentration of the aforementioned first acidic compound.

[0177] Examples of basic compounds include ammonia, sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium carbonate, sodium carbonate, ammonium carbonate; quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and amino alcohols such as monoethanolamine, diethanolamine, and triethanolamine.

[0178] In addition, glycine, alanine, and phenylalanine are examples of amphoteric compounds.

[0179] The pH adjuster can be used alone or in combination of two or more. The pH of this abrasive is preferably 4 to 9. As a lower limit of pH, 4.5 is more preferred, 5 is even more preferred, and 6 is particularly preferred. Furthermore, as an upper limit of pH, 8.5 is preferred, 8 is more preferred, 7.5 is even more preferred, and 7 is particularly preferred. By adjusting the pH to the above range, abrasive particle aggregation can be suppressed, and the selectivity can be improved.

[0180] The proportion of the pH adjuster can be appropriately adjusted to achieve the pH described above. As an example, relative to the entire abrasive, it can be 0.005% to 2.0% by mass, preferably 0.01% to 1.5% by mass, and more preferably 0.01% to 0.3% by mass.

[0181] (Dispersant)

[0182] To improve the dispersibility of abrasive particles, this abrasive may contain a dispersant. Examples of dispersants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants; one or more of these may be used.

[0183] As an anionic surfactant, polymers having carboxyl groups or ammonium carboxylate salts are preferred, and polyacrylic acid or polyacrylate is more preferred.

[0184] Examples of cationic surfactants include diallyl dimethyl ammonium chloride polymer, diallyl dimethyl ammonium chloride-sulfur dioxide copolymer, diallyl dimethyl ammonium chloride-acrylamide copolymer, diallyl dimethyl ammonium chloride-maleic acid copolymer, and maleic acid-diallyl dimethyl ammonium ethyl sulfate-sulfur dioxide copolymer.

[0185] From the viewpoint of grinding the surface at a higher speed, the weight-average molecular weight of the surfactant is preferably 10,000 to 100,000.

[0186] When using a dispersant, from the viewpoint of grinding the surface at a higher speed, its content relative to the total mass of the above-mentioned abrasive is preferably 0.0001% to 0.3% by mass, more preferably 0.001% to 0.2% by mass, and even more preferably 0.01% to 0.15% by mass.

[0187] In this abrasive, when the above-mentioned additives are used, from the viewpoint of obtaining an abrasive with a high selectivity ratio of silicon oxide film to barrier film, the total content of the additives relative to the total mass of the above-mentioned abrasive is preferably 0.01% to 10.0% by mass, more preferably 0.01% to 5.0% by mass.

[0188] The preparation method of this abrasive can be appropriately selected from methods that uniformly disperse or dissolve the abrasive particles, anionic polymers, acidic compounds, and other components as needed in water as a medium.

[0189] For example, this abrasive can be prepared by separately preparing a dispersion of abrasive particles and an additive solution for abrasives (described later), and then mixing them. According to this method, the dispersion and the additive solution for abrasives exhibit excellent storage stability and ease of transport.

[0190] This abrasive is preferably prepared temporarily by mixing as described above within a grinding apparatus.

[0191] [Abrasive additive]

[0192] The abrasive additive solution of this embodiment is an additive solution used to prepare an abrasive by mixing with the dispersion of abrasive particles as described above. It is an abrasive additive solution comprising an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water.

[0193] The aforementioned anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers.

[0194] The acid values ​​of the above-mentioned anionic polymers range from 20 mg KOH / g to 400 mg KOH / g.

[0195] The partition coefficients (logD) of the aforementioned hydrophobic monomers range from 0 to 4.

[0196] The aforementioned anionic monomers include at least one selected from unsaturated monocarboxylic acids and their salts.

[0197] When the acidic compound with the highest molar concentration among the above acidic compounds is designated as the first acidic compound,

[0198] The pKa of the first acidic compound and the pH of the abrasive additive solution satisfy the relationship of formula (1) above. The abrasive may also contain the described additives as other components as needed. These components are described above, therefore their description is omitted here.

[0199] It should be noted that when preparing an abrasive by mixing two liquids—a dispersion of abrasive particles and an additive for abrasives—the concentration of the abrasive particles in the dispersion and the concentration of the anionic polymer and acidic compound in the additive for abrasives can be pre-concentrated to 2 to 100 times the concentration required for use, and then diluted to the specified concentration before use. More specifically, for example, when the concentration of the abrasive particles in the dispersion and the concentration of the anionic polymer and acidic compound in the additive are both concentrated to 10 times, the abrasive is prepared by mixing and stirring in a ratio of 10 parts by mass of dispersion, 10 parts by mass of additive for abrasives, and 80 parts by mass of water.

[0200] By adding the above-mentioned abrasive additive to the dispersion of abrasive particles, an abrasive can be obtained that maintains a high abrasive speed of silicon oxide film while suppressing a low abrasive speed of barrier film, and achieves high selectivity and flatness.

[0201] In the above-mentioned abrasive additive solution, the content (concentration) of anionic polymer is preferably 0.001 to 30% by mass of the total additive solution, more preferably 0.01 to 20% by mass, and even more preferably 0.1 to 10% by mass.

[0202] In addition, the abrasive particles in the above-mentioned dispersion are preferably 0.2 to 40% by mass, more preferably 1 to 20% by mass, and even more preferably 5 to 10% by mass.

[0203] [Grinding method]

[0204] The polishing method disclosed herein is a polishing method in which polishing is performed by supplying polishing agent while bringing the surface to be polished into contact with polishing pad, and polishing is performed by the relative movement of the two. The polishing agent disclosed herein is used as the polishing agent to polish the silicon oxide-containing surface of a semiconductor substrate.

[0205] Here, examples of the surface to be polished include the surface of a semiconductor substrate containing a surface made of silicon dioxide, a blank wafer formed by stacking a barrier film and a silicon oxide film on the surface of a semiconductor substrate, and a patterned wafer in which these films are arranged in a pattern. As a semiconductor substrate, a substrate used in STI is a preferred example. The polishing agent disclosed herein is also effective for planarizing interlayer insulating films used between multilayer wirings in the manufacture of semiconductor devices.

[0206] Examples of silicon oxide films used in STI substrates include PE-TEOS films formed by plasma CVD using tetraethoxysilane (TEOS) as a raw material. HDP films, formed by high-density plasma CVD, are also examples of silicon oxide films. HARP films, FCVD films, and SOD films formed by spin coating, formed by other CVD methods, can also be used. Examples of silicon nitride films include those formed by low-pressure CVD, plasma CVD, and ALD, using silane or dichlorosilane and ammonia as raw materials. Polycrystalline silicon films include those formed by low-pressure CVD or plasma CVD followed by heat treatment to produce polycrystalline granular films.

[0207] This grinding method can use known grinding apparatus. Figure 2 This is a schematic diagram illustrating an example of a grinding apparatus. Figure 2The polishing apparatus 20 shown in the example includes: a polishing head 22 for holding a semiconductor substrate 21 such as an STI substrate, a polishing platform 23, an polishing pad 24 attached to the surface of the polishing platform 23, and an polishing agent supply pipe 26 for supplying polishing agent 25 to the polishing pad 24. It is configured such that, while supplying polishing agent 25 from the polishing agent supply pipe 26, the surface of the semiconductor substrate 21 held by the polishing head 22 is brought into contact with the polishing pad 24, and the polishing head 22 and the polishing platform 23 rotate relative to each other to perform polishing.

[0208] The polishing head 22 can perform both rotary and linear motion. Furthermore, the polishing platform 23 and polishing pad 24 can be the same size as or smaller than the semiconductor substrate 21. In this case, it is preferable to polish the entire surface of the semiconductor substrate 21 by moving the polishing head 22 relative to the polishing platform 23. Alternatively, the polishing platform 23 and polishing pad 24 may not rotate; for example, they may move in a belt-like manner in one direction.

[0209] The polishing conditions of this 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 and polishing speed can be further increased. The polishing pressure is preferably about 0.5 to 50 kPa, and from the viewpoint of improving the uniformity and flatness of the polished surface of the semiconductor substrate 21 at the polishing speed and preventing polishing defects such as scratches, it is more preferably about 3 to 40 kPa. The rotational speed of the polishing platform 23 and the polishing head 22 is preferably about 50 to 500 rpm. In addition, the supply amount of polishing flux 25 is appropriately adjusted according to the composition of the polishing flux and the above-mentioned polishing conditions.

[0210] The abrasive pad 24 can be made of non-woven fabric, polyurethane foam, porous resin, or non-porous resin. To facilitate the supply of abrasive 25 to the abrasive pad 24, or to accumulate a certain amount of abrasive 25 on the abrasive pad 24, grooves such as grids, concentric circles, or spirals can be formed on the surface of the abrasive pad 24. Furthermore, the pad adjuster can be brought into contact with the surface of the abrasive pad 24 as needed, and abrasion can be performed while adjusting the surface of the abrasive pad 24.

[0211] According to this polishing method, a high selectivity ratio of silicon oxide film to barrier film can be obtained while suppressing polishing scratches, thus achieving polishing with high flatness.

[0212] [Manufacturing methods for semiconductor components]

[0213] The semiconductor component manufacturing method of this embodiment obtains a semiconductor component by monolithically processing a semiconductor substrate having a polished surface polished by the polishing method disclosed above.

[0214] The semiconductor component manufacturing method disclosed herein includes at least a monolithization step: monolithizing a semiconductor substrate having a polished surface polished by the above-described polishing method. Examples of the monolithization step include, for instance, cutting the semiconductor substrate (e.g., a semiconductor wafer) using known methods such as blade cutting, laser cutting, or plasma cutting to obtain a semiconductor component that serves as a semiconductor chip.

[0215] The method for manufacturing this semiconductor component may further include a bonding step: bonding other components onto the polished surface of the aforementioned semiconductor chip. Through this step, a semiconductor component as a bond is obtained.

[0216] Other components may include a second semiconductor chip, a redistribution layer, etc. It should be noted that the second semiconductor chip may be a semiconductor chip obtained by the manufacturing method of this disclosure, or a semiconductor chip obtained by other methods. As for the aforementioned bonding process, it may be a process of directly bonding other components by directly placing them on the polished surface, such as by fusion bonding or surface activation bonding, or it may be a process of bonding the polished surface to other components via an adhesive layer. Examples of adhesive layers include solder, metal layers such as copper, glass layers, resin layers such as polyimide and epoxy, etc.

[0217] This disclosure may further provide an electronic device comprising at least one semiconductor component having a polished surface polished by the polishing method of this disclosure.

[0218] Example

[0219] The present invention will now be specifically described through examples and comparative examples, but the present invention is not limited to these examples. Examples 1 to 8 are examples, and Examples 9 to 14 are comparative examples.

[0220] [Measurement Method]

[0221] <pH>

[0222] The pH was measured using a pH meter HM-30R manufactured by DKK Corporation of East Asia, with the temperature set to 25±5℃.

[0223] <Average secondary particle size>

[0224] The average secondary particle size was measured using a laser scattering and diffraction particle size distribution measuring device (manufactured by Horiba Corporation, device name: LA-950).

[0225] <Acid Value>

[0226] The determination was performed using the method described in JIS K 0070:1992.

[0227] <Weight-average molecular weight (Mw)>

[0228] The determination was performed using gel permeation chromatography (GPC) under the following conditions.

[0229] • Device HLC-8320GPC (Tosoh Corporation)

[0230] • Pillar TSKgel GMPWXL (Tosoh Manufacturing)

[0231] • Detector RI Detector polarity (+)

[0232] • Eluent 0.2M NaNO3 aqueous solution

[0233] • Flow rate 1.0 mL / min, column temperature 40 °C

[0234] • Calculated using standard PEO / PEG conversion

[0235] [Abrasive]

[0236] <Abrasive>

[0237] Cerium oxide particles with a particle size of 50–150 nm are used as abrasives. The cerium oxide content in the cerium oxide particles is 95% by mass or more.

[0238] <Anionic polymers>

[0239] Prepare an anionic polymer with the following composition.

[0240] • Anionic polymer (A): A polymer consisting of 70 mol% n-butyl methacrylate (logD = 2.6) and 30 mol% methacrylic acid, with an acid value of 150 mg KOH / g and a weight-average molecular weight of 20,000.

[0241] • Anionic polymer (B): A polymer consisting of 50 mol% n-butyl methacrylate and 50 mol% methacrylic acid, with an acid value of 250 mg KOH / g and a weight-average molecular weight of 20,000.

[0242] • Anionic polymer (C): A polymer consisting of 50 mol% n-butyl methacrylate and 50 mol% methacrylic acid, with an acid value of 250 mg KOH / g and a weight-average molecular weight of 15,000.

[0243] • Anionic polymer (D): A homopolymer of methacrylic acid with an acid value of 650 mg KOH / g and a weight-average molecular weight of 10,000.

[0244] • Anionic polymer (E): A polymer consisting of 10 mol% n-butyl methacrylate and 90 mol% methacrylic acid, with an acid value of 510 mg KOH / g and a weight-average molecular weight of 20,000.

[0245] • Anionic polymer (F): A polymer consisting of 30 mol% decyl methacrylate (logD of 5.9) and 70 mol% methacrylic acid, with an acid value of 300 mg KOH / g and a weight-average molecular weight of 40,000.

[0246] <Preparation of Abrasive>

[0247] As shown in Table 1, abrasives of Examples 1 to 14 were prepared by mixing abrasive particles, anionic polymers, acidic compounds, other components, and water. In each abrasive, the zeta potential of the abrasive particles ranged from -80 mV to -50 mV. It should be noted that the acidic compound was adjusted to account for pH within the range of 0.01% to 0.3% by mass. Additionally, “-” in Table 1 indicates that it was not used.

[0248] [Grinding Evaluation]

[0249] <Grinding conditions>

[0250] The performance of the abrasives used in Examples 1 to 14 was evaluated using a fully automated CMP apparatus, FREX300X (manufactured by Ebara Corporation). In the evaluation, a polyurethane pad (DuPont IC-1000) was used as the abrasive pad, and a diamond pad adjuster (3M A165) was used for adjustment. The abrasive conditions were set at a pressure of 21 kPa, a platform speed of 100 rpm, and a head speed of 102 rpm. Unless otherwise specified, the abrasive feed rate was 250 ml / min.

[0251] The following substances are used as the object to be ground (the material being ground).

[0252] • Patternless wafers with a silicon dioxide film formed on a 12-inch silicon substrate using tetraethoxysilane (TEOS) as a raw material via plasma CVD.

[0253] • Patternless wafers with silicon nitride films formed on 12-inch silicon substrates using silane and ammonia as raw materials via low-pressure CVD.

[0254] <Evaluation Methods>

[0255] The thicknesses of the silicon dioxide and silicon nitride films were measured using a SCREEN VM-3210 thickness gauge. The polishing speeds of the silicon dioxide and silicon nitride films were calculated by determining the difference between the film thickness before polishing and the film thickness after one minute of polishing on each unpatterned wafer. The average polishing speed (Å / min) obtained from the polishing speed at 49 points in-plane of the substrate was calculated as the polishing speed, and the ratio of the polishing speed of the silicon dioxide film to that of the silicon nitride film (silicon dioxide polishing speed / silicon nitride polishing speed) was calculated as the selection ratio. The results are shown in Table 1. It should be noted that in the table, silicon oxide is labeled "TEOS" and silicon nitride is labeled "SiN".

[0256] [Stability Evaluation]

[0257] For the grinding media of Examples 1 to 14, the pH was measured after storage at 50°C for 2 weeks. The difference between the pH of the freshly prepared grinding media and the pH after storage is shown in Table 1.

[0258]

[0259] The abrasives of Examples 1-8, containing abrasive particles, a specific anionic polymer, and a specific acidic compound, and satisfying |pKa-pH| ≤ 1.5, exhibited high grinding speeds for silicon oxide films and suppressed grinding speeds for silicon nitride films, resulting in high selectivity. Furthermore, the abrasives of Examples 1-7 showed excellent pH and viscosity stability, maintaining stable performance. The abrasives of Examples 7 and 8, further containing nonionic polymers, showed even higher grinding speeds for silicon oxide films compared to the abrasive of Example 4. It is inferred that by combining nonionic polymers, the wettability of the abrasive to the surface being ground is improved, the contact frequency of the abrasive particles is increased, thereby increasing the grinding speed of the silicon oxide film.

[0260] On the other hand, the abrasives used in Examples 9 and 10, which employed anionic polymers with high acid values, showed that the abrasive speed of the silicon nitride film was not sufficiently suppressed, resulting in a reduced selectivity. For the abrasive in Example 11, which did not contain acidic compounds, the abrasive speed of the silicon oxide film decreased, and the selectivity was insufficient. Furthermore, the abrasives in Examples 12 to 14, with |pKa-pH| exceeding 1.5, exhibited problems with storage stability, making it difficult to maintain the abrasive's performance.

[0261] As can be seen from the above, the abrasive of this embodiment can maintain the abrasive speed of the silicon oxide film while suppressing the abrasive speed of the barrier film, thereby obtaining a high selectivity. In addition, this performance can be maintained for a long time.

[0262] Industrial availability

[0263] According to this disclosure, high-speed polishing can be achieved, for example, in a CMP process for polishing surfaces containing insulating films. Therefore, the polishing method of this disclosure is suitable for polishing insulating films for STI in semiconductor device manufacturing.

[0264] This application claims priority based on Japanese Patent Application No. 2023-74452, filed on April 28, 2023, the entire contents of which are incorporated herein by reference.

[0265] Symbol Explanation

[0266] 1…Silicon substrate, 2…Barrier film, 3…Trench, 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 piping.

Claims

1. An abrasive comprising abrasive particles, an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water. The anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers. The acid value of the anionic polymer is 20 mg KOH / g to 400 mg KOH / g. The partition coefficient, logD, of the hydrophobic monomer is between 0 and 4. The anionic monomer comprises at least one selected from unsaturated monocarboxylic acids and their salts. When the acidic compound with the highest molar concentration is designated as the first acidic compound, The pKa of the first acidic compound and the pH of the abrasive satisfy the relationship of equation (1). |pKa-pH|≤1.5・・・(1) in, When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

2. The abrasive according to claim 1, wherein, The abrasive particles comprise at least one selected from silica particles, alumina particles, zirconium oxide particles, cerium compound particles, titanium dioxide particles, germanium oxide particles and their composite particles, and core-shell particles.

3. The abrasive according to claim 2, wherein, The abrasive particles contain cerium compound particles.

4. The abrasive according to claim 2, wherein, The abrasive particles contain cerium oxide particles.

5. The abrasive according to claim 1, wherein, The content of the abrasive particles is 0.01% to 10.0% by mass relative to the total mass of the abrasive.

6. The abrasive according to claim 1, wherein, The acid value of the anionic polymer is 20 mg KOH / g to 300 mg KOH / g.

7. The abrasive according to claim 1, wherein, The partition coefficient, logD, of the hydrophobic monomer is 0 to 3.

8. The abrasive according to claim 1, wherein, The hydrophobic monomer comprises an alkyl (meth)acrylate.

9. The abrasive according to claim 1, wherein, The weight-average molecular weight of the anionic polymer is 1,000 to 100,000.

10. The abrasive according to claim 1, wherein, The proportion of hydrophobic monomers in the anionic polymer is 10 to 95 moles relative to all monomers constituting the anionic polymer.

11. The abrasive according to claim 1, wherein, The content of the anionic polymer is 0.02% to 0.5% by mass relative to the total mass of the abrasive.

12. The abrasive according to claim 1, wherein, The pKa is 4 to 9.

13. The abrasive according to claim 1, wherein, It further includes nonionic polymers.

14. The abrasive according to claim 1, wherein, The pH ranges from 4 to 9.

15. A polishing method comprising supplying an polishing agent while simultaneously bringing the surface of a semiconductor substrate to be polished into contact with a polishing pad, and performing polishing through the relative motion between the two surfaces. The abrasive is the abrasive according to any one of claims 1 to 14.

16. A method for manufacturing a semiconductor component, wherein the semiconductor component is obtained by monolithically processing a semiconductor substrate having a polished surface polished by the polishing method of claim 15.

17. An abrasive additive comprising an anionic polymer, an acidic compound selected from phosphoric acid compounds and organic acid compounds, and water. The anionic polymer is a copolymer comprising hydrophobic monomers and anionic monomers. The acid value of the anionic polymer is 20 mg KOH / g to 400 mg KOH / g. The partition coefficient, logD, of the hydrophobic monomer is between 0 and 4. The anionic monomer comprises at least one selected from unsaturated monocarboxylic acids and their salts. When the acidic compound with the highest molar concentration is designated as the first acidic compound, The pKa of the first acidic compound and the pH of the abrasive additive solution satisfy the relationship of equation (1). |pKa-pH|≤1.5・・・(1) in, When the first acidic compound has more than two acid dissociation constants, pKa represents the acid dissociation constant closest to pH.

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