JP6603142B2 - Silica composite fine particle dispersion, method for producing the same, and polishing slurry containing silica composite fine particle dispersion - Google Patents

Description

  The present invention relates to a silica-based composite fine particle dispersion, a method for producing the same, and a polishing slurry containing the silica-based composite fine particle dispersion, and particularly to a polishing slurry that exhibits a high polishing rate and high surface accuracy.

In semiconductor devices such as a semiconductor substrate and a wiring substrate, the surface state affects the semiconductor characteristics, and therefore, it is required to polish the surfaces and end faces of these components with extremely high accuracy.
Conventionally, as a polishing method for such a member, after performing a relatively rough primary polishing process, and then performing a precise secondary polishing process, a smooth surface or a highly accurate surface with few scratches such as scratches can be obtained. The way to get done.
Conventionally, for example, the following methods have been proposed for the abrasive used for the secondary polishing as the finish polishing.

  Patent Document 1 is characterized in that an aqueous solution of cerium nitrate and a base are stirred and mixed in an amount ratio of pH 5 to 10, followed by rapid heating to 70 to 100 ° C. and aging at that temperature. Describes a method for producing ultrafine cerium oxide particles comprising a cerium oxide single crystal having a particle size of 10 to 80 nm. And by such a manufacturing method, it is possible to provide cerium oxide ultrafine particles that not only have an average particle size of 10 to 80 nm, but also have a uniform particle size and the same shape as possible. It is described.

  Further, Non-Patent Document 1 is a method for producing ceria-coated silica similar to the production method described in Patent Document 1, and does not have a firing-dispersing step in the production method described in Patent Document 1. A manufacturing method is described.

  Furthermore, Patent Document 2 discloses that the surface of the amorphous silica particles A has at least one selected from zirconium, titanium, iron, manganese, zinc, cerium, yttrium, calcium, magnesium, fluorine, lanthanum, and strontium. A silica-based composite particle characterized by having a crystalline oxide layer B containing an element is described. As a preferred embodiment, an amorphous oxide layer containing an element such as aluminum on the surface of the amorphous silica particles A, which is different from the amorphous silica layer A crystalline oxide layer having C and further containing one or more elements selected from zirconium, titanium, iron, manganese, zinc, cerium, yttrium, calcium, magnesium, fluorine, lanthanum, and strontium Silica-based composite particles characterized by having B are described. And since such a silica type composite particle has the crystalline oxide layer B on the surface of the amorphous silica particle A, it can improve a grinding | polishing speed and pre-process on a silica particle. By suppressing the sintering of particles during firing, the dispersibility in the polishing slurry can be improved, and further, the amount of cerium oxide used can be greatly reduced without containing cerium oxide. Therefore, it is described that it is possible to provide an abrasive that is inexpensive and has high polishing performance. Further, those having an amorphous oxide layer C between the silica-based particles A and the oxide layer B are described as being particularly excellent in the effect of suppressing the sintering of the particles and the effect of improving the polishing rate. Yes.

Japanese Patent No. 2746861 JP 2013-119131 A

Seung-Ho Lee, Zhenyu Lu, S .; V. Babu and Egon Matijevic, “Chemical mechanical polishing of thermal oxide films using sir te sir te s i s e s s e s e s e n e s e s e n i e s e s e e n e s e n e s e n e i e n e s e i e n e e m e n e s e i e m e n e n i e n e n i e n i e n i e n i e n i e n i e n i e n i e n i e n i e n i e n i n e n e n i.

  However, the cerium oxide ultrafine particles described in Patent Document 1 were actually manufactured and examined by the inventor, and the polishing rate was low. Further, the surface of the polishing base material had defects (deterioration of surface accuracy, increased scratches, It has been found that the residue of the abrasive on the surface of the polishing substrate tends to occur. The present inventor presumes that this is mainly due to the fact that the ceria particles are only crystallized from the liquid phase and remain on the surface of the polishing substrate due to the fact that the crystallinity of the ceria particles is low compared to the firing method. is doing.

  In addition, since the ceria-coated silica described in Non-Patent Document 1 is not fired, it is considered that the actual polishing rate is low, and there is a concern that particles remain on the surface of the polishing substrate.

  Furthermore, when polishing using the silica-based composite particles having the oxide layer C described in Patent Document 2, impurities such as aluminum remain on the surface of the semiconductor device, which may adversely affect the semiconductor device. The inventor found out.

  An object of the present invention is to solve the above problems. That is, according to the present invention, even a Si wafer or a difficult-to-process material can be polished at high speed, and at the same time, high surface accuracy (low scratch, low Ra on the substrate surface) can be achieved, and further, no impurities are contained. An object of the present invention is to provide a silica-based composite fine particle dispersion that can be preferably used for polishing the surface of a semiconductor device such as a substrate or a wiring substrate, a method for producing the same, and a polishing slurry containing the silica-based composite fine particle dispersion.

The inventor has intensively studied in order to solve the above problems, and has completed the present invention.
The present invention includes the following (1) to (5).
(1) An average particle diameter of 50 having the following characteristics [1] to [4], wherein child particles mainly composed of crystalline ceria are bonded to the surface of mother particles mainly composed of amorphous silica. A silica-based composite fine particle dispersion containing silica composite fine particles of ˜350 nm.
[1] The silica-based composite fine particles have a mass ratio of silica and ceria of 100: 11 to 316.
[2] When the silica-based composite fine particles are subjected to X-ray diffraction, only the ceria crystal phase is detected.
[3] When the silica-based composite fine particles are subjected to X-ray diffraction, the crystallite diameter of the (111) plane of the crystalline ceria is 10 to 25 nm.
[4] The silica composite fine particles have a ratio of the number of particles having a minor axis / major axis ratio of 0.8 or less as measured by an image analysis method of 50% or more.
(2) In the silica-based composite fine particles, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr is 100 ppm or less, U, The silica-based composite fine particle dispersion as described in (1) above, wherein the contents of Th, Cl, NO ₃ , SO ₄ and F are each 5 ppm or less.
(3) A polishing slurry comprising the silica-based composite fine particle dispersion described in (1) or (2).
(4) A method for producing a silica-based composite fine particle dispersion, comprising the following step 1 and step 2.
Step 1: A silica sol in which silica fine particles are dispersed in a solvent is continuously or intermittently maintained while stirring at a temperature of 5 to 98 ° C. and a pH range of 7.0 to 9.0. Adding to obtain a precursor particle dispersion containing the precursor particles.
Step 2: After the pH of the precursor particle dispersion is adjusted to 6.0 to 7.0, the precursor particle dispersion is dried and fired at 400 to 1,200 ° C., and then subjected to dry crushing / pulverization and solvent dispersion. The process of obtaining the silica type composite fine particle dispersion as described in said (1) by performing or crushing and grinding | pulverization by wet.
(5) As the silica sol in the step 1, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr is 100 ppm or less, U, The silica-based composite fine particle dispersion described in (4) above, wherein a silica sol in which silica fine particles each containing 5 ppm or less of Th, Cl, NO ₃ , SO ₄ and F are dispersed in a solvent is used. Manufacturing method.

  According to the present invention, even a Si wafer or a difficult-to-process material can be polished at high speed, and at the same time, high surface accuracy (low scratch, low Ra on the substrate surface) can be achieved, and further, no impurities are contained. A silica-based composite fine particle dispersion that can be preferably used for polishing a surface of a semiconductor device such as a substrate or a wiring board, a method for producing the same, and a polishing slurry containing the silica-based composite fine particle dispersion can be provided.

1A is an SEM image obtained in Example 1, and FIGS. 1B and 1C are TEM images obtained in Example 1. FIG. 2 is an X-ray diffraction pattern obtained in Example 1. FIG. 3A is an SEM image obtained in Example 5, and FIG. 3B is a TEM image obtained in Example 6. 7 is an X-ray diffraction pattern obtained in Example 5. 5A is an SEM image obtained in Comparative Example 4, and FIG. 5B is a TEM image obtained in Comparative Example 4. 7 is an X-ray diffraction pattern obtained in Comparative Example 4.

The present invention will be described.
In the present invention, an average particle diameter having the following features [1] to [4], wherein child particles mainly composed of crystalline ceria are bonded to the surface of mother particles mainly composed of amorphous silica. A silica-based composite fine particle dispersion containing silica-based composite fine particles of 50 to 350 nm.
[1] The silica-based composite fine particles have a mass ratio of silica and ceria of 100: 11 to 316.
[2] When the silica-based composite fine particles are subjected to X-ray diffraction, only the ceria crystal phase is detected.
[3] When the silica-based composite fine particles are subjected to X-ray diffraction, the crystallite diameter of the (111) plane of the crystalline ceria is 10 to 25 nm.
[4] The silica composite fine particles have a ratio of the number of particles having a minor axis / major axis ratio of 0.8 or less as measured by an image analysis method of 50% or more.
Hereinafter, such a silica-based composite fine particle dispersion is also referred to as “the dispersion of the present invention”.
Further, the silica-based composite fine particles contained in the dispersion of the present invention are also referred to as “composite fine particles of the present invention” below.

In the silica-based composite fine particle dispersion of the present invention, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr of the silica-based composite fine particle is respectively It is preferably 100 ppm or less, and the contents of U, Th, Cl, NO ₃ , SO ₄ and F are each preferably 5 ppm or less.
Furthermore, the present invention is a polishing slurry containing the silica-based composite fine particle dispersion of the present invention.

Moreover, this invention is a manufacturing method of the silica type composite fine particle dispersion liquid which is equipped with the following process 1 and process 2, and the dispersion liquid of this invention is obtained.
Step 1: A silica sol in which silica fine particles are dispersed in a solvent is continuously or intermittently maintained while stirring at a temperature of 5 to 98 ° C. and a pH range of 7.0 to 9.0. Adding to obtain a precursor particle dispersion containing the precursor particles.
Step 2: After the pH of the precursor particle dispersion is adjusted to 6.0 to 7.0, the precursor particle dispersion is dried and fired at 400 to 1,200 ° C., and then subjected to dry crushing / pulverization and solvent dispersion. The process of obtaining the dispersion liquid of this invention by performing or performing crushing and grinding | pulverization by wet.
Hereinafter, the method for producing such a silica-based composite fine particle dispersion is also referred to as “the production method of the present invention”.
In addition, as a silica sol of the said process 1 in the manufacturing method of this invention, the content rate of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr is 100 ppm or less, respectively. It is preferable to use a silica sol in which silica fine particles each containing 5 ppm or less of U, Th, Cl, NO ₃ , SO ₄ and F are dispersed in a solvent.

  The dispersion of the present invention is preferably produced by the production method of the present invention.

  In the following, the simple description of “the present invention” means any of the dispersion of the present invention, the composite fine particles of the present invention, and the production method of the present invention.

  The composite fine particles of the present invention will be described.

<Mother particles>
In the composite fine particles of the present invention, the mother particles are mainly composed of amorphous silica.

  When the mother particles are pulverized using a mortar and an X-ray diffraction pattern is obtained using, for example, a conventionally known X-ray diffractometer (for example, RINT1400, manufactured by Rigaku Corporation), a crystalline silica peak such as cristobalite does not appear. . That is, it can be confirmed that the silica contained in the mother particles is amorphous. The pulverization of the mother particles is usually applied to a pulverization treatment by drying a silica sol in which the mother particles are dispersed in a solvent.

The “main component” means that the content is 90% by mass or more. That is, in the mother particles, the content of amorphous silica is 90% by mass or more.
This content is preferably 95% by mass or more, more preferably 98% by mass or more, preferably 99.5% by mass or more, and more preferably 100% by mass. In the following description of the present invention, “main component” is used in this sense.

  Although the mother particles are mainly composed of amorphous silica, they may contain crystalline silica or an impurity element as long as the effects of the present invention are not hindered. The content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr in the mother particles is preferably 100 ppm or less, and 50 ppm or less. Is more preferably 25 ppm or less, even more preferably 5 ppm or less.

Further, the content of each element of U, Th, Cl, NO ₃ , SO ₄ and F in the mother particles is preferably 5 ppm or less.

  About the measuring method of the content rate of said each element in a mother particle, it is as having described in the Example.

As will be described later, the average particle size of the silica-based composite fine particles according to the present invention is in the range of 50 to 350 nm, and the average particle size of the mother particles is necessarily smaller than 350 nm. In addition, in this application, let the average particle diameter of the silica sol used at the below-mentioned process 1 be an average particle diameter of a mother particle. Silica-based composite fine particles having an average particle diameter of 30 to 200 nm are preferably used.
When the average particle diameter of the mother particles is in the above range, scratches are reduced when the dispersion of the present invention is used as an abrasive. If the average particle size of the mother particles is too small, the polishing rate will be insufficient. When the average particle diameter is too large, scratches are generated and the surface accuracy of the substrate tends to deteriorate.

  The average particle diameter of the mother particles is measured using a known dynamic light scattering particle diameter measuring apparatus (for example, Nikkiso Co., Ltd., Microtrac UPA apparatus or Otsuka Electronics PAR-III).

The shape of the mother particles is not particularly limited, and for example, spherical, bowl-like, short fiber-like, tetrahedron (triangular pyramid), hexahedron, octahedron, plate, indeterminate and hook-like projections on the surface It may be a saccharide, a confetti-like one, or a porous one, but a spherical one is preferred. Spherical shape means that the ratio of the number of particles with a minor axis / major axis ratio of 0.8 or less is 10% or less. The mother particles preferably have a minor axis / major axis ratio of 0.8 or less and a number ratio of particles of 5% or less, more preferably 0%.
The minor axis / major axis ratio is measured by the same method as the measuring method (image analysis method) of the minor axis / major axis ratio of the composite fine particles of the present invention described later.

<Child particles>
In the composite fine particles of the present invention, the child particles are bonded to the surface of the mother particles as described above.

  In the composite fine particles of the present invention, the child particles are mainly composed of crystalline ceria.

When the composite fine particles of the present invention are pulverized using a mortar and an X-ray diffraction pattern is obtained by, for example, a conventionally known X-ray diffraction apparatus (for example, RINT1400, manufactured by Rigaku Corporation), only the ceria crystal phase is detected. The
Ceriaite is an example of the ceria crystal phase. The pulverization of the composite fine particles is usually applied to a pulverization treatment by drying a composite fine particle dispersion in which the composite fine particles are dispersed in a solvent.

The child particles are mainly composed of crystalline ceria (crystalline Ce oxide), and may contain other elements, for example, elements other than cerium.
However, as described above, when the composite fine particles of the present invention are subjected to X-ray diffraction, only the ceria crystal phase is detected. That is, even if a crystal phase other than ceria is included, its content is small, and thus it is outside the detection range by X-ray diffraction.
The definition of “principal component” is as described above.

  As for the child particles, the crystallite diameter of the (111) plane of the crystalline ceria measured by subjecting the silica-based composite fine particles to X-ray diffraction is 10 to 25 nm, preferably 14 to 18 nm. More preferably, it is 16 nm.

The crystallite diameter of the (111) plane of crystalline ceria means a value obtained by the method described below.
First, the composite fine particles of the present invention are pulverized using a mortar, and an X-ray diffraction pattern is obtained by using, for example, a conventionally known X-ray diffractometer (for example, RINT1400 manufactured by Rigaku Corporation). Then, the half width of the peak of the (111) plane near 2θ = 28 degrees in the obtained X-ray diffraction pattern is measured, and the crystallite diameter is obtained by the following Scherrer equation.
D = Kλ / βcos θ
D: Crystallite diameter (angstrom)
K: Scherrer constant λ: X-ray wavelength (1.7789 angstrom, Cu lamp)
β: Half width (rad)
θ: Reflection angle

The size of the child particles is smaller than that of the mother particles, preferably an average particle size of 15 to 25 nm, and more preferably 18 to 23 nm.
The size of the child particles can be any 50 particles after obtaining an average particle diameter of each particle in a photograph projection view (for example, FIG. 1C described later) enlarged 300,000 times using a transmission electron microscope. Means a value obtained by simply averaging the average particle diameter of the particles.

<Composite fine particles of the present invention>
The composite fine particles of the present invention are obtained by binding the above child particles to the surface of the above mother particles.

  In the composite fine particles of the present invention, the mass ratio of silica to ceria is 100: 11 to 316, preferably 100: 30 to 150, and more preferably 100: 60 to 120. If the amount of ceria with respect to silica is too small, the mother particles may be bonded to generate coarse particles. In this case, the abrasive (polishing slurry) containing the dispersion of the present invention may cause defects (decrease in surface accuracy such as an increase in scratches) on the surface of the polishing substrate. Further, if the amount of ceria relative to silica is too large, not only is the cost high, but the resource risk increases. Further, the fusion of particles progresses, and the particles are coarsened or ceria particles are easily released. As a result, the surface roughness of the substrate rises (Ra deteriorates), scratches increase, free ceria remains on the substrate, and it may easily cause troubles such as adhesion to the waste liquid piping of the polishing apparatus. .

In the composite fine particle of the present invention, the mother particle and the child particle are bonded. Specifically, the composite fine particles of the present invention are those in which particulate crystalline ceria (child particles) are bonded to the surface of silica fine particles (mother particles) by sintering or the like, and have an uneven surface shape. is doing.
That is, at least one (preferably both) of the mother particle and the child particle is welded at their contact points, and preferably, both are firmly bonded together.

The composite fine particles of the present invention are preferably particle-linked. The particle connection type means that two or more mother particles are partially bonded to each other. It is considered that at least one (preferably both) of the mother particles are welded at their contact points, and preferably, both are firmly bonded together. Here, in addition to the case where the child particles are bonded to the surface after the mother particles are bonded to each other, and the case where the child particles are bonded to the surface of the mother particle and then bonded to the other particles, And
In the connection type, since a large contact area with the substrate can be obtained, polishing energy can be efficiently transmitted to the substrate, so that the polishing rate is high. Further, since the polishing pressure per particle is lower than that of a single particle, there is little scratching.

In the composite fine particles of the present invention, the number ratio of particles having a minor axis / major axis ratio measured by an image analysis method of 0.80 or less (preferably 0.67 or less) is 50% or more.
Here, particles having a minor axis / major axis ratio measured by an image analysis method of 0.80 or less are considered to be of a particle-binding type in principle.

  A method for measuring the minor axis / major axis ratio by the image analysis method will be described. In a photograph projection view obtained by photographing a composite fine particle of the present invention at a magnification of 250,000 times (or 500,000 times) with a transmission electron microscope, the maximum diameter of the particles is taken as the major axis, and the length is measured. The value is taken as the major axis (DL). Further, a point that bisects the major axis on the major axis is determined, two points where a straight line perpendicular to the major axis intersects the outer edge of the particle are obtained, and the distance between the two points is measured to obtain a minor axis (DS). From this, the minor axis / major axis ratio (DS / DL) is obtained. Then, the number ratio (%) of particles having a minor axis / major axis ratio of 0.80 or less in any 50 particles observed in the photographic projection diagram is obtained.

  In the composite fine particles of the present invention, the number ratio of particles having a minor axis / major axis ratio of 0.80 or less (preferably 0.67 or less) is 50% or more, preferably 55% or more, and 65% More preferably. Composite fine particles in this range are preferable because the polishing rate increases when used as an abrasive.

  The composite fine particles of the present invention are more preferably the above-mentioned particle-linked type, but may have other shapes, for example, spherical particles.

The composite fine particles of the present invention preferably have a specific surface area of 4 to 100 m ² / g, and more preferably 30 to 60 m ² / g.

Here, a method for measuring the specific surface area (BET specific surface area) will be described.
First, a dried sample (0.2 g) is put in a measurement cell, degassed in a nitrogen gas stream at 250 ° C. for 40 minutes, and then the sample is a mixed gas of 30% by volume of nitrogen and 70% by volume of helium. Liquid nitrogen temperature is maintained in a stream of air, and nitrogen is adsorbed to the sample by equilibrium. Next, the temperature of the sample is gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that time is detected, and the specific surface area of the sample is measured using a calibration curve prepared in advance.
Such a BET specific surface area measurement method (nitrogen adsorption method) can be performed using, for example, a conventionally known surface area measurement device.
In the present invention, the specific surface area means a value obtained by such a method unless otherwise specified.

  The average particle size of the composite fine particles of the present invention is preferably 50 to 350 nm, and more preferably 170 to 260 nm. When the average particle diameter of the composite fine particles is in the range of 50 to 350 nm, it is preferable because the polishing rate increases when applied as an abrasive.

  The average particle size of the composite fine particles of the present invention was measured using a known dynamic light scattering particle size measuring device (for example, Nikkiso Co., Ltd., Microtrac UPA device or Otsuka Electronics PAR-III). It is.

  The composite fine particles according to the present invention are composed of mother particles mainly composed of amorphous silica and child particles composed of crystalline ceria. For example, crystalline silica or An impurity element may be included. In the composite fine particles of the present invention, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr is preferably 100 ppm or less. More preferably, it is 50 ppm or less, More preferably, it is 25 ppm or less, More preferably, it is 5 ppm or less.

In addition, the content of each element of U, Th, Cl, NO ₃ , SO ₄ and F in the composite fine particles of the present invention is preferably 5 ppm or less.
In the composite fine particle dispersion of the present invention, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr is 100 ppm or less, and U, Th , Cl, NO ₃ , SO _4, and F are each contained in a composite oxide fine particle dispersion characterized by being 5 ppm or less, and a composite oxide fine particle dispersion not necessarily satisfying such conditions. There may be. Among these, the former can be suitably used as an abrasive in applications where application of high-purity abrasives is required, for example, polishing applications such as semiconductor devices such as semiconductor substrates and wiring substrates. Moreover, the latter is applied to applications where application of a high-purity abrasive is not required, such as glass polishing. (The former can naturally be applied to applications where application of a high-purity abrasive is not required.)

When the composite fine particles of the present invention are observed using a scanning electron microscope (SEM), it can be confirmed that the child particles (ceria crystal particles) are bonded to the surfaces of the mother particles (silica particles). A thin coating was formed on the entire surface so as to cover the particles formed by binding the child particles to each other, and further EDS analysis confirmed that the coating was composed of a silica component.
This silica coating is considered to promote the bond (force) between the child particles (ceria crystal particles) and the mother particles (silica particles). Thus, for example, when the dispersion of the present invention is used as an abrasive (polishing slurry), it has an effect of preventing the child particles (ceria crystal particles) from falling off from the surface of the mother particles (silica particles) during polishing. it is conceivable that.
Due to such a structure (phenomenon), it is considered that when the dispersion liquid of the present invention is used as an abrasive, the polishing rate is high, and the surface accuracy and scratch are less deteriorated. Moreover, since it is baked, it is thought that there are few -OH groups on the particle | grain surface, and the particle | grain residue to a grinding | polishing base material is also few according to the influence. For example, when the substrate to be polished is a silica-based material, silanol groups (SiOH) are also present on the surface of the substrate to be polished, but when SiOH is also present on the surfaces of the abrasive particles (silica), both silanol groups react. Thus, it is considered that the abrasive particles may remain on the surface of the substrate to be polished. In addition, free ceria has a positive charge and is likely to adhere to the substrate. Therefore, the silica coating on the surface of the ceria particles as in the present invention imparts a negative charge to the ceria particles, and thus has an effect of reducing adhesion to the substrate.

<Dispersion of the present invention>
The dispersion liquid of the present invention will be described.
The dispersion liquid of the present invention is such that the composite fine particles of the present invention as described above are dispersed in a dispersion solvent.

  The dispersion of the present invention contains water and / or an organic solvent as a dispersion solvent. For example, water such as pure water, ultrapure water, or ion exchange water is preferably used as the dispersion solvent. Furthermore, the dispersion of the present invention may contain one or more selected from the group consisting of a polishing accelerator, a surfactant, a pH adjuster, and a pH buffer as an additive.

  Examples of the dispersion solvent provided with the dispersion of the present invention include alcohols such as methanol, ethanol, isopropanol, n-butanol, and methyl isocarbinol; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, isophorone, and cyclohexanone. Ketones such as N; N-dimethylformamide, amides such as N, N-dimethylacetamide; ethers such as diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, and 3,4-dihydro-2H-pyran Glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether; 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxy Glycol ether acetates such as ethyl acetate; esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, and ethylene carbonate; aromatic hydrocarbons such as benzene, toluene, xylene; hexane, heptane, isooctane, Aliphatic hydrocarbons such as cyclohexane; Halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane and chlorobenzene; Sulfoxides such as dimethyl sulfoxide; N-methyl-2-pyrrolidone, N-octyl- Organic solvents such as pyrrolidones such as 2-pyrrolidone can be used. These may be used by mixing with water.

  The concentration (solid content concentration) of the silica-based composite fine particles contained in the dispersion of the present invention is preferably in the range of 0.3 to 50% by mass.

  Although the manufacturing method of the dispersion liquid of this invention is not specifically limited, It is preferable to manufacture with the manufacturing method of this invention demonstrated below.

<Production method of the present invention>
The production method of the invention will be described.
The manufacturing method of the present invention includes step 1 and step 2 described below.

<Production method of the present invention>

<Step 1>
In step 1, silica sol in which silica fine particles are dispersed in a solvent is used as a raw material.
As the silica sol to be used, a known silica sol can be applied. For example, silica sol prepared by dispersing silica fine particles prepared from water glass as a raw material or silica fine particles synthesized using alkoxysilane as a raw material are dispersed in a solvent. Examples thereof include silica sol.

Generally, silica fine particles prepared using water glass as a raw material are Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, Zr, U and Th, Cl, derived from raw water glass. Each element or ion species of NO ₃ , SO ₄ and F is contained in a total of about several thousand ppm. When such silica fine particles are used, it is possible to reduce the content of each element or ion species by performing an ion exchange treatment after making the silica sol formed by dispersing the silica fine particles in a solvent. About several hundred ppm of each element or ionic species remains. Therefore, when silica particles using water glass as a raw material are used, impurities can be reduced by acid treatment or the like.
On the other hand, silica fine particles synthesized using alkoxysilane as a raw material usually have a content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn and Zr of 100 ppm or less. Yes, since the content of each element of U, Th, Cl, NO ₃ , SO ₄ and F is 5 ppm or less, the abrasive particles particularly applied to the field of manufacturing semiconductor devices were produced by hydrolysis of alkoxysilane. It is preferable to use a silica sol in which silica fine particles are dispersed in a solvent.
The silica-based composite fine particles according to the present invention can be suitably used for polishing applications such as semiconductor devices because the content of each element or ionic species is at a very low level.
In addition, as a silica sol in which the silica fine particles used in Step 1 are dispersed in a solvent, those having an average particle diameter of less than 350 nm are used. Usually, silica sol having an average particle diameter of 30 to 200 nm is preferably used.

  In step 1, the silica sol in which the silica fine particles as described above are dispersed in a solvent is maintained under a stirring condition at a temperature of 5 to 98 ° C. (preferably 50 to 98 ° C.) and a pH range of 7.0 to 9.0. The metal salt of is added continuously or intermittently to obtain a precursor particle dispersion containing precursor particles.

  The dispersion medium in the silica sol preferably contains water, and a water sol is preferably used.

The solid content concentration in the silica sol is preferably 1 to 40% by mass in terms of SiO ₂ . When this solid content concentration is too low, the silica concentration in the production process becomes low, and the productivity may deteriorate.

  Further, impurities can be extracted with a cation exchange resin or an anion exchange resin, a mineral acid, an organic acid, or the like, and a silica sol can be deionized using an ultrafiltration membrane or the like as necessary. Silica sol from which impurity ions and the like are removed by deionization treatment is more preferable because a hydroxide containing silicon is easily formed on the surface.

In step 1, a metal salt of cerium is continuously or intermittently added to the silica sol as described above while maintaining a temperature of 5 to 98 ° C. and a pH range of 7.0 to 9.0 under stirring conditions.
As the metal salt of cerium, cerium chloride, nitrate, sulfate, acetate, carbonate, metal alkoxide and the like can be used. Specific examples include cerium nitrate, cerium carbonate, cerium sulfate, and cerium chloride. Of these, ceric nitrate is preferred. Crystalline cerium oxides are formed from a solution that becomes supersaturated at the same time as neutralization, and they quickly adhere to the silica fine particles by an agglomeration and deposition mechanism.

  The amount of the cerium metal salt added to the silica sol is such that the ratio of silica to ceria in the obtained composite fine particles of the present invention is in the range of 100: 11 to 316 as described above.

  The temperature at the time of stirring after adding the metal salt of cerium to the silica sol is 5 to 98 ° C, preferably 50 to 95 ° C. If the temperature is too low, the reaction of mixing with a hydroxide or forming a low oxide and crystallizing is remarkably slow, which is not preferable. On the other hand, if this temperature is too high, scale and the like are easily generated on the reactor wall surface, which is not preferable.

  Moreover, it is preferable that the time at the time of stirring is 0.5 to 24 hours, and it is more preferable that it is 0.5 to 18 hours. If this time is too short, crystalline cerium oxide cannot be formed sufficiently, which is not preferable. Conversely, even if this time is too long, the formation of crystalline cerium oxide is uneconomical because the reaction does not proceed any further.

  Further, the pH range of the silica sol when a cerium metal salt is added to the silica sol and stirred is 7.0 to 9.0, but preferably 7.6 to 7.9. At this time, it is preferable to adjust the pH by adding an alkali or the like. A publicly known alkali can be used as an example of such an alkali. Specific examples include aqueous ammonia, alkali hydroxide, alkaline earth metal, and aqueous amines, but are not limited thereto.

  By such step 1, a dispersion (precursor particle dispersion) containing particles (precursor particles) that are precursors of the composite fine particles of the present invention is obtained.

  The precursor particle dispersion obtained in step 1 may be further diluted or concentrated using pure water, ion-exchanged water, or the like before being subjected to step 2, and may be subjected to the next step 2.

  In addition, it is preferable that the solid content concentration in a precursor particle dispersion is 1-27 mass%.

  If desired, the precursor particle dispersion may be deionized using a cation exchange resin, an anion exchange resin, an ultrafiltration membrane, an ion exchange membrane, or the like.

<Step 2>
In step 2, the pH of the precursor particle dispersion is adjusted to 6.0 to 7.0 , dried, and then fired at 400 to 1,200 ° C.

The method for drying is not particularly limited. It can be dried using a conventionally known dryer. Specifically, a box-type dryer, a band dryer, a spray dryer or the like can be used.
Incidentally, it shall be the 6.0-7.0 pH of the precursor particles dispersion before drying further. It is because surface activity can be suppressed when the pH of the precursor particle dispersion before drying is 6.0 to 7.0.

  After drying, the firing temperature is 400 to 1200 ° C, preferably 800 to 1100 ° C, and more preferably 1000 to 1090 ° C. When firing in such a temperature range, crystallization of ceria proceeds sufficiently, and mother particles and child particles are firmly bonded. If this temperature is too high, ceria crystals may grow abnormally, amorphous silica constituting the mother particles may crystallize, or fusion between ceria may progress.

In Step 2, the silica-based composite fine particles obtained by firing are subjected to dry crushing / pulverization and solvent dispersion, or wet-type crushing / pulverization to obtain a silica-based composite fine particle dispersion.
Conventionally known devices can be used as the dry crushing / pulverizing device, and examples thereof include an attritor, a ball mill, a vibration mill, and a vibration ball mill. Conventionally known apparatus can be used as a wet crushing / pulverizing apparatus. For example, a batch type bead mill such as a basket mill, a horizontal type, a vertical type or an annular type continuous bead mill, a sand grinder mill, a ball mill, etc. And a wet medium stirring mill (wet crusher). Examples of the beads used in the wet medium stirring mill include beads made of glass, alumina, zirconia, steel, flint stone, and the like.

  The dispersion of the present invention can be obtained by the production method of the present invention.

<Slurry for polishing>
The liquid containing the dispersion of the present invention can be preferably used as a polishing slurry (hereinafter also referred to as “the polishing slurry of the present invention”).

  The polishing slurry of the present invention is excellent in effects such as a high polishing rate when polishing a semiconductor substrate and the like, and few scratches (scratches) on the polishing surface during polishing.

  The polishing slurry of the present invention contains water and / or an organic solvent as a dispersion solvent. For example, water such as pure water, ultrapure water, or ion exchange water is preferably used as the dispersion solvent. Furthermore, the polishing slurry of the present invention may contain one or more selected from the group consisting of a polishing accelerator, a surfactant, a heterocyclic compound, a pH adjuster and a pH buffer as an additive.

<Polishing accelerator>
In the polishing slurry 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.

  Other examples of polishing accelerators include inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, oxalic acid, and hydrofluoric acid, and organic acids such as acetic acid, or ammonium salts, amine salts, and mixtures thereof. be able to. 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 slurry 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 slurry, a cationic, anionic, nonionic or amphoteric surfactant or a 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, Examples thereof include aminocarboxylates, imidazolinium betaines, lecithins, and 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 amide, polyoxyethylene alkylamide, and the like. In addition, a fluorine-type surfactant etc. are mentioned.

  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 slurry 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 slurry. It is more preferable to set it as 01-5g, and it is especially preferable to set it as 0.1-3g.

  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 slurry, 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.

<Heterocyclic compound>
For the polishing slurry of the present invention, when the substrate to be polished contains a metal, a heterocyclic compound is formed for the purpose of suppressing the erosion of the substrate to be polished by forming a passive layer or a dissolution inhibiting layer on the metal. May be included. Here, the “heterocyclic compound” is a compound having a heterocyclic ring containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom or a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. A heteroatom means only those atoms that form part of a heterocyclic ring system, either external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of are 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 slurry for polishing which concerns on this invention, it is preferable that it is 0.001-1.0 mass%, and it is more that it is 0.001-0.7 mass%. Preferably, it is 0.002-0.4 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 slurry 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 the polishing slurry is adjusted to a pH of less than 7, an acidic one is used as a pH adjuster. For example, hydroxy acids such as acetic acid, 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 slurry constant, a pH buffer may be used. Examples of pH buffering agents that can be used include phosphates and borates such as ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium tetraborate tetrahydrated water, and organic acids.

  Examples of the dispersion solvent for the polishing slurry of the present invention include alcohols such as methanol, ethanol, isopropanol, n-butanol, and methyl isocarbinol; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, isophorone, and cyclohexanone. Ketones such as N; N-dimethylformamide, amides such as N, N-dimethylacetamide; ethers such as diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, and 3,4-dihydro-2H-pyran Glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether; 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-but Glycol ether acetates such as ciethyl acetate; Esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate and ethylene carbonate; Aromatic hydrocarbons such as benzene, toluene and xylene; Hexane, heptane and isooctane Aliphatic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane, chlorobenzene; sulfoxides such as dimethyl sulfoxide; N-methyl-2-pyrrolidone, N-octyl Organic solvents such as pyrrolidones such as -2-pyrrolidone can be used. These may be used by mixing with water.

  The solid content concentration contained in the polishing slurry of the present invention is preferably in the range of 0.3 to 50 mass%. If this solid content concentration is too low, the polishing rate may decrease. Conversely, even if the solid content concentration is too high, the polishing rate is rarely improved further, which can be uneconomical.

  Hereinafter, the present invention will be described based on examples. The present invention is not limited to these examples.

First, details of each measurement method and test method in Examples and Comparative Examples will be described.
For each example and comparative example, the following measurement results and test results are shown in Table 1.

[Measurement of content of Na, etc.]
[Mother particles]
The SiO ₂ weight of the mother particles in the examples and comparative examples was determined by weighing the silica sol corresponding to the silica sol introduced in the production process of the silica composite fine particle dispersion at 150 ° C. for 1 hour, respectively. In addition, in the mother particles of Example 5 and Comparative Example 3, the SiO ₂ weight of the silica sol corresponding to the liquid A was determined by weighing after 1000 ° C. ignition loss.
Next, the contents of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, Zr, U, and Th in the mother particles of all examples and comparative examples are determined by the following method. Measured with About 10 g of each silica sol sample (solid content 20% by mass) was collected in a platinum dish, 20 ml of hydrofluoric acid and 5 ml of nitric acid were added, and the mixture was heated to dryness on a sand bath. Nitric acid (2 ml) was added to the dried product to dissolve it, poured into a 100 ml volumetric flask, and water was added to make 100 ml. In this solution, Na and K were measured with an atomic absorption spectrophotometer (manufactured by Hitachi, Ltd., Z-2310). Ag, Al, Ca, Cr, Cu, Fe, Mg, Ni, Ti, Zn, Zr, U, and Th were measured with an ICP plasma emission spectrometer (SPS5520 manufactured by SII).
The content of each anionic species was measured by the following method.
<Cl>
50 ml of water, 5 ml of acetic acid and 4 ml of 0.001 mol sodium chloride solution were added to 20 g of a sample of silica sol containing silica fine particles (mother particles) (solid content 20% by mass), and potentiometric titration with a 0.002 mol silver nitrate solution ( Analysis was carried out using a potentiometric titrator AT-610, manufactured by Kyoto Electronics.
The same processing was performed except for the sample as a blank, and the value was subtracted to obtain a measured value.
<NO ₃ , SO ₄ , F>
A 5 g sample (solid content of 20% by mass) made of silica sol containing silica fine particles (mother particles) was diluted with water to 100 ml, and centrifuged at 4000 rpm for 20 minutes in a centrifuge (HIMAC CT06E manufactured by Hitachi). The supernatant was analyzed with an ion chromatograph (ICS-1100, manufactured by DIONEX).

[Silica composite fine particles]
Ce, Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, Zr, U, Th, Cl, NO ₃ , SO ₄ of silica-based composite fine particles in Examples and Comparative Examples And the content rate of F was measured with the following method.
About 1 g (solid content 20% by mass) of each silica-based composite fine particle dispersion was collected in a platinum dish. 3 ml of phosphoric acid, 5 ml of nitric acid and 10 ml of hydrofluoric acid were added and heated on a sand bath. Once dry, a small amount of water and 50 ml of nitric acid were added and dissolved, placed in a 100 ml volumetric flask, and water was added to make 100 ml.
Na and K were measured for this solution with an atomic absorption spectrophotometer (manufactured by Hitachi, Ltd., Z-2310).
Ce, Ag, Al, Ca, Cr, Cu, Fe, Mg, Ni, Ti, Zn, Zr, U and Th were measured with an ICP plasma emission spectrometer (SPS5520 manufactured by SII). Analytical methods for Cl, NO ₃ , SO ₄ and F are as follows.
<Cl>
50 ml of water, 5 ml of acetic acid and 4 ml of a 0.001 molar sodium chloride solution were added to 20 g of a sample composed of a silica-based composite fine particle dispersion (solid content: 20% by mass), and potentiometric titration method (manufactured by Kyoto Electronics Co., Ltd.) with a 0.002 molar silver nitrate solution. Analysis was conducted with a potentiometric titrator AT-610).
The same processing was performed except for the sample as a blank, and the value was subtracted to obtain a measured value.
<NO ₃ , SO ₄ , F>
A 5 g sample (solid content: 20% by mass) composed of a silica-based composite fine particle dispersion is diluted with water to 100 ml, centrifuged at 4000 rpm for 20 minutes in a centrifuge (HIMAC CT06E manufactured by Hitachi), and the supernatant. Was analyzed with an ion chromatograph (ICS-1100, manufactured by DIONEX).
The SiO ₂ weight was determined by subtracting the Ce concentration determined above from CeO ₂ from the solid content determined by 1000 ° C. ignition loss of the silica-based composite fine particle dispersion. Then, from the obtained SiO ₂ weight and CeO ₂ weight, the mass ratio of silica and ceria in the silica-based composite fine particles was determined.

[X-ray diffraction method, measurement of crystallite diameter]
In accordance with the method described above, the silica-based composite fine particle dispersions obtained in the examples and comparative examples were dried, and the obtained powder was pulverized in a mortar for 10 minutes to obtain an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.). , RINT 1400) to obtain an X-ray diffraction pattern to identify the crystal form.
Further, as described above, the half width of the peak of the (111) plane in the vicinity of 2θ = 28 degrees in the obtained X-ray diffraction pattern was measured, and the crystallite diameter was determined by the Scherrer equation.

<Average particle size>
For the silica sol and silica-based composite fine particle dispersion obtained in the examples and comparative examples, the average particle size of the particles contained therein was measured by the method described above. Specifically, PAR-III manufactured by Otsuka Electronics Co., Ltd. was used as the silica mother particle, and a Microtrac UPA apparatus manufactured by Nikkiso Co., Ltd. was used as the silica composite fine particle.

<Short diameter / Long diameter ratio>
About each particle | grains which the silica sol and silica type composite fine particle dispersion liquid which were obtained in the Example and the comparative example contain, a transmission electron microscope (Transmission Electron Microscope; Hitachi Ltd. make, model number "S-5500" Hitachi Ltd. make, model number: In a photographic projection obtained by taking a photograph at a magnification of 250,000 times (or 500,000 times) using S-5500, the maximum diameter of the particles is taken as the major axis, the length is measured, and the value is taken as the major diameter ( In addition, a point that bisects the major axis on the major axis is determined, two points where a straight line perpendicular to the major axis intersects the outer edge of the particle are obtained, and the distance between the two points is measured to determine the minor axis ( The ratio (DS / DL) was determined, and this measurement was performed on any 50 particles, and the number ratio (%) of particles having a minor axis / major axis ratio of 0.8 or less was obtained. .

[Polishing test method]
A slurry (polishing slurry) containing the silica-based composite fine particle dispersion obtained in each of Examples and Comparative Examples was prepared. Here, the solid content concentration was 9% by mass.
Next, an aluminosilicate glass substrate for a hard disk was prepared as a substrate to be polished. This substrate has a donut shape, an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 0.635 mm. This substrate was pre-polished and had a surface roughness (Ra) of 0.3 nm.
Next, the substrate to be polished is set in a polishing apparatus (NF300, manufactured by Nano Factor Co., Ltd.), and a polishing pad (“Polytex φ12” manufactured by Nitta Haas) is used, with a substrate load of 0.18 MPa and a table rotation speed of 30 rpm. Polishing was performed by supplying the polishing slurry at a rate of 20 ml / min for 10 minutes.
And the grinding | polishing speed | rate was calculated by calculating | requiring the weight change of the to-be-polished base material before and behind grinding | polishing.
Moreover, the smoothness (surface roughness Ra) of the surface of the polishing substrate was measured using an atomic force microscope (AFM, manufactured by Hitachi High-Tech Science Co., Ltd.).
For measurement of scratches (line marks), an aluminum disk substrate was set in a polishing apparatus (NF300, manufactured by Nano Factor Co., Ltd.), and a polishing pad (“Polytex φ12” manufactured by Nitta Haas) was used. Polishing is performed by supplying polishing slurry at a rate of 20 ml / min for 5 minutes at a table rotation speed of 30 MPa at .05 MPa, using an ultra-fine defect / visualization macro apparatus (product name: Micro-MAX) manufactured by VISION PSYTEC. The entire surface was observed with Zoom 15, and the number of scratches (linear traces) present on the polished substrate surface corresponding to 65.97 cm ² was counted and totaled, and evaluated according to the following criteria.
Number of linear marks Evaluation Less than 80
80 or more "Many"
At least 80 and so many that the total number cannot be counted

<Example 1>
"Silica sol (60 nm)" were mixed and prepared ethanol 12,090g and ethyl orthosilicate 6,363.9g of was a mixture a _1.
Next, 6,120 g of ultrapure water and 444.9 g of 29% ammonia water were mixed to obtain a mixed solution b ₁ .
Next, 192.9 g of ultrapure water and 444.9 g of ethanol were mixed and used as bedding water.
Then, the stirring water was adjusted to 75 ° C. while stirring, and the mixed solution a ₁ and the mixed solution b ₁ were simultaneously added so that the addition was completed in 10 hours each. When the addition is completed, the liquid temperature is kept at 75 ° C. for 3 hours and ripened, then the solid content concentration is adjusted, and the SiO ₂ solid content concentration is 19% by mass. Laser diffraction / scattering method PAR- manufactured by Otsuka Electronics Co., Ltd. 9,646.3 g of silica sol having an average particle diameter of 60 nm measured by III was obtained.

"Silica sol (average particle size 108 nm)" was mixed with the preparation of methanol 2,733.3g of the ethyl orthosilicate 1,822.2G, was mixed solution a _2.
Next, 1,860.7 g of ultrapure water and 40.6 g of 29% ammonia water were mixed to obtain a mixed solution b ₂ .
Next, 592.1 g of ultrapure water and 1,208.9 g of methanol were mixed and used as a covering water, and 922.1 g of silica sol having an average particle diameter of 60 nm obtained in the previous step was added.
Then, the water containing the silica sol was adjusted to 65 ° C. while stirring, and the mixed solution a ₂ and the mixed solution b ₂ were simultaneously added so that the addition was completed in 18 hours. When the addition was completed, the liquid temperature was kept at 65 ° C. for 3 hours for aging, and then the solid content concentration (SiO ₂ solid content concentration) was adjusted to 19% by mass to obtain 3,600 g of high-purity silica sol. .
The particles contained in the high-purity silica sol had an average particle diameter of 108 nm as measured by PAR-III manufactured by Otsuka Electronics Co., Ltd.
Further, the content of alkali metals, alkaline earth metals, and the like by ICP measurement was 1 ppm or less. Table 1 shows the analysis results of various elements or ionic species contained in the mother particles. (The following examples and comparative examples are also the same)

Next, 114 g of cation exchange SK-1BH (manufactured by Mitsubishi Chemical Corporation) was gradually added to 1,053 g of this high-purity silica sol and stirred for 30 minutes to separate the resin. The pH at this time was 5.1.
Ultrapure water was added to the obtained silica sol to obtain 6,000 g of Liquid A having a SiO ₂ solid content concentration of 3% by mass. (Hereinafter, in the manufacturing process of the silica-based composite fine particle dispersion, the silica sol to be added to the B liquid described later is referred to as “A liquid”.)

Next, ion-exchanged water was added to cerium (III) nitrate hexahydrate (manufactured by Kanto Chemical Co., Inc., 4N high-purity reagent) to obtain 2.5 mass% B liquid in terms of CeO ₂ . (Hereinafter, the cerium metal salt dispersion is referred to as “Liquid B”.)

Next, the liquid A (6,000 g) was heated to 50 ° C. and stirred, while the liquid B (8,453 g, 100 parts by mass of SiO _{2) was} equivalent to 117.4 parts by mass of CeO _2. Was added over 18 hours. During this time, the liquid temperature was maintained at 50 ° C., and 3% ammonia water was added as necessary to maintain pH 7.85.
And when addition of B liquid was complete | finished, the liquid temperature was raised to 93 degreeC and ageing | curing | ripening was performed for 4 hours. After aging, the product was allowed to cool by allowing it to stand indoors, and after cooling to room temperature, washing was performed while supplying ion-exchanged water with an outer membrane. The precursor particle dispersion obtained after the washing was finished had a solid content concentration of 7% by mass, a pH of 9.1 (at 25 ° C.), and an electric conductivity of 67 μs / cm (at 25 ° C.). .

  Next, 5% by mass acetic acid was added to the obtained precursor particle dispersion to adjust the pH to 6.5, followed by drying in a 120 ° C. dryer for 16 hours, and then using a 1090 ° C. muffle furnace. Firing was performed for 2 hours to obtain a powder.

  After adding 375 g of ion-exchanged water to 125 g of the obtained powder and further adjusting the pH to 9 using a 3% aqueous ammonia solution, it was wetted with high-purity silica beads of φ0.22 mm (manufactured by Daiken Chemical Co., Ltd.). Crushing and pulverization were performed to obtain 540 g of a silica-based composite fine particle dispersion having a solid content concentration of 20% by mass.

  Table 1 shows the analysis results (content ratios) of various elements or ion species for the silica-based composite particles contained in the obtained silica-based composite particle dispersion. (The following examples and comparative examples are also the same)

  When the silica-based composite fine particles contained in the obtained silica-based composite fine particle dispersion were measured by an X-ray diffraction method, a Ceriaite diffraction pattern was observed.

Next, the silica-based composite fine particle dispersion was concentrated with a rotary evaporator, then diluted with ion-exchanged water to adjust the concentration, to obtain a 9% by mass polishing slurry, and a polishing test was performed. Moreover, the minor axis / major axis ratio of the silica-based composite fine particles contained in the polishing slurry was measured. The results are shown in Table 1.
Further, the average particle size of the silica-based composite fine particles was measured using a dynamic light scattering measurement device, Microtrack UPA, manufactured by Nikkiso Co., Ltd. The results are shown in Table 1.

Further, the silica-based composite fine particles contained in the silica-based composite fine particle dispersion obtained in Example 1 were observed using SEM and TEM. An SEM image and a TEM image (100,000 times) are shown in FIGS.
Further, FIG. 1C shows a transmission electron microscope image (300,000 times) obtained by measuring the particle diameter of the child particles.

  Furthermore, FIG. 2 shows an X-ray diffraction pattern of the silica-based composite fine particles contained in the silica-based composite fine particle dispersion obtained in Example 1.

In the X-ray diffraction pattern of FIG. 2, it is a fairly sharp Ceriaite crystal, and it appears that ceria crystal particles are strongly sintered with the silica surface from TEM and SEM images.
Further, from FIG. 1, it is observed that the surface of the silica particles is covered with a thin film.

<Example 2>
In Example 1, the condition of the addition amount of the B solution was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). In Example 2, the addition amount of the B solution was The other conditions were the same as those in Example 1 and the same measurements were performed, with 2153 g, 100 parts by mass of SiO ₂ and CeO ₂ equivalent to 29.9 parts by mass). .
The results are shown in Table 1.

<Example 3>
In Example 1, the condition of the addition amount of the B liquid was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). The above conditions were 1,080 g, and CeO ₂ was equivalent to 15 parts by mass with respect to 100 parts by mass of SiO _2. The other operations were performed in the same manner as in Example 1, and the same measurements were performed.
The results are shown in Table 1.

<Example 4>
"Variant silica sol (average particle size 35 nm)" was mixed with the preparation of ethanol 7,100g of the ethyl orthosilicate 3,742G, was mixed solution a _2.
Next, 1,060 g of ultrapure water and 128 g of 29% ammonia water were mixed to obtain a mixed solution b ₂ .
Next, 1,868 g of ethanol was used as water.
Then, the stirring water was adjusted to 75 ° C. while stirring, and the mixed solution a ₂ and the mixed solution b ₂ were added simultaneously so that the addition was completed in 6 hours each. After the addition was completed, the liquid temperature was kept at 75 ° C. for 3 hours and ripened, then the solid content concentration was adjusted, and the average of SiO ₂ solid content concentration 19% by mass, measured by PAR-III manufactured by Otsuka Electronics Co., Ltd. 5,400 g of silica sol having a particle diameter of 35 nm was obtained.
Ultrapure water was added to the obtained irregular shaped silica sol to obtain a liquid A having a SiO ₂ solid content concentration of 3% by mass.

Next, the condition for the addition amount of the liquid B is 2,398 g (corresponding to 33.3 parts by mass of CeO ₂ with respect to 100 parts by mass of SiO ₂ ), and other conditions are the same as those in Example 1. A silica-based composite particle dispersion containing silica-ceria composite oxide was prepared. And operation similar to Example 1 was performed and the same measurement was performed. The results are shown in Table 1.

<Example 5>
<Preparation of High-Purity Silicic Acid Solution> An aqueous sodium silicate solution having an SiO ₂ concentration of 24.06% by mass and an Na ₂ O concentration of 7.97% by mass was prepared. Then, pure water was added so that SiO ₂ concentration of 5.0 wt% to the aqueous solution of sodium silicate.

[Acid silicic acid solution]
18 kg of the obtained 5.0 mass% sodium silicate aqueous solution was passed through 6 L of strongly acidic cation exchange resin (SK1BH, manufactured by Mitsubishi Chemical Corporation) at a space velocity of 3.0 h ⁻¹ , and the pH was 2.7. 18 kg of acidic silicic acid solution was obtained.
The obtained acidic silicic acid solution had a SiO ₂ concentration of 4.7% by mass.

[High purity silicic acid solution]
Next, the acidic silicic acid solution was passed through a strongly acidic cation exchange resin (SK1BH, manufactured by Mitsubishi Chemical Corporation) at a space velocity of 3.0 h ⁻¹ to obtain a high purity silicic acid solution having a pH of 2.7. The high-purity silicic acid solution obtained had a SiO ₂ concentration of 4.4% by mass.

<Preparation of silica sol (average particle size 25 nm)> While stirring a high-purity silicic acid solution in 42 g of pure water, 514.5 g was added, and then 1558% ammonia water was added in 1,584.6 g. And held for 30 minutes.
Next, 13,700 g of high-purity silicic acid solution was added over 18 hours, and after completion of the addition, aging was carried out while maintaining 83 ° C. to obtain a silica sol having an average particle diameter of 25 nm.
The obtained silica sol was cooled to 40 ° C., and the SiO ₂ concentration was concentrated to 12% with an ultrafiltration membrane (SIP1013 manufactured by Asahi Kasei).

Preparation of << Silica Sol (Average Particle Diameter 45 nm) 963 g of 12% 25 nm silica sol was added to 991 g of pure water with stirring. Next, 1,414 g of 15% aqueous ammonia was added, and then the temperature was raised to 87 ° C. and held for 30 minutes.
Next, 12,812 g of high-purity silicic acid solution was added over 18 hours, and after completion of the addition, aging was performed while maintaining 87 ° C. to obtain a silica sol having an average particle diameter of 45 nm.
The obtained silica sol was cooled to 40 ° C., and the SiO ₂ concentration was concentrated to 12% with an ultrafiltration membrane (SIP1013 manufactured by Asahi Kasei).

Preparation of << Silica Sol (Average Particle Diameter 70nm) 705g of 12% average particle diameter 45nm silica sol was added to 705g of pure water with stirring. Next, 50 g of 15% aqueous ammonia was added, and then the temperature was raised to 87 ° C. and held for 30 minutes.
Next, 7,168 g of high-purity silicic acid solution was added over 18 hours, and after completion of the addition, aging was carried out while maintaining 87 ° C. to obtain a silica sol having an average particle diameter of 70 nm.
The obtained silica sol was cooled to 40 ° C., and the SiO ₂ concentration was concentrated to 12% with an ultrafiltration membrane (SIP1013 manufactured by Asahi Kasei).

Preparation of <Silica sol (96 nm)> 1081 g of silica sol having an average particle diameter of 70% by mass of 12% by mass was added to 1,081 g of pure water. Next, 50 g of 15% aqueous ammonia was added, and then the temperature was raised to 87 ° C. and held for 30 minutes.
Next, 6,143 g of high-purity silicic acid solution was added over 18 hours, and after completion of the addition, aging was performed while maintaining 87 ° C., and a silica sol having an average particle size of 96 nm was obtained with PAR-III manufactured by Otsuka Electronics Co., Ltd.
The obtained silica sol was cooled to 40 ° C., and the SiO ₂ concentration was concentrated to 12% with an ultrafiltration membrane (SIP1013 manufactured by Asahi Kasei). Anion exchange resin SANUP B manufactured by Mitsubishi Chemical Corporation was added to the silica sol after concentration to remove anions.
Ultrapure water was added to the obtained silica sol to obtain a liquid A having a SiO ₂ solid content concentration of 3% by mass.
The condition of the addition amount of the liquid B is 8,453 g (CeO ₂ is equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ), and the other conditions are the same as those in Example 1, and silica ceria. A silica-based composite particle dispersion containing a composite oxide was prepared. And operation similar to Example 1 was performed and the same measurement was performed. The results are shown in Table 1.

  Further, the silica-based composite fine particle dispersion obtained in Example 5 was observed using SEM and TEM. An SEM image and a TEM image (100,000 times) are shown in FIGS.

  Furthermore, the X-ray diffraction pattern of the silica-based composite fine particles contained in the silica-based composite fine particle dispersion obtained in Example 5 is shown in FIG.

  From the SEM images and TEM images of FIGS. 3A and 3B and the X-ray diffraction peak of FIG. In addition, the particles of Example 5 are slightly higher in Na than the particles of Example 1 because sodium silicate is used as a raw material. For this reason, the silica-based composite fine particles must be fired at a slightly lower temperature. Since it tends to be too large, it was carried out at 1,070 ° C.

<Example 6>
In Example 1, the condition of the addition amount of B liquid was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). In Example 7, the addition amount of B liquid was 14400 g, with respect to 100 parts by mass of SiO ₂ , CeO ₂ corresponds to 200 parts by mass), and other operations were performed in the same manner as in Example 1 and the same measurements were performed.
The results are shown in Table 1.

<Example 7>
In Example 1, the condition of the addition amount of B liquid was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). In Example 7, the addition amount of B liquid was The condition was 18000 g, and CeO ₂ was equivalent to 250 parts by mass with respect to 100 parts by mass of SiO ₂ .
The results are shown in Table 1.

<Comparative Example 1>
A polishing test was performed on the base particles obtained in Example 1 (that is, base particles having an average particle diameter of 108 nm using alkoxysilane as a raw material were treated as silica-based composite fine particles).
The results are shown in Table 1.

<Comparative Example 2>
A polishing test was carried out on the mother particles obtained in Example 4 (that is, irregularly shaped silica mother particles having an average particle diameter of 35 nm using alkoxysilane as a raw material were treated as silica-based composite fine particles).
The results are shown in Table 1.

<Comparative Example 3>
A polishing test was performed on the base particles obtained in Example 5 (that is, base particles having an average particle diameter of 96 nm made from water glass as a raw material were treated as silica-based composite fine particles).
The results are shown in Table 1.

<Comparative Example 4>
In Example 1, the condition of the addition amount of the B solution was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). In Comparative Example 4, the addition amount of the B solution was These conditions were 360 g, and CeO ₂ was equivalent to 5 parts by mass with respect to 100 parts by mass of SiO _2. The other operations were performed in the same manner as in Example 1. However, since the particles grew abnormally, wet pulverization was difficult and the yield was considerably poor. The results are shown in Table 1.

  Further, the silica composite fine particle dispersion obtained in Comparative Example 4 was observed using SEM and TEM. An SEM image and a TEM image (100,000 times) are shown in FIGS.

  Furthermore, the X-ray diffraction pattern of the silica-based composite fine particles contained in the silica-based composite fine particle dispersion obtained in Comparative Example 4 is shown in FIG.

5 (a) and 5 (b), the particles of Comparative Example 4 lose their original spherical particle shape and become large irregularly shaped particles.
This is presumably because the amount of ceria to be coated is small and the mother particles are likely to be fused together.

  In addition to the cerium oxide crystals, Cristobalite is generated from the X-ray diffraction of FIG. 6, and this also has a small amount of ceria to be coated, so that the mother particles are likely to be fused with each other. Is considered to have crystallized.

<Comparative Example 5>
In Example 1, the condition of the addition amount of the B solution was 8,453 g (CeO ₂ was equivalent to 117.4 parts by mass with respect to 100 parts by mass of SiO ₂ ). In Comparative Example 5, the addition amount of the B solution was The conditions were 28801 g, and CeO ₂ was equivalent to 400 parts by mass with respect to 100 parts by mass of SiO _2. The other operations were performed in the same manner as in Example 1.

  Since the composite particle of the present invention does not contain impurities, it can be preferably used for polishing the surface of a semiconductor device such as a semiconductor substrate or a wiring substrate.

Claims (5)

Child particles mainly composed of crystalline ceria are bonded to the surface of mother particles mainly composed of amorphous silica, and have an average particle diameter of 50 to 350 nm having the following features [1] to [4] A silica-based composite fine particle dispersion containing silica-based composite fine particles.
[1] The silica-based composite fine particles have a mass ratio of silica and ceria of 100: 11 to 316.
[2] When the silica-based composite fine particles are subjected to X-ray diffraction, only the ceria crystal phase is detected.
[3] When the silica-based composite fine particles are subjected to X-ray diffraction, the crystallite diameter of the (111) plane of the crystalline ceria is 10 to 25 nm.
[4] The silica composite fine particles have a ratio of the number of particles having a minor axis / major axis ratio of 0.8 or less as measured by an image analysis method of 50% or more. The silica-based composite fine particles have Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr element contents of 100 ppm or less, and U, Th, Cl 2. The silica-based composite fine particle dispersion according to claim 1, wherein the contents of NO ₃ , SO ₄ and F are each 5 ppm or less.   A polishing slurry comprising the silica-based composite fine particle dispersion according to claim 1. A method for producing a silica-based composite fine particle dispersion, comprising the following step 1 and step 2.
Step 1: A silica sol in which silica fine particles are dispersed in a solvent is continuously or intermittently maintained while stirring at a temperature of 5 to 98 ° C. and a pH range of 7.0 to 9.0. Adding to obtain a precursor particle dispersion containing the precursor particles.
Step 2: After the pH of the precursor particle dispersion is adjusted to 6.0 to 7.0, the precursor particle dispersion is dried and fired at 400 to 1,200 ° C., and then subjected to dry crushing / pulverization and solvent dispersion. The process of obtaining the silica type composite fine particle dispersion of Claim 1 by performing or performing crushing and grinding | pulverization by wet. As the silica sol of step 1, the content of each element of Na, Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Ni, Ti, Zn, and Zr is 100 ppm or less, and U, Th, Cl The method for producing a silica-based composite fine particle dispersion according to claim 4, wherein a silica sol in which silica fine particles each containing 5 ppm or less of NO ₃ , SO ₄ and F are dispersed in a solvent is used.