TWI842954B - Composition for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

The present invention provides a chemical mechanical polishing composition and a chemical mechanical polishing method, which 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 high speed and flatly, and can reduce surface defects after polishing. The chemical mechanical polishing composition of the present invention contains: (A) silicon dioxide particles modified with a compound having two or more amine groups; and (B) a liquid medium.

Description

Composition for chemical mechanical polishing and chemical mechanical polishing method

The present invention relates to a chemical mechanical polishing composition and a chemical 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 using chemical mechanical polishing (hereinafter also referred to as "CMP (Chemical Mechanical Polishing)") 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, as the wiring layer has become more miniaturized, tungsten (W) or cobalt (Co) has begun to be used as a conductive metal. Therefore, it is required to be able to efficiently remove the remaining tungsten or cobalt by CMP, and to 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

[Problem to be solved by the invention] With the popularization of semiconductor wafers containing conductive metals such as tungsten and cobalt, there is a demand for a chemical mechanical polishing composition and a chemical mechanical polishing method that can polish a polishing surface where conductive metals such as tungsten and cobalt coexist with an insulating film such as a silicon oxide film at high speed and flatly, and can reduce surface defects after polishing.

In particular, on a polished surface where a conductive metal and an insulating film coexist, when the polishing speed of the conductive metal is faster than that of the insulating film, a surface defect called dishing, in which the conductive metal portion is shaved into a dish shape, is likely to occur, and a solution to this problem is required. [Means for Solving the Problem]

One form of the chemical mechanical polishing composition of the present invention comprises: (A) silicon dioxide particles modified with a compound having two or more amine groups; and (B) a liquid medium.

In one form of the chemical mechanical polishing composition, the zeta potential of the component (A) in the chemical mechanical polishing composition is greater than +10 mV.

In any form of the chemical mechanical polishing composition, it can be: When the total mass of the chemical mechanical polishing composition is set to 100 mass %, the content of the component (A) is greater than 0.1 mass % and less than 10 mass %.

In any form of the chemical mechanical polishing composition, an acidic compound may be further contained.

In any form of the chemical mechanical polishing composition, an oxidizing agent may be further contained.

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

One form of the chemical mechanical polishing method of the present invention includes: The step of polishing a semiconductor substrate using any form of the chemical mechanical polishing composition.

In one form of the chemical mechanical polishing method, the semiconductor substrate may include 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 surface defects after polishing can be reduced.

The following describes in detail the preferred 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, a numerical range described using "～" means that the numerical values described before and after the "～" are included as the lower limit and upper limit.

1. Chemical mechanical polishing composition The chemical mechanical polishing composition of one embodiment of the present invention comprises: (A) silicon dioxide particles modified with a compound having two or more amino groups (also referred to as "(A) component" in this specification), and (B) a liquid medium (also referred to as "(B) component" in this specification). The following is a detailed description of each component contained in the chemical mechanical polishing composition of this embodiment.

1.1. (A) Component The chemical mechanical polishing composition of this embodiment contains (A) silicon dioxide particles modified with a compound having two or more amine groups as an abrasive component. When the pH of the chemical mechanical polishing composition is between 1 and 6, the (A) component has a relatively large positive charge due to the amine group. Therefore, insulating films such as silicon oxide films whose surface potential changes from 0 to negative in the region where the pH is between 1 and 6 can be polished at a higher speed. In this way, the polishing surface where the insulating film and the conductive metal coexist can be polished at a high speed and flatly, and the generation of depressions in the conductive metal portion can be suppressed.

Furthermore, as the number of amine groups in the "compound having two or more amine groups" that modifies the silica particles increases, the absolute value of the zeta potential of the component (A) increases, and the difference between the polishing rate of the insulating film and the polishing rate of the conductive metal tends to decrease. As a result, the flatness of the polished surface where the insulating film and the conductive metal coexist may be improved.

The component (A) is a silica particle having a compound having two or more functional groups selected from the group consisting of amine groups and salts thereof fixed to the surface via covalent bonds, and does not include silica particles having the compound physically or ionically adsorbed on the surface.

As the compound having two or more amino groups, for example, a compound represented by the following general formula (1) can be preferably used.

SiR ¹ _m (OR ² ) _n (R ³ -NR ⁴ ₂ ) _p・・・・・（1）

In the above formula (1), R ¹ and R ² each independently represent a monovalent hydrocarbon group. The monovalent hydrocarbon group is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, and tert-butyl. Examples of the aryl group having 6 to 12 carbon atoms include phenyl and naphthyl.

In the above formula (1), R ³ represents a divalent alkyl group. Examples of the divalent alkyl group include a linear or branched divalent alkyl group having 1 to 10 carbon atoms. Among them, an alkanediyl group having 1 to 3 carbon atoms is preferred. Examples of the linear or branched divalent alkyl group having 1 to 10 carbon atoms include a methylene group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group.

In the above formula (1), ^R4 independently represents a monovalent organic group having 1 to 10 carbon atoms which may contain a heteroatom or a hydrogen atom. Examples of the monovalent organic group having 1 to 10 carbon atoms which may contain a heteroatom include a linear or branched monovalent alkyl group having 1 to 10 carbon atoms. Examples of the linear or branched monovalent alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. Furthermore, when ^R4 is an alkyl group, an alkenyl group, or a phenyl group, a part of the hydrogen atoms thereof may be substituted by an amino group, a sulfonic group, a halogen atom, or the like.

In the formula (1), m is an integer from 0 to 2, n is an integer from 0 to 2, p is an integer from 2 to 4, and m+n+p=4.

Specific examples of the compound having two or more amino groups include (aminoethyl)aminopropyltrimethoxysilane, N-(3-trimethoxysilylpropyl)ethylenediamine, N-(3-triethoxysilylpropyl)ethylenediamine, N-(3-tripropoxysilylpropyl)ethylenediamine, N-[2-[3-(triethoxysilyl)propylamino]ethyl]ethylenediamine, N-[2-[3-(tripropoxysilyl)propylamino]ethyl]ethylenediamine, N-[2-[3-(triisopropoxysilyl)propylamino]ethyl]ethylenediamine, and N-[2-[3-(trimethoxysilyl)propylamino]ethyl]ethylenediamine.

The component (A) used in the present embodiment can be produced, for example, as follows. First, prepare silica particles. As silica particles, for example, fumed silica, colloidal silica, etc. can be listed, but from the perspective of reducing polishing defects such as scratches, colloidal silica is preferred. Colloidal silica can be produced, for example, by the method described in Japanese Patent Publication No. 2003-109921. By modifying the surface of such silica particles with a compound having two or more amine groups, the component (A) that can be used in the present embodiment can be produced. The following is an example of a method for modifying the surface of silica particles with a compound having two or more amine groups, but the present invention is not limited to this specific example.

As the surface modification of silica particles, the method described in Japanese Patent Publication No. 2005-162533 or Japanese Patent Publication No. 2010-269985 can be applied. For example, by mixing silica particles with a silane coupling agent having two or more amine groups (e.g., (aminoethyl)aminopropyltrimethoxysilane) and stirring them sufficiently, the silane coupling agent having two or more amine groups can be covalently bonded to the surface of the silica particles. By further heating and hydrolyzing, silica particles with two or more amine groups fixed via covalent bonds can be obtained.

The lower limit of the average particle size of the component (A) is preferably 15 nm, more preferably 30 nm. The upper limit of the average particle size of the component (A) is preferably 100 nm, more preferably 70 nm. If the average particle size of the component (A) is within the above range, it is possible to suppress the occurrence of polishing defects and polish the polished surface where a conductive metal such as tungsten and cobalt and an insulating film such as a silicon oxide film coexist at a practical polishing rate. The average particle size of the component (A) can be obtained by measuring the manufactured chemical mechanical polishing composition using a particle size measuring device using a dynamic light scattering method. Examples of particle size measurement devices based on the dynamic light scattering method include the nanoparticle analyzer "DelsaNano S" manufactured by Beckman-Coulter and the "Zetasizer Nano ZS" manufactured by Malvern. The average particle size measured using the dynamic light scattering method represents the average particle size of secondary particles formed by the aggregation of multiple primary particles.

When the pH of the chemical mechanical polishing composition is 1 or more and 6 or less, the zeta potential of the component (A) is positive in the chemical mechanical polishing composition, and the lower limit of the positive potential is preferably +10 mV, more preferably +15 mV. In addition, the upper limit of the positive potential is preferably +40 mV, more preferably +35 mV. If the zeta potential of the component (A) is within the above range, the electrostatic repulsion between the particles can sometimes effectively prevent the aggregation of the particles, and at the same time, an insulating film such as a silicon oxide film that is negatively charged from 0 can be polished at a high speed during chemical mechanical polishing. In addition, as a zeta potential measuring device, there can be mentioned "ELSZ-1" manufactured by Otsuka Electronics Co., Ltd., "Zetasizer nano zs" manufactured by Malvern, etc. The zeta potential of the component (A) can be appropriately adjusted by increasing or decreasing the amount of the silane coupling agent having two or more amino groups added.

When the total mass of the chemical mechanical polishing composition is set to 100 mass%, the lower limit of the content of component (A) 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 component (A) is preferably 10 mass%, more preferably 8 mass%, and particularly preferably 5 mass%. When the content of component (A) is within the above range, it is possible to polish a surface to be polished where a conductive metal such as tungsten or cobalt and an insulating film such as a silicon oxide film coexist at a practical polishing rate while suppressing the occurrence of polishing defects.

1.2. (B) Liquid medium The chemical mechanical polishing composition of this embodiment contains (B) liquid medium. As the (B) component, water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent having compatibility with water, etc. can be listed. Among these, it is preferred to use water or a mixed medium of water and alcohol, and it is more preferred to use water. There is no particular limitation on the water, but pure water is preferred. Water can be prepared as the remainder of the constituent materials of the chemical mechanical polishing composition, and there is no particular limitation on the water content.

1.3. Other additives The chemical mechanical polishing composition of this embodiment may contain additives such as oxidizing agents, 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 or cobalt are oxidized to promote complex reactions with polishing liquid components, thereby forming 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, ammonium nitrate, potassium hypochlorite, ozone, potassium periodate, peracetic acid, etc. 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 0.1 mass % to 5 mass %, more preferably 0.3 mass % to 4 mass %, and particularly preferably 0.5 mass % to 3 mass %, based on the total mass of the chemical mechanical polishing composition as 100 mass %. Furthermore, the oxidizing agent is easily decomposed in the chemical mechanical polishing composition, and therefore, it is ideally added just before the CMP polishing step.

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

Examples of such acidic compounds include organic acids and inorganic acids. Examples of organic acids include saturated carboxylic acids such as 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 1,2,4-tricarboxylic 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, 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 %, based on the total mass of the chemical mechanical polishing composition as 100 mass %.

<Surfactant> The chemical mechanical polishing composition of this embodiment may also contain a surfactant. By containing a surfactant, there is a case where the chemical mechanical polishing composition can be given a moderate viscosity. 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, and nonionic surfactants.

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 %, based on the total mass of the chemical mechanical polishing composition as 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. This effect can reduce the occurrence of polishing defects on the polished surface.

Examples of the water-soluble polymer include polyethyleneimine, poly(meth)acrylamine, poly(meth)acrylamide, poly(meth)acrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, and copolymers of (meth)acrylic acid and maleic acid.

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 wiring material, etc., and the polishing friction can be further reduced. As a result, the generation of polishing defects on 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 %, more preferably 0.03 mass % to 0.5 mass %, based on the total mass of the chemical mechanical polishing composition as 100 mass %.

Furthermore, the content of the water-soluble polymer also depends on the weight average molecular weight (Mw) of the water-soluble polymer, but it 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. When 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 wiring materials at high speed, and the viscosity is appropriate, so the chemical mechanical polishing composition can be stably supplied to the polishing cloth.

<Anti-corrosion agent> The chemical mechanical polishing composition of this embodiment may also contain an anti-corrosion agent. Examples of the anti-corrosion agent include benzotriazole and its derivatives. Here, the benzotriazole derivative refers to a substance in which one or more hydrogen atoms of benzotriazole are replaced by, for example, a carboxyl group, a methyl group, an amino group, a hydroxyl group, etc. Specific examples of benzotriazole derivatives include 4-carboxybenzotriazole, 7-carboxybenzotriazole, benzotriazole butyl ester, 1-hydroxymethylbenzotriazole, 1-hydroxybenzotriazole, and salts thereof.

When the chemical mechanical polishing composition of the present 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 one or more of these may be used.

1.5. pH The pH of the chemical mechanical polishing composition of the present embodiment is not particularly limited, but is preferably 2 or more and 5 or less, and more preferably 2 or more and 4 or less. If the pH is within the above range, the dispersibility of the component (A) 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, the pH adjuster, etc.

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

1.6. Application The chemical mechanical polishing composition of the present embodiment is suitable as a polishing material for chemical mechanical polishing of a semiconductor substrate having multiple materials constituting a semiconductor device. For example, the semiconductor substrate may include insulating film materials such as silicon oxide film, silicon nitride film, amorphous silicon, and barrier metal materials such as titanium, titanium nitride, and tantalum nitride in addition to conductive metals 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 for the polishing surface where the tungsten film and an insulating film such as a silicon oxide film coexist, it is possible to perform high-speed and flat polishing while suppressing the occurrence of polishing defects.

1.7. 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 into a concentrated stock solution, which can be diluted with a liquid medium such as water before use.

2. Chemical Mechanical Polishing Method The polishing method according to one 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 of this embodiment is described in detail below using a diagram.

2.1. Object to be processed Figure 1 is a schematic cross-sectional view of an object to be processed that is suitable for the chemical mechanical polishing method of the present embodiment. The object to be processed 100 is formed by the following steps (1) to (4).

(1) First, as shown in FIG. 1 , a substrate 10 is prepared. The substrate 10 may be composed of, for example, a silicon substrate and a silicon oxide film formed thereon. Furthermore, functional elements such as transistors (not shown) may be formed on the substrate 10. Next, a silicon oxide film 12 is formed on the substrate 10 as an insulating film 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 Figure 2 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 Figure 2, the chemical mechanical polishing composition is used to polish the tungsten film 18 until the barrier metal film 16 is exposed.

2.2.2. Second polishing step Figure 3 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 Figure 3, 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 with 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 multiple 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 shown in FIG. 4 can be used. FIG. 4 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 cloth 46 attached thereto is rotated while a carrier head 52 holding a semiconductor substrate 50 is brought into contact. Furthermore, in FIG. 4, 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 the models "EPO-112" and "EPO-222" manufactured by Ebara Manufacturing Co., Ltd.; the models "LGP-510" and "LGP-552" manufactured by Lapmaster SFT; the models "Mirra" and "Reflexion" manufactured by Applied Material; the model "POLI-400L" manufactured by G&P TECHNOLOGY; and the model "Reflexion LK" manufactured by AMAT.

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

3.1. Preparation of aqueous dispersion of silica particles 3.1.1. Preparation of aqueous dispersion A A mixture of 1522.2 g of tetramethoxysilane and 413.0 g of methanol was added dropwise to a mixture of 787.9 g of pure water, 786.0 g of 26% ammonia water, and 12924 g of methanol while maintaining the liquid temperature at 35°C for 55 minutes to obtain a hydrolyzed silica sol dispersion. The sol was heated and concentrated to 2900 ml at normal pressure. The concentrated solution was further heated and distilled at normal pressure, and pure water was added dropwise while maintaining the volume constant. When it was confirmed that the top temperature reached 100°C and the pH was 8 or less, the addition of pure water was stopped to obtain aqueous dispersion A.

3.1.2. Preparation of aqueous dispersion B A mixture of 19.0 g of methanol and 1.0 g of N-(3-trimethoxysilylpropyl)ethylenediamine was added dropwise to 540 g of aqueous dispersion A over 10 minutes while maintaining the liquid temperature, and then refluxed at normal pressure for 2 hours. Then, pure water was added dropwise while maintaining the volume constant, and the addition of pure water was terminated when the tower top temperature reached 100°C, to obtain aqueous dispersion B containing silica particles modified with a compound having two amino groups.

3.1.3. Preparation of aqueous dispersion C Except for using N-[2-[3-(trimethoxysilyl)propylamino]ethyl]ethylenediamine instead of N-(3-trimethoxysilylpropyl)ethylenediamine, aqueous dispersion C containing silica particles modified with a compound having three amine groups was obtained in the same manner as in [3.1.2. Preparation of aqueous dispersion B].

3.1.4. Preparation of aqueous dispersion D In the same manner as in [3.1.2. Preparation of aqueous dispersion B], aqueous dispersion D containing silica particles modified with a compound having one amine group was obtained, except that 3-aminopropyltriethoxysilane was used instead of N-(3-trimethoxysilylpropyl)ethylenediamine.

3.2. Preparation of chemical mechanical polishing composition Hydrogen peroxide (manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Hydrogen Peroxide (30% aqueous solution)") was used as an oxidizing agent, and each component was added to a polyethylene container so as to have the composition shown in Tables 1 to 3. Potassium hydroxide was added as needed and the pH was adjusted so as to have the pH shown in Tables 1 to 3. The chemical mechanical polishing composition of each Example and each Comparative Example was prepared by adjusting with pure water so that the total amount of all the components was 100 parts by mass.

For each chemical mechanical polishing composition obtained in this way, the average particle size of the abrasive particles was measured using a particle size measuring device (manufactured by Malvern, model "Zetasizer nano zs"), and the results are shown in Tables 1 to 3.

For each chemical mechanical polishing composition obtained in this way, the zeta potential of the abrasive grains was measured using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model "DT300"), and the results are shown in Tables 1 to 3.

3.3. Evaluation method 3.3.1. Polishing rate test Using the chemical mechanical polishing composition obtained above, a 12-inch diameter wafer with a 300 nm CVD-W film or a 12-inch diameter wafer with a 300 nm p-TEOS film (silicon oxide 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 Co., Ltd., "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 tungsten film was measured by using a resistivity meter (manufactured by KLA-Tencor, model "OmniMap RS100") and a DC four-probe method to measure the resistance. 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) ÷ surface resistance value (Ω)] × 10 ¹⁰

The evaluation criteria for the polishing speed test are as follows. The polishing speed results of the tungsten film, the polishing speed results of the silicon oxide film, and their evaluation results are shown together in Tables 1 to 3. (Evaluation criteria) • "A"... When the ratio of the tungsten polishing speed to the p-TEOS polishing speed is greater than 0.1 and less than 1.0, it is easy to ensure the speed balance of both polishing films in actual semiconductor polishing and is practical, so it is judged as good "A". • "B"... When the ratio of the tungsten polishing speed to the p-TEOS polishing speed is greater than 1.0, it is difficult to ensure the speed balance of both polishing films in actual semiconductor polishing, so it is difficult to be practical, and it is judged as bad "B".

3.3.2. Flatness evaluation The following test substrate was used: a 12-inch wafer with a 100 nm silicon oxide film formed thereon was processed into a "SEMATECH 754" pattern with a depth of 100 nm, a 10 nm TiN film was deposited, and then a 200 nm tungsten film was deposited (manufactured by SEMATECH INTERNATIONAL).

The test substrate was polished under the following conditions until the silicon oxide film was exposed. The polished surface was examined using a stylus profiling system (manufactured by BRUKER, model "Dektak XTL") to check the step difference (tungsten depression) of the tungsten/silicon oxide film wiring in the pattern portion where the tungsten wiring width (line, L)/silicon oxide film wiring width (space, S) was 0.18 μm/0.18 μm, respectively. The evaluation criteria are as follows. The values of the tungsten depression and the evaluation results are shown together in Tables 1 to 3. (Evaluation criteria) • "A" ... When the tungsten depression is less than 2 nm, it can be judged as very good. • "B" ... When the tungsten depression is 2 nm or more and less than 9 nm, it is judged as good. • "C" ... When the tungsten depression is 9 nm or more, it is judged as bad.

3.4. Evaluation results Tables 1 to 3 below show the composition of the chemical mechanical polishing composition of each embodiment and each comparative example and the evaluation results.

[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 Abrasive particles Type Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Compounds for surface modification Diamine Diamine Diamine Diamine Diamine Diamine Diamine Diamine Diamine Diamine Average particle size (nm) 66 66 66 66 66 66 66 66 66 66 Zeta potential (mV) 18 18 18 18 18 18 18 18 18 18 Content (mass %) 2.0 1.0 3.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Additives Type Citric Acid Citric Acid Citric Acid Maleic acid Malonate Nitric Acid Citric Acid Citric Acid Citric Acid Citric Acid Content (mass %) 0.1 0.1 0.1 0.03 0.06 0.007 0.1 0.1 0.1 0.1 Type esleam AD-3172M esleam AD-3172M esleam AD-3172M Content (mass %) 0.01 0.05 0.1 Oxidants Type Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Content (mass %) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.5 pH 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Evaluation items Grinding speed Tungsten film polishing speed (Å/min) 354 230 370 340 325 290 300 278 265 297 Silicon oxide film polishing speed (Å/min) 413 270 445 412 416 345 383 403 415 397 Tungsten film polishing speed/Silicon oxide film polishing speed 0.86 0.85 0.83 0.83 0.78 0.84 0.78 0.69 0.64 0.75 Evaluation results A A A A A A A A A A Flatness evaluation Tungsten depression (nm) 5.0 5.2 3.6 3.4 3.6 4.2 2.8 1.8 1.2 2.8 Evaluation results B B B B B B B A A B

[Table 2] Embodiment 11 Embodiment 12 Embodiment 13 Embodiment 14 Embodiment 15 Embodiment 16 Embodiment 17 Embodiment 18 Embodiment 19 Embodiment 20 Compositions for chemical mechanical polishing Abrasive particles Type Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion B Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Compounds for surface modification Diamine Diamine Diamine Diamine Triamine Triamine Triamine Triamine Triamine Triamine Average particle size (nm) 66 66 66 66 67 67 67 67 67 67 Zeta potential (mV) 18 18 18 18 20 20 20 20 20 20 Content (mass %) 2.0 2.0 2.0 2.0 2.0 1.0 3.0 2.0 2.0 2.0 Additives Type Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Maleic acid Malonate Nitric Acid Content (mass %) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.03 0.08 0.007 Type NISSAN ANON LA Content (mass %) 0.005 Oxidants Type Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Content (mass %) 2.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 pH 3.0 2.1 4.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Evaluation items Grinding speed Tungsten film polishing speed (Å/min) 378 287 360 280 360 243 378 345 354 300 Silicon oxide film polishing speed (Å/min) 415 354 413 398 423 285 456 423 432 356 Tungsten film polishing speed/Silicon oxide film polishing speed 0.91 0.81 0.87 0.70 0.85 0.85 0.83 0.82 0.82 0.84 Evaluation results A A A A A A A A A A Flatness evaluation Tungsten depression (nm) 8.4 3.8 4.5 3.6 5.0 7.8 3.6 3.4 3.6 4.2 Evaluation results B B B B B B B B B B

[table 3] Embodiment 21 Embodiment 22 Embodiment 23 Embodiment 24 Embodiment 25 Embodiment 26 Embodiment 27 Embodiment 28 Comparison Example 1 Comparison Example 2 Compositions for chemical mechanical polishing Abrasive particles Type Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion C Aqueous Dispersion A Aqueous dispersion D Compounds for surface modification Triamine Triamine Triamine Triamine Triamine Triamine Triamine Triamine without Monoamine Average particle size (nm) 67 67 67 67 67 67 67 67 65 65 Zeta potential (mV) 20 20 20 20 20 20 20 20 3 10 Content (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Additives Type Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Citric Acid Content (mass %) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.05 0.075 Type esleam AD-3172M esleam AD-3172M esleam AD-3172M NISSAN ANON LA Content (mass %) 0.01 0.05 0.1 0.005 Oxidants Type Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide Content (mass %) 1.0 1.0 1.0 0.5 2.0 1.0 1.0 1.0 1.0 1.0 pH 3.0 3.0 3.0 3.0 3.0 2.1 4.0 3.0 3.0 3.0 Evaluation items Grinding speed Tungsten film polishing speed (Å/min) 311 290 270 298 402 289 402 310 286 331 Silicon oxide film polishing speed (Å/min) 396 418 430 411 419 367 432 412 271 327 Tungsten film polishing speed/Silicon oxide film polishing speed 0.79 0.69 0.63 0.73 0.96 0.79 0.93 0.75 1.06 1.01 Evaluation results A A A A A A A A B B Flatness evaluation Tungsten depression (nm) 2.8 1.8 1.2 2.8 8.3 3.8 8.2 3.6 9.2 9.4 Evaluation results B A A B B B B B C C

The following products or reagents were used for each component in Tables 1 to 3. The content of abrasive grains in Tables 1 to 3 indicates the solid content concentration of each aqueous dispersion. ＜Abrasive grains＞ • Aqueous dispersion A to aqueous dispersion D: Aqueous dispersion A to aqueous dispersion D of the prepared silica particles <Compounds for surface modification＞ • Monoamine: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "(3-Aminopropyltriethoxysilane)", 3-aminopropyltriethoxysilane • Diamine: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "3-(2-aminoethylamino)propyltrimethoxysilane (3-(2- =Triamine: manufactured by Fuji Film Co., Ltd. Wako Pure Chemical Industries, Ltd., trade name "Trimethoxysilylpropyl diethylenetriamine", N-[2-[3-(Trimethoxysilyl)propylamino]ethyl]ethylenediamine <Acidic compounds> •Citric acid: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Citric acid (Citric acid) Acid) •Maleic acid: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Maleic Acid" •Malonic acid: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Malonic Acid" •Nitric acid: manufactured by Kanto Chemical Co., Ltd., trade name "Nitric Acid 1.38" <Water-soluble polymer> •esleam AD-3172M: manufactured by NOF Corporation, trade name "esleam AD-3172M" <Surfactant> •NISSAN ANON LA: manufactured by NOF Corporation, trade name "NISSAN ANON" LA, sodium lauryl aminodiacetate <Oxidant> •Hydrogen peroxide: manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Hydrogen Peroxide (35% aqueous solution) (35% in Water

According to the evaluation results in Tables 1 to 3 above, when the chemical mechanical polishing compositions of Examples 1 to 28 are used, tungsten films and p-TEOS films can be polished at practical polishing speeds, and the polishing speed balance of both films can be easily ensured, and surface defects (tungsten pits) after polishing can be significantly reduced.

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes a configuration substantially the same as the configuration described in the embodiments (e.g., a configuration having the same function, method, and result, or a configuration having the same purpose and effect). In addition, the present invention includes a configuration in which the non-essential part of the configuration described in the embodiments is replaced. In addition, the present invention includes a configuration that exerts the same effect as the configuration described in the embodiments, or a configuration that can achieve the same purpose. In addition, the present invention includes a configuration obtained by adding a known technology to the configuration described in the embodiments.

10: substrate 12: silicon oxide film 14: through hole 16: barrier metal film 18: tungsten film 42: slurry supply nozzle 44: chemical mechanical polishing composition (slurry) 46: polishing cloth 48: turntable 50: semiconductor substrate 52: carrier head 54: water supply nozzle 56: dresser 100: processed object 200: semiconductor device 300: chemical mechanical polishing device

FIG1 is a schematic cross-sectional view of a workpiece used in chemical mechanical polishing according to the present embodiment. FIG2 is a schematic cross-sectional view of a workpiece after a first polishing step. FIG3 is a schematic cross-sectional view of a workpiece after a second polishing step. FIG4 is a schematic perspective view of a chemical mechanical polishing apparatus.

Claims (7)

A chemical mechanical polishing composition comprises: (A) component: silicon dioxide particles modified with a compound having two or more amine groups; and (B) a liquid medium, wherein the zeta potential of the (A) component is greater than +10 mV, and the (B) liquid medium is water. The chemical mechanical polishing composition as described in claim 1, wherein when the total mass of the chemical mechanical polishing composition is set to 100 mass%, the content of the component (A) is greater than 0.1 mass% and less than 10 mass%. The chemical mechanical polishing composition as described in claim 1 further contains an acidic compound. The chemical mechanical polishing composition as described in claim 1 further contains an oxidizing agent. The chemical mechanical polishing composition as described in claim 1, wherein the pH is greater than 2 and less than 5. A chemical mechanical polishing method, comprising the step of polishing a semiconductor substrate using a chemical mechanical polishing composition as described in any one of claim 1 to claim 5. A chemical mechanical polishing method as described in claim 6, wherein the semiconductor substrate includes a portion containing at least one selected from the group consisting of silicon oxide and tungsten.

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