JP2006315110A - Abrasive material, manufacturing method and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasive material and a manufacturing method thereof, effectively polishing the surface of a body to be polished without using a polishing pad. <P>SOLUTION: This abrasive material for polishing the surface of a body to be polished is an abrasive material containing composite fine particles having a two-layer structure composed of a base resin particle and an abrasive layer covering the surface thereof. This manufacturing method of the abrasive material includes processes of: (a) dispersing abrasives in a medium having good wettability to the abrasive grains to prepare an abrasive dispersed liquid; (b) dispersing base resin particles in a medium having good wettability to the base resin particles to prepare the base resin particle dispersed liquid; and (c) mixing the abrasive dispersed liquid with the base resin particle dispersed liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abrasive, a method for producing the same, and a polishing method. More specifically, the present invention is an abrasive containing composite fine particles having a two-layer structure of a mother particle and an abrasive layer covering the surface, which can effectively polish the surface of the object to be polished. The present invention relates to a method for efficiently manufacturing this product and a method for effectively polishing the surface of an object to be polished using the above-mentioned abrasive.

Conventionally, in the finishing process of semiconductor substrates and magnetic disk substrates used for electronic equipment parts, loose abrasive polishing methods using various polishing cloths have been adopted, and in order to realize a mirror surface, An elastic polishing cloth such as a nonwoven fabric or a foam is used as a tool.
Such a loose abrasive polishing method is a method in which a polishing cloth is placed on a surface plate as a polishing pad, and polishing is performed while adding abrasive grains between the polishing pad and the object to be polished. Is rotated under pressure to achieve surface polishing with the abrasive grains. Therefore, the polishing pad is placed so that the object to be polished and the surface plate do not come into direct contact with each other to cause scratches. However, for example, a woven fabric has an adverse effect on roughness and waviness. In some cases, non-woven fabrics have problems such as uneven density. In addition, since a load is applied to the polishing cloth, there is a problem that the polishing cloth gradually loses elasticity and becomes hard due to repeated use.

In addition, since the abrasive grains are supplied in a state of being suspended in the polishing liquid, chips and abrasive grains may accumulate on the polishing cloth, resulting in a decrease in polishing efficiency or generation of aggregated particles that may cause scratches. is there. For this reason, the work which grinds the surface of polishing cloth is needed, and the fall of production efficiency is caused by temporary stop of a polishing process. Further, as the size of the object to be polished is increased as in the case of a silicon wafer in recent years, the size of the polishing pad is inevitably increased, and skill is required for the mounting work on the surface plate. For this reason, a harder polishing cloth has been demanded due to the high processing accuracy required for shape in recent precision polishing, and a two-layer polishing cloth in which a hard resin layer and a soft resin layer are superposed has also been proposed. .
On the other hand, as a method of performing mirror surface processing without using a polishing pad, there is float polishing in which a workpiece is lifted from a surface plate using a hydroplane phenomenon and polished in a fluid-supported state. However, in this fluid support polishing, there is a problem that the polishing efficiency is lower than when a conventional polishing cloth is used.

Further, as a polishing method that does not use a polishing pad, an abrasive for polishing the surface of an object to be polished, which is composed of mother particles and ultrafine abrasive particles held on the surface, is disclosed. (For example, refer to Patent Document 1). In the conventional polishing method, polishing is performed with abrasive grains present between a polishing pad placed on a surface plate and an object to be polished. Polishing is performed without holding a polishing pad while holding fine abrasive grains. In this case, the ultrafine abrasive grains are retained on the mother particles in the abrasive during polishing, and even if the ultrafine abrasive grains in the abrasive are exfoliated from a part of the surface of the mother particles during polishing, the mother particles are separated again. The ultrafine abrasive grains adhere to the part that has been polished, and polishing is performed with the ultrafine abrasive grains.
The method using the mother particles disclosed in this publication eliminates the need for a conventional polishing pad and is advantageous in terms of cost because it does not require replacement or correction of the polishing pad.

  However, in the method using carrier particles for holding or adhering abrasive grains instead of such a polishing pad, the carrier particles do not damage the object to be polished by direct contact between the surface plate and the object to be polished. It functions to maintain the distance between the surface plate and the object to be polished, and also acts to rub the abrasive grains in the polishing slurry against the surface of the object to be polished. In such a polishing method, it is considered that the interfacial chemical properties of the carrier particles are involved in the adhesion and retention of the abrasive grains and affect the processing characteristics. In addition, the surface shape such as the roughness and waviness of the surface plate may affect the mobility of the carrier particles, and it is desired to elucidate the factors that affect the processing characteristics for improving the polishing efficiency. Since the abrasive is a consumable product, it is preferable to obtain an effective polishing efficiency with a small amount of use, but it is the actual situation that no satisfactory abrasive has been found yet.

JP 2001-300843 A

  Under such circumstances, the present invention provides an abrasive capable of effectively polishing the surface of an object to be polished without using a polishing pad, and an object of the object to be polished using the abrasive. An object of the present invention is to provide a method for effectively polishing a surface.

As a result of intensive studies to achieve the above object, the present inventor achieved the object with an abrasive containing a composite particle having a two-layer structure composed of a base particle and an abrasive layer covering its surface. It has been found that this abrasive can be efficiently produced by applying a specific process. The present invention has been completed based on such findings.
That is, the present invention
(1) An abrasive for polishing the surface of an object to be polished, comprising a composite particle having a two-layer structure comprising a base particle and an abrasive layer covering the surface,
(2) The abrasive according to (1) above, wherein the composite fine particles are contained in a single dispersion state in the medium,
(3) The abrasive according to (1) or (2) above, wherein the average particle size ratio of the abrasive grains in the abrasive layer to the mother particles is 1/2000 to 1/5,
(4) The abrasive according to any one of (1) to (3) above, wherein the mother particles are resin particles obtained by polymerizing a polymerizable monomer in a solvent,

(5) (a) a step of dispersing abrasive grains in a medium having good wettability to abrasive grains to prepare an abrasive dispersion; (b) a mother in a medium having good wettability to base particles. (1) to (4), characterized by comprising a step of dispersing particles to prepare a mother particle dispersion, and (c) a step of mixing the abrasive dispersion and the mother particle dispersion. A method for producing the abrasive according to any one of the items,
(6) In the step (c), the abrasive dispersion and the mother particle dispersion are each adjusted to a temperature in the range of 0 to 40 ° C. lower than the glass transition temperature of the mother particle, and the medialess type disperser is used. The method for producing an abrasive according to item (5), wherein the operation of mixing is performed,
(7) The method for producing an abrasive according to (6) above, wherein the medialess disperser is a homomixer type, a comb-teeth type or an intermittent jet flow generation type,
(8) The abrasive according to item (6) or (7), wherein the medium in the mother particle dispersion is volatilized when the abrasive dispersion and the mother particle dispersion are mixed in a medialess disperser. Manufacturing method,
(9) The method for producing an abrasive according to the above item (8), wherein the medium in the mother particle dispersion is an alcohol having a boiling point of less than 100 ° C. at normal pressure,
(10) The method for producing an abrasive according to any one of (6) to (9) above, wherein the rotation speed of the medialess disperser is 1000 to 40000 rpm, and (11) the polishing surface of the object to be polished; In addition, the abrasive according to any one of the above (1) to (4) is interposed between the upper surface of the surface plate and the object to be polished and the surface plate are slid relative to each other. A polishing method characterized by
Is to provide.

  According to the present invention, an abrasive containing composite fine particles having a two-layer structure of a mother particle and an abrasive layer covering the surface, which can effectively polish the surface of the object to be polished. And a method for effectively polishing the surface of the object to be polished using the abrasive.

The abrasive of the present invention is an abrasive for polishing the surface of an object to be polished, and includes composite fine particles having a two-layer structure consisting of a base particle and an abrasive layer covering the surface. To do.
The abrasive of the present invention preferably has a form in which the composite fine particles are contained in a single dispersion state in a medium. Here, the single dispersion state indicates a state in which the composite fine particles are dispersed individually without aggregation.
Thus, when polishing the surface of an object to be polished using an abrasive in which composite fine particles having a two-layer structure of a mother particle and an abrasive layer are monodispersed in a medium, a surface plate and an object to be polished are used. The composite fine particles act as countless micropads with the body. Since the abrasive grains coated on the surface of the composite fine particles come into contact with the object to be polished, the polishing efficiency is lowered when the composite fine particles are not dispersed in the abrasive. This dispersibility varies depending on various characteristics such as hydrogen ion concentration and viscosity of the abrasive medium, but strongly depends on the affinity between the composite fine particles and the abrasive medium, and in particular, the dispersion of the composite fine particles when dispersed in the abrasive medium. It was found that the effect on sex was strong. That is, it is important to produce a composite fine particle composed of a base particle and abrasive grains whose surface is uniformly coated, and it is also important that the composite fine particle is monodispersed.

  Next, the composite fine particles used for the abrasive of the present invention will be described. As long as the composite fine particles are supplied between the surface plate and the object to be polished in a state where the mother particles and the surface thereof are coated with abrasive grains, and the object to be polished is polished by the coated abrasive grains The shape and size are not particularly limited. The mother particle is preferably an organic polymer compound in terms of excellent transportability and polishing efficiency of abrasive grains as a micropad. As the mother particles, resin particles obtained by polymerizing a polymerizable monomer in a solvent can be preferably used. The type of the polymerizable monomer and the polymerization solvent is not particularly limited, but the solvent for polymerization is selected according to the type of the polymerizable monomer to be used. Is good. This is because, when this polymerization solvent is not preferable as an abrasive medium, it can be handled by another medium instead of the polymerization solvent after polymerization. The polymerization method is not particularly limited. For example, addition polymerization by repeated addition, condensation polymerization by repeated condensation, ring-opening polymerization in which a monomer having a cyclic structure opens a ring, emulsion polymerization, suspension polymerization, Any of dispersion polymerization, coordination polymerization, photopolymerization, radiation polymerization, plasma polymerization, plasma initiated polymerization, group transfer polymerization and the like may be used. The reaction mechanism may be any of radical polymerization, cationic polymerization, anionic polymerization, and may be any of a homopolymer, a random copolymer, a block copolymer, a graft copolymer, Furthermore, these high molecular polymers may have intramolecular crosslinking.

As the organic polymer compound constituting the mother particle, from the viewpoint of abrasive retention and dispersibility, polyurethane, polyamide, polyimide, polyester, polyethylene, polystyrene, crosslinked polystyrene, polypropylene, polyvinyl chloride, polyvinylidene chloride, ABS resin, Polystyrene / AS resin, acrylic resin, methacrylic resin, phenol resin, urea / melamine resin, silicone resin, epoxy resin, polyacetal resin, benzoguanamine resin, polycarbonate, polyphenylene ether, polyphenylene sulfide, polysulfone, polyarylate, polyetherimide, polyether The mixture and composition which consist of 1 type (s) or 2 or more types chosen from sulfone, polyether ketone, etc. can be mentioned.
The mother particle may be a composite of an organic polymer compound and an inorganic compound. For example, the above organic polymer compound is used as a nucleus, and the inorganic compound is chemically or physically supported, adsorbed or chemically bonded to the surface of the organic polymer compound, and the organic polymer compound is synthesized in the presence of the inorganic compound. The organic polymer compound includes an inorganic compound, the inorganic compound is used as a core, the organic polymer compound thin film is coated on the surface, or a graft chain is formed by chemical bonding. It may be modified. Furthermore, the organic polymer compound itself having a hollow part, or a substance in which a gas or liquid other than air is sealed in the hollow part may be used. As an inorganic compound used as such a composite, one or more microbeads such as carbon microbeads, glass beads, and mesocarbon beads can be used in combination. Microbeads such as carbon microbeads, glass beads, and mesocarbon beads are commercially available from Osaka Gas Co., Ltd., Symicon Composite, and the like.

More specific mother particles include the following. For example, it is obtained by polymerizing an aromatic monomer such as styrene in a hydrophilic solvent containing an inorganic dispersant at a temperature of about 60 to 100 ° C. with stirring using an organic peroxide as a polymerization initiator. Resin particles.
In this polymerization, a dispersion stabilizer can be used. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate. Metal oxides such as aluminum oxide and titanium oxide; metal hydroxides such as aluminum hydroxide, magnesium hydroxide and ferric hydroxide; water-soluble polymer compounds such as polyvinyl alcohol, methylcellulose and gelatin; anionic surface activity Agents, nonionic surfactants, amphoteric surfactants and the like.
Further, in a hydrophilic solvent, (meth) acrylic acid ester such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, with organic peroxide as a polymerization initiator and 50 to 50 with stirring. There are resin particles obtained by polymerization at a temperature of about 100 ° C.
Examples of the hydrophilic solvent include pure water, ion exchange water, methanol, ethanol, butanol, propanol, t-butanol and other alcohols having 1 to 12 carbon atoms, ethylene glycol, propylene glycol. Etc. can be used.

Examples of mother particles composed of a composite of an organic polymer compound and an inorganic compound include fine particles obtained as follows.
1 to 15 parts by mass of silica having a pore with a specific surface area of 50 to 400 m ² / g by BET method and 0.01 to 5 curing catalyst with respect to 100 parts by mass (equivalent to resin solid content) of an emulsion of guanamine-based resin. There are organic polymer fine particles obtained by adding a part by mass and proceeding the curing reaction of the resin in an emulsified state in which fine particle silica and a curing catalyst coexist, thereby obtaining a cured product from an aqueous medium. The resin hardened in the emulsified state and separated from the aqueous medium by filtration or centrifugation is a lump, but is loosened to a fine powder with a slight force. Moreover, since it polymerized in the presence of silica and a curing catalyst, coarse particles are not contained and the dispersibility is excellent.

  Further, benzoguanamine, or a mixture of 100 to 50 parts by mass of benzoguanamine and 0 to 50 parts by mass of melamine and formaldehyde at a ratio of 1.2 to 3.5 mol with respect to 1 mol of benzoguanamine or the mixture, pH 5 to 10 And a soluble fusible resin having a methanol miscibility in the range of 0 to 150%, and then charged into a protective colloid aqueous solution under stirring, at least at a temperature in the range of 40 to 60 ° C. After holding for 1 hour, a cured product obtained by curing at normal temperature or under a pressure in the range of 60 to 200 ° C. can also be used. The cured product obtained by such a method is preferable in that it has a uniform fine particle diameter and excellent bonding and holding characteristics with the abrasive grains. The methanol miscibility was required to dissolve 2 g of a reaction product of benzoguanamine or a mixture of benzoguanamine and melamine and formaldehyde in 5 g of methanol and add water dropwise while maintaining the temperature at 25 ° C. to cause cloudiness. It is a numerical value obtained by multiplying the ratio of the mass of water and the mass of the reaction product by 100. Examples of the protective colloid include polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, polyacrylic acid, and water-soluble polyacrylate.

  The mother particles used in the present invention function as spacers to prevent scratches due to direct contact between the surface plate and the object to be polished, and serve as particles that hold and transport abrasive grains to the processing region and are uniform in the processing region. It is necessary to stay for a certain time so that dispersion and polishing can be continued. In order to ensure such various characteristics, the average particle diameter of the mother particles is preferably 0.1 to 30 μm, more preferably 0.5 to 20 μm, particularly preferably 1 when the shape is a true sphere. ~ 15 μm. In order to obtain polymer particles in such a range, it can be prepared by appropriately selecting the blending amount and temperature of the polymerization initiator. When the particle is a polymer compound, the surface thereof may have a microprojection made of an organic polymer chain. In the present invention, in order to ensure the function of the mother particles as a spacer, the average size of the mother particles in the case of an indefinite shape is calculated as the average of the shortest lengths as the average particle diameter. The molecular weight of the polymer is not particularly limited as long as the base particles are in the above range.

In the composite fine particles, the abrasive grains constituting the abrasive grain layer coated on the surface of the base particles are not particularly limited as long as they can polish the surface of the object to be polished. For example, colloidal silica, silica, alumina, A mixture of one or more selected from ceria, titania, zirconia, silicon nitride, silicon carbide, manganese oxide and the like can be used.
The average particle size of the abrasive grains is generally 0.001 to 3 μm, preferably 0.005 to 2 μm, more preferably 0.01 to 1 μm, although it depends on the average particle size of the mother particles. When the average grain size of the abrasive grains is in the range of 0.001 to 3 μm, the generation of scratches on the polished surface is suppressed and the polishing efficiency is good. The average particle size ratio of the abrasive grains to the base particles is preferably 1/2000 to 1/5, more preferably 1/1500 to 1/5, and still more preferably 1/1000 to 1/10.
The abrasive grains polish the surface of the object to be polished, and need to be coated on the surface of the mother particles during the polishing process. In this case, the abrasive particles that have been separated from a part of the surface of the mother particles during polishing may adhere to the portions where the mother particles have been separated again. The bond between the mother particles and the abrasive grains may be either chemical bond or physical bond, and the abrasive grains may be appropriately selected from those suitable for bonding with the mother particles used. For example, when polystyrene, crosslinked polystyrene, acrylic resin, methacrylic resin, and benzoguanane resin are used as mother particles, colloidal silica, silica, ceria, and alumina are preferably used as abrasive grains.

The method for coating the surface of the mother particles with the abrasive layer will be described in detail in the description of the method for producing an abrasive described later.
In the composite fine particles, the mechanical strength at 10% displacement measured at a compression rate of 0.27 g / sec is preferably 1 to 50 MPa. When the mechanical strength of the composite fine particles is low, deformation by pressurization is easy, and the deformation increases the contact area between the object to be polished and the composite fine particles, and the polishing efficiency increases exponentially. However, if the mechanical strength is too low, it becomes difficult to provide an action as a micropad that secures the distance between the surface plate and the object to be polished, and scratches may occur on the object to be polished. Therefore, the mechanical strength is preferably 1 MPa or more. Moreover, if it is 50 Mpa or less, the deformation | transformation of the mother particle on the pressurization conditions at the time of grinding | polishing will be easy, the increase in a contact area by a deformation | transformation with a to-be-polished body will arise, and polishing efficiency can be improved. Moreover, it is possible to suppress the occurrence of scratches on the object to be polished. This mechanical strength is more preferably 1 to 40 MPa, particularly preferably 1 to 30 MPa.
In the present invention, the mechanical strength is measured by a micro compression tester, and as such a device, there is a Shimadzu micro compression tester MCTM / MCTE series. When the sample is particles, the strength when displaced at a compression rate of 0.27 g / sec is calculated. The reason why the compression speed was set to 0.27 g / sec is that a condition with a relatively high compression speed was selected because the abrasive was quickly brought into contact with the object to be polished in polishing. The measurement principle is that a sample is placed between the upper presser indenter (standard flat indenter with a diameter of 50 μm) and the lower presser plate, and one particle of the sample is pressed at a constant increase rate by electromagnetic force. Is calculated according to the following formula by measuring the amount of displacement of the sample at this time.
St = 2.8P / πd ²
[St: Mechanical strength (MPa), P: Load at 10% displacement (N), d: Particle diameter (mm)]

The abrasive of the present invention may contain a pH adjuster, a viscosity adjuster, a dispersant, a flocculant, a surfactant, and the like as long as the effects of the present invention are not impaired.
Next, the manufacturing method of the abrasive | polishing agent of this invention is demonstrated.
The manufacturing method of the abrasive | polishing agent of this invention consists of (a) the process which disperse | distributes an abrasive grain in the medium with good wettability with respect to an abrasive grain, and prepares an abrasive dispersion, (b) wets with respect to a mother particle. And a step of preparing a mother particle dispersion by dispersing the mother particles in a good medium, and (c) mixing the abrasive dispersion and the mother particle dispersion.
In the manufacturing method of the abrasive | polishing agent of this invention, the method of making composite microparticles | fine-particles by the interface parent deposition method and the mechanical method is used. Specifically, a mechanical force is applied while mixing the base particles and smaller abrasive grains. The surface of the mother particles is obtained by compressing the mother particles uniformly with a medium having good wettability to the mother particles and a medium having good wettability to the abrasive grains, preferably by a mediumless disperser according to temperature and rotation speed. Is coated with an abrasive layer, and composite fine particles are formed while the base particle medium is volatilized by the heating temperature, and a monodispersed abrasive is obtained.

More specifically, the abrasive dispersion and the mother particle dispersion are each adjusted to a temperature in the range of 0 to 40 ° C. lower than the glass transition temperature of the mother particles, and mixed with a medialess disperser. At this time, the rotation speed of the medialess disperser is preferably 1000 to 40000 rpm, more preferably 3000 to 20000 rpm, and particularly preferably 3000 to 10,000 rpm. If the rotational speed is in the range of 1000 to 40000 rpm, the shear force between the mother particles and the abrasive grains is appropriate, and the abrasive grain layer has a good covering force on the mother particle surface while suppressing deformation of the mother particles. Is formed. It is important that the medium in the mother particle dispersion volatilizes during this mixing step. As such a medium, alcohols having a boiling point of less than 100 ° C. at normal pressure are preferable.
Moreover, when the temperature at the time of mixing with a medialess disperser is 0 to 40 ° C. lower than the glass transition temperature (Tg) of the mother particles, the mother particles are not easily fused with each other, and the abrasive layer is formed on the mother particle surface. Is well coated.
As the medialess disperser, a homomixer type, a comb tooth type, an intermittent jet flow generation type, or the like can be used.
The homomixer type is composed of a rotating body that rotates at a high speed and a stationary ring arranged so as to surround the rotating body, and the base particles and abrasive grains are subjected to a shearing force due to a velocity gradient through the gap.

The comb-teeth type includes a comb-teeth type rotating body that rotates at high speed and a comb-teeth type fixed ring. The mother particles and abrasive grains are of the type that generates cavitation due to pressure fluctuations due to the effect of receiving a shearing force in the gap when passing from the inside to the outside as the rotor rotates and the displacement of the slit portion.
The intermittent jet flow generation type is composed of a rotating body rotating at high speed and a screen having several tens of slits arranged with a minute gap. The speed is increased by passing the mother particles and the abrasive grains through the screen slit, an intermittent jet flow is formed on the processed material in the tank, and a shearing force between the processed materials is generated at the speed interface.
In addition, the medium for abrasive | polishing agent, ie, the medium in an abrasive grain dispersion liquid, is used in order to make the coupling | bonding of an abrasive grain and a mother particle easy in the abrasive | polishing agent of this invention, or an improvement of a grinding | polishing effect. Such an abrasive medium is preferably a hydrophilic medium. In the present invention, pure water and ion-exchanged water are preferable from the viewpoints of wettability to abrasive grains and economical and environmental burdens. However, depending on the characteristics of the object to be polished, it can be appropriately selected according to the type of base particles used, the type of abrasive grains, and the like.

In addition, as a medium used for the mother particle dispersion, the solubility of the mother particles is lower than that of pure water, and in consideration of wettability and boiling point less than 100 ° C., those having 1 to 12 carbon atoms such as methanol, ethanol, butanol and the like. Alcohols which may have a branch are mentioned. As the hydrophobic medium, mineral oil, vegetable oil, silicone oil and other oils can be used. In the present invention, these media may be used alone or in combination of two or more. This medium can be adjusted to an optimal hydrogen ion concentration according to the characteristics of both to facilitate the bonding of the particles and abrasive grains, or can be adjusted to an optimal viscosity to improve the dispersibility of both. .
In the method of the present invention, the medium for the base particles may be an amount in which the base particles are monodispersed in the wettable medium, and the amount of the base particle and the amount of the wettable medium for the abrasive grains. The total amount is not limited by the amount of medium when handling the mother particles, and an optimum amount can be selected as an abrasive. As the amount of the abrasive medium used, the optimum range varies depending on the type of the mother particles, but generally 1 to 300 mass times, more preferably 5 to 80 mass times the total amount of the mother particles and abrasive grains. It is. If the amount of the abrasive medium used is in the range of 1 to 300 times by mass, good polishing efficiency can be exhibited.

The present invention is characterized in that the composite fine particles are handled in the presence of a medium. However, since the preferred mother particles are particles obtained by polymerizing a polymerizable monomer in a solvent, the mother particles are hydrophilic. Depending on whether it is hydrophobic, there are optimal combinations with abrasive media. That is, in general, when the mother particles are hydrophilic, they are easily dispersed in the hydrophilic dispersion medium, but are difficult to disperse in the hydrophobic dispersion medium. Therefore, in the present invention, the mother particles are hydrophobic and are dispersed in an alcohol medium and volatilized in the process. This method is particularly effective when the abrasive medium is a hydrophilic medium. For example, when the mother particle is a hydrophobic organic polymer compound such as polystyrene, crosslinked polystyrene, uncrosslinked methacrylic resin, crosslinked methacrylic resin, uncrosslinked acrylic resin, crosslinked acrylic resin, polyethylene, etc. It is preferable to use a hydrophilic medium such as pure water, ion-exchanged water, alcohols such as methanol and ethanol.
In the method of the present invention, the mixing ratio of the mother particles and the abrasive grains when mixing the abrasive dispersion and the mother particle dispersion is preferably 10 to 2000 parts by mass of the abrasive grains with respect to 100 parts by mass of the mother particles. More preferably, it is good to mix in the ratio of 50-1000 mass parts, Most preferably, it is 50-500 mass parts. When the mixing ratio of the abrasive grains is in the range of 10 to 2000 parts by mass, the abrasive grains are efficiently held on the surface of the mother particles and the polishing efficiency is also improved. In addition, when the abrasive grains already contain a solvent such as colloidal silica, the blending amount of the abrasive grains is calculated by using the silica amount in the colloidal silica as the blending amount of the abrasive grains.

Next, the polishing method of the present invention will be described. In the polishing method of the present invention, the polishing object of the present invention is interposed between the polishing surface of the object to be polished and the upper surface of the surface plate, and the object to be polished and the surface plate are relatively slid. It is made to move.
In the polishing method of the present invention, a predetermined amount of the abrasive is supplied between a surface plate provided in a polishing machine and the object to be polished, and the abrasive grains contained in the abrasive are brought into contact with the object to be polished. When the polishing body is rotated, the surface thereof is polished by the relative movement between the abrasive grains and the object to be polished.
If the polishing machine has a surface plate and is provided with means for supplying an abrasive and rotating means for the object to be polished, the size of the surface plate can be appropriately selected according to the size of the object to be polished.
The surface plate is preferably made of metal such as copper or tin, glass, ceramic or plastic having good flatness. The shape of the surface plate is not limited to a flat surface, and may be a curved surface, a spherical surface, or an uneven surface. By using such a surface plate, a conventional urethane-based polishing pad becomes unnecessary, and flatness and micro waviness are improved.

The object to be polished is in contact with the abrasive grains while rotating on the polishing agent. In the present invention, the object to be polished may be normally rotated at a known rotation speed, depending on the mother particles, the abrasive grains, the material of the object to be polished, and the like. It can be selected appropriately.
Moreover, although a to-be-polished body can select a processing pressure suitably according to the kind and size of a mother particle or an abrasive grain, it is preferable that it is 5-100 kPa in this invention, More preferably, it is 10-70 kPa. is there.
Also, the amount of abrasive supplied can be appropriately selected according to the size of the surface plate, and the stirring force of the abrasive when supplying to the polishing step is also appropriately determined depending on the type and amount of the base particles and abrasive grains used. You can choose. Specifically, the supply amount of the abrasive onto the surface plate is usually 1 to 100 ml / min, and preferably 10 to 50 ml / min. Further, when lapping the object to be polished while rotating the surface plate at a predetermined rotation speed, the predetermined rotation speed is usually 10 to 500 rpm, and preferably 20 to 200 rpm.
The polishing method of the present invention is excellent in mirror polishing of the surface particularly when a silicon wafer, crystal, glass, sapphire or the like is used as an object to be polished.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Production Example 1
An oil phase was obtained by adding 2 parts by weight of 2,2′-azobis- (2,4-dimethylvaleronitrile) to 100 parts by weight of styrene and mixing them well. Subsequently, 10 parts by mass of tertiary calcium phosphate as a dispersion stabilizer was added to 380 parts by mass of ion-exchanged water in a 5-liter four-necked separable flask equipped with a stirrer, a reflux condenser and a thermometer, and phosphoric acid was added with hydrochloric acid. An aqueous phase was obtained by dissolving calcium. The oil phase was added to this aqueous phase, and calcium phosphate was precipitated with an alkaline aqueous solution, and then mixed well to form a suspension. Furthermore, this suspension was stirred and granulated using a medialess stirrer (“Clearmix 15S” manufactured by M Technique Co., Ltd.) at a rotational speed of 10,000 times per minute, and further at 60 ° C. for 6 hours and then 80 A polymerization reaction was performed in a nitrogen atmosphere at 2 ° C. for 2 hours to obtain an aqueous dispersion.
Subsequently, the suspension was subjected to solid-liquid separation, washed with dilute hydrochloric acid and water with ion exchange water, and sufficiently dried to obtain resin particles. The Tg of the resin particles was 92 ° C.
As a result of measuring the average particle size of the obtained resin particles with a particle size distribution measuring apparatus (Beckman Coulter, Inc), the average particle size was 10.5 μm. % Were mixed to fully wet the particle surface.

Production Example 2
An oil phase was obtained by adding 2 parts by mass of 2,2′-azobis- (2,4-dimethylvaleronitrile) to 100 parts by mass of methyl methacrylate and thoroughly mixing them. Subsequently, 10 parts by mass of tertiary calcium phosphate as a dispersion stabilizer was added to 380 parts by mass of ion-exchanged water in a 5-liter four-necked separable flask equipped with a stirrer, a reflux condenser and a thermometer, and phosphoric acid was added with hydrochloric acid. An aqueous phase was obtained by dissolving calcium. The oil phase was added to this aqueous phase, and calcium phosphate was precipitated with an alkaline aqueous solution, and then mixed well to form a suspension. Furthermore, this suspension was stirred and granulated using a medialess stirrer (“Clearmix 15S” manufactured by M Technique Co., Ltd.) at a rotational speed of 10,000 times per minute, and further at 60 ° C. for 6 hours and then 80 A polymerization reaction was performed in a nitrogen atmosphere at 2 ° C. for 2 hours to obtain an aqueous dispersion.
Subsequently, the suspension was subjected to solid-liquid separation, washed with dilute hydrochloric acid and water with ion exchange water, and sufficiently dried to obtain resin particles. The Tg of the resin particles was 110 ° C.
As a result of measuring the average particle size of the obtained resin particles with a particle size distribution measuring apparatus (Beckman Coulter, Inc.), the average particle size was 9.5 μm. % Were mixed to fully wet the particle surface.
Production Example 3
In Production Example 2, resin particles were obtained in the same manner as in Production Example 2 except that ethanol was not mixed into the resin particles.

Example 1
Resin particles mixed with 1% by mass of ethanol obtained in Production Example 1 were used as a mother particle dispersion. On the other hand, cerium oxide powder (manufactured by Yushiro Chemical Co., Ltd., trade name “Yushiron Tech CEP10”, average particle size 1.0 μm) is used as abrasive grains, and water is used as a medium. A dispersion was prepared.
Next, a medialess stirrer “Clearmix 15S” (described above) is used so that the abrasive particle dispersion and the mother particle dispersion have a mother particle concentration of 2.5 mass% and an abrasive particle concentration of 5 mass%. The mixture was mixed at 70 ° C. for 30 minutes at 10,000 rpm to prepare an abrasive (a dispersion of composite fine particles in which the surface of the mother particles was coated with abrasive grains). The state where the abrasive grains covered the surface of the mother particles was confirmed by observation with a scanning electron microscope (SEM). In addition, when measured with the pH meter, pH of this abrasive | polishing agent was 5.6.
The abrasive was tested for polishing a 4-inch silicon wafer using a single-side polishing machine (trade name “SPL-15” manufactured by Okamoto Machine Tool Co., Ltd.).
As the tool plate, glass having a surface roughness Ra (arithmetic mean roughness) of 2.5 μm was used. The rotation speed of the silicon wafer and the surface plate was 60 rpm, the supply amount of the abrasive was 25 ml / min, and polishing was performed for 20 minutes.
After completion of polishing, the substrate was washed with pure water, the increase / decrease in mass before and after polishing was measured as a removal amount and evaluated as polishing efficiency, and the presence or absence of scratches was evaluated visually. Further, the mechanical strength of the composite fine particles was measured by a Shimadzu micro compression tester MCTM / MCTE series. The results are shown in Table 1.

Example 2
In Example 1, the same operation as in Example 1 was performed except that the resin particles mixed with 1% by mass of ethanol obtained in Production Example 2 were used as the mother particle dispersion. The results are shown in Table 1.
In addition, the obtained abrasive | polishing agent was pH 5.6, and the state in which the abrasive grain had coat | covered the mother particle surface was confirmed by SEM observation.
Comparative Example 1
In Example 1, the same operation as in Example 1 was performed except that the resin particles (mother particles) not mixed with ethanol obtained in Production Example 3 were used instead of the mother particle dispersion. The results are shown in Table 1.
The obtained abrasive had a pH of 5.6, and SEM observation confirmed that the mother particles were agglomerated and that the abrasive grains did not uniformly cover the surface of the mother particles.

  The polishing agent of the present invention includes composite fine particles having a two-layer structure of a base particle and an abrasive layer covering the surface thereof. For example, the surface of an object to be polished such as silicon wafer, crystal, glass, sapphire is effective. Thus, mirror polishing can be performed.

Claims (11)

  A polishing agent for polishing the surface of an object to be polished, comprising a composite fine particle having a two-layer structure comprising a mother particle and an abrasive layer covering the surface.   The abrasive | polishing agent of Claim 1 formed by containing a composite fine particle in a single dispersion state in a medium.   The abrasive | polishing agent of Claim 1 or 2 whose average particle diameter ratio of the abrasive grain in an abrasive grain layer with respect to a base particle is 1 / 2000-1 / 5.   The abrasive according to any one of claims 1 to 3, wherein the mother particles are resin particles obtained by polymerizing a polymerizable monomer in a solvent.   (A) A process of preparing an abrasive dispersion by dispersing abrasive grains in a medium having good wettability to abrasive grains; (b) Dispersing mother particles in a medium having good wettability to mother grains. 5. The method according to claim 1, further comprising a step of preparing a mother particle dispersion, and (c) a step of mixing the abrasive dispersion and the mother particle dispersion. A method for producing an abrasive.   In step (c), the abrasive dispersion and the mother particle dispersion are each adjusted to a temperature in the range of 0 to 40 ° C. lower than the glass transition temperature of the mother particles, and mixed with a medialess disperser. The manufacturing method of the abrasive | polishing agent of Claim 5 which performs.   The method for producing an abrasive according to claim 6, wherein the medialess disperser is of a homomixer type, a comb tooth type, or an intermittent jet flow generation type.   The method for producing an abrasive according to claim 6 or 7, wherein the medium in the mother particle dispersion volatilizes when the abrasive dispersion and the mother particle dispersion are mixed with a medialess disperser.   The method for producing an abrasive according to claim 8, wherein the medium in the mother particle dispersion is an alcohol having a boiling point of less than 100 ° C at normal pressure.   The method for producing an abrasive according to any one of claims 6 to 9, wherein the rotation speed of the medialess disperser is 1000 to 40000 rpm. The abrasive according to any one of claims 1 to 4 is interposed between the polishing surface of the object to be polished and the upper surface of the surface plate, and the object to be polished and the surface plate are relatively slid. A polishing method, characterized by comprising: