JP2008147688A - Aqueous dispersion element for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous dispersion element for chemical mechanical polishing which suppresses generation of polishing scratches without decelerating polishing speed, and to provide a method for removing extra insulation film in a minute element separation process. <P>SOLUTION: The aqueous dispersion element for chemical mechanical polishing contains 1.5 mass% or less of abrasive grains including ceria and mean dispersion grain diameter of the abrasive grains is 1.0 μm or more. The chemical mechanical polishing method polishes insulation films using the aqueous dispersion element for chemical mechanical polishing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  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 despite the multilayer wiring, etc., the chip size is increased, the number of processes accompanying the miniaturization is increased, and the cost of the chip is increased. . Under such circumstances, chemical mechanical polishing technology has been introduced for polishing processed films and the like, and has attracted attention. 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 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 layers and the definition of semiconductor devices have increased, further improvement in yield and throughput of semiconductor devices has been demanded. 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, for example, Patent Documents 3 to 5). However, although these techniques are effective in reducing polishing flaws, the polishing rate is reduced, and an improvement in throughput has not yet been achieved.
JP-A-5-326469 JP-A-9-270402 JP 2000-109809 A JP 2001-7061 A JP 2001-185514 A

  In view of the situation of the above-mentioned STI technology, the present invention provides a chemical mechanical polishing aqueous dispersion in which the generation of polishing flaws is suppressed without reducing the polishing rate, and a fine element isolation step using the aqueous dispersion. It is an object of the present invention to provide a chemical mechanical polishing method for removing an excess insulating film.

  The object of the present invention is, firstly, an aqueous dispersion containing ceria-containing abrasive grains at a concentration of 1.5% by mass or less, wherein the average dispersed particle diameter of the abrasive grains is 1.0 μm or more. Achieved by an aqueous dispersion for chemical mechanical polishing, characterized in that it is.

  Secondly, the above object of the present invention is achieved by a chemical mechanical polishing method in which the insulating film is removed using the chemical mechanical aqueous dispersion.

  According to the present invention, using the aqueous dispersion for chemical mechanical polishing in which the generation of polishing flaws is suppressed without reducing the polishing rate in the step of removing the insulating film in the manufacturing process of the semiconductor device, and the aqueous dispersion A chemical mechanical polishing method for removing an excess insulating film in a miniaturization element separation step is provided. According to the method of the present invention, the removal of the excess insulating film in the miniaturization element separation step can reduce surface defects on the surface to be polished and perform efficient chemical mechanical polishing.

  Hereinafter, each component of the chemical mechanical polishing aqueous dispersion of the present invention will be described in detail.

  The abrasive compounded in the chemical mechanical polishing aqueous dispersion of the present invention contains ceria and has an average dispersed particle diameter of 1.0 μm or more.

  The abrasive grains containing ceria and having an average dispersed particle diameter of 1.0 μm or more may be anything as long as this requirement is satisfied. For example, the abrasive grains are composite particles composed of ceria and cationic organic particles. Can be.

  The ceria can be obtained, for example, by heat-treating a tetravalent cerium compound 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 average particle diameter of ceria is preferably 0.01 to 3 μm, more preferably 0.02 to 1 μm, and still more preferably 0.04 to 0.7 μm. By using ceria having an average particle diameter in this range, it is possible to obtain an abrasive having an excellent balance between the polishing rate and the dispersion stability in the aqueous dispersion. The 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 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, abrasive grains having excellent flatness can be obtained.

  The cationic organic particles are organic particles having a cationic residue in the particles. 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 particles are not particularly limited as long as they have the cationic residues as described above. For example, polymer particles having the cationic residues as described above, surfactants having a cationic residue. Polymer particles to which is attached.

  When the cationic organic particles are polymer particle particles having a cationic residue, the cationic residue can be located in the side chain and / or 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 aminoalkyl group-containing (meth) acrylic acid esters,
Examples include aminoalkoxyalkyl group-containing (meth) acrylic acid esters and N-aminoalkyl group-containing (meth) acrylic acid esters.

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, halogenated styrene and the like;
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.

  Further, 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. Di (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-hexane Diol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,2'-bis [4- (meth) acryloyloxypropoxyphenyl] propane, 2,2'-bi S [4- (meth) acryloyloxydiethoxydiphenyl] propane, glycerin tri (meth) acrylate, trimethylolbropan tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and the like can be mentioned.

  Of these, divinylbenzene and ethylene glycol dimethacrylate are preferred.

  When the cationic organic particles are a copolymer of a cationic monomer and another monomer, the cationic monomer used as a raw material is preferably 1 to 60% by mass based on the total monomers, More preferably, it is 1-20 mass%.

  In addition, the said polymer can be manufactured by a well-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 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 the above-described cationic monomer and / or other monomer. Here, when a cationic monomer is used as 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 preferable to use hydrate (trade name “VA-057”) and 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (trade name “VA-044”). .

  When the cationic organic 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 includes 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 amount of the monomer having an anionic residue is preferably 1 to 60% by mass, and more preferably 1 to 30% by mass with respect to the total monomers.

  Examples of the surfactant having a cationic residue include alkylpyridinyl chloride, alkylamine acetate, alkylammonium chloride, alkyneamine and the like, as well as diallylammonium as described in JP-A-60-235631. And reactive cationic surfactants such as halides.

  The amount of the surfactant having a cationic residue is preferably 10 to 300 parts by mass, more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the polymer.

  To attach a surfactant having a cationic residue to the polymer, an appropriate method can be used. For example, by preparing a dispersion containing polymer particles and adding a surfactant solution thereto, Can be implemented.

  The average particle diameter of the polymer particles having cationic properties as described above is preferably 1.0 μm or less, more preferably 0.02 to 1.0 μm, and particularly preferably 0.04 to 0.00. It is preferable that it is 6 micrometers. The average particle system is preferably the same as that of the ceria average particle system, and more preferably 60 to 200% of the ceria average particle system. The average particle diameter can be measured by dynamic light scattering, laser scattering diffraction, transmission electron microscope observation, and the like.

  The abrasive grains contained in the chemical mechanical polishing aqueous dispersion of the present invention can be obtained by mixing the above-mentioned ceria and cationic polymer particles. When mixing ceria and cationic polymer particles, (1) prepare an aqueous dispersion containing ceria and an aqueous dispersion containing cationic polymer particles, respectively. A method of mixing, (2) a method of preparing an aqueous dispersion containing one of ceria and cationic polymer particles, and mixing the other by adding the other in solid form (powder); (3) Either of them may be mixed in a solid form (powder form) and then dispersed in an aqueous medium. Of these methods, the method (1) is preferred.

  In the case of the above method (1), as will be described later, an aqueous dispersion for chemical mechanical polishing in which an aqueous dispersion containing ceria and an aqueous dispersion containing cationic polymer particles are mixed in advance. May be prepared and used for the chemical mechanical polishing step, or an aqueous dispersion containing ceria and an aqueous dispersion containing cationic polymer particles are prepared respectively, and these are used for the chemical mechanical polishing apparatus. Abrasive grains may be formed by contact and mixing in a line or on a polishing pad.

  The ratio of the amount of the polymer particles having ceria and cationicity used is preferably 1 to 20 parts by mass, more preferably 1 to 10 parts by mass as the amount of polymer particles having cationicity per 100 parts by mass of ceria. is there.

  The abrasive grains obtained as described above contain ceria and have an average dispersed particle diameter of 1.0 μm or more. The average dispersed particle size is preferably 1.0 to 10 μm, more preferably 1.0 to 5.0 μm, and still more preferably 1 to 2.5 μm. The average particle diameter can be measured by dynamic light scattering, laser scattering diffraction, transmission electron microscope observation, and the like.

  The chemical mechanical polishing aqueous dispersion of the present invention contains the abrasive grains in a content of 1.5% by mass or less. This content is preferably 0.1 to 1.5% by mass, more preferably 0.5 to 1.0% by mass.

  The chemical mechanical polishing aqueous dispersion of the present invention contains abrasive grains having the above-mentioned ceria and an average dispersed particle diameter of 1.0 μm or more, but optionally, an aqueous solution having an anionic group. Organic polymer, acid, base and the like can be blended.

  The water-soluble organic polymer having an anionic group can be blended in order to increase the dispersion stability of the abrasive grains and at the same time further reduce the occurrence of surface defects on the surface to be polished. Examples of the anionic group include a carboxyl group and a sulfone group.

  Examples of the water-soluble organic polymer containing a carboxyl group as an anionic group include (co) polymers of unsaturated carboxylic acids, polyglutamic acid, and the like. Examples of the water-soluble organic 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 an unsaturated carboxylic acid or a copolymer of an unsaturated carboxylic acid and another monomer. 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 the 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 water-soluble organic polymers having an anionic group, 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 a part of the anionic group contained therein is a salt may be used. Examples of counter cations in that case include ammonium ions, alkylammonium ions, and potassium ions.

  The water-soluble organic polymer having an anionic group blended in the chemical mechanical polishing aqueous dispersion of the present invention, the weight average molecular weight in terms of polyethylene glycol measured by gel permeation chromatography with the solvent as water is preferably It is 3,000 to 30,000, more preferably 4,000 to 20,000, still more preferably 5,000 to 11,000. By using a water-soluble organic polymer having an anionic group having a weight average molecular weight within this range, the effect of improving the dispersion stability of the abrasive grains and at the same time reducing the occurrence of surface defects on the polished surface is effective. Will be expressed.

  The amount of the water-soluble organic polymer having an anionic group blended in the chemical mechanical polishing aqueous dispersion of the present invention is preferably per 100 parts by mass of abrasive grains containing ceria and having an average particle diameter of 1.0 μm or more. It is 600 parts by mass or less, more preferably 60 to 600 parts by mass, still more preferably 60 to 500 parts by mass, and particularly preferably 60 to 450 parts by mass. By using the amount within this range, a chemical mechanical aqueous dispersion excellent in the balance between the dispersion stability of the abrasive grains and the polishing rate can be obtained.

  The acid can improve the stability of the chemical mechanical polishing aqueous dispersion of the present invention and can further improve the polishing rate. The acid is not particularly limited, and either an organic acid or an inorganic acid can be used.

  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 and phthalic acid Is mentioned. Examples of the inorganic acid include nitric acid, hydrochloric acid, and sulfuric acid. These organic acids and inorganic acids can be used singly or in combination of two or more, and an organic acid and an inorganic acid can be used in combination.

  The amount of the acid is preferably 2% by mass or less, more preferably 1% by mass or less, when the chemical mechanical polishing aqueous dispersion is 100% by mass.

  The base can be added to adjust pH and further improve the dispersibility of the abrasive grains and the polishing rate. 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 and ethanolamine. Examples of the inorganic base include ammonia, potassium hydroxide, sodium hydroxide, lithium hydroxide and the like. These organic bases and inorganic bases can be used singly or in combination of two or more, and an organic base and an inorganic base can be used in combination.

  The compounding amount of the base is preferably 1% by mass or less, more preferably 0.5% by mass or less, when the chemical mechanical polishing aqueous dispersion is 100% by mass.

  The chemical mechanical polishing aqueous dispersion of the present invention is prepared by dispersing and dissolving the above-described constituents in an appropriate medium. Examples of the medium used in the chemical mechanical polishing aqueous dispersion of the present invention include water, a mixed medium of water and alcohol, a mixed medium of water and other components, and the like. Examples of the alcohol include methanol and ethanol. As a medium used for the chemical mechanical polishing aqueous dispersion of the present invention, it is preferable to use water.

  The pH of the chemical mechanical polishing aqueous dispersion is preferably pH 4-12. If it is this range, it can be set as the chemical mechanical polishing aqueous dispersion which can obtain the to-be-polished surface where the grinding | polishing speed | rate is high and polishing scratches were reduced, and the stability of the aqueous dispersion itself is also excellent.

  The chemical mechanical polishing aqueous dispersion of the present invention may be prepared in a state where all of the above-described constituent components are blended in the respective recommended blending amounts, and such a blending ratio is maintained. It is good also as preparing in a concentrated state, diluting before use, and using for a chemical mechanical polishing process.

  In the case of preparing in a concentrated state, the blending amount of abrasive grains is preferably 20% by mass or less from the viewpoint of long-term stability of the aqueous dispersion.

Chemical mechanical polishing method The chemical mechanical polishing method of the present invention polishes an insulating film using the above chemical mechanical polishing aqueous dispersion. Specifically, the insulating film polishing in the fine element isolation step (STI step), the polishing of the interlayer insulating film of the multilayer wiring board, and the like can be mentioned.

  As a material constituting the insulating film to be polished in the STI process and the insulating film of the multilayer wiring board, for example, a thermal oxide film, a PETEOS film (Plasma Enhanced-TEOS film), an HDP film (High Density Plasma Enhanced-) TEOS film), a silicon oxide film obtained by a thermal CVD method, 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. .

  Next, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Preparation of Ceria Aqueous Dispersion After dissolving bastonesite in nitric acid, recrystallization was repeated three times as carbonate to obtain highly purified cerium carbonate. This was heated in air at 900 ° C. for 5 hours to obtain ceria. The ceria was pulverized by a bead mill using zirconia beads, and then classified by a water tank process.

  The ceria particles thus obtained were dispersed in ion-exchanged water in the presence of nitric acid, the pH was adjusted to 6, and ceria water containing 15% by mass of ceria having an average particle size (secondary particle size) of 0.24 μm. A dispersion was obtained.

Synthesis Synthesis Example 1 of Organic Particles [Cationic Polymer Particles (a)]
70 parts by mass of styrene, 20 parts by mass of methyl methacrylate and 10 parts by mass of methyl chloride adduct of N- (3-dimethylaminopropyl) acrylamide (manufactured by Kojin Co., Ltd., trade name “DMAPAAQ”) as a monomer, polymerization 1 part by weight of an azo polymerization initiator (trade name “V50”, manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator, and a 27% by weight aqueous solution of dodecyltrimethylammonium chloride as a surfactant (manufactured by Kao Corporation, trade name “ Cotamine 24P ”)) 5 parts by mass and 400 parts by mass of ion-exchanged water as a solvent were placed in a 2 liter flask, heated to 70 ° C. with stirring in a nitrogen gas atmosphere, and polymerized at 70 ° C. for 6 hours. I let you. As a result, an aqueous dispersion containing styrene-methyl methacrylate copolymer particles [polymer particles (a)] having an average particle size of 0.31 μm having a cationic residue was obtained. The polymerization yield was 95%. Further, with respect to the polymer particles, the zeta potential measured by a laser Doppler electrophoresis light scattering method zeta potential measuring instrument (manufactured by COULTER, model “DELSA440”) was +25 mV.

Comparative Synthesis Example 1 [Preparation of aqueous dispersion containing anionic polymer particles (b)]
50 parts by mass of styrene as a monomer, 20 parts by mass of acrylonitrile and 30 parts by mass of methyl methacrylate, 1 part by mass of ammonium peroxide as a polymerization initiator, and polyoxyethylene alkylphenyl ether (trade name “Emulgen” manufactured by Kao Corporation) as a surfactant 920 ") 2 parts by mass and 400 parts by mass of ion-exchanged water were placed in a flask having a capacity of 2 liters, heated to 70 ° C with stirring in a nitrogen gas atmosphere, and polymerized at 70 ° C for 6 hours. As a result, an aqueous dispersion containing styrene-methyl methacrylate copolymer particles [polymer particles (b)] having an anionic residue and an average particle diameter of 0.42 μm was obtained. The polymerization yield was 94%. Further, the zeta potential of this polymerized particle measured as in Synthesis Example 1 was −16 mV.

Synthesis Examples 2 to 4
The polymer particles (c), (d) and (e) were prepared in the same manner as in Synthesis Example 1 except that the types and amounts of the monomer, polymerization initiator and surfactant were as shown in Table 1. Got. The average particle system and zeta potential of these polymer particles are shown in Table 1.

Preparation of a solution containing a water-soluble organic polymer having an anionic group An aqueous solution containing 40% by mass of polyacrylic acid (weight average molecular weight in terms of polyethylene glycol measured by GPC using a solvent as water is 8,000). 28 mass% aqueous ammonia was added in an amount corresponding to 80% of the carboxyl groups of the polyacrylic acid being neutralized.

  However, in Table 1, the number corresponding to each component is the amount (part by mass) added to the component during the polymerization reaction. “-” Indicates that the component corresponding to the column was not added.

Further, DMAPAAQ, V-50, Cotamine 24P, Emulgen 920 and Aqualon RN20 are trade names, which respectively represent the following.
DMAPAAQ: methyl chloride adduct of N- (3-dimethylaminopropyl) acrylamide (manufactured by Kojin Co., Ltd.)
V-50: dihydrochloride of 2,2′-azobis (2-methylpropionamidine) (manufactured by Wako Pure Chemical Industries, Ltd.)
Coatamine 24P: 27% by weight aqueous solution of dodecyltrimethylammonium chloride (manufactured by Kao Corporation)
Emulgen 920: Polyoxyethylene alkyl phenyl ether (manufactured by Kao Corporation)
Aqualon RN20: Nonionic reactive surfactant (Daiichi Kogyo Seiyaku Co., Ltd.)

Example 1
(1) Preparation of Aqueous Dispersion for Chemical Mechanical Polishing The amount of ceria aqueous dispersion prepared in “Preparation of Ceria Water Dispersion” above is equivalent to 10 parts by mass in terms of ceria, synthesized in Synthesis Example 1 above. Prepared by converting the aqueous dispersion containing the polymer particles (a) into polymer particles in an amount corresponding to 2 parts by mass and “Preparation of a solution containing the above water-soluble organic polymer having an anionic group” The solution containing the water-soluble polymer was converted to a water-soluble polymer in an amount corresponding to 25% by mass to prepare a concentrated product of the chemical mechanical polishing aqueous dispersion.

  Further, the concentrated product is diluted with ultrapure water so that the content of ceria is 0.8% by mass (corresponding to 0.96% by mass as abrasive grains containing ceria). An aqueous dispersion for mechanical polishing was prepared. The average dispersed particle size of the abrasive grains contained in the chemical mechanical polishing aqueous dispersion prepared here was measured by a laser diffraction method and found to be 1.57 μm.

Chemical mechanical polishing Using the chemical mechanical polishing aqueous dispersion prepared above, chemical mechanical polishing was performed using a PETEOS film having a diameter of 8 inches as an object to be polished under the following conditions.
Polishing machine: Ebara Manufacturing Co., Ltd., model “EPO-112”
Polishing pad: Rodel Nitta Co., Ltd., “IC1000 / SUBA400”
Aqueous dispersion supply amount: 200 mL / min Platen rotation speed: 100 times / min Polishing head rotation speed: 107 times / min Polishing head pressing pressure: 450 g / cm ²
Polishing time: 3 minutes

Evaluation of polishing rate Using optical interference type film thickness meter “NanoSpec 6100” (manufactured by Nanometrics Japan Co., Ltd.), the film thickness before and after polishing of the object to be polished in the chemical mechanical polishing is measured, and the difference is polished. The polishing rate was calculated by dividing by time.

  The polishing rate is shown in Table 2.

  When this value exceeds 20 nm / min, the polishing rate is good, and when it is less than 20 nm / min, the polishing rate is poor.

Evaluation of the number of scratches The PETEOS film after polishing was subjected to defect inspection using “KLA2351” manufactured by KLA-Tencor Corporation. First, the entire range of the wafer surface was measured under the conditions of a pixel size of 0.39 μm and a threshold of 50, and the number counted as “defects” by “KLA2351” was measured. Next, 250 of these “defects” are randomly extracted and observed, and it is determined whether each is a scratch or adhering dust, and the percentage of scratches in these “defects” is calculated. The number of scratches per wafer was calculated. The results are shown in Table 2.

  When this value is 50 pieces / surface or less, the number of scratches is very good, when it is 50-100 pieces / surface, the number of scratches is good, and when it is 101 pieces / surface or more, the number of scratches is poor.

Examples 2-6 and Comparative Examples 1-4
A concentrated product was prepared in the same manner as in Example 1 except that the types and amounts of each component were as shown in Table 2, and a chemical mechanical polishing aqueous dispersion was prepared and evaluated. The results are shown in Table 2.

  In Comparative Example 5, the uniformity of the polished surface after polishing was extremely poor, and scratches were not evaluated.

  According to Table 2, in Examples 1 to 6, the polishing rate is sufficiently high at 20 nm / min or more. Moreover, there are few scratches and it is excellent. On the other hand, in Comparative Examples 1 and 4, the speed of polishing the silicon oxide film was insufficient, and there were many scratches, which was a problem. In Comparative Examples 2 and 3, the polishing rate is not a problem, but there are many scratches and it is difficult to put it to practical use. In Comparative Example 5, the polishing rate was sufficient, but the uniformity of the polished surface after polishing was extremely poor.

Claims (5)

  A water for chemical mechanical polishing containing an abrasive containing ceria at a concentration of 1.5% by mass or less, wherein the average dispersed particle size of the abrasive is 1.0 μm or more. System dispersion.   2. The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the abrasive grains are composite particles composed of ceria and cationic organic particles.   The chemical mechanical polishing aqueous dispersion according to claim 1 or 2, further comprising an anionic water-soluble organic polymer.   An aqueous dispersion containing ceria having an average dispersed particle diameter of less than 1.0 μm and an aqueous dispersion containing cationic organic particles having an average dispersed particle diameter of less than 1.0 μm are mixed. Item 3. A process for producing an aqueous dispersion for chemical mechanical polishing according to Item 2.   A chemical mechanical polishing method comprising polishing an insulating film using the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 3.