JP4811586B2 - Chemical mechanical polishing aqueous dispersion, method for producing the same, and chemical mechanical polishing method - Google Patents

Description

  The present invention relates to a method for producing a chemical mechanical polishing aqueous dispersion, a chemical mechanical polishing aqueous dispersion, and a chemical mechanical polishing method. More specifically, a method for producing a chemical mechanical polishing aqueous dispersion that is particularly useful in chemical mechanical polishing of an insulating film in a semiconductor device manufacturing process, a chemical mechanical polishing aqueous dispersion obtained by the manufacturing method, and the chemical mechanical polishing water The present invention relates to a chemical mechanical polishing method using a system dispersion.

As the degree of integration of semiconductor devices increases and the number of wiring layers increases, the storage capacity of memory devices has increased dramatically. This is supported by the progress of miniaturization of processing technology, but the chip size becomes large despite the multilayer wiring, etc., and the number of processes required for manufacturing the chip increases with miniaturization, The cost of the chip is incurred. Under such circumstances, chemical mechanical polishing technology has been introduced and widely used for polishing processed films and the like. By applying this chemical mechanical polishing technique, many miniaturization techniques such as planarization have been realized.
As such a miniaturization technique, for example, a so-called STI technique, known as miniaturization element isolation (Shallow Trench Isolation), is known. In this STI technique, chemical mechanical polishing is performed in order to remove an extra insulating layer formed on the wafer substrate. In this chemical mechanical polishing step, the flatness of the surface to be polished is important, and therefore various types of polishing agents have been studied.

For example, in Patent Documents 1 and 2, in an STI chemical mechanical polishing process, by using an aqueous dispersion using ceria as polishing abrasive grains, a surface to be polished has a high polishing rate and relatively few polishing flaws. It is disclosed that it can be obtained.
In recent years, as the number of semiconductor elements has been further increased in the number of layers and the definition has been increased, further improvement in the yield and throughput of the semiconductor elements has been required. Along with this, there is a growing demand for high-speed polishing with substantially no polishing scratches on the surface to be polished after the chemical mechanical polishing step.
There are reports that surfactants such as chitosan acetate, dodecylamine, and polyvinylpyrrolidone are effective in reducing polishing scratches on the surface to be polished (see Patent Documents 3 to 5). However, according to these techniques, although an effect is seen in reducing polishing scratches, the polishing rate is lowered, and an improvement in throughput has not yet been achieved.

By the way, in the chemical mechanical polishing process as described above, it is possible to save the semiconductor material, the aqueous dispersion for chemical mechanical polishing, and the like by ending the polishing process immediately after the excess portion on the polished surface is removed by polishing. It is also an important item that leads to an improvement in product throughput. In the past, the polishing end point was determined based on empirically obtained time. However, the time required for polishing varies depending on the aqueous dispersion and polishing apparatus used for polishing, and it is very inefficient to empirically obtain the polishing time from each of the polishing under various different conditions.
On the other hand, a method for detecting the polishing end point by tracking the current value of the motor that rotates the polishing platen of the chemical mechanical polishing apparatus has been proposed (see Patent Document 6). In this method, the initial step on the surface to be polished is eliminated by the progress of polishing, and the current change due to flattening is taken as the end point, but according to this method, the true end point, that is, it should be removed by polishing. It is in principle impossible to detect when the material has been completely removed. In addition, research is being conducted on an optical end point detection apparatus and method using an optical method capable of directly observing the state of the surface to be polished (see Patent Documents 7 and 8). However, when the optical end point detection method is applied to the removal of the insulating layer in the chemical mechanical polishing process of STI, there is a problem that the end point detection is not reliable.
JP-A-5-326469 JP-A-9-270402 JP 2000-109809 A JP 2001-7061 A JP 2001-185514 A JP 2002-203819 A Japanese Patent Laid-Open No. 9-7985 JP 2000-326220 A JP 60-235631 A

  The present invention has been made in view of the above circumstances, and the object thereof is chemical mechanical polishing capable of polishing at a high speed with substantially no scratches on the surface to be polished, particularly in the STI chemical mechanical polishing process. An object of the present invention is to provide a method for producing an aqueous dispersion, a chemical mechanical polishing aqueous dispersion obtained by the production method, and a chemical mechanical polishing method using the chemical mechanical polishing aqueous dispersion.

According to the present invention, the above object of the present invention is as follows. First, (A) an aqueous dispersion containing 100 parts by weight of inorganic particles containing ceria, (B) 0.05 to 5 parts by weight of polyorganosiloxane, (C This is achieved by a method for producing an aqueous dispersion for chemical mechanical polishing comprising the step of sequentially adding 5) to 100 parts by weight of cationic organic polymer particles and (D) 5 to 100 parts by weight of an anionic water-soluble compound.
The above object of the present invention is secondly achieved by the chemical mechanical polishing aqueous dispersion produced by the above method, and thirdly, chemical mechanical polishing for polishing an insulating film using the chemical mechanical polishing aqueous dispersion. Achieved by the method.

The method for producing an aqueous dispersion for chemical mechanical polishing according to the present invention comprises (A) an aqueous dispersion containing inorganic particles containing ceria, (B) polyorganosiloxane, (C) cationic organic polymer particles, and (D ) It includes a step of sequentially adding an anionic water-soluble compound. Here, “added sequentially” means that (A) the components (B) to (D) are added to the aqueous dispersion in the order of the components (B), (C), and (D). To do.
Hereinafter, each component used for the manufacturing method of this invention is demonstrated.
(A) Aqueous Dispersion Containing Inorganic Particles Containing Ceria Inorganic particles containing ceria used in the method for producing a chemical mechanical polishing aqueous dispersion of the present invention (hereinafter, sometimes simply referred to as “inorganic particles”) May consist of ceria alone or may be a mixture of ceria and other inorganic particles. Examples of other inorganic particles include silica, alumina, titania, zirconia, manganese dioxide, dimanganese trioxide, and iron oxide. Among these, silica is preferable.
The ceria can be obtained, for example, by heat-treating a tetravalent cerium compound at about 600 to 800 ° C. in an oxidizing atmosphere. Examples of the tetravalent cerium compound that is a raw material for ceria include cerium hydroxide, cerium carbonate, and cerium oxalate.
The specific surface area of the ceria is preferably 5 to 100 m ² / g, more preferably 10 to 70 m ² / g, more preferably 10 to 30 m ² / g. By using ceria having a specific surface area in this range, an abrasive having excellent flatness can be obtained.
Examples of the silica include fumed silica and colloidal silica. The fumed silica can be obtained, for example, by reacting silicon chloride in the presence of hydrogen and oxygen. Colloidal silica can be obtained, for example, by a method of ion exchange of a silicate compound, a method of hydrolyzing an alkoxysilicon compound, and undergoing a condensation reaction.

When the inorganic particles are a mixture of ceria and other inorganic particles, the proportion of ceria in the total inorganic particles is preferably 60% by weight or more, and more preferably 90% by weight or more.
The inorganic particles are preferably inorganic particles composed only of ceria, or inorganic particles composed of ceria and silica, and more preferably inorganic particles composed of ceria alone.
The average particle diameter of the inorganic particles is preferably 0.01 to 1 μm, more preferably 0.02 to 0.7 μm, and still more preferably 0.04 to 0.3 μm. This average particle diameter can be measured by dynamic light scattering, laser scattering diffraction, transmission electron microscope observation, and the like. Of these, measurement by the laser scattering diffraction method is preferable because it is simple.
The pore volume of the inorganic particles is preferably 0.08 to 0.30 mL / g, more preferably 0.10 to 0.25 mL / g. The pore volume can be known by a gas adsorption method or the like.
By using inorganic particles having an average particle diameter and pore volume within the above ranges, an aqueous dispersion for chemical mechanical polishing excellent in the balance between the polishing rate and the dispersion stability in the aqueous dispersion can be obtained.

The (A) aqueous dispersion used in the method of the present invention is an aqueous dispersion containing inorganic particles as described above. (A) The content of the inorganic particles in the aqueous dispersion is preferably 1 to 40% by weight, more preferably 3 to 20% by weight, and further preferably 5 to 15% by weight. (A) Examples of the aqueous medium that can be used for the aqueous dispersion include water and a mixed solvent of water and a water-soluble alcohol. Examples of the water-soluble alcohol include methanol, ethanol, isopropanol, and the like. it can. Of these, water is preferably used.
(A) The liquidity of the aqueous dispersion is preferably 3.0 to 9.0, more preferably 3.5 to 8.0 in terms of pH value. The pH value can be adjusted with an acid or base described later as a component that can optionally be contained in the chemical mechanical polishing aqueous dispersion produced by the method of the present invention.

(B) Polyorganosiloxane As (B) polyorganosiloxane used for the manufacturing method of the chemical mechanical polishing aqueous dispersion of the present invention, for example, the following formula (I)

(In formula (I), R ¹ and R ² are each independently an alkyl group having 1 to 30 carbon atoms, an alkoxyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkyl group having 1 to 30 carbon atoms. An allyl group, and a part of hydrogen atoms of these groups is a carboxyl group, a hydroxyl group, a fluorine atom, an alkoxyl group having a fluorine atom, an amino group, an amide group, a sulfonic acid group, a C 2-30 poly (It may be substituted with an oxyalkylene chain.)
What has a repeating unit represented by these can be mentioned.
Specific examples of the alkyl group having 1 to 30 carbon atoms include, for example, a methyl group and an ethyl group;
Specific examples of the alkoxyl group having 1 to 30 carbon atoms include a methoxyl group and an ethoxyl group;
Specific examples of the aryl group having 6 to 30 carbon atoms include a phenyl group and a diphenyl group;
Specific examples of the polyoxyalkylene chain having 2 to 30 carbon atoms include polyoxyalkylene chains derived from polyalkylene glycols such as ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol.
The number of repeating units of the polyorganosiloxane is preferably 100 to 2,000, more preferably 200 to 1,500.

(B) The polyorganosiloxane is preferably used in the state of an aqueous dispersion containing the polyorganosiloxane. The content of (B) polyorganosiloxane in the aqueous dispersion is preferably 10 to 60% by weight, more preferably 20 to 50% by weight. The aqueous medium that can be used here is the same as that described above as the aqueous medium that can be used for the (A) aqueous dispersion.
(B) The aqueous dispersion containing polyorganosiloxane can further contain an emulsifier, silica, preservative and the like.
In the method for producing an aqueous dispersion for chemical mechanical polishing of the present invention, (B) the polyorganosiloxane is preferably used in the state of an emulsion containing an emulsifier. Examples of the emulsifier that can be used here include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Preferable examples include polyoxyethylene alkyl ether, polyoxyethylene propylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl phenyl ether, and polyether-modified silicone. The amount of the emulsifier used is preferably 40 parts by weight or less, more preferably 2 to 20 parts by weight with respect to 100 parts by weight of the polyorganosiloxane.

As said silica, it is the same as that mentioned above as silica which may be contained in the inorganic particle contained in (A) aqueous dispersion. However, silica is preferably, 100 to 500 m ² / g is measured specific surface area by the BET method is 50~700m ² / g used in an aqueous dispersion containing (B) a polyorganosiloxane It is more preferable. The particle size of silica is preferably 0.01 to 2.0 μm, more preferably 0.05 to 1.0 μm.
The amount of silica used is preferably 20 parts by weight or less, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the polyorganosiloxane.
The preservative is the same as described below as a preservative that can be optionally contained in the chemical mechanical polishing aqueous dispersion produced by the method of the present invention, but contains (B) polyorganosiloxane. The content of the preservative in the aqueous dispersion is preferably 10% by weight or less, and more preferably 1.0% by weight or less.

(B) In the case where the aqueous dispersion containing polyorganosiloxane further contains silica, at least a part, preferably all, of the silica is previously mixed with (B) polyorganosiloxane. It is preferable that Such mixing treatment can be performed by a known method using an appropriate mixing / dispersing apparatus. Examples of the mixing / dispersing device include a dissolver, a homomixer, a homodisper, a hibisdisper mix, a combination mix, a ball mill, a line mixer, a kneader, a colloid mill, a Henschel mixer, a Ladige mixer, and a high speeder. At this time, it may be heated if necessary, or an alkaline catalyst such as aqueous ammonia may be added. The conditions for the mixing treatment are preferably room temperature to 100 ° C., more preferably 50 to 80 ° C., preferably 10 minutes to 2 hours, more preferably 15 minutes to 1 hour.
Preferably, by adding an aqueous medium, polyorganosiloxane, silica and the above-mentioned emulsifier and the above-mentioned other additives as necessary to the above mixing / dispersing apparatus, a mixing treatment is performed, so that (B) polyorganosiloxane and silica are mixed. Can easily be obtained.

  When (B) the polyorganosiloxane is used as an aqueous dispersion containing it, preferably as an emulsion, the aqueous dispersion is diluted with deionized water, and (B) the polyorganosiloxane concentration is 10 ppm. The surface tension is preferably 15 to 55 (mN / m). This surface tension can be measured at 25 ° C. by a platinum ring method (Dunui method) using a digital tension meter manufactured by Kogai Co., Ltd. By using the aqueous dispersion having the above surface tension within this range, the scratch reduction effect of the chemical mechanical polishing aqueous dispersion produced by the method of the present invention can be further enhanced. (B) The surface tension of the aqueous dispersion containing polyorganosiloxane is preferably 15 to 55 mN / m, more preferably 20 to 40 mN / m.

(C) Cationic organic polymer particle The (C) cationic organic polymer particle refers to an organic polymer particle having a cationic residue in the particle. Here, examples of the cationic residue include residues represented by the following formulas (1) to (4).

Here, each R is independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. And more preferably a hydrogen atom or a methyl group. R ′ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms.
The cationic organic polymer particle (C) is not particularly limited as long as it has a cationic residue as described above. For example, the polymer particle having a cationic residue as described above, a cationic residue It can be a polymer particle or the like to which the surfactant having is attached.
(C) When the cationic organic polymer particle is a polymer particle having a cationic residue, the cationic residue can be located in at least one of the side chain and the terminal of the polymer.
The polymer having a cationic residue in the side chain can be obtained by homopolymerization of a cationic monomer, copolymerization of two or more cationic monomers, or copolymerization of a cationic monomer and other monomers.

Examples of the cationic monomer include an aminoalkyl group-containing (meth) acrylic acid ester, an aminoalkoxyalkyl group-containing (meth) acrylic acid ester, and an N-aminoalkyl group-containing (meth) acrylic acid ester. .
Examples of aminoalkyl group-containing (meth) acrylic acid esters include 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, and 3-dimethylaminopropyl (meta). ) Acrylate and the like;
Examples of aminoalkoxyalkyl group-containing (meth) acrylic acid esters include 2- (dimethylaminoethoxy) ethyl (meth) acrylate, 2- (diethylaminoethoxy) ethyl (meth) acrylate, 3- (dimethylaminoethoxy) propyl (meth) ) Acrylate and the like;
Examples of N-aminoalkyl group-containing (meth) acrylic acid esters include N- (2-dimethylaminoethyl) (meth) acrylamide, N- (2-diethylaminoethyl) (meth) acrylamide, and N- (2-dimethylamino). Propyl) (meth) acrylamide, N- (3-dimethylaminopropyl) (meth) acrylamide and the like can be mentioned.
Of these, 2-dimethylaminoethyl (meth) acrylate and N- (2-dimethylaminoethyl) (meth) acrylamide are preferred.
These cationic monomers may be in the form of salts added with methyl chloride, dimethyl sulfate, diethyl sulfate or the like. When the cationic monomer is a salt thereof, a salt added with methyl chloride is preferable.

Examples of other monomers include aromatic vinyl compounds, unsaturated nitrile compounds, (meth) acrylic acid esters (excluding those corresponding to the above cationic monomers), conjugated diene compounds, and vinyl esters of carboxylic acids. And vinylidene halide.
Examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, and halogenated styrene;
Examples of unsaturated nitrile compounds include acrylonitrile and the like;
Examples of (meth) acrylic acid esters (excluding those corresponding to the above cationic monomers) include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate, lauryl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and the like;
Examples of the conjugated diene compound include butadiene and isoprene;
Examples of vinyl esters of carboxylic acid include vinyl acetate and the like;
Examples of the vinylidene halide include vinyl chloride and vinylidene chloride.
Of these, styrene, α-methylstyrene, acrylonitrile, methyl methacrylate, butyl methacrylate, 2-hydroxyethyl acrylate and trimethylolpropane trimethacrylate are preferred.

Furthermore, if necessary, a monomer having two or more polymerizable unsaturated bonds may be copolymerized.
Examples of such monomers include divinylbenzene, divinylbiphenyl, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and propylene glycol diene. (Meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol Di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,2′-bis [4- (meth) acryloyloxypropoxyphenyl] propane, 2,2′-bis [4- (Meth) acryloyloxydiethoxydiphenyl] propane, glycerin tri (meth) acrylate, trimethylol bropan tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and the like can be given.
Of these, divinylbenzene or ethylene glycol dimethacrylate is preferred.

(C) When the cationic organic polymer particles are a copolymer of a cationic monomer and another monomer, the cationic monomer used as a raw material is 0.1 to 60 wt. %, Preferably 0.1 to 20% by weight.
The polymer as described above can be produced by a known method using a radical polymerization initiator. Examples of the radical polymerization initiator include benzoyl peroxide, potassium persulfate, ammonium persulfate, and 2,2′-azobisisobutyronitrile. The amount of the radical polymerization initiator used is preferably 0.05 to 3.0 parts by weight and more preferably 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the total amount of monomers.

The polymer having a cationic residue at the terminal is a polymerization initiator having a residue that remains at the terminal of the polymer and becomes a cationic residue when polymerizing the monomer as described above. (Hereinafter, sometimes referred to as “cationic polymerization initiator”). Moreover, you may copolymerize the monomer which has 2 or more of polymerizable unsaturated bonds as needed.
The monomer as a raw material in this case can be produced by homopolymerization or copolymerization of at least one monomer selected from the above-described cationic monomers and other monomers. Here, when a cationic monomer is used for part or all of the raw material monomer, a polymer having a cationic residue at both the side chain and the terminal of the polymer can be obtained.

Examples of the cationic polymerization initiator include 2,2′-azobis (2-methyl-N-phenylpropionamidine) dihydrochloride (sold as trade name “VA-545” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [N- (4-chlorophenyl) -2-methylpropionamidine) dihydrochloride (sold as trade name “VA-546” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [N- (4-hydroxyphenyl) -2-methylpropionamidine] dihydrochloride (sold as trade name “VA-548” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [2-methyl-N- (phenylmethyl) -propionamidine] dihydrochloride (sold as trade name “VA-552” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [2-methyl-N- (2-propenyl) propionamidine] dihydrochloride (sold as trade name “VA-553” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis (2-methylpropionamidine) dihydrochloride (sold as trade name “V-50” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride (sold as trade name “VA-558” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (sold as trade name “VA-057” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [2-methyl- (5-methyl-2-imidazolin-2-yl) propane) dihydrochloride (sold as trade name “VA-041” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [2- (2-imidazolin-2-yl) propane) dihydrochloride (sold as trade name “VA-044” from Wako Pure Chemical Industries, Ltd.),

2,2′-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl) propane] dihydrochloride (trade name “VA-” from Wako Pure Chemical Industries, Ltd.) 054 ”),
2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride (sold as trade name “VA-058” from Wako Pure Chemical Industries, Ltd.),
2,2′-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride (trade name “VA-059” from Wako Pure Chemical Industries, Ltd.) Sales),
2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride (sold as trade name “VA-060” from Wako Pure Chemical Industries, Ltd.) ,
2,2′-azobis [2- (2-imidazolin-2-yl) propane] (sold as trade name “VA-061” from Wako Pure Chemical Industries, Ltd.).
Among these, 2,2′-azobis (2-methylpropionamidine) dihydrochloride (trade name “V-50”), 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine It is preferred to use hydrate (trade name “VA-057”) and 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (trade name “VA-044”). .
The amount of the cationic polymerization initiator used is preferably 0.1 to 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the total amount of monomers.

(C) When the cationic organic polymer particles are polymer particles to which a surfactant having a cationic residue is attached, the polymer preferably has a neutral or anionic residue. . Such a polymer comprises the above-mentioned “other monomer” or “other monomer” and “monomer having two or more polymerizable unsaturated bonds” as described above, a radical polymerization initiator (the above cationic polymerization). Can be produced by a known method using a non-initiator).
As the monomer having an anionic residue, for example, the above-mentioned vinyl ester of carboxylic acid can be used. Here, the usage amount of the monomer having an anionic residue is preferably 1 to 60% by weight, more preferably 1 to 30% by weight, based on the total monomers.
The amount of the radical polymerization initiator used in this case is preferably 0.05 to 3.0 parts by weight, more preferably 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the total amount of monomers. .

Examples of the surfactant having a cationic residue include alkylpyridinyl chloride, alkylamine acetate, alkylammonium chloride, alkyneamine, and the like, as well as Patent Document 9 (Japanese Patent Laid-Open No. 60-235631). And reactive cationic surfactants such as diallylammonium halides.
The amount of the surfactant having a cationic residue is preferably 1 to 30 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the polymer.
An appropriate method can be used to attach the surfactant having a cationic residue to the polymer. For example, a dispersion containing polymer particles is prepared, and a solution of the surfactant is added thereto. It can be carried out.

(C) The average particle size of the cationic organic polymer particles is preferably 1.0 μm or less, more preferably 0.02 to 0.6 μm, and particularly preferably 0.04 to 0.3 μm. Is preferred. Further, this average particle size is preferably about the same as the average particle size of (A) inorganic particles, and more preferably 60 to 200% of the average particle size of (A) inorganic particles, In particular, it is preferably 60 to 100%. The average particle diameter can be measured by dynamic light scattering, laser scattering diffraction, transmission electron microscope observation, and the like.
(C) The cationic organic polymer particles are preferably used in the state of an aqueous dispersion containing the cationic organic polymer particles. The content of the (C) cationic organic polymer particles in the aqueous dispersion is preferably 5 to 25% by weight, more preferably 10 to 20% by weight. The aqueous medium that can be used here is the same as that described above as the aqueous medium that can be used for the (A) aqueous dispersion.

(D) Anionic water-soluble compound Examples of the anionic functional group of the (D) anionic water-soluble compound include a carboxyl group and a sulfone group.
(D) The anionic water-soluble compound is preferably an anionic water-soluble polymer or an anionic surfactant.
Examples of the anionic water-soluble polymer containing a carboxyl group as an anionic functional group include (co) polymers of unsaturated carboxylic acids, polyglutamic acid, polymaleic acid and the like. Examples of the anionic water-soluble polymer containing a sulfone group as an anionic group include (co) polymers of unsaturated monomers having a sulfone group.
The unsaturated carboxylic acid (co) polymer is a homopolymer of unsaturated carboxylic acid or a copolymer of unsaturated carboxylic acid and other monomers. As unsaturated carboxylic acid, (meth) acrylic acid can be mentioned, for example. Examples of other monomers include (meth) acrylamide, (meth) acrylic acid ester, styrene, butadiene, and isoprene. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, benzyl (meth) acrylate, and the like.

The (co) polymer of an unsaturated monomer having a sulfone group is a homopolymer of an unsaturated monomer having a sulfone group or a copolymer of an unsaturated monomer having a sulfone group and another monomer. It is a polymer. Examples of the unsaturated monomer having a sulfone group include styrene sulfonic acid, naphthalene sulfonic acid, and isoprene sulfonic acid. As the other monomer, the same monomer as the other monomer exemplified as the raw material of the unsaturated carboxylic acid copolymer described above can be used.
Of these anionic water-soluble polymers, unsaturated carboxylic acid (co) polymers can be preferably used, and poly (meth) acrylic acid is particularly preferable.
In addition, as the water-soluble organic polymer having an anionic group, a polymer in which all or part of the anionic group contained therein is a salt may be used. In this case, examples of the counter cation include ammonium ion, alkylammonium ion, potassium ion and the like, and among these, ammonium ion or alkylammonium ion is preferable.

  The weight average molecular weight (Mw) in terms of polyethylene glycol, measured by gel permeation chromatography (GPC) of the anionic water-soluble polymer as water, is preferably 3,000 to 30,000, more preferably It is 4,000 to 25,000, more preferably 5,000 to 20,000. By using an anionic water-soluble polymer having a weight average molecular weight within this range, the effect of further reducing the occurrence of surface defects on the surface to be polished is effectively expressed.

Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl diphenyl ether disulfonate, alkyl sulfosuccinate, alkyl ether sulfate and the like. Examples of counter cations of these anionic surfactants include ammonium ions, alkylammonium ions, and potassium ions.
Among these, a salt of dodecylbenzenesulfonic acid or a salt of alkyldiphenyl ether disulfonic acid is preferable, and an ammonium salt thereof is more preferable.
The anionic water-soluble compound (D) used in the present invention is preferably an anionic water-soluble polymer.

(D) The anionic water-soluble compound is preferably added as a solution dissolved in an aqueous medium. (D) When the anionic water-soluble compound is an anionic water-soluble polymer, the concentration of this solution is preferably 5 to 40% by weight, more preferably 10 to 30% by weight. On the other hand, when the anionic water-soluble compound (D) is an anionic surfactant, the concentration of this solution is preferably 1 to 30% by weight, more preferably 5 to 20% by weight.
The aqueous medium that can be used here is the same as that described above as the aqueous medium that can be used for the (A) aqueous dispersion.

Method for Producing Chemical Mechanical Polishing Aqueous Dispersion A method for producing a chemical mechanical polishing aqueous dispersion according to the present invention includes the above (B) to (A) in an aqueous dispersion containing inorganic particles containing (A) ceria. D) The process of adding a component in this order is included. In a preferred embodiment of the present invention, the aqueous dispersion after mixing the above components (A) to (D) contains the components (A) to (D) and other components that are optionally added to chemical machinery. It is a concentrated solution contained in a large amount with respect to the optimum value for use in polishing.
Hereinafter, a method for producing a concentrated liquid of chemical mechanical polishing aqueous dispersion and a chemical mechanical polishing aqueous dispersion obtained by diluting the concentrated liquid will be sequentially described.

Process for producing concentrated liquid of chemical mechanical polishing aqueous dispersion As the concentrated liquid of chemical mechanical polishing aqueous dispersion, prepare an aqueous dispersion containing inorganic particles containing (A) ceria as described above, preferably under stirring. (B) polyorganosiloxane, (C) cationic organic polymer particles, and (D) an anionic water-soluble compound in this order, and other optional additives as necessary. Manufactured.
The proportion of each component used is (A) 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the inorganic particles contained in the aqueous dispersion. (C) the cationic organic polymer particles are 5 to 100 parts by weight, preferably 10 to 80 parts by weight, more preferably 15 to 60 parts by weight, and (D) the anionic water-soluble compound is 5 to 100 parts by weight. Parts by weight, preferably 10 to 80 parts by weight, more preferably 15 to 60 parts by weight.
When mixing each component, it is preferable to stir as fast as possible from (B) addition of polyorganosiloxane to (D) after addition of an anionic water-soluble compound. By performing high-speed stirring, the inorganic particles and the components (B), (C) and (D) become uniform, and an abrasive as described later can be obtained with good dispersibility. The stirring speed is not particularly limited as long as the inorganic particles and the abrasive composed of these and each component do not settle, but the peripheral speed of the outermost periphery of the stirring blade is preferably 1 m / sec or more. .
The abrasive contained in the concentrated liquid produced as described above is composed of (A) inorganic particles contained in the aqueous dispersion and (C) cationic organic polymer particles (D). It was found to be in a unique aggregated state assembled through an anionic water-soluble compound.

The concentrated liquid may further contain other components such as an acid, a base, and a preservative as necessary.
As the acid, either an organic acid or an inorganic acid can be used. Examples of organic acids include p-toluenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid, maleic acid, phthalic acid Etc. Examples of inorganic acids include nitric acid, hydrochloric acid, and sulfuric acid.
The base is not particularly limited, and either an organic base or an inorganic base can be used. Examples of the organic base include nitrogen-containing organic compounds such as ethylenediamine, ethanolamine, and tetramethylammonium hydroxide. Examples of the inorganic base include ammonia, potassium hydroxide, sodium hydroxide, lithium hydroxide and the like.
The acid or base is preferably blended in an amount necessary to adjust the pH of the concentrate to 4 to 10, preferably 5 to 9. It is preferable to adjust the pH of the concentrate to the above range because the stability of the concentrate becomes good.

Examples of the preservative include bromonitroalcohol compounds and isothiazolone compounds. Examples of the bromonitroalcohol compound include 2-bromo-2-nitro-1,3-propanediol, 2-bromo-2-nitro-1,3-butanediol, 2,2-dibromo-2-nitroethanol, 2 , 2-dibromo-3-nitrilopropionamide and the like. Examples of the isothiazolone compounds include 1,2-benzisothiazolone-3-one, 5-chloro-2-methyl-4-isothiazolone-3-one, 2-methyl-4-isothiazolone-3-one, and 5-chloro-2. -Phenethyl-3-isothiazolone, 4-bromo-2-n-dodecyl-3-isothiazolone, 4,5-dichloro-2-n-octyl-3-isothiazolone, 4-methyl-5-chloro-2- (4 ' -Chlorobenzyl) -3-isothiazolone, 4,5-dichloro-2- (4'-chlorobenzyl) -3-isothiazolone, 4,5-dichloro-2- (4'-chlorophenyl) -3-isothiazolone, 4, 5-dichloro-2- (2′-methoxy-3′-chlorophenyl) -3-isothiazolone, 4,5-dibromo-2- (4′-chlorobenzyl) -3- Sothiazolone, 4-methyl-5-chloro-2- (4′-hydroxyphenyl) -3-isothiazolone, 4,5-dichloro-2-n-hexyl-3-isothiazolone, 5-chloro-2- (3 ′, 4'-dichlorophenyl) -3-isothiazolone and the like. Of these, 2-bromo-2-nitro-1,3-propanediol, 1,2-benzisothiazolone-3-one, 5-chloro-2-methyl-4-isothiazolone-3-one or 2-methyl-4 -Isothiazolone-3-one is preferred.
The content of the preservative in the concentrate is preferably 0.2% by weight or less, more preferably 0.15% by weight or less.

Chemical Mechanical Polishing Aqueous Dispersion The concentrated liquid obtained as described above contains abrasives and other components in a large amount relative to the optimum value for use in chemical mechanical polishing. Therefore, it is preferable to dilute and use the mixed aqueous dispersion for chemical mechanical polishing. The aqueous medium that can be used for dilution is the same as that described above as the aqueous medium that can be used for the (A) aqueous dispersion.
The amount of each component contained in the diluted chemical mechanical polishing aqueous dispersion is preferably as follows. In addition, the following is the ratio with respect to the whole chemical mechanical polishing aqueous dispersion at the time of use (after dilution).
Abrasive: preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, still more preferably 0.2 to 3% by weight
Polyorganosiloxane: preferably 1 to 500 ppm, more preferably 3 to 500 ppm, still more preferably 10 to 200 ppm
The amount of other components optionally contained in the diluted chemical mechanical polishing aqueous dispersion is preferably as follows. The following are ratios with respect to the whole chemical mechanical polishing aqueous dispersion after dilution.
Emulsifier: preferably 250 ppm or less, more preferably 5-100 ppm
Silica: preferably 100 ppm or less, more preferably 2 to 40 ppm
Acid: preferably 2% by weight or less, more preferably 1% by weight or less Base: preferably 1% by weight or less, more preferably 0.5% by weight or less Preservative: preferably 1% by weight or less, more preferably 0.01% ~ 0.5 wt%

The chemical mechanical polishing aqueous dispersion of the present invention preferably has a surface tension of 15 to 55 mN / m during use (after dilution). The surface tension can be measured at 25 ° C. by a platinum ring method (Dunui's method) using a digital tension meter manufactured by Kogai Co., Ltd. This surface tension is preferably 18 to 50 mN / m, more preferably 20 to 45 mN / m.
By using a chemical mechanical polishing aqueous dispersion having a surface tension in such a range, scratches can be reduced more effectively while maintaining a high polishing rate.

Chemical Mechanical Polishing Method The chemical mechanical polishing method of the present invention polishes the object to be polished using the above chemical mechanical polishing aqueous dispersion. A preferable material constituting the surface to be polished of the object to be polished is an insulating film. Specifically, an insulating film polished in a fine element isolation process (STI process), an interlayer insulating film of a multilayer wiring board, and the like can be given.
As an object to be polished in the STI process, for example, an object to be polished as shown in a schematic sectional view in FIG. 1 has a silicon substrate 1 having a groove 2 to be an element isolation region, a silicon oxide layer 3 formed on a surface other than the groove portion, and a silicon nitride layer 4 further formed on the silicon oxide layer 3. This is an object to be polished in which an insulating film 5 is deposited on a silicon nitride layer 4. In the STI process, the polishing is ideally performed until the silicon nitride layer 4 is exposed in the STI process.
Examples of the material constituting the insulating film to be polished in the STI process and the insulating film of the multilayer wiring board include a thermal oxide film, a PETEOS film (Plasma Enhanced-TEOS film), and an HDP film (High Density Plasma Enhanced-TEOS). Film), a silicon oxide film obtained by a thermal CVD method, a boron phosphorus silicate film (BPSG film), an insulating film called FSG, and the like.
The thermal oxide film is formed by exposing high temperature silicon to an oxidizing atmosphere and chemically reacting silicon and oxygen or silicon and moisture.
The PETEOS film is formed by chemical vapor deposition using tetraethylorthosilicate (TEOS) as a raw material and using plasma as an acceleration condition.
The HDP film is formed by chemical vapor deposition using tetraethylorthosilicate (TEOS) as a raw material and using high-density plasma as a promotion condition.
The silicon oxide film obtained by the thermal CVD method is formed by an atmospheric pressure CVD method (AP-CVD method) or a low pressure CVD method (LP-CVD method).
The boron phosphorus silicate film (BPSG film) is formed by an atmospheric pressure CVD method (AP-CVD method) or a low pressure CVD method (LP-CVD method).
The insulating film called FSG is formed by chemical vapor deposition using high-density plasma as an acceleration condition.

The chemical mechanical polishing method of the present invention can be carried out under appropriate conditions using a commercially available chemical mechanical polishing apparatus. Here, as a commercially available chemical mechanical polishing apparatus, for example, “EPO-112”, “EPO-222” (manufactured by Ebara Manufacturing Co., Ltd.), “Mirra-Mesa” (manufactured by Applied Materials) and the like can be mentioned. .
In the chemical mechanical polishing method of the present invention, when an object to be polished as shown in FIG. 1 is an object to be polished, the end point of chemical mechanical polishing can be easily achieved by tracking the current value of the motor that rotates the surface plate of the chemical mechanical polishing apparatus. Can know.
That is, in the chemical mechanical polishing method of the present invention, the current value tends to gradually increase at first, except for an unstable time at the beginning of polishing (for example, about 2 to 5 seconds after the start of polishing). This increasing tendency seems to be due to the fact that the initial level difference of the surface to be polished is eliminated as the polishing of the object to be polished progresses, the contact area between the polishing pad and the surface to be polished increases, and this increases the friction. It is. Thereafter, as the polishing further proceeds, the current value starts to decrease. In the graph showing the change over time of the current value, the time when the inflection point was shown after the current value changed from the increasing tendency to the decreasing tendency coincided with the end point of the chemical mechanical polishing process, that is, when the silicon nitride layer 4 was exposed. I found out that At this point, after the current value has changed from an increasing trend to a decreasing trend, the following formula (1)
d ² A / dt ² = 0 (1)
(In the above formula, A is the current value of the motor that rotates the platen of the chemical mechanical polishing apparatus, and t is the time.)
This is the time when the double differential equation represented by
On the other hand, in a known chemical mechanical polishing aqueous dispersion using ceria abrasive grains, there is no clear correlation between the current value of the motor rotating the platen and the polishing end point.

Preparation of Ceria Water Dispersion Cerium carbonate was heated in air at 700 ° C. for 4 hours to obtain ceria. This ceria was mixed with ion-exchanged water and pulverized with a bead mill using zirconia beads. This was allowed to stand for 24 hours and classified by separating the upper 90% by weight, thereby obtaining an aqueous dispersion of ceria containing 35.8% by weight of ceria.
With respect to ceria in this aqueous dispersion, the average particle diameter measured by laser diffraction was 170 nm. The ceria obtained by drying the above-mentioned ceria aqueous dispersion had a pore volume measured by a gas adsorption method using helium of 0.18 mL / g, and a specific surface area measured by a BET method using nitrogen. Was 34 m ² / g.

Preparation Synthesis Example 1 of Cationic Organic Polymer Particles (Preparation of Organic Polymer Particles (a))
60 parts by weight of methyl methacrylate and 40 parts by weight of styrene as monomers, 2,2′-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator (trade name “V-50”, manufactured by Wako Pure Chemical Industries, Ltd.) 0.5 parts by weight, 1 part by weight of a nonionic surfactant “ADEKASORP ER-10” (manufactured by ADEKA) and 400 parts by weight of ion-exchanged water as a surfactant are mixed and stirred in a nitrogen gas atmosphere. The mixture was heated to 70 ° C. and polymerized at the same temperature for 5 hours to obtain an aqueous dispersion containing 19.7% by weight of the organic polymer particles (a). The polymerization reaction conversion rate was 98.3%.
The average particle diameter of the obtained organic polymer particles (a) measured by a laser light diffraction method was 128 nm, and the zeta potential of the organic polymer particles (a) was +20 mV.
Synthesis Examples 2-3 and Comparative Synthesis Example 1 (Preparation of organic polymer particles (b) to (d))
The same procedure as in Synthesis Example 1 was conducted, except that the types and amounts of the monomers, polymerization initiators and surfactants used were as shown in Table 1, and organic polymer particles (b) to (d) were respectively prepared. An aqueous dispersion containing was obtained. Table 1 shows the polymerization reaction conversion rate, the particle content of each aqueous dispersion, the average particle size of each organic polymer particle, and the zeta potential in each synthesis example.

The abbreviations in Table 1 represent the following.
A polymerization initiator;
V-50: trade name, manufactured by Wako Pure Chemical Industries, Ltd. 2,2′-azobis (2-methylpropiondiamine) dihydrochloride surfactant;
ER-10: Trade name “ADEKA rear soap ER-10”, manufactured by ADEKA Corporation. Nonionic reactive surfactant.
ER-30: Trade name “ADEKA rear soap ER-30”, manufactured by ADEKA Corporation. Nonionic reactive surfactant.
DBSA: ammonium dodecylbenzenesulfonate.
The numbers corresponding to each component in Table 1. Each is the amount (part by weight) of the component added during the polymerization reaction. “-” Indicates that the component corresponding to the column was not added.

Preparation Example of Concentrate Preparation Example 1 (Preparation of Concentrate (1))
An aqueous dispersion containing 6.7% by weight of ceria was prepared by adding the aqueous dispersion of ceria prepared above as (A) inorganic particles to ion-exchanged water previously placed in a container. (B-1): SN-DEFOAMER 381 (trade name, manufactured by San Nopco Co., Ltd., an emulsion containing polyorganosiloxane and silica. Surface tension at 10 ppm dilution) = 31 mN / m) was added in an amount corresponding to 0.6 parts by weight of polyorganosiloxane based on 100 parts by weight of ceria, and stirring was continued for 10 minutes. Next, (C) the aqueous dispersion containing the organic polymer particles (a) as the cationic organic polymer particles, the amount of the organic polymer particles (a) is equivalent to 10 parts by weight with respect to 100 parts by weight of ceria. In addition, stirring was continued for 30 minutes. Further, (D) an aqueous solution containing 10% by weight of an ammonium polyacrylate having an Mw of 10,000 as an anionic water-soluble polymer, an amount corresponding to 40 parts by weight of polyammonium acrylate with respect to 100 parts by weight of ceria And a further 30 minutes of stirring was performed to obtain a concentrated liquid (1) which is an aqueous dispersion containing 7.5% by weight of an abrasive.
A small amount of the concentrated liquid (1) was taken, applied to a collodion film, dried, then stained with osmium tetroxide, and a transmission electron microscope (TEM) photograph was taken. This photograph is shown in FIG. 2A is a TEM image, and FIG. 2B is a reference diagram for TEM image observation. Referring to FIG. 2, it is understood that this abrasive is formed by collecting ceria and organic polymer particles via ammonium polyacrylate. In FIG. 2 (a), ceria appears blackest (corresponding to the blacked-out portion in FIG. 2 (b)), and the organic polymer particles appear as semitransparent spheres (white edges in FIG. 2 (b)). The semi-transparent portion that looks like an amoeba surrounding the ceria and the organic polymer particles is ammonium polyacrylate (corresponding to the hatched portion in FIG. 2B). In addition, a small amount of fine ceria is present in the ammonium polyacrylate.

Preparation Examples 2 to 4 (Preparation of concentrated liquids (2) to (4))
In Preparation Example 1, Preparation Example 1 except that the ceria content in the initial aqueous dispersion and the types and amounts of polyorganosiloxane, cationic organic polymer particles and anionic water-soluble compound were as shown in Table 2. Concentrated liquids (2) to (4) were prepared in the same manner as above.

In Table 2, the abbreviations indicating (B) polyorganosiloxane are as follows.
(B-1): SN-DEFOAMER 381 (trade name, manufactured by San Nopco Co., Ltd., an aqueous dispersion of an emulsion containing polyorganosiloxane and silica. Surface tension at dilution of 10 ppm = 31 mN / m)
(B-2): SN-500E (trade name, manufactured by San Nopco Co., Ltd., an aqueous dispersion of an emulsion containing polyorganosiloxane and silica. Surface tension at dilution of 10 ppm = 37 mN / m)
(B-3): TSA730 (trade name, manufactured by GE Toshiba Silicone Co., Ltd., an aqueous dispersion of an emulsion containing polyorganosiloxane and silica. Surface tension at 10 ppm dilution = 34 mN / m)
The surface tension at the time of 10 ppm dilution in the above is a platinum ring using a digital tension meter manufactured by Kogaisha Co., Ltd. for each diluted solution in which each polyorganosiloxane is diluted with deionized water to a polyorganosiloxane concentration of 10 ppm. It is the surface tension measured at 25 ° C. by the method.
Further, the abbreviations in the (D) component column represent the following, respectively.
(D) an anionic water-soluble compound;
PAAA: ammonium polyacrylate, Mw = 6,000.
DBSA: ammonium dodecylbenzenesulfonate.
In addition, all the addition amount of (B) thru | or (D) component is a weight part with respect to 100 weight part of ceria.

Comparative Preparation Example 1 (Preparation of Comparative Concentrate (1))
Ion exchange water is put in a container, and Ceria sol CESL-40N (average particle size: 40 nm, ceria content: 20% by weight) manufactured by Daiichi Rare Element Chemical Co., Ltd. is added thereto, and ceria is 6.3% by weight. An aqueous dispersion containing was prepared. An aqueous solution containing 10% by weight of ammonium polyacrylate having an Mw of 10,000 was added in an amount corresponding to 40 parts by weight of ammonium polyacrylate with respect to 100 parts by weight of ceria, and stirred for 10 minutes. This was filtered through a polypropylene depth filter having a pore size of 5 μm to obtain an abrasive concentrate of a chemical mechanical polishing aqueous dispersion containing 5% by weight of ceria.
Comparative Preparation Example 2 (Preparation of Comparative Concentrate (2))
Cerium carbonate was heated in air at 800 ° C. for 4 hours to obtain ceria. This ceria was mixed with ion-exchanged water and pulverized with a bead mill using zirconia beads. This was allowed to stand for 24 hours, and then classified by separating the upper 90% by weight of the ceria to obtain an aqueous dispersion containing 31.6% by weight of ceria.
Except that this ceria aqueous dispersion was used in place of CESL-40N, an abrasive concentrate of a chemical mechanical polishing aqueous dispersion containing 5% by weight of ceria was obtained in the same manner as in Comparative Example 1.
Comparative Preparation Examples 3 to 6 (Preparation of Comparative Concentrates (3) to (6))
The same procedure as in Preparation Example 1 was carried out except that (B) polyorganosiloxane was not added in Preparation Example 1, and an aqueous dispersion containing ceria was obtained.
Comparative concentrated liquids (3) to (6) were prepared by adding the following polyorganosiloxanes to the aqueous dispersion prepared above.
Comparative concentrated liquid (3): SN-DEFOAMER 381, an amount corresponding to 0.002 parts by weight with respect to 100 parts by weight of ceria as the amount of polyorganosiloxane.
Comparative concentrate (4): SN-DEFOAMER 381, an amount corresponding to 20 parts by weight per 100 parts by weight of ceria as the amount of polyorganosiloxane.
Comparative concentrated liquid (5): SN-500E, an amount corresponding to 0.002 parts by weight with respect to 100 parts by weight of ceria as the amount of polyorganosiloxane.
Comparative concentrated liquid (6): SN-500E, an amount corresponding to 20 parts by weight with respect to 100 parts by weight of ceria as the amount of polyorganosiloxane.

Example 1
(1) Preparation of Chemical Mechanical Polishing Aqueous Dispersion Ion exchange of the chemical mechanical polishing aqueous dispersion prepared above with the abrasive concentrate (1) so that the abrasive content is 0.5% by weight. Diluted with water to prepare an aqueous dispersion for chemical mechanical polishing.
(2) Measurement of surface tension About the chemical mechanical polishing aqueous dispersion after dilution, the surface tension was measured at 25 ° C. by a platinum ring method using a digital tension meter manufactured by Rouai Co., Ltd., model “RTM01DC”. However, it was 32 mN / m.
(3) Chemical mechanical polishing test Using the above-prepared chemical mechanical polishing aqueous dispersion (diluted), a chemical mechanical polishing wafer with a thermal oxide film of 8 inches in diameter was polished under the following conditions: Polishing was performed.
Polishing equipment: Model “EPO-112” manufactured by Ebara Corporation
Polishing pad: Rodel Nitta Co., Ltd., “IC1000 / SUBA400”
Aqueous dispersion supply speed: 200 mL / min Plate rotation speed: 100 rpm
Polishing head rotation speed: 107 rpm
Polishing head pressing pressure: 350 hPa

<Polishing rate evaluation method>
For a wafer with a thermal oxide film having a diameter of 8 inches, which is an object to be polished, the film thickness before polishing is measured in advance with an optical interference film thickness meter “NanoSpec 6100” (manufactured by Nanometrics Japan Co., Ltd.), Polishing was performed for 1 minute under the chemical mechanical polishing test conditions. The film thickness of the object to be polished after polishing was measured using the same optical interference film thickness meter as before polishing, and the difference from the film thickness before polishing, that is, the film thickness decreased by chemical mechanical polishing was determined. The polishing rate was calculated from the reduced film thickness and polishing time. The evaluation results are shown in Table 3. When the polishing rate exceeds 400 nm / min, the polishing rate is very good. When the polishing rate is 200 to 400 nm / min, the polishing rate is good. When the polishing rate is less than 200 nm / min, the polishing rate can be determined as poor.
<Scratch evaluation method>
The polished surface after polishing was inspected for defects by a wafer defect inspection apparatus “KLC351” manufactured by KLA-Tencor Corporation. First, the number of “KLC351” counted as “defects” was measured for the entire range of the wafer polished surface under the conditions of a pixel size of 0.39 μm and a threshold value of 20 (threshold). Next, these “defects” are sequentially displayed on the display of the apparatus, and the number of scratches on the entire wafer surface is measured by classifying whether or not each “defect” is a scratch. / Wafer. Of those counted as defects by the wafer defect inspection apparatus, those that are not scratched include, for example, adhering dust, stains generated during wafer manufacture, and the like.

Examples 2-9, Comparative Examples 1-6
In “(1) Preparation of aqueous dispersion for chemical mechanical polishing” in Example 1, each of the concentrated liquids shown in Table 3 was used, and the ion exchange was performed so that the content of the abrasive became the value shown in Table 3. An aqueous dispersion for chemical mechanical polishing was prepared by diluting with water, and subjected to a chemical mechanical polishing test in the same manner as in Example 1. The results are shown in Table 3.
In Comparative Example 1, scratching was not evaluated because it was clear that the polishing rate was too low to be suitable for practical use.
Comparative Example 7
The aqueous dispersion containing 31.6% by weight of ceria prepared in Comparative Preparation Example 2 and the aqueous dispersion containing organic polymer particles (a) prepared in Synthesis Example 1 were mixed and diluted with ion-exchanged water. A chemical mechanical polishing aqueous dispersion containing 0.5% by weight of ceria and 0.1% by weight of organic polymer particles (a) was prepared.
Table 3 shows the results of a chemical mechanical polishing test carried out in the same manner as in Example 1 using this chemical mechanical polishing aqueous dispersion.
Comparative Example 8
A chemical mechanical polishing aqueous dispersion was prepared in the same manner as in Comparative Example 7 except that the content of the organic polymer particles (a) in the chemical mechanical polishing aqueous dispersion was 0.2% by weight. A chemical mechanical polishing test was performed. The results are shown in Table 3.

Example 10
The chemical mechanical polishing aqueous dispersion (diluted) prepared in Example 1 was used, and 864 CMP (a test wafer manufactured by Advanced Materials Technology Co., Ltd.) as a polishing target. Section corresponding to the schematic diagram shown in FIG. The chemical mechanical polishing test was conducted for 3 minutes under the same conditions as in Example 1 except that the structure was used. The time change of the motor current (Motor current) for rotating the surface plate during the polishing test is shown in FIG.
Looking at the change with time of the current value in FIG. 3, after increasing from the unstable state in the initial stage of polishing, it shows an increasing tendency, reaching a maximum value in about 90 seconds after starting polishing, and then starting to decrease. An inflection point is seen in seconds.
In order to confirm that this point is the polishing end point, polishing is performed under the same polishing conditions while using the same type of object as described above and tracking the current value of the motor that rotates the surface plate of the chemical mechanical polishing apparatus. Polishing was terminated when the current value changed from an increasing tendency to a decreasing tendency and an inflection point was detected. As a result of analyzing the polished surface with an optical interference film thickness meter “NanoSpec 6100” (manufactured by Nanometrics Japan Co., Ltd.), the surface of the silicon nitride layer in each pattern with a pattern density of 30 to 90% and a 100 um pitch Since the thickness of the silicon oxide layer was almost 0 angstrom, it was found that the point of inflection point coincided with the polishing end point.

Comparative Example 9
In Example 10, the chemical mechanical polishing test was performed in the same manner as in Example 10 except that the chemical mechanical polishing aqueous dispersion (diluted) prepared in Comparative Example 2 was used as the chemical mechanical polishing aqueous dispersion. It was. The torque current during the polishing test is shown in FIG.
From the polishing rate evaluated in Comparative Example 2, it is estimated that the end point is reached in a shorter time than in the case of Example 10, but the current value of Comparative Example 9 does not show any tendency even near the assumed end point. It was also found that the end point cannot be detected by tracking the current value.

Schematic cross-sectional view showing an example of an object to be polished by the chemical mechanical polishing method of the present invention. The electron micrograph of the abrasive | polishing material contained in the concentrate (1) prepared in Preparation Example 1. 2A is a TEM image, and FIG. 2B is a reference diagram for TEM image observation. The graph which shows the change of the electric current value in Example 10 and Comparative Example 9. FIG.

Claims (6)

  (A) In an aqueous dispersion containing 100 parts by weight of inorganic particles containing ceria, (B) 0.05-5 parts by weight of polyorganosiloxane, (C) 5-100 parts by weight of cationic organic polymer particles, and (D ) A method for producing an aqueous dispersion for chemical mechanical polishing, comprising the step of sequentially adding 5 to 100 parts by weight of an anionic water-soluble compound.   (B) Polyorganosiloxane is added in the state of the emulsion containing this, The manufacturing method of the chemical mechanical polishing aqueous dispersion of Claim 1 characterized by the above-mentioned.   The method for producing an aqueous dispersion for chemical mechanical polishing according to claim 2, wherein the emulsion containing (B) polyorganosiloxane further contains silica.   A chemical mechanical polishing aqueous dispersion produced by the method according to any one of claims 1 to 3.   The chemical mechanical polishing aqueous dispersion according to claim 4, wherein the surface tension measured by a platinum ring method at 25 ° C is 15 to 55 mN / m.   A chemical mechanical polishing method comprising polishing an insulating film using the chemical mechanical polishing aqueous dispersion according to claim 4.