JP5464834B2 - Polishing silica sol, polishing composition, and method for producing polishing silica sol - Google Patents

Description

  The present invention relates to a silica sol suitable as a polishing composition and a method for producing the same, and in particular, a polishing silica sol capable of suppressing the generation of scratches (linear marks) on a surface to be polished, a method for producing the same, and a polishing composition. It is about things.

  In the field of polishing compositions, when manufacturing a circuit with a metal such as copper on a silicon wafer in the manufacture of a substrate with a semiconductor integrated circuit, unevenness or a step is generated. The metal part of the circuit is preferentially removed so as to be eliminated. Further, when an aluminum wiring is formed on a silicon wafer and an oxide film such as silica is provided thereon as an insulating film, irregularities due to the wiring are generated. Therefore, the oxide film is polished and flattened. In the polishing of such a substrate, the surface after polishing is required to be flat with no steps or irregularities, smooth without microscopic scratches, etc., and the polishing rate must be high.

  In addition, semiconductor materials are becoming more highly integrated as electrical and electronic products become smaller and have higher performance. However, if impurities such as Na or K remain in the transistor isolation layer, the performance cannot be demonstrated. May cause malfunctions. In particular, when Na adheres to the polished semiconductor substrate or the oxide film surface, Na is highly diffusive and is captured by defects in the oxide film. There may be a short circuit, and the dielectric constant may decrease. For this reason, since the said malfunction may arise depending on use conditions or when used over a long term, the abrasive | polishing particle | grains which hardly contain impurities, such as Na and K, are calculated | required. Conventionally, silica sol, fumed silica, fumed alumina, or the like is used as the abrasive particles.

  The polishing material used in CMP is usually spherical polishing particles having an average particle diameter of about 200 nm made of metal silica such as silica and alumina, and an oxidant and organic for increasing the polishing rate of wiring / circuit metals. It consists of an additive such as an acid and a solvent such as pure water. However, the surface of the material to be polished has a level difference (unevenness) due to the wiring groove pattern formed on the underlying insulating film. In addition, it is required to polish the coplanar surface while polishing and removing the convex portion to obtain a flat polished surface. However, with conventional spherical abrasive particles, when the portion above the coplanar surface is polished, the circuit metal in the wiring trench at the bottom of the recess is polished to below the coplanar surface (called dishing) There was.)

  When such dishing (overpolishing) occurs, the thickness of the wiring decreases, thereby increasing the tendency for the wiring resistance to increase. In addition, since problems such as a decrease in flatness of the insulating film formed on the insulating film occur, it has been required to suppress dishing. In recent years, abrasives that exhibit excellent effects in terms of improving the polishing rate, suppressing the generation of scratches (linear traces) on the surface to be polished, and suppressing the surface roughness of the surface to be polished (improving surface accuracy) Is required.

In Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-338951), monodispersed colloidal silica and active silicic acid are mixed with SiO ₂ in a weight ratio of 1: 0.03 to 1: 0.3, and pH is 8 to 11
The technology regarding the colloidal silica for abrasive | polishing agents characterized by performing hydrothermal treatment (120-180 degreeC, 0.5-3 hours) on the conditions of this, and its manufacturing method is disclosed. This colloidal silica has a surface state changed by depositing active silicic acid on monodispersed silica particles under high temperature and high pressure, and the obtained monodispersed colloidal silica is used during surface polishing processing for electronic materials such as semiconductor elements. It is described that the polishing characteristics are excellent.

  Patent Document 2 (Japanese Patent Laid-Open No. 2003-109921) discloses a polishing silica particle dispersion in which silica particles having an average particle diameter in the range of 5 to 300 nm are dispersed, and the Na ion content in the silica particles Is disclosed. An invention relating to a silica particle dispersion for polishing is disclosed, wherein the content of ions other than Na ions is in the range of 300 ppm to 2% by weight. In addition, as part of the method for producing the polishing silica particle dispersion, an example is described in which the silica particle dispersion is hydrothermally treated at 150 ° C. for 11 hours in an autoclave.

According to the colloidal silica for abrasives of Patent Document 1 or the silica particle dispersion for polishing of Patent Document 2, a practical level was observed for the polishing rate and the surface roughness of the substrate to be polished. About suppression of the linear trace on a base material, it did not reach a sufficient level.
JP 2002-338951 A JP 2003-109921 A

  An object of the present invention is to provide a polishing silica sol capable of exhibiting excellent polishing characteristics when applied to polishing applications, and a polishing composition containing the same. Specifically, it is an object of the present invention to provide a polishing silica sol and a polishing composition that are excellent in polishing rate and suppression of generation of linear marks on a surface to be polished. Another object of the present invention is to provide a method for producing the polishing silica sol.

  1st invention for solving the said subject is silica fine particle whose average particle diameter converted from the specific surface area measured by a nitrogen adsorption method is 3-100 nm in a solvent in the range of 1-50 mass% of silica concentration. When the mass of all the silica components present in the silica sol is (S1) and the mass of the dissolved silica components dissolved in the solvent is (S2), (S2) / ( S1) A polishing silica sol having a value of [ppm] of 1000 ppm or less.

In a second invention for solving the above-mentioned problem, the average particle diameter measured by the dynamic light scattering method when the silica concentration of the silica sol is 1% by mass is defined as (D ₁ ). When the average particle size is (D ₃₀ ), the concentration dependency coefficient of the average particle size given by (D ₁ ) / (D ₃₀ ) is in the range of 2.0 to 2.8. This is a polishing silica sol.

  A third invention for solving the above-described problems includes the polishing silica sol, (a) a polishing accelerator, (b) a surfactant, (c) a hydrophilic compound, (d) a heterocyclic compound, (e) A polishing composition comprising a pH adjusting agent and (f) at least one selected from the group consisting of pH buffering agents.

  A fourth invention for solving the above problems is a method for producing a polishing silica sol, wherein a silica sol in which silica fine particles are dispersed in a solvent is passed through a filter having a positive zeta potential.

  The polishing silica sol and the polishing composition obtained by the method for producing a polishing silica sol according to the present invention exhibit at least an equivalent polishing rate and more effectively than the conventional equivalent silica sol and polishing composition. Generation | occurrence | production of a linear trace can be suppressed.

Polishing silica sol In the polishing silica sol according to the present invention, silica fine particles having an average particle diameter of 3 to 100 nm converted from a specific surface area measured by a nitrogen adsorption method are dispersed in a solvent in a range of 1 to 50% by mass. When the mass of all the silica components present in the silica sol is (S1) and the mass of the dissolved silica component is (S2), the ratio of (S2) to (S1) [(S2) / (S1)] is 1000 ppm or less.

The dissolved silica component means a silica component other than the silica component present in the solvent as particles in the average particle size range. Specifically, the dissolved silica component is separated when the silica sol is centrifuged for 90 minutes at a centrifugal force of 4500 G using a centrifuge tube with a separation membrane having a separation membrane having a fractional molecular weight of 10,000. This refers to the silica component present in the dispersion medium that has passed through the membrane and moved to the lower part of the centrifuge tube, and it is assumed that the silica oligomer corresponds to this.

  Generally, it is known that coarse particles having a particle size of about 500 to 3000 nm exist in the silica sol, in addition to silica fine particles having a predetermined particle size range. These coarse particles are known to cause the generation of linear marks when silica sol is applied for polishing.

  The inventors of the present invention have found that the dissolved silica component causes the generation of linear traces in addition to the coarse particles, and have completed the present invention. That is, the present invention has an effect that the occurrence of linear marks is remarkably reduced by making the dissolved silica component below a certain concentration.

  Although it is not always clear why the dissolved silica component causes the occurrence of linear traces, the dissolved silica components such as silica oligomers aggregate over time, thereby reducing the uniformity of the silica fine particles, As a result, when this silica sol is applied to a polishing application, it is presumed that it causes a linear mark.

  In the polishing silica sol according to the present invention, the ratio of the mass (S2) of the dissolved silica component to the mass (S1) of all the silica components present in the silica sol is 1000 ppm or less. When the ratio [(S2) / (S1)] of (S2) to (S1) is 1000 ppm or less, the number of linear traces generated when this polishing silica sol is used for the polishing treatment is remarkable. Less. The ratio of (S2) to (S1) [(S2) / (S1)] is more preferably 900 ppm or less, and even more preferably 850 ppm or less. In the polishing silica sol according to the present invention, it is naturally preferable that the content of the coarse particles is smaller.

The average particle diameter converted from the specific surface area measured by the nitrogen adsorption method (BET method) of the silica fine particles is 3 to 100 nm, preferably 5 to 50 nm, and more preferably 5 to 40 nm. When the average particle diameter is smaller than 3 nm, the polishing rate is low, so that it is unsuitable as an abrasive. When it is larger than 100 nm, the polishing rate is high while scratches (linear marks) increase, so that the polishing base is increased. There is a greater tendency to reduce the surface roughness of the material. In addition, you may use the average particle diameter converted from the specific surface area measured by the sodium titration method instead of the said nitrogen adsorption method (BET method). The measurement of the average particle diameter by the sodium titration method can be performed, for example, as follows.
1) A sample corresponding to 1.5 g as SiO ₂ was collected in a beaker, and then a constant temperature reactor (2
5 ° C.) and add pure water to make the volume 90 ml. The following operation is performed in a constant temperature reaction tank maintained at 25 ° C.
2) A 0.1 mol / L hydrochloric acid solution is added so that the pH is 3.6 to 3.7.
3) Add 30 g of sodium chloride, dilute to 150 ml with pure water and stir for 10 minutes.
4) A pH electrode is set, and 0.1 mol / L sodium hydroxide solution is added dropwise with stirring to adjust the pH to 4.0.
5) The sample adjusted to pH 4.0 was titrated with 0.1 mol / L sodium hydroxide solution, and the titer and pH value in the range of pH 8.7 to 9.3 were recorded at 4 points or more. A calibration curve is prepared by setting the titer of 1 mol / L sodium hydroxide solution to X and the pH value at that time to Y.
6) 0.1 required for pH 4.0 to 9.0 per 1.5 g of SiO ₂ from the following formula (2)
The consumption amount V (ml) of the mol / L sodium hydroxide solution is determined, and the specific surface area SA [m ² / g] is determined according to the following [a] or [b].
[A] In the empirical formula (3), the value of SA is obtained, and when the value is in the range of 80 to 350 m ² / g, the value is SA1.
[B] When the SA value by the experimental formula (3) exceeds 350 m ² / g, the experimental formula (
In 4), SA is obtained, and the value is SA. Further, the average particle diameter D (nm) is obtained from the equation (5).

V = (A × f × 100 × 1.5) / (W × C) (2)
SA = 29.0V-28 (3)
SA = 31.8V-28 (4)
D = 6000 / (ρ × SA) (5) (ρ: density of sample, 2.2 was used for silica)
However, the meanings of the symbols in the above formula (2) are as follows.
A: Titration amount of 0.1 mol / L sodium hydroxide solution required for pH 4.0 to 9.0 per 1.5 g of SiO ₂ (ml)
f: Potency of 0.1 mol / L sodium hydroxide solution C: SiO ₂ concentration of sample (%)
W: Sampling amount (g)
The shape of the silica fine particles is not particularly limited as long as the object of the present invention can be polished, and examples thereof include a spherical shape, a spheroid shape, a chain shape, a confetti shape, and an irregular shape.

  The concentration of the silica fine particles in the polishing silica sol according to the present invention is preferably in the range of 1 to 50 mass%, more preferably in the range of 20 to 40 mass%. When the concentration of the silica fine particles is less than 1% by mass, the productivity is low and a concentration step is required for preparing a polishing composition (slurry). When it is larger than 50% by mass, the stability of the particles decreases and the tendency to aggregate increases.

  The solvent is not particularly limited as long as the fine silica fine particles can be dispersed and can be subjected to polishing treatment, and examples thereof include water, soluble organic alcohol, glycol and the like.

In the polishing silica sol according to the present invention, the average particle size measured by the dynamic light scattering method when the silica concentration of the silica sol is 1% by mass is (D ₁ ), and the average particle size is also 30% by mass. When D is (D ₃₀ ), the concentration dependence coefficient of the average particle diameter given by (D ₁ ) / (D ₃₀ ) tends to be in the range of 2.0 to 2.8. In this regard, it can be said that the dissolved silica component directly affects the measurement by the dynamic light scattering method. Silica sol having a concentration dependency coefficient in this range is suitable for polishing applications, and particularly the occurrence of linear marks is suppressed. When a silica sol having a concentration dependency coefficient of less than 2.0 is applied to a polishing application, the generation of linear marks becomes remarkable. The concentration dependence coefficient of a practical silica sol usually does not exceed 2.8. As a suitable range of the concentration dependence coefficient, a range of 2.1 to 2.5 is recommended.

There is no restriction | limiting in particular in the manufacturing method of the said silica sol for polishing, For example, it can manufacture with the manufacturing method of the silica sol for polishing mentioned later.
Manufacturing method of polishing silica sol The manufacturing method of the polishing silica sol of the present invention is prepared by passing a silica sol in which silica fine particles are dispersed in a solvent through a filter having a positive zeta potential.
Silica sol The silica sol comprises silica fine particles dispersed in a solvent such as water and / or an organic solvent. In the method for producing a polishing silica sol of the present invention, a known silica sol can be used as a raw material. There is no problem with the use of commercial products. This silica sol may contain alumina, zirconia, ceria or titania.

Examples of the method for producing the silica sol include, but are not limited to, the following production methods (1) to (4).
(1) A method for producing a silica sol comprising a step of polymerizing silicic acid by heating a silicic acid solution in the presence of an alkali. This production method comprises alkali metal silicate, tertiary ammonium silicate, quaternary ammonium silicate or guanidine. The method includes a step of polymerizing silicic acid by heating a silicic acid solution obtained by dealkalizing a water-soluble silicate selected from silicates in the presence of an alkali. As an example of this production method, an aqueous alkali silicate solution is diluted with water to a silica concentration of 3 to 10% by mass, and then contacted with an H-type strong acidic cation exchange resin for dealkalization, and if necessary, an OH-type strong base. The active silicic acid is prepared by deanion by contacting with anionic anion exchange resin. An example is a method for producing a silica sol having an average particle diameter of 60 nm or less by adding an alkaline substance so that the pH is 8 or more and heating to 50 ° C. or more.
(2) Silica sol production method for growing core particles by adding an acidic silicic acid solution to the core particle dispersion. In this manufacturing method, the core particle dispersion is not particularly limited as long as it functions as a core particle. Conventionally known fine particle dispersions such as silica, alumina, zirconia, ceria, titania, silica-alumina, silica-zirconia, silica-ceria, silica-titania can be used. Among them, the silica sol and the silica composite oxide sol disclosed in Japanese Patent Application Laid-Open Nos. 5-132309 and 7-105522 by the applicant of the present application have a uniform particle size distribution, and for polishing with a uniform particle size distribution. Since silica particles are obtained, it is preferable. Here, it is preferable that an alkali silicate is added to the core particle dispersion before the addition of the acidic silicate solution. When an alkali silicate is added, the concentration of SiO ₂ dissolved in the solvent is increased in advance when the acidic silicic acid solution for particle growth is added next. The pH of the dispersion can be adjusted to approximately 8 to 12, preferably 9.5 to 11.5. As the alkali silicate used here, it is preferable to use a solution in which silica is dissolved in an organic base such as potassium silicate (potassium water glass), silicate alkali other than sodium silicate (sodium water glass), or quaternary amine. Moreover, alkali metal hydroxides other than NaOH, ammonium, and quaternary ammonium hydride can be added as needed. Furthermore, alkali metal hydroxides such as Mg (OH) ₂ , Ca (OH) ₂ , Sr (OH) ₂ and Ba (OH) ₂ can be preferably used. Even if the core particles are not dispersed in advance, the core particles are generated when the silica concentration is increased when an acidic silicic acid solution described later is added to the alkali silicate aqueous solution. Therefore, such a core particle dispersion is also preferably used. be able to. The concentration of the core particle dispersion varies depending on the size of the core particles, but it is preferably in the range of 0.005 to 20% by mass, more preferably 0.01 to 10% by mass as SiO ₂ .

When the concentration of the core particles is less than 0.005% by mass, some or all of the core particles may be dissolved when the temperature is increased to perform particle growth. When all the core particles are dissolved, the core particles are dispersed. If the effect of using the liquid is not obtained, and part of the core particles is dissolved, the particle diameter of the silica particles obtained tends to be non-uniform, and the effect of using the core particle dispersion may not be obtained as well. is there. On the other hand, if the concentration of the core particles exceeds 20% by mass, the addition rate of the acid silicate solution per core particle should be increased to increase the rate of addition of the silicate solution in order to make the addition rate of the acid silicate solution low. Precipitation of the acidic silicic acid solution on the surface of the core particles cannot follow, and the acidic silicic acid solution may gel. The average particle diameter of the core particles is not particularly limited as long as the silica particles described above can be obtained.
(3) A method for producing a silica sol comprising a step of peptizing a silica hydrogel. This production method comprises washing a silica hydrogel obtained by neutralizing a silicate with an acid, removing salts, and adding an alkali. It includes a step of peptizing the silica hydrogel by heating.

This production method is called a peptization method. Usually, an aqueous solution of silicate is neutralized with an acid to prepare a silica hydrogel, and the silica hydrogel is slurried or mechanically prepared by chemical means or mechanical means. This method is known as a dispersion solution. Here, as a chemical means, the method of adding an alkali to a silica hydrogel and heating as desired is mentioned. Moreover, as a mechanical means, the method of using apparatuses, such as a stirrer, can be mentioned. These chemical means and mechanical means may be used in combination. Specifically, silica hydrogel obtained by neutralizing silicate with acid is washed, salts are removed, alkali is added, and the silica hydrogel is peptized by heating in the range of 60 to 200 ° C. Then, a silica sol is prepared. The silicate used as a raw material in this production method is preferably one or more silicates selected from alkali metal silicates, ammonium silicates, and organic base silicates. Examples of the alkali metal silicate include sodium silicate (water glass) and potassium silicate, and examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, amines such as monoethanolamine, diethanolamine, and triethanolamine. The ammonium silicate or organic base silicate includes an alkaline solution in which ammonia, quaternary ammonium hydroxide, an amine compound, or the like is added to the silicic acid solution.
(4) Manufacturing method comprising hydrolyzing a hydrolyzable silicon compound and polymerizing the resulting silicic acid This manufacturing method hydrolyzes a silicon compound having a hydrolyzable group and polymerizes the resulting silicic acid. It includes a process. As an example of this production method, tetraethoxysilane is added to a water-organic solvent dispersion in which seed particles are dispersed to hydrolyze the tetraethoxysilane, and silica is deposited on the seed particles. For example, a method for producing monodispersed silica particles by performing particle growth is known.

The silica sol prepared by any one of the production methods (1) to (4) can be applied as a raw material (silica sol) to the method for producing a polishing silica sol according to the present invention.
About the silica concentration of the silica sol used as a raw material in the method for producing a polishing silica sol according to the present invention, one having a range of 1 to 50% by mass is usually used. As for the silica fine particles, silica fine particles having an average particle diameter in the range of 1 to 100 nm converted from the specific surface area measured by the nitrogen adsorption method [BET method] (or sodium titration method) are preferably used. Although it is possible to prepare silica fine particles having an average particle diameter of less than 1 nm, it is not practical in terms of cost. For polishing applications, an average particle size of 100 nm or less is practical. Filters having a positive zeta potential When the polishing silica sol composed of a silica sol that has passed through a filter having a positive zeta potential is applied to a polishing application, the inventors prepared through a conventional centrifugal separation process or ultrafiltration. The present inventors have found that the generation of linear marks is more effectively suppressed while ensuring at least the same polishing rate as compared with the silica sol thus obtained, and completed the present invention.

  As described above, the coarse particles, dissolved silica components, and the like can be cited as the causative substances for generating linear traces. Of these causative substances, coarse particles can be removed by a conventional centrifugal separation process or ultrafiltration. However, it has been difficult to remove the dissolved silica component by a conventional centrifugal separation process or the like because the mass or the outer diameter is extremely small.

On the other hand, according to the production method of the present invention in which silica sol is passed through a filter having a positive zeta potential, not only the coarse particles but also dissolved silica components are easily and efficiently removed. This is presumably due to the fact that coarse particles are separated by a normal filtration action, and the dissolved silica component having a relatively large negative zeta potential is adsorbed by the filter having a positive zeta potential. As a result, when a silica sol obtained by passing a silica sol through a filter having a positive zeta potential or a polishing composition containing the same is applied to a polishing application, a silica sol that has only been subjected to a centrifugal separation process or the like is obtained. Compared to the case of applying to polishing, it is easy to suppress the occurrence of linear marks.

  The zeta potential of the filter is measured as follows. The filter membrane is cut into a 15 mm × 35 mm rectangle, and is placed in close contact with the measurement cell and installed in a zeta potential / particle size measurement system (ELSZ-1 manufactured by Otsuka Electronics Co., Ltd.) and a flat sample cell unit. In this device, the monitor particles (polystyrene latex particles whose zeta potential is made substantially zero) to be electrophoresed are injected into the cell, and the monitor particles are electrophoresed at each level in the cell depth direction. The internal apparent velocity distribution is analyzed using the Mori-Okamoto equation to determine the zeta potential on the sample surface.

  The magnitude of the positive zeta potential of the filter is not particularly limited as long as the dissolved silica component can be adsorbed, but is preferably +3 to +60 mV, and more preferably +5 to +50 mV. When the zeta potential of the filter is within the above range, the dissolved silica component is easily adsorbed efficiently. A filter having a positive zeta potential can be said to have a positive charge.

  A filter having such a positive zeta potential is, for example, by treating a filter medium obtained by grafting acrylate onto polyurethane having a negative surface zeta potential with a cationizing agent, thereby making the surface zeta potential positive, Filters with a positive zeta potential can be manufactured. The cationizing agent is not particularly limited as long as it is a substance having a cationic charge in a neutral solution. For example, polyaluminum chloride, a basic substance having an amino group, and the like are preferable. Specific examples of the basic substance having an amino group include quaternary ammonium hydroxide, tertiary amine compound, secondary amine compound and the like. As a specific manufacturing method, for example, it is manufactured by filling a capsule filter with an aqueous solution in which polyaluminum chloride is dissolved in pure water, passing the solution through pure water, discharging the polyaluminum chloride, and then drying the filter. can do.

  Regarding the material of the filter, when producing a filter having a positive zeta potential by cationizing the base material, the base material is an anionic resin or non-woven fabric in order to stably fix the cationizing agent on the surface. And the like.

  About the filter hole diameter of the filter which has a positive zeta potential, the range of 0.01-10 micrometers is suitable. Within this range, it is possible to remove coarse particles that are problematic in polishing applications. The pore size of the filter is appropriately selected according to the average particle size of the silica sol to be treated.

Treatment with a filter having a positive zeta potential In the method for producing a polishing silica sol according to the present invention, the silica sol produced by various production methods is passed through a filter having a positive zeta potential. The mode of the filter treatment is not particularly limited, and an operation of filtering the silica sol that is the liquid to be treated by the filter may be performed. Further, the processing using a filter having a positive zeta potential may be repeated.

Moreover, about the silica sol which is a to-be-processed liquid, you may add a desired process other than the process made to pass through the filter which has a positive zeta potential. An example of this is a centrifugal separation process. When the silica sol obtained by removing coarse particles from the silica sol by centrifugation and then passing it through a filter with a positive zeta potential is applied to polishing, the generation of linear traces is more effectively suppressed. It becomes possible to do.

  In order to produce the above-described polishing silica sol according to the present invention, for example, silica fine particles having an average particle diameter of 3 to 100 nm converted from a specific surface area measured by a nitrogen adsorption method (or sodium titration method) are 1 to 1. A silica sol dispersed in a dispersion medium in a range of 50% by mass may be passed through the filter having the positive zeta potential. The magnitude of the zeta potential of the filter can be appropriately determined according to the zeta potential of the silica fine particles contained in the silica sol. The filter pore size can also be appropriately determined according to the size of the coarse particles contained in the silica sol, the average particle size of the silica sol, and the like. Further, the number of times of processing by the filter may be appropriately adjusted so that a desired result is obtained.

When the above-mentioned polishing silica sol according to the present invention is manufactured by the above-described polishing silica sol manufacturing method, in this polishing silica sol, the average measured by the dynamic light scattering method when the silica concentration of the silica sol is 1% by mass the particle diameter and (D _1), like-average particle diameter when the 30 mass% is taken as (D _30), the concentration dependence coefficient of the average particle size given by _{(D 1) / (D 30} ), There is a tendency to be in the range of 2.0 to 2.8.

In general, the average particle diameter measured by the dynamic light scattering method tends to vary depending on the concentration of the silica sol to be measured. Therefore, the average particle diameter usually obtained differs between the case where the concentration of the silica sol to be measured is 1% by mass and 30% by mass. In a normal silica sol, the concentration dependency coefficient is in the range of 1.5 or more and less than 2.0. That is, the polishing silica sol according to the present invention produced by the method for producing a polishing silica sol has a characteristic that it has a concentration dependency coefficient larger than that of a normal silica sol.
Polishing Composition The polishing particle dispersion according to the present invention can be used as an abrasive by itself, but if desired, as an additive, a polishing accelerator, a surfactant, a heterocyclic compound, pH adjustment One or more selected from the group consisting of an agent and a pH buffer may be added and used. In the present invention, a mixture obtained by adding these components to the polishing particle dispersion is referred to as “polishing composition”.
Polishing Accelerator For the polishing composition according to the present invention, a conventionally known polishing accelerator can be used as necessary, although it varies depending on the type of material to be polished. Examples of such include hydrogen peroxide, peracetic acid, urea peroxide 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.

  As another example of the polishing accelerator, there can be mentioned acids such as sulfuric acid, nitric acid, phosphoric acid, oxalic acid and hydrofluoric acid, or sodium salts, potassium salts, ammonium salts and mixtures thereof. In the case of a polishing composition containing these polishing accelerators, when polishing a material to be polished consisting of composite components, the polishing rate is accelerated for a specific component of the material to be polished, thereby finally achieving flat polishing. You can get a plane.

When the polishing composition according to the present invention contains a polishing accelerator, the content thereof is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass.
Surfactant and / or hydrophilic compound In order to improve the dispersibility and stability of the polishing composition, a cationic, anionic, nonionic or amphoteric surfactant or hydrophilic compound can be added. Both the surfactant and the hydrophilic compound have an action of reducing a contact angle to the surface to be polished and an action of promoting uniform polishing. As the surfactant and / or the hydrophilic compound, for example, those selected from the following groups can be used.

  Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. As the carboxylate salt, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxyl Acid salt, acylated peptide; as sulfonate, alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, naphthalene sulfonate, sulfosuccinate, α-olefin sulfonate, N-acyl sulfonate; sulfate ester Salts include sulfated oil, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates; phosphate ester salts such as alkyl phosphates, polyoxyethylene or polyoxy B pyrene alkyl allyl ether phosphate can be exemplified.

  As cationic surfactant, aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt; as amphoteric surfactant, carboxybetaine type, sulfobetaine type, Mention may be made of aminocarboxylates, imidazolinium betaines, lecithins, alkylamine oxides.

  Nonionic surfactants include ether type, ether ester type, ester type and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene poly Examples include oxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, ether ester type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, ester type, Polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester Le, sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, etc. are exemplified, and other fluorine-based surfactant and the like.

  As the surfactant, an anionic surfactant or a non-ionic surfactant is preferable, and as the salt, ammonium salt, potassium salt, sodium salt and the like can be mentioned, and ammonium salt and potassium salt are particularly preferable.

Further, other surfactants and hydrophilic compounds include 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 Ethers such as glycol, alkyl polypropylene glycol alkyl ether, alkyl polypropylene glycol alkenyl ether, alkenyl polypropylene glycol; polysaccharides such as alginic acid, pectic acid, carboxymethyl cellulose, curdlan and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; Polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), poly Acrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic acid ammonium salt, polyacrylic acid sodium salt Polycarboxylic acids such as polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt, and polyglyoxylic acid and salts thereof; vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrolein; methyl tauric acid ammonium salt, methyl tauric acid sodium salt , Methyl sulfate sodium salt, ethyl ammonium sulfate salt, butyl ammonium sulfate salt, vinyl sulfonic acid sodium salt, 1-allyl sulfonic acid sodium salt, 2-allyl sulfonic acid sodium salt, methoxymethyl sulfonic acid sodium salt, ethoxymethyl sulfonic acid ammonium salt Salts, sulfonic acids such as sodium 3-ethoxypropyl sulfonate and salts thereof; propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide and sulfo Examples thereof include amides such as fanilamide.

  In addition, when the substrate to be polished is a glass substrate or the like, any surfactant can be suitably used. However, in the case of a silicon substrate for a semiconductor integrated circuit or the like, alkali metal, alkaline earth When the influence of contamination by metals or halides is disliked, it is desirable to use an acid or an ammonium salt surfactant.

  When the polishing composition according to the present invention contains a surfactant and / or a hydrophilic compound, the total content is preferably 0.001 to 10 g in 1 L of the polishing composition, It is more preferably 0.01 to 5 g, and particularly preferably 0.1 to 3 g.

  In order to obtain a sufficient effect, the content of the surfactant and / or the hydrophilic compound is preferably 0.001 g or more in 1 L of the polishing composition, and preferably 10 g or less from the viewpoint of preventing the polishing rate from being lowered.

Only one type of surfactant or hydrophilic compound may be used, two or more types may be used, and different types may be used in combination.
Means only the atoms that form part of the ring system of the ring and is located external to the ring system, separated from the ring system by at least one non-conjugated single bond, or further substituents of the ring system An atom that is part of is not meant. Preferred examples of the hetero atom include, but are not limited to, a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom. As examples of the heterocyclic compound, imidazole, benzotriazole, benzothiazole, tetrazole, 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 can be mentioned, but is not limited thereto.

About content in the case of mix | blending a heterocyclic compound with the polishing composition which concerns on this invention, it is preferable that it is 0.001-1.0 mass%, and it is 0.001-0.7 mass%. More preferably, the content is 0.002 to 0.4% by mass.
pH adjuster In order to enhance the effect of each of the above additives, an acid or a base can be added as necessary to adjust the pH of the polishing composition.

When adjusting the polishing composition to pH 7 or higher, an alkaline one is used as a pH adjuster. Desirably, amines such as sodium hydroxide, aqueous ammonia, ammonium carbonate, ethylamine, methylamine, triethylamine, tetramethylamine are used.

When adjusting the polishing composition to less than pH 7, an acidic one is used as a pH adjuster. For example, hydroxy acids such as lactic acid, citric acid, malic acid, tartaric acid and glyceric acid are used.
pH buffering agent In order to keep the pH value of the polishing composition constant, a pH buffering agent may be used. As the pH buffering agent, for example, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, tetraborate ammonium tetrahydrate water phosphate and borate or organic acid can be used.
Solvent For the polishing composition according to the present invention, a solvent can be used as necessary. As the solvent, water is usually used, but alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol can be used as necessary, and water-soluble organic solvents such as ethers, esters, and ketones are also used. be able to. Further, it may be a mixed solvent composed of water and an organic solvent.
Concentration of polishing particles The concentration of silica fine particles in the polishing composition is preferably in the range of 2 to 50 wt%, more preferably 5 to 30 wt%. If the concentration is less than 2% by weight, the concentration may be too low depending on the type of substrate or insulating film, resulting in a slow polishing rate and productivity. If the concentration of silica particles exceeds 50% by weight, the stability of the abrasive will be insufficient, the polishing rate and the polishing efficiency will not be further improved, and the dried product will be removed in the step of supplying the dispersion for polishing treatment. It may be generated and attached, which may cause scratches.
〔Example〕
The measurement methods used in Examples and Comparative Examples are described below.
[Measuring method of average particle size by dynamic light scattering method]
Regarding the average particle size of the silica fine particles, silica sol was diluted with 0.58% ammonia water to adjust the silica concentration to 1% by mass or 30% by mass, and the average particle size was measured using the following particle size measuring apparatus. .
[Particle size measuring device]
Laser particle analyzer (manufactured by Otsuka Electronics Co., Ltd., laser particle size analysis system: LP-510 model PAR-III, measurement principle: dynamic light scattering method, measurement angle 90 °, light receiving element: photomultiplier tube 2 inches, measurement range: 3 nm to 5 μm, light source: He—Ne laser (5
mW, 632.8 nm), temperature adjustment range: 5 to 90 ° C., temperature adjustment method: Peltier element (cooling), ceramic heater (heating), cell: 10 mm square plastic cell, measurement object: colloidal particles)
[Preparation of filter with positive zeta potential]
An aqueous solution (polyaluminum chloride 5 mass%) in which polyaluminum chloride was dissolved in pure water was filled in a capsule filter (product number: DFA4201J012F, made of polypropylene, filter pore size 1.2 μm) manufactured by Nippon Pole Co., Ltd., and left for 1 hour.

  Then, it was passed with pure water until the electric conductivity in the capsule filter became 10 μs or less, and the remaining polyaluminum chloride was discharged. Here, an electrical conductivity meter (ES-51 manufactured by Horiba, Ltd.) was used for measuring the electrical conductivity.

After washing with pure water, the capsules were disassembled, and the filter was taken out from the pure water and dried at 80 ° C. overnight. Subsequently, a part of the filter (rectangular shape of 15 mm × 35 mm) was collected and applied to a zeta potential / particle size measurement system ELSZ-1 (manufactured by Otsuka Electronics Co., Ltd.) and a cell unit for flat sample (manufactured by Otsuka Electronics Co., Ltd.) The zeta potential on the filter surface was measured to find + 8m
V and it was confirmed that the surface was cationized.

In the following examples, a filter having a positive zeta potential (hereinafter referred to as “cationizing filter”) prepared by this method was used. Note that the zeta potential of the filter before the cationization treatment was −18 mV.
[Measurement of silica content in silica sol]
2 ml of 50% sulfuric acid aqueous solution was added to 10 g of sample silica sol and evaporated to dryness on a platinum pan. The obtained solid was baked at 1000 ° C. for 1 hour, then cooled and weighed. Next, dissolve the weighed solid in a small amount of 50% aqueous sulfuric acid, add 20 ml of hydrofluoric acid, evaporate to dryness on a platinum pan, bake at 1000 ° C. for 15 minutes, and cool. Weighed. The silica content in the porous silica particles was determined from these weight differences.
[Quantification method of dissolved silica component]
Centrifuge tube with separation membrane (VARTASPIN VS200, manufactured by Sartorius Biolab)
1: A sample (polishing silica sol) was placed in a separation membrane fraction molecular weight of 10000), and the sample was covered. This centrifuge tube was attached to a centrifugal separator (KUBOTA 6930, Kubota Seisakusho), and centrifuged at a centrifugal force of 4500 G for 90 minutes. By this centrifugation treatment, the solvent (including components dissolved in the solvent) passed through the separation membrane and was collected in the lower part of the centrifuge tube, and the solvent was separated from the silica sol. About the collect | recovered solvent, the amount of dissolved silica components was quantified by the molybdenum reaction, and the molecular weight was measured by GPC. The amount of Na ₂ O was quantified by the atomic absorption method described later.
[Quantification method of dissolved silica component by molybdenum reaction]
1) 200 ml of water was taken in a 300 ml beaker and adjusted to pH = 1 with HCl.
2) As a sample, 1 g of the solvent separated from the silica sol by centrifugation in the method for quantifying the dissolved silica component was weighed and transferred to a 300 ml beaker.
3) Adjusted again to pH = 1.
4) 10 ml of 10% ammonium molybdate was added and mixed.
5) Transfer to a 250 ml volumetric flask and adjust to 250 ml.
6) After being left for 20 minutes, the transmittance was measured at a wavelength of 420 nm.
7) The transmittance was converted to absorbance, and the SiO ₂ concentration was determined from the calibration curve. The calculation formula is as follows.

Dissolved silica (SiO ₂ ) = SiO ₂ (mg) × 1000 / sample (g) × 1000000 (ppm)
8) A blank test (in which 10% ammonium molybdate was not added to the sample solution) was similarly performed and corrected.
[Method of quantifying Na ₂ O (atomic absorption method)]
1) About 10 g of sample silica sol was collected in a platinum dish and weighed to 0.1 mg.
2) 5 ml of nitric acid and 20 ml of hydrofluoric acid were added, heated on a sand bath, and evaporated to dryness. 3) When the amount of liquid decreased, 20 ml of hydrofluoric acid was further added and heated on a sand bath to evaporate to dryness.
4) After cooling to room temperature, 2 ml of nitric acid and about 50 ml of water were added and dissolved by heating on a sand bath. 5) After cooling to room temperature, it was put into a flask (100 ml) and diluted to 100 ml with water to obtain a sample solution.
6) Atomic absorption spectrophotometer (manufactured by Hitachi, Ltd., Z-5300, measurement mode: atomic absorption, measurement wavelength: 190 to 900 nm, detection wavelength of Na in the case of silica sample is 589.0 nm), sample solution The content of each metal present therein was measured. This atomic absorption spectrophotometer vaporizes a sample with a frame, irradiates the atomic vapor layer with light of an appropriate wavelength, and measures the intensity of light absorbed by the atoms at that time. The elemental concentration of is determined.
[Specific surface area measurement and average particle diameter measurement by nitrogen adsorption method]
A sample prepared by adjusting 50 ml of silica sol to pH 3.5 with HNO ₃ , adding 40 ml of 1-propanol, drying at 110 ° C. for 16 hours, pulverizing in a mortar, baking at 500 ° C. for 1 hour in a muffle furnace, and measuring sample It was. And the specific surface area was computed by the BET 1 point method from the adsorption amount of nitrogen using the nitrogen adsorption method (BET method) using the specific surface area measuring apparatus (The product made from Yuasa Ionics, model number multisorb 12).

Specifically, 0.5 g of a sample is taken in a measurement cell, degassed for 20 minutes at 300 ° C. in a mixed gas stream of nitrogen 30 v% / helium 70 v%, and then the sample is liquidized in the mixed gas stream. Keep nitrogen temperature and allow nitrogen to equilibrate to sample. Next, the sample temperature was gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that time was detected, and the specific surface area of the silica sol was calculated using a calibration curve prepared in advance. The average particle diameter (D) [nm] is obtained from the above formula (5).
[Evaluation method of polishing characteristics]
Polishing Substrate An aluminum disk substrate was used as the polishing substrate. This aluminum disk substrate is a substrate (95 mmΦ / 25 mmΦ-1.27 mmt) obtained by electrolessly plating Ni-P to a thickness of 10 μm (a hard Ni-P plating layer having a composition of Ni88% and P12%) on an aluminum substrate. It was used. This substrate was first polished and the surface roughness (Ra) was 0.17 nm.
Polishing test The above substrate to be polished is set in a polishing apparatus (manufactured by Nano Factor Co., Ltd .: NF300), and a polishing pad (“Apollon” manufactured by Rodel) is used and polished at a substrate load of 0.05 MPa and a table rotation speed of 30 rpm. Polishing was performed by supplying the slurry for 5 minutes at a rate of 20 g / min. The polishing rate was calculated by determining the weight change of the substrate to be polished before and after polishing.
Regarding the occurrence of scratches on the linear traces, after polishing the substrate for the aluminum disk in the same manner as described above, the entire surface with Zoom 15 using an ultra-fine defect / visualization macro device (VISION PSYTEC: Micro-MAX) The number of linear marks (scratches) on the surface of the polished substrate corresponding to 65.97 cm ² was counted and totaled, and displayed as the number of (linear marks) / sheet.
Polishing rate By dividing the weight difference (g) of the substrate before and after polishing by the specific gravity (8.4 g / cm ³ ), and further dividing by the substrate surface area (65.97 cm ² ) and the polishing time, the polishing amount per unit time ( nm / min) was calculated.
200 g of concentrated stable silica sol (silica concentration: 30% by mass) was placed in a 500 ml eggplant flask and placed on a rotary evaporator. After setting the bath temperature to 60 ° C., concentration was performed at a vacuum degree of −740 mmHg. When a gel-like substance was found on the inner wall surface of the eggplant flask, the concentration was stopped and the silica sol was recovered, and the SiO ₂ concentration was measured. (The higher the concentration stability, the higher the concentration is possible, and no gel-like material is generated even when the concentration is high.)

(Preparation of silicic acid solution)
7,000 g of 7% sodium silicate (No. 3 water glass) was passed through an ultra module (SIP-1013 manufactured by Asahi Kasei Co., Ltd.) and the filtrate was collected to obtain purified water glass. Pure water was added so that the silica concentration of the purified water glass was 5%. And this water glass 6,500g of silica concentration 5%
Was passed through 2.2 L of strongly acidic cation exchange resin SK1BH (manufactured by Mitsubishi Chemical Corporation) at a space velocity of 3.1 to obtain 6,650 g of a silicic acid solution.
The silica concentration of the obtained silicic acid solution was 4.7%.
(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, 20.1 g of a silica solution having a silica concentration of 4.7% by mass was added and stirred, and then the temperature was raised to 82 ° C. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration became 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
[Filtration using cationized filter]
The cationized filter was attached to a pressure device, and the silica sol obtained above was passed once under a pressure condition of 0.16 MPa.
The obtained silica sol A for polishing had a specific surface area of 103 m ² / g measured by a nitrogen adsorption method.
Further, (S2) / (S1) [ppm] in the silica sol A for polishing was 839 ppm.
Other measurement results (from silica concentration of polishing silica sol, Na ₂ O concentration, mass of total silica component present in silica sol (S1), mass of dissolved silica component (S2), concentration dependence coefficient of average particle diameter, specific surface area The converted average particle diameter and the like are shown in Table 1 (the same applies to the following Examples and Comparative Examples).
[Preparation of polishing composition]
H ₂ O ₂ , HEDP (1-hydroxyethylidene-1,1-disulfonic acid) and ultrapure water are added to the silica sol A for polishing, and 9% by mass of silica, 0.5% by mass of H ₂ O ₂ , 1- A polishing slurry containing 0.5% by mass of hydroxyethylidene-1,1-disulfonic acid was prepared, and HNO ₃ was prepared.
Was added to prepare a polishing slurry adjusted to pH 2, that is, a polishing composition A.

  The polishing properties were evaluated using the polishing composition A, and the polishing rate, the number of linear marks and the concentration stability were determined. These results are shown in Table 2.

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, a silica solution 20.1 having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was used.
After adding g and stirring, it heated up at 82 degreeC. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
[Filtration using cationized filter]
The cationized filter obtained by the treatment shown in the previous section was attached to a pressure apparatus, and the silica sol obtained above was passed twice. The obtained polishing silica sol B had a specific surface area of 101 m ² / g measured by a nitrogen adsorption method.

Moreover, (S2) / (S1) [ppm] in the silica sol B for polishing was 762 ppm.
[Preparation of polishing composition]
A polishing slurry, that is, a polishing composition B, was prepared in the same manner as in Example 1 except that the polishing silica sol B was used instead of the polishing silica sol A.

The polishing characteristics were evaluated using the polishing composition B, and the polishing rate, the number of linear marks, and the concentration stability were determined. These results are shown in Table 2.

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, a silica solution 20.1 having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was used.
After adding g and stirring, it heated up at 82 degreeC. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
[Filtration using cationized filter]
The cationized filter obtained by the treatment shown in the previous section was attached to a pressure type apparatus, and the silica sol obtained above was passed three times. The obtained silica sol C for polishing had a specific surface area of 102 m ² / g measured by the nitrogen adsorption method, and the content of Na 2 O as a solvent separated in the same manner as in Example 1 was 0.137% by mass.

Moreover, (S2) / (S1) [ppm] in the silica sol C for polishing was 740 ppm.
[Preparation of polishing composition]
A polishing slurry, that is, a polishing composition C, was prepared in the same manner as in Example 1 except that the polishing silica sol C was used instead of the polishing silica sol A.

  The polishing properties were evaluated using the polishing composition C, and the polishing rate, the number of linear marks, and the concentration stability were determined. These results are shown in Table 2.

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Subsequently, 17.4 g of a silicic acid solution having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was added and stirred, and then the temperature was raised to 82 ° C. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
[Filtration using cationized filter]
The cationized filter obtained by the treatment shown in the previous section was attached to a pressure apparatus, and the silica sol obtained above was passed once. The obtained silica sol D for polishing had a specific surface area of 101 m ² / g measured by a nitrogen adsorption method.
Moreover, (S2) / (S1) [ppm] in the silica sol D for polishing was 811 ppm.
[Preparation of polishing composition]
A polishing slurry, that is, a polishing composition D, was prepared in the same manner as in Example 1 except that the polishing silica sol D was used instead of the polishing silica sol A.

The polishing characteristics were evaluated using the polishing composition D, and the polishing rate, the number of linear marks and the concentration stability were determined. These results are shown in Table 2.

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, 22.7 g of a silica solution having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was added and stirred, and then the temperature was raised to 82 ° C. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
[Filtration using cationized filter]
The cationized filter obtained by the treatment shown in the previous section was attached to a pressure apparatus, and the silica sol obtained above was passed once. The obtained polishing silica sol E had a specific surface area of 104 m ² / g measured by a nitrogen adsorption method.
Moreover, (S2) / (S1) [ppm] in the silica sol E for polishing was 928 ppm.
[Preparation of polishing composition]
A polishing slurry E, that is, a polishing composition E, was prepared in the same manner as in Example 1 except that the polishing silica sol E was used instead of the polishing silica sol A.

The polishing characteristics were evaluated using the polishing composition E, and the polishing rate, the number of linear marks, and the concentration stability were determined. These results are shown in Table 2.
[Comparative Example 1]

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, a silica solution 20.1 having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was used.
After adding g and stirring, it heated up at 82 degreeC. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.
The obtained silica sol F had a surface area of 106 m ² / g measured by a nitrogen adsorption method.
Moreover, (S2) / (S1) [ppm] in silica sol F was 1153 ppm.
[Preparation of polishing composition]
A polishing slurry, that is, a polishing composition F, was prepared in the same manner as in Example 1 except that the silica sol F was used instead of the polishing silica sol A.

The polishing properties were evaluated using the polishing composition F, and the polishing rate, the number of linear marks, and the concentration stability were determined. These results are shown in Table 2.
[Comparative Example 2]

(Preparation of silica sol)
Pure water 1217 was added to 80.1 g of sodium silicate (No. 3 water glass SiO ₂ concentration 24.31 wt%).
. 87.9 g was added to prepare 1297.9 g of a sodium silicate aqueous solution having a silica concentration of 1.5% by mass. Next, a silicic acid solution 17.4 having a silica concentration of 4.7% by mass similar to that prepared in Example 1 was used.
After adding g and stirring, it heated up at 82 degreeC. This temperature was maintained at 82 ° C. for 30 minutes, and 11064.8 g of a silicic acid solution having a silica concentration of 4.7% by weight was added over 15 hours. After completion of the addition, the temperature was further maintained at 82 ° C. for 1 hour, and then cooled to room temperature. The obtained silica sol was concentrated with an ultrafiltration membrane (SIP-1013, manufactured by Asahi Kasei Co., Ltd.) until the silica concentration was 12%, and adjusted to pH 10 by adding a 5 mass% aqueous solution of sodium hydroxide. Subsequently, it concentrated to the silica concentration of 30 weight% with the rotary evaporator.

The obtained silica sol G had a specific surface area measured by a nitrogen adsorption method of 104 m ² / g.
Further, (S2) / (S1) [ppm] in silica sol G was 1095 ppm.
[Preparation of polishing composition]
A polishing slurry, that is, a polishing composition G, was prepared in the same manner as in Example 1 except that the silica sol G was used instead of the polishing silica sol A.

    The polishing characteristics were evaluated using the polishing composition G, and the polishing rate, the number of linear marks, and the concentration stability were determined. These results are shown in Table 2.

  The polishing silica sol or polishing composition obtained by the method for producing a polishing silica sol of the present invention is excellent in polishing rate, surface roughness of the substrate to be polished, or suppression of occurrence of linear marks on the substrate to be polished. In particular, the present invention is applicable as an abrasive for aluminum substrates, glass substrates, copper substrates, silicon substrates, and the like. In addition, it can be applied to a wide range of uses such as an additive for an ink receiving layer, an antibacterial additive based on water repellency, a coating additive, and a toner component.

Claims (4)

  A silica sol in which silica fine particles having an average particle diameter of 3 to 100 nm converted from a specific surface area measured by a nitrogen adsorption method are dispersed in a solvent in a silica concentration range of 1 to 50% by mass, and the silica sol When the mass of all silica components present is (S1) and the mass of dissolved silica components dissolved in the solvent is (S2), the value of (S2) / (S1) [ppm] is 1000 ppm or less. A polishing silica sol characterized by When the average particle size measured by the dynamic light scattering method when the silica concentration of the silica sol is 1% by mass is (D ₁ ) and the average particle size when the silica concentration is 30% by mass is also (D ₃₀ ), 2. The polishing silica sol according to claim 1, wherein the concentration dependency coefficient of the average particle diameter given by (D ₁ ) / (D ₃₀ ) is in the range of 2.0 to 2.8.   A polishing silica sol according to claim 1 or 2, (a) a polishing accelerator, (b) a surfactant, (c) a hydrophilic compound, (d) a heterocyclic compound, (e) a pH adjuster and ( f) Polishing composition containing at least one selected from the group consisting of pH buffering agents. A method for producing a polishing silica sol, comprising passing a silica sol obtained by dispersing silica fine particles in a solvent through a filter having a positive zeta potential.