JP2019127405A - Ceria-based composite hollow microparticle dispersion, production method thereof, and polishing abrasive grain dispersion comprising ceria-based composite hollow microparticle dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silica-based composite particle dispersion liquid capable of polishing a silica film, a Si wafer or a difficult-to-process material at a high speed and at the same time achieving high surface accuracy. SOLUTION: A ceria-based composite hollow fine particle dispersion liquid containing ceria-based composite hollow fine particles having an average particle diameter of 20 to 400 nm having the following characteristics [1] to [3]. [1] The ceria-based composite hollow fine particles have a hollow structure having voids inside the cerium-containing silica layer as an outer shell, and child particles containing crystalline ceria as a main component are dispersed inside the cerium-containing silica layer. ing. [2] In the ceria-based composite hollow fine particles, only the crystal phase of ceria is detected by X-ray diffraction. [3] The ceria-based composite hollow fine particles are measured by X-ray diffraction, and the average crystallite diameter of the crystalline ceria is 8 to 25 nm. [Selection diagram] Fig. 1

Description

  The present invention relates to a ceria-based composite hollow particle dispersion suitable as a polishing agent used for semiconductor device production and the like, and in particular, a chemical mechanical polishing (chemical mechanical polishing: CMP) is performed on a film to be polished formed on a substrate. The present invention relates to a ceria-based composite hollow fine particle dispersion for flattening, a method for producing the same, and a polishing abrasive dispersion containing the ceria-based composite hollow fine particle dispersion.

  Semiconductor devices such as semiconductor substrates and wiring boards achieve high performance through high density and miniaturization. In this semiconductor manufacturing process, so-called chemical mechanical polishing (CMP) is applied. Specifically, this technology is indispensable for shallow trench isolation, planarization of interlayer insulating films, formation of contact plugs and Cu damascene wiring, etc. It has become.

In general, an abrasive for CMP comprises abrasive grains and a chemical component, and the chemical component plays a role of promoting polishing by oxidizing or corroding a target film. On the other hand, abrasive grains have a role of polishing by mechanical action, and colloidal silica, fumed silica and ceria particles are used as abrasive grains. In particular, ceria particles are applied to polishing in a shallow trench isolation process because they exhibit a specifically high polishing rate to a silicon oxide film.
In the shallow trench isolation process, not only the polishing of the silicon oxide film but also the polishing of the silicon nitride film is performed. In order to facilitate element isolation, it is desirable that the polishing rate of the silicon oxide film is high and the polishing rate of the silicon nitride film is low, and this polishing rate ratio (selection ratio) is also important.

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 is done.
Conventionally, for example, the following method has been proposed as an abrasive used for secondary polishing as such final polishing.

  For example, in Patent Document 1, an aqueous solution of cerous nitrate and a base are stirred and mixed in an amount ratio such that the pH is 5 to 10, followed by rapid heating to 70 to 100 ° C., and aging at that temperature A method for producing cerium oxide ultrafine particles (average particle size of 10 to 80 nm) composed of a single crystal of cerium oxide characterized by the following is described. Further, according to this production method, the particle size is highly uniform and the particle shape It is described that ultrafine cerium oxide particles can be provided.

  Non-Patent Document 1 discloses a method for producing ceria-coated silica including a production process similar to the method for producing cerium oxide ultrafine particles described in Patent Literature 1. The method for producing ceria-coated silica does not have a firing-dispersion step as included in the production method described in Patent Document 1.

  Further, in Patent Document 2, at least one selected from zirconium, titanium, iron, manganese, zinc, cerium, yttrium, calcium, magnesium, fluorine, lanthanum, and strontium is used on the surface of the amorphous silica particle A. A silica-based composite particle characterized in 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 containing 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. The sintering of the particles is suppressed at the time of firing, the dispersibility in the polishing slurry can be improved, and the use amount of cerium oxide is further reduced. It is described that since it is possible, it is possible to provide an inexpensive abrasive material with high polishing performance. Further, it is described that those having an amorphous oxide layer C between the silica-based particles A and the oxide layer B are particularly excellent in the effect of suppressing the sintering of particles and the effect of improving the polishing rate.

  Furthermore, in Patent Document 3, a silica coating layer is formed on a composite oxide core fine particle having an average particle diameter of 19 to 70 nm composed of silica and an inorganic oxide other than silica so as to have a thickness of 1 to 10 nm. When inorganic silica other than silica is removed to produce silica-based hollow particles having an average particle diameter (Dn) in the range of 20 to 80 nm and a refractive index in the range of 1.10 to 1.40, By adjusting the method, the silica-based hollow fine particles are adjusted so that the particle diameter variation coefficient is in the range of 1 to 50%, and then the obtained silica-based hollow fine particles, the matrix-forming component and the polar solvent are mixed. A method for producing a coating material for forming a transparent film is described. And, according to such a manufacturing method, the adhesion between the substrate and the transparent film is high, the upper surface of the transparent film has small unevenness and becomes smooth, and therefore, the strength and the scratch resistance are excellent, and the low refractive index It is described that a transparent film excellent in antireflection performance can be formed.

Patent No. 2,746,861 JP, 2013-119131, A JP, 2014-58683, A

Seung-Ho Lee, Zhenyu Lu, S. V. Babu and Egon Matijevic, "Chemical mechanical polishing of thermal oxide films using silica particles coated with ceria", Journal of Materials Research, Volume 17, Issue 10, 2002, pp 2744-2749

However, when the present inventors actually manufactured and examined the cerium oxide ultrafine particles described in Patent Document 1, the polishing rate was low, and furthermore, defects (deterioration in surface accuracy, scratch increase, and the like) on the surface of the polishing substrate. It has been found that the remaining of the abrasive on the surface of the abrasive substrate is likely to occur.
This is because the method for producing cerium oxide ultrafine particles described in Patent Document 1 does not include the firing step, as compared to the method for producing ceria particles including the firing step (the crystallization degree of the ceria particles is increased by firing), and the liquid phase Since the cerium oxide particles are only crystallized from (an aqueous solution containing cerous nitrate), the degree of crystallization of the produced cerium oxide particles is relatively low, and the cerium oxide does not undergo calcination treatment, so the cerium oxide is solid with the base particles The inventor presumes that the main factor is that cerium oxide does not adhere and remains on the surface of the polishing substrate.

  In addition, since ceria-coated silica described in Non-Patent Document 1 is not fired, it is considered that the actual polishing rate is low, and because it is not fixed and integrated with the silica particles, it easily falls off and the polishing rate decreases. Also, the stability of the polishing is lost, and the retention of particles on the surface of the polishing substrate is also a concern.

Furthermore, when polishing is performed using the silica-based composite particles of the embodiment having the oxide layer C described in Patent Document 2, impurities such as aluminum may remain on the surface of the semiconductor device, which may adversely affect the semiconductor device. The inventor found out.
Further, the ceria particles described in these documents are attached on the base particle and are not firmly fixed, so they are easily detached from the base particle.
Further, when polishing is performed using abrasive grains in which crystalline ceria particles are formed on true spherical silica mother particles described in Patent Document 2, the silica film is caused by a chemical reaction that occurs simultaneously with the mechanical action during polishing of the ceria particles. Although the polishing rate is high, under high pressure conditions, the contact area between the substrate and the ceria may be reduced due to the ceria crystal falling off, abrasion, or collapse, and the polishing rate may be reduced.

  The present invention aims to solve the above-mentioned problems. That is, the present invention can polish a silica film, a Si wafer or a difficult-to-process material at high speed, and at the same time has high surface accuracy (low scratch, little abrasive grains remaining on the substrate, and improved substrate Ra value. Etc.) and can be preferably used for polishing the surface of a semiconductor device such as a semiconductor substrate or a wiring substrate, and a manufacturing method thereof and a ceria-based composite hollow fine particle dispersion. An object is to provide a polishing abrasive dispersion containing a liquid.

The inventor has intensively studied to solve the above-mentioned problems, and has completed the present invention.
The present invention is the following (1) to (6).
(1) A ceria-based composite hollow fine particle dispersion containing ceria-based composite hollow fine particles having an average particle diameter of 20 to 400 nm having the following features [1] to [3].
[1] The ceria-based composite hollow particle has a hollow structure having a void in the inside of the cerium-containing silica layer as the outer shell, and child particles mainly composed of crystalline ceria are dispersed in the inside of the cerium-containing silica layer. Being
[2] The ceria-based composite hollow particles should be detected only in the crystalline phase of ceria when subjected to X-ray diffraction.
[3] The ceria-based composite hollow fine particles have an average crystallite diameter of the crystalline ceria of 8 to 30 nm measured by X-ray diffraction.
(2) The ceria-based composite as described in (1) or (2) above, wherein the content ratio of impurities contained in the ceria-based composite hollow fine particles is as shown in the following (a) and (b): Hollow particle dispersion.
(A) The contents of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr are each 100 ppm or less.
(B) The contents of U, Th, Cl and SO ₄ are each 5 ppm or less.
(3) A polishing abrasive particle dispersion containing the ceria-based composite hollow particle dispersion according to (1) or (2) above.
(4) The polishing abrasive dispersion according to (3) above, wherein the polishing abrasive dispersion is for planarizing a semiconductor substrate on which a silica film is formed.
(5) A method for producing a ceria-based composite hollow fine particle dispersion, comprising the following steps 1 to 3, wherein the ceria-based composite hollow fine particle dispersion described in (1) or (2) is obtained.
Step 1: A silica hollow fine particle dispersion in which silica fine particles are dispersed in a solvent is stirred, and the temperature is maintained at 0 to 70 ° C., the pH is set to 7.0 to 11.0, and the oxidation-reduction potential is maintained at −400 to 300 mV. Meanwhile, a step of adding a metal salt of cerium continuously or intermittently to obtain a precursor particle dispersion containing precursor particles.
Step 2: The precursor particle dispersion is dried, calcined at 400 to 1,200 ° C., a solvent is added to the obtained calcined product, and wet crushing is performed in a pH range of 8.6 to 10.8. And a step of obtaining a fired body disintegration dispersion.
Step 3: A step of obtaining a ceria-based composite hollow fine particle dispersion by subjecting the calcined dispersion to a centrifuge at a relative centrifugal acceleration of 300 G or more and subsequently removing a sediment component.
(6) The content ratio of the impurities contained in the silica hollow fine particles in the step 1 is as shown in the following (a) and (b): Method of producing a dispersion.
(A) The contents of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr are each 100 ppm or less.
(B) The contents of U, Th, Cl and SO ₄ are each 5 ppm or less.

When the ceria-based composite hollow particle dispersion of the present invention is used, for example, as an abrasive particle dispersion for polishing, polishing is performed at high speed even if the target is a difficult-to-process material including silica film, Si wafer, etc. At the same time, high surface precision (low scratch, low surface roughness (Ra) of the substrate to be polished, etc.) can be achieved. The method for producing a ceria-based composite hollow fine particle dispersion of the present invention provides a method for efficiently producing a ceria-based composite hollow fine particle dispersion exhibiting such excellent performance.
In the method for producing a ceria-based composite hollow fine particle dispersion according to the present invention, impurities contained in the ceria-based composite hollow fine particles can be remarkably reduced and highly purified. The highly purified ceria-based composite hollow particle dispersion obtained by the preferred embodiment of the method for producing a ceria-based composite hollow particle dispersion according to the present invention does not contain any impurities, so that it can be used for semiconductor devices such as semiconductor substrates and wiring substrates. It can be preferably used for polishing the surface.
The ceria-based composite hollow particle dispersion of the present invention is effective for flattening the surface of a semiconductor device when it is used as an abrasive dispersion for polishing, and is particularly suitable for polishing a substrate on which a silica insulating film is formed. It is.
The ceria-based composite hollow particles dispersed in the ceria-based composite hollow particle dispersion of the present invention have a hollow structure having voids inside the cerium-containing silica layer as the outer shell, and the cerium-containing silica layer In the inside of the particles, particles consisting mainly of crystalline ceria are dispersed, and the catalyst for exhaust gas purification which is an effect unique to ceria, catalyst for ammonia purification, stabilizer of other catalyst metals such as Pd, etc. The density is low compared to ceria single particles with the same outer diameter because they have a hollow structure with voids inside the cerium-containing silica layer as the outer shell, and the amount of ceria is smaller. Even if there is, it becomes possible to exhibit the same or more equivalent catalytic functions.

It is a schematic diagram of the cross section of the composite particle of this invention. It is another schematic diagram of the cross section of the composite particle of this invention. FIG. 5 is still another schematic view of the cross section of the composite particle of the present invention. 4A is an SEM image of the ceria-based composite hollow fine particles of Example 1, and FIG. 4B is a TEM image of the ceria-based composite hollow fine particles of Example 1. 1 is an X-ray diffraction pattern of Example 1; 7 is an X-ray diffraction pattern of Example 2; 7 is an X-ray diffraction pattern of Example 3.

The present invention will be described.
The present invention is a ceria-based composite hollow fine particle dispersion containing ceria-based composite hollow fine particles having an average particle size of 20 to 400 nm and having the following characteristics [1] to [3].
[1] The ceria-based composite hollow particle has a hollow structure having a void in the inside of the cerium-containing silica layer as the outer shell, and child particles mainly composed of crystalline ceria are dispersed in the inside of the cerium-containing silica layer. Being
[2] The ceria-based composite hollow particles should be detected only in the crystalline phase of ceria when subjected to X-ray diffraction.
[3] The ceria-based composite hollow fine particles have an average crystallite diameter of the crystalline ceria of 8 to 30 nm measured by X-ray diffraction.

The ceria-based composite hollow fine particles having an average particle diameter of 20 to 400 nm having the features of the above [1] to [3] are hereinafter also referred to as “the composite fine particles of the present invention”.
Further, such a ceria-based composite hollow fine particle dispersion is also referred to as “the dispersion of the present invention” below.

Moreover, this invention is the manufacturing method of the ceria type | system | group composite hollow microparticle dispersion liquid characterized by including the following process 1-process 3 and obtaining the dispersion liquid of this invention.
Step 1: A silica hollow fine particle dispersion in which silica fine particles are dispersed in a solvent is stirred, and the temperature is maintained at 0 to 70 ° C., the pH is set to 7.0 to 11.0, and the oxidation-reduction potential is maintained at −400 to 300 mV. Meanwhile, a step of adding a metal salt of cerium continuously or intermittently to obtain a precursor particle dispersion containing precursor particles.
Step 2: The precursor particle dispersion is dried, calcined at 400 to 1,200 ° C., a solvent is added to the obtained calcined product, and wet crushing is performed in a pH range of 8.6 to 10.8. And a step of obtaining a fired body disintegration dispersion.
Step 3: A step of obtaining a ceria-based composite hollow fine particle dispersion by subjecting the calcined dispersion to a centrifuge at a relative centrifugal acceleration of 300 G or more and subsequently removing a sediment component.
The relative centrifugal acceleration is expressed as a ratio of the earth's gravitational acceleration as 1G.
Such a manufacturing method is hereinafter also referred to as "the manufacturing method of the present invention".

  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.

<Structure / Mechanism>
The present invention relates to the formation process of the composite fine particles of the present invention and the mechanism for providing the hollow structure as a result, and the mechanism for the crystalline ceria particles to be dispersed and present inside the cerium-containing silica layer as the outer shell. The person estimates as follows. This will be described with reference to FIG.
For example, when an alkali is added in parallel while adding a solution of a cerium salt to a hollow silica sol obtained by performing the procedure of the method for producing silica hollow fine particles described in Patent Document 3, the solution of a cerium salt becomes Neutralized. Then, the silanol groups on the surface of the hollow silica particles react with a product (such as cerium hydroxide) by neutralization of the solution of the cerium salt (see FIG. 1 (a)), for example, Ce (OH). A layer containing CeO ₂ · SiO ₂ · SiOH etc. and CeO ₂ ultrafine particles (particle diameter in the range of 2.5 nm or more and less than 8 nm) on the surface of the hollow silica particles via a Si (OH) -like compound Also referred to as “CeO ₂ ultrafine particle-containing layer”, a layer consisting of CeO ₂ ultrafine particles and a cerium silicate layer is formed on the outside of the silica hollow fine particles (see FIG. 1 (b)). In the CeO ₂ ultrafine particles formed on the surface of the hollow silica fine particles, cerium atoms separated from the cerium silicate layer in the firing step are deposited on the CeO ₂ ultrafine particles, and ceria particles grow. In order to achieve the crystal size (8 to 30 nm) of ceria particles for achieving the required polishing rate, higher temperature baking is required if the crystallite diameter obtained in the preparation is less than 2.5 nm. The However, when treated at high temperature, the phase-separated silica becomes an adhesive, and the single crystalline ceria-coated composite particles of the present invention can not be obtained by crushing in a later step.

In order to obtain CeO ₂ ultrafine particles of 2.5 nm or more in the blending step, the temperature of the silica hollow fine particle dispersion when adding the cerium salt is preferably 70 ° C. or less in order to suppress reaction with silica. . At this time, some CeO ₂ ultrafine particles are already crystallized without heating and aging by keeping the oxidation-reduction potential during preparation in a predetermined range. On the other hand, even if heat treatment and aging are carried out in the liquid phase after blending at a temperature exceeding 70 ° C., the CeO ₂ ultrafine particles do not grow to 2.5 nm or more, and crystallization tends not to occur.
The CeO ₂ ultrafine particle-containing layer elutes the surface of the silica hollow fine particles by the reaction between the silanol groups on the surface of the silica hollow fine particles and a product (cerium hydroxide or the like) obtained by neutralization of the cerium salt solution. It is presumed that it is solidified by being formed by the influence of oxygen (derived from the blown air etc.) and the like.
Thereafter, dried, and baked at about 400 to 1200 ° C., the CeO ₂ is present inside the ultrafine particle-containing layer, the particle diameter is 2.5nm or more, CeO ₂ ultrafine particles of less than 8 nm, cerium silicate The cerium atoms present in the layer are incorporated to grow the particle size, and finally the crystalline ceria particles (ceria particles) grown to an average crystallite size of about 8 to 30 nm are formed (FIG. 1 ( c)). Further, the cerium silicate layer (for example, CeO ₂ · SiO ₂ · SiOH) becomes a cerium-containing silica layer by thermal decomposition, thermal diffusion, or the like (see FIG. 1 (c)). Therefore, the crystalline ceria particles are present in a dispersed state in the cerium-containing silica layer.
FIG. 1C shows an example in which all of the silica constituting the silica hollow fine particles is changed to a substance constituting the cerium-containing silica layer as the outer shell, but a part of the silica hollow fine particles is cerium-containing. It may remain inside the silica layer. Even in such a case, they are included in the composite particle of the present invention.
In addition, crystalline ceria particles (child particles) formed by such a mechanism are less likely to cause cohesion of particles. In addition, since a part of cerium contained in the cerium silicate layer does not become crystalline ceria particles and remains, a cerium-containing silica layer is formed.

When the preparation temperature is higher than 70 ° C. and the redox potential is kept in a predetermined range, the reactivity between cerium hydroxide etc. and the hollow silica particles is increased, and the elution amount of the hollow silica particles is significantly increased. In the hollow silica particles, for example, the diameter of the voids of the hollow silica particles is maintained, and the volume is reduced by 50 to 60% when the thickness is about 1/2. The dissolved silica contained in the CeO ₂ ultrafine particles-containing layer, the preceding example, CeO ₂ silica concentration composition of ultrafine particles-containing layer is about 20%, the ceria concentration is about 80%, CeO ₂ containing ultrafine particles The proportion of silica in the layer increases. Then, when crystal growth of ceria particles is performed to 8 to 30 nm by firing, cerium atoms separated from the cerium silicate layer are deposited and grown on ceria particles, resulting in phase separation (diffusion) of cerium atoms. The coated silica will cover the ceria particles, and the ceria child particles will be covered with the silica film. At this time, if the firing temperature is high, the silica acts as an adhesive and promotes the coalescence of the particles, so that it can not be crushed into a monodispersed state by crushing in a later step. When the firing temperature is low, crushing is facilitated, but since ceria particles do not grow, the polishing rate can not be obtained.

Furthermore, when the blending temperature is over 70 ° C. and the oxidation-reduction potential is kept within a predetermined range, the crystallite diameter after blending becomes as small as 2.5 nm or less, and in order to grow ceria particles to a predetermined size by firing. Requires diffusion of more cerium atoms from the cerium silicate layer, and as a result, the silica concentration in the cerium silicate layer increases and the tendency of the silica coating covering the child particles to increase increases.
When the preparation temperature during the reaction of the silica hollow fine particle dispersion and the metal salt of cerium is 0 to 70 ° C. and the oxidation-reduction potential is kept within a predetermined range, the reactivity between the cerium hydroxide and the silica hollow fine particles is suppressed. Silica hollow fine particles do not dissolve so much, and the prepared silica hollow fine particles maintain, for example, the diameter of the voids of the silica hollow fine particles, and the thickness is reduced to about 10 to 20% and the volume is reduced to about 10 to 25%. Be Therefore, in the case of the above-mentioned example, the composition of the CeO ₂ ultrafine particle-containing layer has a silica concentration of about 10% and a ceria concentration of about 90%, the ceria content of the CeO ₂ ultrafine particle-containing layer increases, and contains cerium after firing. A silica layer is formed. Moreover, since the crystal size of ceria after blending is about 2.5 nm or more and less than 8 nm (as an example, 5 to 7 nm), the amount of cerium atoms diffused to grow ceria particles into a predetermined size by firing is small. Well, as a result, a large amount of cerium remains in the cerium silicate layer, and crystal growth occurs by low-temperature firing, so that ceria particles of 8 to 30 nm are obtained. Therefore, when prepared at 0 to 70 ° C., ceria particle is dispersed in the layer of the cerium-containing silica layer.

  Further, when ceria particles are 8 nm or more in the preparation stage, ceria particles are coalesced with each other, and uniform ceria particles are not monodisperse arrayed inside the cerium-containing silica layer, so that excellent polishing characteristics can not be obtained.

  Such fine particles of the present invention have a hollow structure, so the density is low and it is difficult to settle in the dispersion. Further, when used as an abrasive, the number of particles per unit weight can be increased. That is, since polishing is usually performed at a specific solid content concentration, the number of particles increases at the same solid content concentration, so that the polishing rate can be increased. In addition, scratches are unlikely to occur because the gap serves as a cushion. In addition, since the particle size of the crystalline ceria particles is uniform, scratching hardly occurs even if the polishing pressure is increased. Here, if the polishing pressure is increased, there is a concern that the crystalline ceria particles will come off, but in the case of the fine particles of the present invention, the crystalline ceria particles are firmly held by the cerium-containing silica layer forming the outer shell. Even if the polishing pressure is increased, the crystalline ceria particles hardly fall off. In addition, although it has a hollow structure, the cerium-containing silica layer has a sufficient strength against a longitudinal load, so that the composite fine particles of the present invention are not destroyed during polishing.

Next, the composite particle of the present invention will be further described with reference to FIGS. 2 and 3.
The composite particle of the present invention has the structure illustrated in FIG. 2 and FIG. 2 (a), 2 (b), 3 (a) and 3 (b) are schematic views of the cross section of the composite particle of the present invention. 2 (a) and 3 (a) are types in which a part of child particles are exposed to the outside, and FIGS. 2 (b) and 3 (b) show all child particles exposed to the outside Not buried type. FIG. 2 shows the type in which the hollow silica particles are left, and FIG. 3 shows the type in which the hollow silica particles are not left.
As shown in FIGS. 2 and 3, the composite fine particle 20 of the present invention has a hollow structure having a void 10 inside the cerium-containing silica layer 12 as an outer shell, and crystalline ceria is provided inside the cerium-containing silica layer. Child particles 14 as a main component are dispersed.
2 and 3 are examples of measurement points X, X ′, Y, and Z at which TEM-EDS analysis is performed.

Although the voids 10, the cerium-containing silica layer 12 and the child particles 14 are clearly distinguished for easy understanding in the schematic views of FIGS. 2 and 3, the composite fine particles of the present invention have the mechanism described above. In fact, they are present together as they are supposed to be formed, and except for the contrast or EDS analysis in the STEM / SEM image, the void 10, the cerium-containing silica layer 12 and the child particles 14 are It is difficult to distinguish clearly.
However, when STEM-EDS analysis is performed on the cross section of the composite fine particle of the present invention to measure the elemental concentration of Ce and Si, it can be confirmed that the structure is as shown in FIG. 2 or 3.

  That is, the element of Ce and Si at the measurement point X of the cross-section of the composite fine particle of the present invention shown in FIG. 2 is performed by performing EDS analysis in which an electron beam is selectively irradiated to a place specified by a scanning transmission electron microscope (STEM). When the concentration is measured, all become zero%. In other words, when EDS analysis in which the electron beam is selectively irradiated to the location specified by the scanning transmission electron microscope (STEM), the elemental concentration of both Ce and Si in the particles is zero. The part that became% is the air gap 10. In FIG. 2, there is no Si element because the inside of the circular line surrounding 10 is a void, but the outside of this line is a residue 11 of hollow silica fine particles. Exists. Therefore, EDS analysis is performed by selectively irradiating an electron beam to a place specified by a scanning transmission electron microscope (STEM), and the Ce and Si at the measurement point X ′ of the cross section of the composite fine particle of the present invention shown in FIG. When the element concentration is measured, Ce is almost zero%, and Si element is almost 100%.

  Further, the outside of the silica hollow fine particle residue 11 is a cerium-containing silica layer 12, and when the element concentration of Ce and Si in this portion (for example, measurement point Y) is measured, the sum of the Ce molar concentration and the Si molar concentration is obtained. The ratio (percentage) of Ce molar concentration to (Ce / (Ce + Si) × 100) is 0 to 50%. In other words, when performing an EDS analysis in which an electron beam is selectively irradiated to a location specified by a scanning transmission electron microscope (STEM), the Si element concentration is not zero% (that is, more than zero%). And, a portion where the ratio (percentage) of Ce molar concentration to the total of Ce molar concentration and Si molar concentration (Ce / (Ce + Si) × 100) becomes 0 to 50% is the cerium-containing silica layer 12. Therefore, when silica hollow fine particles remain as shown in FIG. 2, the residue is included in the cerium-containing silica layer 12.

  Furthermore, when the elemental concentration of Ce and Si in the child particles 14 included in the cerium-containing silica layer 12 is measured, for example, at the measurement point Z, the ratio of the Ce molar concentration to the total of the Ce molar concentration and the Si molar concentration (percentage ) (Ce / (Ce + Si) × 100) exceeds 50%. Conversely, when EDS analysis in which the electron beam is selectively irradiated to the location specified by the scanning transmission electron microscope (STEM), the ratio of the Ce molar concentration to the sum of the Ce molar concentration and the Si molar concentration A portion where (percent) (Ce / (Ce + Si) × 100) exceeds 50% is the child particle 14.

Next, although the type in which the hollow silica fine particles shown in FIG. 3 do not remain is described, in principle, it can be considered the same as the type in which the hollow silica fine particles shown in FIG.
That is, EDS analysis in which the electron beam is selectively irradiated to a location specified by a scanning transmission electron microscope (STEM) is performed, and elements of Ce and Si at the measurement point X of the cross section of the composite particle of When the concentration is measured, all become zero%. In other words, when EDS analysis in which the electron beam is selectively irradiated to the location specified by the scanning transmission electron microscope (STEM), the elemental concentration of both Ce and Si in the particles is zero. % Is the void 10.
Here, the outer side of the circular line surrounding 10 in FIG. 3 is the cerium-containing silica layer 12.

  And the outer side of the space | gap 10 is the cerium containing silica layer 12, When the element concentration of Ce and Si in this part (for example, measurement point Y) is measured, Ce molar concentration with respect to the sum total of Ce molar concentration and Si molar concentration The ratio (percentage) (Ce / (Ce + Si) × 100) is 0 to 50%. In other words, when performing an EDS analysis in which an electron beam is selectively irradiated to a location specified by a scanning transmission electron microscope (STEM), the Si element concentration is not zero% (that is, more than zero%). And, a portion where the ratio (percentage) of Ce molar concentration to the total of Ce molar concentration and Si molar concentration (Ce / (Ce + Si) × 100) becomes 0 to 50% is the cerium-containing silica layer 12.

  Furthermore, when the elemental concentration of Ce and Si in the child particles 14 contained in the cerium-containing silica layer 12 is measured, for example, at measurement point Z, the ratio of Ce molar concentration to the total of Ce molar concentration and Si molar concentration (percent ) (Ce / (Ce + Si) × 100) exceeds 50%. Conversely, when EDS analysis in which the electron beam is selectively irradiated to the location specified by the scanning transmission electron microscope (STEM), the ratio of the Ce molar concentration to the sum of the Ce molar concentration and the Si molar concentration A portion where (percent) (Ce / (Ce + Si) × 100) exceeds 50% is the child particle 14.

  Therefore, in the elemental map obtained by conducting STEM-EDS analysis, the voids 10 and the cerium-containing silica layer 12 in the composite fine particle of the present invention are distinguished by a line in which both Ce molar concentration and Si molar concentration are zero%. be able to. In the element map obtained by performing STEM-EDS analysis, the cerium-containing silica layer 12 and the child particles 14 in the composite fine particles of the present invention have a ratio of Ce molar concentration to the sum of Ce molar concentration and Si molar concentration ( It can distinguish by the line which percentage becomes (Ce / (Ce + Si) x100) 50%. The portion where (Ce / (Ce + Si) × 100) exceeds 50% is the child particle 14, the Si element concentration is not zero% (that is, more than zero%), and the Ce molar concentration and the Si mole The portion where the ratio (percentage) of Ce molar concentration to the total concentration (Ce / (Ce + Si) × 100) is 0 to 50% is the cerium-containing silica layer 12.

  In the present specification, STEM-EDS analysis is performed by observation at 800,000 times.

  Since the composite fine particle of the present invention is an aspect as shown in FIG. 2 or FIG. 3, STEM-EDS analysis is performed on the cross section, and element mapping is performed. It has a layer (consisting of ceria fine particles) having a relatively high concentration of at least one ceria.

<Cerium-containing silica layer>
The composite fine particles of the present invention have a hollow structure having voids inside a cerium-containing silica layer as an outer shell. And the child particle | grains which have a crystalline ceria as a main component are disperse | distributing in the inside of a cerium containing silica layer.

  By adopting such a structure, it is difficult for the child particles to fall off due to the crushing process during production or the pressure during polishing, and even if some of the child particles are missing, many child particles can be dropped off. Therefore, since the composite particles of the present invention are not destroyed because they are present in the cerium-containing silica layer and the strength of the cerium-containing silica layer is sufficient, the polishing function is not deteriorated.

  As described above, when STEM-EDS analysis is performed on the composite particles of the present invention, and the elemental concentration of Ce and Si in the cross section of the composite particles of the present invention shown in FIG. 2 or FIG. This is a portion where the ratio (percentage) of Ce molar concentration to the total of Ce molar concentration and Si molar concentration (Ce / (Ce + Si) × 100) is 0 to 50%.

  In the image (TEM image) obtained by observing the composite fine particles of the present invention using a transmission electron microscope, the image of the child particles appears dark in the peripheral portion of the composite fine particles of the present invention. That is, a part of the cerium-containing silica layer appears as a relatively thin image also on the surface side and the inner side of the composite fine particle of the present invention. When this part is subjected to STEM-EDS analysis and the Si molar concentration and Ce molar concentration of the part are determined, it can be confirmed that the Si molar concentration is very high. Specifically, the ratio (percentage) of Ce molar concentration to the total of Ce molar concentration and Si molar concentration (Ce / (Ce + Si) × 100) is 0 to 50%.

The cerium-containing silica layer contains amorphous silica as a main component and further contains cerium separately from the child particles.
The fact that the cerium-containing silica layer is mainly composed of an amorphous silica layer can be confirmed, for example, by the following method. The dispersion containing the composite fine particles of the present invention is dried and then ground using a mortar, for example, to obtain an X-ray diffraction pattern using a conventionally known X-ray diffractometer (for example, RINT 1400 manufactured by Rigaku Denki Co., Ltd.) The peak of crystalline silica such as Cristobalite does not appear. From this, it can be confirmed that the silica contained in the cerium-containing silica layer is amorphous. In such a case, the cerium-containing silica layer is mainly composed of amorphous silica.
Further, the dispersion liquid of the present invention is dried, embedded in a resin, sputter-coated with Pt, and a cross-sectional sample is prepared using a conventionally known focused ion beam (FIB) apparatus. For example, when the FFT sample is obtained by using the conventionally known TEM apparatus and the fast Fourier transform (FFT) analysis for the prepared cross-sectional sample, the diffraction pattern of crystalline silica such as Cristobalite does not appear. From this, it can be confirmed that the silica contained in the cerium-containing silica layer is amorphous. In such a case, the cerium-containing silica layer is mainly composed of amorphous silica.
Further, as another method, a method of observing the presence or absence of lattice fringes by the atomic arrangement of the cerium-containing silica layer using a conventionally known TEM apparatus for a cross-sectional sample prepared in the same manner can be mentioned. If it is crystalline, lattice fringes corresponding to the crystal structure are observed, and if it is amorphous, no lattice fringes are observed. From this, it can be confirmed that the silica contained in the cerium-containing silica layer is amorphous. In such a case, the cerium-containing silica layer is mainly composed of amorphous silica.

As described above, the cerium-containing silica layer has a ratio (percentage) of the Ce molar concentration to the sum of the Ce molar concentration and the Si molar concentration in the element map obtained by conducting STEM-EDS analysis (Ce / (Ce + Si) × 100 ) Is 0 to 50%, but the substances constituting the cerium-containing silica layer are mainly Ce, Si and oxides thereof. Specifically, the total content of Ce, Si and oxygen in the cerium-containing silica layer is preferably 70% by mass or more, more preferably 80% by mass or more, and more preferably 90% by mass or more , 95% by mass or more, more preferably 98% by mass or more.
The cerium-containing silica layer may contain, for example, 10% by mass or less of La, Ce, and Zr, and may contain other impurity elements.

The thickness of the cerium-containing silica layer as the outer shell is not particularly limited as long as it is within a range suitable for constituting composite fine particles (average particle diameter of 20 to 400 nm), but the average thickness thereof is not limited. Is preferably 5 to 30 nm, more preferably 8 to 20 nm.
In addition, the average thickness of the cerium-containing silica layer is obtained by drawing a straight line at any 12 points from the center of the composite fine particle of the present invention to the outermost side of the cerium-containing silica layer in the element map obtained by STEM-EDS analysis. Above, the outline of the cavity where the Ce molar concentration and the Si molar concentration specified from the element map obtained by performing the STEM-EDS analysis as described above are both 0%, and the cerium of the composite fine particle of the present invention The distance to the outermost side of the contained silica layer (the distance on the line passing through the center of the composite fine particle of the present invention) is measured, and they are obtained by simple averaging. In addition, the center of the composite particle of the present invention means an intersection point of the long axis and the short axis of the composite particle of the present invention described later.

  In the composite fine particle of the present invention, at least a part of the surface of the child particle is coated with the cerium-containing silica layer, so that the outermost surface of the composite fine particle of the present invention (the outermost side of the cerium-containing silica layer) is —OH of silica. The group will be present. For this reason, when used as an abrasive, the composite fine particles of the present invention are repelled by charges due to —OH groups on the surface of the polishing substrate, and as a result, adhesion to the surface of the polishing substrate is considered to be reduced.

  In general, ceria has a potential different from that of silica, a polishing substrate, and a polishing pad, and as the pH goes from alkaline to near neutral, the negative zeta potential decreases, and in the weakly acidic region, the opposite positive potential have. For this reason, at an acidic pH during polishing, ceria adheres to the polishing base material and the polishing pad and tends to remain on the polishing base material and the polishing pad due to the difference in the magnitude of the potential and the difference in polarity. On the other hand, since the composite fine particles of the present invention have silica on the outermost surface (outermost side of the cerium-containing silica layer) as described above, the potential becomes a negative charge due to silica, so that the pH is alkaline to acidic. The negative potential is maintained, and as a result, abrasive residue on the polishing substrate or the polishing pad is less likely to occur. When pulverizing while maintaining pH 8.6 to 10.8 during the pulverization treatment in step 2 in the production method of the present invention, a part of the silica (cerium-containing silica layer silica) on the surface of the composite fine particles of the present invention is dissolved. . When the dispersion of the present invention produced under such conditions is adjusted to pH <7 when applied to polishing applications, dissolved silica is deposited on the composite fine particles (abrasive grains) of the present invention. The surface will have a negative potential. When the potential is low, silica may be added to moderately reinforce the cerium-containing silica layer.

<Child particles>
In the composite particles of the present invention, child particles (hereinafter also referred to as "ceria child particles") mainly composed of crystalline ceria are dispersed inside a cerium-containing silica layer as an outer shell.

In addition, ceria particle may be laminated inside the cerium-containing silica layer, and the shape is not particularly limited, such as a spherical shape, an elliptical shape, a rectangular shape, etc. Furthermore, the particle diameter distribution is also sharp even if uniform. May be
Some of the ceria particles are buried in the cerium-containing silica layer, and others are partially exposed from the cerium-containing silica layer.

As described above, the child particles have a Ce molar concentration ratio (percentage) (Ce / (Ce + Si) × 100) to the total of the Ce molar concentration and the Si molar concentration in the element map obtained by performing the STEM-EDS analysis. The material constituting the cerium-containing silica layer is mainly Ce, Si, and oxides thereof, although the portion is more than 50%. Specifically, the total content of Ce, Si and oxygen in the child particles is preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and 95 More preferably, it is more than 98 mass%, and it is still more preferable that it is 98 mass% or more.
The child particles may contain, for example, 10% by mass or less of La, Ce, and Zr, and may contain other impurity elements.

  The child particles mainly composed of crystalline ceria in the present invention are dispersed inside the cerium-containing silica layer, and the coefficient of variation (CV value) in the particle size distribution of the child particles is preferably 14 to 60%. . That is, it is preferable that the width of the particle size distribution of the daughter particles is large. When the dispersion liquid of the present invention containing the composite fine particles of the present invention having such ceria particles having a large particle size distribution width is used as an abrasive dispersion for polishing, the child particles having a large particle diameter are obtained at the initial stage of polishing. Polishing is performed in contact with the substrate to be polished. Even if the child particles come off due to the polishing pressure, or wear or breakage occurs, the child particles having a small particle size come into contact with the substrate to be polished, so that the contact area can be kept high. Therefore, polishing with stable polishing rate is performed efficiently.

  In the present invention, the coefficient of variation (CV value) in the particle size distribution of the child particles dispersed inside the cerium-containing silica layer is preferably 14 to 60%, more preferably 16 to 55%, More preferably, it is 18 to 53%.

In the present invention, the particle size distribution of the child particles is measured as follows.
First, the composite fine particle of the present invention is observed at 800,000 times by STEM-EDS analysis, and the ratio (percentage) of Ce molar concentration to the sum of Ce molar concentration and Si molar concentration in the obtained elemental map (Ce / (Ce + Si A child particle is specified by specifying a line where x100) becomes 50%. Next, the maximum diameter of the child particles is taken as the major axis, the length is measured, and the value is taken as the major diameter (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). Then, a geometric average value of the long diameter (DL) and the short diameter (DS) is obtained, and this is used as the particle diameter of the child particles.
In this manner, the particle size can be measured for 100 or more child particles to obtain a particle size distribution.

  In the present invention, the coefficient of variation (CV value) in the particle size distribution of child particles is obtained by obtaining the standard deviation and the number average value using the particle size distribution obtained as described above as a population, and then calculating the standard deviation as a number average value Calculated by dividing by and multiplying by 100 (ie, standard deviation / number average value × 100).

The average particle diameter of the secondary particles is preferably 8 to 30 nm, and more preferably 14 to 23 nm.
When the average particle size of the secondary particles exceeds 30 nm, in the step 2, precursor particles having such ceria child particles tend to be sintered or coagulated after firing and also difficult to be crushed. In addition, when cerium is discharged from the cerium-containing silica layer, the strength of the cerium-containing silica layer may be reduced and the composite particles of the present invention may be broken. Such a ceria-based composite hollow particle dispersion may cause scratching on the object to be polished even when used for polishing applications. When the average particle size of the secondary particles is less than 8 nm, it may be difficult to obtain a practically sufficient polishing rate when used similarly for polishing.

  In the present invention, the average particle diameter of child particles means the number average diameter in the particle diameter distribution obtained as described above.

The child particles may be stacked. That is, multiple particles may be present in a radial line from the center of the composite fine particle of the present invention in the inside of the cerium-containing silica layer as the outer shell.
In addition, child particles may be buried in the cerium-containing silica layer, or may be partially exposed to the outside of the cerium-containing silica layer, but if child particles are buried in the cerium-containing silica layer, Since the storage stability and the polishing stability are improved, and the remaining abrasives are reduced on the substrate after polishing, it is preferable that the child particles be buried inside the cerium-containing silica layer.

  The shape of the secondary particles is not particularly limited. For example, a true spherical shape, an elliptical shape, or a rectangular shape may be used. When the dispersion liquid of the present invention is used for polishing and a high polishing rate is to be obtained, the child particles are preferably non-spherical and more preferably rectangular.

  The child particles dispersed inside the cerium-containing silica layer may be in a monodispersed state, and the child particles are stacked (that is, a plurality of child particles are stacked in the thickness direction of the cerium-containing silica layer) Or a plurality of child particles may be connected.

In the present invention, the child particles contain crystalline ceria as the main component.
The fact that the child particles are mainly composed of crystalline ceria means that, for example, after drying the dispersion of the present invention, the obtained solid is pulverized using a mortar to obtain the composite fine particles of the present invention. Then, this is subjected to X-ray analysis using, for example, a conventionally known X-ray diffraction apparatus (for example, RINT1400, manufactured by Rigaku Corporation), and only the ceria crystal phase is detected in the obtained X-ray diffraction pattern. This can be confirmed. In such a case, the child particles contain crystalline ceria as a main component. The crystal phase of ceria is not particularly limited, and examples thereof include Ceriaite.

The secondary particles contain crystalline ceria (crystalline Ce oxide) as a main component, and may contain other elements such as elements other than cerium. A hydrous cerium compound may also be included as a polishing co-catalyst.
However, as described above, when the composite fine particle of the present invention is subjected to X-ray diffraction, only the crystalline phase of ceria is detected. That is, even if a crystal phase other than ceria is contained, the content is small or because it is in solid solution in the ceria crystal, it falls outside the detection range by X-ray diffraction.

The average crystallite diameter of the ceria particle is calculated using the full width at half maximum of the maximum peak appearing in the chart obtained by subjecting the composite fine particle of the present invention to X-ray diffraction. And, for example, the average crystallite diameter of the (111) plane is 8 to 30 nm (full width at half maximum is 1.07 to 0.29 °) and 14 to 23 nm (full width at half maximum is 0.62 to 0.37 °) It is preferably 15 to 22 nm (full width at half maximum is 0.58 to 0.38 °), more preferably.
In many cases, the peak intensity of the (111) plane is maximum, but the peak intensity of other crystal planes, for example, the (100) plane may be maximum. In that case, the calculation can be performed in the same manner, and the average crystallite diameter in that case may be the same as the average crystallite diameter of the (111) plane.

The measurement method of the average crystallite diameter of the child particles is shown below by taking the case of (111) plane (near 2θ = 28 degrees) as an example.
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 full width at half maximum of the peak of the (111) plane near 2θ = 28 degrees in the obtained X-ray diffraction pattern is measured, and the average crystallite diameter can be obtained by the following Scherrer equation.
D = Kλ / β cos θ
D: Average crystallite diameter (angstrom)
K: Scherrer constant (in the present invention, K = 0.94)
λ: X-ray wavelength (1.5419 angstrom, Cu lamp)
β: full width at half maximum (rad)
θ: Reflection angle

It is preferable that a silicon atom is solid-solved in crystalline ceria which is a main component of the particle. In general, solid solution means that two or more kinds of elements (metal or non-metal) are dissolved in each other and the whole is a uniform solid phase. And classified into substitutional solid solution and interstitial solid solution. Substitution-type solid solutions can easily occur in atoms with a close atomic radius, but Ce and Si have a large difference in atomic radii, so at least substitution-type solid solutions are unlikely to occur. In addition, in the crystal structure of Cerianite, the coordination number of Ce as viewed from the center of Ce is 8, but when, for example, Si is replaced with Ce by 1: 1, the coordination number of Ce should be 7. However, in the analysis result of Example 1 of the composite fine particle of the present invention, the average coordination number of Ce viewed from the Ce center is 8.0, and the average coordination number of Si is 1.2. It is presumed that the preferred embodiment of the composite fine particles is an interstitial type. Moreover, from the analysis result of the preferred embodiment of the composite fine particle of the present invention, the inter-atomic distance of Ce—Si is smaller than the inter-atomic distance of Ce—Ce. Therefore, the preferred embodiment of the fine composite particle of the present invention is an interstitial type. It is presumed to be a solid solution. That is, it is preferable to satisfy the relationship of R ₁ <R ₂ when the cerium-silicon interatomic distance is R ₁ and the cerium-cerium interatomic distance is R ₂ for cerium atoms and silicon atoms contained in child particles .
Conventionally, it is known that when a substrate with a silica film or a glass substrate is polished using ceria particles as abrasive grains, the polishing rate is specifically high as compared with the case of using other inorganic oxide particles. . One of the reasons why ceria particles exhibit a particularly high polishing rate for a substrate with a silica film is that trivalent cerium contained in the ceria particles has a high chemical reactivity with respect to the silica coating on the substrate to be polished. It is pointed out that it has. Cerium in cerium oxide can be trivalent and tetravalent valence, but high purity cerium oxide particles used as abrasives for semiconductors are high purity cerium salts such as cerium carbonate fired at a high temperature of 700 ° C. Go through the process of For this reason, the valence of cerium in the calcined ceria particles is mainly tetravalent, and even if trivalent cerium is contained, the content thereof is not sufficient.
In a preferred embodiment of the composite fine particles of the present invention, it is considered that Si atoms are intrusive solid solution in the CeO ₂ crystal in the child particles (ceria fine particles) existing on the outer surface side. By solid solution of Si atoms, that crystal strain of the CeO ₂ crystal occurs, resulting many chemically active trivalent cerium with respect to SiO ₂ becomes large oxygen defects by firing at a high temperature, the CeO ₂ As a result of promoting chemical reactivity, it is presumed that the above-mentioned high polishing rate is exhibited. In order to increase the trivalent cerium content, La, Zr or the like may be doped.
The interatomic distance between the cerium atom and the silicon atom such as R ₁ and R ₂ described above can be determined using the conventionally known X-ray absorption spectrometer (for example, R-XAS Looper manufactured by Rigaku Corporation). After measuring the X-ray absorption spectrum at the end (5727 eV) and obtaining the EXAFS vibration appearing in the X-ray absorption spectrum, a value determined by a conventionally known method (for example, analysis using software REX-2000 made by Rigaku) Shall mean.

<Gap>
The composite fine particles of the present invention have a hollow structure having voids inside a cerium-containing silica layer as an outer shell.
The size of the gap is not particularly limited. The size of the void is the size of the composite fine particle of the present invention minus the thickness of the cerium-containing silica layer.

The average diameter of the voids is preferably in the range of 15 to 300 nm.
Here, the average diameter of the voids is measured by the following method.
First, the composite fine particles of the present invention are observed at 800,000 times by STEM-EDS analysis, and a portion where both Ce molar concentration and Si molar concentration are 0% is specified as a void. Next, the maximum diameter of the gap is taken as the major axis, the length is measured, and the value is taken as the major diameter (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 with a line that specifies the air gap are obtained, a distance between the two points is measured, and a minor axis (DS) To do. Then, a geometric average value of the long diameter (DL) and the short diameter (DS) is obtained, and this is set as the diameter of the gap.
Thus, the diameter is measured with respect to the voids of 50 particles, and a value obtained by simple averaging is determined as the average diameter.

  The shape of the void is not particularly limited, and it may be, for example, spherical, scaly, short fibrous, tetrahedral (triangular pyramidal), hexahedral, octahedral, plate-like, irregular, porous Good.

<Composite fine particles of the present invention>
The composite particle of the present invention will be described.
As described above, the composite fine particles of the present invention are as follows: [1] The ceria-based composite hollow fine particles have a hollow structure having voids inside a cerium-containing silica layer as an outer shell, and crystals are formed inside the cerium-containing silica layer. [2] The ceria-based composite hollow microparticles are detected only by the ceria crystal phase when subjected to X-ray diffraction, and [3] the ceria-based composite hollow microparticles are dispersed. Is measured by X-ray diffraction, and the average crystallite diameter of the crystalline ceria is 8 to 30 nm.

And as for the composite microparticles | fine-particles of this invention, it is further preferable that mass ratio of a silica and a ceria is 100: 5-450, and it is more preferable that it is 100: 11-410. If the amount of ceria relative to silica is too large, the composite fine 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. Furthermore, fusion between particles proceeds. As a result, the roughness of the substrate surface increases (deterioration of the surface roughness Ra), scratches increase, and free ceria remains on the substrate, causing problems such as adhesion to the waste liquid piping of the polishing apparatus. It is easy to get along.
In addition, the silica used as the object in calculating the mass ratio of the above silica (SiO ₂ ) and ceria (CeO ₂ ) means all silica (SiO ₂ ) contained in the composite fine particles of the present invention.

The content (% by mass) of the silica (SiO ₂ ) and ceria (CeO ₂ ) in the composite fine particles of the present invention is first determined by weighing the solid concentration of the dispersion of the present invention by performing 1000 ° C. thermal loss.
Next, the content (mass%) of cerium (Ce) contained in the predetermined amount of the composite fine particles of the present invention is determined by ICP plasma emission analysis, and converted to oxide mass% (CeO ₂ mass%, etc.). Then, assuming that the component other than CeO ₂ constituting the composite particles of the present invention is SiO ₂ , SiO ₂ mass% can be calculated.
In the production method of the present invention, the mass ratio of silica to ceria can also be calculated from the amounts used of the silica source material and the ceria source material which were added when preparing the dispersion liquid of the present invention. This can be applied when ceria and silica are not dissolved and removed, and in such a case, the amount of ceria and silica used agree well with the analytical value.

As an embodiment of the composite fine particle of the present invention, a particle connection type composite fine particle formed by connecting the composite fine particles and a single particle (non-connected particle) type in which a single composite fine particle without a connective structure exists independently. Composite particulates can be mentioned. The composite particles of the present invention may be any of them, or may be a mixture of both. In the case where the contact area with the substrate can be kept high and importance is attached to the high polishing rate, the particle connection type is desirable. The particle connection type is one in which two or more of the composite fine particles of the present invention are partially bonded to each other, and the number of connections is preferably 3 or less.
In addition, the particle | grain connection type particle | grain means the thing (condensed particle | grain) which a chemical bond of the extent which can not be re-dispersed between particle | grains arises, and particle | grains connect. Moreover, a single particle does not mean that a plurality of particles are connected, and does not aggregate regardless of the morphology of the particles.
The following embodiment 1 can be exemplified as the composite fine particle dispersion of the present invention in the case where the improvement of the polishing rate to the substrate to be polished is emphasized.
[Aspect 1] The composite particle of the present invention is characterized in that the number ratio of particles having a minor axis / major axis ratio of less than 0.8 as measured by an image analysis method is 45% or more. Dispersion.
Further, the following can be exemplified as the composite fine particle dispersion of the present invention in the case where importance is given to the fact that the surface roughness on the substrate to be polished is at a low level.
[Aspect 2] The composite particle of the present invention is characterized in that the number ratio of particles having a minor axis / major axis ratio of 0.8 or more measured by an image analysis method is 40% or more. Dispersion.

A method of measuring the minor axis / major axis ratio by the image analysis method will be described. In a photographic projection drawing obtained by photographing a composite fine particle of the present invention at a magnification of 300,000 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 of 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 determined. Then, a value obtained by simply averaging the minor axis / major axis ratio of any 50 particles observed in the photographic projection diagram is defined as the minor axis / major axis ratio of the composite fine particles of the present invention.
Here, the number ratio (%) of particles having a minor axis / major axis ratio of less than 0.80 or 0.80 or more in arbitrary 50 particles observed in a photographic projection diagram can be obtained.

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

  The dispersion of the present invention can optionally limit the number of coarse particles contained in the dispersion. For example, the number of coarse particles of 0.51 μm or more that can be contained in the dispersion of the present invention is not particularly limited, but when high polishing accuracy is required, it is 150 million particles / dry. It is preferable that it is cc or less. The number of coarse particles is preferably 150 million particles / cc or less, more preferably 120 million particles / cc or less. Coarse particles having a diameter of 0.51 μm or more may cause polishing scratches and may further deteriorate the surface roughness of the polishing substrate. Usually, when the polishing rate is high, while the polishing rate is high, polishing flaws frequently occur and the surface roughness of the substrate tends to deteriorate. However, when the composite fine particles of the present invention are particle-linked, a high polishing rate can be obtained. On the other hand, when the number of coarse particles of 0.51 μm or more is 150 million particles / cc or less, there are few polishing flaws and the surface The roughness can be kept low.

In addition, the measuring method of the number of coarse particles which may be contained in the dispersion liquid of this invention is as follows.
After diluting and adjusting the sample to 0.1% by mass with pure water, 5 ml is collected and injected into a conventionally known coarse particle number measuring device. Then, the number of coarse particles of 0.51 μm or more is obtained. This measurement is performed three times, a simple average value is determined, and the value is multiplied by 1000 to obtain a value of the number of coarse particles of 0.51 μm or more.

  The shape of the composite fine particle of the present invention is not particularly limited. For example, it may be spherical, rod-like, short fiber-like, tetrahedron-like (triangular pyramidal), hexahedral, octahedral, plate-like, indeterminate, porous It may be

The composite particle of the present invention preferably has a specific surface area of 4 to 100 m ² / g, and more preferably ^{20 to} 70 m ² / g.

Here, a method of 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. The liquid nitrogen temperature is maintained in the air stream and nitrogen is equilibrated to the sample. 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 composite fine particles of the present invention preferably have a density of 3.2 to 5.0 g / cc, and more preferably 3.5 to 4.5 g / cc.

Here, the method of measuring the density will be described.
First, the temperature of the sample chamber of the density measuring apparatus is set to 25 ° C., N ₂ gas is flowed in advance, and the volume of the sample chamber is calibrated using a calibration sphere. Next, about 80% of the dried sample is put in the sample cell, and the sample cell is set in the apparatus to start measurement. The density is measured from the volume of the sample obtained from the mass of the sample and the pressure applied to the sample chamber.
The density measurement by such a gas phase substitution method can be performed using, for example, a conventionally known density measuring apparatus.
In the present invention, the density means a value obtained by measuring by such a method unless otherwise specified.

The average particle diameter of the composite particles of the present invention is 20 to 400 nm, preferably 30 to 300 nm, and more preferably 50 to 200 nm. When the average particle size of the composite fine particles of the present invention is in the range of 20 to 400 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 means the number average value of the average particle size measured by an image analysis method.

Here, the measuring method of the average particle diameter by the image analysis method is demonstrated. In a photographic projection drawing obtained by photographing a composite fine particle of the present invention at a magnification of 300,000 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 of 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). Then, the geometric mean value of the major diameter (DL) and the minor diameter (DS) is determined, and this is taken as the mean particle diameter of the composite fine particles.
Thus, an average particle diameter is measured about 50 or more composite particles, and those number average values are calculated.

The composite fine particle of the present invention may contain amorphous silica and ceria, and may contain 10% by mass or less of other materials such as La, Ce and Zr, and may contain crystalline silica and impurity elements.
In addition, in the composite particles of the present invention, the inclusion of each element of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr (hereinafter sometimes referred to as “specific impurity group 1”) It is preferable that each rate is 100 ppm or less. Furthermore, it is preferable that it is 50 ppm or less, and it is more preferable that it is 25 ppm or less.
In the composite fine particle of the present invention, the content of each element of U, Th, Cl and SO ₄ (hereinafter sometimes referred to as “specific impurity group 2”) is preferably 5 ppm or less.

Here, the content of the specific impurity group 1 or the specific impurity group 2 in the composite fine particle of the present invention and the silica hollow fine particles described later means the content rate with respect to the dry amount.
The content ratio with respect to the amount of dry is the ratio of the weight of the measurement object (specific impurity group 1 or specific impurity group 2) to the mass of solids contained in the object (composite fine particles of the present invention or silica hollow fine particles described later) ( It shall mean the value of percentage).

In general, silica hollow fine particles prepared using water glass as a raw material contain about a few thousand ppm in total of the specific impurity group 1 and the specific impurity group 2 derived from the raw water glass.
In the case of a dispersion in which such silica hollow fine particles are dispersed in a solvent, it is possible to reduce the content of the specific impurity group 1 and the specific impurity group 2 by performing an ion exchange treatment. The specific impurity group 1 or the specific impurity group 2 remains in total several ppm to several hundreds ppm. For this reason, when silica hollow fine particles made from water glass are used, impurities are also reduced by acid treatment or the like.
On the other hand, in the case of a dispersion in which silica hollow fine particles synthesized using alkoxysilane as a raw material are dispersed in a solvent, usually, the content of each element in the specific impurity group 1 is preferably 100 ppm or less, More preferably, the content of each element and each anion in the specific impurity group 2 is preferably 20 ppm or less, and more preferably 5 ppm or less.

In addition, each content rate of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn, Zr, U, Th, Cl, and SO ₄ in the composite fine particles or silica hollow fine particles of the present invention is respectively The value obtained by measurement using the following method.
Na and K: Atomic absorption spectroscopic analysis Ag, Ca, Cr, Cu, Fe, Mg, Ni, Zn, Zr, U and Th: ICP-MS (inductively coupled plasma emission spectroscopic mass spectrometry)
・ Cl: Potentiometric titration method ・ SO ₄ : Ion chromatograph

<Dispersion of the present invention>
The dispersion liquid of the present invention will be described.
The dispersion liquid of the present invention is one in which 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. As the dispersion solvent, for example, water such as pure water, ultrapure water, and ion exchange water is preferably used. Furthermore, the dispersion of the present invention is polished by adding one or more selected from the group consisting of a polishing accelerator, a surfactant, a pH adjuster and a pH buffer as an additive for controlling the polishing performance. It is suitably used as a slurry.

  Further, as a dispersion solvent provided with the dispersion liquid of the present invention, for example, alcohols such as methanol, ethanol, isopropanol, n-butanol and methylisocarbinol; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, isophorone, cyclohexanone Ketones such as; Amides such as N, N-dimethylformamide, N, N-dimethylacetamide; Ethers such as diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, 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, 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, chlorobenzene; sulfoxides such as dimethyl sulfoxide; N-methyl-2-pyrrolidone, N-octyl- Organic solvents such as pyrrolidones such as 2-pyrrolidone can be used. You may mix and use these with water.

  It is preferable that solid content concentration contained in the dispersion liquid of this invention exists in the range of 0.3-50 mass%.

The dispersion liquid of the present invention may optionally have a flow potential change amount (ΔPCD) represented by the following formula (1) when cationic colloid titration is performed, and an addition amount (V) of the cationic colloid titration solution in the knick It is preferable that a streaming potential curve having a ratio (ΔPCD / V) of −150.0 to −5.0 is obtained.
ΔPCD / V = (I−C) / V formula (1)
C: flow potential (mV) in the knick
I: flow potential (mV) at the start point of the flow potential curve
V: Addition amount of the cation colloid titration solution in the knick (ml)

  Here, the cation colloid titration is performed by adding the cation colloid titration liquid to 80 g of the dispersion liquid of the present invention in which the solid content concentration is adjusted to 1% by mass. A 0.001 N polyallyldimethyl ammonium chloride solution is used as a cationic colloid titrant.

The flow potential curve obtained by this cationic colloid titration is a graph in which the addition amount (ml) of the cationic titration solution is taken on the X axis, and the flow potential (mV) of the dispersion of the present invention is taken on the Y axis.
The term "knick" refers to a point (inflection point) at which the flow potential rapidly changes in the flow potential curve obtained by cationic colloid titration. The flow potential at the inflection point is C (mV), and the addition amount of the cationic colloid titrant at the inflection point is V (ml).
The starting point of the flow potential curve is the flow potential in the inventive dispersion before titration. Specifically, the point at which the addition amount of the cationic colloid titrant is 0 is taken as the starting point. The flow potential at this start point is I (mV).

  When the value of ΔPCD / V is −150.0 to −5.0, when the dispersion liquid of the present invention is used as an abrasive, the polishing rate of the abrasive is further improved. It is believed that this ΔPCD / V reflects the coverage of the child particles with the cerium-containing silica layer on the surface of the composite fine particle of the present invention and / or the exposure of child particles on the surface of the composite fine particle or the presence of easily removable silica. It is done. When the value of ΔPCD / V is within the above range, the present inventor presumes that the child particles are hardly detached at the time of pulverization by wet and the polishing rate is high. Conversely, when the absolute value of ΔPCD / V is larger than −150.0, the composite fine particle surface is entirely covered with a cerium-containing silica layer, so that it is difficult for child particles to fall off during the crushing process, but polishing. Sometimes, the removal rate of silica is reduced. On the other hand, when the absolute value is smaller than -5.0, it is considered that dropout is likely to occur. The inventor presumes that within the above range, the surface of the child particles is appropriately exposed at the time of polishing so that the child particles are not dropped off and the polishing rate is further improved. As for (DELTA) PCD / V, it is more preferable that it is -145.0--10.0, and it is further more preferable that it is -140.0--20.0.

  In the dispersion of the present invention, when the pH value is in the range of 3 to 8, the flow potential is a negative potential before starting the cationic colloid titration, that is, when the titration amount is zero. Is preferred. This is because when the flow potential is maintained at a negative potential, it is difficult for the abrasive grains (ceria-based composite hollow fine particles) to remain on the polishing base material that also exhibits a negative surface potential.

<Production method of the present invention>
The production method of the present invention will be described.
The manufacturing method of the present invention includes steps 1 to 3 described below.

<Step 1>
In step 1, a silica hollow fine particle dispersion in which hollow silica fine particles are dispersed in a solvent is prepared.
In this specification, “step 1” may be referred to as “preparation step”.

Silica hollow fine particles are mainly composed of amorphous silica and have a hollow structure having voids inside.
The fact that the hollow silica particles contain amorphous silica as a main component can be confirmed, for example, by the following method, as in the case of the above-mentioned cerium-containing silica layer. The silica hollow fine particle dispersion in which the silica hollow fine particles are dispersed in a solvent is dried and then pulverized using a mortar. For example, the X When the line diffraction pattern is obtained, the peak of crystalline silica such as Cristobalite does not appear. From this, it can be confirmed that the silica contained in the silica hollow fine particles is amorphous. In such a case, the silica hollow fine particles are mainly composed of amorphous silica.

  Silica hollow fine particles are mainly composed of Si and oxygen, but may contain 10% by mass or less of La, Ce and Zr, and may contain other impurity elements and crystalline silica.

When it is intended to prepare the dispersion of the present invention to be applied to polishing of semiconductor devices etc. by the manufacturing method of the present invention, silica hollow fine particles using alkoxysilane as a raw material are dispersed in a solvent as a silica hollow fine particle dispersion. It is preferable to use a silica hollow fine particle dispersion. In addition, when using conventionally well-known silica hollow particle dispersion liquid (The silica hollow particle dispersion liquid etc. which were prepared using water glass as a raw material) other than the above as a raw material, the silica hollow particle dispersion liquid is acid-treated and further deionized. Are preferably used. In this case, the content of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr contained in the hollow silica particles is reduced, specifically to 100 ppm or less.
Specifically, as the hollow silica particles in the hollow silica particle dispersion liquid, which is a raw material, those having the following conditions (a) and (b) are suitably used.
(A) The contents of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr are each 100 ppm or less.
(B) The contents of U, Th, Cl and SO ₄ are each 5 ppm or less.

  Here, (a) is the same as the specific impurity group 1 that can be included in the composite fine particles of the present invention, and (b) is the same as the specific impurity group 2 that can be included in the composite fine particles of the present invention. The measurement method of these content rates in the silica hollow fine particles is also measured by the same method as that for measuring the content rates of the specific impurity group 1 and the specific impurity group 2 in the composite fine particles of the present invention.

  The size of the silica hollow fine particles is not particularly limited, but the average particle diameter is preferably 15 to 340 nm, and more preferably 45 to 180 nm.

Here, the average particle diameter of the silica hollow fine particles means the number average value of the average particle diameter measured by the image analysis method.
The measuring method of the average particle diameter by the image analysis method is demonstrated. In a photographic projection drawing obtained by photographing a silica hollow fine particle at a magnification of 300,000 (or 500,000) by a transmission electron microscope, the maximum diameter of the particle is taken as the major axis, and the length is measured. Let the value be 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). Then, the geometric mean value of the major diameter (DL) and the minor diameter (DS) is determined, and this is used as the mean particle diameter of the silica hollow fine particles.
Thus, the average particle diameter is measured for 50 or more silica hollow fine particles, and their number average value is calculated. The value obtained in this manner is taken as the average particle size of the silica hollow fine particles.

As described above, the silica hollow fine particles in the present invention have a structure having voids inside the cerium-containing silica layer as the outer shell, and the cerium-containing silica layer has a thickness that can retain the void structure as particles, It is not particularly limited. For example, the average thickness of the cerium-containing silica layer constituting the hollow silica particles is preferably 5 to 30 nm, and more preferably 8 to 20 nm.
The thickness of the cerium-containing silica layer is measured by an image analysis method.
The image analysis method will be described in detail. In a photographic projection view obtained by photographing a hollow silica fine particle with a transmission electron microscope at a magnification of 300,000 times (or 500,000 times), the maximum diameter of the particles is taken as the major axis, and the length is measured. A point on the axis that bisects the major axis is specified, and this point is defined as the center of the silica hollow fine particles. Next, a straight line is drawn at any 12 points from the center to the outermost edge of the particle, and the lengths of the points intersecting the outline of the cavity and the points intersecting the outermost edge on the straight line are measured. The average value is taken as the thickness of the cerium-containing silica layer of one particle. Then, the thickness of the 50 silica hollow fine particles of the cerium-containing silica layer is determined, and the value obtained by simply averaging them is taken as the thickness of the cerium hollow silica layer of the silica hollow fine particles.

The size of the voids of the hollow silica particles is not particularly limited, but the average diameter is preferably 15 to 300 nm, and more preferably 45 to 100 nm.
Here, the average diameter of the voids is measured by an image analysis method.
The image analysis method will be described in detail. The outline of the voids of the particles is specified in a photographic projection obtained by photographing the hollow silica fine particles with a transmission electron microscope at a magnification of 300,000 times (or 500,000 times). Then, the maximum diameter of the contour is taken as the major axis, the length is measured, and the value is taken as the major diameter (DL). 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 line that specifies the contour are obtained, and the distance between the two points is measured to obtain the minor axis (DS) Do. Then, a geometric average value of the long diameter (DL) and the short diameter (DS) is obtained, and this is set as the diameter of the gap.
Thus, the diameter is measured with respect to the voids of 50 particles, and a value obtained by simple averaging is determined as the average diameter.

  The shape of the hollow silica particle is not particularly limited, and it may be, for example, a sphere, a bowl, a short fiber, a tetrahedron (triangular pyramid), a hexahedron, an octahedron, a plate, an irregular form, or a porous one. It may be.

The silica hollow fine particles preferably have a density of 0.9 to 1.5 g / cc, and preferably 1.1 to 1.3 g / cc (.
Here, the density is measured by the same method as the density of the above-mentioned composite fine particle of the present invention.

The shape of the hollow silica particles may be particle-connected particles or single particles (non-connected particles), and is usually a mixture of both.
Here, in the case where the dispersion of the present invention comprising the hollow silica particles is used for polishing, and when the emphasis is placed on the improvement of the polishing rate to the substrate to be polished, it was measured by the image analysis method of the hollow silica particles. The proportion of particles having a minor axis / major axis ratio of 0.80 or less (preferably 0.67 or less) is preferably 45% or less (more preferably 35% or less). The same is not true when importance is also given to the fact that the surface roughness on the substrate to be polished is at a low level.
In addition, the particle | grain connection type particle | grain means the thing (condensed particle | grain) which a chemical bond of the extent which can not be re-dispersed between particle | grains arises, and particle | grains connect. Moreover, a single particle does not mean that a plurality of particles are connected, and does not aggregate regardless of the morphology of the particles.

  A method of measuring the minor axis / major axis ratio by the image analysis method will be described. In a photographic projection drawing obtained by photographing a silica hollow fine particle at a magnification of 300,000 (or 500,000) by a transmission electron microscope, the maximum diameter of the particle is taken as the major axis, and the length is measured. Let the value be 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 determined. Then, the number ratio (%) of particles having a minor axis / major axis ratio of 0.80 or less or more than 0.80 in any 50 particles observed in the photographic projection diagram is obtained.

  As the hollow silica particles, those having appropriate reactivity with cerium (the weight of the hollow silica hollow particles dissolved in the weight of ceria) are suitably used. Silica hollow fine particles are dissolved by adding a cerium metal salt in the preparation step of step 1 in the production method of the present invention, so that part of the silica is dissolved by cerium hydroxide or the like, and the size of the silica hollow fine particles is reduced. A precursor of a cerium-containing silica layer containing cerium microcrystals is formed on the surface of the hollow silica fine particles. At this time, when the silica hollow fine particles are made of amorphous silica having high reactivity with cerium, the silica hollow fine particles are dissolved and the hollow structure cannot be maintained. In addition, the precursor of the cerium-containing silica layer becomes thick, the cerium-containing silica layer formed by firing becomes thick, the silica proportion of the layer becomes excessively high, and the crushing becomes difficult in the crushing step. . In addition, when the silica hollow fine particles are made of amorphous silica having extremely low reactivity with cerium, the cerium-containing silica layer is not sufficiently formed, and the ceria particles are likely to fall off. When the reactivity with cerium is appropriate, excessive dissolution of silica is suppressed, and the cerium-containing silica layer has an appropriate thickness to prevent detachment of child particles, and when its strength is greater than the strength with the composite fine particles As it is considered, it is desirable because it is easily crushed.

  The method for producing silica hollow fine particles is not particularly limited. For example, as in the method for producing silica hollow fine particles described in Patent Document 3, a method for producing composite oxide core particles comprising silica and an inorganic oxide other than silica. Is mentioned. In addition, a core-shell method of producing silica hollow particles by forming a silica coating layer on core fine particles such as calcium carbonate and removing core fine particles other than silica, a bubble template method of forming a silica coating layer on microbubbles, Spray drying method in which the liquid as raw material is made into a fine mist and sprayed into hot air, emulsion method in which the shell is formed using the reaction at the boundary between the water phase and the oil phase, and finally the nuclear material is removed There is a way.

  In step 1, a silica hollow fine particle dispersion in which silica fine particles are dispersed in a solvent is stirred, and the temperature is maintained at 0 to 70 ° C., the pH is 7.0 to 11.0, and the oxidation-reduction potential is −400 to 300 mV. However, the metal salt of cerium is continuously or intermittently added thereto, and the metal salt of cerium is neutralized to obtain a precursor particle dispersion containing precursor particles.

  The dispersion medium in the silica hollow fine particle dispersion preferably contains water, and an aqueous silica hollow fine particle dispersion (water sol) is preferably used.

The solid content concentration in the silica hollow fine particle dispersion is preferably 1 to 40% by mass on the basis of SiO ₂ conversion. When this solid content concentration is too low, the silica concentration in the production process becomes low, and the productivity may deteriorate.

In the production method of the present invention, for example, when the reaction temperature between the silica hollow fine particles and the metal salt of cerium in Step 1 is higher than 70 ° C., the reactivity of ceria and silica is increased, and dissolution of the silica hollow fine particles proceeds. As a result, the particle diameter of the CeO ₂ ultrafine particles in the precursor particles obtained by drying in the intermediate stage of step 2 is less than 2.5 nm. This indicates that when silica reacts with ceria in a liquid phase in such a high temperature range, silica inhibits ceria particle growth, so that the average particle diameter of ceria after drying is reduced to less than 2.5 nm. .
Even with such precursor particles, it is possible to set the average crystallite diameter of the ceria particles to 8 to 30 nm by setting the firing temperature to 1200 ° C. or higher. Since the silica layer is formed without forming the silica layer, and this silica layer has a strong tendency to cover the ceria particles, there is a problem in that crushing becomes difficult. Therefore, the average crystallite diameter of the CeO ₂ ultrafine particles in the precursor particles after drying is set to 2.5 nm or more by maintaining the reaction temperature at 0 to 70 ° C. and appropriately suppressing the reaction between silica and ceria in the liquid phase. Can be easily crushed. Furthermore, since the average crystallite diameter after drying is large, the firing temperature for setting the average crystallite diameter of the ceria particles to 8 to 30 nm can be lowered, and the thickness of the cerium-containing silica layer formed by firing is excessive. Therefore, crushing is easy.

  Also, impurities are extracted with cation exchange resin or anion exchange resin, or mineral acid, organic acid, etc., and deionization treatment of the silica hollow fine particle dispersion is performed using an ultrafiltration membrane or the like, if necessary. be able to. The silica hollow fine particle dispersion from which impurity ions and the like have been removed by the deionization treatment is more preferable because it easily forms a hydroxide containing silicon on the surface. The deionization treatment is not limited to these.

In step 1, the above-mentioned hollow silica particle dispersion liquid is stirred, the temperature is 0 to 70 ° C., the pH is 7.0 to 11.0, and the redox potential is -400 to 300 mV while the cerium is added thereto. Is added continuously or intermittently. When the redox potential is low, crystals in the form of a rod or the like are formed, so that it is difficult to deposit on the silica hollow fine particles.
Furthermore, when the redox potential is not adjusted to a predetermined range, the CeO ₂ ultrafine particles generated in the preparation process tend to be difficult to crystallize, and the uncrystallized CeO ₂ ultrafine particles are also crystallized by heating and aging after preparation. Is not promoted. Therefore, in order to crystallize to a predetermined size in the baking of Step 2, baking at a high temperature is required, and crushing becomes difficult.

Although the type of metal salt of cerium is not limited, cerium chloride, nitrate, sulfate, acetate, carbonate, metal alkoxide and the like can be used. Specifically, cerous nitrate, cerous carbonate, cerous sulfate, cerous chloride etc. can be mentioned. Among them, trivalent cerium salts such as cerous nitrate, cerous chloride and cerium carbonate are preferable. At the same time as neutralization, crystalline cerium oxide, cerium hydroxide, etc. are generated from the solution which has become supersaturated, and they are quickly coagulated and deposited on the hollow silica particles, and finally CeO ₂ ultrafine particles are formed in monodispersion. This is because that. Furthermore, the trivalent cerium salt reacts appropriately with the hollow silica particles, and a cerium-containing silica layer is easily formed. Further, trivalent cerium having high reactivity with the silica film formed on the polishing substrate is preferable because it is easily formed in the ceria crystal. However, sulfate ion, chloride ion, nitrate ion and the like contained in these metal salts are corrosive. Therefore, if necessary, after preparation, it is necessary to wash in a post process and remove to 5 ppm or less. On the other hand, carbonates are released during preparation as carbon dioxide gas, and alkoxides are preferably used because they decompose into alcohols.

  The addition amount of the metal salt of cerium to the silica hollow fine particle dispersion is such that the mass ratio of silica to ceria in the obtained ceria-based composite fine particles is 100: 1 to 500, as in the case of the composite fine particles of the present invention described above. The amount will be in the range of

After adding the metal salt of cerium to the hollow particle dispersion of silica, the temperature upon stirring is preferably 0 to 70 ° C., more preferably 3 to 40 ° C., and 5 to 30 ° C. More preferable. If this temperature is too low, the reactivity of ceria and silica is reduced, and the solubility of silica is significantly reduced, so that the crystallization of ceria can not be controlled. As a result, a coarse ceria crystalline oxide is formed, and abnormal growth of CeO ₂ ultrafine particles occurs on the surface of the silica hollow fine particles, which makes it difficult to be crushed after firing, or reduces the amount of silica dissolved by the cerium compound. Therefore, the amount of silica supplied to the cerium-containing silica layer is reduced. For this reason, it is possible that the amount of silica which comprises a cerium containing silica layer runs short, and fixation of ceria child particle becomes difficult to occur. On the contrary, if this temperature is too high, the solubility of silica is remarkably increased and the formation of crystalline ceria oxide is considered to be suppressed. And the silica hollow fine particles may be dissolved and the hollow structure may not be maintained, and furthermore, scale etc. may easily occur on the reactor wall surface, which is not preferable. The hollow silica fine particles are preferably those which are difficult to dissolve in a cerium compound (neutralization product of a cerium salt). In the case of the hollow silica particles that are easily dissolved, the crystal growth of ceria is suppressed by the silica, and the particle diameter of the CeO ₂ ultrafine particles in the preparation step becomes less than 2.5 nm.
If the particle size of the CeO ₂ ultrafine particles in the preparation stage is less than 2.5 nm, the firing temperature needs to be increased in order to make the ceria particle size after firing 8 nm or more. It could be Soluble hollow silica fine particles can be prevented from being soluble when used as raw materials after being dried at 100 ° C. or higher.

In addition, the time for stirring the silica hollow fine particle dispersion is preferably 0.5 to 24 hours, and more preferably 0.5 to 18 hours. If this time is too short, the CeO ₂ ultrafine particles aggregate, making it difficult to react with the silica on the surface of the hollow silica fine particles, which is not preferable in that there is a tendency to form composite fine particles that are difficult to be crushed. Conversely, even if this time is too long, the formation of the CeO ₂ ultrafine particle-containing layer is uneconomical because the reaction does not proceed any further. In addition, you may age at 0-70 degreeC if desired after the addition of the said cerium metal salt. Aging is effective in promoting the reaction of the cerium compound and, at the same time, the effect of adhering the CeO ₂ ultrafine particles which are not attached to the silica hollow particles and released onto the silica hollow particles.

  The pH range of the silica hollow fine particle dispersion when adding a cerium metal salt to the silica fine hollow particle dispersion and stirring is 7.0 to 11.0, but 7.0 to 9.0. Is preferable, and it is more preferable to set it as 7.6-8.6. 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 thereof include aqueous ammonia solutions, alkali hydroxides, alkaline earth metals, and aqueous solutions of amines, but not limited thereto.

Moreover, the metal salt of cerium is added to a silica hollow particle dispersion liquid, and the redox potential of the particle dispersion liquid at the time of stirring is adjusted to -400-300 mV. The redox potential is preferably -300 to 200 mV. This is because when a trivalent cerium metal salt is used as a raw material, the acid reduction potential of the fine particle dispersion is lowered during the preparation. Further, by keeping the redox potential in this range, crystallization of the generated CeO ₂ ultrafine particles is promoted. When the oxidation-reduction potential is less than −400 mV, the ceria compound may not be deposited on the surface of the silica hollow fine particles, and ceria single particles or composite ceria particles such as plates and rods may be generated. Furthermore, the reactivity of cerium hydroxide or the like with respect to the silica hollow fine particles is reduced, and the CeO ₂ ultrafine particle-containing layer is not formed. Even if it is formed, the ratio of silica in the CeO ₂ ultrafine particle layer becomes extremely low. Therefore, it is difficult to form a cerium-containing silica layer internally containing ceria particles after firing.
As a method of keeping the redox potential within the above range, there may be mentioned a method of adding an oxidizing agent such as hydrogen peroxide or blowing air, oxygen and ozone. If these methods are not performed, the redox potential tends to be -400 mV or less.

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. In this step, it is possible to obtain particles having an average crystallite diameter of 2.5 nm or more and less than 10 nm of CeO ₂ ultrafine particles contained in the precursor particles. If the reactivity between silica and ceria is too high, the average crystallite size of CeO ₂ ultrafine particles contained in the precursor particles tends to be less than 2.5 nm. In addition, firing at a high temperature is required. As a result, adhesion between particles becomes strong, which may make crushing difficult.

As described above, in step 1, the silica hollow fine particle dispersion is stirred, and the temperature is maintained at 0 to 70 ° C., the pH is 7.0 to 11.0, and the oxidation-reduction potential is −400 to 300 mV. The metal salt of cerium is continuously or intermittently added, and then, while maintaining the temperature above 70 ° C. and 98 ° C., the pH at 7.0 to 11.0, and the redox potential at −400 to 300 mV, It is preferable to add the cerium metal salt continuously or intermittently to obtain the precursor particle dispersion.
That is, in step 1, the treatment is performed at a temperature of 0 to 70 ° C., but after that, it is preferable to change the temperature to over 70 ° C. and not more than 98 ° C. to obtain the precursor particle dispersion.
This is because when the step 1 is performed, it is easy to obtain the dispersion liquid of the present invention including the composite fine particles of the present invention having a suitable coefficient of variation in the particle size distribution of the child particles.
In addition, the suitable value of pH and the oxidation-reduction potential when adjusting the temperature to be higher than 70 ° C. and not higher than 98 ° C., the adjusting method, and the like are the same as in the case of processing at a temperature of 0 to 70 ° C.

Also, conversely, it is preferable to perform the treatment at a temperature of more than 70 ° C. and 98 ° C. or less before obtaining the treatment at a temperature of 0 to 70 ° C. to obtain the precursor particle dispersion. That is, the silica hollow fine particle dispersion is agitated, and the temperature of the cerium metal is increased to 70 ° C. to 98 ° C., the pH is 7.0 to 11.0, and the oxidation-reduction potential is −400 to 300 mV. A salt is continuously or intermittently added, and then the metal salt of cerium is added thereto while maintaining a temperature of 0 to 70 ° C., a pH of 7.0 to 11.0, and a redox potential of −400 to 300 mV. Are preferably added continuously or intermittently to obtain the precursor particle dispersion.
This is because when the step 1 is performed, it is easy to obtain the dispersion liquid of the present invention including the composite fine particles of the present invention having a suitable coefficient of variation in the particle size distribution of the child particles.
In addition, the suitable value of pH and the oxidation-reduction potential when adjusting the temperature to be higher than 70 ° C. and not higher than 98 ° C., the adjusting method, and the like are the same as in the case of processing at a temperature of 0 to 70 ° C.
Thus, even if it is a case where it mixes by changing temperature during preparation, if the process in which preparation is performed at the temperature of 0-70 ° C is included, composite fine particles will be the same generation mechanism as the above. .

When the reaction is performed in the range of 0 to 70 ° C., the reactivity of cerium with respect to silica is suppressed, and thus, large sized CeO ₂ ultrafine particles are formed, and then the preparation temperature is maintained at 70 ° C. to 98 ° C. or less. When the salt is added, the reactivity of cerium with respect to silica is increased and the dissolution of silica is promoted, so that silica inhibits ceria crystal growth and small-sized CeO ₂ ultrafine particles are generated. Thus, the CeO ₂ ultrafine particles and the CeO ₂ ultrafine particles are obtained by changing the reaction temperature in the preparation step (step 1) to 0 to 70 ° C. as essential and changing the reaction temperature to 70 ° C. to 98 ° C. or less. The particle size distribution of the ceria particles can be widened. If there is a step of adding a cerium metal salt in the range of 0 to 70 ° C., the reaction at a temperature higher than 70 ° C. and 98 ° C. or lower may be performed before or after the reaction at 0 to 70 ° C. Alternatively, the temperature may be changed three times or more.
Moreover, the addition amount of the cerium metal salt in the step of reacting at 0 to 70 ° C. when the reaction temperature is performed in two or more steps is in the range of 10 to 90 mass% with respect to the total addition amount of the cerium metal salt. Is preferred. When exceeding this range, the ratio of large (or small) CeO ₂ ultrafine particles and ceria particles decreases, and the particle size distribution is not so wide.

  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 solid content concentration in precursor particle dispersion liquid 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, centrifugation, or the like.

<Step 2>
In step 2, the precursor particle dispersion is 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 drier, a band drier, a spray drier, etc. can be used.
Preferably, the pH of the precursor particle dispersion before drying is further adjusted to 6.0 to 7.0. When the pH of the precursor particle dispersion before drying is set to 6.0 to 7.0, the surface activity can be suppressed.

  The drying temperature after drying is 400 to 1200 ° C, preferably 900 to 1200 ° C, and more preferably 940 to 1150 ° C. When firing is performed in such a temperature range, crystallization of ceria proceeds sufficiently, and the cerium-containing silica layer in which ceria particles are dispersed has a suitable film thickness, and child particles dispersed in the cerium-containing silica layer It becomes difficult for dropout to occur. Furthermore, by firing in such a temperature range, cerium hydroxide and the like hardly remain. If this temperature is too high, ceria crystals may grow abnormally, the cerium-containing silica layer may become too thick, the amorphous silica constituting the cerium-containing silica layer may crystallize, or fusion of particles may proceed. There is also.

Alkaline metal, alkaline earth metal, sulfate, or the like can be added as a flux component during firing to promote ceria crystal growth. However, the flux component can cause metal contamination and corrosion on the polishing substrate. Therefore, the content of the flux component at the time of firing is preferably 100 ppm or less, more preferably 50 ppm or less, and most preferably 40 ppm or less, per precursor particle (dry).
In addition, the flux component may be used from the raw material colloidal silica or may be used as an alkali used to neutralize the cerium metal salt at the time of preparation, but when an alkali metal or alkaline earth metal coexists at the time of preparation Since the polymerization of the silica hollow fine particles is promoted and densified, the reactivity between the cerium hydroxide and the silica hollow fine particles decreases. Furthermore, since the surface of the hollow silica particles is protected with an alkali metal or alkaline earth metal, the reactivity with cerium hydroxide or the like is suppressed, and a cerium-containing silica layer tends not to be formed. Furthermore, since dissolution of silica is suppressed during preparation, silicon atoms are hardly dissolved in ceria particles.

In addition, when firing in such a temperature range, silicon atoms are dissolved in crystalline ceria which is the main component of the child particles. Therefore, when the cerium-silicon interatomic distance is R ₁ and the cerium-cerium interatomic distance is R ₂ with respect to cerium atoms and silicon atoms contained in child particles, the relationship of R ₁ <R ₂ is satisfied. obtain.

In step 2, a solvent is added to the fired body obtained by firing, and the mixture is crushed by a wet method in a pH range of 8.6 to 10.8 to obtain a fired body crushed dispersion liquid.
Here, before subjecting the fired body to wet disintegration treatment, the fired body may be disintegrated by a dry method and then subjected to wet disintegration treatment.

Conventionally known devices can be used as the dry crushing device, and examples thereof include an attritor, a ball mill, a vibration mill, and a vibration ball mill.
A conventionally known apparatus can also be used as a wet crusher, and examples thereof include batch-type bead mills such as basket mills, continuous-type bead mills of horizontal, vertical, and annular types, sand grinder mills, ball mills, etc. -Stator type homogenizers, ultrasonic dispersion type homogenizers, and wet medium stirring mills (wet crushers) such as an impact crusher that collides fine particles in a dispersion. Examples of the beads used in the wet medium stirring mill include beads made of glass, alumina, zirconia, steel, flint stone, organic resin, and the like.
Water and / or an organic solvent are used as a solvent used when wet-disintegrating the fired body. For example, it is preferable to use water such as pure water, ultrapure water, or ion exchange water. Moreover, although the solid content density | concentration of a baked body crushing dispersion liquid is not restrict | limited especially, For example, it is preferable to exist in the range of 0.3-50 mass%.

In the case of subjecting the fired body to wet disintegration, it is preferable to perform disintegration by wet while maintaining the pH of the solvent at 8.6 to 10.8. When the pH is maintained in this range, the flow potential change amount (ΔPCD) represented by the above formula (1) when cationic colloid titration is performed, and the addition amount (V) of the cationic colloid titration solution in the knick A ceria-based composite hollow fine particle dispersion capable of obtaining a flow potential curve in which the ratio (ΔPCD / V) is −150.0 to −5.0 can finally be obtained more easily.
That is, it is preferable to perform crushing to such an extent that the dispersion liquid of the present invention corresponding to the above-mentioned preferred embodiment is obtained. This is because, as described above, when the dispersion liquid of the present invention corresponding to a preferred embodiment is used as an abrasive, the polishing rate is further improved. The inventors of the present invention have found that the polishing rate is further improved by appropriately thinning the cerium-containing silica layer on the surface of the composite fine particle of the present invention and / or by appropriately exposing child particles to a part of the surface of the composite fine particle. In addition, it is presumed that the falling of ceria particles can be controlled. Furthermore, during disintegration, the silica in the cerium-containing silica layer is dissolved and deposited again, so that a soft and easily soluble silica layer is formed as the outermost layer, and this easily soluble silica layer adheres to the substrate It is estimated that the polishing force is improved by improving the frictional force. In addition, since the cerium-containing silica layer is in a thin or peeled state, it is estimated that child particles are easily detached during polishing. ΔPCD / V is more preferably −145.0 to −10.0, and further preferably −140.0 to −20.0.
In addition, it is the grade which loosens baking powder without passing through a wet disintegration process like the process 2, only dry disintegration and pulverization only, or even if it is a wet disintegration, when it is out of a predetermined pH range, ΔPCD / V is unlikely to be in the range of −150.0 to −5.0, and a soft and easily soluble silica layer is difficult to form.

<Step 3>
In step 3, the crushed and crushed dispersion obtained in step 2 is centrifuged at a relative centrifugal acceleration of 300 G or more, and then the precipitated component is removed to obtain a ceria-based composite hollow fine particle solution.
Specifically, classification is performed by centrifugal separation processing on the fired body crushed and dispersed liquid. The relative centrifugal acceleration in the centrifugation process is set to 300 G or more. After centrifugation, the precipitated components can be removed to obtain a ceria-based composite hollow fine particle dispersion. Although the upper limit of relative centrifugal acceleration is not particularly limited, it is practically used at 10,000 G or less.

  In step 3, it is necessary to provide a centrifugation process that meets the above conditions. When the centrifugal acceleration does not satisfy the above conditions, coarse particles remain in the ceria-based composite hollow particle dispersion, and therefore, when used for polishing applications such as abrasives using the ceria-based composite hollow particle dispersion, It causes scratching.

  In the present invention, the ceria-based composite hollow fine particle dispersion obtained by the above production method can be further dried to obtain ceria-based composite hollow fine particles. The drying method is not particularly limited, and can be dried using, for example, a conventionally known dryer.

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

<Polishing abrasive dispersion>
The liquid containing the dispersion of the present invention can be preferably used as a polishing abrasive dispersion (hereinafter also referred to as “the polishing abrasive dispersion of the present invention”). In particular, it can be suitably used as a polishing abrasive dispersion for polishing a semiconductor substrate on which a SiO ₂ insulating film is formed. Moreover, in order to control polishing performance, a chemical component can be added and it can use suitably as a polishing slurry.

  The polishing abrasive dispersion of the present invention has a high polishing rate when polishing a semiconductor substrate, etc., and has excellent effects such as few scratches (scratches) on the polishing surface and little residual abrasive on the substrate during polishing. ing.

  The abrasive grain dispersion of the present invention contains water and / or an organic solvent as a dispersion solvent. As the dispersion solvent, for example, water such as pure water, ultrapure water, and ion exchange water is preferably used. Further, the polishing abrasive dispersion of the present invention is selected from the group consisting of a polishing accelerator, a surfactant, a heterocyclic compound, a pH adjuster and a pH buffer as an additive for controlling polishing performance. It is suitably used as a polishing slurry by adding species or more.

<Polishing accelerator>
Although it changes with kinds of to-be-polished material to the abrasive grain dispersion liquid of this invention, it can be used as a grinding | polishing slurry by adding a conventionally well-known grinding | polishing promoter as needed. 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, organic acids such as acetic acid, or sodium, potassium, ammonium and amine salts of these acids 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 face.

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

<Surfactant and / or hydrophilic compound>
In order to improve the dispersibility and stability of the abrasive grain dispersion for polishing of the present invention, cationic, anionic, nonionic or amphoteric surfactants or hydrophilic compounds 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 group can be used.

  Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the carboxylate salt include 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 polyoxypropyls. Can pyrene alkyl allyl ether phosphates.

  Aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt as cationic surfactant; carboxybetaine type, sulfobetaine type, as amphoteric surfactant, Aminocarboxylic acid salts, imidazolinium betaines, lecithin, alkylamine oxides can be mentioned.

  Examples of the nonionic surfactant include ether type, ether ester type, ester type and nitrogen type, and as ether type, polyoxyethylene alkyl and alkyl phenyl ether, alkyl allyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene poly Oxypropylene block polymers and polyoxyethylene polyoxypropylene alkyl ethers are mentioned, and as ether ester type, polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitan ester, polyoxyethylene ether of sorbitol ester, as ester type, Polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester , Sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like. In addition, fluorine type surfactant etc. are mentioned.

  As the surfactant, an anionic surfactant or a nonionic 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.

  Furthermore, as other surfactants and hydrophilic compounds, 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 recall, 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, Polyamic acid and its salts such as polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid and its salts; polyvinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein; methyl taurate ammonium salt and methyl taurate 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 3-ethoxypropylsulfonic acid sodium salt and the like; propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide and sulfite Amides such as phenyl amide can be mentioned.

  Note that 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 In the case where the influence of contamination by a metal or a halide is disliked, it is desirable to use an acid or an ammonium salt surfactant.

  When the polishing abrasive dispersion of the present invention contains a surfactant and / or a hydrophilic compound, the content is 0.001 to 10 g in 1 L of the polishing abrasive dispersion as a total amount. Is preferably 0.01 to 5 g, more 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 liter of the abrasive dispersion for polishing, and is preferably 10 g or less from the viewpoint of preventing reduction in the polishing rate. .

  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 abrasive dispersion of the present invention, when a metal is contained in the substrate to be polished, for the purpose of forming a passive layer or dissolution inhibiting layer on the metal and suppressing erosion of the substrate to be polished, A heterocyclic compound may be contained. Here, the "heterocyclic compound" is a compound having a heterocyclic ring containing one or more hetero atoms. 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 heterocyclic compounds, 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 etc. can be mentioned, However, It is not limited to these.

  About content in the case of mix | blending a heterocyclic compound with the abrasive grain dispersion liquid of this invention, it is preferable that it is 0.001-1.0 mass%, and it is 0.001-0.7 mass%. Is more preferable, and 0.002 to 0.4% by mass is more preferable.

<PH adjuster>
An acid or a base and a salt compound thereof may be added to adjust the pH of the polishing composition, as necessary, in order to enhance the effects of the respective additives.

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

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

  Further, as a dispersion solvent for the polishing abrasive dispersion of the present invention, for example, alcohols such as methanol, ethanol, isopropanol, n-butanol, methyl isocarbinol; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, Ketones such as isophorone and cyclohexanone; Amides such as N, N-dimethylformamide and N, N-dimethylacetamide; Diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, 3,4-dihydro-2H-pyran and the like Ethers; glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether; 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butyl ether Glycol ether acetates such as xylethyl acetate; Esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, 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, chlorobenzene; sulfoxides such as dimethyl sulfoxide; N-methyl-2-pyrrolidone, N-octyl Organic solvents such as pyrrolidones such as -2-pyrrolidone can be used. You may mix and use these with water.

  The solid content concentration contained in the polishing abrasive dispersion of the present invention is preferably in the range of 0.3 to 50% by mass. If the solid concentration is too low, the polishing rate may be reduced. 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 the examples and comparative examples will be described. For each example and comparative example, the following measurement results and test results are shown in Tables 1 to 3.

[Analysis of ingredients]
[Measurement of SiO ₂ content]
For SiO ₂ content in the hollow silica fine particle dispersion, as the case of the sodium silicate as a raw material, the hollow silica fine particle dispersion 1000 ° C. ignition loss was carried out were weighed, all but the resulting is SiO _2, containing the The amount was determined. When alkoxysilane was used as the raw material, the silica hollow fine particle dispersion was dried at 150 ° C. for 1 hour and then weighed, and the content was determined assuming that all of the obtained product was SiO ₂ . The content of SiO ₂ obtained here is defined as the solid content (dry amount) of the silica hollow fine particle dispersion. Moreover, the solid content concentration of the silica hollow fine particle dispersion is determined using this value.
In addition, the SiO ₂ content in the ceria-based composite hollow fine particles is reduced to 1000 ° C. in the ceria-based composite hollow fine particle dispersion, and after determining the mass of the solid content, as in the case of Ag to Th described later, Using an ICP plasma emission spectrometer (eg, SPS, SPS5520), the Ce content was measured by the standard addition method to calculate CeO ₂ mass%, and the solid content component other than CeO ₂ was SiO ₂ . The content of SiO ₂ was determined. In addition, the SiO ₂ content, the CeO ₂ content, and the mass part of ceria with respect to 100 parts by mass of silica in the ceria-based composite hollow fine particles were calculated based on the CeO ₂ content and the SiO ₂ content obtained here. Let the total amount of CeO ₂ content and SiO ₂ content obtained here be the solid content amount (dry amount) of the ceria-based composite hollow fine particle dispersion. Moreover, the solid content concentration of the ceria-based composite hollow fine particle dispersion is determined using this value.
In the measurement of the content rates of the specific impurity group 1 and the specific impurity group 2 described below, the content rate of each component with respect to the dry amount was obtained based on the mass of the solid content obtained in this manner.

[Component analysis of ceria-based composite hollow particles or silica hollow particles]
The content of each element is to be measured by the following method.
First, about 1 g of a sample consisting of a ceria-based composite hollow fine particle or a ceria-based composite hollow fine particle dispersion (prepared to have a solid content of 20% by mass) is collected in a platinum dish. Add 3 ml of phosphoric acid, 5 ml of nitric acid and 10 ml of hydrofluoric acid and heat on a sand bath. Once dried, a small amount of water and 50 ml of nitric acid are added and dissolved to make a 100 ml volumetric flask, and water is added to make 100 ml. In this solution, Na and K are measured with an atomic absorption spectrometer (for example, Z-2310, manufactured by Hitachi, Ltd.). Next, the operation of collecting 10 ml of the separated solution in a 20 ml measuring flask from the solution made up to 100 ml is repeated 5 times to obtain 5 10 ml of the separated solution. Then, using this, Ag, Ca, Cr, Cu, Fe, Mg, Ni, Zn, U and Th are measured by a standard addition method using an ICP plasma emission analyzer (for example, SPS 5520 manufactured by SII). Here, a blank is also measured by the same method, and the blank is subtracted and adjusted to obtain measured values for each element.
And based on the mass of solid content calculated | required by the above-mentioned method, the content rate of each component with respect to the amount of dry was calculated | required.

The content of each anion is to be measured by the following method.
<Cl>
Acetone is added to 20 g of a sample consisting of a ceria-based composite hollow fine particle or ceria-based composite hollow fine particle dispersion (solid content adjusted to 20% by mass) to 100 ml, and 5 ml of acetic acid, 0.001 molar sodium chloride is added to this solution. 4 ml of the solution is added, and analysis is performed by a potentiometric titration method (manufactured by Kyoto Electronics: potentiometric titrator AT-610) with a 0.002 molar silver nitrate solution.
As a blank measurement separately, 5 ml of acetic acid and 4 ml of 0.001 molar sodium chloride solution are added to 100 ml of acetone, and the titration amount in the case of titration with a 0.002 molar silver nitrate solution is obtained. It was subtracted from the sample to give a titre of the sample.
And based on the mass of solid content calculated | required by the above-mentioned method, the content rate of each component with respect to the amount of dry was calculated | required.

<SO ₄ >
5 g of a sample composed of ceria-based composite hollow microparticles or a ceria-based composite hollow microparticle dispersion (adjusted to a solid content of 20% by mass) was diluted with water to 100 ml, and 4000 rpm in a centrifuge (HIMAC CT06E manufactured by Hitachi). The solution obtained by centrifuging for 20 minutes to remove the sediment component was analyzed with an ion chromatograph (ICS-1100, manufactured by DIONEX).
Then, based on the weight of the solids obtained by the method described above to determine the content of SO ₄ component to dry weight.

[X-ray diffraction method, measurement of average crystallite diameter]
The ceria-based composite hollow particle dispersion or ceria-based composite hollow particles obtained in Examples and Comparative Examples are dried using a conventionally known dryer, and the obtained powder is pulverized in a mortar for 10 minutes, and X-rays are obtained. An X-ray diffraction pattern was obtained with a diffraction device (RINT1400, manufactured by Rigaku Denki Co., Ltd.), and the crystal type was specified.
Further, the full width at half maximum of the (111) plane (about 2θ = 28 °) near 2θ = 28 ° in the obtained X-ray diffraction pattern is measured by the above-mentioned method, and the average crystallite is obtained according to Scherrer's equation. The diameter was determined.

<Average particle size>
With respect to the ceria-based composite hollow fine particle dispersions obtained in the examples and comparative examples, the average particle size of the particles contained therein was measured by the above-described image analysis method.

<Coarse particle number>
The number of coarse particles (the number of particles having a diameter of 0.51 μm or more) contained in the ceria-based composite hollow fine particle dispersions obtained in Examples and Comparative Examples was measured. The measurement is a method using a conventionally known coarse particle number measuring apparatus as described above.

[Abrasion test method]
Polishing of SiO ₂ film
A polishing abrasive particle dispersion containing the ceria-based composite hollow particle dispersion obtained in each of the examples and the comparative examples was prepared. Here, the solid content concentration was 0.6% by mass and nitric acid was added to adjust the pH to 5.0.
Next, as a substrate to be polished, a SiO ₂ insulating film (thickness 1 μm) substrate prepared by a thermal oxidation method was prepared.
Next, the substrate to be polished is set in a polishing apparatus (NF300, manufactured by Nano Factor Co., Ltd.), and a polishing pad ("IC-1000 / SUBA400 concentric type" manufactured by Nitta Haas) is used. Polishing was performed by supplying an abrasive grain dispersion for polishing at a rotational speed of 90 rpm for 1 minute at a rate of 50 ml / min.
Then, the weight change of the substrate to be polished before and after polishing was determined to calculate the polishing rate.
Further, 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.). The surface roughness is described in Table 3 because the smoothness and the surface roughness are approximately proportional to each other.
In addition, observation of a polishing flaw was performed by observing the insulating film surface using an optical microscope.

Polishing of aluminum hard disks
A polishing abrasive particle dispersion containing the ceria-based composite hollow particle dispersion obtained in each of the examples and the comparative examples was prepared. Here, the solid content concentration was 9% by mass and the pH was adjusted to 2.0 by adding nitric acid.
A substrate for aluminum hard disk is set in a polishing apparatus (NF300, manufactured by Nano Factor Co., Ltd.), and a polishing pad (“Polytex φ12” manufactured by Nitta Haas Co., Ltd.) is used. Polishing is performed by supplying at a rate of 20 ml / min for 5 minutes, and using an ultra-fine defect / visualization macro apparatus (manufactured by VISION PSYTEC, product name: Micro-Max), the entire surface is observed with a Zoom 15, 65.97 cm ² The number of scratches (linear marks) present on the polished substrate surface was counted, summed, and evaluated according to the following criteria.
Number of linear marks Evaluation less than 50 "very small"
50 to less than 80 "less"
80 or more "many"
At least 80 or more and too many to count the total number "※"

  Examples are described below. The term “solid content concentration” simply means the concentration of fine particles dispersed in a solvent regardless of chemical species.

[Preparation process 1]
Preparation of << Silica Hollow Microparticles >> Silica-alumina sol (manufactured by JGC Catalysts and Chemicals, Inc .: USBB-120, average particle diameter 25 nm, SiO ₂ · Al ₂ O ₃ concentration: 20% by weight, Al ₂ O ₃ content in solid content: 27% by weight) 3900 g of pure water is added to 100 g and heated to 98 ° C., while maintaining this temperature, 7,000 g of a 1.5% by weight aqueous solution of sodium silicate as SiO _{2 and} a concentration as Al ₂ O ₃ An aqueous solution of 7,000 g of a 0.5 wt% aqueous solution of sodium aluminate was added over 5 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 50 nm.

Then, 16,740 g of a 1.5% by weight aqueous solution of sodium silicate as SiO ₂ and 5,580 g of a 0.5% by weight aqueous solution of sodium aluminate as concentration of Al ₂ O ₃ are added over 5 hours to add complex oxidation A dispersion of fine particles (secondary particles) was obtained. At this time, the pH of the reaction solution was 12.2.

  Subsequently, after washing with an ultrafiltration membrane to obtain a solid content concentration of 13% by weight, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle dispersion. At this time, the average particle size was 70 nm.

  1,125 g of pure water was added to 500 g of this composite oxide fine particle dispersion, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Subsequently, while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, the aluminum salt dissolved in the ultrafiltration membrane was separated and washed to obtain an aqueous dispersion of silica-based fine particles having a solid content concentration of 20% by weight.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles, 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C., and then ethyl silicate (SiO ₂ concentration of 28% by weight). %) 117 g was added in 5 hours to form a silica coating layer, and the silica-based fine particles were washed with an ultrafiltration membrane while adding 5 L of pure water to form a silica coating layer having a solid content concentration of 20% by weight. A liquid was obtained.

  Next, aqueous ammonia is added to an aqueous dispersion of silica-based fine particles on which a silica coating layer has been formed to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, and then cooled to room temperature. A silica hollow particle dispersion was obtained.

It was 85 nm when the average particle diameter of the silica hollow fine particles contained in the obtained silica hollow fine particle dispersion was measured by the above-described image analysis method.
Further, when the minor axis / major axis ratio of the hollow silica particles was measured by the above-mentioned image analysis method, the number ratio of particles having a minor axis / major axis ratio of 0.80 or less was 32%.
Further, the specific surface area of the silica hollow fine particles was measured by the BET specific surface area measurement method (nitrogen adsorption method) described above, and it was 100 m ² / g.
Moreover, it was 1.2 g / c when the density of the silica hollow fine particles was measured by the above-mentioned method.
Furthermore, the content rates of the specific impurity group 1 and the specific impurity group 2 contained in the silica hollow fine particles were measured by the above-mentioned method. The results are shown in Table 1.

Example 1
Ultrapure water is added to the silica hollow fine particle dispersion obtained as in Preparation Step 1 above, and a dispersion of 6,000 g (SiO ₂ dry 180 g) having a SiO ₂ solid content concentration of 3% by mass (hereinafter also referred to as A liquid). Got.

Next, ion-exchanged water was added to cerium (III) nitrate hexahydrate (manufactured by Kanto Chemical Co., 4N high purity reagent) to obtain 3.0% by mass B liquid in terms of CeO ₂ conversion.

Next, adjust the A solution (6,000 g) to 15 ° C., and while stirring, add 230.0 parts by weight of CeO ₂ to the B solution (13, 803 g, 100 parts by weight of SiO ₂ ). Equivalent) was added over 18 hours. During this time, the liquid temperature was maintained at 15 ° C., 3% ammonia water was added simultaneously with the solution B, and pH 7.5 to 9.5 was maintained to obtain precursor fine particle dispersion. During the addition of solution B, the oxidation-reduction potential was kept at -200 to 100 mV.
And stirring was continued for 4 hours with the liquid temperature of the precursor fine particle dispersion kept at 15 ° C. During the aging, the redox potential was kept at -200 to 100 mV. After ripening, it was allowed to return to room temperature by leaving it in the room, and washing was carried out while replenishing ion-exchanged water with an ultrafiltration membrane. The precursor particle dispersion after washing had a solid content concentration of 5% by mass, a pH of 4.9 (at 25 ° C.), and a conductivity of 47 μs / cm (at 25 ° C.).

  Next, the obtained precursor particle dispersion was dried in a dryer at 100 ° C. for 16 hours, and then fired for 2 hours using a 1050 ° C. muffle furnace to obtain a powder (fired body).

After adding 652 g of ion-exchanged water to 100 g of the powder (baked body) obtained after firing, and further adjusting the pH to 9.0 using a 3% aqueous ammonia solution, acrylic beads of φ 0.3 mm (Shibata Chemical Industry Co., Ltd. Wet pulverization (Kampe Co., Ltd. manufactured batch type table-top sand mill) for 120 minutes. Further, a 3% aqueous ammonia solution was added at regular intervals so as to maintain the suspension pH at the time of disintegration at 9.0.
Then, after crushing, the reaction product was diluted with ion-exchanged water, and the acrylic beads were separated to obtain 1115 g of a crushed crushed and crushed liquid having a solid content concentration of 5% by mass.

  Next, the fired body pulverized dispersion obtained was treated with a centrifugal separator (manufactured by Hitachi Koki Co., Ltd., model number “CR21G”) at a relative acceleration of 1570 G for 1 minute, and the light liquid was recovered. A hollow fine particle dispersion was obtained.

Then, the content rates of the specific impurity group 1 and the specific impurity group 2 in the ceria-based composite hollow particles contained in the obtained ceria-based composite hollow particle dispersion liquid were measured by the above-mentioned method.
The results are shown in Table 2.

In addition, the silica content and ceria content of the ceria-based composite hollow particles contained in the obtained ceria-based composite hollow particle dispersion, the mass part of ceria per 100 parts by mass of silica, the average crystallite diameter of crystalline ceria, child particles The average particle diameter, the standard deviation of the child particles, the coefficient of variation of the child particles, the specific surface area, the density, and the average particle diameter were measured by the methods described above.
The measurement results are shown in Table 3.

Next, a polishing test was conducted using the obtained ceria-based composite hollow fine particle dispersion.
The results are shown in Table 3.

In addition, the ceria composite hollow fine particles contained in the ceria composite hollow fine particle dispersion obtained in Example 1 were observed using SEM and TEM. FIG. 4A shows an SEM image, and FIG. 4B shows a TEM image. As shown in FIG. 4, it was observed that a thin cerium-containing silica layer was present on the outermost surface of the ceria-based composite hollow fine particles and had a hollow structure with voids inside.
In addition, about the ceria type | system | group composite hollow microparticles contained in the ceria type | system | group composite hollow microparticle dispersion obtained in each of the following Examples 2-5, a SEM image and a TEM image are confirmed, and all have a hollow structure. It was confirmed that a ceria-containing silica layer was present on the surface, and child particles (ceria crystal particles) were dispersed and present in the layer.

  The ceria-based composite hollow fine particles contained in the obtained ceria-based composite hollow fine particle dispersion were measured by an X-ray diffraction method. The obtained X-ray diffraction pattern is shown in FIG. As shown in FIG. 5, a sharp Ceriaite crystal pattern was observed in the X-ray diffraction pattern.

Example 2
The firing was performed at 1050 ° C. in Example 1, but the same operation as in Example 1 was performed except that the firing was performed at 940 ° C., and the same evaluation was performed.

  The ceria composite hollow fine particles contained in the ceria composite hollow fine particle dispersion obtained in Example 2 were measured by X-ray diffraction. The obtained X-ray diffraction pattern is shown in FIG. As shown in FIG. 6, a sharp Ceriaite crystal pattern was observed in the X-ray diffraction pattern.

Example 3
In Example 1, baking was performed at 1050 ° C., but the same evaluation as in Example 1 was performed except that the baking was performed at 1140 ° C.

  The ceria composite hollow fine particles contained in the ceria composite hollow fine particle dispersion obtained in Example 3 were measured by the X-ray diffraction method. The obtained X-ray diffraction pattern is shown in FIG. As shown in FIG. 7, a considerably sharp Ceriaite crystal pattern was observed in the X-ray diffraction pattern.

Example 4
In Example 1, solution A (6,000 g) is maintained at 15 ° C., solution B (13,803 g) is added over 18 hours while stirring, while the solution temperature is maintained at 15 ° C., if necessary 3 % Ammonia water was added to keep the pH at 7.5-9.5, but in Example 4, solution A (6,000 g) was kept at 15.degree. C. and stirred here. Solution B (24,000.0 g, corresponding to 400.0 parts by mass of CeO ₂ with respect to 100 parts by mass of SiO ₂ ) is added over 18 hours, and after completion of the addition, aging is carried out at 15 ° C. for 4 hours Did.
Except these, it implemented similarly to Example 1 and performed the same evaluation.

Example 5
In Example 1, solution A (6,000 g) is maintained at 15 ° C., solution B (13,803 g) is added over 18 hours while stirring, while the solution temperature is maintained at 15 ° C., if necessary 3 % Ammonia water was added to keep the pH at 7.5-9.5, but in Example 4, solution A (6,000 g) was kept at 15.degree. C. and stirred here. Solution B (666.7 g, corresponding to 11.1 parts by mass of CeO ₂ with respect to 100 parts by mass of SiO ₂ ) was added over 18 hours, and after completion of the addition, aging was carried out at a liquid temperature of 15 ° C. for 4 hours The
Except these, it implemented similarly to Example 1 and performed the same evaluation.

Comparative Example 1
The same evaluation as in Example 1 was performed using the silica hollow fine particle dispersion obtained in the preparation step 1.

Comparative Example 2
<Preparation of high purity 113 nm particles>
<< Preparation of silica fine particle dispersion (average particle diameter of silica fine particle 63 nm) >>
Mixing the ethanol 12,090g and ethyl orthosilicate 6,363.9G, it was mixed solution a _1.
Then mixed with ultrapure water 6,120g and 29% aqueous ammonia 444.9G, it was mixed solution b _1.
Next, 192.9 g of ultrapure water and 444.9 g of ethanol were mixed to obtain laying 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 complete, after the liquid temperature was aged by holding 3 hours while the 75 ° C., to adjust the solid content concentration, SiO ₂ solid content concentration of 19 mass%, silica fine particles having an average particle size 63nm by the image analysis method 9,646.3 g of a silica sol dispersed in a solvent was obtained.

<< Silica fine particle dispersion (preparation of average particle diameter of silica fine particles: 113 nm >>
Mixing the methanol 2,733.3g and ethyl orthosilicate 1,822.2G, it 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, 922.1 g of silica sol obtained by mixing 59 g of ultrapure water and 1,208.9 g of methanol as a laying water and having silica fine particles having an average particle diameter of 63 nm obtained in the previous step dispersed in a solvent 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. After the addition is completed, the liquid temperature is kept at 65 ° C. for 3 hours and aged, and then concentrated with an outer membrane and a rotary evaporator to adjust the solid content concentration (SiO ₂ solid content concentration) to 19% by mass. A silica-based fine particle dispersion of 3,600 g was obtained.

114 g of cation exchange resin (SK-1BH manufactured by Mitsubishi Chemical Corporation) was gradually added to 1,053 g of the obtained silica-based fine particle dispersion, and the resin was separated by stirring for 30 minutes. The pH at this time was 5.1.
Further, the content of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn, and Zr in the particles contained in the silica-based fine particle dispersion after the treatment with the cation exchange resin (silica dry The content of each component relative to the amount was 1 ppm or less. Further, the contents of U, Th, Cl and SO ₄ were each 5 ppm or less.
Evaluation similar to Example 1 was performed using the silica-based fine particle dispersion obtained as described above.
The silica-based fine particles contained in the silica-based fine particle dispersion used in Comparative Example 2 do not have a hollow structure, but Table 1 shows the measurement results of the average particle diameter, components, and the like.

  Since the ceria-based composite hollow fine particles contained in the dispersion of the present invention do not contain coarse particles, they are low in scratch and have a high polishing rate. Therefore, the polishing abrasive dispersion containing the dispersion of the present invention can be preferably used for polishing the surface of a semiconductor device such as a semiconductor substrate or a wiring substrate. Specifically, it can be preferably used for planarizing a semiconductor substrate on which a silica film is formed.

Claims (6)

A ceria-based composite hollow fine particle dispersion comprising ceria-based composite hollow particles having an average particle diameter of 20 to 400 nm, having the features of the following [1] to [3].
[1] The ceria-based composite hollow particle has a hollow structure having a void in the inside of the cerium-containing silica layer as the outer shell, and child particles mainly composed of crystalline ceria are dispersed in the inside of the cerium-containing silica layer. Being
[2] The ceria-based composite hollow particles should be detected only in the crystalline phase of ceria when subjected to X-ray diffraction.
[3] The ceria-based composite hollow fine particles have an average crystallite diameter of the crystalline ceria of 8 to 30 nm measured by X-ray diffraction. The ceria-based composite hollow fine particle dispersion according to claim 1 or 2, wherein the content ratio of impurities contained in the ceria-based composite hollow fine particles is as shown in the following (a) and (b).
(A) The contents of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr are each 100 ppm or less.
(B) The contents of U, Th, Cl and SO ₄ are each 5 ppm or less.   A polishing abrasive dispersion comprising the ceria-based composite hollow fine particle dispersion according to claim 1.   The polishing abrasive dispersion according to claim 3, wherein the polishing abrasive dispersion is for planarizing a semiconductor substrate on which a silica film is formed. A method for producing a ceria-based composite hollow particle dispersion, comprising the following steps 1 to 3 to obtain the ceria-based composite hollow particle dispersion according to claim 1 or 2.
Step 1: A silica hollow fine particle dispersion in which silica fine particles are dispersed in a solvent is stirred, and the temperature is maintained at 0 to 70 ° C., the pH is set to 7.0 to 11.0, and the oxidation-reduction potential is maintained at −400 to 300 mV. Meanwhile, a step of adding a metal salt of cerium continuously or intermittently to obtain a precursor particle dispersion containing precursor particles.
Step 2: The precursor particle dispersion is dried, calcined at 400 to 1,200 ° C., a solvent is added to the obtained calcined product, and wet crushing is performed in a pH range of 8.6 to 10.8. And a step of obtaining a fired body disintegration dispersion.
Step 3: A step of obtaining a ceria-based composite hollow fine particle dispersion by subjecting the calcined dispersion to a centrifuge at a relative centrifugal acceleration of 300 G or more and subsequently removing a sediment component. 6. The production of a ceria-based composite hollow fine particle dispersion according to claim 5, wherein the content ratio of impurities contained in the silica hollow fine particles in the step 1 is as follows (a) and (b): Method.
(A) The contents of Na, Ag, Ca, Cr, Cu, Fe, K, Mg, Ni, Zn and Zr are each 100 ppm or less.
(B) The contents of U, Th, Cl and SO ₄ are each 5 ppm or less.