TW202446900A - Composition for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

The invention provides a composition for chemical mechanical polishing and a chemical mechanical polishing method. A surface to be polished, where conductive metals such as tungsten or cobalt coexist with insulating films such as silicon oxide films, can be polished at a high speed and evenly, and generations of surface defects after polishing can be reduced. The composition for chemical mechanical polishing of the invention contains silica particles and a liquid medium. The ratio of the long diameter (Rmax) to the short diameter (Rmin) of the silica particles (Rmax/Rmin) is 2.5 or more, and the zeta potential of the silica particles in the composition for chemical mechanical polishing exceeds 0 mV.

Description

Composition for chemical mechanical polishing and chemical mechanical polishing method

The present invention relates to a chemical mechanical polishing composition and a chemical mechanical polishing method.

The miniaturization of wiring layers including wiring and plugs formed in semiconductor devices is progressing. In response to this, a method of flattening the wiring layer by chemical mechanical polishing (hereinafter also referred to as "CMP") is used. The ultimate goal of this CMP is to flatten the polished surface after polishing to obtain a defect-free and corrosion-free surface. Therefore, the chemical mechanical polishing composition used in CMP is evaluated based on characteristics such as material removal rate, surface defect rate after polishing, and metal corrosion prevention after polishing.

In recent years, tungsten (W) or cobalt (Co) has begun to be used as a conductive metal due to the further miniaturization of wiring layers. Therefore, it is required to efficiently remove the remaining tungsten or cobalt by CMP and suppress the corrosion of tungsten or cobalt to form a good surface state. Regarding the chemical mechanical polishing of such tungsten or cobalt, chemical mechanical polishing compositions containing various additives have been proposed (for example, refer to Patent Documents 1 and 2). [Prior Art Documents] [Patent Documents]

[Patent document 1] Japanese Patent Publication No. 2017-514295 [Patent document 2] Japanese Patent Publication No. 2016-030831

[The problem that the invention wants to solve]

With the popularization of semiconductor wafers containing conductive metals such as tungsten or cobalt, there is a need for a chemical mechanical polishing composition and a chemical mechanical polishing method that can polish a polishing surface where a conductive metal such as tungsten or cobalt and an insulating film such as a silicon oxide film coexist at a high speed and flatly, and can reduce the occurrence of surface defects after polishing.

In particular, when the polishing speed of the conductive metal is faster than the polishing speed of the insulating film on the polished surface where the conductive metal and the insulating film coexist, there is a problem that the conductive metal part is easily cut into a dish shape, which is called a surface defect called dishing. It is required to solve this problem. [Means for solving the problem]

The present invention is made to solve at least a part of the above-mentioned problems and can be implemented as any of the following aspects.

One embodiment of the chemical mechanical polishing composition of the present invention contains silicon dioxide particles and a liquid medium, The ratio (Rmax/Rmin) of the long diameter (Rmax) to the short diameter (Rmin) of the silicon dioxide particles is greater than 2.5, The zeta potential of the silicon dioxide particles in the chemical mechanical polishing composition exceeds 0 mV.

In one embodiment of the chemical mechanical polishing composition, the average primary particle size of the silicon dioxide particles calculated based on the specific surface area measured using the Brunauer-Emmett-Teller (BET) method is 40 nm or less.

In any embodiment of the chemical mechanical polishing composition, the average secondary particle size of the silicon dioxide particles measured by dynamic light scattering is greater than 40 nm and less than 200 nm.

In any aspect of the chemical mechanical polishing composition, it may be: When the total mass of the chemical mechanical polishing composition is set to 100 mass %, the content of the silicon dioxide particles is greater than 0.1 mass % and less than 10 mass %.

In any aspect of the chemical mechanical polishing composition, it may be: It further contains an acidic compound.

In any aspect of the chemical mechanical polishing composition, it may: further contain an oxidizing agent.

In any aspect of the chemical mechanical polishing composition, the pH may be greater than 2 and less than 5.

One aspect of the chemical mechanical polishing method of the present invention includes the following steps: The step of polishing a semiconductor substrate using a chemical mechanical polishing composition of any aspect described above.

In one embodiment of the chemical mechanical polishing method, the semiconductor substrate includes a portion containing at least one selected from the group consisting of silicon oxide and tungsten. [Effect of the invention]

According to the chemical mechanical polishing composition of the present invention, a polishing surface on which a conductive metal such as tungsten or cobalt and an insulating film such as a silicon oxide film coexist can be polished at high speed and flatly, and the generation of surface defects after polishing can be reduced.

The following describes in detail suitable embodiments of the present invention. The present invention is not limited to the following embodiments, but includes various modifications that can be implemented without changing the gist of the present invention.

In this specification, "(meth)acrylic acid" means "acrylic acid" or "methacrylic acid".

In this specification, a numerical range described using “A to B” means that the numerical value A is included as a lower limit and the numerical value B is included as an upper limit.

1. Chemical Mechanical Polishing Composition A chemical mechanical polishing composition according to one embodiment of the present invention contains silicon dioxide particles and a liquid medium. The following is a detailed description of the components that may be included in the chemical mechanical polishing composition according to this embodiment.

1.1. Silica particles The chemical mechanical polishing composition of this embodiment contains silica particles as abrasive grain components. The ratio (Rmax/Rmin) of the major diameter (Rmax) to the minor diameter (Rmin) of the silica particles is 2.5 or more, and the azimuth potential in the chemical mechanical polishing composition exceeds 0 mV.

The zeta potential of the silicon dioxide particles in the chemical mechanical polishing composition is preferably 2 mV or more, more preferably 3 mV or more, further preferably 4 mV or more, and particularly preferably 5 mV or more. By using silicon dioxide particles having a zeta potential exceeding 0 mV, the dispersion stability of the silicon dioxide particles is improved due to electrostatic repulsion, thereby reducing the generation of surface defects such as scratches and increasing the polishing rate of the tungsten film or silicon oxide film. Furthermore, the zeta potential of the silicon dioxide particles in the chemical mechanical polishing composition can be measured using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model "DT300") or the like.

The average primary particle size of the silica particles calculated from the specific surface area measured using the BET method is preferably 40 nm or less, more preferably 5 nm or more and 35 nm or less, and particularly preferably 8 nm or more and 32 nm or less. If the average primary particle size of the silica particles is within the above range, the tungsten film and the silicon oxide film can be polished at a practical polishing rate, and the residue of the silica particles in the polished surface after CMP is reduced. The average primary particle size of the silica particles can be obtained by, for example, measuring the specific surface area by the BET method using a dynamic adsorption surface area automatic measuring device ("Micromeritics FlowSorb II 2300" manufactured by Micromeritics), and calculating and obtaining it based on the measured value.

The average secondary particle size of the silica particles in the chemical mechanical polishing composition measured using a dynamic light scattering method is preferably greater than 40 nm and less than 200 nm, and more preferably greater than 45 nm and less than 190 nm. If the average secondary particle size of the silica particles is within the range, a chemical mechanical polishing composition can be obtained, which can polish tungsten films and silicon oxide films at a practical polishing speed, and is less likely to produce sedimentation/separation of silica particles and has excellent storage stability, thereby reducing the occurrence of surface defects such as scratches. Furthermore, if the average secondary particle size of the silica particles is within the range, the silica particles are less likely to invade the fine wiring portion of the patterned substrate, and the polishing of the wiring portion can be suppressed, thereby improving the flatness. As particle size distribution measuring devices using the dynamic light scattering method as the measuring principle, there are: the nanoparticle analyzer "DelsaNano S" manufactured by Beckman-Coulter; the "Zetasizer nano zs" manufactured by Malvern; the "LB550" manufactured by Horiba, Ltd., etc. In addition, the average secondary particle size measured by the dynamic light scattering method represents the average particle size of secondary particles formed by the combination of multiple primary particles.

The ratio Rmax/Rmin of the major diameter (Rmax) to the minor diameter (Rmin) of the silicon dioxide particles used in this embodiment is 2.5 or more, preferably 2.6 to 10.0, more preferably 2.8 to 8.0, and particularly preferably 3.0 to 6.0. If the ratio Rmax/Rmin of the major diameter (Rmax) to the minor diameter (Rmin) of the silicon dioxide particles is within the above range, defects will not be caused in the tungsten film or silicon oxide film to be polished, and the tungsten film or silicon oxide film can be polished at a high speed, and both high polishing speed and high flattening characteristics can be taken into account.

Here, the long diameter (Rmax) of a silica particle refers to the longest diameter of the image of an independent silica particle photographed by a transmission electron microscope, connecting the ends of the image. The short diameter (Rmin) of a silica particle refers to the shortest diameter of the image of an independent silica particle photographed by a transmission electron microscope, connecting the ends of the image.

For example, as shown in FIG1, when the image of an independent silica particle 2a photographed by a transmission electron microscope is an elliptical shape, the long axis a of the elliptical shape is judged as the long diameter (Rmax) of the silica particle, and the short axis b is judged as the short diameter (Rmin) of the silica particle. As shown in FIG2, when the image of an independent silica particle 2b photographed by a transmission electron microscope is a combination of two primary particles, the longest diameter c in the straight line connecting the end of the image is judged as the long diameter (Rmax) of the silica particle, and the shortest diameter d in the straight line connecting the end of the image is judged as the short diameter (Rmin) of the silica particle. As shown in FIG3 , when the image of an independent silica particle 2c photographed by a transmission electron microscope is an aggregate of three or more primary particles, the longest diameter e among the straight lines connecting the ends of the image is judged to be the long diameter (Rmax) of the silica particle, and the shortest diameter f among the straight lines connecting the ends of the image is judged to be the short diameter (Rmin) of the silica particle.

By the determination method described above, for example, the major diameter (Rmax) and minor diameter (Rmin) of 50 independent silicon dioxide particles are measured, and the average values of the major diameter (Rmax) and minor diameter (Rmin) are calculated. Then, the average value of the major diameter is divided by the average value of the minor diameter, thereby obtaining the ratio Rmax/Rmin.

The shape of the silica particles used in this embodiment is preferably an aggregate of three or more primary particles, more preferably an aggregate of four or more primary particles, further preferably an aggregate of five or more primary particles, and particularly preferably an aggregate of six or more primary particles. In addition, as the aggregate, it is preferably an aggregate in which the primary particles form a chain structure. By having the shape of the silica particles being such an aggregate, the tungsten film or silicon oxide film can be polished at a higher speed, and the polishing speed of the silicon oxide film can be particularly increased.

As a method for producing silica particles, there can be cited a method of surface-modifying silica such as colloidal silica and fumed silica (hereinafter, also referred to as "raw silica") by the method described in Japanese Patent Laid-Open No. 2005-162533. As the raw silica, colloidal silica is preferred from the viewpoint of reducing polishing defects such as scratches, and colloidal silica produced by the method described in Japanese Patent Laid-Open No. 2003-109921 can be preferably used. Here, the raw silica used can use an average secondary particle size of 90 nm or more and 300 nm or less measured by a dynamic light scattering method.

As an example of a method for modifying the surface of raw silicon dioxide, a method of fixing a compound having a functional group represented by -SO ₃ ^- M ⁺ (M ⁺ represents a monovalent cation) on the surface of raw silicon dioxide via a covalent bond can be cited. The monovalent cation represented by M ⁺ is not limited to these, and examples thereof include: H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ .

When the total mass of the chemical mechanical polishing composition is set to 100 mass%, the lower limit of the content of the silicon dioxide particles is preferably 0.1 mass%, more preferably 0.5 mass%, and particularly preferably 1 mass%. When the total mass of the chemical mechanical polishing composition is set to 100 mass%, the upper limit of the content of the silicon dioxide particles is preferably 10 mass%, more preferably 8 mass%, and particularly preferably 5 mass%. If the content of the silicon dioxide particles is within the range, the following situation exists: for the polished surface where a conductive metal such as tungsten or cobalt and an insulating film such as a silicon oxide film coexist, it is possible to polish at a practical polishing rate while suppressing the occurrence of polishing defects.

1.2. Liquid medium The chemical mechanical polishing composition of this embodiment contains a liquid medium. Examples of the liquid medium include water, a mixed medium of water and alcohol, and a mixed medium containing water and an organic solvent that is compatible with water. Among these, water and a mixed medium of water and alcohol are preferably used, and water is more preferably used. There is no particular limitation on the water, and pure water is preferred. Water can be prepared as the remainder of the constituent materials of the chemical mechanical polishing composition, and the water content is not particularly limited.

1.3. Other additives The chemical mechanical polishing composition of this embodiment may further contain additives such as oxidants, acidic compounds, surfactants, water-soluble polymers, anti-corrosion agents, pH adjusters, etc. as needed. Each additive is described below.

<Oxidant> The chemical mechanical polishing composition of this embodiment may also contain an oxidant. By containing an oxidant, conductive metals such as tungsten and cobalt are oxidized to promote complex reactions with polishing liquid components, thereby generating a fragile modified layer on the polished surface, thereby increasing the polishing speed.

As the oxidizing agent, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, iron nitrate, diammonium nitrate, potassium hypochlorite, ozone, orthoperiodic acid, potassium periodate, peracetic acid, etc. are listed. Among these oxidizing agents, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferred, and hydrogen peroxide is more preferred in view of oxidizing power and ease of handling. These oxidizing agents may be used alone or in combination of two or more.

When the chemical mechanical polishing composition of the present embodiment contains an oxidizing agent, the content of the oxidizing agent is preferably 0.001 mass % to 5 mass %, more preferably 0.005 mass % to 4 mass %, and particularly preferably 0.1 mass % to 3 mass %, when the total mass of the chemical mechanical polishing composition is set to 100 mass %. Furthermore, the oxidizing agent is easily decomposed in the chemical mechanical polishing composition, so it is ideally added just before the CMP step.

<Acidic compound> The chemical mechanical polishing composition of this embodiment may also contain an acidic compound. By containing the acidic compound, the polishing speed is increased by the acidic compound being coordinated to the polished surface, and the precipitation of metal salts during polishing can be suppressed. In addition, by the acidic compound being coordinated to the polished surface, the damage to the polished surface caused by etching and corrosion can be reduced.

As such acidic compounds, organic acids and inorganic acids can be listed. Examples of organic acids include saturated carboxylic acids such as acetic acid, malonic acid, citric acid, apple acid, tartaric acid, oxalic acid, lactic acid, and iminodiacetic acid; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, 2-butenoic acid, 2-methyl-3-butenoic acid, 2-hexenoic acid, and 3-methyl-2-hexenoic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citric acid, mesaconic acid, 2-pentaconedioic acid, itaconic acid, allylmalonic acid, isopropylidene succinic acid, 2,4-hexadienedioic acid, and acetylenedicarboxylic acid; aromatic carboxylic acids such as trimellitic acid; aminocarboxylic acids such as glycine, alanine, aspartic acid, glutamine, lysine, tryptophan, arginine, histidine, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid, and salts thereof. Examples of the inorganic acid include phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and salts thereof. These acidic compounds may be used alone or in combination of two or more.

When the chemical mechanical polishing composition of this embodiment contains an acidic compound, when the total mass of the chemical mechanical polishing composition is set to 100 mass%, the content of the acidic compound is preferably 0.001 mass% to 5 mass%, more preferably 0.005 mass% to 1 mass%, and particularly preferably 0.01 mass% to 0.5 mass%.

<Surfactant> The chemical mechanical polishing composition of this embodiment may also contain a surfactant. By containing a surfactant, it is possible to impart a suitable viscosity to the chemical mechanical polishing composition. The viscosity of the chemical mechanical polishing composition is preferably adjusted to be 0.5 mPa·s or more and less than 10 mPa·s at 25°C.

The surfactant is not particularly limited, and examples thereof include anionic surfactants, cationic surfactants, nonionic surfactants, and the like.

Examples of anionic surfactants include: carboxylates such as fatty acid soaps and alkyl ether carboxylates; sulfonates such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, and α-olefin sulfonates; sulfates such as higher alcohol sulfates, alkyl ether sulfates, and polyoxyethylene alkylphenyl ether sulfates; fluorine-containing surfactants such as perfluoroalkyl compounds, etc. Examples of cationic surfactants include: aliphatic amine salts, aliphatic ammonium salts, etc. Examples of nonionic surfactants include: nonionic surfactants having triple bonds such as acetylene glycol, acetylene glycol ethylene oxide adducts, and acetylene alcohol; polyethylene glycol-type surfactants, etc. These surfactants may be used alone or in combination of two or more.

When the chemical mechanical polishing composition of this embodiment contains a surfactant, the content of the surfactant is preferably 0.001 mass % to 5 mass %, more preferably 0.003 mass % to 3 mass %, and particularly preferably 0.005 mass % to 1 mass %, when the total mass of the chemical mechanical polishing composition is set to 100 mass %.

<Water-soluble polymer> The chemical mechanical polishing composition of this embodiment may also contain a water-soluble polymer. The water-soluble polymer has the effect of adsorbing on the surface of the polished surface to reduce the polishing friction. Due to this effect, there is a possibility that the occurrence of polishing defects in the polished surface can be reduced.

Examples of water-soluble polymers include polyethyleneimine, poly(meth)acrylamine, poly(meth)acrylamide, polyethylene glycol, poly(meth)acrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, polystyrene sulfonic acid, hydroxyethyl cellulose, carboxymethyl cellulose, copolymers of (meth)acrylic acid and maleic acid, and the like.

The weight average molecular weight (Mw) of the water-soluble polymer is preferably 1,000 to 1,000,000, and more preferably 3,000 to 800,000. If the weight average molecular weight of the water-soluble polymer is within the above range, it is easy to adsorb on the polished surface of the conductive metal, etc., and the polishing friction can be further reduced. As a result, the occurrence of polishing defects in the polished surface can be more effectively reduced. Furthermore, the so-called "weight average molecular weight (Mw)" in this specification refers to the weight average molecular weight converted to polyethylene glycol measured by gel permeation chromatography (GPC).

When the chemical mechanical polishing composition of this embodiment contains a water-soluble polymer, the content of the water-soluble polymer is preferably 0.01 mass % to 1 mass %, and more preferably 0.03 mass % to 0.5 mass %, when the total mass of the chemical mechanical polishing composition is set to 100 mass %.

Furthermore, the content of the water-soluble polymer also depends on the weight average molecular weight (Mw) of the water-soluble polymer, and is preferably adjusted so that the viscosity of the chemical mechanical polishing composition at 25°C is 0.5 mPa·s or more and less than 10 mPa·s. If the viscosity of the chemical mechanical polishing composition at 25°C is 0.5 mPa·s or more and less than 10 mPa·s, it is easy to polish conductive metals at high speed and the viscosity is appropriate, so the chemical mechanical polishing composition can be stably supplied to the polishing pad.

<Anti-corrosion agent> The chemical mechanical polishing composition of this embodiment may also contain an anti-corrosion agent. As an anti-corrosion agent, for example, nitrogen-containing heterocyclic compounds and their derivatives can be listed. Here, the nitrogen-containing heterocyclic compound is an organic compound having at least one nitrogen atom and containing at least one heterocyclic ring selected from a heterocyclic five-membered ring and a heterocyclic six-membered ring. As specific examples of the heterocyclic ring, there can be listed: heterocyclic five-membered rings such as pyrrole structure, imidazole structure, triazole structure, thiazole structure, isothiazolinone structure; heterocyclic six-membered rings such as pyridine structure, pyrimidine structure, oxazine structure, pyrazine structure. The heterocyclic ring can also form a condensed ring. Specifically, the following can be cited: indole structure, isoindole structure, benzimidazole structure, benzotriazole structure, quinoline structure, isoquinoline structure, quinazoline structure, cinnoline structure, phthalazine structure, quinoxaline structure, acridine structure, etc. Among the nitrogen-containing heterocyclic compounds having such structures, preferred are nitrogen-containing heterocyclic compounds having isothiazolinone structure, thiazole structure, pyridine structure, quinoline structure, benzimidazole structure, and benzotriazole structure, and more preferred are nitrogen-containing heterocyclic compounds having isothiazolinone structure or thiazole structure.

Specific examples of nitrogen-containing heterocyclic compounds include aziridine, pyridine, pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzoisoquinoline, purine, pteridine, triazole, triazolidine, benzotriazole, 4-carboxybenzotriazole, 7-carboxybenzotriazole, benzotriazole butyl ester, 1-hydroxymethylbenzotriazole, 1-hydroxybenzotriazole, thiazole, benzothiazole, 4-bromothiazole, 2-chlorothiazole, 2-hydroxybenzothiazole, 2-(methylthio)benzothiazole, 2-chlorobenzothiazole, 2-methylbenzothiazole, 5-methoxy-2-methylbenzothiazole, 2-methyl-4,5,7-trifluorobenzothiazole, 2-aminobenzothiazole, Benzothiazole, 2-amino-6-methylbenzothiazole, 2-amino-4-methoxybenzothiazole, 4-methyl-2-hydroxybenzothiazole, 3-chloro-1,2-benzoisothiazole, 2-(2-hydroxyphenyl)benzothiazole, thiazoline, chlorothiazoline, isothiazolinone, 1,2-benzoisothiazoline-3-one, 2-methyl-4,5-triazine Methylene-4-isothiazoline-3-one, 2-methyl-4-isothiazoline-3-one, 5-chloro-2-methyl-4-isothiazoline-3-one, N-n-butyl-1,2-benzoisothiazoline-3-one, 4,5-dichloro-2-n-octyl-isothiazoline-3-one, 2-n-octyl-4-isothiazoline-3-one and salts thereof. These nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more.

When the chemical mechanical polishing composition of this embodiment contains an anti-corrosion agent, the content of the anti-corrosion agent is preferably 1 mass % or less, and more preferably 0.001 mass % to 0.1 mass % when the total mass of the chemical mechanical polishing composition is 100 mass %.

<pH adjuster> The chemical mechanical polishing composition of this embodiment may further contain a pH adjuster as needed. Examples of pH adjusters include potassium hydroxide, ethylenediamine, monoethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), ammonia and other bases, and more than one of these may be used.

1.4. pH The pH of the chemical mechanical polishing composition of this embodiment is not particularly limited, but is preferably 2 or more and 7.5 or less, more preferably 2 or more and 6 or less, further preferably 2 or more and 5 or less, and particularly preferably 2 or more and 4 or less. If the pH is within the above range, the dispersibility of the silica particles in the chemical mechanical polishing composition is improved, thereby improving the storage stability of the chemical mechanical polishing composition, which is preferred.

Furthermore, the pH of the chemical mechanical polishing composition of this embodiment can be adjusted by, for example, appropriately increasing or decreasing the content of the acidic compound or the pH adjuster.

In the present invention, pH refers to the hydrogen ion index, which can be measured at 25°C and 1 atmosphere using a commercially available pH meter (e.g., a desktop pH meter manufactured by Horiba, Ltd.).

1.5. Application The chemical mechanical polishing composition of this embodiment is suitable as a polishing material for chemical mechanical polishing of a semiconductor substrate having a plurality of materials constituting a semiconductor device. For example, the semiconductor substrate may have an insulating film material such as a silicon oxide film, a silicon nitride film, or amorphous silicon, or a barrier metal material such as titanium, titanium nitride, or tantalum nitride, in addition to a conductive metal such as tungsten or cobalt.

The chemical mechanical polishing composition of this embodiment is particularly suitable for polishing a workpiece such as a semiconductor substrate provided with a wiring layer containing tungsten. Specifically, the workpiece includes a silicon oxide film having a through hole and a tungsten film provided on the silicon oxide film via a barrier metal film. By using the chemical mechanical polishing composition of this embodiment, not only can the tungsten film be polished at high speed and flatly, but also the polishing surface where the tungsten film and an insulating film such as a silicon oxide film coexist can be polished at high speed and flatly while suppressing the occurrence of polishing defects.

1.6. Preparation method of chemical mechanical polishing composition The chemical mechanical polishing composition of this embodiment can be prepared by dissolving or dispersing the above-mentioned components in a liquid medium such as water. There is no particular limitation on the method of dissolving or dispersing, and any method can be applied as long as it can be dissolved or dispersed uniformly. In addition, there is no particular limitation on the mixing order and mixing method of the above-mentioned components.

In addition, the chemical mechanical polishing composition of this embodiment can also be prepared in the form of a concentrated stock solution and diluted with a liquid medium such as water before use.

2. Chemical mechanical polishing method A chemical mechanical polishing method according to an embodiment of the present invention includes the step of polishing a semiconductor substrate using the chemical mechanical polishing composition. A specific example of the chemical mechanical polishing method according to this embodiment is described in detail below using a diagram.

2.1. Object to be processed FIG4 is a cross-sectional view schematically showing an object to be processed that is suitable for the chemical mechanical polishing method of this embodiment. The object to be processed 100 is formed by going through the following steps (1) to (4).

(1) First, as shown in FIG. 4 , a substrate 10 is prepared. The substrate 10 may include, for example, a silicon substrate and a silicon oxide film formed thereon. Furthermore, functional devices such as transistors (not shown) may also be formed on the substrate 10. Next, a silicon oxide film 12 serving as an insulating film is formed on the substrate 10 using a thermal oxidation method.

(2) Next, the silicon oxide film 12 is patterned. Using the obtained pattern as a mask, a through hole 14 is formed in the silicon oxide film 12 by photolithography.

(3) Then, a barrier metal film 16 is formed on the surface of the silicon oxide film 12 and the inner wall surface of the through hole 14 by sputtering or the like. Tungsten and silicon have poor electrical contact, so good electrical contact is achieved by the presence of the barrier metal film in between. Examples of the barrier metal film 16 include titanium and/or titanium nitride.

(4) Next, a tungsten film was deposited using chemical vapor deposition (CVD)18.

Through the above steps, the object to be processed 100 is formed.

2.2. Chemical mechanical polishing method 2.2.1. First polishing step FIG. 5 is a schematic cross-sectional view of the treated body at the end of the first polishing step. In the first polishing step, as shown in FIG. 5 , the tungsten film 18 is polished using the chemical mechanical polishing composition until the barrier metal film 16 is exposed.

2.2.2. Second polishing step FIG. 6 is a schematic cross-sectional view of the object to be processed at the end of the second polishing step. In the second polishing step, as shown in FIG. 6 , the silicon oxide film 12, the barrier metal film 16, and the tungsten film 18 are polished using the chemical mechanical polishing composition. By going through the second polishing step, a next-generation semiconductor device 200 having excellent flatness of the polished surface can be manufactured.

Furthermore, as described above, the chemical mechanical polishing composition is suitable as a polishing material for chemical mechanical polishing of a semiconductor substrate having a plurality of materials constituting a semiconductor device. Therefore, in the first polishing step and the second polishing step of the chemical mechanical polishing method of this embodiment, the chemical mechanical polishing composition of the same composition can be used, thereby improving the throughput of the production line.

2.3. Chemical mechanical polishing device In the first polishing step and the second polishing step, for example, a polishing device 300 as shown in FIG. 7 can be used. FIG. 7 is a schematic perspective view of the polishing device 300. The first polishing step and the second polishing step are performed as follows: a slurry (chemical mechanical polishing composition) 44 is supplied from a slurry supply nozzle 42, and a turntable 48 with a polishing pad 46 attached is rotated, while a carrier head 52 holding a semiconductor substrate 50 is abutted. Furthermore, in FIG. 7, a water supply nozzle 54 and a dresser 56 are also shown.

The grinding load of the carrier head 52 can be selected in the range of 10 hPa to 980 hPa, preferably 30 hPa to 490 hPa. In addition, the rotation speed of the turntable 48 and the carrier head 52 can be appropriately selected in the range of 10 rpm to 400 rpm, preferably 30 rpm to 150 rpm. The flow rate of the slurry (chemical mechanical grinding composition) 44 supplied from the slurry supply nozzle 42 can be selected in the range of 10 mL/min to 1,000 mL/min, preferably 50 mL/min to 400 mL/min.

Examples of commercially available polishing devices include: EBARA Mfg. Co., Ltd.'s models "EPO-112" and "EPO-222"; Lapmaster SFT's models "LGP-510" and "LGP-552"; Applied Materials' models "Mirra" and "Reflexion"; G&P TECHNOLOGY's model "POLI-400L"; and AMAT's model "Reflexion LK."

3. Examples The present invention is described below by using examples, but the present invention is not limited by these examples. In addition, the "parts" and "%" in this example are based on mass unless otherwise specified.

3.1. Preparation of aqueous dispersion of silica particles 3.1.1. Preparation of aqueous dispersion A 7500 g of pure water as a solvent was placed in a flask, and 1.31 g of triethylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 80°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxy silane (TMOS) was added dropwise at a constant rate over 60 minutes to prepare a mixed solution. After stirring for 15 minutes, 49.22 g of triethylamine was added to the mixed solution to prepare a seed particle dispersion. Then, 800 g of the seed particle dispersion was taken. Subsequently, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 650 mL of pure water was added dropwise while the seed particle dispersion was heated to an internal temperature in the range of 70°C to 90°C, while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion A of colloidal silica.

3.1.2. Preparation of aqueous dispersion B 7500 g of pure water as a solvent was placed in a flask, and 0.91 g of triethylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 75°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 60 minutes to prepare a mixed solution. After stirring for 15 minutes, 41.25 g of triethylamine was added to the mixed solution to prepare a seed particle dispersion. Then, 800 g of the seed particle dispersion was taken. Subsequently, in order to remove the methanol produced as a by-product during the reaction by distillation out of the system, 650 mL of pure water was added dropwise while the seed particle dispersion was heated to an internal temperature in the range of 70°C to 90°C while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion B of colloidal silica.

3.1.3. Preparation of aqueous dispersion C 7500 g of pure water as a solvent was placed in a flask, and 0.465 g of 3-butoxypropylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 80°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 120 minutes to prepare a mixed solution. After stirring for 180 minutes, 50.12 g of 3-butoxypropylamine was added to the mixed solution to prepare a seed particle dispersion. Subsequently, 2331 g of the seed particle dispersion and 5265 g of pure water were placed in another flask. Afterwards, the internal temperature was heated to 80°C, and the temperature was adjusted in such a way that the internal temperature did not change. At the same time, 2000 g of tetramethoxysilane (TMOS) was dripped at a constant rate over 180 minutes. After the dripping was completed, the liquid containing silica was prepared by stirring for 15 minutes. Next, 800 g of the liquid containing silica was taken. Afterwards, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 550 mL of pure water was dripped while the internal temperature of the silica-containing liquid was heated to a range of 70°C to 90°C while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion C of colloidal silica.

3.1.4. Preparation of aqueous dispersion D 7500 g of pure water as a solvent was placed in a flask, and 0.338 g of 3-ethoxypropylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 60°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 60 minutes to prepare a mixed solution. After stirring for 60 minutes, 30.44 g of 3-ethoxypropylamine was added to the mixed solution to prepare a seed particle dispersion. Then, 800 g of the seed particle dispersion was taken. Subsequently, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 650 mL of pure water was added dropwise while the seed particle dispersion was heated to an internal temperature in the range of 70°C to 90°C, while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion D of colloidal silica.

3.1.5. Preparation of aqueous dispersion E 4500 g of pure water and 3000 g of methanol as solvents were placed in a flask, and 0.525 g of 3-ethoxypropylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 80°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 120 minutes to prepare a mixed solution. After stirring for 240 minutes, 50.12 g of 3-ethoxypropylamine was added to the mixed solution to prepare a seed particle dispersion. Subsequently, 2331 g of the seed particle dispersion and 5265 g of pure water were placed in another flask. Afterwards, the internal temperature was heated to 80°C, and the temperature was adjusted in such a way that the internal temperature did not change. At the same time, 1500 g of tetramethoxysilane (TMOS) was dripped at a constant rate over 180 minutes. After the dripping was completed, the liquid containing silica was prepared by stirring for 15 minutes. Next, 800 g of the liquid containing silica was taken. Afterwards, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 650 mL of pure water was dripped while the internal temperature of the silica-containing liquid was heated to a range of 70°C to 90°C while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion E of colloidal silica.

3.1.6. Preparation of aqueous dispersion F 4500 g of pure water and 3000 g of methanol as solvents were placed in a flask, and 1.04 g of triethylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 75°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 60 minutes to prepare a mixed solution. After stirring for 15 minutes, 53.11 g of triethylamine was added to the mixed solution to prepare a seed particle dispersion. Then, 800 g of the seed particle dispersion was taken. Subsequently, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 650 mL of pure water was added dropwise while the seed particle dispersion was heated to an internal temperature in the range of 70°C to 90°C, while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion F of colloidal silica.

3.1.7. Preparation of aqueous dispersion G 7500 g of pure water as a solvent was placed in a flask, and 1.16 g of dipropylamine as an alkaline catalyst was added to prepare a mother solution. After the mother solution was heated to an internal temperature of 80°C, the temperature was adjusted in the mother solution without changing the internal temperature, and 2720 g of tetramethoxysilane (TMOS) was added dropwise at a constant rate over 90 minutes to prepare a mixed solution. After stirring for 15 minutes, 50.25 g of dipropylamine was added to the mixed solution to prepare a seed particle dispersion. Then, 800 g of the seed particle dispersion was taken. Subsequently, in order to distill and remove the methanol produced as a by-product during the reaction out of the system, 600 mL of pure water was added dropwise while the seed particle dispersion was heated to an internal temperature in the range of 70°C to 90°C while maintaining a constant volume, thereby replacing the dispersion medium and obtaining a water dispersion G of colloidal silica.

3.1.8. Preparation of aqueous dispersion H Put 400 g of aqueous dispersion A and 0.83 g of (3-aminopropyl)triethoxysilane in a flask to prepare a mixed solution. Heat the mother solution to an internal temperature of 60°C and stir for 120 minutes to obtain aqueous dispersion H of colloidal silica.

3.1.9. Preparation of aqueous dispersion I Colloidal silica used in Example 1 of International Publication No. 2008/117592 was prepared and used as aqueous dispersion I.

3.1.10. Preparation of aqueous dispersion containing commercially available colloidal silica Colloidal silica (product numbers: BS-3, PL-3-D) manufactured by Fuso Chemical Industries, Ltd. was purchased and used directly.

3.2. Evaluation of the shape of silica particles 50 silica particles were randomly selected and observed at 30,000 times using a transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, model "H-7000") from aqueous dispersions A to I or colloidal silica manufactured by Fuso Chemical Industries, Ltd. For the 50 silica particles, the major diameter (Rmax) and minor diameter (Rmin) were measured respectively, and the average values of the major diameter (Rmax) and minor diameter (Rmin) were calculated. The average value of the major diameter was divided by the average value of the minor diameter to obtain the value of Rmax/Rmin. The results are shown in Tables 1 and 2 below.

3.3. Measurement of average primary particle size of silica particles The silica particles contained in aqueous dispersions A to I or colloidal silica (product number: BS-3, PL-3-D) manufactured by Fuso Chemical Industries, Ltd. were pre-dried on a hot plate and then heat-treated at 800°C for 1 hour to prepare a sample for measurement. The BET specific surface area was measured using the flow-type specific surface area automatic measuring device "Micrometrics FlowSorb II 2300 (manufactured by Shimadzu Corporation)" using the sample for measurement. The average primary particle size (nm) of silica particles in colloidal silica was calculated by converting the value of 2727/BET specific surface area (m ² /g) by setting the true specific gravity of silica to 2.2. The results are shown in Tables 1 and 2 below.

3.4. Preparation of chemical mechanical polishing composition A predetermined amount of the aqueous dispersion prepared above was placed in a polyethylene bottle with a capacity of 1000 ^cm3 , and the compounds listed in Table 1 or Table 2 were added thereto in the amounts listed in Table 1 or Table 2, respectively, and stirred thoroughly. Furthermore, after adding ion-exchanged water, the mixture was filtered using a filter with a pore size of 5 μm to obtain chemical mechanical polishing compositions of Examples 1 to 16 and Comparative Examples 1 to 4.

3.5. Measurement of the zeta potential of silicon dioxide particles in the chemical mechanical polishing composition For the chemical mechanical polishing compositions of Examples 1 to 16 and Comparative Examples 1 to 4, the zeta potential of silicon dioxide particles was measured using an acoustic and electroacoustic spectrometer (manufactured by Dispersion Technologies, model "DT300"). The results are shown in Tables 1 and 2 below.

3.6. Measurement of average secondary particle size of silica particles in chemical mechanical polishing composition For the chemical mechanical polishing compositions of Examples 1 to 16 and Comparative Examples 1 to 4, the arithmetic mean diameter of silica particles in the chemical mechanical polishing composition was measured using a dynamic light scattering particle size distribution measuring device (manufactured by Horiba, Ltd., model "LB550"), and the value was regarded as the average secondary particle size. The results are shown in Tables 1 and 2 below.

3.7. Evaluation method 3.7.1. Polishing speed test Using the chemical mechanical polishing compositions of Examples 1 to 16 and Comparative Examples 1 to 4, a 12-inch diameter wafer with a 300 nm p-tetraethyl orthosilicate (TEOS) film (silicon oxide film) or a 12-inch diameter wafer with a 300 nm CVD-tungsten film was used as the polished object, and a chemical mechanical polishing test was performed for 60 seconds under the following polishing conditions.

<Polishing conditions> ·Polishing device: manufactured by AMAT, model "Reflexion LK" ·Polishing pad: manufactured by Fujibo Holdings, "polyurethane pad; H800-type1 (3-1S) 775" ·Chemical mechanical polishing composition supply rate: 300 mL/min ·Platen speed: 100 rpm ·Head speed: 90 rpm ·Head pressing pressure: 2.5 psi ·Polishing speed (Å/min) = (film thickness before polishing - film thickness after polishing) / polishing time

The thickness of the p-TEOS film was evaluated using an optical interferometer film thickness meter "NanoSpec 6100" (manufactured by Nanometrics Japan). The thickness of the tungsten film was measured using a resistivity meter (manufactured by KLA-Tencor, model "OmniMap RS100") using the DC 4-probe method, and the sheet resistance value and the volume resistivity of tungsten were calculated using the following formula. Film thickness (Å) = [volume resistivity of tungsten film (Ω·m) ÷ sheet resistance value (Ω)] × 10 ¹⁰

The evaluation criteria of the polishing rate test are as follows. The evaluation results of the polishing rate of the p-TEOS film and the evaluation results of the polishing rate of the tungsten film are shown together in Tables 1 and 2 below.

<Evaluation criteria for polishing rate of p-TEOS film> · "A"···When the polishing rate of p-TEOS film is 3000 Å/min or more, the semiconductor can be processed very efficiently in actual semiconductor polishing, so it is judged to be extremely good. · "B"···When the polishing rate of p-TEOS film is 2000 Å/min or more and less than 3000 Å/min, the semiconductor can be processed efficiently in actual semiconductor polishing, so it is judged to be very good. · "C"···When the polishing rate of the p-TEOS film is 1000 Å/min or more and less than 2000 Å/min, the semiconductor can be processed within the allowable time in actual semiconductor polishing, so it is judged as good. · "D"···When the polishing rate of the p-TEOS film is less than 1000 Å/min, the semiconductor yield is hindered in actual semiconductor polishing, so it is judged as unsatisfactory.

<Evaluation criteria for tungsten film polishing speed> · "A"···When the polishing speed of the tungsten film is 500 Å/min or more, the semiconductor can be processed very efficiently in actual semiconductor polishing, so it is judged to be extremely good. · "B"···When the polishing speed of the tungsten film is 200 Å/min or more and less than 500 Å/min, the semiconductor can be processed efficiently in actual semiconductor polishing, so it is judged to be very good. · "C"···When the polishing rate of the tungsten film is 100 Å/min or more and less than 200 Å/min, the semiconductor can be processed within the allowable time in actual semiconductor polishing, so it is judged as good. · "D"···When the polishing rate of the tungsten film is less than 100 Å/min, the semiconductor yield is hindered in actual semiconductor polishing, so it is judged as unsatisfactory.

3.7.2. Defect test Using the chemical mechanical polishing compositions of Examples 1 to 16 and Comparative Examples 1 to 4, a 12-inch diameter wafer with a 300 nm p-TEOS film was used as the polished object, and a chemical mechanical polishing test was performed for 60 seconds under the following polishing conditions.

<Polishing conditions> ·Polishing device: manufactured by AMAT, model "Reflexion LK" ·Polishing pad: manufactured by Fujibo Holdings, "polyurethane pad; H800-type1 (3-1S) 775" ·Chemical mechanical polishing composition supply rate: 300 mL/min ·Platen speed: 100 rpm ·Head speed: 90 rpm ·Head pressing pressure: 2.5 psi

For wafers with p-TEOS films after the chemical mechanical polishing test, defects larger than 0.115 μm were observed using a defect inspection device (manufactured by KLA-Tencor, model "Surfscan SP2") in dark field mode. Then, the observer used a review scanning electron microscope (SEM) device (manufactured by Hitachi High-Technologies Corporation, model "RS6000") to visually inspect the defects and classify them into scratches, abrasive residues, or other than the above, and counted the number of scratches and abrasive residues, respectively.

The evaluation criteria of the defect test are as follows. The results of the number of scratches and the number of residual abrasive particles are shown in Tables 1 and 2 below.

<Evaluation criteria for the number of scratches> · "A"···When the total number of scratches is less than 10, it is extremely unlikely to cause quality defects in actual semiconductor polishing, so it is judged to be extremely good. · "B"···When the total number of scratches is 10 or more and less than 20, it is sufficiently unlikely to cause quality defects in actual semiconductor polishing, so it is judged to be very good. · "C"···When the total number of scratches is 20 or more and less than 30, the frequency of quality defects in actual semiconductor polishing is within the allowable range, so it is judged to be good. · "D"···When the total number of scratches is 30 or more, it is likely to cause quality problems and malfunctions in actual semiconductor polishing, so it is judged as defective.

<Evaluation criteria for the number of abrasive residues> · "A"···When the total number of abrasive residues is less than 20, it is extremely unlikely to cause quality defects in actual semiconductor polishing, so it is judged to be extremely good. · "B"···When the total number of abrasive residues is 20 or more and less than 40, it is sufficiently unlikely to cause quality defects in actual semiconductor polishing, so it is judged to be very good. · "C"···When the total number of abrasive residues is 40 or more and less than 60, the frequency of quality defects in actual semiconductor polishing is within the allowable range, so it is judged to be good. · "D"···When the total number of abrasive grains remaining is 60 or more, poor quality and malfunctions are likely to occur in actual semiconductor polishing, so it is judged as defective.

3.8. Evaluation results The types and physical properties of the silica particles used in each embodiment and each comparative example, the composition of the chemical mechanical polishing composition, and the evaluation results are shown in Tables 1 and 2 below.

[Table 1] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Embodiment 10 Compositions for chemical mechanical polishing Silicon dioxide particles Type Aqueous Dispersion A Aqueous Dispersion B Aqueous Dispersion C Aqueous dispersion D Aqueous Dispersion E Aqueous Dispersion F Aqueous dispersion G Aqueous Dispersion A Aqueous Dispersion H Aqueous Dispersion A Rmax/Rmin 4.3 5.8 2.6 7.1 2.6 2.8 4.4 4.3 5.8 4.3 Average primary particle size (nm) 16 16 31 10 43 62 9 16 16 16 The relative potential of the components (mV) twenty one 5 29 3 twenty three 18 6 3 4 5 Average secondary particle size in the composition (nm) 88 112 99 86 118 184 49 91 91 88 Content (mass %) 2.5 1.0 6.0 4.0 0.2 9.0 4.0 20.0 1.0 2.0 Other additives Type Maleic acid sulfuric acid Phosphoric acid Acetic acid Maleic acid sulfuric acid Phosphoric acid Citric Acid Phosphoric acid Content (mass %) 0.02 0.30 0.18 0.01 0.01 0.02 0.01 0.20 0.02 Type Content (mass %) Type Monoethanolamine Sodium dodecylbenzenesulfonate 2-Methyl-4-isothiazolin-3-one Polyacrylic acid Potassium Hydroxide Polyethylene glycol Tetraethylammonium hydroxide Content (mass %) 0.370 0.001 0.020 0.010 0.090 0.001 0.030 pH 3.0 3.6 2.1 4.5 3.1 4.0 3.0 4.9 7.4 5.5 Evaluation items Grinding speed Evaluation of polishing speed of p-TEOS film A C B C C B C B C C Evaluation of Tungsten Film Polishing Speed B B B C C B B B B B Defect evaluation Scratch number evaluation A A A A A C A B A A Evaluation of the number of abrasive particles remaining A A A C A A C A A A

[Table 2] Embodiment 11 Embodiment 12 Embodiment 13 Embodiment 14 Embodiment 15 Embodiment 16 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Compositions for chemical mechanical polishing Silicon dioxide particles Type Aqueous Dispersion A Aqueous dispersion D Aqueous Dispersion E Aqueous Dispersion A Aqueous dispersion D Aqueous Dispersion H BS-3 Aqueous Dispersion A PL-3-D Aqueous Dispersion I Rmax/Rmin 4.3 7.1 2.6 4.3 7.1 5.8 2.3 4.3 1.4 1.7 Average primary particle size (nm) 16 10 43 16 10 16 33 16 34 15 The relative potential of the components (mV) 15 11 9 36 8 43 3 -33 -9 -8 Average secondary particle size in the composition (nm) 88 86 118 88 86 91 71 93 69 27 Content (mass %) 3.0 6.0 1.0 2.0 15.0 5.0 0.5 3.0 3.0 3.0 Other additives Type Trimellitic acid Nitric Acid Phosphoric acid Nitric Acid sulfuric acid Maleic acid Malonic acid Nitric Acid tartaric acid Content (mass %) 0.11 0.02 0.35 0.05 0.02 0.16 0.01 0.02 1.00 Type Hydrogen peroxide Iron nitrate Periodic acid Content (mass %) 3.000 0.010 0.100 Type Lauryl imino dipropionic acid sodium salt ammonia Polyvinylpyrrolidone Histidine Polyethylene glycol ammonia Polystyrene sulfonic acid Tetramethylammonium hydroxide Content (mass %) 0.005 0.050 0.020 0.001 0.050 0.150 0.020 3.900 pH 3.7 2.2 4.0 2.1 4.1 2.1 4.3 10.8 3.0 4.0 Evaluation items Grinding speed Evaluation of polishing speed of p-TEOS film A B C B B A C D D D Evaluation of Tungsten Film Polishing Speed A A A B B B C B D D Defect evaluation Scratch number evaluation A B A A C A B D A D Evaluation of the number of abrasive particles remaining A C A A C C D B A D

The following products or reagents are used for each component in Table 1 and Table 2 above. <Acidic compounds> ·Maleic acid: manufactured by Fuso Chemical Industries, trade name "purified maleic acid" ·Acetic acid: manufactured by Fuji Film & Wako Pure Chemical Industries, trade name "acetic acid" ·Citric acid: manufactured by Fuso Chemical Industries, trade name "purified citric acid (crystallized) L" ·Malonic acid: manufactured by Fuji Film & Wako Pure Chemical Industries, trade name "malonic acid" ·Tartaric acid: manufactured by Fuji Film & Wako Pure Chemical Industries, trade name "tartaric acid" ·Trimellitate: manufactured by Fuji Film & Wako Pure Chemical Industries, trade name "trimellitate" ·Histidine: manufactured by Tokyo Chemical Industry, trade name "L-histidine" ·Sulfuric acid: manufactured by Kanto Chemical Industries, trade name "sulfuric acid" · Phosphoric acid: manufactured by Kanto Chemical Co., Ltd., trade name "Phosphoric acid" · Nitric acid: manufactured by Kanto Chemical Co., Ltd., trade name "Nitric acid 1.38" <Oxidant> · Hydrogen peroxide: manufactured by Fuji Film Wako Pure Chemical Co., Ltd., trade name "Hydrogen peroxide (30%)" · Ferric nitrate: manufactured by Tama Chemical Co., Ltd., trade name "FN-376" · Periodic acid: manufactured by Fuji Film Wako Pure Chemical Co., Ltd., trade name "Periodic acid" <Surfactant> · Sodium dodecylbenzenesulfonate: manufactured by Fuji Film Wako Pure Chemical Co., Ltd., trade name "Sodium dodecylbenzenesulfonate" · Monosodium lauryl iminodipropionate: manufactured by Takemoto Oil & Fats Co., Ltd., trade name "Takesurf C-158-G" ＜Water-soluble polymer＞ · Polyacrylic acid: manufactured by Toa Gosei Co., Ltd., trade name "Julimar AC-10L", weight average molecular weight (Mw) = 25,000 · Polyethylene glycol: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 20,000", weight average molecular weight (Mw) = 20,000 · Polyvinyl pyrrolidone: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "Polyvinyl pyrrolidone (Mw 40,000)", weight average molecular weight (Mw) = 40,000 · Polystyrene sulfonic acid: manufactured by Toyama Pharmaceutical Industries, Ltd., trade name "FUNCHEM-PSSH (10)", weight average molecular weight (Mw) = 14,000 (10% aqueous solution) ＜Corrosion inhibitor＞ ·2-Methyl-4-isothiazolin-3-one: manufactured by Sigma-Aldrich, trade name "2-Methyl-4-isothiazolin-3-one (2-Methyl-4-isothiazolin-3-on)" ＜pH adjuster＞ ·Monoethanolamine: manufactured by Nippon Catalyst Co., Ltd., trade name "Ethanolamine" ·Potassium hydroxide: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "Potassium hydroxide" ·Tetramethylammonium hydroxide: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Tetramethylammonium Hydroxide (10% in Water)" ·Tetraethylammonium hydroxide: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Tetraethylammonium hydroxide (10% in water)" ·Ammonia: manufactured by Fuji Film Wako Pure Chemical Co., Ltd., trade name "25% ammonia water"

According to the evaluation results in Tables 1 and 2 above, when using the chemical mechanical polishing composition of Examples 1 to 16 containing silicon dioxide particles having an Rmax/Rmin of 2.5 or more and a planar potential exceeding 0 mV as measured by a transmission electron microscope, p-TEOS films and tungsten films can be polished at a practical polishing speed and a speed balance for the two films can be easily ensured, and defects after polishing (scratches and abrasive particle residues) can be intentionally reduced.

In contrast, in the case of the chemical mechanical polishing composition of Comparative Example 1 containing silicon dioxide particles having an Rmax/Rmin of less than 2.5 as measured by a transmission electron microscope, an increase in the number of abrasive grains remaining outside the allowable range was observed.

On the other hand, when the chemical mechanical polishing composition of Comparative Example 2 was used, in which the zeta potential measured by acoustic and electronic acoustic spectrometers was less than 0 mV, the polishing rate of the p-TEOS film was low, so in addition to the poor yield in semiconductor manufacturing, the number of scratches was outside the allowable range.

When using the chemical mechanical polishing composition of Comparative Example 3 containing silicon dioxide particles having an Rmax/Rmin of less than 2.5 as measured by a transmission electron microscope and a zeta potential of less than 0 mV as measured by an acoustic and electron acoustic spectrometer, it was found that the polishing rates of both the p-TEOS film and the tungsten film were low, and there were problems with the yield in semiconductor manufacturing.

Comparative Example 4 is the evaluation result when the chemical mechanical polishing composition of Example 1 described in International Publication No. 2008/117592 is used. The silicon dioxide particles used have an Rmax/Rmin ratio of 1.7 measured using a transmission electron microscope and a zeta potential of -8 mV measured using an acoustic and electron acoustic spectrometer. In this case, the polishing rate and defect evaluation results are both inferior compared to the examples.

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes structures that are substantially the same as the structures described in the embodiments (e.g., structures with the same functions, methods, and results, or structures with the same purposes and effects). In addition, the present invention includes structures in which the non-essential parts of the structures described in the embodiments are replaced. In addition, the present invention includes structures that exert the same effects as the structures described in the embodiments, or structures that can achieve the same purposes. In addition, the present invention includes structures obtained by adding known technologies to the structures described in the embodiments.

2a, 2b, 2c: silicon dioxide particles 10: substrate 12: silicon oxide film 14: through hole 16: barrier metal film 18: tungsten film 42: slurry supply nozzle 44: slurry (chemical mechanical polishing composition) 46: polishing pad 48: turntable 50: semiconductor substrate 52: carrier head 54: water supply nozzle 56: dresser 100: processed body 200: semiconductor device 300: polishing device a: major axis b: minor axis c, d, e, f: diameter

FIG. 1 is an explanatory diagram schematically showing the concept of the long diameter and short diameter of a silica particle. FIG. 2 is an explanatory diagram schematically showing the concept of the long diameter and short diameter of a silica particle. FIG. 3 is an explanatory diagram schematically showing the concept of the long diameter and short diameter of a silica particle. FIG. 4 is a cross-sectional diagram schematically showing a processed body used in the chemical mechanical polishing method of the present embodiment. FIG. 5 is a cross-sectional diagram schematically showing a processed body after a first polishing step. FIG. 6 is a cross-sectional diagram schematically showing a processed body after a second polishing step. FIG. 7 is a perspective diagram schematically showing a polishing device.

Claims (9)

A chemical mechanical polishing composition comprising silicon dioxide particles and a liquid medium, wherein in the chemical mechanical polishing composition, the ratio (Rmax/Rmin) of the long diameter (Rmax) to the short diameter (Rmin) of the silicon dioxide particles is greater than 2.5, and the zeta potential of the silicon dioxide particles in the chemical mechanical polishing composition exceeds 0 mV. The chemical mechanical polishing composition according to claim 1, wherein the average primary particle size of the silica particles calculated from the specific surface area measured using the Bouter method is 40 nm or less. The chemical mechanical polishing composition according to claim 1 or 2, wherein the average secondary particle size of the silica particles measured using a dynamic light scattering method is 40 nm or more and 200 nm or less. The chemical mechanical polishing composition according to claim 1 or 2, wherein the content of the silicon dioxide particles is 0.1 mass % or more and 10 mass % or less, when the total mass of the chemical mechanical polishing composition is 100 mass %. The chemical mechanical polishing composition as described in claim 1 or 2 further contains an acidic compound. The chemical mechanical polishing composition as described in claim 1 or 2 further contains an oxidizing agent. The chemical mechanical polishing composition according to claim 1 or 2, wherein the pH is greater than or equal to 2 and less than or equal to 5. A chemical mechanical polishing method comprises the step of polishing a semiconductor substrate using the chemical mechanical polishing composition as described in claim 1 or 2. The chemical mechanical polishing method as described in claim 8, wherein the semiconductor substrate includes a portion containing at least one selected from the group consisting of silicon oxide and tungsten.