CN117425621A - Non-spherical primary silica nanoparticles and uses thereof - Google Patents

Abstract

The method for synthesizing the non-spherical primary silica nanoparticles comprises reacting under alkaline conditions an anti-reaction comprising a water-miscible organic solvent and an alkaline catalystAt least two organoalkoxysilanes should be reacted with water in the mixture. The at least two organoalkoxysilanes have different reaction rates with water under alkaline conditions. Each organoalkoxysilane has a structure of SiR ¹ R ² R ³ R ⁴ (I) Represented structure, wherein R ¹ 、R ² 、R ³ And R is ⁴ Each independently selected from OR OR R, wherein R is a substituted OR unsubstituted straight OR branched C ₁ ‑C ₁₂ Alkyl, C ₃ ‑C ₈ Alicyclic group, C ₂ ‑C ₆ Alkenyl, halogen or aryl, R ¹ 、R ² 、R ³ And R is ⁴ At least two, preferably at least three, of (a) are OR; and at least one of the at least two organoalkoxysilanes has at least three OR. Water (H) ₂ Molar ratio of O) to hydrolyzable groups (OR) on at least two organoalkoxysilanes>0 and 0<3.0 or 2.0.

Description

Non-spherical primary silica nanoparticles and uses thereof

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional patent application No.63/264,912 filed on 3 of 12 months of 2021 and U.S. provisional patent application No.63/177,539 filed on 21 of 4 months of 2021; which is incorporated by reference as if fully set forth herein.

Background

The present disclosure relates to the preparation of non-spherical primary silica nanoparticles for use as abrasives in CMP compositions.

Chemical mechanical polishing (abbreviated CMP) is a well known technique in the semiconductor industry that is used to fabricate advanced photonic, microelectromechanical and microelectronic materials and devices, such as semiconductor wafers.

CMP is used to planarize metal and/or oxide surfaces during the fabrication of materials and devices used in the semiconductor industry. CMP utilizes the interaction of chemical and mechanical interactions to achieve planarity of a surface to be polished. The chemical action is provided by a chemical composition (also referred to as a CMP composition or CMP slurry). The mechanical action is typically performed by a polishing pad, which is typically pressed against the surface to be polished and mounted on a moving platen. The movement of the platen is typically linear, rotational or orbital.

In a typical CMP process step, a wafer holder is rotated to bring a wafer to be polished into contact with a polishing pad. The CMP composition is typically applied between the wafer to be polished and the polishing pad.

The shape of the CMP abrasive has a substantial impact on its performance in the planarization process. Recently, it was found that non-spherical shaped particles can exhibit higher removal rates and higher efficiencies than round particles, and research has focused on providing methods to produce non-spherical particles in a reproducible manner.

However, reproducible synthesis of non-spherical particles is much more complex than reproducible synthesis of spherical particles known in the art. While size control is generally the only feature monitored and tailored during synthesis of spherical particles, the creation of elongated and branched particles makes it necessary to control the size of the branches in addition to the overall three-dimensional structure. Thus, it is not surprising that the industry is looking for an economical way to control the shape and branching of elongated nanoparticle structures.

Typically, these particles are nowadays prepared by a controlled aggregation process, wherein the formation of colloidal particles is deliberately driven into an unstable region in at least one stage of production, such that the intermediately formed spherical nanoparticles start to aggregate. The particles are then returned to the stable region upon formation of the desired size and structure. Examples of methods are found in U.S. Pat. No.8,529,787 to Fuso Chemical Co.Ltd.

However, such a method has significant drawbacks, not being self-regulating. Therefore, having to constantly monitor and manipulate the reaction under such highly unstable conditions is a tedious task. Furthermore, these prior art methods hardly produce variations in the various shapes and degrees of branching.

Accordingly, there is a need in the art for a method of preparing elongated and branched CMP abrasives (e.g., silica) in which nanoparticles of various shapes and sizes can be synthesized in a simple and reproducible manner.

Disclosure of Invention

The present invention meets this need by providing non-spherical primary silica nanoparticles and using the non-spherical primary silica nanoparticles as an abrasive in a CMP process.

In one aspect, a method of synthesizing non-spherical primary silica nanoparticles or a non-spherical primary silica nanoparticle dispersion is provided, wherein the method comprises:

a) Providing a first mixture comprising at least two organoalkoxysilanes, each having the structure of formula I:

wherein R is ¹ 、R ² 、R ³ And R is ⁴ Each independently selected from OR OR R, wherein R is a substituted OR unsubstituted straight OR branched C ₁ -C ₁₂ Alkyl, C ₃ -C ₈ Alicyclic group, C ₂ -C ₆ Alkenyl, halogen or aryl; and R is ¹ 、R ² 、R ³ And R is ⁴ At least two, preferably at least three, of (a) are OR;

wherein at least one of the at least two organoalkoxysilanes has R ¹ 、R ² 、R ³ And R is ⁴ At least three, preferably all, of (a) are OR; and

at least two organoalkoxysilanes have different reaction rates with water under alkaline conditions;

b) Providing a water-miscible organic solvent;

c) Providing a basic catalyst;

d) Obtaining a reaction mixture comprising a) to c); wherein the reaction mixture contains water and is according to formula: ror=m (H ₂ O)/M (OR), having a value greater than 0 and less than 3.0, OR less than 2.0; such as 0.5 to 1.5 water (H) ₂ O) molar ratio (ROR) of hydrolyzable groups (OR) on at least two organoalkoxysilanes;

e) Forming non-spherical primary silica nanoparticles by reacting at least two organoalkoxysilanes in a reaction mixture with water under alkaline conditions; and

optionally, the composition may be used in combination with,

f) Replacing at least a portion of the water-miscible organic solvent with water after formation of the non-spherical primary silica nanoparticles to obtain a non-spherical primary silica nanoparticle dispersion; and

g) If the water from a) to c) is not sufficient to meet the ROR in step d), water is added in step d).

The pH of the reaction mixture is generally in the range of 7 to 14, preferably 10 to 14, and more preferably 12 to 14.

Step d) may be performed by: (1) Adding a water-miscible organic solvent to a mixture of at least two organoalkoxysilanes to obtain a first mixture, and adding a basic catalyst to the first mixture; (2) Adding a basic catalyst to a water-miscible organic solvent to obtain a first mixture, and adding a mixture of at least two organoalkoxysilanes to the first mixture; or (3) adding a water-miscible organic solvent to a mixture of at least two organoalkoxysilanes to obtain a first mixture, adding a water-miscible organic solvent to a basic catalyst to obtain a second mixture, and mixing the first and second mixtures in a mixer of a flow reactor. If there is not enough water in the mixture of a) to c), water may be added to the reaction mixture.

The at least two organoalkoxysilanes include, but are not limited to, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctyloxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triethylmethoxysilane, fluorotriisopropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, trimethylbutoxysilane, trifluoromethyltrimethoxysilane and trifluoromethyltriethoxysilane. Preferred at least two organoalkoxysilanes include Tetramethoxysilane (TMOS) and Tetraethoxysilane (TEOS).

In one embodiment where two organoalkoxysilanes are present, the first organoalkoxysilane may be present at about 50 to about 99 mole% and the second organoalkoxysilane may be present at about 50 to about 1 mole%. In another embodiment, the first organoalkoxysilane may be present in about 75 to about 95 mole% and the second organoalkoxysilane may be present in about 5 to about 25 mole%. In another embodiment, the first organoalkoxysilane may be present in about 85 to about 90 mole% and the second organoalkoxysilane may be present in about 15 to about 10 mole%. The mole% is based on the total mole of the two organoalkoxysilanes as 100%.

The first mixture, the second mixture and the reaction mixture may be heated and maintained at a temperature of 30 ℃ to 70 ℃, 40 ℃ to 60 ℃, or 48 ℃ to 52 ℃.

The non-spherical primary silica nanoparticles are produced in a yield of at least 50%, 75% or 85% based on the total weight of the particles produced in the process.

The non-spherical primary silica nanoparticles are produced in a weight percent yield of 3.0 wt% to 8.0 wt%, 4.0 wt% to 7.0 wt%, 4.5 wt% to 6.5 wt%, 5.5 wt% to 6.5 wt%. The weight percent yield is based on the total weight of silica nanoparticles that can be produced by the total weight of the reaction mixture.

The non-spherical primary silica nanoparticles have a shape selected from the group consisting of elongated, curved, branched, and combinations thereof, and contain<0.2, 0.1, 0.02, 0.01, 0.006, 0.005 or 0.004mmol/gSiO ₂ Nitrogen level (or nitrogen content) of (a) a nitrogen source.

In another aspect, there is provided non-spherical primary silica nanoparticles or non-spherical primary silica nanoparticle dispersion wherein the non-spherical primary silica nanoparticles have a shape selected from the group consisting of elongated, curved, branched, and combinations thereof, and contain<0.2, 0.1, 0.02, 0.01, 0.006, 0.005 or 0.004mmol/g SiO ₂ Nitrogen level (or nitrogen content) of (a) a nitrogen source.

In yet another aspect, a Chemical Mechanical Planarization (CMP) composition is provided, comprising: non-spherical primary silica nanoparticles or non-spherical primary silica nanoparticle dispersion, wherein the non-spherical primary silica nanoparticles have a shape selected from the group consisting of elongated, curved, branched, and combinations thereof, and contain<0.2, 0.1, 0.02, 0.01, 0.006, 0.005 or 0.004mmol/g SiO ₂ Nitrogen level (or nitrogen content) of (a) a nitrogen source.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) micrograph of 20,000 times of non-spherical primary silica nanoparticles prepared by example 2;

FIG. 2 is a SEM micrograph of 100,000 times of non-spherical primary silica nanoparticles prepared according to example 2;

FIG. 3 is a SEM micrograph of 20,000 times of non-spherical primary silica nanoparticles prepared according to example 3;

FIG. 4 is a SEM micrograph of 100,000 times of non-spherical primary silica nanoparticles prepared according to example 3;

FIG. 5 is a SEM micrograph of 20,000 times of non-spherical primary silica nanoparticles prepared according to example 4; and

fig. 6 is a SEM micrograph of 100,000 times of non-spherical primary silica nanoparticles prepared by example 4.

Detailed Description

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Unless otherwise indicated, the terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to"). Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All procedures described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

As used herein and in the claims, the terms "comprising," "including," "comprising," and "including" are inclusive or open-ended and do not exclude additional unrecited elements, composition components, or process steps. Thus, these terms encompass the more restrictive terms "consisting essentially of … …" and "consisting of … …". Unless otherwise indicated, all values provided herein include up to and including the endpoints given, and the values of the ingredients or components of the composition are expressed as weight percent of each ingredient in the composition.

Embodiments are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

The terms "nanoparticle" and "colloid" are synonymous and denote particles having a size between 1 and 1000 nanometers.

As used herein, "about" is intended to correspond to ±5% of the stated value.

In all such compositions, where specific components of the composition are discussed with reference to weight percent ranges including a zero lower limit, it is understood that such components may or may not be present in various embodiments of the composition, and where such components are present, they may be present in concentrations as low as 0.00001 weight percent based on the total weight of the composition in which such components are used.

The term "non-spherical silica nanoparticles" refers to both non-spherical silica primary nanoparticles and non-spherical silica secondary nanoparticles.

The term "non-spherical" as used herein includes all shapes or structures that are non-spherical. It includes, but is not limited to, "elongated", "curved structures" and "branched structures", and combinations thereof.

The term "non-spherical primary silica nanoparticle" refers to a primary silica particle having a structure in which silica grows in a nonlinear, elongated, curved, branched, or a combination of shapes. More specifically, the term refers to a structure in which silica particles grow unevenly in more than one direction simultaneously, resulting in a non-spherical structure.

In contrast to non-spherical primary silica nanoparticles, spherical primary silica nanoparticles refer to structures when the silica particles grow uniformly in all directions and thereby produce a spherical structure.

The term "non-spherical primary silica nanoparticles" excludes aggregated particles, or aggregated primary particles, or aggregated spherical primary particles.

The present invention provides a method for synthesizing non-spherical primary silica nanoparticles using at least two organoalkoxysilanes simultaneously, wherein the selected organoalkoxysilanes have different reaction rates with water under alkaline conditions.

In particular, the present invention provides methods of synthesizing non-spherical primary silica nanoparticles or non-spherical primary silica nanoparticle dispersions; wherein the method comprises the steps of:

a) Providing a first mixture of at least two organoalkoxysilanes and each organoalkoxysilane independently having a structure represented by formula I:

wherein the method comprises the steps of

R ¹ 、R ² 、R ³ And R is ⁴ Each independently selected from OR OR R, wherein R is a substituted OR unsubstituted straight OR branched C ₁ -C ₁₂ Alkyl, C ₃ -C ₈ Alicyclic group, C ₂ -C ₆ Alkenyl, halogen or aryl; and R is ¹ 、R ² 、R ³ And R is ⁴ At least two, preferably at least three, of (a) are OR;

Wherein at least one of the at least two organoalkoxysilanes has R ¹ 、R ² 、R ³ And R is ⁴ At least three, preferably all, of (a) are OR; and

at least two organoalkoxysilanes have different reaction rates with water under alkaline conditions;

b) Providing a water-miscible organic solvent;

c) Providing a basic catalyst;

d) Obtaining a reaction mixture comprising a) to c); wherein the reaction mixture contains water and is according to formula: ror=m (H ₂ O)/M (OR) having a value greater than 0 and less than 3.0, OR less than 2.0The method comprises the steps of carrying out a first treatment on the surface of the Such as 0.5 to 1.5 of water (H ₂ O) molar ratio (ROR) of hydrolyzable groups (OR) on at least two organoalkoxysilanes;

e) Forming non-spherical primary silica nanoparticles by reacting at least two organoalkoxysilanes in a reaction mixture with water under alkaline conditions; and

optionally, the composition may be used in combination with,

f) Replacing at least a portion of the water-miscible organic solvent with water after formation of the non-spherical primary silica nanoparticles to obtain a non-spherical primary silica nanoparticle dispersion; and

g) If the water from a) to c) is not sufficient to meet the ROR in step d), water is added in step d).

The pH of the reaction mixture is generally in the range of 7 to 14, preferably 10 to 14, and more preferably 12 to 14.

Step d) may be performed by: (1) Adding a water-miscible organic solvent to a mixture of at least two organoalkoxysilanes to obtain a first mixture, and adding a basic catalyst to the first mixture; (2) Adding a basic catalyst to a water-miscible organic solvent to obtain a first mixture, and adding a mixture of at least two organoalkoxysilanes to the first mixture; or (3) adding a water-miscible organic solvent to a mixture of at least two organoalkoxysilanes to obtain a first mixture, adding a water-miscible organic solvent to a basic catalyst to obtain a second mixture, and mixing the first and second mixtures in a mixer of a flow reactor. If there is not enough water in the mixture of a) to c), water may be added to the reaction mixture.

The at least two organoalkoxysilanes include, but are not limited to, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctyloxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triethylmethoxysilane, fluorotriisopropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, trimethylbutoxysilane, trifluoromethyltrimethoxysilane and trifluoromethyltriethoxysilane. Preferred at least two organoalkoxysilanes include tetramethoxysilane and tetraethoxysilane.

Preferred at least two organoalkoxysilanes include tetramethoxysilane and tetraethoxysilane.

The concentration (mole%) of the at least two organoalkoxysilanes can be any value.

In one embodiment where two organoalkoxysilanes are present, the first organoalkoxysilane may be present at about 50 to about 99 mole% and the second organoalkoxysilane may be present at about 50 to about 1 mole%. In another embodiment, the first organoalkoxysilane may be present in about 75 to about 95 mole% and the second organoalkoxysilane may be present in about 5 to about 25 mole%. In another embodiment, the first organoalkoxysilane may be present in about 85 to about 90 mole% and the second organoalkoxysilane may be present in about 15 to about 10 mole%. The mole% is based on the total mole of the two organoalkoxysilanes as 100%.

The first mixture, the second mixture and the reaction mixture may be heated and maintained at a temperature of 30 ℃ to 70 ℃, 40 ℃ to 60 ℃, or 48 ℃ to 52 ℃.

The non-spherical primary silica nanoparticles are produced in a yield of at least 50%, 75% or 85% based on the total weight of particles produced in the process. That is, 50%, 75% or 85% of the total particles produced in the process are non-spherical primary silica nanoparticles.

The non-spherical primary silica nanoparticles are produced in a weight percent yield of 3.0 wt% to 8.0 wt%, 4.0 wt% to 7.0 wt%, 4.5 wt% to 6.5 wt%, 5.5 wt% to 6.5 wt%. The weight percent yield is based on the total weight of silica nanoparticles that can be produced by the total weight of the reaction mixture.

The non-spherical primary silica nanoparticles have a shape selected from the group consisting of elongated, curved, branched, and combinations thereof, and contain<0.2, 0.1, 0.02, 0.01, 0.006, 0.005 or 0.004mmol/g SiO ₂ Nitrogen level (or nitrogen content) of (a) a nitrogen source.

Likewise, the term "non-spherical primary nanoparticle" does not include aggregated particles, such as aggregated primary particles.

The methods disclosed herein allow the degree of elongation, bending, and/or branching to be adjusted to a desired degree.

The components of the reaction mixture and the reaction process will be described in detail herein.

Organoalkoxysilane

The process is a well known prior art method for preparing spherical silica particles. At->In the process, tetraethylorthosilicate (TEOS) is added to a solution of excess water, alcohol and ammonium hydroxide with stirring to form spherical nanoparticles. However, the method of the invention comprises a combination of +. >Modification of the process, which results in surprising and unexpected results for non-spherical primary silica nanoparticles.

That is, the process of the present invention comprises the step of reacting at least two organoalkoxysilanes with water in a reaction mixture.

Each of the at least two organoalkoxysilanes independently has a structure represented by formula I shown below:

wherein the method comprises the steps of

R ¹ 、R ² 、R ³ And R is ⁴ Each independently selected from OR OR R, wherein R is a substituted OR unsubstituted straight OR branched C ₁ -C ₁₂ Alkyl, C ₃ -C ₈ Alicyclic group, C ₂ -C ₆ Alkenyl, halogen or aryl, wherein R ¹ 、R ² 、R ³ And R is ⁴ At least two, preferably at least three, of which are OR.

At least one of the at least two organoalkoxysilanes has R ¹ 、R ² 、R ³ And R is ⁴ Preferably all OR.

Examples of the organoalkoxysilane represented by formula I include Tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetraisopropoxysilane, tetrabutoxysilane, tetraoctyloxysilane, methyltrimethoxysilane (MTMS), methyltriethoxysilane, methyltrisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triethylmethoxysilane, fluorotriisopropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, trimethylbutoxysilane, trifluoromethyltrimethoxysilane and trifluoromethyltriethoxysilane.

At least two organoalkoxysilanes should be deliberately chosen to have different reaction rates with water under alkaline conditions. Thus, siO of each organoalkoxysilane ₂ Seed formation begins at different times.

Without intending to be bound by any particular theory, the present invention is exemplified by the use of two organoalkoxysilanes in the reaction, an organic compound having a faster reaction rateThe alkoxysilane first reacts with water to form silanol, followed by SiO formation according to accepted LaMer theory ₂ Seed. At the same time as these seeds begin to grow, other organoalkoxysilanes with slower reaction rates begin to produce new silanol, which then also produces new seeds. Thus, due to the different reaction rates of the two organoalkoxysilanes with water, the seed formation and particle growth reactions occur simultaneously. The new seed may grow on its own or the new seed may be attached to the grown seed to form another seed. Due to the interference of the reactions of the two organoalkoxysilanes, the seed formation and growth are no longer separated, thus defining a heterogeneous growth of particles in all dimensions. Thus, the process of the present invention results in surprising and unexpected non-spherical primary silica nanoparticles.

This process is unique in that at least two organoalkoxysilanes having different reaction rates with water under alkaline conditions are used simultaneously, as compared to known processes in which only one organosiloxane silane is used or one organosiloxane silane is used at a time.

In one embodiment where two organoalkoxysilanes are present, the first organoalkoxysilane may be present at about 50 to about 99 mole% and the second organoalkoxysilane may be present at about 50 to about 1 mole%. In another embodiment, the first organoalkoxysilane may be present in about 75 to about 95 mole% and the second organoalkoxysilane may be present in about 5 to about 25 mole%. In another embodiment, the first organoalkoxysilane may be present in about 85 to about 90 mole% and the second organoalkoxysilane may be present in about 15 to about 10 mole%. The mole% is based on the total mole of the two organoalkoxysilanes as 100%.

In some embodiments, the at least two organoalkoxysilanes are TEOS and TMOS. In embodiments, TEOS is present from about 75 to about 98 mole% and TMOS is present from about 2 to about 25 mole%, more preferably TEOS is present from about 85 mole% to about 95 mole% and TMOS is present from about 5 mole% to about 15 mole%, and most preferably TEOS is present from about 88 mole% to about 92.5 mole% and TMOS is present from about 7.5 to about 12 mole%. For example, in one embodiment, TEOS is present at 90 mole% and TMOS is present at 10 mole%.

Water and its preparation method

Water is the reactant in the process of the present invention. In relation to the artThe inventors have found that, in addition to the different reaction rates of at least two organoalkoxysilanes, the effect on the shape of the silica nanoparticles can also be influenced by the amount of water present in the reaction mixture, as opposed to what is known about the process. Although the literature generally teaches->Excess water is used in the process, but the excess water used with a mixture of at least two organoalkoxysilanes results in only a small deviation from spherical. The inventors have found that if less water is used for the hydrolysis reaction in the current process, a more pronounced deviation is observed. Preferably, the water content is present in a molar ratio ROR of less than 3 or less than 2, where ROR is defined as the molar ratio of water to hydrolyzable groups of the organoalkoxysilane, as ror=m (H ₂ O)/M (OR). Most preferably, the ROR is between 0.5 (the stoichiometric minimum of complete hydrolysis and condensation) and 1.0.

It is preferred to use water as the sole water source for the catalyst solution (e.g., 25-35% aqueous ammonia solution).

If the catalyst solution used in the process does not contain or does not have sufficient water, water may be added to the reaction mixture.

Water-miscible organic solvents

A water miscible organic solvent is used in the process of the present invention.

Examples of the organic solvent include alcohols, ketones, ethers, glycols and esters, preferably alcohols. More particularly, alcohols such as methanol, ethanol, propanol and butanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycol ethers such as propylene glycol monopropyl ether; diols such as ethylene glycol, propylene glycol and hexylene glycol; and esters such as methyl acetate, ethyl acetate, methyl lactate and ethyl lactate are preferred. Among them, methanol or ethanol is more preferable, and ethanol is particularly preferable. These water-miscible organic solvents may be used alone or as a mixture of two or more.

The water-miscible organic solvent is preferably used in the reaction mixture in an amount of about 25 to about 95 weight percent of the total weight of the reaction mixture. In other embodiments, the water-miscible organic solvent is used in an amount of 40% to about 90% by weight of the reaction mixture, or in an amount of about 50% to about 80% by weight.

Basic catalyst

At least one basic catalyst is used in the process of the invention.

The basic catalyst is selected from ammonia (NH) ₃ ) Ammonium hydroxide, organic amines, alkanolamines, quaternary ammonium hydroxides, and combinations thereof.

Preferred basic catalysts include ammonia (NH) ₃ ) Or at least one organic amine.

Examples of suitable organic amines for use as the at least one basic catalyst include hexylamine, 5-amino-2-methylpentane, heptylamine, octylamine, nonylamine, decylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, di-N-butylamine, di-tert-butylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, pentylmethylamine, methylisopentylamine, tripropylamine, tributylamine, tripentylamine, dimethylethylamine, methyldiethylamine, methyldipropylamine, N-ethylenemethylamine, N-ethyleneethylamine, N-ethylenepropylamine, N-butylethyleneamine (butyl amine ethylidene), alkanolamines, ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, 1-amino-2-propanol, N-methylamine isopropanol, N-ethyl-isopropanolamine, N-propylisopropanolamine, 2-aminopropane-1-ol, N-methyl-2-aminopropane-1-ol, N-ethyl-2-aminopropane-1-ol, N-ethyl-1-aminopropane-3-amino-1-ol, N-methyl-3-amino-2-aminopropane-1-ol, N-amino-3-amino-2-ethyl-1-amino-2-amino-butane, N-amino-1-amino-2-amino-butane, 2-aminobutan-1-ol, N-methyl-2-aminobutan-1-ol, N-ethyl-2-aminobutan-1-ol, N-hydroxy-methylethanolamine, N-hydroxymethyl ethylenediamine, N' -bis (hydroxymethyl) ethylenediamine, N-hydroxymethyl propanolamine, ethylenediamine, propylenediamine, triethylenediamine, tetramethylenediamine, 1, 3-diaminobutane, 2, 3-diaminobutane, pentamethylenediamine, 2, 4-diaminopentane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, N-methylethylenediamine, N-dimethylethylenediamine, trimethylethylenediamine, N-ethylethylenediamine, N-diethylethylenediamine, triethylethylenediamine, 1,2, 3-triaminopropane, hydrazine, tris (2-aminoethyl) amine, tetrakis (aminomethyl) methane, diethylenetriamine, triethylenetetramine, tetraethylpentamine, heptaethyleneoctamine, nonaethyleneamine, diazabicyclo undecylenamine, N-ethyleneimine, polyethyleneimine, and mixtures thereof.

Examples of suitable alkanolamines include primary, secondary and tertiary alkanolamines having from 1 to 5 carbon atoms, such as N-methylethanolamine (NMEA), monoethanolamine (MEA), N-methyldiethanolamine, diethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine, 2- (2-aminoethylamino) ethanol, 2- (2-aminoethoxy) ethanol, triethanolamine and mixtures thereof. In one embodiment, the alkanolamine is selected from the group consisting of Triethanolamine (TEA), diethanolamine, N-methyldiethanolamine, diisopropanolamine, N-methylethanolamine, and mixtures thereof.

Examples of suitable quaternary ammonium hydroxides for use as the at least one basic catalyst include tetramethyl ammonium hydroxide (TMAH), tetraethyl ammonium hydroxide, tetrabutyl ammonium hydroxide (TBAH), tetrapropyl ammonium hydroxide, trimethyl ethyl ammonium hydroxide, (2-hydroxyethyl) trimethyl ammonium hydroxide, (2-hydroxyethyl) triethyl ammonium hydroxide, (2-hydroxyethyl) tripropyl ammonium hydroxide, (1-hydroxypropyl) trimethyl ammonium hydroxide, ethyltrimethyl ammonium hydroxide, diethyl dimethyl ammonium hydroxide, and benzyl trimethyl ammonium hydroxide, or mixtures thereof.

The amount of the basic catalyst added to the reaction mixture may be appropriately adjusted so that the pH of the reaction mixture is maintained in the range of 7 to 14, preferably 10 to 14, more preferably 12 to 14.

The basic catalyst may be added to a mixture of at least two organoalkoxysilane and a water miscible organic solvent; or may be added first to a water-miscible organic solvent and then to a mixture of at least two organoalkoxysilanes to obtain a reaction mixture.

In a preferred embodiment, the basic catalyst is added to a mixture of at least two organoalkoxysilane and a water miscible organic solvent with stirring to obtain a reaction mixture. The catalyst may be present as an aqueous solution, such as a 25% -35% aqueous ammonia solution, so that the water as a reactant is added simultaneously with the catalyst.

The catalyst addition may be slow or all at once. Preferably, the catalyst is added rapidly to the preheated silane/solvent mixture with vigorous stirring.

Typical reaction times are 1 to 5 hours. Preferably, the silane/solvent mixture and the catalyst are heated. Still more preferably, both are heated to the same temperature prior to mixing. Exemplary temperatures include those in the range of 30 ℃ to 70 ℃, 40 ℃ to 60 ℃, and 48 ℃ to 52 ℃.

The process should be such as to avoid volatile catalysts (e.g., NH ₃ ) Designed in such a way as to evaporate from the reaction mixture. A continuous tube/flow reactor or batch reactor with sufficiently long tubing may be used to ensure that the reaction proceeds to the desired extent (particle formation).

When the reaction is performed in the presence of a nitrogen-containing basic catalyst, nitrogen compounds may be trapped inside the colloidal silica abrasive particles during the particle growth, thereby obtaining colloidal silica abrasive particles containing nitrogen compounds internally incorporated inside the colloidal silica abrasive particles. The nitrogen level or nitrogen content (millimoles per gram of silica or mmol per gram of silica) may be used to measure the nitrogen contained in the particles.

Because the method of the invention is relative to the typicalThe process is carried out with less water and in some embodiments, excess water may be added after the reaction is complete or nearly complete, with stirring for 1 to 60 minutes to ensure that all reaction sites on the organoalkoxysilane are exhausted. Preferably, excess water is added to achieve a ROR value of at least 1.0, most preferably 2.0. Due to the unique manner of particle growth, colloidal silica having a non-spherical, elongated, curved and branched structure produced by the method of the present invention can be obtained.

Optionally, depending on the desired characteristics of the colloidal silica particles, a second growth step may be performed. For example, in one embodiment, the process of the present invention further comprises the step of adding at least an organoalkoxysilane and water, and optionally further basic catalyst, to the reaction mixture. Although more than one organoalkoxysilane may be added, it is preferred that the optional second growth step is performed with only one organoalkoxysilane compound (e.g., such as TEOS). The rate of addition in the second step is preferably a drop wise addition of organoalkoxysilane to maintain the pH of the liquid mixture at > 7, preferably 12 to 14. The organoalkoxysilane for the optional second growth step is preferably added at a rate of 0.7 to 41g silica/hr/kg reaction mixture.

The next step of the process of the present invention comprises, once the non-spherical primary silica nanoparticles are formed, exchanging at least a portion of the water-soluble organic solvent for water to obtain a dispersion of silica nanoparticles in water. Such a solvent exchange step may use any known method of exchanging an organic solvent for water, such as distillation or cross-flow filtration. The solvent exchange step is preferably carried out until as much organic solvent as possible is removed, subject to any inherent limitations of the process used. Preferably, the exchanging step comprises adding water in an amount to achieve a molar ratio of water to hydrolyzable groups (ROR) on the organoalkoxysilane greater than or equal to 2.0. When the solvent exchange is carried out by distillation, it is preferable to add a dilute aqueous ammonia solution (1-15% NH in water) during at least part of the process ₃ ) Rather than pure water, to ensure that the pH is never below 8, a pH below 8 is possibleAffecting the colloidal stability.

In a preferred embodiment, the dispersion obtained after the solvent exchange step is concentrated by any suitable means to obtain a solids concentration of 15-25% or higher.

The process of the present invention may include other optional steps such as chemical modification of the surface of the colloidal silica produced. There are important silicon dioxide surface features that will affect the etch rate and final surface conditions. Typical silica surfaces are capped (covered) with-OH groups under neutral or basic conditions. The silica surface is hydrophilic and thus "wettable". These groups activate the surface to a variety of possible chemical or physiological absorption phenomena. The Si-OH groups impart a weak acidic effect that allows the formation of salts and exchange protons (h+) (similar to ion exchange resins) for various metals. These Si-O ^- And Si-OH may also act as a ligand for complexation of Al, fe, cu, sn and Ca. Of course, the surface is highly dipolar and thus static charge can accumulate or dissipate, depending on the pH, ion concentration and charge of the bulk solution. This accumulated surface charge can be measured as zeta potential.

CMP liquids containing abrasive particles may require pH adjustment, for example, where a high zeta potential may be achieved to maintain colloidal stability. In liquids containing abrasives, settling of particles from suspension is undesirable. The charge around the interface between the particles and the liquid strongly influences the stability of the colloidal system. Zeta potential measures the potential of the particle surface at its shear plane and provides a general measure of colloidal system stability. In order to maintain a stable colloidal system, a high zeta potential of positive or negative charge is required. The zeta potential of a particular particle decreases to zero at a pH corresponding to its isoelectric point. Therefore, to enhance the stability of the colloid, the pH of the system should be different from the pH at the isoelectric point. For example, the isoelectric point of the silica slurry is at pH 2; the silica slurry is then preferably maintained at an alkaline pH to enhance colloidal stability. Other variables that affect the colloidal stability of the particle system include particle density, particle size, particle concentration, and chemical environment.

Thus, the optional step of chemically modifying the surface of the resulting colloidal silica may include any surface modification to adjust the zeta potential of the colloidal dispersion or to impart any other desired functionality to the surface of the colloidal silica. The colloidal silica particles may be surface modified using any suitable method known in the art. This includes modifying the surface of the colloidal silica by adding metal ions, boron, aluminum, etc. The optional modification step also includes treatment with a surface modifier (e.g., silane) including amino-containing silanes, sulfur-containing silanes, carboxyl-containing silanes, phosphorus-containing silanes, alkylsilanes, and the like.

In one embodiment, the step of modifying the surface of the non-spherical silica nanoparticle comprises replacing at least a portion of the surface silanol groups with at least one member selected from the group consisting of organosilanes, organic polymers, inorganic polymers, surfactants, and inorganic salts.

In a preferred embodiment, the step of modifying the surface of the non-spherical silica nanoparticle comprises replacing at least a portion of the surface silanol groups with an organosilane selected from the group consisting of amino-functional alkoxysilanes, cyano-functional alkoxysilanes, alkyl-functional and aryl-functional alkoxysilanes, thio-silanes and phosphosilanes. Examples of the sulfur silane include mercaptopropyl triethoxysilane, mercaptopropyl trimethoxysilane, and bis [3- (triethoxysilyl) propyl ] polysulfide (registered trademark "Si 69" of Evonik). Examples of the phosphorus silane include N-diphenylphosphoryl-3-aminopropyl triethoxysilane, 3- (trihydroxysilyl) propyl methylphosphonic acid (ammonium salt), and 2- (diethylphosphatoethyl) methyldiethoxysilane.

In some applications, it may be preferable that the pH of the dispersion is acidic. This can be achieved by any means known to the person skilled in the art, such as, for example, by passing the colloidal silica dispersion through an ion exchange resin until the cations present are H ⁺ Ion exchange, or by addition of a suitable acid. This ion exchange may be performed before or after the optional surface modification step.

Various particle stabilizing additives may be added to the dispersion. These include surfactant compounds. Suitable surfactant compounds include, for example, any of a variety of nonionic, anionic, cationic or amphoteric surfactants known to those skilled in the art. The surfactant compound may be present in the slurry composition at a concentration of from about 0 wt% to about 1 wt% of the total weight of the slurry, and when present, is preferably present at a concentration of from about 0.001 wt% to about 0.1 wt%.

Other compounds may be added to the dispersions prepared herein, depending on the particular end use. These include chelating agents, corrosion inhibitors, colloidal stabilizers, organic or inorganic salts and biological agents such as bactericides, biocides and fungicides.

Silica nanoparticles produced

The silica nanoparticles produced herein comprise predominantly non-spherical primary silica particles, i.e. particles in which they are elongated and/or curved and/or branched. Preferably, the non-spherical primary silica nanoparticles comprise about 75%, 85% or more of the silica nanoparticles produced according to the inventive methods disclosed herein.

From a commercial point of view, an important point of the production process of non-spherical primary nanoparticles is the yield. Yield is defined as the total weight of silica nanoparticles that can be produced by the total weight of the reaction mixture, and is generally reported as weight percent yield.

Typically, theThe yield of the process is very limited, as attempts to obtain higher yields always lead to uncontrolled aggregation, precipitation or non-uniform size distribution. Thus (S)>The process is typically carried out in yields of 1-3%, which means that most of the reaction mixture is solvent, which needs to be removed in expensive downstream processes.

The described method of producing non-spherical primary silica nanoparticles shows a unique profileBecause it can be carried out in much higher yields than are known from the prior art The process is not possible.

The described process can be carried out in yields of 0.5-15%, preferably 3% -8%, and most preferably 5% -7%, which is a great advantage, meaning that it is known from the prior artIn contrast to the process, only about half the amount of solvent is needed. Thus, only half of the solvent must be exchanged or removed with water in the downstream process.

Working examples of the present application show yields of 4.5-6.5%, or 5.5-6.5%.

The non-spherical primary silica particles may contact each other and form certain kinds of bonds, such as hydrogen bonds or covalent bonds, and aggregate to form secondary particles. The silica secondary particles are mostly non-spherical or have an elongated, curved structure and/or a branched structure.

The term "aspect ratio" refers to the ratio of the major axis to the minor axis of a particle. Preferably, the average value of the particle aspect ratio (average aspect ratio) observed in the top view of the non-spherical primary silica nanoparticles produced according to the methods disclosed herein is preferably 1.5 or greater, and more preferably less than 5. If the average aspect ratio exceeds 5, its handling will be difficult due to an increase in viscosity or the like, and gelation may occur.

The non-spherical primary silica nanoparticles may have an average particle size of about 15nm to 200nm, about 20nm to about 150nm, about 20nm to about 120nm, about 20nm to about 110nm, about 30nm to about 100nm, about 30nm to about 90nm, about 30nm to about 80nm, or about 40nm to 70 nm. Alternatively or additionally, the non-spherical primary silica nanoparticles may have an average particle size of about ∈10nm, about ∈15nm, about ∈200nm, about ∈150nm, about ∈120nm, about ∈100deg.about ∈90nm, about ∈80nm, or about ∈70nm. Thus, the non-spherical primary silica nanoparticles may have an average particle size defined by any two of the above endpoints.

The non-spherical silica secondary nanoparticles may have any suitable average particle size. For example, the non-spherical silica secondary nanoparticles may have an average particle size of about 15nm to 600nm, about 20nm to 600nm, about 25nm to 550nm, about 30nm to 500nm, about 35nm to 450nm, about 40nm to 400nm, about 45nm to 350nm, about 50nm to 300nm, or about 50nm to 200nm. Alternatively or additionally, the average particle size of the non-spherical silica secondary nanoparticles may be about ≡15nm and ≡600nm, about ≡500nm, about +.400 nm, about +.300 nm, or about +.200 nm. Thus, the silica nanoparticles may have an average particle size defined by any two of the above endpoints. Preferably, the non-spherical primary particles of the present invention do not agglomerate or agglomerate to only a small extent to form secondary particles.

Thus, in another embodiment, the present invention provides non-spherical primary silica nanoparticles prepared by the above-described method.

Furthermore, the non-spherical primary silica nanoparticles of the present invention have a curved and/or branched structure and thus have a large aspect ratio. Since the elongated/curved/aggregated primary silica particles of the present invention are superimposed or entangled with each other, they exhibit excellent coating properties, and thus can improve coating properties when used as a carrier for an aqueous coating composition.

The non-spherical primary silica nanoparticles produced herein are excellent abrasives for CMP compositions because they exhibit high removal rates and high efficiency compared to spherical particles. Accordingly, in another embodiment, provided herein is a CMP composition comprising non-spherical primary silica nanoparticles produced according to the methods disclosed herein.

Due to the unprecedented complex structure of the particles of the present invention, when non-spherical primary silica nanoparticles are used as polishing materials, the contact resistance between the polishing material and the surface to be polished can be adjusted, thereby improving the polishing rate.

Hereinafter, the present invention is described in more detail with reference to examples and comparative examples. However, the present invention is not limited thereto.

Examples

Example 1: synthesis of elongated particles (5% TMOS 95% TEOS, ROR 0.75) 1204.96mmol ethanol was heated to 50℃with stirring. Ammonium hydroxide solution (32 wt%, 74.78 mmol) was added to give a first mixture. The mixture was further stirred until it again reached 50 ℃. Then, a mixture of Tetraethoxysilane (TEOS) (47.5 mmol) and Tetramethoxysilane (TMOS) (2.5 mmol) preheated to 50℃was added rapidly to the first mixture at once with vigorous stirring to give a reaction mixture with ROR of 0.75. Stirring was continued for 10 seconds and then stopped. The reaction mixture was kept at 50 ℃ overnight.

The dispersion was stirred, 50mmol of deionized water was slowly added, and then stirred at 50 ℃ for 8h. The particles had an average particle size of 91.2nm and a polydispersity index (PDI) of 0.078 as measured by Dynamic Light Scattering (DLS).

Example 2: synthesis of elongated particles (10% TMOS,90% TEOS, ROR 0.75)

12346.97mmol of ethanol are heated to 50℃with stirring. Ammonium hydroxide solution (32 wt%, 747.36 mmol) was added to obtain a first mixture. The mixture was further stirred until it again reached 50 ℃. Then, a mixture of Tetraethoxysilane (TEOS) (451.17 mmol) and Tetramethoxysilane (TMOS) (50.07 mmol) preheated to 50 ℃ was rapidly added to the first mixture at once with vigorous stirring to obtain a reaction mixture. Stirring was continued for 10 seconds and then stopped. The reaction mixture was kept at 50 ℃ overnight. The average particle size of the particles was 66.5nm and the pdi was 0.086 as measured by DLS.

Fig. 1 and 2 are SEM micrographs showing non-spherical primary silica nanoparticles prepared from example 2.

Example 3: (TEOS: TPOS 80:20, ROR 0.75)

1234.7mmol of ethanol are heated to 50℃with stirring. Ammonium hydroxide solution (32 wt%, 70.11 mmol) was added to obtain a first mixture. The first mixture was further stirred until it again reached 50 ℃. Then, a mixture of Tetraethoxysilane (TEOS) (40.06 mmol) and Tetrapropoxysilane (TPOS) (10.02 mmol) preheated to 50 ℃ was rapidly added to the first mixture at a time with vigorous stirring to obtain a reaction mixture. Stirring was continued for 10 seconds and then stopped. The reaction mixture was kept at 50 ℃ overnight. The particles had an average particle size of 50.0nm and a PDI of 0.051 as measured by DLS.

Fig. 3 and 4 are SEM micrographs showing non-spherical primary silica nanoparticles prepared from example 3.

Example 4: (60% TEOS,40% TPOS, ROR 0.75)

1234.7mmol of ethanol are heated to 50℃with stirring. Ammonium hydroxide solution (32 wt%, 74.78 mmol) was added to obtain a first mixture. The mixture was further stirred until it again reached 50 ℃. Then, a mixture of Tetraethoxysilane (TEOS) (30.50 mmol) and Tetrapropoxysilane (TPOS) (20.50 mmol) preheated to 50 ℃ was rapidly added to the first mixture at once with vigorous stirring to obtain a reaction mixture. Stirring was continued for 10 seconds and then stopped. The reaction was kept at 50 ℃ overnight. The average particle size of the particles was 53.5nm as measured by DLS, and PDI was 0.053.

Fig. 5 and 6 are SEM micrographs showing non-spherical primary silica nanoparticles prepared from example 4.

Example 5: ion exchange and pH shift to acidic pH

1247.1g of nanoparticle dispersion from example 2 are stirred and 700g of ion exchanger Amberlite IRN-150 are added. Stirring was continued for 1 hour, after which the ion exchanger was filtered off. The pH was measured to be 4.3 with a pH electrode. Slowly add HNO ₃ (1%) until the pH of the dispersion was 2.0.

Example 6: surface modification, zeta potential modulation and solvent transfer

42.44mmol (3-aminopropyl) trimethoxysilane were diluted with 3.61mol of methanol. Concentrated nitric acid (65 wt%, 46.7 mmol) was added rapidly to the solution with vigorous stirring. Stirring was continued for 1 min.

The ion-exchanged and acidified particle dispersion of example 5 was vigorously stirred and the freshly prepared acidified aminosilane solution described above was added rapidly. Stirring was continued for 1h at room temperature, after which the dispersion was heated to 70℃and stirred at this temperature for a further 2 h.

The dispersion was then transferred to a rotary evaporator, the alcohol was gradually removed and replaced by adding water until the dispersion reached a solids content of 21.5% by weight in water.

Finally, the dispersion was filtered through a 2 μm glass fiber filter.

At pH 2.2, the particles had an average particle size of 90.5nm, PDI of 0.058 as measured by DLS, and zeta potential: 40.3mV.

Example 7: synthesis of elongated particles with second growth (90% TEOS,10% TMOS, ROR 0.75)

32.35mol of absolute ethanol was mixed with 1.58mol of tetraethoxysilane and 0.18mol of tetramethoxysilane to obtain a first mixture. The first mixture was stirred and heated to 66 ℃. 2.63 molar ammonia solution (32%) was added rapidly with vigorous stirring and stirring was continued for 10s before stopping. The temperature was reduced to 60 ℃.

The reaction mixture was kept at 60 ℃ for 12h, and then particle size was measured by DLS. The particles had an average particle size of 77.7nm and a PDI of 0.054.

25.53mol of deionized water was heated to 60℃and then slowly added with stirring to the reaction mixture, which still had a temperature of 60 ℃. Stirring was continued for 30 minutes at 60 ℃. Tetraethoxysilane (1.67 mol) was then added with a metering pump over the course of 3h while stirring was continued. Finally, the mixture was stirred at 60℃for 12h, after which the particle size distribution was measured using DLS. The particles had an average particle size of 89.3nm and a PDI of 0.047.

Comparative example 1 (100% TEOS-non-inventive)

A mixture of absolute ethanol (1, 201.27 mmol) and Tetraethoxysilane (TEOS) (50.00 mmol) was heated to 55deg.C with stirring. Ammonium hydroxide solution (32%, 74.78 mmol) was added rapidly with vigorous stirring. The temperature was reduced to 50 ℃. Stirring was continued for 10 seconds, then closed and the reaction mixture was kept at 50 ℃ for 12 hours, after which the particle size distribution was measured with DLS.

The average particle size of the particles was 47.4nm and the PDI was 0.025.

A very low PDI is an indication that the particles are hardly elongated or non-spherical and are therefore disadvantageous in terms of the required properties.

Example 8: nitrogen level (or nitrogen content)

The nitrogen level or nitrogen content in the non-spherical primary silica particles prepared according to the present invention as shown in the foregoing examples 1 and 2 was measured by dissolving the dried non-spherical primary silica particles in KOH and then measuring nitrogen species by ion chromatography. The dispersion medium is freed from nitrogen-containing substances by cross-flow filtration prior to drying the granules.

The results are shown in Table 1.

TABLE 1

As apparent from the results shown in Table 1, even if a concentrated aqueous ammonia solution is used as a catalyst in the reaction, the nitrogen content in the non-spherical primary silica particles is extremely low and is in the range of 0.0041 to 0.0058mmol/g SiO ₂ Within a range of (2).

This nitrogen content is about 50 times lower than the nitrogen content incorporated in the silica particles disclosed in US 9422456 and US 949972, wherein the nitrogen content is measured by the same method.

The nitrogen content in the non-spherical primary silica particles prepared in this application was lower than the nitrogen content measured from the particles used as controls in US 9422456 and US 949972 <0.02mmol/g SiO ₂ )。

The foregoing description of the examples and embodiments should be taken as illustrative rather than limiting the invention as defined by the claims. As will be readily appreciated, many variations and combinations of the above features may be utilized without departing from the present invention as set forth in the claims. Such variations are intended to be included within the scope of the appended claims.

Claims (27)

1. A method of synthesizing non-spherical primary silica nanoparticles, comprising:

a) Providing a mixture of at least two organoalkoxysilanes, wherein each organoalkoxysilane independently has a structure represented by formula I:

wherein the method comprises the steps of

R ¹ 、R ² 、R ³ And R is ⁴ Each independently selected from OR OR R, wherein R is a substituted OR unsubstituted straight OR branched C ₁ -C ₁₂ Alkyl, C ₃ -C ₈ Alicyclic group, C ₂ -C ₆ Alkenyl, halogen or aryl, wherein R ¹ 、R ² 、R ³ And R is ⁴ At least two, preferably at least three, of (a) are OR;

at least one of the at least two organoalkoxysilanes has R ¹ 、R ² 、R ³ And R is ⁴ Preferably all OR; and

the at least two organoalkoxysilanes have different reaction rates with water under alkaline conditions;

b) Providing a water-miscible organic solvent;

c) Providing a basic catalyst;

d) Obtaining a reaction mixture comprising a) to c); wherein the reaction mixture contains water and is according to formula (la): ror=m (H ₂ O)/M (OR), water (H) ₂ O) to the hydrolyzable groups (OR) on the at least two organoalkoxysilanes is greater than 0 and less than 3.0, OR less than 2.0; such as 0.5 to 1.5;

e) Forming non-spherical primary silica nanoparticles by reacting the at least two organoalkoxysilanes with water in the reaction mixture under alkaline conditions; and

optionally, the composition may be used in combination with,

f) Replacing at least a portion of the water-miscible organic solvent with water after forming the non-spherical primary silica nanoparticles to obtain a non-spherical primary silica nanoparticle dispersion; and

g) If the water from a) to c) is not sufficient to meet the ROR in step d), water is added in step d).

2. The method of claim 1, wherein the non-spherical primary silica nanoparticles have a shape selected from the group consisting of elongated, curved, branched, and combinations thereof; and contains<0.2、<0.1、<0.05、<0.02、<0.01、<0.006、<0.005 or<0.004mmol/g SiO ₂ Nitrogen level of (2).

3. The method according to claim 1, wherein step d) can be performed by: (1) Adding the water-miscible organic solvent to a mixture of the at least two organoalkoxysilanes to obtain a first mixture, and adding the basic catalyst to the first mixture; (2) Adding the basic catalyst to the water-miscible organic solvent to obtain a first mixture, and adding a mixture of the at least two organoalkoxysilanes to the first mixture; or (3) adding the water-miscible organic solvent to the mixture of the at least two organoalkoxysilanes to obtain a first mixture, adding the water-miscible organic solvent to the basic catalyst to obtain a second mixture, and mixing the first mixture and the second mixture in a mixer of a flow reactor.

4. The method of claim 1, wherein the first mixture and the reaction mixture are heated and maintained at a temperature of 30 ℃ to 70 ℃, 40 ℃ to 60 ℃, or 48 ℃ to 52 ℃.

5. The process of claim 1, wherein the process is carried out in a closed vessel, optionally at moderate pressure, or in a flow reactor.

6. The method of claim 1, wherein each of the at least two organoalkoxysilane is selected from the group consisting of tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctyloxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triethylmethoxysilane, fluorotriisopropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, trimethylbutoxysilane, trifluoromethyl trimethoxysilane, and trifluoromethyl triethoxysilane.

7. The method of claim 1 wherein two organoalkoxysilanes are used in the mixture of the at least two organoalkoxysilanes, and one of the organoalkoxysilanes is present at about 50 to about 99 mole percent and the other organoalkoxysilane is present at about 50 to about 1 mole percent.

8. The method of claim 1, wherein the at least two organoalkoxysilanes include tetramethoxysilane and tetraethoxysilane, and the tetramethoxysilane is present at about 2 to about 25 mole percent or 7.5 to 12.5 mole percent based on a total mole of the at least two organoalkoxysilanes.

9. The method of claim 1, wherein the at least two organoalkoxysilanes include tetramethoxysilane and tetraethoxysilane, and the molar ratio (ROR) of water to hydrolyzable groups (OR) on the at least two organoalkoxysilanes is 0.75.

10. The process according to claim 1, wherein the basic catalyst is selected from ammonia (NH ₃ ) Ammonium hydroxide, organic amines, alkanolamines, quaternary ammonium hydroxides, and combinations thereof.

11. The process of claim 1, wherein the pH of the reaction mixture is 7 to 14, 10 to 14, or 12 to 14.

12. The method of claim 1, wherein the basic catalyst comprises NH ₃ Or an organic amine, and the pH of the reaction mixture is greater than 8 or greater than 9.

13. The process of claim 1, wherein step (d) is performed in a continuous flow reactor or a batch reactor.

14. The method of claim 1, wherein the replacing step f) comprises adding an amount of water to achieve a water (H) of greater than or equal to 1.0 or greater than or equal to 2.0 ₂ O) to the hydrolyzable groups (OR) on the organoalkoxysilane (ROR).

15. The process of claim 1, further comprising a second growth step of adding organoalkoxysilane and water and optionally a basic catalyst to the reaction mixture immediately after step d).

16. The method of claim 1, wherein the replacing step f) comprises at least one of distillation and membrane filtration.

17. The method of claim 1, further comprising the step of changing the pH of the dispersion from alkaline to acidic by passing the non-spherical primary silica nanoparticle dispersion obtained in step f) through an ion exchanger and optionally adding an acid.

18. The method of claim 1, further comprising the step of modifying the surface of the non-spherical primary silica nanoparticles by treating the surface with a surface modifying agent selected from the group consisting of organosilanes, organic polymers, inorganic polymers, surfactants, inorganic salts, metal ions, and combinations thereof.

19. The method of claim 18, wherein the organosilane used to modify the surface is selected from the group consisting of amino-functional alkyl-alkoxysilanes, cyano-functional alkyl-alkoxysilane, alkyl-functional and aryl-functional alkoxysilane, sulfur-containing silane, carboxyl-containing silane, phosphorus-containing silane, alkylsilane, and combinations thereof.

20. The method of claim 1, wherein the non-spherical primary silica nanoparticles are produced in a weight percent yield of 3.0 wt% to 8.0 wt%, 4.0 wt% to 7.0 wt%, 4.5 wt% to 6.5 wt%, or 5.5 wt% to 6.5 wt%, based on the total weight of silica nanoparticles that may be produced by the total weight of the reaction mixture.

21. The method of claim 1, wherein the non-spherical primary silica nanoparticles are produced in a yield of at least 50%, 75%, or 85% based on the total weight of particles.

22. A non-spherical primary silica nanoparticle, wherein the non-spherical primary silica nanoparticle has a shape selected from the group consisting of elongated, curved, branched, and combinations thereof; and contains<0.2、<0.1、<0.05、<0.02、<0.01、<0.006、<0.005 or<0.004mmol/gSiO ₂ Nitrogen level of (2).

23. A non-spherical primary silica nanoparticle, wherein the non-spherical primary silica nanoparticle has a shape selected from the group consisting of elongated, curved, branched, and combinations thereof; and contains <0.2、<0.1、<0.05、<0.02、<0.01、<0.006、<0.005 or<0.004mmol/gSiO ₂ Nitrogen levels of (2); wherein the non-spherical primary silica nanoparticles are prepared by the method according to any one of claims 1 to 21.

24. A Chemical Mechanical Planarization (CMP) composition comprising:

non-spherical primary silica nanoparticles having a shape selected from the group consisting of elongated, curved, branched, and combinations thereof; and contains<0.2、<0.1、<0.05、<0.02、<0.01、<0.006、<0.005 or<0.004mmol/g SiO ₂ Nitrogen level of (2).

25. The Chemical Mechanical Planarization (CMP) composition of claim 24, further comprising at least one of: colloidal stabilizers, soluble or solid catalysts, chelating agents, corrosion inhibitors, surfactants, biocides, organic or inorganic salts, and pH adjusting agents.

26. A Chemical Mechanical Planarization (CMP) composition comprising:

non-spherical primary silica nanoparticles prepared by the method according to any one of claims 1 to 21.

27. The Chemical Mechanical Planarization (CMP) composition of claim 26, further comprising at least one of: colloidal stabilizers, soluble or solid catalysts, chelating agents, corrosion inhibitors, surfactants, biocides, organic or inorganic salts, and pH adjusting agents.