TW202007757A - Chemical mechanical polishing aqueous dispersion capable of polishing a substrate including tungsten and an insulating film at high speed and reducing generation of polishing scratches on a surface to be polished - Google Patents

Abstract

This invention provides a chemical mechanical polishing aqueous dispersion capable of polishing a substrate including tungsten and an insulating film at high speed and reducing generation of polishing scratches on a surface to be polished. An embodiment of the chemical mechanical polishing aqueous dispersion according to the present invention comprises: (A) silica abrasive grains having a group capable of forming a sulfonate on the surface thereof, (B) at least one selected from the group consisting of metal nitrate and metal sulfate, and (C) at least one selected from the group consisting of organic acids and salts thereof which has a pH value of 1 or more and 6 or less.

Description

Water-based dispersion for chemical mechanical grinding

The invention relates to a water-based dispersion for chemical mechanical polishing.

It has been found that chemical mechanical polishing (CMP) is rapidly gaining popularity in flattening techniques and the like in the manufacture of semiconductor devices. The CMP is a technique in which the body to be polished is pressed against the polishing pad, and the water-based dispersion for chemical mechanical polishing is supplied to the polishing pad while sliding the body to be polished against the polishing pad to chemically and mechanically polish the body to be polished Grind.

In recent years, with the increase in the fineness of semiconductor devices, the miniaturization of wiring layers including wirings, plugs, and the like formed in semiconductor devices has progressed. 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 material, a barrier metal material for preventing the wiring material from diffusing to an inorganic material film, and the like. Here, as the insulating film material, for example, silicon dioxide is mainly used, as the wiring material, for example, copper or tungsten is mainly used, and as the barrier metal material, for example, tantalum nitride or titanium nitride is mainly used.

Moreover, in tungsten plug and interconnection processes, there is a need for chemical mechanical polishing compositions that etch (etch) tungsten at a slower rate. For example, it is proposed to include colloidal silica with a permanent positive charge of 6 mV or more ( chemical mechanical polishing composition such as colloidal silica), amine compound, ferric nitrate, etc. (for example, refer to Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Special Publication No. 2017-514295

[Problems to be solved by the invention]

The chemical mechanical polishing composition described in Patent Document 1 improves the dispersibility of the abrasive particles and increases the polishing speed of the tungsten film by setting the surface of the abrasive particles to a stable positive charge. It is presumed that the reason is that by using abrasive grains having a high value of zeta potential, the electrostatic repulsive force is used to suppress the aggregation of the abrasive grains, and the adhesion effect with the tungsten film is remarkably exhibited.

However, with the recent multi-layer wiring, in the actual tungsten plug and interconnection process, there is a need for a technology that uses CMP to remove tungsten other than wiring, and can simultaneously make the interlayer insulating film surrounding tungsten as wiring flattened. Although the chemical mechanical polishing composition described in Patent Document 1 can increase the polishing speed of the tungsten film, it is difficult to polish the insulating film at high speed.

Therefore, some aspects of the present invention provide a water-based dispersion for chemical mechanical polishing, which can polish a substrate including tungsten and an insulating film at high speed, and can reduce the occurrence of polishing damage in the polished surface. [Technical means to solve the problem]

The present invention is made to solve at least a part of the problems described above, and can be implemented in any of the following forms.

One form of the chemical mechanical polishing aqueous dispersion of the present invention contains: (A) Silica abrasive grains having a group capable of forming a sulfonate on the surface, (B) at least one selected from the group consisting of metal nitrate and metal sulfate, and (C) At least one selected from the group consisting of organic acids and their salts, and having a pH value of 1 or more and 6 or less.

According to one aspect of the chemical mechanical polishing aqueous dispersion, it may further contain (D) a water-soluble polymer.

According to any aspect of the chemical mechanical polishing aqueous dispersion, the (A) silicon dioxide abrasive particles may have a permanent negative charge of -20 mV or less.

According to any form of the chemical mechanical polishing water-based dispersion, the electrostatic interaction coefficient with the polishing object may be negative.

According to any form of the chemical mechanical polishing aqueous dispersion, it may be used for polishing silicon-containing substrates.

According to any aspect of the chemical mechanical polishing aqueous dispersion, the silicon-containing substrate may have tungsten. [Effect of invention]

According to the water-based dispersion for chemical mechanical polishing of the present invention, a substrate including tungsten and an insulating film can be polished at a high speed, and the occurrence of polishing damage in the polished surface can be reduced. Furthermore, according to the aqueous dispersion of chemical mechanical polishing of the present invention, the dispersion stability of the abrasive particles contained in the dispersion can be improved.

Hereinafter, suitable embodiments of the present invention will be described in detail. In addition, the present invention is not limited to the following embodiments, and includes various modifications implemented within the scope of not changing the gist of the present invention.

In this specification, the numerical range described using "-" is meant to include the numerical values described before and after "-" as the lower limit and upper limit.

The "wiring material" refers 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 “barrier metal material” refers to a material such as tantalum nitride, titanium nitride, etc., which is laminated with the wiring material in order to improve the reliability of the wiring.

1. Aqueous dispersion for chemical mechanical grinding The aqueous dispersion for chemical mechanical polishing of this embodiment contains: (A) silica abrasive grains having a group capable of forming a sulfonate on the surface (hereinafter, also referred to as "(A) component"), and (B) At least one of the group consisting of free metal nitrate and metal sulfate (hereinafter, also referred to as "(B) component"), and (C) at least one selected from the group consisting of organic acids and their salts One (hereinafter, also referred to as "(C) component"), and the pH value is 1 or more and 6 or less. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion of the present embodiment will be described in detail.

1.1 (A) Silicon dioxide abrasive grains The aqueous dispersion for chemical mechanical polishing of the present embodiment contains (A) silica abrasive particles having a group capable of forming a sulfonate on the surface. The component (A) has a function of mechanically polishing wiring materials, insulating film materials, and barrier metal film materials, and increasing the polishing rate of these materials. (A) Since the component has a group capable of forming a sulfonate on the surface, among these materials, the polishing rate of a material containing tungsten and silicon can be particularly improved. In addition, since the component (A) has a group capable of forming a sulfonate on the surface, the electrostatic repulsive force improves the dispersibility or dispersion stability. As a result, the occurrence of polishing damage in the polished surface can be reduced.

（式（1）中，R表示亞烷基、亞芳基、或這些的組合、或單鍵）The "group capable of forming a sulfonate" specifically refers to a group represented by the following general formula (1). [Chemical 1]

(In formula (1), R represents an alkylene group, an arylene group, or a combination of these, or a single bond)

Examples of the component (A) include fumed silica and colloidal silica. Colloidal silica is preferred. As the colloidal silica, for example, colloidal silica produced by the method described in Japanese Patent Laid-Open No. 2003-109921 can be used.

The method for introducing a group capable of forming a sulfonate on the surface of silica abrasive grains is not particularly limited, and examples thereof include International Publication No. 2011/093153, Journal of Industrial and Engineering Chemistry, J. Ind. Eng. Chem.) (Vol. 12, No. 6, (2006) 911-917) and other methods for modifying the surface of silica abrasive grains.

As an example of a method for introducing a group capable of forming a sulfonate on the surface of silica abrasive grains, a method of fixing a group capable of forming a sulfonate to the surface of silica abrasive grains via a covalent bond can be cited. Specifically, it can be achieved by sufficiently stirring the silica dioxide abrasive particles and the thiol group-containing silane coupling agent in an acidic medium, thereby covalently bonding the mercapto group-containing silane coupling agent to the surface of the silica dioxide particles . Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and the like. Thereafter, an appropriate amount of hydrogen peroxide is further added and sufficiently left to obtain silica abrasive grains having a group capable of forming a sulfonate on the surface. In addition, the electrokinetic potential of the silica abrasive particles can be adjusted by appropriately increasing or decreasing the amount of the mercapto group-containing silane coupling agent added.

The component preferably has a permanent negative charge of -20 mV or less, and more preferably has a permanent negative charge of -25 mV or less. In the case of silicon dioxide abrasive grains having permanently negative charges below the above value, the component (A) has high dispersion characteristics, and in particular, the polishing rate of materials containing tungsten and silicon can be improved.

The so-called "permanently negatively charged silica particles" refers to filtering the prepared aqueous dispersion of chemical mechanical polishing through a pore size of about 0.1 μm, such as Planargard NMB, manufactured by Entegris. When the filter of model PNB01010V6 was used three times, the absolute value of the electromotive potential of the silica particles before and after filtration was changed to silica particles of 5 mV or less. That is, the "silicon dioxide abrasive particles having a permanent negative charge of -20 mV or less" means that the electromotive potential before and after the third filtration is -20 mV or less, and the absolute value of the electromotive potential changes before and after filtration It is a silica abrasive grain of less than 5 mV.

The “electrostatic interaction coefficient” refers to a constant indicating the degree of attraction between the silica abrasive grains and the polishing object, and can be expressed by the following formula. (Electrostatic interaction coefficient) = (electromotive potential of the silica abrasive particles contained in the filtered chemical mechanical polishing water-based dispersion) × (electromotive potential of the surface to be polished) That is, it is considered that the electrostatic interaction coefficient is a negative sign, and the greater the absolute value thereof, the stronger the attraction force between the silica abrasive grains and the polishing target, and the polishing speed of the polishing target surface is further increased. Furthermore, the electrostatic interaction coefficient is a negative sign, and the larger the absolute value, the more difficult the aggregated particles to stay on the surface to be polished, and more effective polishing can be performed. Therefore, there is a possibility of reducing the occurrence of polishing damage such as wiring materials. Happening. Therefore, the electrostatic interaction coefficient is preferably a negative sign, and the absolute value thereof is preferably larger, particularly preferably 100 or more.

The average particle diameter of the component (A) is not particularly limited, and its lower limit is preferably 5 nm, more preferably 10 nm, and particularly preferably 15 nm, and its upper limit is preferably 300 nm, more preferably 150 nm, and particularly preferably 100 nm. If the average particle diameter of the component (A) is within the above range, there may be a case where the polishing rate of the material containing tungsten or silicon can be increased while reducing the occurrence of polishing damage in the polished surface. In the above range, if the average particle diameter of the component (A) is 10 nm or more, there are cases where the polishing rate of a material containing tungsten or silicon can be further increased. In addition, if the average particle diameter of the component (A) is 100 nm or less, there is a case where the occurrence of polishing damage in the surface to be polished can be further reduced.

The average particle diameter of the component can be determined by measuring with a particle size distribution measuring device using the dynamic light scattering method as the measuring principle. Examples of the particle diameter measuring device using the dynamic light scattering method include the dynamic light scattering type particle size distribution measuring device "LB-550" manufactured by Horiba, Ltd., and the nanometer manufactured by Beckman-Coulter. Rice particle analyzer "DelsaNano S", "Zetasizernano Zs" manufactured by Malvern, etc. In addition, the average particle diameter measured using the dynamic light scattering method represents the average particle diameter of the secondary particles formed by aggregation of a plurality of primary particles.

The lower limit of the content of the component (A) is preferably 0.05% by mass, more preferably 0.1% by mass, and particularly preferably 0.3% by mass relative to the total mass of the water-based dispersion for chemical mechanical polishing. If the content of the component (A) is equal to or higher than the lower limit, there may be a case where a sufficient polishing rate for polishing a material containing tungsten or silicon can be obtained. On the other hand, the upper limit of the content of the component (A) is preferably 10% by mass, more preferably 5% by mass, and particularly preferably 3% by mass relative to the total mass of the aqueous dispersion for chemical mechanical polishing. If the content of (A) silicon dioxide abrasive grains is equal to or less than the upper limit, storage stability tends to be good, and there may be cases where good flatness on the surface to be polished or polishing damage can be reduced.

1.2 (B) Metal nitrate and metal sulfate The chemical mechanical polishing aqueous dispersion of this embodiment contains (B) at least one selected from the group consisting of metal nitrate and metal sulfate. The water-based dispersion of chemical mechanical polishing of the present embodiment contains the component (B), and the surface of the surface to be polished is oxidized to form a fragile modified layer, so that the polishing rate can be increased. In particular, the grinding speed of materials containing tungsten or silicon can be increased.

Specific examples of the component (B) include metal nitrates such as copper nitrate, cobalt nitrate, zinc nitrate, manganese nitrate, iron nitrate, molybdenum nitrate, bismuth nitrate, and cerium nitrate; copper sulfate, cobalt sulfate, zinc sulfate, and sulfuric acid Metal sulfates such as manganese, ferric sulfate, and silver sulfate. Among these, copper nitrate, ferric nitrate, copper sulfate, and ferric sulfate are preferred, ferric nitrate and ferric sulfate are more preferred, and ferric nitrate is particularly preferred. In particular, ferric nitrate has a high oxidizing power in metal nitrate, so it is easy to effectively oxidize materials containing tungsten or silicon to form a fragile modified layer, thereby improving the polishing speed of these materials.

The lower limit of the content of the component (B) is preferably 0.001% by mass, more preferably 0.01% by mass, and particularly preferably 0.05% by mass relative to the total mass of the water-based dispersion for chemical mechanical polishing. On the other hand, the upper limit of the content of the component (B) is preferably 1% by mass, more preferably 0.5% by mass, and particularly preferably 0.15% by mass with respect to the total mass of the aqueous dispersion for chemical mechanical polishing. If the content of the component (B) is within the above range, the effect of oxidizing the surface of the surface to be polished to form a fragile modified layer is sufficiently obtained, and therefore the polishing rate can be increased. In addition, by suppressing excessive polishing, the occurrence of polishing damage of wiring materials and the like may be reduced.

1.3 (C) Organic acids and their salts The aqueous dispersion for chemical mechanical polishing of this embodiment contains (C) at least one selected from the group consisting of organic acids and their salts. The chemical mechanical polishing aqueous dispersion of this embodiment contains the component (C), and the component (C) is located on the surface to be polished to increase the polishing rate, and the precipitation of metal salts during polishing can be suppressed. In addition, the component (C) is located on the surface to be polished, which may reduce damage caused by etching and corrosion of the surface to be polished.

The component (C) is preferably an organic acid or a salt thereof that has coordination ability with respect to ions or atoms of elements including wiring materials. As such a component (C), an organic acid having 0 to 1 hydroxyl group and 1 to 2 carboxyl groups in one molecule is more preferred, and 0 to 1 hydroxyl group and 1 in one molecule are particularly preferred Organic acids with ~2 carboxyl groups and a first acid dissociation constant pKa of 1.5-4.5. If it is such a component (C), since the ability to locate on the surface to be polished is high, the polishing speed for the surface to be polished can be increased. In addition, such a component (C) can stabilize metal ions generated by polishing of wiring materials and the like and suppress the precipitation of metal salts. Therefore, a high degree of flatness can be obtained while suppressing the surface roughness of the surface to be polished, and can be reduced The occurrence of abrasive damage such as wiring materials.

(C) As a specific example of an organic acid among components, lactic acid, tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, malic acid, malonate Acid, glutaric acid, succinic acid, benzoic acid, p-hydroxybenzoic acid, quinolinic acid, quinalic acid, amide sulfate; glycine, alanine, aspartic acid, glutamic acid, lysine, arginine Amino acids such as acids, tryptophan, aromatic amino acids and heterocyclic amino acids. Among these, maleic acid, succinic acid, lactic acid, malonic acid, p-hydroxybenzoic acid and glycolic acid are preferred, and maleic acid and malonic acid are more preferred. (C) One component may be used alone, or two or more components may be used in combination at any ratio.

In the component (C), specific examples of the organic acid salt may be salts of the above-exemplified organic acids, or they may be reacted with a base separately added to the chemical mechanical polishing aqueous dispersion to form the organic acid. salt. Examples of such bases include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, organic bases such as tetramethyl ammonium hydroxide (TMAH), and choline. Compounds, and ammonia.

The lower limit of the content of the component (C) is preferably 0.001% by mass, more preferably 0.01% by mass, and particularly preferably 0.1% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion. On the other hand, the upper limit of the content of the component (C) is preferably 2% by mass, more preferably 1% by mass, and particularly preferably 0.5% by mass relative to the total mass of the aqueous dispersion for chemical mechanical polishing. If the content of the component (C) is within the above range, a sufficient polishing rate for the surface to be polished can be obtained, and precipitation of metal salts is suppressed, and the occurrence of polishing damage to the surface to be polished may be reduced.

1.4 (D) Water-soluble polymer The water-based dispersion for chemical mechanical polishing of the present embodiment preferably contains (D) a water-soluble polymer (hereinafter, also referred to as "(D) component"). According to the chemical mechanical polishing aqueous dispersion of the present embodiment, the component (D) is contained, and the component (D) is adsorbed on the surface to be polished and the polishing friction is reduced, which may improve flatness. In addition, when the component (D) is adsorbed on the surface of the tungsten film, the corrosion of the tungsten film may be suppressed.

Examples of the component (D) include polycarboxylic acids, polysulfonic acids, and salts of these. Specific examples of polycarboxylic acids include polyacrylic acid, polymaleic acid, and copolymers of these. Specific examples of polysulfonic acid include polystyrene sulfonic acid and the like. Among these, polysulfonic acid and its salts are preferred, and polystyrenesulfonic acid and its salts are more preferred. By using these water-soluble polymers, the compatibility with the component (B) becomes good, and in addition to the above effects, the dispersion characteristics of the chemical mechanical polishing aqueous dispersion may be good.

(D) The weight average molecular weight (Mw) of the component is preferably 1,000 or more and 1,000,000 or less, and more preferably 3,000 or more and 800,000 or less. When the weight-average molecular weight of the component (D) is within the above range, the component (D) is easily adsorbed on the surface to be polished, which may further reduce polishing friction. As a result, there are cases where the occurrence of polishing damage on the polished surface can be further reduced. In addition, the "weight average molecular weight (Mw)" in this specification means the polyethylene glycol equivalent weight average molecular weight measured by gel permeation chromatography (Gel Permeation Chromatography, GPC).

The lower limit of the content of the component (D) is preferably 0.001% by mass, and more preferably 0.005% by mass with respect to the total mass of the water-based dispersion for chemical mechanical polishing. On the other hand, the upper limit of the content of the component (D) is preferably 1% by mass, and more preferably 0.5% by mass relative to the total mass of the water-based dispersion for chemical mechanical polishing. If the content of the component (D) is within the above range, it may be adsorbed on the surface to be polished, such as a wiring material, and the flatness of the surface to be polished may be improved.

1.5 Other ingredients The water-based dispersion for chemical mechanical polishing of the present embodiment may contain oxidizing agent, surfactant, nitrogen-containing heterocyclic compound, pH adjusting agent, etc. in addition to water as the main liquid medium.

<Water> The aqueous dispersion for chemical mechanical polishing of this embodiment contains water as the main liquid medium. Water is not particularly limited, but pure water is preferred. Water may be prepared as the remaining part of the constituent material of the chemical mechanical polishing water-based dispersion, and the content of water is not particularly limited.

>oxidant> The aqueous dispersion for chemical mechanical polishing of this embodiment may contain an oxidizing agent different from the component (B). By containing such an oxidizing agent, the surface to be polished is further oxidized and a complexation reaction with the components of the polishing liquid is promoted, so that a fragile modified layer can be formed on the surface to be polished, so there is a further increase in the polishing rate Case.

Examples of such an oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, potassium hypochlorite, ozone, potassium periodate, and peracetic acid. Among these oxidants, potassium periodate, potassium hypochlorite, and hydrogen peroxide are preferred, and hydrogen peroxide is more preferred. These oxidants may be used alone or in combination of two or more.

When the chemical mechanical polishing aqueous dispersion of this 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. The mass% is more preferably 0.005 mass%, and 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 relative to the total mass of the water-based dispersion for chemical mechanical polishing. In addition, in the case where an oxidizing agent different from the component (B) is contained in the above range, an oxide film may be formed on the surface of the polished surface containing metal such as wiring materials, so it is preferable to perform CMP immediately Add an oxidizer before the grinding process.

<Surfactant> The water-based dispersion for chemical mechanical polishing of this embodiment may contain a surfactant. By containing a surfactant, there may be a case where moderate viscosity can be imparted to the chemical mechanical polishing aqueous dispersion.

The surfactant is not particularly limited, and examples thereof include anionic surfactants, cationic surfactants, and nonionic surfactants. Examples of the anionic surfactants include carboxylates such as fatty acid soaps and alkyl ether carboxylates; sulfonates such as alkylbenzene sulfonates, alkyl naphthalene sulfonates, and α-olefin sulfonates; Sulfate salts such as higher alcohol sulfate ester salts, alkyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts; fluorine-containing surfactants such as perfluoroalkyl compounds. Examples of cationic surfactants include aliphatic amine salts and aliphatic ammonium salts. 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 aqueous dispersion of this embodiment contains a surfactant, the content of the surfactant is preferably 0.001% by mass to 5% by mass relative to the total mass of the chemical mechanical polishing aqueous dispersion, and more preferably It is 0.001% by mass to 3% by mass, and particularly preferably 0.01% by mass to 1% by mass.

<Nitrogen-containing heterocyclic compound> The water-based dispersion for chemical mechanical polishing of this embodiment may contain a nitrogen-containing heterocyclic compound. By containing the nitrogen-containing heterocyclic compound, there are cases where excessive etching of the wiring material can be suppressed and roughness of the surface after polishing can be prevented.

In this specification, the "nitrogen-containing heterocyclic compound" refers to an organic compound containing at least one heterocyclic ring selected from a hetero five-membered ring and a hetero six-membered ring having at least one nitrogen atom. Examples of the heterocyclic ring include hetero five-membered rings such as pyrrole structure, imidazole structure, and triazole structure; hetero six-membered rings such as pyridine structure, pyrimidine structure, pyridazine structure, and pyrazine structure. These heterocycles can form fused rings. Specific examples include indole structure, isoindole structure, benzimidazole structure, benzotriazole structure, quinoline structure, isoquinoline structure, quinazoline structure, cinnoline structure, phthalazine structure, quinoline Oxoline structure, acridine structure, etc. Among the heterocyclic compounds having such a structure, a heterocyclic compound having a pyridine structure, a quinoline structure, a benzimidazole structure or a benzotriazole structure is preferred.

Specific examples of nitrogen-containing heterocyclic compounds include aziridine, pyridine, pyrimidine, pyrrolidine, pyridine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benziso Quinoline, purine, pteridine, triazole, triazolidine, benzotriazole, carboxybenzotriazole and the like, and further derivatives having these skeletons can be cited. Among these, benzotriazole, triazole, imidazole, and carboxybenzotriazole are preferable. One type of these nitrogen-containing heterocyclic compounds may be used alone, or two or more types may be used in combination.

In the case where the chemical mechanical polishing aqueous dispersion contains a nitrogen-containing heterocyclic compound, the content of the nitrogen-containing heterocyclic compound is preferably 0.05% by mass to 2 masses relative to the total mass of the chemical mechanical polishing aqueous dispersion. % Is more preferably 0.1% by mass to 1% by mass, and particularly preferably 0.2% by mass to 0.6% by mass.

<pH adjuster> The water-based dispersion for chemical mechanical polishing of the present embodiment may contain a pH adjusting agent to adjust the pH to 1 or more and 6 or less. Examples of the pH adjuster include alkalis such as potassium hydroxide, ethylenediamine, TMAH (tetramethylammonium hydroxide), and ammonia, and one or more of these can be used.

1.6 pH The pH value of the chemical mechanical polishing aqueous dispersion of this embodiment is 1 or more and 6 or less, preferably 1 or more and 5 or less, more preferably 1 or more and 4.2 or less, still more preferably 1 or more and 3.5 or less, and particularly preferably 1.5 or more and 3 or less. If the pH value is in the above range, the surface potential of the material containing tungsten or silicon can be set to positive. Therefore, the component (A) preferentially polishes the material containing tungsten or silicon, thereby improving the polishing rate. In addition, if the pH value is within the above range, the surface roughness or corrosion of the tungsten film can be suppressed.

In addition, the pH of the chemical mechanical polishing aqueous dispersion of the present embodiment can be adjusted by appropriately increasing or decreasing the amounts of the components (B), (C), and the pH adjuster.

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

1.7 Purpose The water-based dispersion for chemical mechanical polishing of the present embodiment is a suitable composition for high-speed polishing of a substrate having at least any one of a wiring material, an insulating film material, and a barrier metal material on the surface to be polished, wherein tungsten is included for polishing It is especially suitable for silicon materials such as silicon dioxide. Therefore, the water-based dispersion for chemical mechanical polishing of the present embodiment is suitable as an abrasive for chemical mechanical polishing of a surface to be polished having tungsten as a wiring material and silicon nitride or silicon dioxide as an insulating film material. That is, it is suitable for a tungsten plug and interconnection process in which tungsten other than wiring is removed and the interlayer insulating film surrounding tungsten as wiring is simultaneously chemically mechanically polished.

In the chemical mechanical polishing, for example, a polishing device 100 as 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 (water-based dispersion for chemical mechanical polishing) 44 from the slurry supply nozzle 42 and rotating the turntable 48 to which the polishing cloth 46 is attached while rotating the turntable 48 The carrier head 52 of 50 abuts. In addition, FIG. 1 also shows the water supply nozzle 54 and the dresser 56 together.

The grinding load of the carrier head 52 can be selected in the range of 0.7 psi to 70 psi, preferably 1.5 psi to 35 psi. In addition, the number of revolutions of the turntable 48 and the carrier head 52 can be appropriately selected within the range of 10 rpm to 400 rpm, and preferably 30 rpm to 150 rpm. The flow rate of the slurry (water-based dispersion for chemical mechanical polishing) 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 apparatuses include: models "EPO-112" and "EPO-222" manufactured by Ebara Manufacturing Co., Ltd.; models "LGP-510" and "LGP" manufactured by lapmaster SFT. -552"; Models "Mirra" and "Reflexion" manufactured by Applied Material; Model "POLI-400L" manufactured by G&P Technology; AMAT The model manufactured by the company is "Reflexion LK"; the model manufactured by FILTEC is "FLTec-15" and so on.

2. Examples Hereinafter, the present invention will be described using examples, but the present invention is not limited by these examples. In addition, unless otherwise indicated, "part" and "%" in this Example are quality standards.

2.1 Preparation of silicon dioxide particle dispersion <Preparation of Silicon Dioxide Particle Dispersion A> The silica particle dispersion A is prepared as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20% by mass, average particle diameter 75 nm) and 3-mercaptopropyl group manufactured by Fuso Chemical Industry Co., Ltd. 6 g of trimethoxysilane was mixed and heated under reflux for 2 hours, thereby obtaining a thiolated silica sol. Hydrogen peroxide was added to the silica sol and heated to reflux for 8 hours, thereby oxidizing the surface of the silica particles and fixing the sulfonic acid groups. In this way, a silica dioxide particle dispersion A having a silica concentration of 20% by mass in solid content and an average particle diameter of 73 nm was obtained.

<Preparation of Silicon Dioxide Particle Dispersion B> The silicon dioxide particle dispersion B is produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-1; silica content (solid content concentration) 12% by mass, average particle diameter 35 nm) and 3-mercaptopropyl group manufactured by Fuso Chemical Industry Co., Ltd. 6 g of trimethoxysilane was mixed and heated under reflux for 2 hours, thereby obtaining a thiolated silica sol. Hydrogen peroxide was added to the silica sol and heated to reflux for 8 hours, thereby oxidizing the surface of the silica particles and fixing the sulfonic acid groups. In this way, a silica particle dispersion B having a silica concentration of 12% by mass in solid content and an average particle diameter of 36 nm was obtained.

<Preparation of silica particle dispersion C> The silicon dioxide particle dispersion C is produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-7; silica content (solid content concentration) 22% by mass, average particle diameter 120 nm) and 3-mercaptopropyl group manufactured by Fuso Chemical Industry Co., Ltd. 6 g of trimethoxysilane was mixed and heated under reflux for 2 hours, thereby obtaining a thiolated silica sol. Hydrogen peroxide was added to the silica sol and heated to reflux for 8 hours, thereby oxidizing the surface of the silica particles and fixing the sulfonic acid groups. In this way, a silicon dioxide particle dispersion C having a silicon dioxide concentration of 22% by mass in solid content and an average particle diameter of 117 nm was obtained.

<Preparation of Silicon Dioxide Particle Dispersion D> Based on the manufacturing method described in Japanese Patent Publication No. 2017-514295, the silica particle dispersion D was prepared as follows. A dispersion containing 1% by mass of colloidal silica and 0.004% by mass of tetrabutylammonium hydroxide was prepared. A concentrated colloid with an average particle size of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20% by mass, average particle diameter 75 nm) manufactured by Fuso Chemical Industry Co., Ltd. The silica dispersion was mixed with tetrabutylammonium hydroxide and water to obtain a surface-treated tetrabutylammonium hydroxide with a silica concentration of 20% by mass and a mean particle diameter of 75 nm Silicon dioxide particle dispersion D.

<Preparation of Silicon Dioxide Particle Dispersion E> Based on the manufacturing method described in Japanese Patent Publication No. 2017-514295, the silica particle dispersion E was prepared as follows. A dispersion containing 1% by mass of colloidal silica and 0.004% by mass of 3-(aminopropyl)trimethoxysilane was prepared. A concentrated colloid with an average particle size of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20% by mass, average particle diameter 75 nm) manufactured by Fuso Chemical Industry Co., Ltd. The silicon dioxide dispersion is mixed with 3-(aminopropyl)trimethoxysilane and water, thereby obtaining the surface concentration of 3-(aminopropyl)trimethoxysilane, the concentration of silicon dioxide is the solid concentration 20% by mass of silica particle dispersion E with an average particle diameter of 75 nm.

2.2 Preparation of aqueous dispersion of chemical mechanical grinding Each component is added to a polyethylene container so as to have the composition shown in Table 1 or Table 2 below, and then potassium hydroxide is added as necessary, so as to have a pH value shown in Table 1 or Table 2 below After adjustment, pure water was added so that the total amount of all components became 100 parts by mass, thereby obtaining a chemical mechanical polishing water-based dispersion used in each example and each comparative example.

In addition, the surface charge of the abrasive particles contained in the obtained chemical mechanical polishing water-based dispersion was measured using an ultrasonic-type particle size distribution·electric potential measuring device (Model "DT-1200" manufactured by Dispersion Technology). (Hereinafter referred to as "electric potential before filtering"). The results are shown in Table 1 and Table 2 below.

Furthermore, the obtained chemical mechanical polishing aqueous dispersion was passed through a filter of Planargard NMB filter model PNB01010V6 with a pore size of about 0.1 μm manufactured by Entegris, three times. The surface of the abrasive particles contained in the water-based dispersion of the chemical mechanical polishing thus passed through the tertiary filter was measured using an ultrasonic-type particle size distribution·electric potential measuring device (Model "DT-1200" manufactured by Dispersion Technology). Charge (hereinafter referred to as "filtered electromotive potential"). The results are shown in Table 1 and Table 2 below.

2.3 Evaluation method 2.3.1 Evaluation of grinding speed Using the prepared chemical mechanical polishing aqueous dispersion, a 12-inch diameter wafer with a 500 nm tungsten film and a 12-inch diameter wafer with a 2000 nm silicon oxide film were used as the object to be polished. Under the conditions, a 60 second chemical mechanical polishing test was conducted.

<Grinding conditions> ·Grinding device: Model "POLI-400L" manufactured by G&P Technology ·Abrasive pad: "IC1000" manufactured by Nitta Haas ·Supply speed of water dispersion for chemical mechanical grinding: 100 mL/min ·Rotating speed of platform: 100 rpm ·Head rotation: 90 rpm ·Head pressure: 2 psi ·Polishing speed (nm/min)=(Thickness of film before polishing-Thickness of film after polishing)/Polishing time

In addition, the thickness of the tungsten film is measured by a resistivity measuring machine (model "Σ-5" manufactured by NPS) and the DC four-probe method, based on the sheet resistance value and the volume of tungsten. The resistivity is calculated by the following formula. Thickness of film (Å) = [volume resistivity of tungsten film (Ω·m) ÷ surface resistance value (Ω)] × 10 ¹⁰

On the other hand, the thickness of the silicon oxide film was measured using an optical interference film thickness meter "F20 Film Thickness Measurement System" manufactured by Filmetrics (filmetrics) Co., Ltd.

The evaluation criteria of the polishing rate are as follows. The polishing rates of the tungsten film and the silicon oxide film and their evaluation results are shown in Table 1 and Table 2 below. (Evaluation criteria for tungsten film polishing speed) ·When the polishing rate is 100 Å/min or more, the polishing rate is high, so in actual semiconductor polishing, it is easy to ensure the speed balance with the polishing of other material films and it is practical, so it is judged as good and expressed as "○" . -When the polishing rate is less than 100 Å/min, the polishing rate is small, so it is difficult to be practical, and it is judged as defective and expressed as “×”. (Evaluation criteria for polishing speed of silicon oxide film) ·When the polishing rate is 300 Å/min or more, the polishing rate is high. Therefore, in actual semiconductor polishing, it is easy to ensure the speed balance with the polishing of other material films and is practical. Therefore, it is judged as good and expressed as "○" . -When the polishing rate is less than 300 Å/min, the polishing rate is small, so it is difficult to be practical, and it is judged as defective and expressed as “×”.

2.3.2 Defect evaluation The silicon oxide film-bearing wafer with a diameter of 12 inches as the object to be polished was polished for 1 minute under the following conditions. <Grinding conditions> ·Grinding device: Model "Reflexion LK" manufactured by AMAT ·Abrasive pad: "IC1000" manufactured by Nitta Haas ·Supply speed of water dispersion for chemical mechanical grinding: 300 mL/min ·Rotating speed of platform: 100 rpm ·Head rotation: 90 rpm ·Head pressure: 2 psi

For wafers with silicon oxide films that have been polished as described above, use a defect inspection device (Model "Surfscan SP1" manufactured by KLA-Tencor), for sizes greater than 90 nm The total number of defects is counted. The evaluation criteria are as follows. The total number of defects for each wafer and their evaluation results are shown in Table 1 and Table 2 below. (Evaluation criteria) -The case where the total number of defects per wafer is less than 500 is judged to be good, and is described as "○" in the table. -A case where the total number of defects per wafer is 500 or more is judged to be defective, and is indicated as "×" in the table.

2.3.3 Coefficient of electrostatic interaction An electromotive potential measuring device for solid surface analysis using a flowing current method (Model "Surpass 3" manufactured by Anton Paar) was used to measure the electromotive potential on the surface of the silicon oxide film. The silicon oxide film-attached wafer was attached to the measurement cell, and the flow current change when the flow pressure was changed from 600 mbar to 200 mbar was converted into electrokinetic potential. As the internal liquid at the time of measurement, the abrasive particles of the chemical mechanical polishing aqueous dispersion were removed by centrifugal separation, and the obtained supernatant was used for measurement.

Then, the constant indicating the degree of attraction between the abrasive particles and the silicon oxide film, that is, the product of the electromotive potential of the filtered chemical mechanical polishing aqueous dispersion and the electromotive potential on the surface of the silicon oxide film is defined as the electrostatic interaction coefficient, and shows In Table 1 and Table 2 below. It can be considered that the electrostatic interaction coefficient is a negative sign, and the greater the absolute value, the easier the abrasive particles and the silicon oxide film are in contact, and the easier the polishing speed is increased.

2.4 Evaluation results The following Table 1 and Table 2 show the composition and evaluation results of the chemical-mechanical polishing water-based dispersion of each example and each comparative example.

[Table 1]

[Table 2]

Each component in Table 1 and Table 2 uses the following commercial products or reagents, respectively. <Abrasive grains> • Silicon dioxide particle dispersion A to silicon dioxide particle dispersion E: prepared separately from the above. <Metal nitrate, etc.> ·Ferric nitrate: the trade name "iron(III) nitrate nonahydrate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. ·Iron sulfate: The trade name "iron(III) sulfate n hydrate" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. <Water-soluble polymer> ·Sodium polystyrene sulfonate: Tosoh fine chemical (Tosoh finechem) company trade name "Polinas (Polinas) PS-1", weight average molecular weight (Mw) = 10,000 ·Polycarboxylic acid: Trade name "Jurymer AC-10L" manufactured by East Asia Synthetic Company, polyacrylic acid, weight average molecular weight (Mw) = 50,000 <Organic acid> ·Maleic acid: trade name "maleic acid" manufactured by Shiquan Chemical Company ·Malonic acid: the trade name "malonic acid" manufactured by Fusang Chemical Industry Company <Other additives> ·Nitric acid: trade name "Nitric acid" manufactured by Fujifilm Wako Pure Chemicals Co., Ltd. and inorganic acid · Potassium hydroxide: pH adjuster manufactured by Kanto Chemical Co., Ltd.

According to the chemical-mechanical polishing aqueous dispersions of Examples 1 to 9, it is known that by containing silica dioxide abrasive particles having a group capable of forming a sulfonate on the surface, metal nitrate or metal sulfate, and an organic acid , Can grind tungsten film and silicon oxide film at high speed, and can reduce the occurrence of surface defects on the polished surface. In addition, in the chemical mechanical polishing aqueous dispersions of Examples 1 to 9, the silica particle dispersion A, the silica particle dispersion B, and the silica particle dispersion C have a permanent negative charge. Since the surface potential of the silicon oxide film is positive, the electrostatic interaction coefficient as the product shows a large value with a negative sign.

The chemical mechanical polishing aqueous dispersion of Comparative Example 1 contains silicon dioxide particle dispersion D surface-treated with tetrabutylammonium hydroxide as abrasive particles. In this case, neither the tungsten film nor the silicon oxide film can be polished at high speed. In addition, it was found that by using the chemical mechanical polishing aqueous dispersion containing the silica particle dispersion D, a large amount of surface defects on the surface to be polished were also generated.

The aqueous dispersion for chemical mechanical polishing of Comparative Example 2 contains silicon dioxide particle dispersion E surface-treated with 3-(aminopropyl)trimethoxysilane as abrasive particles. In this case, the silicon oxide film cannot be polished at high speed. It is considered that the reason is that the surface potential of the abrasive grains and the surface potential of the surface to be polished are both positive, and a strong repulsive force acts. In addition, it was found that by using the chemical-mechanical polishing aqueous dispersion containing the silica particle dispersion E, a large amount of surface defects on the surface to be polished were also generated.

Since the water-based dispersion for chemical mechanical polishing of Comparative Example 3 does not contain the component (B), the surface to be polished cannot be oxidized, so neither the tungsten film nor the silicon oxide film can be polished at high speed.

The chemical mechanical polishing aqueous dispersion of Comparative Example 4 contains nitric acid as an inorganic acid instead of the component (C). In this case, the surface to be polished is rough due to nitric acid, which is a strong acid, and a large number of surface defects are generated.

The aqueous dispersions of chemical mechanical polishing of Comparative Examples 5 and 6 are not only negatively charged on the surface of the silica abrasive grains, but also negatively charged on the surface of the silicon oxide film due to the liquidity being alkaline, so the action has a strong repulsion, so High speed grinding is not possible.

From the above results, it is known that the chemical mechanical polishing composition of the present invention can polish the tungsten film and the silicon oxide film at high speed, and can reduce the occurrence of surface defects on the surface to be polished.

The present invention is not limited to the above-mentioned embodiment, and various modifications are possible. For example, the present invention includes substantially the same structure as the structure described in the embodiment (for example, a structure having the same function, method, and result, or a structure having the same purpose and effect). In addition, the present invention includes a configuration in which non-essential parts of the configuration described in the embodiment are replaced. In addition, the present invention includes a structure that exhibits the same operational effects as those described in the embodiments or a structure that can achieve the same purpose. In addition, the present invention includes a configuration obtained by adding a known technique to the configuration described in the embodiments.

42‧‧‧Slurry supply nozzle 44‧‧‧Slurry (water dispersion of chemical mechanical grinding) 46‧‧‧Grinding 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 device.

42‧‧‧Slurry supply nozzle

44‧‧‧Slurry (water dispersion of chemical mechanical grinding)

46‧‧‧Grinding cloth

48‧‧‧Turntable

50‧‧‧ substrate

52‧‧‧Carrying head

54‧‧‧Water supply nozzle

56‧‧‧ Dresser

100‧‧‧grinding device

Claims (7)

An aqueous dispersion for chemical mechanical grinding, containing: (A) Silicon dioxide abrasive particles, which have a group capable of forming sulfonate on the surface; (B) at least one selected from the group consisting of metal nitrate and metal sulfate; and (C) at least one selected from the group consisting of organic acids and their salts, And the pH value of the chemical mechanical polishing aqueous dispersion is 1 or more and 6 or less. The aqueous dispersion for chemical mechanical polishing as described in item 1 of the patent application scope further contains (D) a water-soluble polymer. The chemical mechanical polishing aqueous dispersion as described in item 1 of the patent application scope, wherein the (A) silicon dioxide abrasive particles have a permanent negative charge of -20 mV or less. The chemical mechanical polishing water-based dispersion as described in item 2 of the patent application scope, wherein the (A) silicon dioxide abrasive particles have a permanent negative charge of -20 mV or less. The chemical mechanical polishing water-based dispersion according to any one of items 1 to 4 of the patent application range has a negative sign of the electrostatic interaction coefficient with the object to be polished. The water-based dispersion for chemical mechanical polishing as described in any one of the first to fourth patent application scopes is for silicon-containing substrate polishing. The aqueous dispersion for chemical mechanical polishing as described in item 6 of the patent application range, wherein the silicon-containing substrate has tungsten.

Images