JP2021059490A - Silica-based particle dispersion and method for producing the same - Google Patents

Abstract

To provide a silica-based particle dispersion containing a silica-based particle group capable of achieving high polishing speed and high surface accuracy for a silica-based substrate, an NiP-plated substrate to be polished, or the like.SOLUTION: A silica-based particle dispersion containing a silica-based particle group comprising deformed silica-based particles and non-deformed silica-based particles, wherein the silica-based particle group satisfies the following [1]-[3]: [1] a weight average particle diameter (D1) is between 60 and 400 nm and a specific surface area equivalent particle diameter (D2) is between 20 and 300 nm; [2] a deformation degree D (D=D1/D3) expressed as the ratio of the weight average particle size (D1) to a projected area equivalent particle size (D3) is in the range of 1.1 to 5.0; and [3] when its volume-based particle size distribution is waveform-separated, it shows a multi-peak distribution in which three or more separation peaks are detected.SELECTED DRAWING: None

Description

The present invention relates to a silica-based particle dispersion liquid and the like. Specifically, a silica-based particle group having a preferable particle size, particle size distribution, irregularity, etc. as an abrasive is included, and in particular, a NiP-plated substrate to be polished and a silica-based substrate are chemically mechanically polished (in particular in magnetic disk manufacturing). The present invention relates to a silica-based particle dispersion liquid suitable as an abrasive grain dispersion liquid for polishing for flattening by chemical mechanical polishing (CMP).

In the manufacturing process of magnetic disks, semiconductors, etc., chemical mechanical polishing (CMP) is applied to flatten substrates such as Si wafers, glass HD, and aluminum HD. In this chemical mechanical polishing, a so-called polishing slurry in which abrasive grains such as silica and ceria are dispersed in water and a chemical component is added to control the polishing performance is used. In particular, it is known that abrasive grains have a great influence on polishing performance, and the performance required for abrasive grains is that a high polishing speed can be obtained and defects such as scratches (streak marks) are found on the polished surface. Defects) do not occur.

As a method of obtaining a high polishing rate, it is common to use abrasive grains having a large particle size. However, if the particle size of the abrasive grains becomes too large, the number of abrasive grains per mass decreases, so that the polishing rate decreases and scratches tend to increase. Therefore, in order to obtain a high polishing rate without increasing scratches, it is known that it is effective to make the abrasive grains non-spherical, that is, to make the abrasive grains irregularly shaped particles (odd particles).

As a method for preparing a group of silica particles containing irregularly shaped silica particles having a particle size suitable for an abrasive material, a method of aggregating silica particles at the time of nucleation using water glass as a raw material, or a method of aggregating silica particles at the time of nucleation, or an irregularly shaped seed particle prepared from this method A method of adding a silicic acid solution to a large particle size to grow a large particle size (Patent Document 1) has been conventionally known.

In addition to Patent Document 1, as a method for preparing a group of silica-based particles having a deformed shape and a relatively large particle size, a step of wet-crushing porous silica gel under alkaline conditions to form a crushed gel containing the deformed silica particles. a. The solution containing the crushed gel is heated by adding a silicic acid solution under alkaline conditions, and the pores of the deformed silica particles are built up and filled by the reaction with silicic acid, and the particles are grown in the deformed shape. A method for producing deformed silica particles (Patent Document 2) is known, which comprises step b and step c for recovering the grown deformed silica particles.

Japanese Patent No. 5127452 JP-A-2017-177576

For irregularly shaped particles, the degree of irregularity (ratio of weight average particle diameter to projected area equivalent particle diameter) also greatly affects the polishing performance. Specifically, particles having a large degree of deformation tend to have a high polishing rate. On the other hand, particles having a small degree of deformation tend to have a low polishing rate because they are spherical or nearly elliptical particles. However, since the deformed particles are non-spherical in shape, they usually tend to be scratched more easily than spherical or substantially spherical particles (non-spherical particles), and especially when the degree of deformity is high. The tendency becomes remarkable.

Further, it is generally known that the particle size and the particle size distribution of the abrasive grains have a great influence on the polishing performance, and the abrasive grains having a large particle size have a high polishing speed, but the surface accuracy (surface) of the polishing substrate. Roughness, waviness, scratches, etc.) tend to worsen. On the other hand, with abrasive grains having a small particle size, the surface of the substrate can be finished smoothly and scratches are unlikely to occur, but the polishing speed becomes slow. This applies not only to spherical particles but also to irregularly shaped particles.
Although the irregularly shaped particles have a wide variety of particle size distributions, particles having a relatively large particle size usually have a high polishing rate. Therefore, when a high polishing rate is required, the average particle size is as large as possible. Variant particles are used. However, in the case of irregularly shaped particles having a relatively large average particle size, the tail of the particle size distribution tends to spread widely toward the large particle size side, so that particles that are coarser than the average particle size are often contained in a small amount. Then, due to such coarse particles, the polished substrate tends to be scratched, and the surface roughness and waviness of the substrate tend to be deteriorated. Therefore, as abrasive grains used for polishing requiring a high polishing rate, a variant having a relatively large average particle size and extremely few coarse particles and excessive large particles (these are collectively referred to as "coarse particles"). Particles are desired.

Further, the particles having a relatively small particle size, regardless of whether they are spherical particles or irregularly shaped particles, tend to have a low polishing rate because the amount of polishing of one abrasive grain is small. Further, in the case of particles having a relatively small particle size, abrasive grains tend to remain on the substrate after polishing (this is called "abrasive grain residue"). This abrasive grain residue tends to be difficult to remove even in the cleaning step after polishing. This tendency is also seen in the deformed particles having a relatively large average particle size, and it seems that the tail of the particle size distribution spreads to the small particle size side even in the deformed particles having a relatively large average particle size. It can be said that the irregularly shaped particles having a uniform distribution are likely to generate abrasive grain residues.
Therefore, in order to realize suitable chemical mechanical polishing that achieves both high polishing speed and high surface accuracy, the abrasive grains contain relatively large irregularly shaped particles, and the number of abrasive grains per mass is large, resulting in reduced polishing performance. Abrasive grains that do not contain as much coarse particles as possible and that contain as little as possible relatively small particles that cause residual abrasive grains are desired.

However, it has been difficult to obtain irregularly shaped silica particles having a specific surface area equivalent particle diameter of 100 nm or more by the method of aggregating silica particles during nucleation using water glass as a raw material. Further, in this method, in the silica particle agglutination step at the time of nucleation, some nuclei particles may cause a runaway reaction to generate coarse agglutinations, and these coarse agglutinations cause scratches. There was a problem of becoming. Further, in a method in which irregular silica particles having a specific surface area equivalent particle diameter of 100 nm or less as obtained by this method are used as seed particles and a silicic acid solution is added to the seed particles to grow a large particle size, the specific surface area equivalent particle size is obtained. When the particles are grown using a silicic acid solution so that the particle size is 100 nm or more, the seed particles grow spherically or substantially spherically. Therefore, the deformed seed particles are grown in a deformed state to obtain relatively large deformed silica particles. It was difficult.

Furthermore, the present inventors investigated a method for obtaining deformed silica particles by pulverizing wet silica as another method for preparing a group of silica particles containing deformed silica particles, and found that the deformed silica particles were obtained. , Wet silica with a gel structure has strong particle strength to control the particle size and particle size distribution by crushing or crushing. Therefore, for example, when controlling by crushing treatment, it takes a relatively long time. Since it is necessary to proceed with the treatment under strong crushing conditions, the degree of deformation of the particles tends to decrease as a result. Further, when the porous silica gel having a low degree of deformation thus obtained was used as the abrasive grains for polishing, only the abrasive grains having a remarkably low polishing rate could be obtained because they were porous. Further, there is also a method of growing particles with silicic acid or the like using the obtained porous silica gel having a low degree of deformation as a seed and reinforcing the surface and internal pores with silica to improve the particle strength. As a result, a sufficient polishing rate could not be obtained because the degree of deformation was further reduced due to particle growth.

Therefore, when the present invention is applied to a polishing application, for example, a silica-based particle group capable of achieving high polishing speed and high surface accuracy with respect to a silica-based substrate, a NiP-plated substrate to be polished, or the like (comparison). Silica-based particles (silica-based particle group including irregular-shaped particles having a specific particle size distribution and required particle strength and degree of deformation) and silica-based particles containing this silica-based particle group. It is an object of the present invention to provide a dispersion liquid and a method for producing the silica-based particle group.

In order to solve the above problems, the present inventor has a relatively small specific surface area as seed particles, instead of a deformed seed particle having a relatively large specific surface area and a relatively small primary particle size. , A method of growing seed particles by adding a silicic acid solution to particles made of highly deformed silica-based gel obtained by crushing a silica-based gel having a relatively large primary particle size under specific conditions was investigated. .. The particles made of the highly deformed silica-based gel are obtained by wet-crushing the silica-based gel under alkaline conditions, and have almost no coarse particles and have a relatively uniform particle size. Furthermore, since the raw material silica-based gel has a relatively small specific surface area and a relatively large primary particle size, the strength of the particles made of the silica-based gel is weak and easy to crush, so that it is derived from the structure of the raw material silica-based gel. The high degree of deformation is maintained.

By using particles made of such a highly deformed silica-based gel as seed particles and growing the seed particles in the coexistence of a silicic acid solution, silicic acid is released from the pores (recesses between the primary particles) between the primary particles of the seed particles. Priority is deposited. Since the primary particle size of the seed particles is relatively large here, the pores between the primary particles can be completely filled with silicic acid. Therefore, it is presumed that the particles could be grown while maintaining a high particle strength and a high degree of deformation.
In addition, since the raw material silica gel particles are made of silica gel having a relatively small specific surface area and a relatively large primary particle size, they are easily crushed, so that the coarse particles are preferentially crushed at the time of crushing. It contains almost no coarse particles. It was found that by using this silica-based particle group as abrasive grains, a polished surface having a relatively high polishing rate, significantly suppressing the occurrence of scratches on the polished surface, and having a small surface roughness and waviness can be obtained. It was.

Based on the above findings, the present inventor has a group of silica-based particles composed of deformed silica-based particles and non-deformed silica-based particles having a particle size, particle size distribution, irregularity and particle strength suitable as an abrasive, and silica containing the same. The present invention, which is a method for efficiently producing a system-based particle dispersion and the silica-based particle group, has been completed.
The present invention is the following (1) to (13).

(1) A silica-based particle dispersion liquid containing a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles.
The silica-based particle group is a silica-based particle dispersion liquid satisfying the following [1] to [3].
[1] The weight average particle size (D ₁ ) is 60 to 400 nm, and the specific surface area equivalent particle size (D ₂ ) is 20 to 300 nm.
_{[2] The degree of deformation D (D = D 1} / D ₃ ) represented by the ratio of the weight average particle diameter (D ₁ ) to the projected area equivalent particle diameter (D ₃ ) is in the range of 1.1 to 5.0. To be in.
[3] When the volume-based particle size distribution is waveform-separated, it becomes a multi-peak distribution in which three or more separation peaks are detected.
(2) The silica-based particle dispersion liquid according to (1) above, wherein the silica-based particle group has a skewness in the range of -20 to 20 in its volume-based particle size distribution.
(3) Of the separation peaks obtained as a result of waveform-separating the volume-based particle size distribution of the silica-based particle group, the volume ratio of the maximum particle component is 75% or less. The silica-based particle dispersion liquid according to any one of 2).
(4) The aspect ratio of the small particle side component is in the range of 1.05 to 5.0 in the number-based particle size distribution obtained by SEM image analysis of the silica-based particle group (1). The silica-based particle dispersion liquid according to any one of (3).
(5) The silica-based particle dispersion liquid according to any one of (1) to (4) above, wherein the variation coefficient of the particle size of the volume-based particle size distribution of the silica-based particle group is 30% or more. ..
(6) Smoothness S (S = S) represented by the ratio of _{the area of a circle (S 2} ) equivalent to the average outer peripheral length by _{the image analysis method to the average area (S 1} ) by the image analysis method in the silica-based particle group. The silica-based particle dispersion according to any one of (1) to (5) above, wherein ₂ / S _{1) is in the range of 1.1 to 5.0.}
(7) In the volume basis particle size distribution of the silica particles, the volume of the total volume (Q ₁₎ 0.7 [mu] m or more for the particle fraction of the _{(Q 2) Q (Q =} Q 2 / Q 1) is 5. The silica-based particle dispersion liquid according to any one of (1) to (6) above, which is characterized by having a content of 0% or less.
(8) A polishing abrasive grain dispersion liquid containing the silica-based particle dispersion liquid according to any one of (1) to (7) above.
(9) A group of silica-based particles composed of deformed silica-based particles and non-deformed silica-based particles.
A group of silica-based particles satisfying the following [1] to [3].
[1] The weight average particle size (D ₁ ) is 60 to 400 nm, and the specific surface area equivalent particle size (D ₂ ) is 20 to 300 nm.
_{[2] The degree of deformation D (D = D 1} / D ₃ ) represented by the ratio of the weight average particle diameter (D ₁ ) to the projected area equivalent particle diameter (D ₃ ) is in the range of 1.1 to 5.0. To be in.
[3] When the volume-based particle size distribution is waveform-separated, it becomes a multi-peak distribution in which three or more separation peaks are detected.

(10) A method for producing a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles, which comprises the following steps a to c.
(Step a) A step of wet-crushing a silica-based gel under alkaline conditions to obtain a solution containing particles composed of a highly deformed silica-based gel.
(Step b) A silicic acid solution is added to a solution containing particles made of the highly deformed silica gel under alkaline conditions to heat the solution, and the pores between the primary particles of the particles made of the highly deformed silica gel are formed in the silicic acid solution. A step of growing particles with a high degree of deformity while filling them by reaction with silicic acid contained in the above to make them into deformed silica-based particles.
(Step c) A step of concentrating and recovering a group of silica-based particles containing the grown irregular silica-based particles.
(11) In the step a, the ^{silica-based gel having a specific surface area of 50 to 600 m 2} / g is made into particles composed of the highly deformed silica-based gel having a weight average particle diameter of 60 to 250 nm.
In the step b, the pores between the primary particles of the particles made of the highly deformed silica gel are filled by the reaction with the silicic acid ^{to reduce the specific surface area of the particles made of the highly deformed silica gel to 136 m 2} / g or less. The method for producing a silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles according to the above (10), which is characterized in that the silica-based particles are grown into the deformed silica-based particles having a weight average particle diameter of 60 to 400 nm.
(12) In the step a, the silica-based gel is wet-crushed under alkalinity of pH 8.0 to 11.5 to prepare a solution containing particles composed of the highly deformed silica-based gel.
_{In the step b, the SiO 2} concentration of the solution containing the particles of the highly deformed silica-based gel is adjusted to 1 to 10% by mass, heated to 60 ° C to 170 ° C, and under alkaline pH of 9 to 12.5. Silicic acid solution is added continuously or intermittently to fill the pores between the primary particles of the particles made of the highly deformed silica-based gel by reaction with silicic acid to reduce the specific surface area of the particles and increase the particles. Grow with a deformed degree,
The variant according to (10) or (11) above, wherein in the step c, the solution containing the grown irregular silica-based particles is concentrated to recover the silica-based particle group containing the deformed silica-based particles. A method for producing a group of silica-based particles composed of silica-based particles and non-amorphous silica-based particles.
(13) in said step b, the addition amount of the silicic acid solution is, SiO ₂ molar該珪acid liquid to SiO ₂ molar concentration of the solution containing the particles consisting of the high profiled silica gel 0.5-20 The method for producing a silica-based particle group consisting of a deformed silica-based particle and a non-deformed silica-based particle according to any one of (10) to (12) above, which is characterized in a range of molar doubling.

The silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles of the present invention has a particle size, a particle size distribution, a degree of deformation, and a particle strength suitable as an abrasive. When the particle dispersion is used as, for example, an abrasive grain dispersion for polishing, or when this abrasive grain dispersion is used as it is as a polishing slurry, the target is a NiP-plated film to be polished and a silica-based substrate. However, it can be polished at high speed, and the abrasive grains do not pierce the base material, and at the same time, it has high surface accuracy (less scratches, less surface roughness (Ra) and waviness (Wa) of the substrate to be polished, etc.). Can be achieved.
Further, the silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles of the present invention has a non-smooth surface and has minute protrusions, and polishing debris, ionic components, and oligomer components generated during polishing. It also has a scavenger effect that adsorbs organic substances. Therefore, reattachment of these components to the polishing substrate can be prevented, and a polishing surface with less residue can be achieved.

Further, in the method for producing a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles of the present invention, a step of adding a silicic acid solution by using particles that have undergone outer shape adjustment of a silica-based gel as seed particles. In, the seed particles can be grown large with a high degree of deformation, and the strength of the particles can be increased. As a result, it is possible to efficiently obtain a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles having a particle size, a particle size distribution, a degree of deformation, and a particle strength suitable as an abrasive.

Explanatory drawing of kurtosis in particle size distribution Explanatory drawing of skewness in particle size distribution

The silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles of the present invention, and the silica-based particle dispersion liquid containing the same will be specifically described. In the present invention, the word "particle group" means a set of a large number of particles.

<Weight average particle size (D ₁ )>
_{The weight average particle diameter (D 1} ) of the silica-based particle group of the present invention is 60 to 400 nm, preferably 80 to 350 nm, and most preferably 100 to 300 nm. When a silica-based particle group having a weight average particle diameter in the range of 60 to 400 nm is used as the abrasive grains, a high polishing rate can be obtained and scratches are less likely to occur. When a silica-based particle group having a weight average particle diameter of less than 60 nm is used as the abrasive grains, it is difficult to obtain the required polishing rate, and smaller particles tend to remain on the polished substrate. Further, when a silica-based particle group having a weight average particle diameter of more than 400 nm is used as the abrasive grains, scratches tend to occur, and even if the weight average particle diameter is made larger than this, the abrasive grains per mass. Since the number is reduced, the polishing speed may not be improved.

Here, in the present invention, the weight average particle size (D ₁ ) means that the silica-based particle dispersion to be measured is diluted with a 0.05 mass% sodium dodecyl sulfate aqueous solution to obtain a solid content concentration of 2 mass%. 0.1 ml was injected into a conventionally known disk centrifugal particle size distribution measuring device (for example, manufactured by CPS Institute) with a syringe, and the condition was 18000 rpm in a density gradient solution of 8% to 24% sucrose. It is an average particle size obtained from the weight-based particle size distribution obtained by measuring in. That is, in the present invention, this weight average particle size means "the average particle size of the weight conversion particle size distribution".

<Specific surface area equivalent particle size (D ₂ )>
_{The specific surface area equivalent particle size (D 2} ) of the silica-based particle group of the present invention is 20 to 300 nm, preferably 25 to 250 nm, more preferably 30 to 200 nm, and most preferably 35 to 150 nm. When a silica-based particle group having a specific surface area equivalent particle diameter (D ₂ ) in the range of 20 to 300 nm is used as the abrasive grains, a high polishing rate can be obtained and scratches are unlikely to occur. When a silica-based particle group having a specific surface area equivalent particle diameter (D ₂ ) of less than 20 nm is used as the abrasive grains, it is difficult to obtain the required polishing rate, and smaller particles tend to remain on the polished substrate. It is in. Further, when a silica-based particle group having a specific surface area equivalent particle diameter (D ₂ ) of more than 300 nm is used as abrasive grains, scratches tend to occur and the surface roughness of the substrate after polishing tends to deteriorate. .. Further, even if the specific surface area-equivalent particle size is made larger than this, the number of abrasive grains per mass decreases, so that the polishing rate tends to decrease.

In the present invention, the specific surface area-equivalent particle size (D ₂ ) means the average surface area-equivalent particle size, and the specific surface area (SA: m ² / g) measured by the BET method and the particle density (D 2). ρ) Using [in the case of silica, ρ = 2.2], _{it is calculated from the formula of D 2} = 6000 / (SA × ρ).
Here, the BET method is the following method.
First, the pH of 50 ml of the silica sol (silica particle dispersion) to be measured was adjusted to 3.5 with nitric acid, 40 ml of 1-propanol was added thereto, and the sample dried at 110 ° C. for 16 hours was pulverized in a mortar. After that, it is fired in a muffle furnace at 500 ° C. for 1 hour to prepare a sample for measurement. Then, using a known specific surface area measuring device (for example, manufactured by Yuasa Ionics, model number Multisorb 12, etc.), the specific surface area is calculated from the amount of nitrogen adsorbed by the BET 1-point method using the nitrogen adsorption method (BET method). In the specific surface area measuring device, 0.5 g of the fired sample is taken in a measuring cell, degassed in a mixed gas stream of 30 vol% nitrogen / 70 vol% helium at 300 ° C. for 20 minutes, and then the sample is subjected to the above mixed gas. The temperature is maintained at the liquid nitrogen temperature in the air stream, and the nitrogen is adsorbed to the sample in equilibrium. Next, the sample temperature is gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that period is detected, and the specific surface area (SA) of the silica fine particles in the sample is calculated from a calibration curve prepared in advance. ..

Further, when the specific surface area of the silica-based particle group is high, sintering proceeds during firing in the BET method. Therefore, when the specific surface area (SA) is 100 m ² / g or more, the specific surface area is determined by the titration method. Find (SA).
Here, the titration method is the following method.
First, _{a sample corresponding to 1.5 g of SiO 2} is collected in a beaker, then transferred to a constant temperature reaction tank (25 ° C.), and pure water is added to bring the liquid volume to 90 ml (the following operation is 25). Perform in a constant temperature reaction vessel kept at ° C). Next, a 0.1 mol / L hydrochloric acid aqueous solution is added here so as to have a pH of 3.6. Further, 30 g of sodium chloride is added, diluted with pure water to 150 ml, and stirred for 10 minutes. Then, the pH electrode is set, and a 0.1 mol / L sodium hydroxide solution is added dropwise with stirring to adjust the pH to 4.0. Further, the sample adjusted to pH 4.0 was titrated with a 0.1 mol / L sodium hydroxide solution, and the titration amount in the range of pH 8.7 to 9.3 and the pH value were recorded at 4 points or more. A titration line is prepared by setting the titration amount of 1 mol / L sodium hydroxide solution to X and the pH value at that time to Y. Then, from the formula of V = (A × f × 100 × 1.5) / (W × C), 0.1 mol / L sodium hydroxide required from pH 4.0 to 9.0 per 1.5 g of _{SiO 2} The consumption amount V (ml) of the solution is determined, and using this, the specific surface area is determined according to the formula of SA = 29.0V-28.
In the above formula, A is a titration amount (ml) of 0.1 mol / L sodium hydroxide solution required for pH 4.0 to 9.0 per 1.5 g _{of SiO 2, and f is 0.1 mol / L.} The titer of the sodium hydroxide solution, C means the SiO ₂ concentration (%) of the sample, and W means the sampling amount (g).

<Degree of deformity>
The degree of deformation is expressed by dividing the above-mentioned weight average particle size (D ₁ ) by the particle size corresponding to the projected area (D _3). The particle size corresponding to the projected area (D ₃ ) is measured and calculated by the following method. First, using a scanning electron microscope (SEM), an arbitrary portion of the surface of silica-based particles is photographed in 15 fields with an area of ^{1.1 × 10 -3} mm ^{2 per field at a magnification of 3000 times.} Then, for all the silica fine particles contained in the individual images taken in each of the visual fields, the projected area of each particle is measured by an image analysis method using an image analysis system, and corresponds to each of the measured areas. The particle size (circle diameter) of the circular particles is calculated, and the number average (arithmetic average diameter) of these particles is defined as the projected area equivalent particle size (D ₃ ).
The silica-based particle group of the present invention has a degree _{of deformation D (D = D 1} / D ₃ ) in the range of 1.1 to 5.0, preferably in the range of 1.1 to 4.0, and 1.1 to 4.0. The range of 3.5 is more preferable. A silica-based particle group having a high degree of deformation means that the average aspect ratio of the particle group (the average value of the "major axis / minor axis ratio of the minimum circumscribing square") is high, and when this average aspect ratio is high, At the time of polishing, it is preferable because it comes into contact with the substrate mainly on the major axis of the particles, the contact area with the substrate becomes high, and the polishing speed becomes high. The polishing speed does not improve, and scratches and waviness tend to occur. Further, when the degree of deformation is less than 1.1, it indicates that the shape of the particles is close to a spherical shape, and polishing is performed using a silica-based particle dispersion liquid containing such a silica-based particle group. If done, the polishing rate tends to decrease.
Here, the aspect ratio means the ratio of the long side to the short side (long side / short side) in the rectangle / square inscribed by the particles, which has the smallest area. Further, the average aspect ratio means a simple average value of the aspect ratios of a certain number of particles or more.

The proportions of the deformed silica-based particles contained in the silica-based particle dispersion liquid containing the silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles according to the present invention are the above-mentioned [1], [2] and [ As long as the requirements of 3] are satisfied, the number of irregular silica-based particles having an aspect ratio of 1.1 or more accounts for 30% or more of the total (the silica-based particle group), although it is not particularly limited. Preferably, more preferably 40% or more is recommended.
The method for measuring the number ratio of the deformed silica-based particles having an aspect ratio of 1.1 or more is as shown in Examples described later.

<Kurtosis>
The kurtosis in the volume-based particle size distribution of the silica-based particle group of the present invention is preferably -20 to 20, more preferably -10 to 10, and most preferably -5 to 3. When a silica-based particle group having a kurtosis in this range is used as the abrasive grains, a higher polishing rate can be obtained, and after polishing, the surface is smoother (the surface roughness (Ra) is small and the waviness of the substrate is small). A substrate having a surface (with small Wa) and few scratches) can be obtained.

Here, the kurtosis is calculated only from the particle size distribution regardless of the shape and size of the particles, and when the kurtosis is close to zero (normal distribution), the particle size distribution is close to the normal distribution. It shows that. The particle size distribution in which the kurtosis is larger than zero indicates that the center of the peak is sharper than the normal distribution and the left and right sides of the tail of the distribution are wider (Fig. 1 (a)). The particle size distribution in which the kurtosis is smaller than zero indicates that the peak is flat and the left and right sides of the hem of the distribution are not widened (FIG. 1 (b)).

In the present invention, the kurtosis in the volume-based particle size distribution of the silica-based particle group may be a negative value. When the kurtosis is negative, it indicates that the peak is flat, the left and right small particle and large particle components of the distribution are few, and the peak is flat and the particle size distribution is relatively uniform. When such a silica-based particle group having a small amount of small particle components and a small amount of large particle components is used as the abrasive grains, it is preferable because the amount of abrasive grains remaining is small and the polishing rate is high.

<Skewness>
The skewness in the volume-based particle size distribution of the silica-based particle group of the present invention is preferably -20 to 20, more preferably -15 to 15, and most preferably -10 to 10. When a silica-based particle group having a skewness in this range is used as the abrasive grains, a higher polishing rate can be obtained, and after polishing, the surface is smoother (the surface roughness (Ra) is small and the waviness of the substrate is small). A substrate having a surface (with small Wa) and few scratches) can be obtained.

Here, the skewness is calculated only from the particle size distribution regardless of the shape and size of the particles like the kurtosis, and when the skewness is close to zero, the particle size distribution is close to the normal distribution. It shows that. The particle size distribution in which the skewness is larger than zero has a peak on the left side (smaller particle size side) of the distribution and has a long tail on the right side (Fig. 2 (a)). )) On the other hand, the particle size distribution in which the skewness is smaller than zero has a peak on the right side of the distribution (the side with the larger particle size), indicating that the distribution has a long tail on the left. (Fig. 2 (b)).

Usually, the skewness in the volume-based particle size distribution of the silica-based particle group obtained by the crushing and crushing methods often takes a positive value, and the skewness is likely to be a normal distribution for the particles obtained by the build-up method. It often takes a value close to zero. When the skewness is positive, the particle size distribution has a peak at a position where the particle size is slightly smaller and a wide tail on the large particle size side. When a silica-based particle group having a particle size distribution having a peak on the small particle size side is used as an abrasive grain, since many components have a small particle size, a smooth surface tends to be easily obtained after polishing. On the other hand, the silica-based particle group having a remarkably large skewness has a particle size distribution in which the hem is greatly widened on the large particle size side, and although it depends on the average particle size, scratches tend to occur easily when used as abrasive grains. ..

In the present invention, the skewness in the volume-based particle size distribution of the silica-based particle group may be a negative value. The silica-based particle group having a negative skewness has a peak at a position where the particle size is large and has a particle size distribution in which the hem is widened on the small particle side, but the particle size distribution is sharp on the large particle side. Therefore (that is, there are few remarkably large particles), scratches are unlikely to occur even when used as abrasive grains. However, in the silica-based particle group having a skewness smaller than -20, the hem on the small particle side becomes too wide and the particle size distribution increases, and the small particle component increases. Therefore, when used as abrasive grains, abrasive grain residue tends to occur. is there.

<Measurement of volume-based particle size distribution and calculation method of kurtosis / skewness>
In the present invention, the volume-based particle size distribution of the silica-based particle group is measured by the centrifugal sedimentation method. For example, a silica-based particle dispersion is diluted with a 0.05 mass% sodium dodecyl sulfate aqueous solution to adjust the solid content concentration to 2 mass%, and a known disc centrifugal particle size distribution measuring device (for example, manufactured by CPS Instrument) or the like is used. ) Can be used to measure the volume-based particle size distribution.
The kurtosis and skewness are calculated from the average value and standard deviation of the volume reference particle size distribution thus obtained by a conventionally known formula. For example, JMP Ver. The kurtosis and skewness can be calculated using 13.2. In rare cases, the frequency of a predetermined particle size may take a negative value in the volume-based particle size distribution, and in such a case, the frequency is calculated as zero.

<Multi-peak distribution>
The volume-based particle size distribution of the silica-based particle group of the present invention is a multi-peak distribution in which three or more separation peaks are detected when waveforms are separated by the following method. In the case of a particle group with a single peak distribution, polishing speed and swell are generated according to the particle size, when the particle size is large, the polishing speed is high but the swell is large, and when the particle size is small, the swell is improved. However, the polishing speed is low. On the other hand, in the case of a particle group having a multi-peak distribution, polishing proceeds while leaving polishing marks corresponding to the particle size of each component, and the sum of these becomes the waviness and the polishing rate. Therefore, at the same time as the large particle component, the distribution in which the small particle component shows a sufficient polishing rate (for example, a trapezoidal distribution containing many small particles and large particles, which becomes multi-peak when waveform separated). ), Both polishing speed and waviness can be achieved.

Waveform separation is performed by analyzing the volume-based particle size distribution obtained by the above-mentioned disk centrifugal particle size distribution measuring device using a peak analyzer of graph creation / data analysis software Origin (manufactured by OriginLab Corporation). Do. First, the baseline is set to 0, the peak type is set to Gaussian, the maximum point of the particle size distribution is selected as the peak position, peak fitting is performed without weighting, and the calculated peak deviates from the following conditions 1 and 2. If there is no deviation, the peak position is shifted to an arbitrary position within the distribution range until the following conditions 1 and 2 are satisfied, and peak fitting is repeated. After that, when the corrected R-squared value is 0.99 or less, a peak is added at an arbitrary position in the distribution range, and peak fitting is repeated until the corrected R-squared value becomes 0.99 or more. The number of separated peaks at this time is defined as the number of peaks.
Condition 1: Each calculated peak does not take a value larger than the original distribution.
Condition 2: Each calculated peak does not take a negative value.
The silica-based particle group having such a volume-based particle size distribution with a multi-peak distribution has a wide distribution from large particles to small particles (the distribution is broad), and has more suitable polishing performance.
Specifically, it is desirable that the volume ratio of the maximum peak separated by waveform is 75% or less of the total volume. This is because when the volume ratio of the maximum peak is 75% or less, the distribution becomes broad, and when the waveforms are separated, the separated peaks tend to have a multi-peak distribution of 3 or more.
When the volume ratio of the maximum peak exceeds 75%, the distribution is substantially close to the single peak distribution, and even if the volume reference particle size distribution is waveform-separated, the separation peak tends to be less than 3. is there.

Further, in the silica-based particle group of the present invention, the volume ratio of the maximum particle component among the separation peaks detected when the volume reference particle size distribution is waveform-separated is preferably 75% or less, preferably 73%. The following is more preferable. When such a silica-based particle group is used as abrasive grains, the surface roughness and waviness of the substrate are further improved during polishing due to the small amount of large particle components. Here, in the present invention, the "maximum particle component" means a particle component contained in the separation peak on the particle side having the largest particle size when the volume-based particle size distribution of the silica-based particle group is waveform-separated. ..

<Aspect ratio>
In the silica-based particle group of the present invention, the aspect ratio of the small particle side component is preferably in the range of 1.05 to 5.0 in the number-based particle size distribution obtained as a result of SEM image analysis, and 1.05. It is more preferably in the range of ~ 3.0, further preferably in the range of 1.05 to 2.0, and most preferably in the range of 1.05 to 1.5. The aspect ratio of the small particle side component in the number-based particle size distribution obtained by SEM image analysis is measured and calculated by the following method. First, the total number of particles in the silica-based particle group is counted using a known scanning electron microscope (SEM) and a known image analysis system. In addition, the area of each particle is calculated, the diameter of a circle having an area equal to the area is obtained, and this is used as the particle size. Then, the obtained particle diameters are arranged in order of size, and particles up to 1/3 of the number of particles counted from the small side are set as the small particle side component, and the aspect ratio (major axis of the minimum circumscribing square) is used for each of the particles of the small particle side component. / Minority ratio) is obtained, and their simple average value is defined as the "aspect ratio of the small particle side component".
The aspect ratio of the small particle side component of the silica-based particle group of the present invention is usually smaller than the average aspect ratio of the silica-based particle group. When the aspect ratio of the small particle side component is less than 1.05, such particles are substantially equivalent to spherical particles, so that the polishing rate is low and the polishing rate of the silica-based particle group tends to be low. However, when a silica-based particle group having an aspect ratio of the small particle-side component of more than 1.05 is used as the abrasive grains, the small-particle-side component also exhibits a high polishing rate, so that the polishing rate of the silica-based particle group is further increased. This can be done, defects are less likely to occur, and high surface accuracy tends to be obtained. In addition, when the aspect ratio of the small particle side component is larger than this range, the average aspect ratio of the entire distribution is also higher, so that the polishing speed is high, but defects are likely to occur, and the surface roughness and waviness tend to deteriorate. is there.

Here, as a method of producing particles having a high aspect ratio in which single particles are bonded, for example, a method of associating particles of several tens of nm by using ionic strength adjustment or a polymer to increase the aspect ratio, or preparation of particles. Occasionally, there is a method in which particles are associated by adjusting the ionic strength or the like at the same time as nucleation, and the generated irregular seed particles are further grown to obtain particles having a high aspect ratio. However, in the case of these methods, particles having a high aspect ratio are generated, and at the same time, particles that do not associate are likely to remain. Therefore, particles having a small particle size tend to be particles having a small aspect ratio and are close to spherical, and are spherical particles. Since the polishing rate is low, the polishing rate of the entire particle group tends to be low. On the other hand, the silica-based particle group containing the deformed silica-based particles of the present invention can obtain a high polishing rate because the small particle side component also contains the deformed particles due to the densification action of the crushing step. ..

<Coefficient of variation (CV value)>
The coefficient of variation of the particle size of the volume-based particle size distribution of the silica-based particle group according to the present invention is preferably 30% or more, and more preferably 50% or more. By setting the coefficient of variation within a predetermined range, the volume-based particle size distribution becomes broad, that is, a silica-based particle group having a wide particle size distribution, and more suitable polishing performance is exhibited. In the present invention, the "coefficient of variation (CV value)" is a value obtained by dividing the standard deviation by the average value as a percentage, and indicates a relative variation.
The CV value of the present invention is determined from the volume-based particle size distribution using a disk centrifugal particle size distribution measuring device (manufactured by CPS Instrument).

<Smoothness S>
In the silica-based particle group of the present invention, the smoothness S (S = S _{2 ) represented by the ratio of the area of a circle (S 2} ) equivalent to the average outer peripheral length by _{the image analysis method to the average area (S 1) by the image analysis method.} / S ₁ ) is preferably in the range of 1.1 to 5.0, and more preferably in the range of 1.3 to 4.0. When the S value is higher than 1.0, it indicates that the surface of the deformed silica-based particles contained in the silica-based particle group is not smooth and has a shape having minute irregularities. This is because the deformed seed particles are an aggregate of primary particles, and the surface of the seed particles also has minute protrusions, and the deformed silica-based particles obtained by growing the seed particles have maintained the fine protrusions. This is because it has a shape. Further, when a silica-based particle group containing irregularly shaped silica-based particles having appropriate fine protrusions on the surface of the deformed silica-based particles is used as the polishing abrasive grains, the polishing pressure is concentrated on the protrusions, so that a high polishing rate can be obtained. When the protrusions on the particle surface are excessive, the surface roughness and waviness of the substrate surface after polishing do not deteriorate, but the abrasive grains tend to wear and the polishing speed tends to decrease.

Here, the measurement and calculation of the _{average area (S 1} ) by the image analysis method and the area of the circle (S ₂ ) equivalent to the average outer peripheral length by the image analysis method in the silica-based particle group will be described.
These are measured and calculated by the following methods. First, using a known scanning electron microscope (SEM), an arbitrary part of the particle surface is photographed in 15 fields with an area of ^{1.1 × 10 -3} mm ^{2 per field at a magnification of 3000 times.} For all the silica fine particles contained in the individual images taken in each of the visual fields, the area and the outer peripheral length of each particle were measured using a known image analysis system, and from the measured areas and the outer peripheral length data. The average area (S ₁ ) (simple average value) and the average outer circumference length (simple average value) are calculated, and from this average outer circumference length, a circle equivalent to the average outer circumference length (a circle having the same circumference as the average outer circumference length). The area of (S ₂ ) is calculated.

<Q ₂ / Q ₁ >
In the volume-based particle size distribution of the silica-based particle group of the present invention, the ratio Q (Q = Q ₂ / Q _{1 ) of the volume (Q 2} ) of particles of 0.7 μm or more to the _{total volume (Q 1} ) is determined by the percentage. The display) is preferably 5.0% or less, and more preferably 4.5% or less. In such a silica-based particle group, since the proportion of coarse particles is small, defects such as scratches are less likely to occur during polishing, and the surface roughness of the polished substrate can be made smaller.

Note that the total volume in the silica-based volume-based particle size distribution of the particles of the present invention (Q _1), the volume ratio of each component of the obtained separation peaks result which was waveform separation, the volume fraction and 0 of the maximum particle component. _{The volume (Q 2} ) of particles of 7 μm or more can also be measured by the method using the above-mentioned disc centrifugal particle size distribution measuring device.

<Abrasive grain dispersion for polishing>
The silica-based particle dispersion liquid (silica-based particle dispersion liquid containing the silica-based particle group of the present invention) in which the silica-based particle group of the present invention is dispersed in a dispersion solvent is an abrasive grain dispersion liquid for polishing (hereinafter, "polishing of the present invention". It can also be preferably used as a "abrasive grain dispersion liquid"). In particular, it can be preferably used for polishing magnetic disks. Further, it can be suitably used as an abrasive grain dispersion for polishing for flattening a semiconductor substrate on which a _{SiO 2 insulating film is formed.} Further, a chemical component can be added to control the polishing performance, and the polishing slurry can be suitably used.

The polishing abrasive grain dispersion liquid of the present invention has effects such as a high polishing speed when polishing a magnetic disk, a semiconductor substrate, etc., less scratches on the polished surface during polishing, and less residual abrasive grains on the substrate. Excellent, and the efficiency of polishing work can be significantly improved.

The abrasive grain dispersion liquid for polishing of the present invention contains water and / or an organic solvent as a dispersion solvent. As the dispersion solvent, it is preferable to use water such as pure water, ultrapure water, or ion-exchanged water. Further, the group consisting of a polishing accelerator, a surfactant, a heterocyclic compound, a pH adjusting agent, a pH buffering agent and a precipitation inhibitor as additives for controlling the polishing performance in the abrasive grain dispersion liquid for polishing of the present invention. By adding one or more selected from the above, it is more preferably used as a polishing slurry.

<Abrasion accelerator>
Although it depends on the type of the material to be polished, it can be used as a polishing slurry by adding a conventionally known polishing accelerator to the abrasive grain dispersion liquid for polishing of the present invention. Examples of such include hydrogen peroxide, peracetic acid, urea peroxide and the like, and mixtures thereof. When such an abrasive composition containing a polishing accelerator such as hydrogen peroxide is used, the polishing rate can be effectively improved when the material to be polished is a metal.

Other examples of polishing accelerators include inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, oxalic acid and hydrofluoric acid, organic acids such as acetic acid, or sodium salts, potassium salts, ammonium salts, amine salts and these of these acids. And the like. In the case of a polishing composition containing these polishing accelerators, when polishing a material to be polished composed of composite components, by accelerating the polishing rate for a specific component of the material to be polished, finally flat polishing is performed. You can get a face.

When the abrasive grain dispersion liquid for polishing of the present invention contains a polishing accelerator, the content thereof is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. ..

<Surfactant and / or hydrophilic compound>
In order to improve the dispersibility and stability of the abrasive grain dispersion liquid for polishing of the present invention, a cationic, anionic, nonionic or amphoteric surfactant or hydrophilic compound can be added. Both the surfactant and the hydrophilic compound have an action of lowering the contact angle with the surface to be polished and an action of promoting uniform polishing. As the surfactant and / or hydrophilic compound, for example, those selected from the following groups can be used.

Anionic surfactants include carboxylates, sulfonates, sulfates, phosphates, and carboxylates include soaps, N-acylamino acids, polyoxyethylene or polyoxypropylene alkyl ether carboxylic acids. Acidates, acylated peptides; as sulfonates, alkyl sulfonates, alkylbenzene and alkyl naphthalene sulfonates, naphthalene sulfonates, sulfosuccinates, α-olefin sulfonates, N-acyl sulfonates; sulfates. As salts, sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkylallyl ether sulfates, alkylamide sulfates; as phosphate ester salts, alkyl phosphates, polyoxyethylene or poly Oxypropylene alkylallyl ether phosphate can be mentioned.

As cationic surfactants, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium chloride salts, benzethonium chloride, pyridinium salts, imidazolinium salts; as amphoteric surfactants, carboxybetaine type, sulfobetaine type, Aminocarboxylates, imidazolinium betaine, lecithin, alkylamine oxides can be mentioned.

Examples of nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type, and ether types include polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, and polyoxyethylene poly. Examples thereof include oxypropylene block polymer and polyoxyethylene polyoxypropylene alkyl ether. Examples of the ether ester type include polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitan ester, polyoxyethylene ether of sorbitol ester, and ester type. Examples of polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester, sucrose ester, and nitrogen-containing type include fatty acid alkanolamide, polyoxyethylene fatty acid amide, and polyoxyethylene alkylamide. In addition, a fluorine-based surfactant and the like can be mentioned.

The surfactant is preferably an anionic surfactant or nonionic surfactant, and examples of the salt include ammonium salt, potassium salt, sodium salt and the like, and ammonium salt and potassium salt are particularly preferable.

Further, as other surfactants, hydrophilic compounds and the like, esters such as glycerin ester, sorbitan ester and alanine ethyl ester; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, alkyl. Polyethylene glycol, alkyl polyethylene glycol alkyl ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, polypropylene glycol alkyl ether, polypropylene glycol alkenyl ether, alkyl polypropylene glycol, alkyl polypropylene glycol alkyl ether , Alkyl Polypropylene Glycol Alkenyl Ether, Ethers such as Alkenyl Polypropylene Glycol; Polysaccharides such as Arginic Acid, Pectinic Acid, Carboxymethyl Cellulose, Cardran and Purulane; Amino Acid Salts such as Glycine Ammonium Salt and Glycin Sodium Salt; Polylysine, polyapple acid, polymethacrylic acid, polyammonium methacrylate salt, polysodium methacrylate salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, amino Polycarboxylic acids such as polyacrylamide, ammonium polyacrylic acid salt, sodium polyacrylic acid salt, polyamic acid, ammonium polyamic acid salt, sodium polyamic acid salt and polyglioxylic acid and salts thereof; Vinyl-based polyma; ammonium methyltaurate salt, sodium methyltaurate salt, methylsodium sulfate salt, ethylammonium sulfate salt, butylammonium sulfate salt, sodium vinylsulfonic acid salt, sodium 1-allylsulfonic acid salt, 2-allylsulfonic acid Sulphonic acids such as sodium salt, sodium methoxymethylsulfonic acid salt, ammonium ethoxymethylsulfonic acid salt, sodium 3-ethoxypropylsulfonic acid salt and salts thereof; propionamide, acrylamide, methylurea, nicotineamide, succinate a. Examples thereof include amides such as amides and sulfanilamides.
Of these surfactants, it is preferably recommended to use sodium polyacrylate or sodium polyacrylate. Among the sodium polyacrylate salts, a sodium polyacrylate salt having a weight average molecular weight in the range of 20,000 to 140,000, which is a carbonyl carbon atom in all carbon atoms contained in the sodium polyacrylate salt. A sodium polyacrylate salt having a ratio (ratio of the number of carbon atoms) directly bonded to is in the range of 50 to 60% is preferable. When the ratio (ratio of the number) of carbon atoms directly bonded to the carbonyl carbon atom is in the range of 50 to 60%, precipitation of the silica-based particles occurs in the silica-based particle dispersion containing the sodium polyacrylate. Even in this case, excellent redispersibility can be exhibited. The sodium polyacrylate salt may be a copolymer of a sodium acrylate salt and an ethylene unit.

When the base material to be applied is a glass substrate or the like, any surfactant can be preferably used, but in the case of a silicon substrate for a semiconductor integrated circuit or the like, alkali metal or alkaline soil can be used. When the influence of contamination by metalloids or halides is disliked, it is desirable to use an acid or an ammonium salt-based surfactant thereof.

When the abrasive grain dispersion liquid of the present invention contains a surfactant and / or a hydrophilic compound, the total content thereof shall be 0.001 to 10 g in 1 L of the abrasive grain dispersion liquid for polishing. It is preferably 0.01 to 5 g, more preferably 0.1 to 3 g, and particularly preferably 0.1 to 3 g.

The content of the surfactant and / or the hydrophilic compound is preferably 0.001 g or more in 1 L of the abrasive grain dispersion for polishing, and 10 g or less from the viewpoint of preventing a decrease in the polishing speed in order to obtain a sufficient effect. Is preferable.

Only one type of surfactant or hydrophilic compound may be used, two or more types may be used, or different types may be used in combination.

<Heterocyclic compound>
The abrasive grain dispersion liquid of the present invention is used for the purpose of suppressing erosion of the base material to be polished by forming a passivation layer or a dissolution suppressing layer on the metal when the base material to be polished contains a metal. Heterocyclic compounds may be contained. Here, the "heterocyclic compound" is a compound having a heterocycle containing one or more heteroatoms. Heteroatom means an atom other than a carbon atom or a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. Heteroatoms refer only to the atoms that form the constituents of the heterocyclic ring system, and may be located outside the ring system, separated from the ring system by at least one unconjugated single bond, or the ring system. It does not mean an atom that is part of a further substituent of. Preferred heteroatoms include, but are not limited to, nitrogen atoms, sulfur atoms, oxygen atoms, selenium atoms, tellurium atoms, phosphorus atoms, silicon atoms, and boron atoms. As an example of the heterocyclic compound, imidazole, benzotriazole, benzothiazole, tetrazole and the like 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-amino1,2,4-triazole, 3,5 −Diamino-1,2,4-triazole and the like can be mentioned, but are not limited thereto.

The content of the heterocyclic compound in the abrasive grain dispersion liquid for polishing of the present invention is preferably 0.001 to 1.0% by mass, preferably 0.001 to 0.7% by mass. Is more preferable, and 0.002 to 0.4% by mass is further preferable.

<pH adjuster>
The pH of the polishing composition can be adjusted by adding an acid or a base and a salt compound thereof, if necessary, in order to enhance the effect of each of the above additives.

When adjusting the polishing abrasive grain dispersion liquid of the present invention to pH 7 or higher, an alkaline pH adjusting agent is used. Desirably, amines such as sodium hydroxide, aqueous ammonia, ammonium carbonate, ethylamine, methylamine, triethylamine, tetramethylamine and the like are used.

When the polishing abrasive grain dispersion liquid of the present invention is adjusted to a pH of less than 7, an acidic pH adjusting agent is used. For example, mineral acids such as hydrochloric acid and nitric acid such as hydroxy acids such as acetic acid, lactic acid, citric acid, malic acid, tartaric acid and glyceric acid are used.

<pH buffer>
A pH buffer may be used to keep the pH value of the abrasive grain dispersion liquid for polishing of the present invention constant. As the pH buffer, for example, phosphates such as ammonium dihydrogen phosphate, diammonium hydrogen phosphate, quaternary ammonium tetrahydrate, and borates or organic acid salts can be used.

<Precipitation inhibitor>
In the abrasive grain dispersion liquid for polishing of the present invention, a settling inhibitor may be added for the purpose of suppressing settling and making it easy to disperse even if it is settled. The precipitation inhibitor is not particularly limited, but is a polycarboxylic acid-based surfactant, anionic polymer surfactant, cationic surfactant, sodium polyacrylate, carboxylic acid-based copolymer sodium salt, and carboxylic acid. Copolymer ammonium salt, ammonium polyacrylate, polyacrylic acid, sulfonic acid copolymer sodium salt, fatty acid salt, α-sulfo fatty acid ester salt, alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate ester, Alkyl sulfate triethanolamine, fatty acid diethanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, alkyltrimethylammonium salt, dialkyldimethylammonium chloride, alkylpyridium chloride, alkylcarboxybetaine, styrene / maleic anhydride copolymer , Formalin conjugate of naphthalene sulfonate, carboxymethyl cellulose, olefin / maleic anhydride copolymer, sodium alginate, polyvinyl alcohol, polyalkylene polyamine, polyacrylamide, polyoxypropylene / polyoxyethylene block, polymer starch, polyethyleneimine, Aminoalkyl acrylate copolymers, polyvinyl imidazoline, satokinsan and the like can be mentioned.
When the sedimentation inhibitor is added to the polishing abrasive grain dispersion liquid of the present invention, the total amount is preferably 0.001 to 10 g in 1 L of the polishing abrasive grain dispersion liquid, and is 0. It is more preferably 0.01 to 5 g, and particularly preferably 0.1 to 3 g. This content is preferably 0.001 g or more in 1 L of the abrasive grain dispersion for polishing, and preferably 10 g or less from the viewpoint of preventing a decrease in polishing speed in order to obtain a sufficient effect.

Further, as the dispersion solvent of the abrasive grain dispersion liquid for polishing of the present invention, alcohols such as methanol, ethanol, isopropanol, n-butanol, methyl isocarbinol and the like; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, etc. Ketones such as isophorone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, 3,4-dihydro-2H-pyran and the like. Ethers; glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether; glycol ether acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate Classes; esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, ethylene carbonate; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as hexane, heptane, isooctane and cyclohexane. Classes; halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane, chlorobenzene; sulfoxides such as dimethylsulfoxide; pyrrolidones such as N-methyl-2-pyrrolidone and N-octyl-2-pyrrolidone. And other organic solvents can be used. These may be mixed with water and used.

The solid content concentration contained in the abrasive grain dispersion for polishing of the present invention is preferably in the range of 0.3 to 50% by mass. If this solid content concentration is too low, the polishing rate may decrease. On the contrary, even if the solid content concentration is too high, the polishing rate is rarely improved further, which may be uneconomical.

<Method for producing a group of silica-based particles composed of irregularly shaped silica-based particles and non-modified silica-based particles>
Next, a method for producing a silica-based particle group composed of the deformed silica-based particles and the non-deformed silica-based particles of the present invention will be specifically described.
This is a step a in which the silica-based gel is wet-crushed under alkaline conditions to form a solution containing particles composed of highly deformed silica-based gels, and a silicic acid solution in a solution containing particles composed of the highly deformed silica-based gels under alkaline conditions. Is added and heated to fill the gaps between the primary particles of the particles made of the highly deformed silica-based gel by the reaction with the silicic acid contained in the silicic acid solution, and the particles are grown with a high degree of deformity to become deformed silica-based particles. This is a method including a step b of performing the process and a step c of concentrating and recovering the silica-based particle group containing the grown irregular silica-based particles.

[Step a]
This step uses a silica-based gel as a starting material. The silica-based gel may be not only silica gel but also a composite gel such as silica-alumina gel, silica-titania gel, and silica-zirconia gel as long as it is a silica-based gel. The gel state may be hydrogel, xerogel, or organogel. Then, such a silica-based gel is wet-crushed under alkaline conditions to obtain a solution containing particles composed of a highly deformed silica-based gel. By pulverizing the silica-based gel and using it as seed particles, the seed particles become silica gel having a high degree of deformation, and the seed particles are hardly spherical and become highly deformed particles. This tendency is remarkable when crushed using a silica-based gel raw material having a small specific surface area and a large primary particle size, and when crushed using a silica-based gel raw material having a large specific surface area and a small primary particle size, the degree of deformation is high. It tends to be low. Furthermore, when crushed so that the seed size becomes smaller, the degree of deformation tends to decrease. Then, in the subsequent step b, the silicic acid solution to be added deposits while invading the silica surface and the inside of the particles (seed particles) made of highly deformed silica-based gel, and reacts preferentially with the pores between the primary particles. While the pores are filled, silica is deposited on the outer surface of the particles to promote the growth of the particles (in the following description, this is referred to as build-up). By this build-up, the convex part of the outer surface of the particle contributes to the increase of the outer diameter, and the concave part contributes less to the outer shape. It is possible to produce deformed silica-based particles having a large diameter and a high degree of deformity.

Further, in the present invention, since a silica-based gel having a small specific surface area and a large primary diameter is used as a manufacturing raw material, its strength is weak. Therefore, even if the silica-based gel is pulverized so that the weight average particle diameter is several hundred nm, fine particles of about several tens of nm are also generated at the same time during pulverization. Therefore, when a silica-based gel is used as a production raw material, the particles obtained by pulverization thereof range from small particles to large particles. Therefore, the silica-based particle group of the present invention has a large weight average particle diameter and also includes fine particles at the same time, resulting in high skewness and kurtosis.

The silica-based gel used as a raw material for production is preferably a gel that is easily crushed. For example, a wet hydrogel obtained by washing a gel of the water glass method, or a dry silica gel, xerogel, or white obtained by drying the hydrogel or the like. Carbon, precipitation silica gel, gel silica, gel by alkoxide method and the like are preferable. Since the gel obtained by the alkoxide method has few hydroxyl groups that undergo dehydration condensation, the dry powder is soft and can be used as a highly productive dry powder. It is preferable that the particle size distribution of the particles composed of the deformed silica-based gel obtained by crushing the silica-based gel is controlled within a certain range, and if it is a large gel mass that is difficult to crush, it takes time to crush. This is not preferable because it tends to increase the particle size distribution.

The silica-based gel used in the present invention preferably has a specific surface area in the range of ^{50 to 600 m 2 / g.} When the specific surface area is ^{smaller than 50 m 2} / g, the pores between the primary particles of the silica-based gel are small. Therefore, when the silicic acid solution is added to the solution containing the particles of the deformed silica-based gel obtained by crushing, The amount of silicic acid that permeates the pores between the primary particles of the irregularly shaped silica-based gel is small, and it becomes difficult for these pores to be filled by the reaction with silicic acid, so that the added silicic acid solution causes the particles to grow round. It is consumed by and tends to be difficult to maintain its irregular shape. Further, if the specific surface area is ^{larger than 600 m 2} / g, the particle strength is too strong and difficult to crush, and long-time crushing is required to reduce coarse particles or to adjust the particle size to a predetermined value. Therefore, the degree of deformation tends to be low.
The size (particle size) of the silica-based gel is preferably in the range of 1 μm to 10 mm.

The silica-based gel is wet-crushed under alkaline conditions to form particles composed of a highly deformed silica-based gel. In particular, ^{a relatively soft silica-based gel having a specific surface area of about 50 to 600 m 2} / g is used in a bead mill or the like. By simultaneously deforming and crushing under a strong shear, particles made of irregularly shaped silica-based gel can be prepared into particles having a high degree of irregularity. For crushing, for example, a sand mill crusher containing a glass medium or a bead mill may be used. Crushing is preferably performed in the shortest possible time.

Normally, when powder is crushed with a bead mill or the like, the particle size of the powder becomes smaller in proportion to the crushing time, but a silica-based gel having a small specific surface area and a large primary diameter requires a short time and weight average particles. The particles are crushed into particles having a diameter of about 60 to 250 nm, and the particles made of this highly deformed silica-based gel have a coarse structure containing a considerable number of necks between the primary particles while maintaining the specific surface area before crushing. ing. Therefore, even if these particles are used as they are as an abrasive, they tend to collapse due to insufficient strength, and only a very low polishing rate can be obtained. Therefore, in the present invention, in the subsequent step b, the silicic acid solution is added to the solution containing the particles made of the highly deformed polyrica gel, and the pores between the primary particles inside the particles made of the deformed silica gel are formed into the silicic acid solution. The strength of the particles is increased by building up and filling with. Here, the silicic acid solution used for build-up may be derived from alkoxide, sodium silicate, or amine silicate. Further, as long as the space between the primary particles can be filled, the content is not limited to silicic acid, and silicates such as an alkaline salt of silicic acid and an alkaline earth salt may be used.

In step a, the silica-based gel is wet-crushed under alkaline conditions, that is, under alkaline conditions, and the alkalinity is preferably in the range of pH 8.0 to 11.5. As the pH drops below the alkaline range, the negative potential gradually drops and becomes unstable in the neutral to acidic range, so that the particles generated by crushing cannot exist stably and tend to agglomerate immediately. Further, when the pH is more than 11.5, the dissolution of silica is promoted, so that it also tends to aggregate. The pH at the time of wet crushing is preferably in the range of 8.5 to 11.0.
The method of adjusting the pH here is not particularly limited. For example, it can be adjusted by adding sodium hydroxide or the like.

The weight average particle size of the particles made of the highly deformed silica-based gel obtained by the wet crushing is preferably in the range of 60 to 250 nm. If the weight average particle size of the particles made of a highly deformed silica-based gel is smaller than 60 nm, it may be difficult to obtain a particle size suitable for the abrasive even if the particles are subsequently grown by adding a silicic acid solution. .. Further, if the weight average particle size of the particles made of the highly deformed silica-based gel is larger than 250 nm, the particle size suitable for the abrasive may be exceeded, which is not very preferable. Coarse particles that exceed the particle size suitable for such abrasives can cause scratches. Coarse particles and large particles tend to be preferentially crushed by crushing, but centrifugation may be performed for the purpose of removing the coarse particles remaining on the highly deformed silica-based gel. The weight average particle size of the particles made of the highly deformed silica-based gel is preferably in the range of 80 to 250 nm.

Here, the weight average particle size of the particles made of the highly deformed silica-based gel means a value obtained by measuring by the same method as the _{weight average particle size (D 1) of the silica-based particle group described above.}

This crushing can be performed in multiple stages using media of different materials and sizes. For example, when a silica-based gel is crushed with a large-sized zirconia medium, the first-stage crushing can be performed at high speed and in a short time due to a strong shearing force. Next, when the second stage of crushing is performed with a glass medium smaller in size than the first stage, the crushing proceeds with a moderate shearing force, and the particle size can be adjusted to a desired value. At this time, since the parts with weak strength between the primary particles are destroyed, the shape tends to be deformed at the same time as the miniaturization. In addition, since the wet crushing is performed under alkaline conditions, some of the particles made of highly deformed silica-based gel are dissolved, and the neck portion between the primary particles can be preferentially filled, so that the crushing is excessively fine. The conversion does not progress.

[Step b]
In this step, a silicic acid solution is added to a solution containing particles made of a highly deformed silica gel under alkaline conditions to heat the solution, and the pores between the primary particles of the particles made of the highly deformed silica gel are reacted with silicic acid. It is a build-up process that grows particles while filling them in a deformed shape. _{The SiO 2} concentration of the solution containing the particles composed of the highly deformed silica-based gel is preferably in the range of 1 to 10% by mass. _{If the SiO 2} concentration of the solution containing the particles composed of the highly deformed silica-based gel is less than 1% by mass, the efficiency of producing the deformed silica-based particles tends to decrease. Further, when the SiO ₂ concentration is more than 10% by mass, fine silica nuclei are generated, the deformability cannot be maintained, and the particle growth of the deformed silica-based particles tends to be non-uniform.
In addition, this step b may be performed by a method of adding a silicic acid solution while hydrothermally treating particles made of a highly deformed silica-based gel. In this method, the added silicic acid solution causes supersaturation, and while some particles are dissolved, silica is deposited and the particles grow. However, the neck portion between the primary particles has a faster deposition rate than the dissolution, so that the primary particles are deposited. The pores between the particles are preferentially filled.

The heating temperature is preferably in the range of 60 ° C. to 170 ° C. This is because if the temperature is lower than 60 ° C., the particles made of the highly deformed silica-based gel tend to grow slowly, and if the temperature is higher than 170 ° C., the obtained deformed silica-based particles tend to be spherical. The heating temperature is more preferably in the range of 60 ° C to 100 ° C.

Further, the pH when the silicic acid solution is added to the solution containing the particles composed of the highly deformed silica-based gel is preferably in the range of 9 to 12.5. When the pH is less than 9, the solubility of silica is low, so that the degree of supersaturation becomes extremely high, and the added silicic acid solution is not consumed for particle growth and is easily generated as fine particles. In addition, since the negative potential is also low, the particles are likely to aggregate. Further, since the dissociation of the hydroxyl group is insufficient, the reactivity with the primary particles is lowered, and the neck portion is not sufficiently reinforced. Further, if the pH is higher than 12.5, the dissolution of silica may be promoted.

The pH of the solution containing the particles of the highly deformed silica-based gel is adjusted as necessary in order to keep the pH in the above range. The adjusting means is not particularly limited, but it is usually adjusted by adding an alkaline substance. Examples of such alkaline substances include sodium hydroxide, water glass and the like. The pH when the silicic acid solution is added to the solution containing the particles of the highly deformed silica-based gel is preferably in the range of 9.5 to 12.0.

The addition amount of the silicic acid solution is in the range of SiO ₂ molar該珪acid liquid to SiO ₂ molar concentration of the solution containing the particles consisting of the high profiled silica gel is 0.5 to 20 times by mole are preferable. This is because if the amount of the silicic acid solution added is less than the above range, the strength between the primary particles cannot be sufficiently increased, so that the strength of the particles tends to decrease. Further, when the particles are grown by adding a silicic acid solution or the like, the degree of deformation and the aspect ratio are usually lowered, but when the amount of the silicic acid solution added is larger than the above range, the degree of deformation of the particles is significantly lowered, which is desired. This is because there is a tendency that the degree of deformation cannot be maintained. Further, since the small particle component grows preferentially as compared with the large particle component during particle growth, if the amount of the silicic acid solution added is larger than the above range, it is difficult to obtain the small particle side component having a desired aspect ratio. It tends to be.
Further, it is desirable to add the silicic acid solution continuously or intermittently.

The silicic acid solution permeates into the inside of the particles through the pores between the primary particles of the particles made of a highly deformed silica-based gel, and deposits on the neck portion of the particles to reduce the specific surface area, thereby increasing the strength of the particles. In this step b, the specific surface area of particles consisting of high profiled silica gel, 136m ² / g or less, it is desirable and more preferably in the range of the specific surface area 9m ² / g~136m ² / g. If the specific surface area of the particles made of the deformed silica-based gel is ^{larger than 136 m 2} / g, the size of the obtained deformed silica-based particles is too small, and the polishing rate tends to be slow.
The specific surface area of the particles made of the deformed silica-based gel is measured by the BET method as described in "Measurement of specific surface area" of the examples described later.

The silicic acid solution dropped from the outside uniformly falls on the surface of the deformed silica gel from the liquid phase and binds to the outer surface of the particles made of the deformed silica gel to grow the outer shape of the particles, so that the deformed shape is maintained. It is possible to obtain irregularly shaped silica-based particles having a large particle size. The particle size of the deformed silica-based particles after the particle growth is preferably in the range of a weight average particle size of 60 to 400 nm.
Here, the weight average particle size of the deformed silica-based particles means a value obtained by measuring by the same method as the _{weight average particle size (D 1) of the silica-based particle group described above.}

[Step c]
This step is a step of concentrating and recovering a group of silica-based particles containing grown irregularly shaped silica-based particles. Specifically, for example, a solution containing grown irregular silica-based particles is cooled to about room temperature to 40 ° C., concentrated using an ultrafiltration membrane or the like, and further concentrated using an evaporator or the like to remain silica-based. The particle group may be collected. Centrifugation may be used to remove even coarser particles. From the viewpoint that coarse agglomerates are unlikely to occur due to drying, the concentration is preferably concentrated by an ultrafiltration membrane.

Hereinafter, examples of the present invention will be shown together with comparative examples. In the examples and comparative examples, the specific surface area of the silica-based particle group was measured, the specific surface area equivalent particle diameter (D ₂ ) was calculated, the weight average particle diameter (D ₁ ) was measured, and the projected area equivalent particle diameter (D _3). ) Measurement / calculation, calculation of skewness / kurtosis in volume reference particle size distribution, waveform separation of volume reference particle size distribution, volume measurement in volume reference particle size distribution, aspect ratio calculation of small particle side component, coefficient of variation Calculation, measurement and calculation of the average area (S ₁ ) and the area of the circle equivalent to the average outer circumference (S ₂ ), measurement and calculation of the average pore size of the core internal pores of the deformed silica particles, The average thickness measurement / calculation of the coated silica layer and the polishing test were performed as follows.

[Measurement of specific surface area]
For Examples 1 to 4 and Comparative Examples 3 to 5, the specific surface area was measured and calculated by the BET method. Specifically, the pH of 50 ml of the silica sol to be measured was adjusted to 3.5 with nitric acid, 40 ml of 1-propanol was added thereto, and the sample was dried at 110 ° C. for 16 hours, pulverized in a mortar, and then in a muffle furnace. It was calcined at 500 ° C. for 1 hour to prepare a sample for measurement. Then, using a specific surface area measuring device (manufactured by Yuasa Ionics, model number Multisorb 12), the specific surface area was calculated from the amount of nitrogen adsorbed by the BET 1-point method using the nitrogen adsorption method (BET method).
In the specific surface area measuring device, 0.5 g of the fired sample is taken in a measuring cell, degassed in a mixed gas stream of 30 v% nitrogen / 70 v% helium at 300 ° C. for 20 minutes, and then the sample is subjected to the above mixed gas. The temperature was maintained at the liquid nitrogen temperature in the air stream, and nitrogen was equilibrium-adsorbed to the sample. Next, the sample temperature was gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that period was detected, and the specific surface area of the silica fine particles in the sample was calculated from a calibration curve prepared in advance.
The specific surface areas of Comparative Examples 1, 2 and 6 in which the silica-based gel was crushed (not built up) were measured and calculated by the titration method. Specifically, after _{collecting a sample corresponding to 1.5 g of SiO 2} in a beaker, the sample is transferred to a constant temperature reaction tank (25 ° C.), and pure water is added to bring the liquid volume to 90 ml (the following operation is 25). It is carried out in a constant temperature reaction vessel maintained at ° C.), and then a 0.1 mol / L hydrochloric acid aqueous solution was added so that the pH became 3.6. Further, 30 g of sodium chloride was added, the mixture was diluted with pure water to 150 ml, and the mixture was stirred for 10 minutes. Then, the pH electrode was set, and a 0.1 mol / L sodium hydroxide solution was added dropwise with stirring to adjust the pH to 4.0. Further, the sample adjusted to pH 4.0 was titrated with a 0.1 mol / L sodium hydroxide solution, and the titration amount in the range of pH 8.7 to 9.3 and the pH value were recorded at 4 points or more. A titration line was prepared with the titration amount of 1 mol / L sodium hydroxide solution being X and the pH value at that time being Y. Then, _{the consumption amount of 0.1 mol / L sodium hydroxide solution required for pH 4.0 to 9.0 per 1.5 g of SiO 2} was determined from a predetermined formula, and using this, the specific surface area was determined according to the predetermined formula. Asked.

[Calculation of specific surface area equivalent particle size (D _2)]
Using the specific surface area (SA) measured by the above method and the particle density (ρ = 2.2), the specific surface area equivalent particle size (D ₂ ) is calculated _{from the formula D 2 = 6000 / (SA × ρ).} did.

[Measurement of weight average particle size (D _1)]
The silica-based particle dispersion was diluted with a 0.05 mass% sodium dodecyl sulfate aqueous solution to give a solid content concentration of 2 mass%, and the mixture was used in a disk centrifugal particle size distribution measuring device (model number: DC24000UHR, manufactured by CPS instruments). _{, 0.1 ml was injected with a syringe, and the weight average particle size (D 1} ) was measured under the condition of 18000 rpm in a density gradient solution of 8 to 24% by mass of sucrose. The crushed silica-based gel (particles composed of highly deformed silica-based gel) was also measured by the same method.

[Measurement / calculation of particle size (D _{3) equivalent to projected area]
The measurement and calculation of the particle size (D 3} ) corresponding to the projected area in the silica-based particle group was performed by an image analysis method. Specifically, first, using a scanning electron microscope (SEM), an arbitrary part on the surface of silica-based particles was photographed in 15 fields with an area of ^{1.1 × 10 -3} mm ^{2 per field at a magnification of 3000 times.} .. Then, for all the silica fine particles contained in the individual images taken in each of the visual fields, the projected area of each particle is measured by an image analysis method using an image analysis system, and corresponds to each of the measured areas. The particle size (circle diameter) of the circular particles was calculated, and the average number of these was taken as the particle size equivalent to the projected area (D ₃ ).

[Calculation of kurtosis / skewness in volume-based particle size distribution]
The volume-based particle size distribution was also measured by the method using the above-mentioned disk centrifugal particle size distribution measuring device. Then, using the obtained volume-based particle size distribution data, JMP Ver. Kurtosis and skewness were calculated using 13.2. When the frequency of the predetermined particle size was a negative value in the volume-based particle size distribution, the frequency was set to zero for calculation.

[Waveform separation of volume-based particle size distribution]
The above-mentioned volume-based particle size distribution measurement data was analyzed using a peak analyzer of the graph creation / data analysis software Origin (manufactured by OriginLab Corporation). First, the baseline is set to 0, the peak type is set to Gaussian, the maximum point of the particle size distribution is selected as the peak position, peak fitting is performed without weighting, and the calculated peak deviates from the following conditions 1 and 2. It was confirmed that there was no deviation, and if it deviated, the peak position was shifted to an arbitrary position within the distribution range until the following conditions 1 and 2 were satisfied, and peak fitting was repeated. After that, when the corrected R-squared value was 0.99 or less, a peak was added at an arbitrary position in the distribution range, and peak fitting was repeated until the corrected R-squared value became 0.99 or more. The number of separated peaks at this time was defined as the number of peaks.
Condition 1: Each calculated peak does not take a value larger than the original distribution.
Condition 2: Each calculated peak does not take a negative value.

[Measurement of volume in volume-based particle size distribution]
Total volume in volume-based particle size distribution of the silica-based particles (Q _1), which waveform volume ratio of each component of the separated results obtained separation peaks, the volume fraction and 0.7μm or more particles of the maximum particle component The volume (Q ₂ ) was measured using the above-mentioned disk centrifugal particle size distribution measuring device.

[Aspect ratio calculation of small particle side components]
The aspect ratio of the small particle side component is equal to the area obtained by counting the total number of particles in the silica-based particle group using a scanning electron microscope (SEM) and an image analysis system, and calculating the area of each particle. Find the diameter of the circle and use it as the particle size. Then, the obtained particle diameters are arranged in order of size, and particles up to 1/3 of the number of particles counted from the smaller side are used as small particle side components, and the average value of the aspect ratio (major axis / minor axis ratio of the minimum circumscribing square) is taken. Was defined as the "aspect ratio of the small particle side component".

[Calculation of coefficient of variation]
The coefficient of variation of the volume ratio of each component of the separation peak obtained as a result of waveform-separating the volume-based particle size distribution of the silica-based particle group and the coefficient of variation of the particle size of the volume-based particle size distribution are the above-mentioned volume-based particle size. Each standard deviation and average value were calculated from the distribution measurement data, and this standard deviation was divided by the average value and expressed as a percentage.

[Measurement / calculation of the area of a circle (S ₂ ) equivalent to the average area (S _{1) and average outer circumference length]}
The measurement of the average area (S ₁ ) and the area of the circle equivalent to the average outer peripheral length (S ₂ ) in the silica-based particle group was performed by an image analysis method. Specifically, first, using a scanning electron microscope (SEM), an arbitrary part on the surface of silica-based particles was photographed in 15 fields with an area of ^{1.1 × 10 -3} mm ^{2 per field at a magnification of 3000 times.} .. Then, the area and the outer peripheral length of all the silica fine particles contained in the individual images taken in each of the visual fields are measured by an image analysis method using an image analysis system, and the measured areas and the outer peripheral lengths are measured. The average area (S ₁ ) and the average outer circumference length (simple average value) are calculated from the data, and from this average outer circumference length, the area of a circle equivalent to the average outer circumference length (a circle having the same circumference as the average outer circumference length) ( S ₂ ) was calculated.

[Measurement / calculation of average pore diameter of core internal pores of irregularly shaped silica particles and average thickness of coated silica layer]
The average pore diameter of the core internal pores of the irregularly shaped silica particles and the average thickness of the coated silica layer were measured and calculated as follows. First, a transmission electron microscope (TEM) was used to observe the deformed silica-based particles at a magnification of 200,000, and the maximum diameter of these particles was set as the major axis, and the point at which the major axis was divided into two equal parts was determined. Two points where a straight line orthogonal to it intersects the outer edge of the particle were obtained, and the distance between these two points was taken as the minor axis. Then, the thicknesses of the coated silica layers on both sides of the major axis and the minor axis were obtained, and these were simply averaged to obtain the average thickness of the coated silica layer of one particle. Similarly, the thickness of the silica layer was determined for any 20 particles, and the simple average of these was taken as the average thickness of the coated silica layer in the deformed silica-based particles.
Further, the pore diameters existing on the major axis and the minor axis were determined, and the average thereof was taken as the average pore diameter of one particle. Similarly, the pore diameters of any 20 particles were determined, and the simple average of these was used as the average pore diameter of the irregularly shaped silica particles.

[Silica gel size measurement method]
The size of the silica-based gel was measured using LA-950 manufactured by HORIBA under the following measurement conditions.
The version of LA-950V2 is 7.02, the algorithm option is standard calculation, the refractive index of solid is 1.450, the refractive index of solvent (pure water) is 1.333, the number of iterations is 15, and the circulation speed of the sample input bus is 5. The stirring speed was set to 2, and the measurement was performed using a measurement sequence in which these were set in advance. Then, the measurement sample was put into the sample inlet of the apparatus as the undiluted solution using a dropper. Here, it was input so that the value of the transmittance (R) was 90%. Then, after the value of the transmittance (R) became stable, ultrasonic waves were irradiated for 5 minutes to measure the particle size.

[Method for measuring the proportion of deformed silica-based particles contained in a silica-based particle dispersion containing a group of silica-based particles composed of deformed silica-based particles and non-deformed silica-based particles]
Arbitrary 100 photographic projections obtained by photographing a silica-based particle dispersion at a magnification of 250,000 times (or 500,000 times) with an electron microscope (manufactured by Hitachi, Ltd., model number "S-5500"). For each particle, the aspect ratio (major axis / minor axis ratio of the minimum circumscribing square) was determined. Here, the particles having an aspect of 1.1 or more are irregular silica-based particles. Then, the ratio of the deformed silica-based particles was determined from the number of particles having an aspect ratio of 1.1 or more and the measured number of particles (100 particles).
The results are shown in Table 1.

[Polishing test]
Substrate to be polished A nickel-plated aluminum substrate for hard disks (nickel-plated substrate manufactured by Toyo Kohan Co., Ltd.) was used as the substrate to be polished. This substrate is a donut-shaped substrate (outer diameter 95 mmφ, inner diameter 25 mmφ, thickness 1.27 mm).
Polishing test 344 g of a 9 mass% silica-based particle dispersion was prepared, 5.65 g of 31 mass% hydrogen peroxide solution was added thereto, and then the pH was adjusted to 1.5 with 10 mass% nitric acid to prepare a polishing slurry. Made.
The above-mentioned substrate to be polished is set in a polishing device (Nanofactor Co., Ltd .: NF300), and a polishing pad (FILWEL Co., Ltd. "Bellatrix NO178") is used to load a substrate of 0.05 MPa, a surface plate rotation speed of 50 rpm, and a head rotation speed. At 50 rpm, 1 μm polishing was performed while supplying the polishing slurry at a rate of 40 g / min.
Polishing speed The polishing speed was calculated from the weight difference of the polishing substrate before and after polishing and the polishing time.
Stability of polishing rate Polishing was repeated 5 times under the above conditions, and the coefficient of variation (CV value) of the polishing rate was calculated.
The polished substrate obtained by the smoothing polishing test of the substrate was subjected to an ultrafine defect / visualization macro device (manufactured by VISION PSYTEC, product name: Micro-Max VMX-3100), and the observation condition was white light of MME-250W. Was adjusted to 10%, and LA-180Me was observed at 0%.
In this observation, if a defect is present on the surface of the substrate due to scratches or the like, white light is diffusely reflected and the defective portion is observed as white. On the other hand, white light is specularly reflected in the portion without defects, and the entire surface is observed as black. The observation was carried out in this way, and the area of defects (the area where the substrate was observed to be white) caused by scratches (linear marks) existing on the surface of the substrate was evaluated according to the following criteria.
Defect area rating less than 3% "very few"
3% or more, less than 20% "less"
20% or more, less than 40% "many"
40% or more "very much"
Measure an arbitrary part that divides the outer edge and inner edge of a swell- polished donut-shaped aluminum substrate into two equal parts, measure the part that divides into two equal parts on the opposite side of the measurement part, and measure the average value of these values to measure the swell. It was set as a value. The measurement conditions are as follows.
Equipment: ZygoNewView7200
Lens: 2.5x Zoom ratio: 1.0
Filter: 50-500 μm
Measurement area: 3.75 mm x 2.81 mm

[Example 1]
<Highly deformed silica-based gel fine particle dispersion (1)>
28 g of silica powder (dried silica gel) ("TOKUSIL 928" manufactured by Oriental silicas corporation [SiO ₂ concentration 88.9 mass%, average particle diameter 14 μm, specific surface area 130 m ² / g]) and 472 g of pure water are placed in a 2 L glass beaker. In addition, a 4.8 mass% aqueous sodium hydroxide solution was added to adjust the pH to 10.0. 1135 g of 0.25 mmφ glass medium is added thereto, and the mixture is crushed by a sand mill crusher until the weight average particle size becomes 135 nm. _{Highly deformed silica-based gel fine particle dispersion having a SiO 2} concentration of 4.0% by mass (1). Got

Preparation of Silica Particles Consisting of Deformed Silica Particles and Non-Atypical Silica Particles _{A solution of a SiO 2} concentration of 2.76% by mass by adding ion-exchanged water to the obtained highly deformed silica gel fine particle dispersion (1). 2716 g was obtained. Next, a 4.8% by mass aqueous sodium hydroxide solution and ion-exchanged water were added to prepare _{a solution having a pH of 10.7 and a SiO 2} concentration of 2.5% by mass. Then, the temperature was raised to 98 ° C. and kept at 98 ° C. for 30 minutes. Next, 5573.1 g of an acidic silicic acid solution of 4.6% by mass was added over 20 hours while maintaining the temperature at 98 ° C., and stirring was continued for 1 hour while further maintaining the temperature at 98 ° C.
_{After cooling this preparation to room temperature, it was concentrated to a SiO 2} concentration of 12% by mass with an ultrafiltration membrane (SIP-1013 manufactured by Asahi Kasei Corporation). Further, the particles were concentrated to 30% by mass with a rotary evaporator to obtain a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles. The weight average particle diameter of the obtained silica-based particle group was 111 nm.

[Example 2]
<Highly deformed silica-based gel fine particle dispersion (2)>
To 1194.7 g of a 0.77 mass% potassium chloride aqueous solution, _{600 g of sodium silicate (SiO 2} concentration 24 mass%) and _{70.3 g of an acidic silicic acid solution having a SiO 2} concentration of 4.5 mass% were added with stirring. Then, the temperature was raised to 98 ° C., and after the temperature was raised, the temperature was maintained at 98 ° C. for 40 minutes. Further, 4792.4 g of an acidic silicic acid solution was added while maintaining 98 ° C., and the temperature was maintained at 98 ° C. for 1 hour even after the addition was completed. Silica gel was obtained by allowing to cool to room temperature. The silica gel powder (dried silica gel) obtained by drying this silica gel overnight at 110 ° C. has an average particle size of 60 μm, a specific surface area of 200 m ² / g, and a SiO ₂ content (concentration) of 90.5% by mass. there were.
28 g of this silica powder and 472 g of pure water were added to a 2 L glass beaker, and a 4.8 mass% aqueous sodium hydroxide solution was added to adjust the pH to 10.0. To this was added 2390g zirconia main Zia of 1.0 mm, subjected to a sand mill grinder performs crushed to a weight average particle diameter is 142 nm, SiO ₂ concentration of 4.0 wt% of high profiled silica gel fine particle dispersion ( 2) was obtained.

Preparation of Silica Particles Consisting of Deformed Silica Particles and Non-Atypical Silica Particles _{A solution of a SiO 2} concentration of 2.76% by mass by adding ion-exchanged water to the obtained highly deformed silica gel fine particle dispersion (2). 2400 g was obtained. Next, a 4.8% by mass aqueous sodium hydroxide solution and ion-exchanged water were added to prepare _{a solution having a pH of 10.7 and a SiO 2} concentration of 2.5% by mass. Then, the temperature was raised to 98 ° C. and kept at 98 ° C. for 30 minutes. Next, 8208 g of a 4.6% by mass acidic silicic acid solution was added over 20 hours while maintaining the temperature at 98 ° C., and stirring was continued for 1 hour while further maintaining the temperature at 98 ° C.
_{After cooling this preparation to room temperature, it was concentrated to a SiO 2} concentration of 12% by mass with an ultrafiltration membrane (SIP-1013 manufactured by Asahi Kasei Corporation). Further, the particles were concentrated to 30% by mass with a rotary evaporator to obtain a silica-based particle group composed of deformed silica-based particles and non-deformed silica-based particles. The weight average particle diameter of the obtained silica-based particle group was 230 nm.

[Example 3]
<Highly deformed silica-based gel fine particle dispersion (3)>
A solution containing silica hydrogel by diluting 462.5 g of sodium silicate with water to prepare a _{24% by mass sodium silicate aqueous solution in terms of SiO 2} and then adding 25% by mass of sulfuric acid so that the pH becomes 4.0. Got This silica hydrogel solution is maintained at a temperature of 21 ° C. in a constant temperature bath and allowed to stand for 5.75 hours for aging, and then the content of sodium sulfate with respect to silicon _{as SiO 2 contained in the silica hydrogel.} Was washed with pure water until the content was 0.05% by mass to obtain a purified silica hydrogel. Further, this purified silica hydrogel was dried overnight at 110 ° C. to obtain silica powder (dried silica gel) having a _{SiO 2} content (concentration) of 90.5% by mass, an average particle size of 123 μm, and a specific surface area of 403 m ^{2 / g.} ..
28 g of this silica powder (dried silica gel) and 472 g of pure water were added to a 2 L glass beaker, and a 4.8 mass% sodium hydroxide aqueous solution was added to adjust the pH to 10.0. 2390 g of 1.0 mmφ zirconia media is added thereto, and the mixture is crushed by a sand mill crusher until the weight average particle size becomes 314 nm (first stage crushing), _{and highly deformed silica having a SiO 2} concentration of 4.0% by mass. A system gel fine particle dispersion liquid (3) was obtained.

<Highly deformed silica-based gel fine particle dispersion (4)>
Next, 1135 g of 0.25 mmφ glass media was added to the highly deformed silica-based gel fine particle dispersion (3) and crushed until the weight average particle size became 208 nm (second stage crushing), and the SiO ₂ concentration was 3. 1900 g of a highly deformed silica-based gel fine particle dispersion (4) of 5% by mass was obtained.

Preparation of Silica-based Particle Group Consisting of Deformed Silica-based Particles and Non-Deformed Silica-based Particles The obtained high-deformed silica-based gel fine particle dispersion liquid (4) was subjected to the same steps as in Example 1 to obtain deformed silica-based particles and non-deformed silica particles. A silica-based particle group consisting of particles was prepared. The weight average diameter of the obtained silica-based particle group was 128 nm.

[Example 4]
<Highly deformed silica-based gel fine particle dispersion (5)>
A solution containing silica hydrogel by diluting 462.5 g of sodium silicate with water to prepare a _{24% by mass sodium silicate aqueous solution in terms of SiO 2} and then adding 25% by mass of sulfuric acid so that the pH becomes 4.5. Got This silica hydrogel solution is maintained at a temperature of 21 ° C. in a constant temperature bath and allowed to stand for 5.75 hours for aging, and then the content of sodium sulfate with respect to silicon _{as SiO 2 contained in the silica hydrogel.} Was washed with pure water until the content was 0.05% by mass to obtain a purified silica hydrogel. Further, this purified silica hydrogel was dried at 110 ° C. overnight and crushed in an agate mortar to obtain silica powder (dried silica gel). This silica powder (dried silica gel) had a SiO ₂ content (concentration) of 90.7% by mass, an average particle size of 12 μm, and a specific surface area of 354 m ² / g.
28 g of this silica powder (dried silica gel) and 472 g of pure water were added to a 2 L glass beaker, and a 4.8 mass% sodium hydroxide aqueous solution was added to adjust the pH to 10.0. 1135 g of 0.25 mmφ glass medium was added thereto, and the mixture was crushed by a sand mill crusher until the weight average particle size became 176 nm. Highly deformed silica-based gel fine particle dispersion liquid (5) _{having a SiO 2 concentration of 4.0% by mass.} Got

Preparation of Silica-based Particle Group Consisting of Deformed Silica-based Particles and Non-Deformed Silica-based Particles The obtained high-deformed silica-based gel fine particle dispersion liquid (5) was subjected to the same steps as in Example 1 to obtain deformed silica-based particles and non-deformed silica-based particles. A silica-based particle group consisting of particles was prepared. The weight average diameter of the obtained silica-based particle group was 200 nm.

[Comparative Example 1]
Comparative Example 1 was "Cataloid SI-80P" (manufactured by JGC Catalysts and Chemicals Co., Ltd .: silica concentration 40% by mass), which is a dispersion liquid in which silica fine particles are dispersed.

[Comparative Example 2]
Comparative Example 2 was "SS-160" (manufactured by JGC Catalysts and Chemicals Co., Ltd .: silica concentration 20% by mass), which is a dispersion liquid in which silica fine particles are dispersed.

[Comparative Example 3]
Comparative Example 3 was "SS-300" (manufactured by JGC Catalysts and Chemicals Co., Ltd .: silica concentration 20% by mass), which is a dispersion liquid in which silica fine particles are dispersed.

Tables 1 and 2 show all the analysis results and measurement results in Examples and Comparative Examples.
Specifically, waveform separation of weight average particle size (D ₁ ), specific surface area equivalent particle size (D ₂ ), sharpness, strain, deformity (D = D ₁ / D ₃ ), and volume-based particle size distribution. Number of separation peaks by, volume ratio of maximum particle component among the separation peaks obtained as a result of waveform separation of volume reference particle size distribution, small particle size side component in the number reference particle size distribution obtained by SEM image analysis Aspect ratio, fluctuation coefficient of particle size of volume-based particle size distribution, ratio _{of circle area (S 2} ) equivalent to average outer circumference length by image analysis to average _{area (S 1} ) by image analysis method (S = S ₂ / S ₁ ), in the volume-based particle size distribution, _{the ratio of the volume (Q 2} ) of particles of 0.7 μm or more to the _{total volume (Q 1} ) (Q = Q ₂ / Q ₁ ), and the value of the aspect ratio are 1. The proportions of one or more particles are shown in Table 1.
Table 2 shows the specific surface area of the silica gel used in step a, the weight average particle size of the particles after crushing, and the pH at the time of wet crushing, after reacting the silica gel particles in step b with silicic acid. Specific surface area, weight average particle size after growth of particles made of silica gel, SiO ₂ concentration of solution containing particles made of silica gel, temperature after heating of solution containing particles made of silica gel, solution containing particles made of silica gel Table 2 shows _{the SiO 2} mol concentration of the silicic acid solution to be added with respect _{to the pH and the SiO 2} mol concentration of the solution containing particles composed of irregular silica gel.
Further, Table 2 shows the measurement results of the polishing rate and the swell.

Since the silica-based particle group of the present invention has suitable particle size, particle size distribution, deformability, and particle strength, the silica-based particle dispersion liquid containing the silica-based particle group can be a NiP-plated substrate to be polished or a silica-based particle. It can be preferably used for surface polishing of substrates and the like.

Claims (13)

A silica-based particle dispersion containing a group of silica-based particles composed of irregularly shaped silica-based particles and non-modified silica-based particles.
The silica-based particle group is a silica-based particle dispersion liquid satisfying the following [1] to [3].
[1] The weight average particle size (D ₁ ) is 60 to 400 nm, and the specific surface area equivalent particle size (D ₂ ) is 20 to 300 nm.
_{[2] The degree of deformation D (D = D 1} / D ₃ ) represented by the ratio of the weight average particle diameter (D ₁ ) to the projected area equivalent particle diameter (D ₃ ) is in the range of 1.1 to 5.0. To be in.
[3] When the volume-based particle size distribution is waveform-separated, it becomes a multi-peak distribution in which three or more separation peaks are detected. The silica-based particle dispersion liquid according to claim 1, wherein the silica-based particle group has a skewness in the range of -20 to 20 in its volume-based particle size distribution. According to any one of claims 1 or 2, wherein the volume ratio of the maximum particle component is 75% or less among the separation peaks obtained as a result of waveform-separating the volume-based particle size distribution of the silica-based particle group. The silica-based particle dispersion liquid described. Any of claims 1 to 3 characterized in that the aspect ratio of the small particle side component is in the range of 1.05 to 5.0 in the number-based particle size distribution obtained by SEM image analysis of the silica-based particle group. Silica-based particle dispersion according to Crab. The silica-based particle dispersion liquid according to any one of claims 1 to 4, wherein the variation coefficient of the particle size of the volume-based particle size distribution of the silica-based particle group is 30% or more. Smoothness S (S = S ₂ / S _{) expressed by the ratio of the area of a circle (S 2} ) equivalent to the average outer peripheral length by _{the image analysis method to the average area (S 1} ) by the image analysis method in the silica-based particle group. The silica-based particle dispersion liquid according to any one of claims 1 to 5, wherein _{1) is in the range of 1.1 to 5.0.} In volume-based particle size distribution of the silica particles, the ratio _{Q (Q = Q 2 / Q} 1) of the volume of 0.7μm or more particles to the total volume (Q ₁₎ (Q ₂₎ is 5.0% or less The silica-based particle dispersion liquid according to any one of claims 1 to 6, wherein the silica-based particle dispersion liquid is characterized by the above. An abrasive grain dispersion liquid for polishing containing the silica-based particle dispersion liquid according to any one of claims 1 to 7. A group of silica-based particles composed of irregularly shaped silica-based particles and non-modified silica-based particles.
A group of silica-based particles satisfying the following [1] to [3].
[1] The weight average particle size (D ₁ ) is 60 to 400 nm, and the specific surface area equivalent particle size (D ₂ ) is 20 to 300 nm.
_{[2] The degree of deformation D (D = D 1} / D ₃ ) represented by the ratio of the weight average particle diameter (D ₁ ) to the projected area equivalent particle diameter (D ₃ ) is in the range of 1.1 to 5.0. To be in.
[3] When the volume-based particle size distribution is waveform-separated, it becomes a multi-peak distribution in which three or more separation peaks are detected. A method for producing a group of silica-based particles composed of deformed silica-based particles and non-deformed silica-based particles, which comprises the following steps a to c.
(Step a) A step of wet-crushing a silica-based gel under alkaline conditions to obtain a solution containing particles composed of a highly deformed silica-based gel.
(Step b) A silicic acid solution is added to a solution containing particles made of the highly deformed silica gel under alkaline conditions to heat the solution, and the pores between the primary particles of the particles made of the highly deformed silica gel are formed in the silicic acid solution. A step of growing particles with a high degree of deformity while filling them by reaction with silicic acid contained in the above to make them into deformed silica-based particles.
(Step c) A step of concentrating and recovering a group of silica-based particles containing the grown irregular silica-based particles. In the step a, the silica-based gel having a specific surface area of 50 to 600 m ² / g is made into particles composed of the highly deformed silica-based gel having a weight average particle diameter of 60 to 250 nm.
In the step b, the pores between the primary particles of the particles made of the highly deformed silica gel are filled by the reaction with the silicic acid ^{to reduce the specific surface area of the particles made of the highly deformed silica gel to 136 m 2} / g or less. The method for producing a silica-based particle group consisting of deformed silica-based particles and non-deformed silica-based particles according to claim 10, wherein the silica-based particles are grown into the deformed silica-based particles having a weight average particle diameter of 60 to 400 nm. In the step a, the silica-based gel is wet-crushed under alkalinity of pH 8.0 to 11.5 to obtain a solution containing particles composed of the highly deformed silica-based gel.
_{In the step b, the SiO 2} concentration of the solution containing the particles of the highly deformed silica-based gel is adjusted to 1 to 10% by mass, heated to 60 ° C to 170 ° C, and under alkaline pH of 9 to 12.5. Silicic acid solution is continuously or intermittently added to fill the pores between the primary particles of the particles made of the highly deformed silica-based gel by reaction with silicic acid to reduce the specific surface area of the particles and to deform the particles. Grow as it is
The deformed silica-based particles according to claim 10 or 11, wherein in the step c, the solution containing the grown deformed silica-based particles is concentrated to recover the silica-based particles group containing the deformed silica-based particles. A method for producing a group of silica-based particles composed of non-amorphous silica-based particles. In the step b, the addition amount of the silicic acid solution is in the SiO ₂ molar concentration of 0.5 to 20 times by mole of該珪acid liquid to SiO ₂ molar concentration of the solution containing the particles consisting of the high profiled silica gel The method for producing a silica-based particle group consisting of a deformed silica-based particle and a non-deformed silica-based particle according to any one of claims 10 to 12, wherein the range is as follows.

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