Polishing liquid for CMP, polishing liquid set for CMP, and polishing method

Abstract

A polishing liquid for CMP containing abrasive grains, a nitrogen-containing compound having an aromatic ring, and water, wherein the abrasive grains include cerium-based particles, and the zeta potential of the abrasive grains is negative. A polishing method comprising a step for using the polishing liquid for CMP to polish a surface to be polished.

Description

CMP polishing liquid, CMP polishing liquid set, and polishing method

[0001] The present disclosure relates to a polishing liquid for CMP (chemical mechanical polishing), a polishing liquid set for CMP, a polishing method, and the like.

[0002] In the field of semiconductor manufacturing, as the performance of VLSI devices improves, it is becoming increasingly difficult to achieve both high integration and high speed through miniaturization technology, which is an extension of conventional technology. Therefore, technologies that enable vertical integration (i.e., multi-layer wiring technology) are being developed while continuing to miniaturize semiconductor elements.

[0003] CMP is one of the most important technologies in the process of manufacturing devices with multi-layered wiring. CMP is a technology for planarizing the surface of a substrate obtained by forming a thin film on the substrate by chemical vapor deposition (CVD) or the like. For example, planarization processing by CMP is essential to ensure the depth of focus in lithography. If the surface of the substrate is uneven, it can cause inconveniences such as making it impossible to focus in the exposure process or making it impossible to form a fine wiring structure satisfactorily. CMP is also used in the device manufacturing process to planarize the surface of a plasma oxide film (BPSG, HDP-SiO ２ The method is also applicable to a process for forming an isolation region (inter-element isolation; STI: shallow trench isolation) by polishing a silicon dioxide film (SiO2, p-TEOS, etc.); a process for forming an ILD film (an interlayer insulating film that electrically insulates metal members (wiring, etc.) in the same layer); and a process for planarizing a plug (e.g., an Al / Cu plug) after embedding a film containing silicon oxide in a metal wiring.

[0004] CMP is typically performed using an apparatus capable of supplying a polishing liquid onto a polishing pad. The surface of the substrate is polished by pressing the substrate against the polishing pad while supplying the polishing liquid between the surface of the substrate and the polishing pad. Thus, the polishing liquid is one of the key technologies in CMP technology, and various polishing liquids have been developed to obtain high-performance polishing liquids (see, for example, Patent Document 1 below).

[0005] Among the processes to which the above-mentioned CMP technology is applied, the CMP process of an ILD film, in particular, requires the polishing of silicon oxide at a high polishing rate. Therefore, silica-based polishing solutions (polishing solutions using abrasive grains containing silica-based particles) that have a high polishing rate are primarily used in the CMP process of an ILD film (see, for example, Patent Document 2 below). However, with silica-based polishing solutions, it tends to be difficult to control polishing scratches, which are the cause of defects. Furthermore, with the recent trend toward finer interconnects, it is desirable to reduce polishing scratches in the CMP process of an ILD film. However, unlike the CMP process of an insulating film for an isolation region, finishing mirror polishing is generally not performed. Therefore, the use of cerium-based polishing solutions (polishing solutions using abrasive grains containing cerium-based particles), which have fewer polishing scratches than silica-based polishing solutions, has been considered (see, for example, Patent Document 3 below).

[0006] JP 2008-288537 JP 9-316431 JP 10-102038

[0007] When polishing a surface to be polished using abrasive grains, it is required that the abrasive grains are unlikely to remain on the surface to be polished after polishing. Here, silicon oxide, which is a material to be polished, tends to have a negative zeta potential. Therefore, when polishing a surface to be polished containing silicon oxide using abrasive grains having a negative zeta potential, the abrasive grains are unlikely to remain on the surface to be polished after polishing due to electrostatic repulsion between the abrasive grains and the surface to be polished. On the other hand, since the electrostatic repulsion between the abrasive grains and the surface to be polished makes it difficult to increase the polishing rate, it may be difficult to achieve a high polishing rate for silicon oxide when using abrasive grains having a negative zeta potential.

[0008] Furthermore, CMP polishing liquids can be used to polish a patterned wafer having a concave-convex pattern composed of convex portions (e.g., line portions) and concave portions (e.g., space portions) to remove the convex portions, thereby planarizing the polished surface. In this case, from the viewpoint of obtaining high flatness and shortening the polishing time required for planarization, it may be necessary to achieve a high polishing rate ratio of silicon oxide in the convex portions of the patterned wafer having the concave-convex pattern to silicon oxide in a blanket wafer not having the concave-convex pattern. However, when abrasive grains having a negative zeta potential are used, it may be difficult to achieve such a high polishing rate ratio due to factors such as the electrostatic repulsion between the abrasive grains and the convex portions making it difficult to increase the polishing rate.

[0009] One aspect of the present disclosure aims to provide a CMP polishing liquid that uses abrasive grains having a negative zeta potential and that can achieve a high removal rate ratio of silicon oxide on convex portions of a patterned wafer having a concave-convex pattern relative to silicon oxide on a blanket wafer without a concave-convex pattern. Another aspect of the present disclosure aims to provide a CMP polishing liquid set for obtaining the CMP polishing liquid. Yet another aspect of the present disclosure aims to provide a polishing method using the CMP polishing liquid.

[0010] In some aspects, the present disclosure relates to the following items [1] to

[15] . [1] A polishing slurry for CMP containing abrasive grains, a nitrogen-containing compound having an aromatic ring, and water, wherein the abrasive grains include cerium-based particles and the abrasive grains have a negative zeta potential. [2] The polishing slurry for CMP according to [1], wherein the cerium-based particles include cerium oxide. [3] The polishing slurry for CMP according to [1] or [2], wherein the nitrogen-containing compound includes a compound having an amino group bonded to an aromatic ring. [4] The polishing slurry for CMP according to [3], wherein the nitrogen-containing compound includes anthranilic acid. [5] The polishing slurry for CMP according to any one of [1] to [4], wherein the nitrogen-containing compound includes a compound having a hydroxyamide group bonded to an aromatic ring. [6] The polishing slurry for CMP according to [5], wherein the nitrogen-containing compound includes benzohydroxamic acid. [7] The polishing slurry for CMP according to any one of [1] to [6], wherein the nitrogen-containing compound includes an indole compound. [8] The CMP polishing slurry according to [7], wherein the nitrogen-containing compound comprises indoleacetic acid. [9] The CMP polishing slurry according to any one of [1] to [8], wherein the nitrogen-containing compound comprises a quinoline compound.

[10] The CMP polishing slurry according to [9], wherein the nitrogen-containing compound comprises quinaldic acid.

[11] The CMP polishing slurry according to any one of [1] to

[10] , wherein the nitrogen-containing compound is present in an amount of 0.001 to 5 mass%.

[12] The CMP polishing slurry according to any one of [1] to

[11] , wherein the pH is 4.0 to 9.0.

[13] A CMP polishing slurry set, wherein the components of the CMP polishing slurry according to any one of [1] to

[12] are stored separately as a first liquid and a second liquid, the first liquid containing the abrasive grains and water, and the second liquid containing the nitrogen-containing compound and water.

[14] A polishing method comprising a step of polishing a surface to be polished using the polishing slurry for CMP according to any one of [1] to

[12] .

[15] The polishing method according to

[14] , wherein the surface to be polished contains silicon oxide.

[0011] According to one aspect of the present disclosure, there is provided a CMP polishing liquid that uses abrasive grains having a negative zeta potential and that can achieve a high removal rate ratio of silicon oxide on convex portions of a patterned wafer having a concave-convex pattern relative to silicon oxide on a blanket wafer not having a concave-convex pattern. According to another aspect of the present disclosure, there is provided a CMP polishing liquid set for obtaining the CMP polishing liquid. According to yet another aspect of the present disclosure, there is provided a polishing method using the CMP polishing liquid.

[0012] 1A to 1C are schematic cross-sectional views showing a process of polishing an ILD film.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail.

[0014] In this specification, numerical ranges indicated using "to" indicate a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. A numerical range "A or greater" means a range exceeding A and A. A numerical range "A or less" means a range less than A and A. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. The term "layer" or "film" encompasses not only a structure having a shape formed over the entire surface when observed in a plan view, but also a structure having a shape formed on a portion of the surface. The term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0015] <CMP Polishing Slurry> The CMP polishing slurry according to this embodiment (hereinafter sometimes simply referred to as the "polishing slurry") contains abrasive grains, a nitrogen-containing compound having an aromatic ring (hereinafter sometimes referred to as the "nitrogen-containing aromatic compound"), and water. The abrasive grains include cerium-based particles (particles containing a cerium-based compound), and the abrasive grains have a negative zeta potential.

[0016] The polishing liquid of this embodiment can achieve a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer having a concave-convex pattern (a concave-convex pattern consisting of convex portions (e.g., line portions) and concave portions (e.g., space portions)) relative to silicon oxide on a blanket wafer not having a concave-convex pattern. For example, a high polishing rate ratio of silicon oxide on the convex portions in a region of the patterned wafer where L / S = 20 μm / 80 μm is achieved relative to silicon oxide on a blanket wafer not having a concave-convex pattern. The polishing liquid of this embodiment can achieve a polishing rate ratio of silicon oxide on the convex portions in a region of the patterned wafer where L / S = 20 μm / 80 μm is achieved relative to silicon oxide on a blanket wafer in an evaluation method described in the Examples below, of, for example, 0.70 or more (preferably, 0.90 or more, 1.00 or more, 1.50 or more, 1.70 or more). By obtaining a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer having a concave-convex pattern to silicon oxide on a blanket wafer not having a concave-convex pattern, it is possible to realize a high degree of flatness as a property that allows the convex portions to be selectively polished.

[0017] The factors that enable a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer are not entirely clear, but are presumed to be as follows. However, the factors are not limited to the following. That is, when a polishing surface containing silicon oxide is polished using abrasive grains with a negative zeta potential, it may be difficult to achieve a high polishing rate of silicon oxide due to electrostatic repulsion between the abrasive grains and the polishing surface. In particular, with a patterned wafer, although high pressure is easily applied to the convex portions, it may be difficult to obtain a polishing rate corresponding to the pressure applied to the convex portions. On the other hand, with the polishing liquid according to this embodiment, the use of a nitrogen-containing aromatic compound together with cerium-based particles increases the interaction between the cerium-based particles and the silicon oxide on the convex portions (e.g., the chemical reaction (reaction resulting from Si—O—Ce bonds) between the cerium-based particles in the polishing liquid and the silicon oxide on the convex portions is likely to be promoted), and the absolute value of the negative charge on the polishing surface containing silicon oxide is reduced, thereby easily suppressing the electrostatic repulsion between the abrasive grains and the polishing surface. Therefore, when polishing a patterned wafer, it is easy to obtain a polishing rate that corresponds to the pressure applied to the convex portions, making it possible to achieve a high polishing rate for silicon oxide on the convex portions, and it is presumed that a high polishing rate ratio for silicon oxide on the convex portions of a patterned wafer relative to silicon oxide on a blanket wafer can be achieved.

[0018] According to the findings of the present inventors, even if a high removal rate of silicon oxide is achieved when polishing a blanket wafer without a concave-convex pattern using abrasive grains having a negative zeta potential, it may be difficult to achieve a high removal rate of silicon oxide on the convex portions when polishing a patterned wafer having a concave-convex pattern. Therefore, a polishing liquid using abrasive grains having a negative zeta potential may be required to achieve a high removal rate of silicon oxide on the convex portions when polishing a patterned wafer having a concave-convex pattern. According to one aspect of the polishing liquid of this embodiment, a high removal rate of silicon oxide on the convex portions can be achieved when polishing a patterned wafer having a concave-convex pattern, and for example, a high removal rate of silicon oxide on the convex portions can be achieved when polishing a patterned wafer having a line / space (L / S) = 20 μm / 80 μm region of the patterned wafer. According to one aspect of the polishing liquid of this embodiment, in the evaluation method described in the Examples below, a polishing rate of silicon oxide on the convex portions in the region of L / S = 20 μm / 80 μm of, for example, 100 nm / min or more (preferably, 150 nm / min or more, 200 nm / min or more, 250 nm / min or more, 300 nm / min or more, 350 nm / min or more, etc.) can be obtained.

[0019] According to one aspect of the polishing liquid of this embodiment, high-speed polishing of silicon oxide can be achieved on a blanket wafer that does not have a concave-convex pattern, while a high polishing rate of silicon oxide on convex portions can be achieved when polishing a region of a patterned wafer where L / S = 20 μm / 80 μm. According to one aspect of the polishing liquid of this embodiment, a polishing rate of silicon oxide on a blanket wafer of, for example, 40 nm / min or more (preferably 50 nm / min or more, 80 nm / min or more, 100 nm / min or more, 150 nm / min or more, 200 nm / min or more, 230 nm / min or more) can be obtained in the evaluation method described in the Examples below.

[0020] In the process of forming an isolation region, it may be necessary to suppress the polishing rate of a silicon nitride film used as a stopper underlying a silicon oxide film, and a high polishing selectivity of silicon oxide relative to silicon nitride (polishing rate of silicon oxide / polishing rate of silicon nitride) may be required. According to one aspect of the polishing liquid of this embodiment, a sufficiently low polishing rate of silicon nitride can be obtained, and a high polishing selectivity of silicon oxide relative to silicon nitride can be obtained. This is suitable for polishing when forming an isolation region. According to one aspect of the polishing liquid of this embodiment, in the evaluation method described in the Examples below, a polishing rate of silicon nitride on a blanket wafer of, for example, 100 nm / min or less (preferably 50 nm / min or less, 30 nm / min or less, 20 nm / min or less, 15 nm / min or less, etc.) can be obtained.

[0021] The polishing liquid according to this embodiment can be used in CMP of semiconductor wafer materials, for example, to polish a silicon oxide film formed on the surface of a semiconductor wafer. The polishing liquid according to this embodiment can be used in the CMP process of an ILD film. According to one aspect of the polishing liquid according to this embodiment, a high polishing rate can be achieved, abrasive aggregation and the occurrence of polishing scratches can be suppressed, and high flatness can be obtained.

[0022] (Abrasive grains) In the polishing liquid according to this embodiment, the abrasive grains contain cerium-based particles (particles containing a cerium-based compound). By using cerium-based particles as the abrasive grains, it is easy to obtain a high removal rate of silicon oxide on the convex portions of a patterned wafer while reducing polishing scratches on the polished surface.

[0023] Examples of the cerium-based compound of the cerium-based particles include cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, and cerium carbonate. The cerium-based particles may contain cerium oxide from the viewpoint of easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer (such as convex portions in the region of L / S=20 μm / 80 μm; the same applies below) and from the viewpoint of easily obtaining a polished surface with few polishing scratches and excellent flatness. The cerium oxide is CeO ２ (cerium (IV) oxide, ceria), and Ce ２ O ３ (cerium(III) oxide).

[0024] The cerium oxide particles (particles containing cerium oxide) may contain polycrystalline cerium oxide having grain boundaries. The particles containing polycrystalline cerium oxide have the property of becoming finer during polishing and simultaneously revealing active surfaces one after another, thereby enabling a high polishing rate of silicon oxide on the convex portions of a patterned wafer to be maintained at a high level.

[0025] Methods for producing cerium oxide particles include a calcination method and an oxidation method using hydrogen peroxide or the like. When calcining, the temperature during calcination may be 350 to 900°C. When the cerium oxide particles are aggregated, the particles may be mechanically pulverized. The pulverization method may be, for example, dry pulverization using a jet mill or the like, or wet pulverization using a planetary bead mill or the like. As the jet mill, for example, the one described in "Chemical Engineering Journal," Vol. 6, No. 5, (1980), pp. 527-532, can be used.

[0026] The zeta potential (surface potential) of the abrasive grains in the polishing liquid is negative (the zeta potential is less than 0 mV). The zeta potential of the abrasive grains may be -1 mV or less, -5 mV or less, -10 mV or less, -20 mV or less, -30 mV or less, -40 mV or less, -45 mV or less, -50 mV or less, or -55 mV or less. The zeta potential of the abrasive grains may be -100 mV or more, -90 mV or more, -80 mV or more, -70 mV or more, -60 mV or more, -55 mV or more, -50 mV or more, or -45 mV or more. From these viewpoints, the zeta potential of the abrasive grains may be −100 mV or more and less than 0 mV, −80 mV or more and less than 0 mV, −60 mV or more and less than 0 mV, −100 mV to −20 mV, −80 mV to −20 mV, −60 mV to −20 mV, −100 mV to −40 mV, −80 mV to −40 mV, or −60 mV to −40 mV.

[0027] The zeta potential of the abrasive grains can be measured, for example, using a dynamic light scattering zeta potential measuring device (e.g., DelsaNano C, manufactured by Beckman Coulter, Inc.). The zeta potential of the abrasive grains can be adjusted using additives. For example, abrasive grains with a negative zeta potential can be obtained by contacting the abrasive grains with an anionic dispersant. Examples of anionic dispersants include polymers having at least one selected from the group consisting of a carboxy group and a carboxylate group; ammonium dihydrogen phosphate, etc. Examples of polymers having at least one selected from the group consisting of a carboxy group and a carboxylate group include ammonium polyacrylate, polyacrylic acid, a copolymer of acrylic acid and an alkyl acrylate, a copolymer of acrylic acid and methacrylic acid, and salts thereof. The polishing liquid according to this embodiment may contain, as an anionic dispersant in contact with the abrasive grains, a polymer having at least one selected from the group consisting of a carboxy group and a carboxylate group, and at least one selected from the group consisting of ammonium dihydrogen phosphate, from the viewpoints of easily obtaining a high removal rate for silicon oxide on the convex portions of a patterned wafer, easily achieving a high removal rate ratio for silicon oxide on the convex portions of a patterned wafer relative to silicon oxide on a blanket wafer, and easily suppressing the removal rate for silicon nitride.

[0028] The average particle size of the abrasive grains may be 50 nm or more, 70 nm or more, 80 nm or more, 100 nm or more, more than 100 nm, 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, 130 nm or more, 135 nm or more, or 140 nm or more, from the viewpoint of easily achieving a high removal rate of silicon oxide on the convex portions of a patterned wafer and from the viewpoint of easily achieving high-speed polishing of silicon oxide on a blanket wafer having no uneven pattern. The average particle size of the abrasive grains may be 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 180 nm or less, 150 nm or less, or 140 nm or less, from the viewpoint of easily suppressing the occurrence of polishing scratches. From these viewpoints, the average particle size of the abrasive grains may be 50 to 500 nm, 50 to 200 nm, 50 to 150 nm, 70 to 500 nm, 70 to 200 nm, 70 to 150 nm, 100 to 500 nm, 100 to 200 nm, or 100 to 150 nm.

[0029] The "average particle size of abrasive grains" refers to the median value of the volume distribution measured by a particle size distribution analyzer (e.g., a laser diffraction / scattering particle size analyzer) for a sample containing dispersed abrasive grains, and can be measured using a Microtrac MT3300EXII (trade name) manufactured by MicrotracBEL Corp. For example, a sample is prepared by dispersing abrasive grains in water so that the content of abrasive grains is adjusted to a range suitable for measurement, and this sample is then placed in the analyzer to measure the average particle size. When measuring the particle size of abrasive grains in a polishing solution, the content of abrasive grains in the polishing solution is adjusted to a range suitable for measurement, and this sample can be used for measurement in a similar manner. By adjusting the average particle size of the abrasive grains, a high polishing rate and low scratch characteristics of silicon oxide corresponding to the particle size of the abrasive grains can be efficiently obtained.

[0030] From the viewpoint of achieving an excellent balance between the removal rate of silicon oxide on the convex portions of the patterned wafer and the dispersion stability of the abrasive grains, the content of the abrasive grains may be within the following ranges based on the total mass of the polishing liquid: 0.01 mass% or more, 0.05 mass% or more, 0.1 mass% or more, 0.2 mass% or more, 0.3 mass% or more, 0.4 mass% or more, or 0.5 mass% or more; 10 mass% or less, 5 mass% or less, 3 mass% or less, 2.5 mass% or less, 2 mass% or less, 1.8 mass% or less, 1.5 mass% or less, 1.2 mass% or less, 1 mass% or less, 0.8 mass% or less, 0.6 mass% or less, or 0.5 mass% or less. From these viewpoints, the content of the abrasive grains may be 0.01 to 10 mass%, 0.01 to 3 mass%, 0.01 to 1 mass%, 0.05 to 10 mass%, 0.05 to 3 mass%, 0.05 to 1 mass%, 0.1 to 10 mass%, 0.1 to 3 mass%, or 0.1 to 1 mass%.

[0031] (Nitrogen-Containing Aromatic Compound) The polishing liquid according to this embodiment contains a nitrogen-containing aromatic compound (a nitrogen-containing compound having an aromatic ring). The nitrogen-containing aromatic compound may have an aromatic ring containing a nitrogen atom, or may have an aromatic ring not containing a nitrogen atom.

[0032] The nitrogen-containing aromatic compound may have a monocyclic aromatic ring, or a polycyclic aromatic ring (such as a fused ring in which two or more monocyclic aromatic rings are fused, or a fused ring in which one or more monocyclic aromatic rings are fused to one or more monocyclic non-aromatic rings).

[0033] Examples of the monocyclic aromatic ring include a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an imidazole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, and a pyrazine ring.

[0034] Examples of the fused ring formed by condensing two or more monocyclic aromatic rings include a naphthalene ring, an anthracene ring, a benzofuran ring, an isobenzofuran ring, an indole ring, an isoindole ring, a benzothiophene ring, a benzimidazole ring, an indazole ring, a benzoxazole ring, a benzisoxazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, an acridine ring, a quinazoline ring, a cinnoline ring, a phthalazine ring, and a carbazole ring.

[0035] Examples of the fused ring in which one or more monocyclic aromatic rings are fused with one or more monocyclic non-aromatic rings include an indane ring, a fluorene ring, and a tetralin ring.

[0036] The nitrogen-containing aromatic compound may have a heterocycle as the aromatic ring, or may have a heterocycle containing a nitrogen atom, from the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer (e.g., convex portions in an L / S=20 μm / 80 μm region; the same applies below) relative to silicon oxide on a blanket wafer, and from the viewpoint of easily obtaining a high polishing rate of silicon oxide on the convex portions of a patterned wafer. The nitrogen-containing aromatic compound may have a carbon ring (non-heterocycle) as the aromatic ring, or may have a carbon ring (non-heterocycle) not containing a nitrogen atom, from the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer relative to silicon oxide on a blanket wafer, and from the viewpoint of easily obtaining a high polishing rate of silicon oxide on the convex portions of a patterned wafer. From the viewpoint of easily achieving a high removal rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer, and from the viewpoint of easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer, the nitrogen-containing aromatic compound may have at least one ring selected from the group consisting of a monocyclic aromatic ring and a fused ring in which two or more monocyclic aromatic rings are fused, and may have at least one ring selected from the group consisting of a benzene ring (monocyclic aromatic ring), an indole ring, and a quinoline ring.

[0037] The aromatic ring may have a substituent or may not have a substituent (may be unsubstituted). The aromatic ring may have a single substituent or may have multiple substituents. The aromatic ring may have a nitrogen atom-containing substituent, may not have a nitrogen atom-containing substituent, may have a nitrogen atom-free substituent, or may not have a nitrogen atom-free substituent. Examples of the substituent include substituted or unsubstituted alkyl groups, hydroxy groups, carboxy groups, carboxylate groups, aldehyde groups, alkoxy groups, amino groups, amide groups, hydroxyamide groups, nitro groups, cyano groups, mercapto groups, and halogeno groups (fluoro groups, chloro groups, bromo groups, iodo groups, etc.). Examples of the substituent that replaces the hydrogen atom of the alkyl group include hydroxy groups, carboxy groups, carboxylate groups, aldehyde groups, alkoxy groups, amino groups, amide groups, hydroxyamide groups, nitro groups, cyano groups, mercapto groups, and halogeno groups (fluoro groups, chloro groups, bromo groups, iodo groups, etc.).

[0038] From the viewpoint of easily achieving a high removal rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer and easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer, the nitrogen-containing aromatic compound may include a compound having at least one selected from the group consisting of a carboxy group, a carboxylate group, an amino group, and a hydroxyamide group, or may include a compound having at least one selected from the group consisting of a carboxy group, a carboxylate group, an amino group, and a hydroxyamide group as a substituent directly bonded to an aromatic ring. The nitrogen-containing aromatic compound may include a compound not having at least one selected from the group consisting of a carboxy group, a carboxylate group, an amino group, and a hydroxyamide group.

[0039] Examples of the nitrogen-containing aromatic compound include a compound having an amino group, a compound having a hydroxyamide group, an indole compound (a compound having an indole ring), a quinoline compound (a compound having a quinoline ring), and a pyridine compound (a compound having a pyridine ring).

[0040] Examples of compounds having an amino group include aniline, anthranilic acid, etc. From the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer and easily obtaining a high polishing rate of silicon oxide on the convex portions of a patterned wafer, the compound having an amino group may include a compound having an amino group bonded to an aromatic ring (e.g., a monocyclic benzene ring), may include a compound having an amino group and at least one selected from the group consisting of a carboxy group and a carboxylate salt group, or may include a compound having an amino group and at least one selected from the group consisting of a carboxy group and a carboxylate salt group as a functional group bonded to an aromatic ring (e.g., a monocyclic benzene ring).

[0041] Examples of the compound having a hydroxyamide group include benzohydroxamic acid, etc. The compound having a hydroxyamide group may include a compound having a hydroxyamide group bonded to an aromatic ring (e.g., a monocyclic benzene ring), from the viewpoint of easily achieving a high ratio of the removal rate of silicon oxide on the convex portions of a patterned wafer to that of silicon oxide on a blanket wafer, and from the viewpoint of easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer.

[0042] Examples of indole compounds include indole, indole acids (indoleacetic acid, indolepropionic acid, etc.), alkylindoles (methylindole, etc.), phenylindole, hydroxyindole, carboxyindole, alkoxyindole, aminoindole, nitroindole, nitrile indole, and chloroindole.

[0043] Examples of the quinoline compound include quinoline, quinolinol, quinolinecarboxylic acid (such as quinaldic acid), aminoquinoline, and mercaptoquinoline.

[0044] Examples of the pyridine compound include pyridine, hydroxypyridine, aminopyridine, carboxypyridine (picolinic acid, nicotinic acid, isonicotinic acid, etc.), hydroxypyridinecarboxylic acid (hydroxypicolinic acid), aminopyridinecarboxylic acid (aminopicolinic acid), and cyanopyridine.

[0045] From the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer and easily obtaining a high polishing rate of silicon oxide on the convex portions of a patterned wafer, the nitrogen-containing aromatic compound may comprise at least one selected from the group consisting of a compound having an amino group, a compound having a hydroxyamide group, an indole compound, and a quinoline compound, or may comprise at least one selected from the group consisting of a compound having an amino group bonded to an aromatic ring, a compound having a hydroxyamide group bonded to an aromatic ring, an indole compound, and a quinoline compound, or may comprise at least one selected from the group consisting of anthranilic acid, benzohydroxamic acid, indoleacetic acid, and quinaldic acid. That is, the nitrogen-containing aromatic compound may be in an embodiment comprising a compound having an amino group bonded to an aromatic ring, an embodiment comprising anthranilic acid, an embodiment comprising a compound having a hydroxyamide group bonded to an aromatic ring, an embodiment comprising benzohydroxamic acid, an embodiment comprising an indole compound, an embodiment comprising indoleacetic acid, an embodiment comprising a quinoline compound, or an embodiment comprising quinaldic acid. The nitrogen-containing aromatic compound may contain a compound other than a picolinic acid compound, from the viewpoint of easily achieving a high ratio of the removal rate of silicon oxide on the convex portions of a patterned wafer to that of silicon oxide on a blanket wafer, and from the viewpoint of easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer.

[0046] As the content of the nitrogen-containing aromatic compound, the content of the compound having an amino group bonded to an aromatic ring, the content of anthranilic acid, the content of the compound having a hydroxyamide group bonded to an aromatic ring, the content of benzohydroxamic acid, the content of an indole compound, the content of indoleacetic acid, the content of a quinoline compound, or the content of quinaldic acid, the content A may be in the following range based on the total mass of the polishing liquid. From the viewpoints of easily achieving a high polishing rate ratio of silicon oxide in the convex portions of the patterned wafer to silicon oxide in the blanket wafer, easily obtaining a high polishing rate of silicon oxide in the convex portions of the patterned wafer, and easily suppressing the polishing rate of silicon nitride, the content A may be 0.0001% by mass or more, 0.0005% by mass or more, 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, 0.008% by mass or more, 0.01% by mass or more, 0.015% by mass or more, 0.02% by mass or more, 0.025% by mass or more, 0.03% by mass or more, 0.035% by mass or more, 0.04% by mass or more, 0.045% by mass or more, or 0.05% by mass or more. The content A is set to 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.8% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, from the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of the patterned wafer to silicon oxide on the blanket wafer, easily obtaining a high polishing rate of silicon oxide on the convex portions of the patterned wafer, easily suppressing the polishing rate of silicon nitride, and easily achieving excellent dispersion stability of the abrasive grains. Mass% or less, 0.2 mass% or less, 0.1 mass% or less, 0.09 mass% or less, 0.08 mass% or less, 0.07 mass% or less, 0.06 mass% or less, 0.05 mass% or less, 0.045 mass% or less, 0.04 mass% or less, 0.03 It may be 5% by mass or less, 0.03% by mass or less, 0.025% by mass or less, 0.02% by mass or less, 0.015% by mass or less, 0.01% by mass or less, less than 0.01% by mass, 0.008% by mass or less, or 0.005% by mass or less.From these viewpoints, the content A may be 0.0001 to 5 mass%, 0.0001 to 1 mass%, 0.0001 to 0.1 mass%, 0.0001 to 0.015 mass%, 0.0001 to 0.008 mass%, 0.001 to 5 mass%, 0.001 to 1 mass%, 0.001 to 0.1 mass%, 0.001 to 0.015 mass%, 0.001 to 0.008 mass%, 0.008 to 5 mass%, 0.008 to 1 mass%, 0.008 to 0.1 mass%, 0.008 to 0.015 mass%, 0.015 to 5 mass%, 0.015 to 1 mass%, or 0.015 to 0.1 mass%. The content of nitrogen-containing aromatic compounds is the total amount of compounds that fall under nitrogen-containing aromatic compounds, and the content of compounds having an amino group bonded to an aromatic ring is the total amount of compounds that fall under compounds having an amino group bonded to an aromatic ring, and the same applies to other similar expressions, including the following expressions.

[0047] The mass ratio B may be in the following ranges as the mass ratio of the nitrogen-containing aromatic compound to the abrasive grains (nitrogen-containing aromatic compound / abrasive grains), the mass ratio of the compound having an amino group bonded to an aromatic ring to the abrasive grains (compound having an amino group bonded to an aromatic ring / abrasive grains), the mass ratio of the anthranilic acid to the abrasive grains (anthranilic acid / abrasive grains), the mass ratio of the compound having a hydroxyamide group bonded to an aromatic ring to the abrasive grains (compound having a hydroxyamide group bonded to an aromatic ring / abrasive grains), the mass ratio of the benzohydroxamic acid to the abrasive grains (benzohydroxamic acid / abrasive grains), the mass ratio of the indole compound to the abrasive grains (indole compound / abrasive grains), the mass ratio of the indoleacetic acid to the abrasive grains (indoleacetic acid / abrasive grains), the mass ratio of the quinoline compound to the abrasive grains (quinoline compound / abrasive grains), or the mass ratio of the quinaldic acid to the abrasive grains (quinaldic acid / abrasive grains). From the viewpoint of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of the patterned wafer to silicon oxide on the blanket wafer, easily obtaining a high polishing rate of silicon oxide on the convex portions of the patterned wafer, and easily suppressing the polishing rate of silicon nitride, the mass ratio B may be 0.001 or more, 0.002 or more, 0.003 or more, 0.005 or more, 0.008 or more, 0.01 or more, 0.015 or more, 0.02 or more, 0.025 or more, 0.03 or more, 0.035 or more, 0.04 or more, 0.05 or more, 0.08 or more, or 0.1 or more. The mass ratio B may be 1 or less, less than 1, 0.8 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, 0.08 or less, 0.05 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, 0.02 or less, 0.015 or less, or 0.01 or less, from the viewpoints of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of the patterned wafer relative to silicon oxide on the blanket wafer, easily obtaining a high polishing rate of silicon oxide on the convex portions of the patterned wafer, easily suppressing the polishing rate of silicon nitride, and easily achieving excellent dispersion stability of the abrasive grains.From these viewpoints, the mass ratio B may be 0.001 to 1, 0.001 to 0.3, 0.001 to 0.1, 0.001 to 0.05, 0.001 to 0.03, 0.001 to 0.015, 0.005 to 1, 0.005 to 0.3, 0.005 to 0.1, 0.005 to 0.05, 0.005 to 0.03, 0.005 to 0.015, 0.015 to 1, 0.015 to 0.3, 0.015 to 0.1, 0.015 to 0.05, 0.015 to 0.03, 0.03 to 1, 0.03 to 0.3, 0.03 to 0.1, or 0.03 to 0.05.

[0048] (Other Additives) The polishing liquid according to this embodiment may further contain other additives (components other than those described above) according to desired properties. Examples of such additives include nonionic polymers, cationic compounds, pH adjusters (described later), polar solvents such as ethanol and acetone, and cyclic monocarboxylic acids.

[0049] The polishing liquid according to this embodiment may contain a compound a having a molecular weight of 100,000 or less and four or more hydroxy groups, or may not contain compound a. The content of compound a may be 0.01 mass% or less, less than 0.01 mass%, 0.001 mass% or less, 0.0001 mass% or less, or substantially 0 mass% based on the total mass of the polishing liquid. The polishing liquid according to this embodiment may contain a compound b having four or more amino groups, or may not contain compound b. The content of compound b may be 0.001 mass% or less, less than 0.001 mass%, 0.0001 mass% or less, 0.00001 mass% or less, or substantially 0 mass% based on the total mass of the polishing liquid. The mass ratio of the content of compound a to the content of compound b (compound a / compound b) may be 0.10 or less, or less than 0.10.

[0050] (Water) The water is not particularly limited, but may include at least one selected from the group consisting of deionized water, ion-exchanged water, and ultrapure water.

[0051] (pH) The pH of the polishing liquid according to this embodiment may be in the following ranges: from the viewpoint of easily achieving a high removal rate ratio of silicon oxide on the convex portions of a patterned wafer to silicon oxide on a blanket wafer, from the viewpoint of easily obtaining a high removal rate of silicon oxide on the convex portions of a patterned wafer, and from the viewpoint of easily suppressing the removal rate of silicon nitride, the pH may be 12.0 or less, 11.0 or less, 10.5 or less, less than 10.5, 10.0 or less, less than 10.0, 9.5 or less, 9.0 or less, less than 9.0, 8.8 or more. or less, 8.5 or less, 8.2 or less, 8.1 or less, 8.0 or less, less than 8.0, 7.8 or less, 7.6 or less, 7.5 or less, 7.2 or less, 7.0 or less, less than 7.0, 6.9 or less, 6.8 or less, 6.7 or less, 6.5 or less, 6.3 or less, 6.2 or less, 6.1 or less, 6.0 or less, less than 6.0, 5.9 or less, 5.7 or less, 5.5 or less, less than 5.5, 5.4 or less, 5.3 or less, 5.2 or less, 5.0 or less, less than 5.0, or 4.9 or less. From the viewpoints of easily achieving a high polishing rate ratio of silicon oxide on the convex portions of the patterned wafer to silicon oxide on the blanket wafer, easily obtaining a high polishing rate of silicon oxide on the convex portions of the patterned wafer, easily suppressing the polishing rate of silicon nitride, and easily achieving excellent dispersion stability of the abrasive grains, the pH may be 4.0 or more, 4.5 or more, 4.9 or more, 5.0 or more, more than 5.0, 5.2 or more, 5.3 or more, 5.4 or more, 5.5 or more, more than 5.5, 5.7 or more, 5.9 or more, 6.0 or more, more than 6.0, 6.1 or more, 6.2 or more, 6.3 or more, 6.5 or more, 6.7 or more, 6.8 or more, 6.9 or more, 7.0 or more, more than 7.0, 7.2 or more, 7.5 or more, 7.6 or more, 7.8 or more, 8.0 or more, or more than 8.0, or 8.1 or more. From these viewpoints, the pH may be 4.0 to 12.0, 4.0 to 9.0, 4.0 to 8.0, 4.0 to 7.0, 4.0 to 6.0, 5.0 to 12.0, 5.0 to 9.0, 5.0 to 8.0, 5.0 to 7.0, 5.0 to 6.0, 6.0 to 12.0, 6.0 to 9.0, 6.0 to 8.0, 6.0 to 7.0, 7.0 to 12.0, 7.0 to 9.0, 7.0 to 8.0, 8.0 to 12.0, or 8.0 to 9.0. The pH can be measured by the method described in the Examples.With regard to the lower limit of the pH, it is presumed that by keeping the pH in the above-mentioned range, the zeta potential of the abrasive grains is likely to be maintained negative within a range in which the electrostatic repulsion between the abrasive grains and the surface to be polished does not become excessively strong, and the electrostatic repulsion between the abrasive grains is likely to be maintained in a suitable state, making it easier to achieve excellent dispersion stability of the abrasive grains. However, the factors are not limited to these.

[0052] Since the pH may vary depending on the type of compound used as an additive, a pH adjuster may be used to adjust the pH to the above range. The pH adjuster is not particularly limited, and examples thereof include acids such as nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and boric acid; and bases such as sodium hydroxide, ammonia (e.g., aqueous ammonia), potassium hydroxide, and calcium hydroxide. Nitrogen-containing aromatic compounds and other additives may also be used to adjust the pH. From the viewpoint of improving productivity, the polishing liquid may be prepared without using a pH adjuster, and this polishing liquid may be directly applied to CMP.

[0053] <Method of preparing and using the polishing liquid> The polishing liquid according to this embodiment can be classified into (a) a normal type, (b) a concentrated type, and (c) a multi-liquid type (for example, a two-liquid type, such as a polishing liquid set for CMP), and the preparation method and usage method differ depending on the type. The (a) normal type is a polishing liquid that can be used as is during polishing without pretreatment such as dilution. The (b) concentrated type is a polishing liquid in which the components are concentrated compared to the (a) normal type, taking into consideration convenience in storage or transportation. The (c) multi-liquid type is a polishing liquid in which the components are separated into multiple liquids (for example, a first liquid containing certain components and a second liquid containing other components) during storage or transportation, and these liquids are mixed when used.

[0054] (a) The normal type can be obtained by dissolving or dispersing abrasive grains and additives in water, which is the main dispersion medium. The polishing liquid can be prepared using, for example, a stirrer, homogenizer, ultrasonic disperser, wet ball mill, etc. Note that a process of micronizing the abrasive grains may be performed during the preparation process of the polishing liquid so that the average particle size of the abrasive grains falls within the desired range. The micronization process of the abrasive grains can be performed by a sedimentation classification method or a method using a high-pressure homogenizer. The sedimentation classification method is a method that includes a step of forcibly sedimenting a slurry containing abrasive grains using a centrifuge and a step of extracting only the supernatant liquid. On the other hand, the method using a high-pressure homogenizer is a method in which abrasive grains in a dispersion medium are collided with each other at high pressure.

[0055] The (b) concentrated type is diluted with water immediately before use to achieve the desired component content. After dilution, stirring may be carried out for any length of time until the liquid properties (pH, abrasive grain size, etc.) and polishing properties (silicon oxide polishing rate, polishing selectivity between silicon oxide and silicon nitride, etc.) are comparable to those of the (a) regular type. Since the volume of such a (b) concentrated type decreases depending on the degree of concentration, storage and transportation costs can be reduced.

[0056] The concentration ratio may be 1.5 times or more, 2 times or more, 3 times or more, or 5 times or more. A concentration ratio of 1.5 times or more tends to provide advantages in terms of storage and transportation compared to a concentration ratio of less than 1.5 times. The concentration ratio may be 40 times or less, 20 times or less, or 15 times or less. A concentration ratio of 40 times or less tends to suppress agglomeration of abrasive grains more easily compared to a concentration ratio of more than 40 times.

[0057] The (c) multiple-liquid type has the advantage over the (b) concentrated type that by appropriately separating each liquid (first liquid, second liquid, etc.), it is possible to avoid abrasive aggregation, etc. Here, the components contained in each liquid are arbitrary. The (c) multiple-liquid type (CMP polishing liquid set) is a polishing liquid set for obtaining a polishing liquid by mixing a first liquid (slurry) and a second liquid (additive liquid). In the (c) multiple-liquid type, the components of the CMP polishing liquid are stored separately as a first liquid and a second liquid, the first liquid containing abrasive grains and water, and the second liquid containing a nitrogen-containing aromatic compound and water. The first liquid and the second liquid may contain other components blended as needed. In this case, to improve the dispersibility of abrasive grains in the first liquid, an optional acid or alkali may be blended into the first liquid to adjust the pH.

[0058] (c) A multi-liquid type polishing liquid is useful when the combination of components tends to deteriorate the polishing properties in a relatively short time when mixed due to aggregation of abrasive grains, etc. From the viewpoint of reducing storage and transportation costs, at least one of the liquids (first liquid, second liquid, etc.) may be concentrated. In this case, when using the polishing liquid, each liquid and water can be mixed. The concentration ratio and pH of each liquid are arbitrary, as long as the final mixture has liquid properties and polishing properties comparable to those of the (a) normal type polishing liquid.

[0059] <Polishing Method> The polishing method according to this embodiment includes a polishing step of polishing a surface to be polished using the polishing liquid according to this embodiment. The polishing liquid used in the polishing step may be a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set described above. That is, the polishing method according to this embodiment may include a polishing step of polishing a surface to be polished using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set described above.

[0060] The polishing method according to this embodiment uses a polishing liquid in which the content of each component, pH, etc., are adjusted, and can planarize a substrate having a silicon oxide film on its surface using CMP technology. The polishing method according to this embodiment is suitable for polishing that requires high speed, high flatness, and low polishing scratches, such as polishing of ILD films, and is suitable for applications in which a large number of ILD films must be polished in a short period of time. According to one aspect of the polishing method according to this embodiment, the effects of improving the removal rate of silicon oxide on blanket wafers and improving in-plane uniformity can be efficiently obtained. According to one aspect of the polishing method according to this embodiment, the use of the polishing liquid according to this embodiment achieves excellent dispersion stability of abrasive grains, achieves a sufficiently high removal rate, and reduces the occurrence of polishing scratches.

[0061] The polishing step may be a step of supplying the polishing liquid according to this embodiment between a substrate and a polishing member (a polishing member, such as a polishing pad), and polishing the substrate with the polishing member. The polishing method according to this embodiment is suitable for polishing a substrate having a silicon oxide film on its surface. Therefore, the surface to be polished may contain silicon oxide, and the polishing step may be a step of supplying the polishing liquid according to this embodiment between the silicon oxide film on the substrate having the silicon oxide film on its surface and the polishing member, and polishing the silicon oxide film with the polishing member.

[0062] The polishing method according to this embodiment may be such that the surface to be polished has a concave-convex pattern composed of convex portions (line portions) and concave portions (space portions), and the convex portions contain silicon oxide. The width of the convex portions in the concave-convex pattern may be 30 μm or less, or 20 μm or less. The width of the convex portions in the concave-convex pattern may be 10 μm or more, or 20 μm or more. The sum of the width of the convex portions and the width of the concave portions in the concave-convex pattern may be 200 μm or less, or 100 μm or less. The sum of the width of the convex portions and the width of the concave portions in the concave-convex pattern may be 80 μm or more, or 100 μm or more.

[0063] The polishing method according to this embodiment is suitable for polishing a substrate having a silicon oxide film on its surface in the manufacturing process of a device. Examples of the device include discrete semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, and thyristors; memory elements such as DRAM (dynamic random access memory), SRAM (static random access memory), EPROM (erasable programmable read-only memory), mask ROM (mask read-only memory), EEPROM (electrically erasable programmable read-only memory), and flash memory; logic circuit elements such as microprocessors, DSPs, and ASICs; integrated circuit elements such as compound semiconductors, typified by MMICs (monolithic microwave integrated circuits); hybrid integrated circuits (hybrid ICs); light-emitting diodes; and photoelectric conversion elements such as charge-coupled devices.

[0064] According to one aspect of the polishing liquid of this embodiment, a high polishing rate can be achieved without being largely dependent on the uneven shape of the polished surface. Therefore, a polishing method using this polishing liquid can be applied to substrates for which it has been difficult to achieve a high polishing rate using conventional polishing liquids.

[0065] The polishing method according to this embodiment is suitable for planarizing a polished surface having steps (unevenness) on the surface. Examples of substrates having such a polished surface include semiconductor devices for logic circuits. Furthermore, the polishing method according to this embodiment is suitable for polishing surfaces including T-shaped or lattice-shaped concave or convex portions when viewed from above. For example, the polishing method according to this embodiment can also polish silicon oxide films formed on the surfaces of semiconductor devices (DRAMs, flash memories, etc.) having memory cells at high speeds. These are areas where high polishing rates have been difficult to achieve using conventional CMP polishing liquids. This demonstrates that one aspect of the polishing liquid according to this embodiment can achieve high polishing rates without being significantly dependent on the unevenness of the polished surface.

[0066] The substrate is not limited to a substrate having only a silicon oxide film on its surface, but may also be a substrate having, on its surface, in addition to a silicon oxide film, a silicon nitride film, a polycrystalline silicon film, etc. The substrate may also be a substrate having, on a wiring board having predetermined wiring, an inorganic insulating film such as silicon oxide, glass, or silicon nitride; or a film mainly containing polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN, etc.

[0067] As an example of a process including the polishing method according to this embodiment, a process for forming an ILD (interlayer dielectric) film structure by CMP will be described below. Figure 1 is a schematic cross-sectional view showing the process of polishing an ILD film, illustrating the process of forming an ILD film between wirings. Figure 1(a) is a schematic cross-sectional view showing a substrate before polishing. Figure 1(b) is a schematic cross-sectional view showing the substrate after polishing.

[0068] 1( a), in a substrate 100 before polishing, a wiring 20 is formed on a lower substrate (not shown) having a predetermined lower wiring (not shown) via an ILD film 10, and a silicon oxide film 30 is formed to cover the wiring 20. Because the silicon oxide film 30 is formed on the ILD film 10 on which the wiring 20 is formed, the portion above the wiring 20 is higher than the other portions, resulting in a step D on the surface of the silicon oxide film 30. The wiring 20 is connected to the lower wiring, etc., by a contact plug 40 formed to penetrate the ILD film 10.

[0069] In the process of forming the ILD film structure, in order to eliminate the step D, protruding unnecessary portions on the surface of the silicon oxide film 30 are preferentially removed by CMP. To polish the silicon oxide film 30, the substrate 100 is placed on a polishing member so that the surface of the silicon oxide film 30 abuts against the polishing member, and the surface of the silicon oxide film 30 is polished with the polishing member. More specifically, the surface to be polished (front surface) of the silicon oxide film 30 is pressed against the polishing member of a polishing table, and the surface to be polished and the polishing member are moved relative to each other while a polishing liquid is supplied between them, thereby polishing the silicon oxide film 30. This eliminates the step D, and ultimately, as shown in FIG. 1( b), the height of the wiring 20 portion and the height of the other portions on the surface of the silicon oxide film 30 become approximately the same, resulting in a substrate 100a having a silicon oxide film 30 (ILD film) with a flat surface.

[0070] The polishing apparatus used for polishing may be, for example, an apparatus equipped with a holder for holding the substrate, a polishing platen to which a polishing pad is attached, and a means for supplying a polishing liquid onto the polishing pad. Examples of the polishing apparatus include polishing apparatuses manufactured by Ebara Corporation (model numbers: EPO-111, EPO-222, F-REX200, and F-REX300), and polishing apparatuses manufactured by Applied Materials (product names: Mirra 3400 and Reflexion). The material constituting the polishing pad is not particularly limited, and examples include general nonwoven fabric, polyurethane foam, and porous fluororesin. Furthermore, the polishing pad may be grooved to allow the polishing liquid to accumulate.

[0071] There are no particular restrictions on the polishing conditions, but in order to prevent the substrate from protruding, the rotation speed of the polishing platen is set to 200 min －１ The pressure (processing load) applied to the substrate may be 100 kPa or less, from the viewpoint of easily suppressing polishing scratches on the surface to be polished. During polishing, a polishing liquid may be continuously supplied to the polishing pad by a pump or the like. There is no limit to the amount of supply, but the surface of the polishing pad may be constantly covered with the polishing liquid. After polishing is completed, the substrate may be thoroughly washed in running water, and then water droplets adhering to the substrate may be removed using a spin dryer or the like, followed by drying.

[0072] By polishing in this manner, surface irregularities can be eliminated, and a smooth surface can be obtained over the entire surface of the substrate. Furthermore, by repeating the steps of forming a film and polishing this film a predetermined number of times, a structure having a desired number of layers can be manufactured.

[0073] The substrate (structure) thus obtained can be used as various electronic components. Specific examples of electronic components include semiconductor elements; optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits, optical switching elements, and optical waveguides made of glass and crystalline materials; end faces of optical fibers; optical single crystals such as scintillators; solid-state laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as SiC, GaP, and GaAs; glass substrates for magnetic disks; and magnetic heads.

[0074] <Manufacturing Method, etc.> The component manufacturing method according to this embodiment includes a component fabrication step in which a component is obtained using a substrate (a member to be polished) polished by the polishing method according to this embodiment. The component according to this embodiment is a component obtained by the component manufacturing method according to this embodiment. The component according to this embodiment is not particularly limited, and may be an electronic component (e.g., a semiconductor component such as a semiconductor package), a wafer (e.g., a semiconductor wafer), or a chip (e.g., a semiconductor chip). As one aspect of the component manufacturing method according to this embodiment, an electronic component is obtained using a substrate polished by the polishing method according to this embodiment. As one aspect of the component manufacturing method according to this embodiment, a semiconductor component (e.g., a semiconductor package) is obtained using a substrate polished by the polishing method according to this embodiment. The component manufacturing method according to this embodiment may include a polishing step in which a substrate is polished by the polishing method according to this embodiment before the component fabrication step.

[0075] The component manufacturing method according to this embodiment may include, as one aspect of the component manufacturing process, a singulation process for singulating a substrate (a polished member) polished by the polishing method according to this embodiment. The singulation process may be, for example, a process for dicing a wafer (e.g., a semiconductor wafer) polished by the polishing method according to this embodiment to obtain chips (e.g., semiconductor chips). As one aspect of the component manufacturing method according to this embodiment, the electronic component manufacturing method according to this embodiment may include a process for singulating a substrate polished by the polishing method according to this embodiment to obtain electronic components (e.g., semiconductor components). As one aspect of the component manufacturing method according to this embodiment, the semiconductor component manufacturing method according to this embodiment may include a process for singulating a substrate polished by the polishing method according to this embodiment to obtain semiconductor components (e.g., semiconductor packages).

[0076] The component manufacturing method according to this embodiment may include, as one aspect of the component manufacturing process, a connection process in which a substrate (a polished member) polished by the polishing method according to this embodiment is connected (e.g., electrically connected) to another connected object. The connected object to be connected to the substrate polished by the polishing method according to this embodiment is not particularly limited and may be the substrate polished by the polishing method according to this embodiment, or may be a connected object different from the substrate polished by the polishing method according to this embodiment. In the connection process, the substrate and the connected object may be directly connected (connected in a state where the substrate and the connected object are in contact with each other), or the substrate and the connected object may be connected via another member (such as a conductive member). The connection process may be performed before the singulation process, after the singulation process, or before or after the singulation process.

[0077] The connecting step may be a step of connecting a polished surface of a base polished by the polishing method according to this embodiment to a connected body, or a step of connecting a connecting surface of a base polished by the polishing method according to this embodiment to a connecting surface of a connected body. The connecting surface of the base may be a polished surface polished by the polishing method according to this embodiment. A connecting body including a base and a connected body can be obtained by the connecting step. In the connecting step, if the connecting surface of the base has a metal portion, the connected body may be brought into contact with the metal portion. In the connecting step, if the connecting surface of the base has a metal portion and the connecting surface of the connected body has a metal portion, the metal portions may be brought into contact with each other. The metal portion may contain copper.

[0078] The device according to this embodiment (for example, an electronic device such as a semiconductor device) includes a substrate polished by the polishing method according to this embodiment and at least one selected from the group consisting of the part according to this embodiment.

[0079] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0080] <Preparation of Cerium Oxide Powder> 40 kg of cerium carbonate hydrate was divided and placed in 10 alumina containers, and each was calcined in air at 830°C for 2 hours to obtain a total of 20 kg of yellow-white powder. Phase identification of this powder was performed using X-ray diffraction, and it was confirmed that the powder contained polycrystalline cerium oxide. The particle size of the powder obtained by calcination was observed using an SEM and was found to be in the range of 20 to 100 μm. Next, 20 kg of the cerium oxide powder was dry-pulverized using a jet mill to obtain cerium oxide powder. The specific surface area of ​​the cerium oxide powder after pulverization was 9.4 m ２ The specific surface area was measured by the BET method.

[0081] <Slurry Preparation> 15.0 kg of the cerium oxide powder obtained above and 84.85 kg of deionized water were placed in a container and mixed. Next, 0.375 kg of an aqueous solution of ammonium polyacrylate (concentration: 40% by mass, molecular weight: approximately 10,000) was added as a dispersant, and the mixture was stirred for 10 minutes to obtain a cerium oxide mixed solution. This cerium oxide mixed solution was transferred to another container over 30 minutes. During this time, the cerium oxide mixed solution was irradiated with ultrasonic waves at an ultrasonic frequency of 400 kHz within the pipe through which the solution was transferred.

[0082] The cerium oxide mixture described above, which had been delivered after ultrasonic irradiation, was placed in four 500 mL polyethylene containers, each containing 500 g ± 5 g. The cerium oxide mixture in each container was centrifuged for 2 minutes at a centrifugal force of 500 G applied to the periphery. After centrifugation, the supernatant fractions were collected from the containers. The supernatant fractions collected from the four containers were mixed together to obtain a slurry. The slurry contained approximately 6.0 mass% of cerium oxide particles based on the total mass of the slurry.

[0083] The slurry was diluted with pure water to obtain a sample for particle size measurement, and the average particle size of the abrasive grains was measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII, manufactured by MicrotracBEL Corp.). The average particle size of the abrasive grains was found to be 140 nm.

[0084] <Preparation of Polishing Slurry for CMP> (Examples 1 to 11) The above-mentioned slurry, each additive, and deionized water were mixed according to the following procedure to obtain a polishing slurry (balance: deionized water) containing 0.50 mass % of abrasive grains, additives (indoleacetic acid, benzohydroxamic acid, quinaldic acid, or anthranilic acid) in the amounts shown in Table 1 below, and 0.005 mass % of dispersant (ammonium polyacrylate mixed during the preparation of the above-mentioned slurry).

[0085] Specifically, an additive solution was prepared by dissolving each additive in deionized water. Equal amounts of the slurry and the additive solution were then mixed and stirred for 10 minutes to obtain a concentrated stock solution for polishing liquid containing 5.00% by mass of abrasive grains based on the total mass. The stock solution for polishing liquid contained 10 times the amount of abrasive grains and additives relative to the 0.50% by mass abrasive grain content of the final polishing liquid.

[0086] The polishing liquid was obtained by diluting the stock solution for the polishing liquid 10 times with deionized water. The average particle size of the abrasive grains in the polishing liquid of each example, measured by the same method as that for the average particle size of the abrasive grains in the above-mentioned slurry, was equal to that of the above-mentioned slurry.

[0087] Comparative Example 1 The same procedure as in Example was carried out except that no additive was used, to obtain a polishing liquid (balance: deionized water) containing 0.50 mass % of abrasive grains and 0.005 mass % of a dispersant (ammonium polyacrylate mixed during the preparation of the above-mentioned slurry).

[0088] <Zeta Potential Measurement> An appropriate amount of polishing liquid was placed in a "Delsa Nano C" polishing container manufactured by Beckman Coulter, Inc., and measurements were performed twice at 25°C. The average value of the displayed zeta potentials was taken as the zeta potential. In each of the Examples and Comparative Examples, the zeta potential of the abrasive grains was negative, as shown in Table 1.

[0089] <pH Measurement> The pH of the polishing solution was measured under the following conditions. The results are shown in Table 1. Measurement temperature: 25°C Measuring device: HORIBA, Ltd., product name: Model (D-71) Measurement method: After three-point calibration of the pH meter using a phthalate pH standard solution (pH: 4.01), a neutral phosphate pH standard solution (pH: 6.86), and a borate pH standard solution (pH: 9.18) as pH standard solutions, the pH meter electrode was immersed in the polishing solution, and the pH was measured using the measuring device after 2 minutes or more had passed and the pH had stabilized.

[0090] <Evaluation of dispersion stability of abrasive grains> The above-mentioned polishing liquid immediately after preparation was left to stand for one week (168 hours), and the average particle size of the abrasive grains one week after preparation was measured using the same method as for the average particle size of the abrasive grains in the above-mentioned slurry. The rate of change in the average particle size of the abrasive grains after one week was calculated as "[(average particle size in the polishing liquid after one week - average particle size of the abrasive grains in the above-mentioned slurry) / average particle size of the abrasive grains in the above-mentioned slurry] x 100". A rate of change in the average particle size of the abrasive grains of 4% or less after one week was evaluated as "A", and a rate of change in the average particle size of the abrasive grains of more than 4% after one week was evaluated as "B". The results are shown in Table 1.

[0091] <Evaluation of Polishing Characteristics> (Preparation of Evaluation Wafer) A blanket wafer (BKW) was prepared by coating a silicon oxide film (SiO ２ A φ200 mm unpatterned wafer having a silicon nitride film (SiN, initial film thickness: 1000 nm) on its surface and a φ200 mm unpatterned wafer having a silicon nitride film (SiN, initial film thickness: 200 nm) on its surface were prepared.

[0092] A test pattern wafer (PTW) (model number: Sematech 864, manufactured by Advantec Co., Ltd., φ200 mm) was prepared as a pattern wafer (PTW). The protruding portions (line portions) had an initial step height 500 nm higher than the recessed portions (space portions). The protruding portions were provided with a silicon nitride film (initial film thickness: 140 nm) as a stopper for the silicon oxide film, assuming evaluation for shallow trench isolation. The pattern wafer had multiple 20 mm x 20 mm die units, and each die unit had multiple 4 mm x 4 mm unit areas. The pattern wafer has a 4 mm x 4 mm unit area and an area having a parallel line pattern with a pitch of 100 μm width and a Line / Space (L / S) of 10 μm / 90 μm (protrusion density: 10%) to 90 μm / 10 μm (protrusion density: 90%) in 10 μm increments.

[0093] (Polishing Procedure) The above-mentioned evaluation wafer was polished using a polishing machine (Applied Materials, product name: Mirra 3400). The above-mentioned evaluation wafer was set on a holder having an adsorption pad for attaching the substrate. A polishing pad made of porous urethane resin (K-groove groove, DuPont (Dow), model number: IC-1010) was attached to a polishing platen with a diameter of 500 mm.

[0094] The holder was placed on the polishing pad with the polished surface of the evaluation wafer facing downwards, and the inner tube pressure, retainer ring pressure, and membrane pressure were set to 14 kPa, 21 kPa, and 14 kPa, respectively.

[0095] Then, the polishing pad and the evaluation wafer were each polished for 93 minutes while the polishing liquid was dropped onto the polishing pad at a flow rate of 200 mL / min. －１ and 87 min －１ The polished surface was polished by rotating the wafer at a speed of 1000 rpm. For blanket wafers, polishing was performed for 30 seconds. For patterned wafers, the polishing time was set within the range of 20 to 60 seconds, depending on the polishing rate evaluated for the blanket wafer, and the time required for the silicon nitride film underlying the silicon oxide film to not be exposed in the convex portions in the L / S = 20 μm / 80 μm region was set, and polishing was performed for that polishing time. Next, the evaluation wafer after polishing was thoroughly washed with pure water using a PVA brush (polyvinyl alcohol brush) and then dried.

[0096] (Evaluation of Polishing Rate) Using an optical interference film thickness measuring device (trade name: AFT-5100, manufactured by Nanometrics Japan Co., Ltd.), the change in film thickness of the film to be polished before and after polishing was measured as follows to obtain the polishing rate. In addition, the polishing rate ratio (PTW / BKW) of silicon oxide on the convex portions of the patterned wafer to silicon oxide on the blanket wafer was calculated. The results are shown in Table 1.

[0097] For blanket wafers, the change in film thickness was measured at a total of 41 measurement points (20 points on both sides of the center point), including the center point and points spaced 5 mm apart in the diameter direction from the center point (the next measurement point after the measurement point 95 mm from the center was 97 mm from the center). The change in film thickness was measured at these 41 points over a 30-second polishing time, and the average value was calculated as the polishing rate for the blanket wafer.

[0098] For the patterned wafer, the amount of change in film thickness at the convex portions in the region of L / S = 20 μm / 80 μm was measured to obtain the polishing rate of the patterned wafer. In the central die unit (20 mm × 20 mm) of the patterned wafer, the amount of change in film thickness was measured at one location in the center of one unit area (4 mm × 4 mm) of L / S = 20 μm / 80 μm.

[0099]

[0100] 10 ILD film, 20 wiring, 30 silicon oxide film, 40 contact plug, 100, 100a substrate, D step.

Claims

1. A polishing liquid for CMP comprising an abrasive, a nitrogen-containing compound having an aromatic ring, and water, wherein the abrasive comprises cerium-based particles, and the abrasive has a negative zeta potential.

2. The CMP polishing liquid of claim 1, wherein the cerium-based particles include cerium oxide.

3. The CMP polishing liquid according to claim 1, wherein the nitrogen-containing compound includes a compound having an amino group bonded to an aromatic ring.

4. The CMP polishing liquid according to claim 3, wherein the nitrogen-containing compound comprises anthranilic acid.

5. The CMP polishing liquid according to claim 1, wherein the nitrogen-containing compound includes a compound having a hydroxyamide group bonded to an aromatic ring.

6. The CMP polishing liquid according to claim 5, wherein the nitrogen-containing compound comprises benzohydroxamic acid.

7. The CMP polishing liquid according to claim 1, wherein the nitrogen-containing compound comprises an indole compound.

8. The CMP polishing liquid according to claim 7, wherein the nitrogen-containing compound comprises indole acetic acid.

9. The CMP polishing liquid according to claim 1, wherein the nitrogen-containing compound comprises a quinoline compound.

10. The CMP polishing liquid according to claim 9, wherein the nitrogen-containing compound comprises quinaldic acid.

11. The polishing liquid for CMP according to claim 1, wherein the content of the nitrogen-containing compound is 0.001 to 5 mass %.

12. The polishing liquid for CMP according to claim 1, having a pH of 4.0 to 9.

0.

13. A polishing liquid set for CMP, in which the components of the polishing liquid for CMP according to any one of claims 1 to 12 are stored separately as a first liquid and a second liquid, the first liquid containing the abrasive grains and water, and the second liquid containing the nitrogen-containing compound and water.

14. A polishing method comprising a step of polishing a surface to be polished with the polishing liquid for CMP according to any one of claims 1 to 12.

15. The polishing method according to claim 14, wherein the surface to be polished comprises silicon oxide.