TWI814885B - Chemical mechanical polishing aqueous dispersion and manufacturing method thereof - Google Patents

Abstract

The present invention provides a chemical mechanical polishing aqueous dispersion that can suppress over-etching of a polished surface containing wiring metal materials and barrier metal materials, polish the polished surface at high speed, and has excellent stability. One aspect of the chemical mechanical polishing aqueous dispersion of the present invention contains: (A) abrasive particles, (B) iron salts, and (C) selected from the group consisting of compounds having hydroxyl groups and carboxyl groups and salts thereof At least one type, and the pH is between 7 and 14.

Description

Chemical mechanical polishing aqueous dispersion and manufacturing method thereof

The invention relates to a chemical mechanical grinding aqueous dispersion and a manufacturing method thereof.

Chemical Mechanical Polishing (CMP) is rapidly spreading as a planarization technology in the manufacture of semiconductor devices. In this CMP, the object to be polished is pressed against the polishing pad, and a chemical mechanical polishing aqueous dispersion is supplied to the polishing pad while the object to be polished and the polishing pad slide against each other, thereby chemically and mechanically polishing the object to be polished. Technology.

In recent years, as semiconductor devices have become more sophisticated, wiring layers including wiring, plugs, and the like formed in the semiconductor device have been miniaturized. Along with this, a method of planarizing the wiring layer by CMP is used. The substrate of the semiconductor device includes an insulating film material, a wiring metal material, a barrier metal material for preventing the wiring metal material from diffusing into the inorganic material film, and the like. Here, silicon dioxide is mainly used as the insulating film material, copper or tungsten is mainly used as the wiring metal material, and tantalum nitride or titanium nitride is mainly used as the barrier metal material.

Among the substrate materials in these semiconductor devices, tungsten, which is a wiring metal material, has relatively high hardness and is not easily affected by chemicals. Therefore, in tungsten CMP slurry, it is important to passivate the tungsten surface by an oxidant to form oxides. The oxide layer can be removed by mechanical polishing using abrasives or the like. As such a tungsten CMP slurry, for example, a technique has been proposed in which ferric nitrate and hydrogen peroxide are used in combination in order to generate a strong oxidation reaction (see, for example, Patent Document 1).

[Prior art documents]

[Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2012-74734

In the tungsten CMP slurry described in Patent Document 1, it is recommended to adjust the pH to an acidic region. The reason for this is presumed to be that the stability of the added components can be improved at a pH in the acidic region, and the abrasive particles can easily come into contact with tungsten through electrostatic interaction, thereby enabling high-speed polishing of tungsten. In addition, the reason is that in an alkaline region, when the slurry contains iron salts such as iron nitrate, the following disadvantages may occur: precipitates such as iron hydroxide are generated and stability is easily impaired, so that sufficient Grinding characteristics.

However, in CMP of a substrate in a semiconductor device, there are cases where it is required to polish not only tungsten as a wiring metal material but also a barrier metal used for the purpose of improving wiring reliability in one step. When grinding an object containing these materials in one step, it is considered that when the pH of the slurry is in an alkaline range, the dispersion stability of the abrasive particles (especially silica) is improved, and therefore high-speed grinding is possible. Surface to be ground.

Therefore, some aspects of the present invention provide a chemical mechanical polishing aqueous dispersion that can suppress over-etching of a polished surface containing a wiring metal material and a barrier metal material, and polish the polished surface at a high speed, thereby further Stability is also excellent. In addition, some aspects of the present invention provide a method for manufacturing the chemical mechanical polishing aqueous dispersion.

This invention is made in order to solve at least a part of the said subject, and can be implemented as any of the following aspects.

One aspect of the chemical mechanical polishing aqueous dispersion of the present invention contains: (A) abrasive particles; (B) iron salts; and (C) selected from the group consisting of compounds having hydroxyl groups and carboxyl groups and salts thereof At least one type, and the pH is between 7 and 14.

In one aspect of the chemical mechanical polishing aqueous dispersion, the component (C) may contain at least one selected from the group consisting of compounds having a hydroxyl group, a carboxyl group, and an amine structure, and salts thereof.

In any aspect of the chemical mechanical polishing aqueous dispersion, the component (C) may contain a polycarboxylic acid selected from the group consisting of a hydroxyl group and two or more amine structures and a salt thereof. At least one.

In any aspect of the chemical mechanical polishing aqueous dispersion, the component (C) may contain a component selected from the group consisting of N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid. ,N,N- At least one of the group consisting of bis(2-hydroxyethyl)glycine and N,N'-ethylidenebis[N-(2-hydroxybenzyl)glycine].

In any aspect of the chemical mechanical polishing aqueous dispersion, the iron salt (B) may contain at least one selected from the group consisting of iron nitrate and iron sulfate.

In any aspect of the chemical mechanical polishing aqueous dispersion, let the content of the component (C) be M _C (mol), and let the content of the component (B) be _MB (mol). ), the molar ratio M _C / _MB may be 0.3 or more and 3.0 or less.

Any aspect of the chemical mechanical polishing aqueous dispersion may further contain (D) at least one selected from the group consisting of organic acids and salts thereof (excluding the component (C)).

In any aspect of the chemical mechanical polishing aqueous dispersion, (E) may further contain at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

Any aspect of the chemical mechanical polishing aqueous dispersion can be used for polishing a substrate containing at least one selected from the group consisting of tungsten, copper, cobalt, titanium, ruthenium, titanium nitride, and tantalum nitride. .

One aspect of the method for producing a chemical mechanical polishing aqueous dispersion of the present invention includes: a first step of dispersing or dissolving (A) abrasive grains, (B) iron salts, and (C) compounds having hydroxyl groups and carboxyl groups in the water system medium to obtain an aqueous dispersion; and a second step using (E) selected from the group consisting of sodium hydroxide, potassium hydroxide and hydroxide. At least one kind from the group consisting of ammonium adjusts the pH of the aqueous dispersion to 7 or more and 14 or less.

According to the chemical mechanical polishing aqueous dispersion of the present invention, wiring metal materials and barrier metal materials can be polished at high speed while suppressing excessive etching of these materials. In addition, according to the chemical mechanical polishing aqueous dispersion of the present invention, the generation of precipitates derived from the (B) iron salt can be suppressed even at a pH in the alkaline range, and the stability is improved, thereby improving the polishing characteristics.

42: Slurry supply nozzle

44: Slurry (aqueous dispersion for chemical mechanical grinding)

46:Abrasive cloth

48:Turntable

50:Substrate

52: Carrying head

54:Water supply nozzle

56: Dresser

100:Grinding device

FIG. 1 is a perspective view schematically showing a chemical mechanical polishing apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, the present invention is not limited to the following embodiments, but also includes various modifications implemented within the scope that does not change the gist of the present invention.

In this manual, the numerical range written with "~" means that the numerical range written before and after "~" is included as the lower limit value and the upper limit value.

In this specification, the "acidic region" refers to a region with a pH of less than 7, and the "alkaline region" refers to a region with a pH of 7 or more.

The so-called "wiring metal materials" refer to conductive metal materials such as aluminum, copper, cobalt, titanium, ruthenium, and tungsten. The so-called "insulating film material" refers to materials such as silicon dioxide, silicon nitride, and amorphous silicon. The so-called "barrier metal materials" refer to tantalum nitride, titanium nitride, etc. A material that is laminated with wiring metal materials for the purpose of improving wiring reliability.

1. Chemical mechanical polishing aqueous dispersion

The chemical mechanical polishing aqueous dispersion of this embodiment contains: (A) abrasive grains (hereinafter, also referred to as "(A) component"); (B) iron salt (hereinafter, also referred to as "(B) component") ; and (C) at least one selected from the group consisting of compounds having hydroxyl groups and carboxyl groups and salts thereof (hereinafter, also referred to as "(C) component"), and the pH is 7 or more and 14 or less. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion of this embodiment will be described in detail.

1.1.(A)Abrasive grains

The chemical mechanical polishing aqueous dispersion of this embodiment contains (A) abrasive grains. (A) The abrasive grains have the function of mechanically polishing wiring metal materials and barrier metal materials that are polishing targets, and increasing the polishing speed of these materials. (A) The abrasive grains are not particularly limited, and examples thereof include inorganic particles such as silica, cerium oxide, aluminum oxide, zirconium oxide, and titanium oxide. Among these, silica, aluminum oxide, and titanium oxide are preferred, and silica is more preferred. The reason is that silicon dioxide in particular is easily negatively charged at a pH in an alkaline region, so the dispersion stability is improved by electrostatic repulsion. (A) Abrasive grains may be used individually by 1 type, or in combination of 2 or more types at any ratio.

Examples of silica include fumed silica, colloidal silica, and the like, and colloidal silica is preferred. As colloidal silica, for example, one produced by the method described in Japanese Patent Application Laid-Open No. 2003-109921 or the like can be used.

The average particle diameter of (A) the abrasive grains is not particularly limited, and its lower limit is 5nm is preferred, 10nm is more preferred, and 15nm is particularly preferred. The upper limit is preferably 300nm, 150nm is more preferred, and 100nm is particularly preferred. If the average particle diameter of (A) the abrasive grains is within the above range, the polishing speed of the wiring metal material and the barrier metal material can be increased while the occurrence of polishing damage on the polished surface can be reduced. Within the above range, if the average particle diameter of (A) the abrasive grains is 150 nm or less as the upper limit, the polishing speed of the wiring metal material and the barrier metal material may be further increased. In addition, if the average particle diameter of (A) the abrasive grains is the lower limit of 10 nm or more, the occurrence of polishing damage in the surface to be polished may be further reduced.

(A) The average particle diameter of the abrasive grains can be determined by measuring using a particle size distribution measuring device based on the dynamic light scattering method as the measurement principle. Examples of particle size measuring devices using the dynamic light scattering method include the dynamic light scattering particle size distribution measuring device "LB-550" manufactured by Horiba Manufacturing Co., Ltd., and the NANO manufactured by Beckman-Coulter. Nanoparticle analyzer "DelsaNanoS", "Zetasizernanozs" manufactured by Malvern, etc. In addition, the average particle diameter measured using the dynamic light scattering method indicates the average particle diameter of secondary particles formed by aggregation of a plurality of primary particles.

The lower limit of the content of (A) abrasive grains relative to the total mass of the chemical mechanical polishing aqueous dispersion is preferably 0.05 mass%, more preferably 0.1 mass%, and particularly preferably 0.3 mass%. If the content of the abrasive grains (A) is equal to or higher than the lower limit, a sufficient polishing rate for polishing the wiring metal material and the barrier metal material may be obtained. On the other hand, the upper limit of the content of (A) abrasive grains is preferably 10% by mass, more preferably 5% by mass, relative to the total mass of the chemical mechanical polishing aqueous dispersion. Particularly optimal is 3% by mass. When the content of (A) abrasive grains is below the upper limit, storage stability tends to be good, and good flatness of the surface to be polished or reduction in polishing damage may be achieved.

1.2.(B)Iron salt

The chemical mechanical polishing aqueous dispersion of this embodiment contains (B) iron salt. Since the chemical mechanical polishing aqueous dispersion of this embodiment contains the iron salt (B), the surface of the wiring metal material or barrier metal material can be passivated and an oxide layer can be formed. Furthermore, the oxide layer can be removed at high speed by the mechanical polishing action of (A) abrasive grains. Among wiring metal materials or barrier metal materials, it is easy to increase the polishing speed of materials containing at least any one of tungsten, cobalt and titanium nitride, and it is even easier to increase the polishing speed of materials containing at least any one of tungsten and titanium nitride. speed.

Furthermore, the (B) iron salt in the aqueous dispersion includes not only those that form iron salts, but also those that are ionized and ionized (iron ions).

Specific examples of the iron salt (B) include iron nitrate, iron sulfate, iron ammonium sulfate, iron perchlorate, iron chloride, iron citrate, iron ammonium citrate, iron oxalate, and iron ammonium oxalate. Among these, at least one selected from the group consisting of iron nitrate and iron sulfate is preferred, and iron nitrate is more preferred. In particular, ferric nitrate easily dissociates into iron ions in an aqueous dispersion, and causes a strong oxidation reaction (Fenton reaction) when used in combination with hydrogen peroxide, which will be described later. Therefore, tungsten, which is a wiring metal material, can be polished at high speed. wait. (B) Component can be used individually by 1 type, and can also be used in combination of 2 or more types at any ratio.

Relative to the total mass of chemical mechanical polishing aqueous dispersion, component (B) The lower limit of the content is preferably 0.001 mass%, more preferably 0.01 mass%, and particularly preferably 0.03 mass%. On the other hand, the upper limit of the content of component (B) is preferably 1% by mass, more preferably 0.5% by mass, and particularly preferably 0.15% by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion. If the content of component (B) is within the above range, the effect of passivating the surface of the wiring metal material or the barrier metal material and forming an oxide layer can be sufficiently obtained, so that the polishing speed can be increased. In addition, since excessive etching is suppressed, corrosion of wiring metal materials may be reduced.

1.3.(C) Compounds with hydroxyl and carboxyl groups

The chemical mechanical polishing aqueous dispersion of this embodiment contains (C) at least one selected from the group consisting of compounds having a hydroxyl group and a carboxyl group and salts thereof. Generally, when (B) iron salt is used at a pH in an alkaline range, a precipitate of iron hydroxide is generated, and the function of (B) iron salt as an oxidizing agent is impaired. However, since the chemical mechanical polishing aqueous dispersion of this embodiment contains the component (C), it is possible to suppress the occurrence of precipitation of iron hydroxide derived from the iron salt (B) even at a pH in an alkaline range. As a result, the stability of the chemical mechanical polishing aqueous dispersion of this embodiment becomes good, and the (B) iron salt functions as an oxidizing agent, so that the wiring metal material and the barrier metal material can be polished at high speed.

Hereinafter, the mechanism by which component (C) suppresses the generation of precipitates derived from iron salt (B) will be described in detail. Generally, as a chelating agent that improves the stability of metals in a solution, a chelating agent having only a plurality of carboxyl groups as an acid group, such as ethylenediaminetetraacetic acid or diethylenetriaminepentacetic acid, is used. However, since these chelating agents only have carboxyl groups, they cannot fully form a chelate complex with iron ions at a pH in the alkaline range. As a result, Precipitates such as iron hydroxide are produced. On the other hand, component (C) also has sufficient ability to form a chelate complex with iron ions at a pH in the alkaline range. The reason for this is presumably because (C) component has a hydroxyl group and therefore has high water solubility, so that the chelate complex is formed preferentially compared to the chelating agent.

Component (C) is preferably at least one selected from the group consisting of compounds having a hydroxyl group, a carboxyl group, and an amine structure, and salts thereof. Furthermore, component (C) is more preferably at least one selected from the group consisting of polycarboxylic acids having a hydroxyl group and two or more amine structures and salts thereof. That is, a compound having one or more hydroxyl groups, two or more carboxyl groups, and two or more amine structures is more preferred.

The molecular weight of component (C) is preferably from 80 to 1,000, more preferably from 100 to 700. When the molecular weight of component (C) is within the above range, it is easily dissolved in an aqueous dispersion, and therefore the occurrence of precipitates derived from component (B) may be easily suppressed.

Specific examples of component (C) include: N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, N,N-bis(2-hydroxyethyl)glyamine acid, N-(2-hydroxyethyl)iminodiacetic acid, and N,N'-ethylidenebis[N-(2-hydroxybenzyl)glycine], etc. Among these, in order to increase the polishing speed of wiring metal materials and the like while suppressing excessive etching, and to improve the dispersion stability of the chemical mechanical polishing aqueous dispersion, N-(2-hydroxyethyl)ethylenediamine is preferred. -N,N',N'-triacetic acid, N,N-bis(2-hydroxyethyl)glycine, N,N'-ethylidenebis[N-(2-hydroxybenzyl)glycine ]. One type of component (C) may be used alone, or two or more types may be used in combination at any ratio.

Relative to the total mass of chemical mechanical polishing aqueous dispersion, component (C) The lower limit of the content is preferably 0.005 mass%, more preferably 0.01 mass%, and particularly preferably 0.03 mass%. If the content of component (C) is more than the lower limit, interaction with component (B) is likely to occur, and the polishing speed of the surface to be polished may be further increased. On the other hand, the upper limit of the content of component (C) is preferably 1% by mass, more preferably 0.5% by mass, and particularly preferably 0.1% by mass relative to the total mass of the chemical mechanical polishing aqueous dispersion. If the content of component (C) is less than the upper limit, excessive etching may be suppressed.

In addition, in the chemical mechanical polishing aqueous dispersion of this embodiment, when the content of the component (C) relative to the total mass of the chemical mechanical polishing aqueous dispersion is M _C (mol), (B ) component is expressed as M _B (mol), the molar ratio M _C / _MB of these components is preferably 0.3 or more and 3.0 or less, more preferably 0.4 or more and 2.5 or less, particularly preferably 0.5 or more and 2.0 the following. If the molar ratio _MC / _MB is within the above range, almost all the iron ions generated by the dissociation of the component (B) can be chelated by the component (C) at a pH in the alkaline range, Therefore, the generation of precipitates such as iron hydroxide can be effectively suppressed. As a result, the stability of the chemical mechanical polishing aqueous dispersion of this embodiment becomes good, and the (B) iron salt can function as an oxidizing agent, so that the wiring metal material and the barrier metal material can be polished at high speed.

1.4.(D) Organic acids and their salts

The chemical mechanical polishing aqueous dispersion of this embodiment may also contain (D) different from the (C) component (D) at least one selected from the group consisting of organic acids and their salts (hereinafter also referred to as "( D) ingredient"). Since the chemical mechanical polishing aqueous dispersion of this embodiment contains the component (D), the following may occur: (D) The ingredients are distributed on the surface to be ground to increase the grinding speed and inhibit the precipitation of metal salts during the grinding process. In addition, by distributing component (D) on the surface to be polished, damage caused by etching and corrosion of the surface to be polished may be reduced.

As the component (D), an organic acid and a salt thereof having the ability to coordinate ions or atoms of elements including the wiring metal material are preferred. As such component (D), an organic acid having 0 to 1 hydroxyl group and 1 to 2 carboxyl groups in one molecule is more preferred, and an organic acid having 0 to 1 hydroxyl group and 1 carboxyl group in one molecule is particularly preferred. An organic acid with ~2 carboxyl groups and a first acid dissociation constant pKa of 1.5~4.5. If it is such a component (D), it has a high ability to coordinate on the surface of wiring metal materials and the like, and therefore the polishing speed of wiring metal materials and the like can be increased. In addition, such component (D) can stabilize metal ions generated by polishing of wiring metal materials and the like and suppress precipitation of metal salts. Therefore, it is possible to obtain a high degree of flatness while suppressing surface roughness of the surface to be polished, and to reduce the occurrence of polishing damage to wiring metal materials and the like.

Among the components (D), specific examples of organic acids include lactic acid, tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, malic acid, and propylene acid. Diacid, glutaric acid, succinic acid, benzoic acid, p-hydroxybenzoic acid, quinolinic acid, quinaldic acid, amide sulfate; glycine, alanine, aspartic acid, glutamic acid , lysine, arginine, tryptophan, aromatic amino acids and heterocyclic amino acids and other amino acids. Among these, maleic acid, succinic acid, lactic acid, malonic acid, p-hydroxybenzoic acid and glycolic acid are preferred, and malonic acid is more preferred. (D) Component can be used individually by 1 type, and can also be used in combination of 2 or more types at any ratio.

Among the components (D), specific examples of organic acid salts may be salts of the above-described illustrated organic acids, or may be reacted with a base separately added to the chemical mechanical polishing aqueous dispersion to form salts of the above-mentioned organic acids. . Examples of such bases include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, organic bases such as tetramethyl ammonium hydroxide (TMAH), and choline. compounds, and ammonia, etc.

The lower limit of the content of component (D) is preferably 0.001 mass%, more preferably 0.01 mass%, and particularly preferably 0.1 mass% relative to the total mass of the chemical mechanical polishing aqueous dispersion. On the other hand, the upper limit of the content of component (D) is preferably 2 mass %, more preferably 1 mass %, and particularly preferably 0.5 mass %, relative to the total mass of the chemical mechanical polishing aqueous dispersion. If the content of component (D) is within the above range, a sufficient polishing speed for polishing the wiring metal material and the barrier metal material can be obtained, and the precipitation of the metal salt is suppressed, thereby reducing the number of polished materials. The generation of surface grinding damage.

1.5.(E)Sodium hydroxide, potassium hydroxide, ammonium hydroxide

In order to adjust the pH, the chemical mechanical polishing aqueous dispersion of this embodiment may also contain (E) at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide (hereinafter also referred to as "(E)Component"). By adding component (E) to the chemical mechanical polishing aqueous dispersion of this embodiment, the pH of the chemical mechanical polishing aqueous dispersion can be easily adjusted to 7 or more and 14 or less.

As component (E), at least one selected from the group consisting of sodium hydroxide and potassium hydroxide is preferred, and potassium hydroxide is more preferred. (E) Ingredient can be used alone Use one kind or combine two or more kinds in any proportion.

1.6. Other ingredients

In addition to water as the main liquid medium, the chemical mechanical polishing aqueous dispersion of this embodiment may also contain surfactants, nitrogen-containing heterocyclic compounds, oxidizing agents, water-soluble polymers, etc., if necessary.

<Water>

The chemical mechanical polishing aqueous dispersion of this embodiment contains water as the main liquid medium. Water is not particularly limited, but pure water is preferred. Water only needs to be prepared as the remainder of the constituent materials of the chemical mechanical polishing aqueous dispersion, and the content of water is not particularly limited.

<Surfactant>

The chemical mechanical polishing aqueous dispersion of this embodiment may also contain a surfactant. By containing a surfactant, it may be possible to impart appropriate viscosity to the chemical mechanical polishing aqueous dispersion.

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 alkyl benzene sulfonates, alkyl naphthalene sulfonates, and α-olefin sulfonates; Sulfates such as higher alcohol sulfate ester salts, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, etc.; fluorine-containing surfactants such as perfluoroalkyl compounds, etc. Examples of the cationic surfactant include aliphatic amine salts, aliphatic ammonium salts, and the like. Examples of nonionic surfactants include: acetylene glycol, acetylene glycol ethylene oxide Nonionic surfactants with triple bonds such as 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 aqueous dispersion of this embodiment contains a surfactant, the content of the surfactant is preferably 0.001 mass% to 5 mass% relative to the total mass of the chemical mechanical polishing aqueous dispersion, and more preferably The optimal range is 0.001 mass% to 3 mass%, and the particularly optimal range is 0.01 mass% to 1 mass%.

<Nitrogen-containing heterocyclic compounds>

The chemical mechanical polishing aqueous dispersion of this embodiment may contain a nitrogen-containing heterocyclic compound. By containing the nitrogen-containing heterocyclic compound, excessive etching of the wiring metal material can be suppressed and surface roughness after polishing can be prevented.

In this specification, the term "nitrogen-containing heterocyclic compound" refers to an organic compound containing at least one heterocyclic ring selected from a heterocyclic five-membered ring and a heterocyclic six-membered ring having at least one nitrogen atom. Examples of the heterocyclic ring include heterocyclic five-membered rings such as pyrrole structure, imidazole structure, and triazole structure; heterocyclic six-membered rings such as pyridine structure, pyrimidine structure, pyridazine structure, and pyrazine structure. These heterocyclic rings may also form condensed rings. Specific examples include: indole structure, isoindole structure, benzimidazole structure, benzotriazole structure, quinoline structure, isoquinoline structure, quinazoline structure, cinnoline structure, and phthalazine (phthalazine) structure, quinoxaline structure, acridine structure, etc. Among the heterocyclic compounds having such a structure, those having a pyridine structure, a quinoline structure, a benzimidazole structure or a benzotriazole structure are preferred.

Specific examples of nitrogen-containing heterocyclic compounds include: aziridine, pyridine, Pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzisoquinoline, purine, pteridine, triazole, triazolidine (triazolidine), benzene Benzotriazole, carboxybenzotriazole, etc., and further examples include derivatives having these skeletons. Among these, benzotriazole, triazole, imidazole and carboxybenzotriazole are preferred. These nitrogen-containing heterocyclic compounds may be used singly or in combination of two or more.

When the chemical mechanical polishing aqueous dispersion of this embodiment contains a nitrogen-containing heterocyclic compound, the content of the nitrogen-containing heterocyclic compound is preferably 0.05 mass % to 2 based on the total mass of the chemical mechanical polishing aqueous dispersion. Mass%, more preferably 0.1 mass% to 1 mass%, particularly preferably 0.2 mass% to 0.6 mass%.

<Water-soluble polymer>

The chemical mechanical polishing aqueous dispersion of this embodiment may contain a water-soluble polymer. By containing a water-soluble polymer, it may be adsorbed to the surface to be polished such as a wiring metal material, thereby reducing polishing friction. As the water-soluble polymer, polycarboxylic acid is preferred, and polyacrylic acid, polymaleic acid, and copolymers of these acids are more preferred. These water-soluble polymers may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the water-soluble polymer is preferably from 1,000 to 1,000,000, more preferably from 3,000 to 800,000. If the weight average molecular weight of the water-soluble polymer is within the above range, the water-soluble polymer may be easily adsorbed to the surface to be polished such as a wiring metal material, and polishing friction may be further reduced. As a result, the occurrence of polishing damage in the surface to be polished may be more effectively reduced. In addition, the so-called "weight average molecular weight (Mw)" in this specification refers to the value measured by gel permeation chromatography (Gel Permeation Chromatography, GPC). Weight average molecular weight converted to polyethylene glycol.

When the chemical mechanical polishing aqueous dispersion of this embodiment contains a water-soluble polymer, the content of the water-soluble polymer is preferably 0.01 mass% to 1 mass% relative to the total mass of the chemical mechanical polishing aqueous dispersion. , more preferably 0.03 mass% to 0.5 mass%.

Furthermore, although the content of the water-soluble polymer also depends on the weight average molecular weight (Mw) of the water-soluble polymer, it is preferable that the viscosity of the chemical mechanical polishing aqueous dispersion is less than 10 mPa. s method to adjust. If the viscosity of the chemical mechanical polishing aqueous dispersion is less than 10 mPa. s, it is easy to polish wiring metal materials and the like at high speed. Since the viscosity is appropriate, the chemical mechanical polishing aqueous dispersion can be stably supplied on the polishing cloth.

<Oxidant>

The chemical mechanical polishing aqueous dispersion of this embodiment may contain an oxidizing agent different from the component (B). By containing such an oxidizing agent, the surface to be polished can be oxidized and the complex reaction with the components of the polishing fluid can be promoted, thereby forming a fragile modified layer on the surface to be polished. Therefore, the polishing speed may be further increased.

Examples of such an oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, potassium hypochlorite, ozone, potassium periodate, peracetic acid, and the like. Among these oxidants, potassium periodate, potassium hypochlorite and hydrogen peroxide are preferred, and hydrogen peroxide is more preferred. The chemical mechanical polishing aqueous dispersion of this embodiment causes a strong oxidation reaction (Fenton reaction) by using (B) iron salt and hydrogen peroxide in combination, and may therefore be able to polish tungsten as a wiring metal material at high speed. These oxidants can be used individually, or Two or more types can be used in combination.

When the chemical mechanical polishing aqueous dispersion of the present embodiment contains an oxidizing agent different from the component (B), the lower limit of the content of the oxidizing agent is preferably 0.001 relative to the total mass of the chemical mechanical polishing aqueous dispersion. Mass%, more preferably 0.005 mass%, particularly preferably 0.01 mass%. On the other hand, the upper limit of the content of the oxidizing agent is preferably 5% by mass, more preferably 3% by mass, and particularly preferably 1.5% by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion. Furthermore, when an oxidizing agent different from the component (B) is contained within the above range, an oxide film may be formed on the surface of the polished surface containing metal such as wiring metal materials, so it is preferable to polish immediately before CMP. Add oxidizing agent before step.

1.7.pH

The pH value of the chemical mechanical polishing aqueous dispersion of this embodiment is 7 or more and 14 or less, preferably 8 or more and 12 or less, more preferably 8.5 or more and 11.5 or less. If the pH value is in the above range, the dispersion stability of (A) the abrasive particles is improved, and therefore the polishing speed of the wiring metal material and the barrier metal material can be increased. In particular, silica is negatively charged in the alkaline region with a pH value of 7 to 14, so the dispersion stability is improved.

Furthermore, by containing the component (C), the chemical mechanical polishing aqueous dispersion of this embodiment can suppress the generation of iron hydroxide precipitates derived from the iron salt (B) at a pH in the alkaline range. As a result, (B) the iron salt functions as an oxidizing agent at a pH in an alkaline region, thereby passivating the surface of the wiring metal material or the barrier metal material to form an oxide layer. Furthermore, the oxide layer can be removed at high speed by mechanical polishing action using the abrasive grains (A) which are excellent in dispersion stability.

The pH of the chemical mechanical polishing aqueous dispersion of this embodiment can be adjusted by appropriately increasing or decreasing the (B) component, the (C) component, the (D) component, the (E) component, etc. Adjust the amount added.

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

1.8. Purpose

One of the characteristics of the chemical mechanical polishing aqueous dispersion of this embodiment is that by setting the pH to 7 or more and 14 or less, the dispersion stability of (A) the abrasive grains is improved, and (B) the iron salt is It functions as an oxidizing agent and passivates the surface of the wiring metal material or the barrier metal material to form an oxide layer. The oxide layer can be removed at high speed by the mechanical polishing action of (A) abrasive grains. Therefore, the chemical mechanical polishing aqueous dispersion of this embodiment is suitable as a polishing material for chemical mechanical polishing of a polished surface containing tungsten, copper, cobalt, or titanium among semiconductor manufacturing materials. , ruthenium and other wiring metal materials; any one or more of barrier metal materials such as titanium nitride and tantalum nitride.

In the chemical mechanical polishing, for example, the polishing device 100 shown in FIG. 1 can be used. FIG. 1 is a perspective view schematically showing the polishing device 100 . The chemical mechanical polishing is performed by supplying slurry (chemical mechanical polishing aqueous dispersion) 44 from the slurry supply nozzle 42 and rotating a turntable 48 to which the polishing cloth 46 is attached. A carrier head 52 holding the substrate 50 is in contact. In addition, the water supply nozzle 54 and the dresser are also shown in FIG. 1 56.

The grinding load of the carrying head 52 can be selected in the range of 0.7psi~70psi, preferably 1.5psi~35psi. In addition, the rotation speed of the turntable 48 and the carrying head 52 can be appropriately selected in the range of 10rpm~400rpm, preferably 30rpm~150rpm. The flow rate of the slurry (water-based chemical mechanical polishing dispersion) 44 supplied from the slurry supply nozzle 42 can be selected in the range of 10 mL/min to 1,000 mL/min, and is preferably 50 mL/min to 400 mL/min.

Examples of commercially available polishing devices include models "EPO-112" and "EPO-222" manufactured by Ebara Manufacturing Co., Ltd.; models "LGP-510" and "LGP" manufactured by Lapmaster SFT Co., Ltd. -552"; models "Mirra" and "Reflexion" manufactured by Applied Materials; model "POLI" manufactured by G&P TECHNOLOGY - 400L"; model "Reflexion LK" manufactured by AMAT; model "FLTec-15" manufactured by FILTEC, etc.

2. Method for producing chemical mechanical polishing aqueous dispersion

The method for producing a chemical mechanical polishing aqueous dispersion according to this embodiment includes: a first step of dispersing or dissolving (A) abrasive grains, (B) iron salts, and (C) compounds having hydroxyl groups and carboxyl groups in an aqueous medium; Obtain an aqueous dispersion; in the second step, use (E) at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and ammonium hydroxide to adjust the pH of the aqueous dispersion to 7 or more and 14 or less .

In the first step, it is preferable to make the (A) component, (B) component, (C) An aqueous dispersion is prepared by dissolving or dispersing the components in a liquid medium such as water in the order of component (B)→component (C)→component (A) or component (C)→component (B)→component (A). . The method of dissolving or dispersing is not particularly limited, and any method can be applied as long as it can be uniformly dissolved or dispersed.

In the second step, component (E) is added to the obtained aqueous dispersion to adjust the pH of the aqueous dispersion to a predetermined value in the range of 7 or more and 14 or less. The second step may be performed after the first step, or may be performed simultaneously with the first step, or may be performed simultaneously with the first step, and then the second step may be performed.

In addition, in the method for producing a chemical mechanical polishing aqueous dispersion according to this embodiment, as the third step, hydrogen peroxide or the like may be further added to the aqueous dispersion after the first step and the second step, in addition to (B) An oxidant other than the component is used to prepare a chemical mechanical polishing aqueous dispersion. In the case where the oxidizing agent is hydrogen peroxide, hydrogen peroxide is unstable, easily releases oxygen, and easily generates hydroxyl radicals with strong oxidizing power. Therefore, it is better to perform the third step immediately before chemical mechanical polishing. .

In addition, the chemical mechanical polishing aqueous dispersion obtained in this way can also be prepared as a concentrated type stock solution, and diluted with a liquid medium such as water before use.

3.Examples

The present invention will be described below through examples, but the present invention is not limited to these examples at all. In addition, "parts" and "%" in this example are based on mass unless otherwise specified.

3.1.Example 1

3.1.1. Preparation of aqueous dispersion for chemical mechanical grinding

0.2% by mass of malonic acid, 0.05% by mass of iron nitrate, 0.057% by mass of hydroxyethylethylenediaminetriacetic acid, a prescribed amount of potassium hydroxide having the following pH, and 0.5% by mass of silica abrasive grains were added to pure water in a polyethylene bottle with a capacity of 1 liter, and then thoroughly stirred to obtain the chemical mechanical polishing aqueous dispersion of Example 1 with pH 9.2.

3.1.2. Evaluation method

(1) Evaluation of grinding speed

Using the chemical mechanical polishing aqueous dispersion prepared as described above, test pieces obtained by cutting a tungsten substrate and a titanium nitride substrate without a wiring pattern on a resin substrate into 3 cm × 3 cm were used as the objects to be polished, as follows: A chemical mechanical polishing test was performed for 1 minute under grinding conditions. The evaluation criteria are as follows. The results are shown together in Table 1.

<Grinding conditions>

． Grinding device: Model "FLTec-15" manufactured by FILTEC

． Polishing pad: "H600" manufactured by Fujibo

． Chemical mechanical polishing aqueous dispersion supply rate: 100mL/min

． Pressure plate speed: 100rpm

． Head speed: 90rpm

． Head pressing pressure: 3.8psi

． Resistivity evaluation device for tungsten and titanium nitride: Model manufactured by NPS Corporation (MODEL)Σ-5

． Polishing rate of tungsten and titanium nitride (Å/min) = (((volume resistivity unique to each substrate/resistance value of each substrate before polishing)-(volume resistivity unique to each substrate/resistance value of each substrate after polishing) ))/grinding time (seconds))×60

(Grinding speed evaluation criteria)

． If at least one of the conditions of tungsten polishing rate of 40Å/min or more and titanium nitride polishing rate of 25Å/min or more is not met, it is "×"

． "△" is met when all conditions are met: tungsten polishing rate is 40Å/min or more and titanium nitride polishing rate is 25Å/min or more

． "○" is obtained when all the conditions for a tungsten polishing rate of 50Å/min or more and a titanium nitride polishing rate of 30Å/min or more are met.

In addition, when the evaluation result is "○", the condition of "△" is also satisfied, but "○" takes priority.

(2) Evaluation of etching rate

The tungsten substrate and the cobalt substrate without wiring patterns on the resin substrate were respectively cut into 1 cm × 3 cm to obtain test pieces. The test pieces were heated to 60°C in the chemical mechanical polishing aqueous dispersion prepared and then immersed for 5 minute. The etching rates of tungsten and cobalt are determined by the following equations.

． Tungsten and cobalt resistivity evaluation device: Model (MODEL) Σ-5 manufactured by NPS Corporation

． Etching rate of tungsten and cobalt (Å/min) = (((volume resistivity unique to each substrate/resistance value of each substrate before immersion)-(volume resistivity unique to each substrate/resistance value of each substrate after immersion))) ×10 ¹⁰ )/immersion time (seconds) ×60

(Etching rate evaluation standard)

． If at least one of the conditions of tungsten etching rate less than 80Å/min and cobalt etching rate less than 60Å/min is not met, it is "×"

． "△" is met when all conditions are met: the tungsten etching rate is less than 80Å/min and the cobalt etching rate is less than 60Å/min.

． "○" is met when all conditions are met: the tungsten etching rate is less than 30Å/min and the cobalt etching rate is less than 50Å/min.

In addition, when the evaluation result is "○", the condition of "△" is also satisfied, but "○" takes priority.

(3) Evaluation of stability

The prepared chemical mechanical polishing aqueous dispersion was allowed to stand at room temperature to visually confirm whether there was sediment at the bottom of the polyethylene bottle.

(Evaluation criteria for stability)

． If no sedimentation occurs even after being left for more than 2 weeks, it is classified as "○"

． The case where sedimentation occurs during less than 2 weeks of standing is "△"

． The case where sedimentation occurs immediately after preparation is "×"

3.2. Example 2 to Example 11 and Comparative Example 1 to Comparative Example 2

Except for changing the type and content of each component as described in Table 1 below, a chemical mechanical polishing aqueous dispersion was prepared in the same manner as in Example 1, and each evaluation test was conducted in the same manner as in Example 1.

3.3.Example 12

0.2% by mass of malonic acid, 0.05% by mass of iron nitrate, 0.057% by mass of hydroxyethylethylenediaminetriacetic acid, a prescribed amount of potassium hydroxide having the following pH, and 0.5% by mass of silica abrasive grains were added to pure water in a polyethylene bottle with a capacity of 1 liter, and then thoroughly stirred to obtain an aqueous dispersion with a pH of 9.2. Thereafter, hydrogen peroxide water was added as an oxidant so as to obtain 1 mass % of hydrogen peroxide, and the chemical mechanical polishing aqueous dispersion of Example 12 was obtained. The polishing speed of the tungsten substrate and the stability of the chemical mechanical polishing aqueous dispersion were evaluated in the same manner as in Example 1, except that the chemical mechanical polishing aqueous dispersion obtained in this way was used.

3.4. Reference example 1

0.2% by mass of malonic acid, a predetermined amount of potassium hydroxide having a pH as described below, and 0.5% by mass of silica abrasive grains were respectively added to pure water in a polyethylene bottle with a capacity of 1 liter, and then thoroughly stirred. , an aqueous dispersion with pH 9.2 was obtained. Thereafter, hydrogen peroxide water was added as an oxidizing agent so as to obtain 1% by mass of hydrogen peroxide, and the chemical mechanical polishing aqueous dispersion of Reference Example 1 was obtained. The polishing speed of the tungsten substrate and the stability of the chemical mechanical polishing aqueous dispersion were evaluated in the same manner as in Example 1, except that the chemical mechanical polishing aqueous dispersion obtained in this way was used.

3.5. Evaluation results

The compositions of the chemical mechanical polishing aqueous dispersions of each Example and each Comparative Example and each evaluation result are shown in Table 1 and Table 2 below.

For each component in Table 1 and Table 2, the following products or reagents were used.

<Abrasive grain>

． Silica: manufactured by Fuso Chemical Industry Co., Ltd., colloidal silica, average particle size 75nm

<Iron salt>

． Ferric nitrate: Trade name "FN-376" manufactured by Tama Chemical Industry Co., Ltd.

． Iron sulfate: Trade name "Iron(II) sulfate heptahydrate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

<Compounds having hydroxyl and carboxyl groups>

． Hydroxyethylethylenediaminetriacetic acid: Product manufactured by Chelest Company Name "Chelest HA"

． N,N-bis(2-hydroxyethyl)glycine: Trade name "Chelest GA" manufactured by Chelest Company

<Organic acid>

． Malonic acid: Trade name "malonic acid" manufactured by Fuso Chemical Industry Co., Ltd.

<Oxidant>

． Hydrogen peroxide: Trade name "Hydrogen peroxide water (30%)" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

According to the chemical mechanical polishing aqueous dispersions of Examples 1 to 11, it is known that both the tungsten substrate and the titanium nitride substrate can be polished at high speed, and both the tungsten substrate and the cobalt substrate can reduce the etching rate. In addition, it is known that the chemical mechanical polishing aqueous dispersions of Examples 1 to 11 contain the component (C), thereby suppressing the generation of precipitates derived from the component (B) at a pH in the alkaline region and being stable. sexual enhancement.

The chemical mechanical polishing aqueous dispersion of Comparative Example 1 did not contain the component (B) and the component (C), so neither the tungsten substrate nor the titanium nitride substrate could be polished at high speed.

Since the chemical mechanical polishing aqueous dispersion of Comparative Example 2 did not contain component (C), precipitates derived from component (B) were generated and the stability was impaired. Therefore, polishing speed evaluation and etching rate evaluation could not be performed.

In addition, it is known that the chemical mechanical polishing aqueous dispersion of Example 12 causes a strong oxidation reaction (Fenton reaction) by combining ferric nitrate and hydrogen peroxide as an oxidizing agent. Compared with the chemical mechanical polishing aqueous dispersion of component (C), the tungsten substrate can be polished at a higher speed.

From the above results, it can be seen that according to the chemical mechanical polishing aqueous dispersion of the present invention, excessive etching of the polished surface containing the wiring metal material and the barrier metal material can be suppressed, and the polished surface can be polished at high speed. In addition, it was found that according to the chemical mechanical polishing aqueous dispersion of the present invention, the generation of precipitates derived from component (B) can be suppressed and the stability is also improved.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes structures that are substantially the same as those described in the embodiments (for example, structures with the same functions, methods, and results, or structures with the same objects and effects). In addition, the present invention includes structures in which non-essential parts of the structures described in the embodiments are replaced. In addition, the present invention includes a configuration that exhibits the same operation and effect as the configuration described in the embodiment or a configuration that can achieve the same purpose. In addition, the present invention includes a configuration obtained by adding publicly known techniques to the configuration described in the embodiments.

42‧‧‧Slurry supply nozzle

44‧‧‧Slurry (water-based dispersion for chemical mechanical polishing)

46‧‧‧Abrasive cloth

48‧‧‧Turntable

50‧‧‧Substrate

52‧‧‧Carrying head

54‧‧‧Water supply nozzle

56‧‧‧Finisher

100‧‧‧Grinding device

Claims (9)

A chemical mechanical polishing aqueous dispersion, including: (A) abrasive particles; (B) iron salt; and (C) component, at least one selected from the group consisting of compounds with hydroxyl and carboxyl groups and their salts, The pH is 7 or more and 14 or less, and the iron salt (B) contains at least one selected from the group consisting of iron nitrate and iron sulfate. The chemical mechanical polishing aqueous dispersion described in claim 1, wherein the component (C) contains at least one selected from the group consisting of compounds having a hydroxyl group, a carboxyl group, and an amine structure, and their salts. The chemical mechanical polishing aqueous dispersion described in the first or second patent scope, wherein the component (C) contains polycarboxylic acids and their salts selected from the group consisting of polycarboxylic acids having hydroxyl groups and two or more amine structures. at least one of the groups. The chemical mechanical polishing aqueous dispersion described in item 1 or 2 of the patent application, wherein the component (C) contains a component selected from the group consisting of N-(2-hydroxyethyl)ethylenediamine-N,N', A group consisting of N'-triacetic acid, N,N-bis(2-hydroxyethyl)glycine and N,N'-ethylidenebis[N-(2-hydroxybenzyl)glycine] at least one of them. The chemical mechanical polishing aqueous dispersion described in the first or second patent scope, wherein the content of the component (C) is set to M _C (mol), and the content of the iron salt (B) is When the content is _MB (mol), the molar ratio M _C / _MB is 0.3 or more and 3.0 or less. The chemical mechanical grinding aqueous dispersion described in the first or second item of the patent application further contains (D) at least one selected from the group consisting of organic acids and their salts (the (C) ) except ingredients). The chemical mechanical grinding aqueous dispersion described in item 1 or 2 of the patent application further contains (E) at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and ammonium hydroxide. . The chemical mechanical polishing aqueous dispersion as described in item 1 or 2 of the patent application is used to contain a group selected from the group consisting of tungsten, copper, cobalt, titanium, ruthenium, titanium nitride and tantalum nitride. Polishing of at least one of the above substrates. A method for manufacturing a chemical mechanical grinding aqueous dispersion, including: a first step of dispersing or dissolving (A) abrasive grains, (B) iron salts, and (C) compounds with hydroxyl and carboxyl groups in an aqueous medium to obtain an aqueous dispersion. dispersion; and a second step of adjusting the pH of the aqueous dispersion to 7 or more and 14 or less using (E) at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide.