Particle-linked silica fine particle dispersion liquid, production method thereof, and abrasive grain dispersion liquid

Abstract

To provide a particle-linked silica fine particle liquid dispersion having an excellent polishing property.SOLUTION: There is provided a particle-linked silica fine particle liquid dispersion containing particle-linked silica fine particles composed of a structure in which silica primary fine particles are linked with each other, with the silica fine particles contained in the particle-linked silica fine particle liquid dispersion satisfying the following requirement [1], and the particle-linked silica fine particles of a stereoscopic branched structure included in the silica fine particles, satisfying the following requirements [2] and [3]. [1] The mean particle diameter (D1) of the silica fine particles measured by a dynamic light scattering method is in a range of not smaller than 50 nm and not larger than 600 nm. [2] The particle-linked silica fine particle of a stereoscopic branched structure has a chain-like structure comprising at least one branch (a) and has a stereoscopic structure relative to the structure. [3] The particle-linked silica fine particle of the stereoscopic branched structure contains an organic polymer component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a particle-linked silica fine particle dispersion liquid, a method for producing the same, and an abrasive grain dispersion liquid.

Background Art

[0002] Among particle-linked silica sols dispersed in a solvent, as particle-linked silica sols having a shape other than spherical, chain-like, bead-like, or prolate ones are known. Such particle-linked silica sols are used, for example, as various abrasives.

[0003] Patent Document 1 discloses an invention of a particle-linked alumina-silica composite sol in which particle-linked alumina-silica composite fine particles having a structure in which two or more alumina-silica composite primary particles having an average particle diameter measured by an image analysis method in the range of 5 to 300 nm are bonded are dispersed in a dispersion medium, and a method for producing the same. In Patent Document 1, these particle-linked alumina-silica composite fine particles are characterized in that, as alumina-silica composite primary particles, they include spherical particles having a plurality of wart-like protrusions on the surface. This invention has a specific structure different from that of ordinary particle-linked silica fine particles or non-spherical alumina-silica composite fine particles. Therefore, for example, it is useful as an abrasive and an abrasive composition, and is particularly excellent in the effect of high polishing speed. However, aluminum becomes a contaminant depending on the type of polishing substrate, which is not preferable.

[0004] Patent Document 2 discloses an invention of a particle-linked silica sol in which particle-linked silica fine particles containing a structure in which two or more silica primary particles having an average particle diameter measured by an image analysis method in the range of 5 to 300 nm are bonded are dispersed in a dispersion medium, and a method for producing the same. In Patent Document 2, this particle-linked silica fine particle is characterized in that, as the silica primary particle, it contains spherical particles having a plurality of wart-like protrusions on the surface. Since this invention has a specific structure different from ordinary particle-linked silica fine particles or non-spherical silica fine particles, for example, it is useful as an abrasive and an abrasive composition, and is particularly excellent in the effect of high polishing speed. However, since it includes a tetrapod type as a bonding mode and further includes wart-like protrusions, stress concentration on the local polishing substrate is likely to occur, and polishing scratches such as scratches are likely to occur.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a particle-linked silica fine particle dispersion liquid having excellent abrasive properties, a method for producing the same, and an abrasive grain dispersion liquid.

Means for Solving the Problems

[0007] According to one aspect of the present invention, there is provided a particulate-linked silica fine particle dispersion liquid containing particulate-linked silica fine particles having a structure in which primary silica fine particles are linked, wherein the silica fine particles contained in the particulate-linked silica fine particle dispersion liquid having a structure in which the primary silica fine particles are linked satisfy the requirements of the following [1], and the particulate-linked silica fine particles having a three-dimensional branched structure included in the silica fine particles satisfy the requirements of the following [2] and [3]. [1] The average particle diameter (D1) measured by the dynamic light scattering method of the silica fine particles is in the range of 50 nm or more and 600 nm or less. [2] The particulate-linked silica fine particles having a three-dimensional branched structure have a chain-like structure having at least one branch (a) and a three-dimensional structure with respect to this structure. [3] The particulate-linked silica fine particles having a three-dimensional branched structure contain an organic component.

[0008] According to one aspect of the present invention, there is provided an abrasive grain dispersion liquid containing the particulate-linked silica fine particle dispersion liquid according to one aspect of the present invention.

[0009] According to one aspect of the present invention, there is provided a method for producing the particulate-linked silica fine particle dispersion liquid according to one aspect of the present invention, including the following step 1. Step 1: A cationic organic polymer component is added to a silica fine particle dispersion liquid having a SiO2 concentration of 1.5 mass% or more and 30 mass% or less within the range of the following ratio (WA / WS1), and then heated to 40°C or more and 98°C or less and held for 0.5 hours or more to obtain a particulate-linked silica fine particle dispersion liquid. 0.01 ≦ WA / WS1 ≦ 0.3 (Here, WS1 is the mass of silica in the silica fine particle dispersion liquid, and WA is the mass of the cationic organic polymer component.) [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a particulate-linked silica fine particle dispersion liquid having excellent abrasive properties, a method for producing the same, and an abrasive grain dispersion liquid.

Brief Description of the Drawings

[0011]

Figure 1

Embodiments for Carrying Out the Invention

[0012] [A particulate linked silica fine particle dispersion liquid (linked particle dispersion liquid) containing particulate linked silica fine particles having a structure in which silica primary fine particles are linked] The particulate linked silica fine particle dispersion liquid of the present invention is a particulate linked silica fine particle dispersion liquid containing particulate linked silica fine particles having a structure in which silica primary fine particles are linked, wherein the silica fine particles contained in the particulate linked silica fine particle dispersion liquid containing particulate linked silica fine particles having a structure in which the silica primary fine particles are linked satisfy the requirements of the following [1], and the particulate linked silica fine particles having a three-dimensional branched structure included in the silica fine particles satisfy the requirements of the following [2] and [3]. [1] The average particle diameter (D1) measured by the dynamic light scattering method of the silica fine particles is in the range of 50 nm or more and 600 nm or less. [2] The particulate linked silica fine particles having a three-dimensional branched structure have a chain-like structure and have at least one branch (a), and have a three-dimensional structure with respect to this structure. [3] The particulate linked silica fine particles having a three-dimensional branched structure contain an organic component.

[0013] Here, the fact that silica primary fine particles are linked means that adjacent silica primary fine particles are fixed to each other by a bond generated between adjacent silica primary fine particles. Here, the type of bond is not particularly limited, and examples thereof include chemical bonds such as siloxane bonds generated by a condensation reaction between surface silanol groups of adjacent silica primary fine particles. Hereinafter, the particulate linked silica fine particle dispersion liquid of the present invention is also referred to as "particulate linked silica fine particle dispersion liquid" or "linked particle dispersion liquid". The particulate-linked silica fine particles having a structure in which the silica primary fine particles of the present invention are linked are also referred to as "linked particles". The particulate-linked silica fine particles having a three-dimensional branched structure formed by linking the silica primary fine particles of the present invention are also referred to as "three-dimensional linked particles". Furthermore, the particulate-linked silica fine particles (linked particles) having a structure formed by linking silica primary fine particles other than the particulate-linked silica fine particles (three-dimensional linked particles) having a three-dimensional branched structure formed by linking the silica primary fine particles of the present invention are also referred to as "planar linked particles". The linked particles have a structure in which a large number of silica primary fine particles are bonded. In the linked particles, the smallest structural unit containing one silica primary fine particle may be referred to as a "unit structure" for the sake of convenience in the present application. Here, the "unit structure" includes one silica primary fine particle and a part of the neck portion formed between the silica primary fine particle and the silica primary fine particle adjacent to the silica primary fine particle. The particulate-linked silica fine particles in the present invention can also be referred to as particulate-linked silica fine particles having a structure in which the unit structures are linked. The same applies to the three-dimensional linked particles and the planar linked particles. As will be described later, the silica fine particle dispersion or the silica fine particles, which are one of the main raw materials for producing the particulate-linked silica fine particle dispersion of the present invention, may be referred to as the "silica fine particle dispersion as a raw material" and the "silica fine particles as a raw material", respectively. In addition, the silica primary fine particles other than the linked particles are referred to as "single particles". The silica fine particles contained in the particulate-linked silica fine particle dispersion of the present invention refer to all the silica fine particles (linked particles and single particles) contained in the particulate-linked silica fine particle dispersion. In the present invention, the characteristics of the particles may be specified using a transmission microscope photograph or a scanning microscope photograph. In this case, a transmission microscope image can be used in the same manner instead of the photograph. Similarly, a scanning microscope image can be used in the scanning microscope photograph.

[0014] The average particle diameter (D1) of the silica fine particles contained in the particle-linked silica fine particle dispersion liquid containing particle-linked silica fine particles having a structure in which the silica primary fine particles are linked is in the range of 50 nm or more and 600 nm or less, preferably in the range of 80 nm or more and 400 nm or less, and more preferably in the range of 100 nm or more and 350 nm or less, as measured by the dynamic light scattering method. If the average particle diameter (D1) is less than 50 nm, it may not be possible to obtain a sufficient polishing rate, which is not preferable. Further, if the average particle diameter (D1) exceeds 600 nm, the tendency for scratches to occur on the polished substrate increases, which is not preferable.

[0015] [Particle-linked silica fine particles (linked particles) having a structure in which silica primary fine particles are linked] The particle-linked silica fine particles (linked particles) having a structure in which the silica primary fine particles of the present invention are linked are composed of particle-linked silica fine particles having a three-dimensional branched structure (three-dimensionally linked particles) and particle-linked silica fine particles other than the particle-linked silica fine particles having a three-dimensional branched structure (planar linked particles).

[0016] Regarding the silica primary fine particles in the "particle-linked silica fine particles having a structure in which the silica primary fine particles are linked", it is preferable that the shape thereof is spherical or substantially spherical. Note that a small amount of particles of other shapes (for example, egg-shaped, cubic or rod-shaped particles) may be mixed together with such spherical particles or the like. The particle diameters of the silica primary fine particles may be uniform or may be different from each other. Here, the shape of the silica primary fine particles can be confirmed from a transmission electron micrograph (magnification: 200,000 times).

[0017] The average particle diameter (transmission electron micrograph, magnification 200,000 times) of the silica primary fine particles in the linked particles is preferably 5 nm or more and 600 nm or less, more preferably 20 nm or more and 400 nm or less, and even more preferably 60 nm or more and 300 nm or less. In the present application, such an average particle diameter is represented by the average particle diameter [F]. The measurement method of the average particle diameter [F] is as described below. When the average particle diameter of the silica primary particles in the linked particles is less than 5 nm, the linked particles obtained by aggregating the silica primary particles tend to be in a lump shape. Also, in polishing applications, sufficient polishing speed cannot be obtained, presumably because stress concentration on the polishing substrate cannot be achieved, which is not preferable. When the average particle diameter of the silica primary particles exceeds 600 nm, for example, in polishing applications, the contact area between the polishing substrate and the linked particles decreases significantly, sometimes leading to a decrease in the polishing speed. Also, scratches (linear marks) may easily occur on the polished surface. There is no significant difference between the average particle diameter of the silica primary particles in the three-dimensional linked particles and that of the silica primary particles in the planar linked particles.

[0018] [Particulate-linked silica fine particles having a three-dimensional branched structure (three-dimensional linked particles)] The particulate-linked silica fine particles having a three-dimensional branched structure in the present invention are characterized by having a chain-like structure with at least one branch (a) and a three-dimensional structure with respect to this structure. More specifically, as shown in FIG. 1, the particulate-linked silica fine particles have a chain-like structure (Ch) in which silica primary particles indicated by white circles are linked in a chain. Further, silica primary particles are linked to this chain-like structure (Ch) to have a branch (a). Here, the number of branches (a) may be one or more, and there is no particular limitation. The chain-like structure (Ch) and the branch (a) exist substantially on the same plane. And silica primary particles indicated by black circles are combined in a direction intersecting this plane and forming an angle (hereinafter also referred to as the "three-dimensional direction") to form a branch (b) or a terminal (c) so as to have a three-dimensional structure.

[0019] Having at least one branch (a) and a three-dimensional structure with respect to this structure specifically means at least one of the following structures (1) or (2). (1) A branch (b) extending in the three-dimensional direction with respect to the branch (a) (2) A terminal (c) extending in the three-dimensional direction with respect to the branch (a)

[0020] The term "chain-like" refers to an elongated structure formed by the connection of silica fine particles, which can also be referred to as a bent or linear shape. Note that a particle connection structure in which such chain-like particles are joined at both ends to form a ring shape, a network structure, a structure in which silica primary fine particles aggregate to form a tetrapod-like shape, and an irregular aggregate of silica primary fine particles (for example, a massive aggregate containing a plurality of silica primary fine particles) are not included in the scope of the chain-like structure.

[0021] The term "branch (a)" refers to a branched structure formed by the connection of the ends of silica primary fine particles or a connection body of silica primary fine particles in a direction other than the linear direction in particles excluding the silica primary fine particles at both ends of the three-dimensionally connected particles. (The chain-like portion containing the silica primary fine particles to which the branch (a) is connected in the three-dimensionally connected particles is referred to as the "main chain".) The term "branch (b)" refers to a branched structure formed by the connection of the ends of silica primary fine particles or a connection body of silica primary fine particles in a direction other than the linear direction in particles excluding the silica primary fine particles at both ends of the three-dimensionally connected particles, and refers to a branch extending in the three-dimensional direction with respect to the extension direction of the branch (a). The three-dimensional direction can be determined from a transmission electron micrograph as described below. The term "end (c)" refers to a bent structure formed by the connection of the ends of silica primary fine particles or a connection body of silica primary fine particles in a direction other than the linear direction in particles excluding the silica primary fine particles at both ends of the three-dimensionally connected particles, and refers to a bent structure extending in the three-dimensional direction with respect to the extension direction of the branch (a). Here, the three-dimensional direction can be determined from a transmission electron micrograph as described below. The average number of connections of the silica primary fine particles in the particle-connected type silica fine particles having the three-dimensional branched structure is preferably in the range of 5 or more and 20 or less.

[0022] The particle-connected type silica fine particles having the three-dimensional branched structure in the present invention have a structure that is chain-like as defined in requirement [2] and has at least one branch (a), and has a three-dimensional structure with respect to this structure. Such a three-dimensional structure can be confirmed using an electron micrograph (transmission electron micrograph, TEM micrograph) of the particle-connected type silica fine particle dispersion.

[0023] The three-dimensional linked particles of the present invention have branches (a) and (b) or a branch (a) and a terminal (c) as described above. Since the extending direction of the branch (a) and the extending direction of the branch (b) are in a three-dimensional structural relationship, and similarly, the extending direction of the branch (a) and the extending direction of the terminal (c) are also in a three-dimensional structural relationship, when the three-dimensional linked particles are applied as abrasive grains on a polishing substrate, during polishing, the three-dimensional linked particles of the present invention are likely to receive stress concentration at a plurality of contact points with the polishing machine substrate, so that it can contribute to the enhancement of the polishing rate. Furthermore, the abrasive grains composed of three-dimensional linked particles increase the dynamic contact area with the polishing substrate due to their rotational movement, so this can also contribute to the increase in the polishing rate.

[0024] In the present invention, the confirmation of the particle-linked silica fine particles having a three-dimensional branched structure is carried out as follows. A transmission electron micrograph (magnification: 200,000 times) of a particle-linked silica fine particle dispersion liquid (SiO2 concentration: 1% by mass, average particle diameter measured by the dynamic light scattering method in the range of 50 nm to 600 nm) containing particle-linked silica fine particles having a structure in which silica primary fine particles are linked is prepared. Among at least 200 particles of an arbitrary shape in which the particles are linked, the number of particles corresponding to the three-dimensional linked particles is measured, and the number ratio of the three-dimensional linked particles is calculated. The criteria for determining the three-dimensional linked particles are as follows. That is, for specific particle-linked silica fine particles, it is confirmed whether the following requirements (1) to (3) are satisfied. (1) The number of linked silica primary fine particles is 5 or more and has a chain structure (2) Among the particles constituting the main chain, there is at least one branch (branch (a)) bonded to a particle other than the terminal particle. (3) On the specific particle-linked silica fine particles, a portion with a darker shade can be confirmed to overlap compared to other primary particles. The particle-linked silica fine particles that satisfy the above requirements are determined to have a branch (b) extending in the three-dimensional direction or a terminal (c) extending in the three-dimensional direction with respect to the branch (a), and are defined as three-dimensional linked particles having a three-dimensional structure with respect to the branch (a).

[0025] [Organic component] The particle - linked silica fine particles of the present invention contain an organic component. Here, "contain" refers to encapsulation inside the particle - linked silica fine particles, but a part of the organic component may be adsorbed on the particle surface. In addition, in the particle - linked silica fine particle dispersion, a part of the organic component may be eluted into the dispersion.

[0026] The particle - linked silica fine particles of the present invention preferably encapsulate an organic component. Generally, the organic component is adsorbed on the particle surface. When the silica fine particles with the organic component adsorbed on the particle surface are used as abrasive grains, the organic component may act as a cushion layer between the abrasive substrate and the particles, which may reduce the polishing rate, so it is not preferable. Also, it is not preferable because the organic component desorbed from the silica fine particle surface may adsorb on the substrate to be polished and cause contamination. On the other hand, in the particle - linked silica fine particles of the present invention, since most of the organic component is encapsulated, there are advantages such as no reduction in the above - mentioned polishing rate and no contamination of the substrate. The organic component is derived from the organic polymer component added as a raw material in the production method of the present invention. In the particle - linked silica fine particles having a three - dimensional branched structure obtained through the production method of the present invention, the properties of the organic polymer may be maintained, or the properties of the organic polymer may not be maintained and, for example, it may be an organic compound.

[0027] Incidentally, that the particle - linked silica fine particles encapsulate an organic component inside can be confirmed, for example, by the following method. That is, it can be confirmed by measuring the COD (chemical oxygen demand) when the particle - linked silica fine particles are dissolved. The COD measurement value can be measured by the method described in the examples below. From the viewpoint that the particle - linked silica fine particles encapsulate an organic component inside, it is preferable that this COD measurement value is 1000 mg / L or more for 1 L of the solution in which 100 g of silica is dissolved.

[0028] The organic polymer component used in the production method of the present invention is not limited in its molecular structure and may be linear, planar-branched, or three-dimensional-branched. The organic polymer component is cationic and has a cationic functional group. Its structure contains a cationic functional group, but may also contain any one or all of an anionic functional group and a nonionic functional group. As described above, having a cationic functional group is preferable because it enables control of the surface charge of the silica fine particles. The weight average molecular weight of the organic polymer component is preferably 300 or more and 10,000 or less, more preferably 300 or more and 5,000 or less, and particularly preferably 300 or more and 2,000 or less. When the weight average molecular weight of the organic polymer component is below the above range, a large amount of the organic polymer component is required to promote the aggregation of the silica fine particles, which is not economically preferable. Also, when the weight average molecular weight of the organic polymer component exceeds the above range, the aggregation of the silica fine particles cannot be controlled, and it tends to be difficult to obtain the desired particles. The method for measuring the weight average molecular weight of the organic polymer component is not particularly limited, and a conventionally known method can be used. For example, light scattering method, aqueous size exclusion chromatography (SEC), gel permeation chromatography (GPC), and boiling point elevation method can be mentioned. Also, when the molecular weight is clear from information provided by the supplier, that information may be used.

[0029] The organic polymer component is not particularly limited, and examples include poly(diethylaminoethyl methacrylate) (PDEAEM), poly(dimethyldiallylammonium chloride) (PDMDAAC), and polyalkyleneimine. The polyalkyleneimine used in the present invention means, for example, polymers obtained by polymerizing alkyleneimines having 2 to 8 carbon atoms such as ethyleneimine, propyleneimine, butyleneimine, dimethylethyleneimine, pentyleneimine, hexyleneimine, heptyleneimine, and octyleneimine, and polymers chemically modified by reacting these with various compounds.

[0030] [In particulate linked silica fine particles having a three-dimensional branched structure29 [Si-NMR spectrum] When measuring the Si-NMR spectrum of the particulate-linked silica fine particles having a three-dimensional branched structure in the present invention, it is preferable to satisfy the following conditions. 29 When measuring the Si-NMR spectrum of the particulate-linked silica fine particles having a three-dimensional branched structure in the present invention, it is preferable to satisfy the following conditions. The ratio [(Q2+Q3) / Q4)] of the total peak area of Q2 and Q3 to the peak area of Q4 is preferably in the range of 1.0 or more and 2.0 or less. Although this mechanism is not clear, the present inventors presume that in the particle preparation process, the adsorption of the organic component to the silanol group inhibits the polycondensation reaction, and as a result, when the value of [(Q2+Q3) / Q4)] exceeds 1.0. That is, based on the above hypothesis and the fact that the particulate-linked silica fine particles of the present invention contain an organic component, since the value of [(Q2+Q3) / Q4)] is in this range, it is presumed that the polycondensation reaction has not proceeded inside the particulate-linked silica fine particles of the present invention as compared with conventionally known silica fine particles. Since the polycondensation reaction has not proceeded, it is presumed that the particulate-linked silica fine particles of the present invention have a relatively sparse particle density. That is, the present inventors presume that when used as abrasive grains, the number of particles can be increased, and more specifically, the contact area between the particulate-linked silica fine particles and the polishing substrate can be increased, and a high polishing rate can be obtained. On the other hand, if it exceeds 2.0, the decrease in particle hardness accompanying the decrease in particle density is remarkable, and particle breakage occurs when used as abrasive grains, resulting in a decrease in polishing performance, which is not preferable.

[0031] [Average longest diameter (DLa) in the longitudinal direction of particulate-linked silica fine particles having a three-dimensional branched structure] The particulate-linked silica fine particles (three-dimensionally linked particles) having a three-dimensional branched structure in the present invention preferably satisfy the following requirement [4]. Requirement [4] 50 nm ≦ DLa ≦ 1,000 nm Here, the average longest diameter (DLa) in the longitudinal direction of the particulate-linked silica fine particles having a three-dimensional branched structure is a value obtained by measuring and averaging the longest diameters (DL) of 50 particulate-linked silica fine particles having a three-dimensional branched structure. Specifically, for the particle-connected silica fine particles having a three-dimensional branched structure, the longest diameter (DL) in the length direction is measured for 50 particles corresponding to the three-dimensional connected particles using a scanning electron microscope (200,000 times magnification) of a silica fine particle dispersion (SiO2 concentration: 0.05% by mass), and the average value is calculated for each of the longest diameters (DL).

[0032] It is preferable that the average longest diameter (DLa) in the length direction of the three-dimensional connected particles is 50 nm or more and 1,000 nm or less, because an excellent polishing rate can be obtained. If the average longest diameter (DLa) in the length direction of the three-dimensional connected particles is less than 50 nm, a sufficient polishing rate may not be obtained, which is not preferable. Further, if the average longest diameter (DLa) in the length direction of the three-dimensional connected particles exceeds 1,000 nm, scratches are likely to occur on the polished substrate, which is not preferable. The longest diameter (DLa) in the length direction of the three-dimensional connected particles is more preferably 80 nm or more and 600 nm or less, and most preferably 100 nm or more and 600 nm or less.

[0033] [Average diameter (DTa) in the thickness direction of the particle-connected silica fine particles having a three-dimensional branched structure] The particle-connected silica fine particles (three-dimensional connected particles) having a three-dimensional branched structure in the present invention preferably satisfy the following requirement [5]. Requirement [5]: 10 nm ≤ DTa ≤ 800 nm Here, the average diameter DTa in the thickness direction of the particle-connected silica fine particles (three-dimensional connected particles) having a three-dimensional branched structure means the value obtained by further averaging the average value of the maximum values (DTmax) in each particle for 50 three-dimensional connected particles ([the sum of DTmax for 50 three-dimensional connected particles] / 50). The three-dimensional connected particles have at least two minimum values (DTmin) and maximum values (DTmax) in the distance in the thickness direction in terms of the outer shape. The thickness direction of the particle-connected silica fine particles having a three-dimensional branched structure refers to the direction orthogonal to the longest diameter (DL) in the length direction. In the particulate-linked silica fine particles having a three-dimensional branched structure, the outer diameter DT in the thickness direction refers to the distance between two intersection points where the outer edge of the particle intersects a line segment in the thickness direction. The "outer edge of the particulate-linked silica fine particles" refers to the contour of the particulate-linked silica fine particles when the particulate-linked silica fine particles are viewed in plan (photographic projection view) using a scanning microscope photograph or the like (SEM photograph or the like). The outer diameter DT in the thickness direction of the particulate-linked silica fine particles having a three-dimensional branched structure is measured using a scanning electron microscope (200,000 times magnification).

[0034] It is preferable that the average diameter (DTa) in the thickness direction of the three-dimensional linked particles is 10 nm or more and 800 nm or less, as this causes no practical inconvenience. If the average diameter (DTa) in the thickness direction of the three-dimensional linked particles is less than 10 nm, it is not preferable because it is accompanied by significant thickening of the dispersion liquid, causing inconvenience in handling. Also, if the average diameter (DTa) in the thickness direction of the three-dimensional linked particles exceeds 800 nm, the sedimentation property of the particles increases, causing inconvenience in handling, so it is not preferable. The average longest diameter (DTa) in the thickness direction of the three-dimensional linked particles is more preferably 20 nm or more and 600 nm or less. Even more preferably, it is 40 nm or more and 600 nm or less, and most preferably 60 nm or more and 600 nm or less.

[0035] It is preferable that the average longest diameter (DLa) in the length direction of the particulate-linked silica fine particles having a three-dimensional branched structure in the present invention is in the range of 50 nm or more and 1000 nm or less, and the average diameter (DTa) in the thickness direction thereof is in the range of 10 nm or more and 800 nm or less.

[0036] [Coefficient of variation (C.V.) of the diameter (DT) in the thickness direction of the particulate-linked silica fine particles having a three-dimensional branched structure] The particulate-linked silica fine particles (three-dimensional linked particles) having a three-dimensional branched structure in the present invention preferably satisfy the following requirement [6]. Requirement [6] 10% ≦ C.V. ≦ 40% The coefficient of variation and the average coefficient of variation (C.V.) of the diameter (DT) in the thickness direction of the particulate-connected silica fine particles having a three-dimensional branched structure are determined as follows. (1) Use the scanning electron micrograph used when obtaining the longest diameter DL in the particulate-connected silica fine particles having a three-dimensional branched structure. (2) Bisect the longest diameter DL, obtain two intersection points where the orthogonal line segments intersect the outer edge of the particle, and define the line segment connecting the two intersection points as DT. (3) Perform the measurement of (2) above for 50 arbitrarily selected three-dimensionally connected particles, and define the average value (total of 50 DT values / 50) as the average diameter DTa in the thickness direction. (4) Perform the measurement of (2) above for 50 arbitrarily selected three-dimensionally connected particles, obtain the coefficient of variation for each DT value of the 50 three-dimensionally connected particles, and define the averaged value as the average coefficient of variation (C.V.). It is preferable that the average coefficient of variation (C.V.) is in the range of 10% or more and 40% or less because a good polishing rate can be obtained. When the average coefficient of variation (C.V.) is less than 10%, the formation of branches is insufficient and the desired polishing characteristics cannot be obtained, which is not preferable. Also, when the average coefficient of variation (C.V.) exceeds 40%, the contact between the particles and the substrate becomes non-uniform, so the desired polishing characteristics cannot be obtained, and the tendency for scratches to occur on the polished substrate increases, which is not preferable. More preferably, the average coefficient of variation (C.V.) is in the range of 15% or more and 35% or less.

[0037] [Neck portion of particulate-connected silica fine particles having a three-dimensional branched structure] In the three-dimensionally connected particles of the present invention, depending on the degree of silica reinforcement treatment such as a silicic acid solution after the generation of the three-dimensionally connected particles, there are differences in the neck portions formed between adjacent silica primary fine particles. Draw a straight line C that circumscribes both of the adjacent silica primary fine particles (p1) and silica primary fine particles (p2), obtain a line segment perpendicular to the straight line C from the joint portion of the silica primary fine particles (p1) and (p2), and define that line segment as the neck portion depth (L) [nm]. Define Ls, Lm, and F as follows. F: Average particle diameter of silica primary particles in three-dimensional linked particles (transmission electron microscope) L: Neck depth Ls: Average value of neck depth in the same three-dimensional linked particles Lm: Average value of neck depth in 50 three-dimensional linked particles At this time, Lm preferably satisfies the range represented by the following mathematical formula (2-1). 0 ≦ Lm ≦ F / 3 ··· (2-1) When Lm is within the above range, the neck between the primary particles is sufficiently reinforced with silica, and even when subjected to the load during polishing, the particle connection structure and the three-dimensional structure are retained. Therefore, a high contact area between the particles and the polishing substrate can be obtained, and the desired polishing performance can be obtained. On the other hand, when the value of Lm is larger than the value of F / 3, that is, when the average value (Lm) of the neck depth is larger than one-third of the average particle diameter (F) of the silica primary particles, the neck depth between the primary particles is not sufficiently reinforced with silica, and the structure of the three-dimensional linked particles may collapse due to the load during polishing, resulting in a decrease in the polishing rate. When Lm exceeds F / 2, it cannot be regarded as a particle connection state. Lm more preferably satisfies the range represented by the following mathematical formula (2-2), and even more preferably satisfies the range represented by the following mathematical formula (2-3). 0 < Lm < F / 6 ··· (2-2) 0 < Lm < F / 9 ··· (2-3)

[0038] [Coefficient of variation of average neck depth (C.V.(Lm)) of particle-linked silica fine particles having a three-dimensional branched structure] The particle-linked silica fine particles (three-dimensional linked particles) having a three-dimensional branched structure in the present invention preferably satisfy the following requirements. 0% ≦ C.V.(Lm) ≦ 40% Here, C.V.(Lm) is obtained by calculating Ls of each particle as described above for 50 three-dimensional linked particles, and is the coefficient of variation among the obtained 50 values. C.V.(Lm) is more preferably in the range of 0% or more and 35% or less, and even more preferably in the range of 0% or more and 30% or less. When C.V.(Lm) is within the above range, neck reinforcement is uniform, particle disintegration during polishing can be suppressed, and the polishing rate becomes stable. When C.V.(Lm) exceeds 40%, that is, when the variation in the neck depth between particles is large, the contact area between each particle and the substrate also varies. For this reason, the polishing rate may decrease and defects such as scratches may easily occur.

[0039] [Method for Measuring Neck Depth] At an arbitrary location of the three-dimensional connected particles, draw a straight line C that circumscribes both of the adjacent silica primary fine particles (p1) and silica primary fine particles (p2), and obtain a line segment perpendicular to the straight line C from the joint of the silica primary fine particles (p1) and (p2). Let the line segment be the neck portion depth (L) [nm]. At three arbitrary locations of the same three-dimensional connected particles, obtain the above-mentioned neck portion depth (L) [nm], and calculate their average value (Ls) [nm]. Perform this measurement and calculation for 50 three-dimensional connected particles, and obtain their average value (Lm) [nm].

[0040] [Average Number of Connected Silica Primary Fine Particles in Particle-Connected Silica Fine Particles with a Three-Dimensional Branch Structure] The average number of connected silica primary fine particles in the three-dimensional connected particles of the present invention is preferably in the range of 5 or more and 20 or less. If the average number of connected particles is less than 5, it is not preferable because a sufficient dynamic contact area cannot be obtained and a desired polishing rate cannot be achieved. Also, if the average number of connected particles exceeds 20, it becomes more of an aggregate form rather than a connected type, which may cause defects and is not preferable. The average number of connected silica primary fine particles in the three-dimensional connected particles of the present invention is more preferably in the range of 5 or more and 15 or less.

[0041] The average number of connected silica primary fine particles in the three-dimensional connected particles of the present invention is measured using a scanning electron microscope photograph (200,000 times magnification) of the three-dimensional connected particle dispersion liquid. Using a scanning electron microscope photograph, visually count the number of silica primary particles linked to each three-dimensional linked particle. Then, take the average value of the number of links of 50 three-dimensional linked particles as the average number of links.

[0042] [Silica primary particles in particle-linked silica fine particles having a three-dimensional branched structure] The average particle size range of the silica primary particles in the three-dimensional linked particles is the same as that of the silica primary particles in the linked particles. That is, the average particle size of the silica primary particles in the three-dimensional linked particles is preferably 5 nm or more and 600 nm or less, more preferably 20 nm or more and 400 nm or less, and even more preferably 60 nm or more and 300 nm or less. When the average particle size is less than 5 nm, the linked particles obtained by aggregation of primary particles tend to be in a lump shape. Also, in the case of polishing applications, sufficient polishing speed cannot be obtained, presumably because stress concentration cannot be achieved, which is not preferable. When the average particle size exceeds 600 nm, for example, in polishing applications, the contact area decreases significantly, sometimes leading to a decrease in the polishing speed. Also, when the average particle size exceeds 600 nm, for example, scratches (linear marks) may occur on the polished surface.

[0043] [Particle-linked silica fine particles (planar linked particles) other than particle-linked silica fine particles (three-dimensional linked particles) having a three-dimensional branched structure] The planar linked particles of the present invention are particle-linked silica fine particles (linked particles) other than particle-linked silica fine particles (three-dimensional linked particles) having a three-dimensional branched structure. Therefore, particles in which two or more silica primary particles are linked and which are other than three-dimensional linked particles are included in the planar linked particles. For example, those in which two silica primary particles are linked are all included in the planar linked particles because a branched structure cannot be assumed. Also, the planar linked particles are not limited to those linked in a chain-like manner like the three-dimensional linked particles. For example, the planar linked particles include those in which part or all of the silica primary particles are linked in a ring shape in the structure of the linked particles.

[0044] [Silica fine particles other than particle-linked silica fine particles (linked particles)] The silica fine particles (single particles) other than the particle-linked silica fine particles (linked particles) of the present invention include those other than those in which two or more silica primary fine particles are linked. The silica fine particles (single particles) mainly consist of unreacted silica primary fine particles in the silica primary fine particles used as reactants in order to produce linked particles.

[0045] [Proportions of Ca, Mg, Al, and Fe contained in the silica fine particles of the particle-linked silica fine particle dispersion] In the particle-linked silica fine particle dispersion of the present invention, the proportions of Ca, Mg, Al, and Fe contained in the silica fine particles are preferably 25 ppm or less, 25 ppm or less, 150 ppm or less, and 50 ppm or less, respectively. The content ratio of each element is expressed as the ratio of the mass of each element contained per unit mass of the silica fine particles. The silica fine particles of the particle-linked silica fine particle dispersion of the present invention are silica primary fine particles or those in which these are bonded by silica. For this reason, for example, they do not contain binder components such as CaO, MgO, Al2O3, and Fe2O3. Therefore, when the particle-linked silica fine particle dispersion containing the silica fine particles of the present invention is applied to polishing applications of semiconductor devices such as semiconductor substrates or wiring substrates, there is a low risk of problems of metal contamination caused by these binder components. The Ca content in the silica fine particles in the particle-linked silica fine particle dispersion is more preferably 10 ppm or less, the Mg content is more preferably 10 ppm or less, the Al content is more preferably 60 ppm or less, and the Fe content is more preferably 20 ppm or less.

[0046] The particle-linked silica fine particle dispersion of the present invention preferably contains 5% by number or more and 50% by number or less of three-dimensional linked particles as its dispersed substance. The number ratio of the three-dimensional linked particles is preferably in the range of 5% by number or more and 50% by number or less. More preferably, it is in the range of 5% by number or more and 30% by number or less, and even more preferably, it is in the range of 5% by number or more and 25% by number or less. Also, the ratio of the planar linked particles is preferably 50% by number or more and 95% by number.

[0047] When the number ratio of the three-dimensional linked particles is in the range of 5% to 50% by number, when the particulate-linked silica fine particle dispersion of the present invention is applied to polishing applications, it can effectively contribute to the increase in the polishing rate. When the number ratio of the three-dimensional linked particles is less than 5% by number, among the abrasive grains, since the ratio of the three-dimensional linked particles having the three-dimensional structure is low, although the surface roughness of the substrate after polishing becomes low, the polishing rate also decreases. When the number ratio of the three-dimensional linked particles exceeds 50% by number, among the abrasive grains, the ratio of the three-dimensional linked particles having the three-dimensional structure is excessive, and although the polishing rate increases, problems such as the generation of scratches on the polishing substrate and the deterioration of the surface roughness are likely to occur. When the number ratio of the three-dimensional linked particles is 50% or less by number, single particles, particles with low connectivity, and planar linked particles present in excess of 50% by number improve the roughness of the polishing substrate, and the three-dimensional linked particles of 50% or less by number exhibit a high polishing rate. Therefore, it is possible to achieve both a high polishing rate and a good surface roughness.

[0048] The percentage by number of the three-dimensional linked particles is determined as follows. From a transmission microscope photograph (200,000 times magnification) of a linked particle dispersion liquid (solid content concentration: 0.05% by mass), 200 particles having at least a shape in which particles are linked are arbitrarily selected. Each of the 200 selected particles is classified as either a three-dimensional linked particle or a planar linked particle. Then, the value obtained by dividing the number of three-dimensional linked particles by 200 is defined as the percentage by number of the three-dimensional linked particles.

[0049] In the particulate-linked silica fine particle dispersion of the present invention, the volume percentage of the three-dimensional linked particles is preferably in the range of 40% to 95% by volume. When the volume ratio of the three-dimensional linked particles is in the range of 40% to 95% by volume, when the particulate-linked silica fine particle dispersion of the present invention is applied to polishing applications, it can effectively contribute to the increase in the polishing rate. When the volume ratio of the three-dimensional linked particles is less than 40% by volume, among the abrasive grains, the ratio of the three-dimensional linked particles having the three-dimensional structure is low, and the contribution to the increase in the polishing rate is also small. When the volume ratio of the three-dimensional linked particles exceeds 95% by volume, among the abrasive grains, the ratio of the three-dimensional linked particles having the three-dimensional structure is excessive, and although the polishing rate increases, problems such as scratch generation on the polished substrate are likely to occur. The volume ratio of the three-dimensional linked particles is preferably 45% by volume or more and 90% by volume or less, more preferably 50% by volume or more and 86% by volume or less.

[0050] The method for obtaining the volume% (W) of the three-dimensional linked particles is as described below.

[0051] In addition to the three-dimensional linked particles and the planar linked particles, the particle-linked silica fine particle dispersion of the present invention may contain unlinked single particles as long as it does not significantly affect the effects of the invention. For example, when used as an abrasive grain, the ratio of the volume of the single particles to the volume of the particle-linked silica fine particles is desirably 55 (volume parts) or less with respect to the former 100 (volume parts). (Here, the volume of the particle-linked silica fine particles means the sum of the volume of the three-dimensional linked particles and the volume of the planar linked particles.) If the ratio of the volume of the single particles to the volume of the particle-linked silica fine particles is within the above range, the effects of the present invention will not be impaired. When the volume ratio of the single particles exceeds 55 (volume parts), the ratio of the three-dimensional linked particles having the three-dimensional structure among the abrasive grains is relatively low, and for example, the effect on the increase in the polishing rate is also difficult to occur. Also, the ratio of the number of single particles to the number of particle-linked silica fine particles is desirably 210 (number parts) or less with respect to the former 100 (number parts). (Here, the number of particle-linked silica fine particles means the sum of the number of three-dimensional linked particles and the number of planar linked particles.) If the ratio of the number of single particles to the number of particle-linked silica fine particles is within the above range, the effects of the present invention will not be impaired. When the number ratio of the single particles exceeds 210 (number parts), the ratio of the three-dimensional linked particles having the three-dimensional structure among the abrasive grains is relatively low, and for example, the effect on the increase in the polishing rate is also difficult to occur.

[0052] The solid content concentration of the linked particle dispersion is preferably 2% by mass or more and 50% by mass or less. If it is within this range, sedimentation of particles over time is less likely to occur, and it can also be applied to storage or transportation. If it exceeds 50% by mass, aggregation of particles and accompanying sedimentation are likely to occur. Especially when the linked particle dispersion is applied to polishing applications, such particle aggregation or sedimentation may impair the stability of the polishing abrasive grain dispersion and may reduce the polishing speed and efficiency. Also, in the container for storing the polishing abrasive grain dispersion or in the supply process for polishing, the polishing abrasive grain dispersion adhering to the inner wall of the container or supply device is likely to dry and form aggregates, which may mix back into the polishing abrasive grain dispersion and cause scratches during the polishing process. If it is less than 2% by mass, concentration is required when applying the linked particle dispersion to various applications, which is not practical. The solid content concentration is more preferably 5% by mass or more and 30% by mass or less. Here, the solid content concentration means the concentration of the dispersed substance in the linked particle dispersion. Specifically, it is the concentration based on the mass of the silica fine particles (the total mass of the linked particles (three-dimensional linked particles and planar linked particles) and single particles).

[0053] Regarding the solvent or dispersion medium of the linked particle dispersion, it may be any of water, an organic solvent, or a mixed solvent thereof. Examples of the organic solvent include water-soluble organic solvents such as alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, etc.), ethers, esters, and ketones.

[0054] [Method for producing a particle-linked type silica fine particle dispersion] <Step 1> Step 1 is a step of adding a cationic organic polymer component to a silica fine particle dispersion (SiO2 concentration of 1.5% by mass or more and 30% by mass or less) within the following ratio range (WA / WS1), then heating to 40°C or more and 98°C or less, and holding for 0.5 hours or more to obtain a particle-linked type silica fine particle dispersion. 0.01 ≦ WA / WS1 ≦ 0.3 (Here, WS1 is the mass (g) of silica in the silica fine particle dispersion, and WA is the mass (g) of the cationic organic polymer component.)

[0055] The silica fine particle dispersion used in Step 1 is one in which silica fine particles are dispersed in a dispersion medium. Examples of the dispersion medium include the solvent or dispersion medium of the linked particle dispersion. The silica fine particles preferably have the same shape and the same average particle diameter as the silica primary fine particles in the linked particles. Also, the concentrations of Ca, Mg, Al, and Fe contained in the silica fine particles are preferably as follows in terms of the masses of Ca, Mg, Al, and Fe per unit mass of the silica fine particles. Ca: 25 ppm or less Mg: 25 ppm or less Al: 150 ppm or less Fe: 50 ppm or less

[0056] The SiO2 concentration of the silica fine particle dispersion used in Step 1 is preferably 1.5 mass% or more and 30 mass% or less. When the SiO2 concentration of the silica fine particle dispersion is less than 1.5 mass%, the low SiO2 concentration affects and makes it difficult to form a linked structure of silica particles. Also, when the SiO2 concentration exceeds 30 mass%, the linking of silica particles occurs disorderly, and thus the particle structure tends to be uncontrollable. The SiO2 concentration of the silica fine particle dispersion used in Step 1 is more preferably in the range of 4 mass% or more and 18 mass% or less.

[0057] In the silica fine particle dispersion used in Step 1, the SiO2 / Na2O (molar ratio) is not restricted, and those containing no Na may be used.

[0058] As a method of desalting in Step 1, a method of exchanging Na + ions with H + ions using a cation exchange resin can be mentioned. Examples of the cation exchange resin include strongly acidic cation exchange resins or weakly acidic cation exchange resins, and resins having a structure substituted with -SO3H or -COOH, etc. The pH of the silica fine particle dispersion used in Step 1 is not particularly limited as long as the silica fine particle dispersion is stable. The pH of the silica fine particle dispersion used in Step 1 may be 2 or more and 12 or less. The pH adjustment can be performed, for example, by ion exchange with Na + ions.

[0059] The cationic organic polymer component used in Step 1 is added to the silica fine particle dispersion at a ratio of WA / WS1 of 0.01 or more and 0.3 or less (where WS1 is the mass (g) of silica in the silica fine particle dispersion and WA is the mass of the cationic organic polymer component). When a pH buffer or a pH adjuster is used within the above range of WA / WS1, three-dimensional linked particles and planar linked particles are likely to be generated due to the action of the buffer or the pH adjuster. When WA / WS1 is less than 0.01, it is difficult to generate planar linked particles and three-dimensional linked particles. Further, when WA / WS1 exceeds 0.3, the pH buffer becomes excessive, and particle aggregation is likely to occur, and massive particles are likely to be generated. WA / WS1 is more preferably 0.015 or more and 0.07 or less.

[0060] The cationic organic polymer component is dissolved in water and used as an aqueous solution. This organic polymer component is as described above.

[0061] In the method for producing the particle-linked silica fine particle dispersion of the present invention, it is preferable not to use a conventionally known inorganic flocculant. By using an organic polymer component, particularly an organic polymer component containing a cationic functional group, the charge on the surface of the silica fine particles can be controlled. And particle-linked silica fine particles having a desired morphology can be obtained without using an inorganic flocculant. Furthermore, the content of metal impurities can be reduced as compared with silica fine particles obtained by conventionally known methods, and it is particularly suitable for preventing contamination of a polishing substrate or a polishing apparatus in semiconductor polishing applications. The inventors interpret the mechanism of the present invention as follows. In the manufacturing method and step 1 of the present invention, the organic polymer component added to the raw material silica fine particle dispersion liquid at a predetermined ratio coats the surface of the silica fine particles partially or entirely, and furthermore, a part of the organic polymer component also exists in the solvent. The silica fine particles coated with the organic polymer component have a reduced repulsive force between particles due to the action of the organic polymer component, the absolute value of the surface potential becomes smaller, and they are in a more unstable state and prone to aggregation. Furthermore, the association of the coated silica fine particles progresses by the heat treatment in step 1, and silica fine particle aggregates (particle-linked type silica fine particles having a branched and three-dimensional structure) having a branched and three-dimensional structure are generated. In step 2 of the manufacturing method of the present invention, by adding silicic acid to the silica fine particle aggregates having the above-mentioned branched and three-dimensional structure under predetermined conditions, particle growth proceeds while filling the necks between adjacent silica fine particles in the associated silica fine particles having a branched and three-dimensional structure. In the above-mentioned silicic acid addition treatment, a silica component is deposited on the organic polymer component adsorbed on the particle surface, and as a result, particle-linked type silica fine particles in which an organic component derived from the organic polymer component is encapsulated inside the particles are obtained. On the other hand, the adsorption of the organic polymer component present in the solvent progresses with respect to the particle surface during particle growth, resulting in an increase in the surface potential, and a secondary association occurs in which the association of silica fine particles progresses even during particle growth. Therefore, the development of the branched and three-dimensional structure of the particle-linked type silica particles of the present invention is further promoted. Note that it is not necessarily required that all of the organic polymer component be encapsulated in the particle-linked type silica fine particles, and there is also a state adsorbed on the particle surface.

[0062] In step 1, if necessary, a pH buffer and a pH adjuster may be used. As the pH buffer, it is desirable to use a known inorganic or organic pH buffer. Examples of the pH buffer include ammonium acetate, sodium acetate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, disodium phosphate, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, and ammonium hydroxide. Among these, ammonium acetate or sodium acetate is particularly preferred. In addition, as the pH adjuster, it is desirable to use a known inorganic or organic pH adjuster. Examples of the pH adjuster include, as acids, acetic acid, formic acid, carbonic acid, hydrochloric acid, nitric acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, sulfuric acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, and hexametaphosphoric acid. Examples of the base include hydroxides of alkali metals such as potassium hydroxide, hydroxides of alkaline earth metals, and ammonia. Among these, potassium hydroxide or ammonia is preferred in terms of easy availability.

[0063] The pH after adding the total amount of the cationic organic polymer component is preferably in the range of 9.0 or more and 12.0 or less.

[0064] [Treatment such as heating (generation of three-dimensional linked particles)] It is preferable to heat the silica fine particle dispersion liquid whose pH is adjusted with a pH buffer material or a pH adjuster to 40°C or more and 98°C or less, and hold it for, for example, 0.5 hours or more and 64 hours or less. By heating, a bond by SiO2 is formed between adjacent silica primary fine particles, and linked particles are generated. If the heating temperature is less than 40°C, the linking reaction is difficult to promote and desired particle-linked silica fine particles cannot be obtained, which is not preferable. If the heating temperature exceeds 98°C, agglomerates are likely to occur and desired particle-linked silica fine particles cannot be obtained, which is not preferable. In addition, if the holding time is less than 0.5 hours, the coupling reaction will not proceed sufficiently, which is not preferable. Also, if the holding time exceeds 64 hours, the cost of the process will be high, which is not economically preferable. In the present invention, for the sake of convenience, the particulate-connected silica fine particle dispersion obtained only through Step 1 is referred to as particulate-connected silica fine particle dispersion (I), and the particulate-connected silica fine particle dispersion obtained through Step 1 and Step 2 may be referred to as particulate-connected silica fine particle dispersion (II).

[0065] <Step 2> In the connected particles obtained in Step 1, a bond by SiO2 is formed between adjacent silica primary fine particles, but the bonded part (hereinafter also referred to as "neck") is small and brittle. Therefore, it is preferable to grow the bonded part and strengthen the bond between adjacent silica primary fine particles. Therefore, for the purpose of growing the neck part, it is preferable to perform Step 2, which is a step of growing particles in particular, such as aging by heating or reinforcement by silica.

[0066] In Step 2, for the particulate-connected silica fine particle dispersion obtained in Step 1, it is adjusted to pH 10.0 or higher by adding an alkali, and then an acidic silicic acid solution is continuously or intermittently added so as to have the following ratio (WF / WS2), and a treatment for growing the particles is performed. 0.01 ≦ WF / WS2 ≦ 20 (Here, WS2 is the mass (g) of silica in the particulate-connected silica fine particle dispersion, and WF is the mass (g) of silica in the acidic silicic acid solution.)

[0067] As the alkaline component, ammonia, water glass, etc. can be used. The alkaline component can also be used in the form of a solution. The solvent for dissolving the alkaline component includes the solvent or dispersion medium of the connected particle dispersion. The solvent is preferably the dispersion medium used in Step 1, and more preferably water. The SiO2 concentration of the particulate-connected silica fine particle dispersion adjusted to pH 10 or higher is preferably 1% by mass or more and 30% by mass or less.

[0068] In Step 2, an acidic silicic acid solution is continuously or intermittently added to the particulate linked silica fine particle dispersion adjusted to pH 10 or higher in the range of 0.01 or more and 20 or less of WF / WS2. When WF / WS2 is less than 0.01, the growth of the linked portions of the particulate linked silica fine particles is insufficient, and thus the desired polishing characteristics cannot be obtained, which is not preferable. Also, when WF / WS2 exceeds 20, the shape of the obtained particulate linked silica fine particles may approach a spherical shape and the linked shape may not be maintained, which is not preferable. Since the temperature in Step 2 is a reaction for forming silica, it depends on the concentration of the reactants, but is preferably 70°C or higher and 98°C or lower. The addition of the acidic silicic acid solution in Step 2 can be performed continuously or intermittently. By adding the acidic silicic acid solution, it is preferable to change the concentration to form silica.

[0069] The acidic silicic acid solution is obtained by dissolving an alkali metal silicate (such as sodium silicate) in water and exchanging the alkali metal ions with hydrogen ions. Examples of the method for exchanging the alkali metal ions with hydrogen ions include using a cation exchange resin. The acidic silicic acid solution can be used if the pH is 6 or lower. As the SiO2 concentration of the acidic silicic acid solution, those of 1% by mass or more and 6% by mass or less can be used. When the SiO2 concentration is less than 1% by mass, a large amount of the acidic silicic acid solution to be added is required, which is not economically preferable. Also, when it is 6% by mass or more, the acidic silicic acid solution itself is unstable, which is not preferable. The SiO2 concentration is more preferably 1% by mass or more and 5% by mass or less.

[0070] <Step 3> From the viewpoint of further growing the particles (particularly the neck portions in the particles), Step 3 may be further performed. Step 3 is a step of performing a pH adjustment treatment to pH 10.0 or higher on the particulate linked silica fine particle dispersion that has been subjected to Step 2, and then continuously or intermittently adding an acidic silicic acid solution to perform a treatment for growing the particles. The operation of Step 3 is almost the same as that of Step 2. For example, by further performing Step 3 on the particulate-connected silica fine particle dispersion (II) obtained in Step 2, the connected particles can be further grown (particularly, the neck portion can be grown). Note that Step 3 may be repeated multiple times from the above viewpoint.

[0071] [Abrasive grain dispersion containing particulate-connected silica fine particle dispersion] The abrasive grain dispersion (also referred to as "polishing composition") containing the connected particle dispersion of the present invention can further contain other components. As the other components, one or more components selected from a polishing accelerator, a surfactant, a hydrophilic compound, a heterocyclic compound, a pH adjuster, and a pH buffer can be used.

[0072] Examples of the polishing accelerator include acids such as sulfuric acid, nitric acid, phosphoric acid, oxalic acid, and hydrofluoric acid, or sodium salts, potassium salts, ammonium salts of these acids, and mixtures thereof. In the case of a polishing composition containing these polishing accelerators, when polishing a work material composed of a composite component, by accelerating the polishing rate of a specific component of the work material, a flat polishing surface can be finally obtained.

[0073] When the polishing composition according to the present invention contains a polishing accelerator, its content is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less. Surfactant and / or hydrophilic compound To improve the dispersibility and stability of the polishing composition, a cationic, anionic, nonionic, or amphoteric surfactant or hydrophilic compound can be added.

[0074] Both the surfactant and the hydrophilic compound have the effect of reducing the contact angle with the work surface and have the effect of promoting uniform polishing. As the surfactant and / or hydrophilic compound, for example, those selected from the following group can be used.

[0075] Examples of anionic surfactants include carboxylates, sulfonates, sulfate esters, and phosphate esters. Examples of carboxylates include soaps, N-acyl amino acid salts, polyoxyethylene or polyoxypropylene alkyl ether carboxylates, and acylated peptides. Examples of sulfonates include alkyl sulfonates, alkyl benzene and alkyl naphthalene sulfonates, naphthalene sulfonates, sulfosuccinates, α-olefin sulfonates, and N-acyl sulfonates. Examples of sulfate esters include sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, and alkyl amide sulfates. Examples of phosphate esters include alkyl phosphates, polyoxyethylene or polyoxypropylene alkyl allyl ether phosphates.

[0076] Examples of cationic surfactants include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium chloride salts, benzethonium chloride, pyridinium salts, and imidazolinium salts. Examples of amphoteric surfactants include carboxybetaine type, sulfobetaine type, aminocarboxylates, imidazolinium betaines, lecithin, and alkylamine oxides.

[0077] Examples of nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type. Examples of ether type surfactants include polyoxyethylene alkyl and alkylphenyl ethers, alkyl allyl formaldehyde condensed polyoxyethylene ethers, polyoxyethylene polyoxypropylene block polymers, and polyoxyethylene polyoxypropylene alkyl ethers. Examples of ether ester type surfactants include polyoxyethylene ethers of glycerin esters, polyoxyethylene ethers of sorbitan esters, and polyoxyethylene ethers of sorbitol esters. Examples of ester type surfactants include polyethylene glycol fatty acid esters, glycerin esters, polyglycerin esters, sorbitan esters, propylene glycol esters, sucrose esters. Examples of nitrogen-containing type surfactants include fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amides, etc. In addition, fluorine-based surfactants, etc. may be mentioned.

[0078] As the surfactant, an anionic surfactant or a nonionic surfactant is preferred. Examples of the salt include ammonium salts, potassium salts, sodium salts, etc., and ammonium salts and potassium salts are particularly preferred.

[0079] Furthermore, as other surfactants, hydrophilic compounds, etc., esters (such as glycerin esters, sorbitan esters, and alanine ethyl esters), ethers (such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol alkyl ethers, polyethylene glycol alkenyl ethers, alkyl polyethylene glycols, alkyl polyethylene glycol alkyl ethers, alkyl polyethylene glycol alkenyl ethers, alkenyl polyethylene glycols, alkenyl polyethylene glycol alkyl ethers, alkenyl polyethylene glycol alkenyl ethers, polypropylene glycol alkyl ethers, polypropylene glycol alkenyl ethers, alkyl polypropylene glycols, alkyl polypropylene glycol alkyl ethers, alkyl polypropylene glycol alkenyl ethers, and alkenyl polypropylene glycols), polysaccharides (such as alginic acid, pectic acid, carboxymethyl cellulose, curdlan, and pullulan), amino acid salts (such as glycine ammonium salts and glycine sodium salts), polycarboxylic acids and their salts (such as polyaspartic acid, polyglutamic acid, polylysine, polyapple acid, polymethacrylic acid, ammonium polymethacrylate salts, sodium polymethacrylate salts, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly(p - styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, ammonium polyacrylate salts, sodium polyacrylate salts, polyamic acid, ammonium polyamic acid salts, sodium polyamic acid salts, and polyglyoxylate), vinyl polymers (such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrolein), sulfonic acids and their salts (such as ammonium methyl taurate salts, sodium methyl taurate salts, sodium methyl sulfate salts, ammonium ethyl sulfate salts, ammonium butyl sulfate salts, sodium vinyl sulfonate salts, sodium 1 - allyl sulfonate salts, sodium 2 - allyl sulfonate salts, sodium methoxymethyl sulfonate salts, ammonium ethoxymethyl sulfonate salts, sodium 3 - ethoxypropyl sulfonate salts, etc.), and amides (such as propionamide, acrylamide,Examples include methylurea, nicotinamide, succinamide, and sulfanilamide, etc.

[0080] When the substrate to be polished is a glass substrate or the like, any surfactant can be preferably used. However, in the case of a silicon substrate for semiconductor integrated circuits or the like, when the influence of contamination by alkali metals, alkaline earth metals, halides, etc. is to be avoided, it is desirable to use an acid or an ammonium salt-based surfactant.

[0081] When the polishing composition according to the present invention contains a surfactant and / or a hydrophilic compound, its content is preferably 0.001 g or more and 10 g or less, more preferably 0.01 g or more and 5 g or less, and particularly preferably 0.1 g or more and 3 g or less per 1 L of the polishing composition as the total amount.

[0082] The content of the surfactant and / or the hydrophilic compound is preferably 0.001 g or more per 1 L of the polishing composition in order to obtain a sufficient effect, and preferably 10 g or less from the viewpoint of preventing the decrease in the polishing rate.

[0083] Only one kind of surfactant or hydrophilic compound may be used, or two or more kinds may be used, and different kinds can be used in combination.

[0084] Regarding the polishing composition of the present invention, when the substrate to be polished contains a metal, a heterocyclic compound may be contained for the purpose of forming a passive layer or a dissolution inhibition layer on the metal to suppress the erosion of the substrate to be polished. Here, the "heterocyclic compound" is a compound having a heterocycle containing one or more heteroatoms. The heteroatom means an atom other than a carbon atom or a hydrogen atom. The heterocycle means a cyclic compound having at least one heteroatom. The heteroatom means only an atom that forms a constituent part of the ring system of the heterocycle, and does not mean an atom that is located outside the ring system, separated from the ring system by at least one non-conjugated single bond, or is a part of a further substituent of the ring system. Preferred heteroatoms include, but are not limited to, a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom. As examples of the heterocyclic compound, imidazole, benzotriazole, benzothiazole, tetrazole, etc. can be used. More specifically, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4-amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, etc. can be mentioned, but are not limited thereto.

[0085] Regarding the content when a heterocyclic compound is blended in the polishing composition according to the present invention, it is preferably 0.001% by mass or more and 1.0% by mass or less, more preferably 0.001% by mass or more and 0.7% by mass or less, and even more preferably 0.002% by mass or more and 0.4% by mass or less.

[0086] If necessary, such as to enhance the effects of the above additives, an acid or a base can be added to adjust the pH of the polishing composition.

[0087] When adjusting the polishing composition according to the present invention to pH 7 or higher, an alkaline substance is used as the pH adjuster. Desirably, amines such as sodium hydroxide, aqueous ammonia, ammonium carbonate, ethylamine, methylamine, triethylamine, and tetramethylamine are used.

[0088] When adjusting the polishing composition to pH less than 7, an acidic substance is used as the pH adjuster. For example, hydroxy acids such as lactic acid, citric acid, malic acid, tartaric acid, and glyceric acid are used.

[0089] In order to keep the pH value of the polishing composition constant, a pH buffer may be used. As the pH buffer, for example, phosphates and borates such as ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium tetraborate tetrahydrate, or organic acids can be used.

[0090] Regarding the polishing composition according to the present invention, a solvent can be used as necessary. Usually, water is used as the solvent, but alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol can be used as necessary, and other water-soluble organic solvents such as ethers, esters, and ketones can also be used. Further, a mixed solvent composed of water and an organic solvent may be used.

[0091] The concentration of the polishing particles in the polishing composition according to the present invention is preferably in the range of 0.5% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less. When the concentration is less than 0.5% by mass, depending on the type of the substrate or the insulating film, the concentration may be too low and the polishing rate may be slow, resulting in a productivity problem. When the concentration of the polishing particles exceeds 50% by mass, the stability of the abrasive becomes insufficient, the polishing rate and polishing efficiency do not further improve, and a dried product may be generated and adhered in the step of supplying the dispersion for the polishing treatment, which may cause scratches.

Examples

[0092] [Analysis methods used in Examples and Comparative Examples] Preferred embodiments of the present invention will be described below. Unless otherwise specified, the measurement methods of various properties in the examples and comparative examples were carried out by the methods described below.

[0093] [1] Method for measuring average particle diameter by dynamic light scattering method The method for measuring the average particle diameter (D1) of particle-linked silica fine particles by the dynamic light scattering method is as follows. The sample (dispersion containing particle-linked silica fine particles) is diluted with 0.58% aqueous ammonia to adjust the silica concentration to 1% by mass, and measured using a laser particle analyzer (for example, particle size measuring device (1)). [Outline of particle size measuring device (1)] Manufactured by Otsuka Electronics Co., Ltd., model number "Zeta potential / particle size measurement system ELSZ-1000" (measurement principle: dynamic light scattering method, light source wavelength: 665.70 nm, temperature adjustment range: 10 to 90 ° C, cell: 10 mm square plastic cell)

[0094] [2] Method for measuring the number of particle-linked silica fine particles (three-dimensional linked particles) having a three-dimensional structure in a particle-linked silica fine particle dispersion (linked particle dispersion) and method for calculating the number ratio 1. Preparation of measurement sample (1) The particle-linked silica fine particle dispersion was concentrated or diluted with ion-exchanged water to a solid content concentration of 0.05% by mass. (2) After applying ultrasonic waves to the dispersion having a solid content concentration of 0.05% by mass in (1) above, 0.1 g thereof was used as a photographing sample. 2. Method for measuring the number ratio of linked particles and three-dimensional linked particles (1) The sample prepared in 1. above was photographed at 200,000 times using a transmission electron microscope (manufactured by Hitachi, Ltd., ultra-high resolution scanning electron microscope, model number S-5500). (2) In the obtained photograph, at least 200 particles having a shape in which particles are linked were arbitrarily selected (3) For these particles, three-dimensional linked particles were specified and the number thereof was counted. The criteria for determining three-dimensional linked particles are as follows. That is, for specific particle-linked silica fine particles, it is necessary to confirm whether the following requirements 1) to 3) are satisfied. 1) The number of linked silica primary fine particles is 5 or more, forming a chain structure 2) Among the particles constituting the main chain, there is at least one branch (branch (a)) bonded to a particle other than the terminal particle. 3) On the particle, a portion with a darker shade can be confirmed to overlap compared to other primary particles. Particle-linked silica fine particles that satisfy the above requirements 1) to 3) are considered to have a branch (branch (b)) extending in the three-dimensional direction or a terminal (terminal (c)) extending in the three-dimensional direction with respect to branch (a), and are regarded as having a three-dimensional structure, and are defined as three-dimensional linked particles. (4) The percentage of the number of three-dimensional linked particles is the number of three-dimensional linked particles per 200 linked particles expressed as a percentage. (5) The volume percentage of three-dimensional linked particles is determined as follows. Using DLa and DTa, the average particle diameter DLT by image analysis method is obtained. DLT is expressed by the following formula. DLT = (DLa + DTa) / 2 Here, when the DLT (average particle diameter) of three-dimensional linked particles is DLTt, the DLT (average particle diameter) of planar linked particles is DLTp, the volume of three-dimensional linked particles is VLTt, and the volume of planar linked particles is VLTp, VLTt and VLTp are determined as follows, respectively. VLTt = Σ(DLTt / Dp) 3 × (percentage of the number of three-dimensional linked particles), VLTp = Σ(DLTp / Dp) 3 × (percentage of the number of planar linked particles), And from the obtained VLTt and VLTp, the volume percentage (W) of three-dimensional linked particles can be obtained by the following formula. W = VLTt / (VLTp + VLTt) × 100 Here, Dp is the average particle diameter [nm] of single particles.

[0095] [3] Measurement method for the average number of linked particles in three-dimensional linked particles 1. Measurement method for the average number of linked particles in three-dimensional linked particles Prepare an electron micrograph measured in the same manner as [2]. Visually count the number of silica primary particles connected in the three-dimensional connected particles in the micrograph. (3) Perform the above (2) for 50 arbitrarily selected three-dimensional connected particles, and average the number of connected silica primary particles. This average value was defined as the average number of connections of the three-dimensional connected particles. 2. Method for measuring the average particle diameter [F] of silica primary particles in three-dimensional connected particles Prepare an electron micrograph measured in the same manner as [2]. (2) Measure the particle diameters of the silica primary particles in the three-dimensional connected particles in the micrograph, and obtain their average value. (3) Perform the above (2) for 50 arbitrarily selected three-dimensional connected particles, obtain 50 average values, and use that value as the average particle diameter [F]. Note that the measurement of planar connected particles is the same as above.

[0096] [4] Method for measuring the average longest diameter (DLa) in the length direction and the average diameter (DTa) in the thickness direction of particle-connected silica fine particles (three-dimensional connected particles) having a three-dimensional branched structure 1. Preparation of measurement sample and photography using a scanning electron microscope (SEM) The preparation of the measurement sample and photography using SEM were performed according to 1. in the method for measuring the average number of connections of the three-dimensional connected particles in [2] above. 2. Method for measuring the average longest diameter (DLa) in the length direction of three-dimensional connected particles (1) Using the electron micrograph used in [2] above, in the three-dimensional connected particles, among the line segments connecting two points between the outer edges of the particles, the length of the line segment with the longest length is defined as the longest diameter (DL). (2) Perform the above (1) for 50 arbitrarily selected three-dimensional connected particles, and use their average value ([the sum of the respective DLs for 50 three-dimensional connected particles] / 50) as the average longest diameter DLa in the length direction. 3. Method for measuring the average diameter (DTa) in the thickness direction of three-dimensional connected particles (1) In the above [2], using the electron micrographs taken, in the case of the three-dimensional linked particles, among the line segments connecting two points between the particle outer edges, the direction of the line segment with the longest length is defined as the length direction, and the direction orthogonal thereto is defined as the thickness direction. (2) Find two intersection points where the line segment orthogonal to the above DL intersects the particle outer edge, and the line segment with the longest distance between the two intersection points is defined as DT. (3) For 50 randomly selected three-dimensional linked particles, the measurement in the above (2) was performed, and the average value (total of 50 DT values / 50) was defined as the average diameter DTa in the thickness direction. 4. For 50 randomly selected three-dimensional linked particles, the measurement in the above (2) was performed, and the coefficient of variation was obtained for each DT value of the 50 three-dimensional linked particles, and the averaged value was defined as the average coefficient of variation (C.V.).

[0097] [6] Method for measuring the particle size in terms of specific surface area of particulate-connected silica fine particles having a three-dimensional branched structure Measurement of specific surface area and average particle size by the Na titration method 1) After collecting a sample corresponding to 1.5 g as SiO2 in a beaker, transfer it to a thermostatic reaction tank (25 °C), and add pure water to make the liquid volume 90 mL. (The following operations were carried out in the thermostatic reaction tank maintained at 25 °C.) 2) Add 0.1 mol / L hydrochloric acid to adjust the pH to 3.6. 3) Add 30 g of sodium chloride, dilute it to 150 mL with pure water, and stir for 10 minutes. 4) Set the pH electrode, and while stirring, add dropwise 0.1 mol / L aqueous sodium hydroxide solution to adjust the pH to 4.0. 5) Titrate the sample adjusted to pH 4.0 with 0.1 mol / L aqueous sodium hydroxide solution, record the titration volume and pH value in the range of pH 8.7 to 9.3 at four or more points. Let the titration volume of 0.1 mol / L aqueous sodium hydroxide solution be X and the pH value at that time be Y, and make a calibration curve. 6) Obtain the consumption volume V (mL) of 0.1 mol / L aqueous sodium hydroxide solution required from pH 4.0 to 9.0 per 1.5 g of SiO2 from the following formula (2), and obtain the specific surface area SA [m 2 / g] according to the following formula (3). V = (A × f × 100 × 1.5) / (W × C) ··· (2) In the above formula, A: Titration volume (mL) of 0.1 mol / L sodium hydroxide aqueous solution required from pH 4.0 to 9.0 per 1.5 g of SiO2 f: Normality of 0.1 mol / L sodium hydroxide aqueous solution W: Sampling amount (g) C: SiO2 concentration (mass %) of the sample represent respectively. SA = 29.0V - 28 ··· (3) Also, the particle size D2 (nm) in terms of specific surface area is obtained from Equation (4). Particle size D2 (nm) in terms of specific surface area = 6000 / (ρ SiO2 × SA) ··· (4) (Here, ρ SiO2 represents the density of silica particles, 2.2 [g / cm 3 .) Measurement of specific surface area and average particle size by BET method (nitrogen adsorption method) 50 mL of the particle - linked silica sol was adjusted to pH 3.5 with HNO3, 40 mL of 1 - propanol was added, and the sample dried at 110 °C for 16 hours was ground in a mortar and then calcined in a muffle furnace at 500 °C for 1 hour to obtain a measurement sample. Then, using a specific surface area measuring device (manufactured by Yuasa Ionics, model number Multi - sorb 12), the specific surface area was calculated by the BET one - point method from the nitrogen adsorption amount using the nitrogen adsorption method (BET method). Specifically, 0.5 g of the sample was placed in the measurement cell, degassed at 300 °C for 20 minutes in a mixed gas stream of 30 v% nitrogen and 70 v% helium, and then the sample was maintained at liquid nitrogen temperature in the above - mentioned mixed gas stream to allow nitrogen to be adsorbed on the sample in equilibrium. Next, while flowing the above - mentioned mixed gas, the sample temperature was gradually raised to room temperature, and the amount of nitrogen desorbed during that time was detected, and the specific surface area of the particle - linked silica sol was calculated using a calibration curve prepared in advance. Also, the obtained specific surface area (SA) was substituted into the above formula (4) to obtain the particle size d1 in terms of specific surface area.

[0098] [7] Method for measuring the content ratios of Ca, Mg, Al and Fe 1. Preparation of Sample Use 80 g of a particulate-linked silica fine particle dispersion liquid adjusted to a solid content concentration of 20% by mass as a sample. 2. Method for Measuring the Content Ratios of Ca, Mg, Al, and Fe (1) Weigh accurately approximately 1 g of the particulate-linked silica fine particle dispersion liquid into a platinum dish. (2) Add 3 mL of phosphoric acid, 5 mL of nitric acid, and 10 mL of hydrofluoric acid to the above (1), and heat on a sand bath. (3) After drying to solid, add a small amount of water and 50 mL of nitric acid to dissolve, transfer to a 100 mL volumetric flask, and add water to make up to 100 mL. (4) Next, repeat the operation of sampling 10 mL of the solution made up to 100 mL into a 20 mL volumetric flask 5 times to obtain 5 aliquots of 10 mL each. (5) Using this, perform measurement by the standard addition method with an ICP plasma emission spectrometer (manufactured by SII, model number SPS5520). (6) Measure the blank in the same method, subtract the blank value for adjustment, and use the measured values for each element. (7) From the above measured values, determine the ratio of the mass of each element (Ca, Mg, Al, and Fe) contained per unit mass of the silica fine particles contained in the particulate-linked silica fine particle dispersion liquid.

[0099] [8] Method for Measuring COD (Chemical Oxygen Demand) When Dissolving Particulate-Linked Silica Fine Particles The oxygen consumption (COD) by potassium permanganate was measured by the following procedure. First, take an appropriate amount of the sample into a 300 mL Erlenmeyer flask, add water to make up to 100 mL, add 10 mL of sulfuric acid (1 + 2) (sulfuric acid 1: water 2 by volume ratio), add 5 mL of silver nitrate solution (200 g / L), shake well, then add 10 mL of 5 mmol / L potassium permanganate solution, and place the flask in a boiling water bath and heat for 30 minutes. At this time, ensure that the surface of the boiling water bath is always above the sample surface. Next, add 10 mL of sodium oxalate solution (12.5 mmol / L), and while maintaining the temperature at 50 - 60 °C, perform back titration with 5 mmol / L potassium permanganate solution, and take the point at which the color of the solution shows a faint pink color as the end point. Separately, a blank test was conducted using water under the same conditions. The mgO / L of the oxygen consumption by potassium permanganate was calculated by the following formula. COD = (a - b) × f × 1000 / V × 0.2 COD: Oxygen consumption by potassium permanganate (mgO / L) a: Volume of 5 mmol / L potassium permanganate solution required for titration (mL) b: Volume of 5 mmol potassium permanganate solution required for titration in the blank test (mL) f: Factor of 5 mmol / L potassium permanganate solution V: Sample volume (mL) 0.2: Oxygen equivalent amount (mg) of 1 mL of 5 mmol / L potassium permanganate solution

[0100] [9] For particle - linked silica microparticles 29 Measurement of Si - NMR spectrum 29 For the measurement of Si CPMAS NMR spectrum, VNMRS - 600 (14.1T, 1 H resonance frequency: 600 MHz) manufactured by Agilent was used. The measurement sample was ground using a mortar and filled into a 5 - mm solid NMR sample tube to be uniform. Then, it was rotated at 6 kHz at the magic angle (54.7°) with respect to the external magnetic field. At this time, 29 the Si resonance frequency was 119.2 MHz, 1 the H 90° pulse width was 5.0 μs, the contact time was 7 ms, the waiting time after FID was 5 s, and the number of integrations of FID was about 10000 times. The peak of polydimethylsilane at - 34.44 ppm was used as the secondary standard of chemical shift, and the obtained spectrum was approximated with a Gaussian function using Origin for waveform separation. As described above, 29 the Si - NMR spectrum was measured, and from this spectrum, the peak intensities and peak areas of Q2, Q3, and Q4 were read. Then, the ratio of the sum of the peak areas of Q2 and Q3 to the peak area of Q4 [(Q2 + Q3) / Q4)] was calculated.

[0101]

[10] Method for Evaluating Polishing Characteristics of SiO2 Insulating Film (Thickness 1 μm) Substrate and Method for Preparing Abrasive Grain Dispersion for Polishing [Preparation of Abrasive Grain Dispersion for Polishing] For each of the particle-linked silica fine particle dispersion or silica fine particle dispersion obtained in each of the examples and comparative examples, ion-exchanged water was added and diluted, and all were adjusted to a solid content concentration of 1.0 mass%. A nitric acid aqueous solution (concentration 5%) was added to each to adjust the pH to 6.0, and an abrasive grain dispersion for polishing was obtained. [Polishing Test Method] As the substrate to be polished, a SiO2 insulating film (thickness 1 μm) substrate prepared by a thermal oxidation method was prepared. This substrate to be polished was set in a polishing apparatus (manufactured by Nanofactor Co., Ltd., NF300), and a polishing pad (Nitta Haas "IC-1000 / SUBA400 concentric circle type") was used. The abrasive grain dispersion for polishing was supplied at a rate of 200 mL / min for 1 minute at a substrate load of 0.04 MPa and a table rotation speed of 90 rpm for polishing. Then, the weight change of the substrate to be polished before and after polishing was determined to calculate the polishing rate (nm / min). In addition, the smoothness (surface roughness [Ra]) of the surface of the polishing substrate was measured using an atomic force microscope (AFM, manufactured by Hitachi High-Technologies Corporation). Since the smoothness and the surface roughness are generally in a proportional relationship, the surface roughness is described in the table.

[0102] [Average Particle Diameter of Silica Fine Particles Used as Raw Materials] The method for measuring the average particle diameter of silica fine particles in the silica fine particle dispersion used as a raw material for producing the particle-linked silica fine particle dispersion of the present invention is as follows. [Measurement Method] A sample prepared using a silica particle dispersion (solid content concentration: 0.05% by mass) was photographed with a transmission electron microscope (magnification: 200,000 times). Using this photograph, 50 primary particles were arbitrarily selected. When each arbitrarily selected primary particle was projected in the photograph (planar view), for circular ones, the diameter was taken as the particle diameter. For primary particles other than circular ones, when projected in the photograph (planar view), for the distance between the outer edges of the particles, the average value of the longest and the shortest was taken as the particle diameter. For the 50 particles, the particle diameters were summed and divided by the number of particles, and the average value was taken as the average particle diameter of silica.

[0103] [Acidic silicic acid solution] An aqueous sodium silicate solution (SiO2 concentration 5% by mass) was prepared by passing it through a cation exchange resin column to obtain an acidic silicic acid solution (SiO2 concentration 4.6% by mass, pH 2.3, SiO2 / Na2O [molar ratio] = 1200). Hereinafter, in the examples and comparative examples, this acidic silicic acid solution was used.

[0104] <Preparation of particle - linked type silica particle dispersion> [Example 1] 147 g of a silica particle dispersion “Cataloid SI - 30” (average particle diameter 12 nm (image analysis method by SEM), solid content concentration 31% by mass, manufactured by Nisshin Kasei Kogyo Co., Ltd.) was diluted with pure water to a solid content concentration of 1.9% by mass. To this diluted silica particle dispersion, 67 g of an aqueous sodium hydroxide solution (concentration 5.0% by mass) was added as a pH adjuster to adjust the pH to 11.1. Next, 375 g of an aqueous polyethyleneimine solution (concentration 0.3% by mass) with a weight - average molecular weight of 600 was added as an organic additive to this silica particle dispersion with adjusted pH. Subsequently, the silica particle dispersion containing this organic additive was held at 98 °C for 120 minutes. 6,923 g of an acidic silicic acid solution (SiO2 concentration 4.6% by mass) was added over 16 hours. By this operation, particle growth was carried out, and at the same time, the neck portions between primary particles were also grown. A particle - linked type silica particle dispersion (solid content concentration 3.7% by mass) was obtained. The obtained particulate-connected silica fine particle dispersion was confirmed to contain particulate-connected silica fine particles having a three-dimensional branched structure by the above measurement method. The number ratio of the particulate-connected silica fine particles having a three-dimensional branched structure (three-dimensional branched structure) was 24%. The particulate-connected silica fine particle dispersion was concentrated with an ultrafiltration device to adjust the SiO2 concentration to 12%. Further, the particulate-connected silica fine particle dispersion was concentrated with a rotary evaporator to adjust the SiO2 concentration to 40% by mass, and various measurements were performed.

[0105] [Example 2] 124 g of a silica fine particle dispersion “Cataloid SI-50” (average particle diameter 30 nm (image analysis method by SEM), solid content concentration 48% by mass, manufactured by Nichi-Kai Shokubai Co., Ltd.) was diluted with pure water to a solid content concentration of 2.4% by mass. To this diluted silica fine particle dispersion, 1,500 g of an aqueous solution of polyethyleneimine having a weight average molecular weight of 600 (concentration 0.1% by mass) as an organic additive was added. Next, 71 g of an aqueous sodium hydroxide solution (concentration 5.0% by mass) as a pH adjuster was added to the silica fine particle dispersion containing this organic additive to adjust the pH to 12.1. Subsequently, the silica fine particle dispersion with the adjusted pH was held at 98° C. for 30 minutes. Subsequently, 5,518 g of an acidic silicic acid solution (SiO2 concentration 4.6% by mass) was added over 16 hours. By this operation, the particles were grown and the neck portions between the primary particles were also grown. A particulate-connected silica fine particle dispersion (solid content concentration 3.3% by mass) was obtained. The obtained particulate-connected silica fine particle dispersion was confirmed to contain particulate-connected silica fine particles having a three-dimensional branched structure by the above measurement method. The number ratio of the particulate-connected silica fine particles (three-dimensionally connected particles) having a three-dimensional branched structure (three-dimensional branched structure) was 23%. Concentration and various measurements of the obtained particulate-connected silica fine particle dispersion were performed in the same manner as in Example 1.

[0106] [Example 3] 83 g of the silica particle dispersion “Cataloid SI-50” (average particle diameter 30 nm (image analysis method by SEM), solid content concentration 48% by mass, manufactured by Nichi-Kai Shokubai Kasei Co., Ltd.) was diluted with pure water to a solid content concentration of 1.9% by mass. To this diluted silica particle dispersion, 61 g of an aqueous sodium hydroxide solution (concentration 5.0% by mass) was added as a pH adjuster to adjust the pH to 11.7. Next, 360 g of an aqueous polyethyleneimine solution (concentration 0.3% by mass) with a weight average molecular weight of 600 was added as an organic additive to the silica particle dispersion with the adjusted pH. Subsequently, the silica particle dispersion containing this organic additive was held at 98 °C for 120 minutes. Subsequently, 7,610 g of an acidic silicic acid solution (SiO2 concentration 4.6% by mass) was added over 20 hours. By this operation, the particles were grown and, at the same time, the neck portions between the primary particles were also grown. A particle-linked silica particle dispersion (solid content concentration 3.7% by mass) was obtained. The obtained particle-linked silica particle dispersion was confirmed to contain particle-linked silica particles having a three-dimensional branched structure by the above measurement method. The number ratio of the particle-linked silica particles having a three-dimensional branched structure (three-dimensional branched structure) was 23%. Concentration of the obtained particle-linked silica particle dispersion and various measurements were carried out in the same manner as in Example 1.

[0107] [Example 4] 111 g of the silica particle dispersion “Cataloid SI-40” (average particle diameter 20 nm (image analysis method by SEM), solid content concentration 40% by mass, manufactured by Nichi-Kai Shokubai Kasei Co., Ltd.) was diluted with pure water to a solid content concentration of 1.9% by mass. To this diluted silica particle dispersion, 62 g of an aqueous sodium hydroxide solution (concentration 5.0% by mass) was added as a pH adjuster to adjust the pH to 12.2. Next, 375 g of an aqueous polyethyleneimine solution (concentration 0.3% by mass) with a weight average molecular weight of 600 was added as an organic additive to the silica particle dispersion with the adjusted pH. The silica microparticle dispersion containing the organic additive was then held at 98°C for 120 minutes. Then, 6,496 g of acidic silicic acid solution (SiO2 concentration 4.6% by mass) was added over 16 hours. This operation caused the particles to grow, and also caused the necks between the primary particles to grow. A particle-linked silica microparticle dispersion (solid concentration 3.5% by mass) was obtained. It was confirmed by the above-mentioned measurement method that the obtained dispersion of inter-particle-linked silica fine particles contained inter-particle-linked silica fine particles having a three-dimensional branched structure. The proportion of inter-particle-linked silica fine particles having a three-dimensional branched structure was 45%. The resulting particle-linked silica fine particle dispersion was concentrated and various measurements were carried out in the same manner as in Example 1.

[0108] [Comparative Example 1] Various measurements were carried out in the same manner as in Example 1 for a silica fine particle dispersion liquid "CATALOID SI-50" (average particle diameter 30 nm (SEM image analysis method), solid content concentration 48 mass %, manufactured by JGC Catalysts and Chemicals Co., Ltd.).

[0109] [Comparative Example 2] Various measurements were carried out in the same manner as in Example 1 for a silica fine particle dispersion liquid "CATALOID SI-45P" (average particle diameter 50 nm (SEM image analysis method), solid content concentration 40 mass %, manufactured by JGC Catalysts and Chemicals Co., Ltd.).

[0110] [Comparative Example 3] 3,986 g of ion-exchanged water was added to 300 g of fumed silica (AEROSIL50, manufactured by Nippon Aerosil Co., Ltd.), and the mixture was wet-disintegrated and pulverized using high-purity silica beads of φ0.25 mm (manufactured by Daiken Chemical Industry Co., Ltd. and Ashizawa Finetech Co., Ltd. Bead Mill LMZ06). 4,286 g of silica microparticle dispersion with a solid content of 7% by mass was obtained. The obtained silica fine particle dispersion was subjected to various measurements in the same manner as in Example 1.

[0111] [Manufacturing conditions and various measurement results] The production conditions in the examples are shown in Table 1. Furthermore, the results of various measurements in the examples and comparative examples are shown in Table 2.

[0112]

Table 1

[0113]

Table 2

[0114] As is clear from the results shown in Table 2, according to the particulate-connected silica fine particle dispersion liquids obtained in Examples 1 to 4, it was confirmed that they had excellent abrasive properties.

Claims

1. A particulate-linked silica particle dispersion liquid containing particulate-linked silica particles having a structure in which primary silica particles are linked, wherein the silica particles contained in the particulate-linked silica particle dispersion liquid containing particulate-linked silica particles having a structure in which the primary silica particles are linked satisfy the requirements of the following [1], and the particulate-linked silica particles having a three-dimensional branched structure included in the silica particles satisfy the requirements of the following [2], [3], [4], [5], [6], [A] and [B]. A particulate-linked silica particle dispersion liquid. [1] The average particle diameter (D1) measured by the dynamic light scattering method of the silica particles is in the range of 92 nm or more and 177 nm or less. [2] The particulate-linked silica particles having a three-dimensional branched structure have a chain-like structure and at least one branch (a), and have a three-dimensional structure with respect to this structure. [3] The particulate-linked silica particles having a three-dimensional branched structure encapsulate a cationic organic polymer component having a weight average molecular weight in the range of 300 or more and 10,000 or less. [4] 61 nm ≦ DLa ≦ 144 nm DLa: The average value of the longest diameter (DL) in the length direction of the particulate-linked silica particles having a three-dimensional branched structure [5] 34 nm ≦ DTa ≦ 94 nm DTa: The average value of the diameter (DT) in the thickness direction of the particulate-linked silica particles having a three-dimensional branched structure [6] 15% ≦ C.V. ≦ 20% C.V.: The average coefficient of variation of the diameter (DT) in the thickness direction of the particulate-linked silica particles having a three-dimensional branched structure [A] When measuring the COD (chemical oxygen demand) when the particulate-linked silica particles are dissolved, the COD measurement value is such that the measurement value for 1 L of a solution in which 100 g of silica is dissolved is 1000 mg / L or more. [B] It contains 5% by number or more and 50% by number or less of the particulate-linked silica particles having a three-dimensional branched structure.

2. The organic-inorganic composite particle dispersion liquid according to Claim 1, wherein the cationic organic polymer component is at least one selected from the group consisting of poly(diethylaminoethyl methacrylate), poly(dimethyldiallylammonium chloride), and polyalkyleneimine.

3. The particulate-linked silica particle dispersion liquid according to Claim 1 or Claim 2, wherein the three-dimensional structure is at least one of the structures of the following (1) and (2). (1) A branch (b) extending in a three-dimensional direction with respect to the branch (a) (2) A terminal (c) extending in a three-dimensional direction with respect to the branch (a)

4. When the ２９ Si-NMR spectrum of the particle-linked silica fine particles is measured, the ratio [(Q2 + Q3) / Q4] of the total peak area of Q2 and Q3 to the peak area of Q4 is in the range of 1.0 or more and 2.0 or less. The particle-linked silica fine particle dispersion liquid according to any one of claims 1 to 3.

5. The particulate-linked silica fine particles having the three-dimensional branched structure, wherein the average number of linkages of the silica primary fine particles is in the range of 5 or more and 20 or less. The particulate-linked silica fine particle dispersion according to any one of Claims 1 to 4.

6. The particulate-linked silica fine particle dispersion according to any one of Claims 1 to 5, characterized in that the ratios of Ca, Mg, Al, and Fe contained in the silica fine particles are as follows. fine particle dispersion. Ca: 25 ppm or less Mg: 25 ppm or less Al: 150 ppm or less Fe: 50 ppm or less

7. An abrasive grain dispersion containing the particulate-linked silica fine particle dispersion according to any one of Claims 1 to 6.

8. A method for producing the particulate-linked silica fine particle dispersion according to Claim 1, including the following Step 1 and Step 2. Step 1: SiO ２ To a silica particle dispersion with a silica concentration of 1.5 mass% or more and 30 mass% or less, a cationic organic polymer component having a weight average molecular weight in the range of 300 or more and 10,000 or less is added in the following ratio (WA / WS １ ), the pH is adjusted to be in the range of 9.0 or more and 12.0 or less, and then heated to 40°C or more and 98°C or less and held for 0.5 hours or more and 64 hours or less to obtain a particle-linked type silica particle dispersion. 0.015 ≤ WA / WS １ ≤ 0.07 (Here, WS １ is the mass of silica in the silica particle dispersion liquid, and WA is the mass of the cationic organic polymer component.) Step 2: With respect to the particulate-linked silica fine particle dispersion obtained in Step 1, adjust the pH to 10.0 or higher by adding an alkali, hold in the range of 70°C or higher and 98°C or lower, and subsequently add an acidic silicic acid solution continuously or intermittently so as to obtain the following ratio (WF / WS ２ ), and perform a treatment for growing particles 0.01 ≤ WF / WS ２ ≤ 20

9. The method for producing an organic-inorganic composite fine particle dispersion according to Claim 8, wherein the cationic organic polymer component is at least one selected from the group consisting of poly(diethylaminoethyl methacrylate), polydimethyldiallylammonium chloride, and polyalkyleneimine.

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