阅读说明：本技术 金属研磨用胶态二氧化硅 (Colloidal silica for metal polishing ) 是由 杉山大介 中野智阳 于 2020-04-14 设计创作，主要内容包括：本发明的课题在于提供一种能够实现高研磨速度的金属研磨用胶态二氧化硅。上述课题能够通过金属研磨用胶态二氧化硅来解决,该金属研磨用胶态二氧化硅含有：包含至少1个羧基的官能团通过共价键固定于表面所得到的二氧化硅颗粒。(The invention provides colloidal silica for metal polishing, which can realize high polishing speed. The above problems can be solved by colloidal silica for metal polishing, which contains: a silica particle obtained by immobilizing a functional group comprising at least 1 carboxyl group on the surface by a covalent bond.)

1. A colloidal silica for metal polishing, characterized by comprising:

a silica particle obtained by immobilizing a functional group comprising at least 1 carboxyl group on the surface by a covalent bond.

2. The colloidal silica of claim 1, wherein:

the silica particles have a group represented by the following formula (1) on the surface,

in the formula, R¹Is an organic functional group having at least 1 carboxyl group, R²And R³Identically OR differently hydrogen atoms, hydrocarbon radicals OR-OR⁴Wherein R is⁴Is a hydrogen atom, a hydrocarbon group or a silicon-containing group.

3. Colloidal silica according to claim 1 or 2, characterized in that:

the silica particles are surface-modified with a silane coupling agent having a functional group containing at least 1 carboxyl group or a precursor group thereof or a hydrolysis condensate thereof.

4. The colloidal silica according to any one of claims 1 to 3, wherein:

the metal is a transition metal.

5. The colloidal silica of claim 4, wherein:

the transition metal is at least one selected from cobalt, ruthenium, copper, tungsten, tantalum and titanium.

Technical Field

The present invention relates to colloidal silica for metal polishing.

Background

Colloidal silica is a substance in which silica particles are dispersed in a medium such as water, and is used as a polishing agent for semiconductor wafers and the like.

For example, jp 2010-41029 a (patent document 1) describes an aqueous dispersion for chemical mechanical polishing, which contains: silica particles having defined chemical properties; and an organic acid having 2 or more carboxyl groups. Patent document 1 describes, as effects of organic acids: (1) prevent metal precipitation by coordinating with metal ions such as copper, tantalum, titanium, etc. dissolved into the aqueous dispersion by grinding; (2) the polishing speed of the polishing objects such as copper films, barrier metal films, TEOS films and the like is improved; (3) coordinating with sodium ion or potassium ion which is pulverized and eluted from the silica particles during grinding, and preventing the sodium ion or potassium ion from being adsorbed to the surface to be ground; (4) adsorbing to the surface of the silica particles, and improving the dispersion stability of the silica particles.

Further, Japanese patent application laid-open No. 2016-30831 (patent document 2) discloses a polishing composition for Chemical Mechanical Polishing (CMP) of a cobalt-containing substrate, which comprises a predetermined amount of a polishing agent such as colloidal silica and at least 2 kinds of specific chelating agents, and the balance of the polishing composition is substantially deionized water and has a pH of 2.0 to 12. Patent document 2 describes: by combining 2 chelating agents, a high cobalt removal rate is imparted compared to when one chelating agent is used alone.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2010-41029

Patent document 2: japanese patent laid-open publication No. 2016-30831

Disclosure of Invention

Technical problem to be solved by the invention

In metal polishing, it is required to further increase the polishing rate than that achieved by the polishing compositions of patent documents 1 and 2.

The purpose of the present invention is to provide colloidal silica for metal polishing that can achieve a high polishing rate.

Technical solution for solving technical problem

The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have found that a high polishing rate can be obtained by polishing a metal with colloidal silica containing silica particles in which a functional group having at least 1 carboxyl group is fixed to the surface by a covalent bond, and have further made extensive studies based on the finding, thereby completing the present invention.

That is, the present invention includes the following aspects.

Item 1. a colloidal silica for metal polishing, which contains: a silica particle obtained by immobilizing a functional group comprising at least 1 carboxyl group on the surface by a covalent bond.

The colloidal silica of item 1, wherein: the silica particles have a group represented by the following formula (1) on the surface.

[ in the formula, R¹Is an organic functional group having at least 1 carboxyl group, R²And R³Identically OR differently hydrogen atoms, hydrocarbon radicals OR-OR⁴(R⁴Is a hydrogen atom, a hydrocarbon group or a silicon-containing group. ).]

The colloidal silica of item 1 or 2, wherein: the silica particles are surface-modified with a silane coupling agent having a functional group containing at least 1 carboxyl group or a precursor group thereof or a hydrolysis condensate thereof.

The colloidal silica according to any one of items 1 to 3, wherein: the metal is a transition metal.

The colloidal silica of item 4, wherein: the transition metal is at least one selected from the group consisting of cobalt, ruthenium, copper, tungsten, tantalum, and titanium.

Effects of the invention

By polishing a metal with the colloidal silica of the present invention, a high polishing rate can be obtained. In addition, the colloidal silica of the present invention can realize a high metal polishing rate even when the concentration of the silica particles in the polishing composition is low.

Drawings

FIG. 1 is a graph showing the relationship between pH and Zeta potential of colloidal silica of examples and comparative examples.

Detailed Description

The colloidal silica for metal polishing of the present invention contains silica particles in which a functional group having at least 1 carboxyl group is fixed to the surface by a covalent bond (hereinafter, referred to as "surface-modified silica particles"). The functional group is preferably an organic functional group containing at least 1 carboxyl group, and more preferably a hydrocarbon group having at least 1 carboxyl group. The number of carboxyl groups contained in the functional group is preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 to 2. The position of the carboxyl group may be the terminal of the functional group or a position other than the terminal, but preferably at least 1 carboxyl group is present at the terminal.

The surface-modified silica particles are, for example, silica particles in which hydrogen atoms of hydroxyl groups (silanol groups) on the surface are substituted with a functional group containing at least 1 carboxyl group.

That is, the surface-modified silica particles have, for example, the formula: -OR (wherein R is a functional group comprising at least 1 carboxyl group.) OR a silica particle comprising a group represented by (a) OR (b). Wherein the oxygen atom in the-OR is bonded to a silicon atom inside the silica particle.

the-OR is not particularly limited, but is typically a group represented by the following formula (1).

[ in the formula, R¹Is an organic functional group having at least 1 carboxyl group, R²And R³Identically OR differently hydrogen atoms, hydrocarbon radicals OR-OR⁴(R⁴Is a hydrogen atom, a hydrocarbon group or a silicon-containing group. ).]

As R¹Examples of the organic functional group in (2) include a hydrocarbon group and a heteroatom-containing hydrocarbon group.

Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group.

Examples of the alkyl group include C such as methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl, sec-butyl, tert-butyl), pentyl and hexyl_1－12An alkyl group.

Examples of the cycloalkyl group include C such as cyclopentyl and cyclohexyl_5－12A cycloalkyl group.

Examples of the aryl group include C such as phenyl and naphthyl_6－12And (4) an aryl group.

Examples of the aralkyl group include C such as benzyl and phenethyl_6－12Aryl radical C_1－4An alkyl group.

The heteroatom-containing hydrocarbon group is preferably a hydrocarbon group containing at least one heteroatom selected from an oxygen atom, a sulfur atom and a nitrogen atom, and examples thereof include an oxygen-containing alkyl group (e.g., an alkoxy group or an alkoxyalkyl group), a sulfur-containing alkyl group (e.g., an alkylthioalkyl group), a nitrogen-containing alkyl group (e.g., a monoalkylaminoalkyl group or a dialkylaminoalkyl group), an oxygen-containing heterocyclic group (e.g., an oxygen-containing aromatic heterocyclic group such as furan or benzofuran), a sulfur-containing heterocyclic group (e.g., an oxygen-containing aromatic heterocyclic group such as thiophene or benzothiophene), and a nitrogen-containing heterocyclic group (e.g., a nitrogen-containing aromatic heterocyclic group such as pyrrole, pyridine, indole or quinoline). In the hydrocarbon group containing a hetero atom, the number of hetero atoms is preferably 1 to 3, and more preferably 1 or 2.

As R¹Preferably, the alkyl group has at least 1 carboxyl group, the alkoxy alkyl group has at least 1 carboxyl group, the alkyl thioalkyl group has at least 1 carboxyl group, or the alkyl aminoalkyl group has at least 1 carboxyl group, more preferably these groups have 1 to 4 carboxyl groups, still more preferably 1 to 3 carboxyl groups, and most preferably 1 to 2 carboxyl groups.

R²～R⁴Among them, as the hydrocarbon groupBy way of example with R¹The same groups as the hydrocarbon groups exemplified as the organic functional groups in (1) are preferably alkyl groups, more preferably C_1－4An alkyl group.

R⁴Among them, the silicon-containing group may be a group formed by reacting with another silanol group present on the surface or a group in which a hydrogen atom thereof is substituted with a functional group containing at least 1 carboxyl group, or may be a group formed by reacting with a silane coupling agent (for example, a silane coupling agent exemplified as a surface modifying agent described later).

The surface-modified silica particles are preferably silica particles surface-modified with a compound having a functional group containing at least 1 carboxyl group or a precursor group thereof (hereinafter referred to as "surface modifier").

Examples of the precursor group of the carboxyl group include a carboxylate group (e.g., a carboxylic acid alkyl ester group such as a methyl carboxylate or an ethyl carboxylate) and a carboxylic anhydride group.

Examples of the at least 1 carboxyl group or its precursor group include 1 carboxyl group, 1 carboxylate group, 2 carboxyl groups, 1 carboxylic anhydride group and 2 carboxylate groups.

The surface modifying agent generally has a reactive group capable of reacting with a hydroxyl group (silanol group) on the surface of the silica particle, and is typically a silane coupling agent or a hydrolytic condensate thereof.

Examples of the silane coupling agent include compounds represented by the following formula (2).

(in the formula, Q¹Is a hydrogen atom or a hydrocarbon group, R⁵And R⁶Identically OR differently hydrogen atoms, hydrocarbon radicals OR-OR⁷(R⁷Is a hydrogen atom or a hydrocarbon group. ) R is¹As described above. )

As Q¹And R⁵～R⁷The hydrocarbyl group shown may be enumerated as R¹The organic functional group in (2) is the same as the hydrocarbon group exemplified above. As Q¹And R⁵～R⁷Preferably an alkyl group, more preferably C_1－4An alkyl group.

The silane coupling agent is preferably a compound represented by the following formula (3).

(in the formula, R⁸Is C having 1 to 3 carboxyl groups_1－6Alkyl, C having 1 to 3 carboxyl groups_1－6Alkoxy radical C_1－6Alkyl, C having 1 to 3 carboxyl groups_1－6Alkylthio of C_1－6Alkyl, or mono-or di-C having 1 to 3 carboxyl groups_1－6Alkylamino radical C_1－6Alkyl radical, Q²～Q⁴Identically or differently hydrogen atoms or C_1－4An alkyl group. )

The silane coupling agent is more preferably a (tri-C) compound having at least 1 carboxyl group or a precursor group thereof, such as 3- (trimethoxysilyl) propylsuccinic anhydride or a hydrolysate thereof, 3- (triethoxysilyl) propylsuccinic anhydride or a hydrolysate thereof_1－4Alkoxysilyl) C_1－6An alkane or a hydrolysate thereof; silane coupling agents described in Japanese patent laid-open Nos. 2000-336093, 2013-116872, and International publication No. 2018/210711.

The silane coupling agent or a hydrolysis condensate thereof may be combined with another silane coupling agent or a hydrolysis condensate thereof. Examples of the other silane coupling agent include alkylsilanes (e.g., methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane), phenylsilanes (e.g., phenyltrimethoxysilane, phenyltriethoxysilane), mercaptoalkylsilanes (e.g., 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane), and the like. These can be used alone or in combination of two or more.

From the viewpoint of further increasing the polishing rate, the amount of carboxyl groups on the surface of the surface-modified silica particles is preferably 0.05 atomic% or more, and more preferably 0.07 atomic% or more. From the viewpoint of dispersion stability in a solvent, the amount of carboxyl groups on the surface of the surface-modified silica particles is preferably 0.5 atomic% or less, and more preferably 0.3 atomic% or less.

In the present specification, the amount of carboxyl groups on the surface of the surface-modified silica particles was measured by an X-ray photoelectron spectroscopy method under the following conditions using a sample obtained by centrifuging colloidal silica at 77,000G at 5 ℃ for 90 minutes, drying the obtained precipitate at 60 ℃ for 12 hours, then pulverizing the dried precipitate, and drying the dried precipitate at 60 ℃ under reduced pressure for 2 hours.

Measurement machine: K-Alpa + irradiation X-ray and Single Crystal spectroscopic Al Ka manufactured by Thermo Fisher Scientific Co., Ltd

X-ray spot diameter: 400 μm

Wherein the ratio of states having bond energies of 289.4 to 289.8eV is calculated as the amount of carboxyl groups on the particle surface using a value normalized with the bond energy of C-C, C-H being 284.6 eV. The state ratio is calculated using a Relative Sensitivity Factor (RSF) attached to the apparatus.

The Zeta potential of the colloidal silica is, for example, preferably from-60 to-10 mV, more preferably from-55 mV to-15 mV, and particularly preferably from-50 mV to-20 mV, at a pH of 4.

In the colloidal silica, the difference between the Zeta potential at pH 3 and the Zeta potential at pH 6 is preferably 20mV or more, more preferably 40mV or more, and particularly preferably 60mV or more.

In the present specification, the Zeta potential of colloidal silica can be measured by an apparatus using the measurement principle of the ultrasonic attenuation method.

The BET specific surface area of the surface-modified silica particles is, for example, 15 to 550m²Preferably 20 to 280 m/g²(iv)/g, more preferably 30 to 180m²/g。

In the present specification, the BET specific surface area can be measured using a sample obtained by heat-treating colloidal silica at 800 ℃ for 1 hour after pre-drying it on a hot plate.

From the viewpoint of further increasing the polishing rate, the average primary particle diameter of the surface-modified silica particles is preferably 5nm or more, more preferably 10nm or more, and still more preferably 15nm or more. From the viewpoint of suppressing the occurrence of damage to the metal to be polished, the average primary particle diameter of the surface-modified silica particles is preferably 200nm or less, more preferably 150nm or less, and still more preferably 100nm or less.

In the present specification, the average primary particle diameter of the surface-modified silica particles was determined to pass through 2727/BET specific surface area (m) so that the true specific gravity of silica is 2.2²Calculated as,/g).

From the viewpoint of further increasing the polishing rate, the average secondary particle diameter of the surface-modified silica particles is preferably 6nm or more, more preferably 12nm or more, and still more preferably 18nm or more. From the viewpoint of suppressing the occurrence of damage to the metal to be polished, the average secondary particle diameter of the surface-modified silica particles is preferably 400nm or less, more preferably 350nm or less, and still more preferably 300nm or less.

In the present specification, as for the average secondary particle size of the surface-modified silica particles, a sample was obtained by adding colloidal silica to a 0.05 mass% aqueous solution of Sodium Dodecyl Sulfate (SDS) and homogenizing the mixture, and the sample was used for measurement by a dynamic light scattering method ("ELSZ-2000S", manufactured by Otsuka Denshi Co., Ltd.).

From the viewpoint of further increasing the polishing rate, the association ratio of the surface-modified silica particles is preferably 1.2 or more, more preferably 1.4 or more, and still more preferably 1.6 or more. From the viewpoint of suppressing the occurrence of damage to the metal to be polished, the association ratio of the surface-modified silica particles is preferably 5.5 or less, more preferably 5.0 or less, and still more preferably 4.0 or less.

In the present specification, the association ratio of the surface-modified silica particles is calculated by the average secondary particle diameter/average primary particle diameter.

The surface-modified silica particles may be shaped particles. That is, the surface-modified silica particles preferably have a curved structure and/or a branched structure. The term "bent structure" refers to a structure in which 3 or more primary particles are combined into a single row of secondary particles and are not straight. The term "branched structure" refers to a structure in which 4 or more primary particles are combined with each other and are not in a single row (having branches).

The surface-modified silica particles preferably have a true specific gravity of 1.50 or more, more preferably 1.65 or more, and still more preferably 1.80 or more. When the lower limit of the true specific gravity is within the above range, the abrasive property of the colloidal silica of the present invention is further improved. The true specific gravity is preferably 2.30 or less, more preferably 2.20 or less, and still more preferably 2.16 or less. When the upper limit of the true specific gravity is within the above range, the occurrence of damage to the object to be polished is further reduced.

The true specific gravity can be measured by a measurement method in which the sample is dried and cured on a hot plate at 150 ℃ and then held in a furnace at 300 ℃ for 1 hour, and then measured by a liquid phase displacement method using ethanol.

Colloidal silica is a substance in which surface-modified silica particles are dispersed in a dispersion medium.

Examples of the dispersion medium include water, an organic solvent, and a mixed solvent thereof.

The organic solvent is usually a hydrophilic organic solvent, and examples thereof include alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, and 1, 4-butanediol), ketones (e.g., acetone and methyl ethyl ketone), and esters (e.g., ethyl acetate). These organic solvents can be used alone or in combination of two or more.

The dispersion medium is preferably water and/or alcohol, and more preferably water and/or methanol.

The content of the surface-modified silica particles in the colloidal silica is, for example, 0.1 to 30% by mass, preferably 0.3 to 20% by mass.

The method for producing colloidal silica containing surface-modified silica particles includes a method using a sol-gel method. The method using the sol-gel method includes, for example, the following steps:

(1) a step of preparing a mixture (hereinafter, referred to as "silica sol") containing an alkoxysilane, a base catalyst, water, and/or an organic solvent; and

(2) and a step of reacting the mixture with a compound (surface modifying agent) having a functional group containing at least 1 carboxyl group or a precursor group thereof.

< Process (1) >

Examples of the alkoxysilane include tetra-C such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane_1－8An alkoxysilane. These can be used alone or in combination of two or more. Of these, tetra C is preferred_1－4The alkoxysilane is more preferably tetramethoxysilane and/or tetraethoxysilane.

The type of the base catalyst is not particularly limited. The alkali catalyst is preferably an organic alkali catalyst containing no metal component from the viewpoint of avoiding the incorporation of metal impurities, and particularly preferably an organic alkali catalyst containing nitrogen. Examples of such an organic base catalyst include ethylenediamine, diethylenetriamine, triethylenetetramine, ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide (TMAH), tetramethylguanidine, 3-ethoxypropylamine, dipropylamine, and triethylamine. These can be used alone or in combination of two or more. Ammonia is preferred because it has an excellent catalytic action, is highly volatile, and can be easily removed in a subsequent step. From the viewpoint of increasing the true specific gravity of the silica particles, in order to prevent volatilization even if the reaction temperature is increased, it is preferable to select an organic base catalyst having a boiling point of 90 ℃ or higher, and at least one selected from tetramethylammonium hydroxide and 3-ethoxypropylamine is more preferable.

As the organic solvent, the same organic solvents as those exemplified for "colloidal silica" can be used. The organic solvent is preferably an alcohol, and more preferably methanol.

The method for producing the silica sol may be, for example, a method of mixing the respective components sequentially or simultaneously, a method of mixing a mixture of 2 or 3 kinds of alkoxysilane, a base catalyst, water or/and an organic solvent with the remaining components, or a method of mixing a mixture of 2 or 3 kinds of alkoxysilane, a base catalyst, water or/and an organic solvent with each other.

As the method for producing the silica sol, a method of mixing a first mixture containing the alkoxysilane and the organic solvent as needed with a second mixture containing the base catalyst, water and the organic solvent as needed is typical.

The content of the alkoxysilane is, for example, 70 to 100% by mass, preferably 75 to 100% by mass, based on 100% by mass of the first mixture.

The content of the alkali catalyst is, for example, 0.001 to 3.0% by mass, preferably 0.002 to 1.5% by mass, based on 100% by mass of the second mixture.

The ratio of the first mixture to the second mixture (mass ratio) is, for example, 5: 95 to 50: 50, preferably 10: 90 to 45: 55.

The mixing temperature of the first mixture and the second mixture is not particularly limited, and is, for example, 0 to 100 ℃, preferably 0 to 90 ℃.

The content of the silica particles in the silica sol is not particularly limited, and is, for example, 5 to 35% by mass, preferably 10 to 30% by mass. In order to adjust the content of the silica particles to the above range, the silica sol may be concentrated as necessary.

Further, examples of the method for producing a silica sol include Japanese patent application laid-open Nos. 2005-60217 and 2010-269985.

< Process (2) >

The step (2) may be, for example, any of the following steps (2A) and (2B).

Step (2A): a step of reacting a silica sol with a surface modifying agent having a precursor group having at least 1 carboxyl group, and converting the precursor group of the carboxyl group into a carboxyl group in the reaction product;

step (2B): a step of reacting the silica sol with a surface modifying agent having at least 1 carboxyl group (a surface modifying agent obtained by converting a precursor group of a carboxyl group into a carboxyl group).

In the step (2A) and the step (2B), the conversion from a precursor group of a carboxyl group to a carboxyl group can be carried out by a conventional method, and for example, the conversion from a carboxylate group or a carboxylic anhydride group to a carboxyl group can be carried out by hydrolysis.

Among these, the step (2B) is preferred.

As the surface modifier, the same surface modifiers as those exemplified in the "surface-modified silica particles" can be used.

The amount of the surface modifier used is, for example, 5 to 750. mu. mol, preferably 10 to 500. mu. mol, based on 1g of the silica particles before surface modification.

The mixing temperature of the silica sol and the surface modifier is, for example, 0 to 150 ℃, preferably 0 to 120 ℃, and more preferably 10 to 90 ℃.

The colloidal silica described above can be suitably used for polishing of metals. The polishing may be, for example, Chemical Mechanical Polishing (CMP). The polishing conditions may be known or conventional conditions.

The metal polishing composition is not particularly limited as long as it contains the colloidal silica, and may further contain an additive. Examples of the additive include a diluent, an oxidizing agent, a pH adjuster, an anticorrosive agent, a stabilizer, and a surfactant. These can be used alone or in combination of two or more.

The content of the surface-modified silica particles (or abrasive grains) in the metal polishing composition is, for example, 0.1 to 30% by mass, preferably 0.3 to 20% by mass, and more preferably 0.5 to 10% by mass. In the present invention, even if the content of the surface-modified silica particles is small, a high polishing rate can be achieved.

The metal to be polished is not particularly limited, and examples thereof include transition metals. The transition metal is preferably cobalt, ruthenium, copper, tungsten, tantalum, or titanium. Among these, at least one selected from cobalt, ruthenium, and copper is more preferable.

The object to be polished is usually a metal film.

By using the colloidal silica of the present invention, the polishing rate of the metal film can be increased. Further, the ratio of the polishing rate of the metal film to the polishing rate of the silicon oxide film can be increased, and the metal film can be selectively polished.

The metal may be a metal used for various purposes, and for example, a metal film for a semiconductor (for example, a metal film for electrode wiring, a barrier metal film) or the like may be used.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[ example 1]

A mixture of 1522.2g of tetramethoxysilane and 413.0g of methanol was added dropwise to a mixture of 2212.7g of pure water, 567.3g of 26 mass% aqueous ammonia and 12391g of methanol over 25 minutes while keeping the liquid temperature at 20 ℃ to obtain a silica sol-methanol dispersion 1. The obtained silica sol methanol dispersion 1 was charged under normal pressure, and the silica sol methanol dispersion 1 was added dropwise while keeping the capacity constant, to obtain a silica sol methanol dispersion 2 concentrated to a silica concentration of 20 mass%.

800g of silica sol methanol dispersion 2 was weighed in a 1L flask, 21.6g of a hydrolysate of (3-trimethoxysilylpropyl) succinic anhydride diluted with pure water to an effective component of 10 mass% was added, and 1300mL of pure water was added dropwise while keeping the volume constant in order to distill off the methanol in the dispersion to the outside of the system. Then, the reaction mixture was heated to reflux at 100 ℃ to react with a hydrolysate of (3-trimethoxysilylpropyl) succinic anhydride. The heating reflux was carried out until the total time of the solvent substitution and the heating reflux reached 24 hours, whereby colloidal silica S1 having a silica particle concentration of 19.5 mass% was obtained.

[ example 2]

To a mixed solution of 7500g of pure water and 1.93g of 3-ethoxypropylamine, 2740g of tetramethoxysilane was added dropwise over 60 minutes while keeping the liquid temperature at 85 ℃. After 15 minutes from the completion of the dropwise addition, 50.14g of 3-ethoxypropylamine was added to obtain a silica sol-methanol dispersion 3.

Tetramethoxysilane 1762.7g was added dropwise to a mixture of 5537g and 2452g of pure water and silica sol methanol dispersion 3 over 360 minutes while keeping the liquid temperature at 80 ℃ to obtain silica sol methanol dispersion 4.

The obtained silica sol methanol dispersion 4 was charged under normal pressure, and while keeping the capacity constant, the silica sol methanol dispersion 4 was added dropwise to obtain a silica sol methanol dispersion 5 concentrated to a silica concentration of 20 mass%.

900g of silica sol-methanol dispersion 5 was weighed out from a 1L flask, and 1.550g of 3-ethoxypropylamine was mixed therewith. The pH of the mixture at this time was 9.5. Then, 21.6g of a hydrolysate of (3-trimethoxysilylpropyl) succinic anhydride diluted with pure water to an effective component of 10 mass% was added, and 450mL of pure water was added dropwise while keeping the volume constant in order to distill off methanol in the dispersion to the outside of the system. Then, the reaction mixture was heated to reflux at 100 ℃ to react with a hydrolysate of (3-trimethoxysilylpropyl) succinic anhydride. The heating reflux was carried out until the total time of the solvent substitution and the heating reflux reached 24 hours, whereby colloidal silica S2 having a silica particle concentration of 20.0 mass% was obtained.

Comparative example 1

1300mL of pure water was added dropwise to the silica sol-methanol dispersion 2 described in example 1 while keeping the capacity constant so as to distill off methanol out of the system, thereby obtaining colloidal silica S3 having a silica particle concentration of 19.5 mass%.

Comparative example 2

To the silica sol methanol dispersion 2 described in example 1, 1.84g of 3-mercaptopropyltrimethoxysilane and 4.25g of 30 mass% hydrogen peroxide water were added, and 1300mL of pure water was added dropwise while keeping the volume constant so as to distill off the methanol in the dispersion to the outside of the system, thereby obtaining colloidal silica S4 having a silica particle concentration of 19.5 mass%.

Comparative example 3

Maleic acid (1.064 g) was added to colloidal silica S3 prepared in comparative example 1, thereby obtaining colloidal silica S5 containing maleic acid.

The obtained colloidal silicas of examples and comparative examples were evaluated for BET specific surface area, primary particle diameter, secondary particle diameter, association ratio, true specific gravity, and surface modification amount as follows.

< BET specific surface area >

Colloidal silica was preliminarily dried on a hot plate, and then heat-treated at 800 ℃ for 1 hour to prepare a sample for measurement. The BET specific surface area was measured using the prepared measurement sample.

< primary particle diameter >

Will pass through 2727/specific surface area (m)²The calculated value of/g) was taken as the primary particle diameter (nm) of the colloidal silica.

< Secondary particle diameter >

As a measurement sample for the dynamic light scattering method, a measurement sample was prepared by adding colloidal silica to a 0.05 mass% aqueous solution of Sodium Dodecyl Sulfate (SDS) and homogenizing the mixture. Using this sample for measurement, the secondary particle diameter was measured by a dynamic light scattering method ("ELSZ-2000S", manufactured by Otsuka electronics Co., Ltd.).

< association ratio >

The value calculated from the secondary particle size/primary particle size was used as the association ratio.

< true specific gravity >

The true specific gravity was measured by a measurement method in which the sample was dried and solidified on a hot plate at 150 ℃ and then held in a furnace at 300 ℃ for 1 hour, and then measured by a liquid phase displacement method using ethanol.

< amount of surface modification >

The colloidal silica solution was centrifuged at 77,000G at 5 ℃ for 90 minutes. The obtained precipitate was dried at 60 ℃ for 12 hours, then, silica was pulverized and dried at 60 ℃ under reduced pressure for 2 hours to prepare a sample for measurement. Using this sample for measurement, the amount of carboxyl groups on the surface was measured by X-ray photoelectron spectroscopy under the following conditions.

Measurement machine: K-Alpa + irradiation X-ray and Single Crystal spectroscopic Al Ka manufactured by Thermo Fisher Scientific Co., Ltd

X-ray spot diameter: 400 μm

Wherein the ratio of states of bond energies 289.4 to 289.8eV is calculated as the amount of carboxyl groups on the particle surface using a value normalized with the bond energy of C-C, C-H being 284.6 eV. The state ratio is calculated using a Relative Sensitivity Factor (RSF) attached to the apparatus.

The results of evaluating the physical properties of the colloidal silicas of the examples and comparative examples are shown in table 1.

[ Table 1]

For the colloidal silicas of examples and comparative examples, the Zeta potential was evaluated as follows.

< Zeta potential >

The Zeta potential of the colloidal silica was measured using a measuring apparatus using an ultrasonic attenuation method.

The results of Zeta potential measurement of colloidal silicas of examples and comparative examples are shown in fig. 1.

< grinding test 1 > grinding test of Co

The colloidal silicas of examples and comparative examples were adjusted to a silica particle concentration of 8 wt%, and a grinding test was conducted under the following conditions.

Grinding machine: NF-300 CMP manufactured by NANO FACTOR, Inc

Polishing the pad: NITTA HAAS IC1000^TMPad

Slurry supply rate: 100mL/min

The rotation speed of the grinding head is as follows: 46rpm

Platform rotation speed: 120rpm

Grinding pressure: co film … 2psi, TEOS film … 3psi

Grinding time: co film … 0.5min, TEOS film … 2min

Film thickness measuring machine: co film … resistance type film thickness measuring machine, TEOS film … optical interference type film thickness measuring machine

The results of polishing test 1 are shown in table 2.

[ Table 2]

According to the results of the polishing test 1, when the colloidal silica S1 obtained in example 1 was used (example 3), the polishing rate for cobalt (Co) was set toOn the other hand, when the non-modified colloidal silica S3 and the sulfonic acid-modified colloidal silica S4 were used (comparative examples 4 and 5), the polishing rate was lower than that in the case of

The selectivity calculated from the polishing rate ratio of cobalt (Co) to silicon oxide film (TEOS) was 9.0 or more in the case of S1 in the example, while it was lower than 8.0 in the cases of S3 and S4 in the comparative example.

< grinding test 2 > grinding test of Co

The colloidal silicas of examples and comparative examples were adjusted to a silica particle concentration of 5 wt%, and a grinding test was conducted under the following conditions.

Grinding machine: NF-300 CMP manufactured by NANO FACTOR, Inc

Polishing the pad: NITTAHAAS IC1000^TMPad

Slurry supply rate: 50mL/min

The rotation speed of the grinding head is as follows: 90rpm

Platform rotation speed: 90rpm

Grinding pressure: co film … 4psi, TEOS film … 4psi

Grinding time: co film … 0.5min, TEOS film … 1min

Film thickness measuring machine: co film … resistance type film thickness measuring machine, TEOS film … optical interference type film thickness measuring machine

The results of polishing test 2 are shown in table 3.

[ Table 3]

According to the results of polishing test 2, when colloidal silica S1 was used, the polishing rate for cobalt (Co) was set toOn the other hand, when S5 prepared by adding maleic acid having a carboxyl group to non-modified colloidal silica is used, the polishing rate is lower than that in the case of

The selectivity calculated from the polishing rate ratio of cobalt (Co) to silicon oxide film (TEOS) was 8.0 or more when S1 was used, while it was lower than 3.0 when S3 and S4 of the comparative example were used.

< grinding test 3 > grinding test of Ru

After the colloidal silicas of example 1 and comparative example 3 were adjusted to a silica particle concentration of 2 wt%, the oxidizer concentration, pH and conductivity were adjusted as follows for the milling test.

Concentration of the oxidizing agent: sodium periodate concentration 0.25 wt% (relative to the weight of the milled slurry)

And (3) pH adjustment: 1mol/L sodium hydroxide and 10 wt% nitric acid are used

Conductivity of polishing slurry: sodium chloride was added to reach 25mS/cm

Grinding test conditions

Grinding machine: NF-300 CMP manufactured by NANO FACTOR, Inc

Polishing the pad: NITTA HAAS IC1000^TMPad

Slurry supply rate: 50mL/min

The rotation speed of the grinding head is as follows: 32rpm

Platform rotation speed: 32rpm

Grinding pressure: ru film … 6psi

Grinding time: ru film … 1min

Film thickness measuring machine: resistance type film thickness measuring machine for Ru film …

The results of polishing test 3 are shown in table 4.

[ Table 4]

According to the results of polishing test 3, when colloidal silica S1 was used, the polishing rate was equal to that of ruthenium (Ru)As described above, the polishing rate was 1.2 times or more as high as that of S5 in which maleic acid having a carboxyl group was added to non-modified colloidal silica.

Further, from the results of < polishing test 2 >, it is estimated that the selectivity of ruthenium (Ru) to silicon oxide film (TEOS) is 1.8 or more.

< grinding test 4 > grinding test of Cu

After the colloidal silica of example 1 and comparative example 3 was adjusted to a silica particle concentration of 3 wt%, the oxidizer concentration and pH were adjusted as follows for the grinding test.

Concentration of the oxidizing agent: hydrogen peroxide concentration 0.25 wt% (relative to the weight of the abrasive slurry)

And (3) pH adjustment: using 60% perchloric acid

Grinding test conditions

Grinding machine: NF-300 CMP manufactured by NANO FACTOR, Inc

Polishing the pad: NITTA HAAS IC1000^TMPad

Slurry supply rate: 50mL/min

The rotation speed of the grinding head is as follows: 32rpm

Platform rotation speed: 32rpm

Grinding pressure: cu film … 1.5psi

Grinding time: cu film … 1min

Film thickness measuring machine: resistance type film thickness measuring machine for Cu film …

The results of polishing test 4 are shown in table 5.

[ Table 5]

According to the results of polishing test 4, when colloidal silica S1 was used, the polishing rate was at the same level as that of copper (Cu)As described above, the polishing rate was 13 times or more as compared with the case of using S5 in which maleic acid having a carboxyl group was added to non-modified colloidal silica.

From the results of the polishing test 2, the selectivity of copper (Cu) to silicon oxide film (TEOS) was estimated to be 9.5 or more.