JP2015035514A - Polishing liquid for cmp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid for CMP which makes possible to reduce the occurrence of polishing flaw in a face to be polished, and to achieve a high polishing speed and superior dispersion stability.SOLUTION: A polishing liquid for CMP comprises: polishing grains composed of aggregations which polishing material particles and cationic organic polymer particles form into with the aid of an anionic water-soluble polymer compound; and water. The polishing material particles each have a core-shell structure including a core layer and a shell layer. The core layer contains an oxide of at least one element selected from Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th and alkali-earth metals. The shell layer contains a cerium oxide.

Description

  The present invention relates to a polishing liquid for CMP. In particular, the present invention relates to a polishing slurry for CMP that suppresses generation of polishing flaws on a surface to be polished, has a high polishing rate, and is excellent in dispersion stability.

  In recent years, the storage capacity of a memory device has been dramatically increased as the degree of integration of semiconductor devices has increased and multilayer wiring has been achieved. On the other hand, as the chip size increases and the number of manufacturing processes increases with higher integration, the cost of the chip is increased. Under such circumstances, research on a processing technique for manufacturing a high-density and fine chip is underway, and one of such processing techniques is a CMP (Chemical Mechanical Polishing) technique. Can be mentioned. The CMP technique is a polishing technique for obtaining a smooth polished surface by a mechanical action by abrasive particles in a CMP polishing liquid and a chemical action by components contained in the CMP polishing liquid. For example, a semiconductor element manufacturing process Are used in the flattening step of the interlayer insulating film and the BPSG film (silicon dioxide film doped with boron, phosphorus or the like).

  Further, in the so-called STI technique, which is a so-called STI technique in the semiconductor manufacturing process, the CMP technique is used to polish and remove an excess portion of the silicon oxide insulating layer formed on the wafer substrate. It is done. Note that a stopper layer is formed below the silicon oxide insulating layer on the wafer substrate, and polishing can be stopped by utilizing a polishing rate difference between the silicon oxide insulating layer and the stopper layer. Therefore, in order to stop the polishing with high accuracy, it is preferable to use silicon nitride having a larger polishing rate ratio than the silicon oxide insulating layer as the material of the stopper layer.

In such a CMP technique, various abrasives are being studied in order to improve the flatness of the surface to be polished.
As the abrasive particles used in the CMP technique, silica particles are generally used, but the silica particles have a small difference between the polishing rate of the silicon oxide film and the polishing rate of the silicon nitride film, that is, the polishing selectivity is low. For this reason, in the STI technique, it is preferable to use cerium oxide particles having excellent polishing selectivity between a silicon oxide film and a silicon nitride film.

  For example, in the CMP process of the STI technology, a technique for obtaining a polished surface having a high polishing rate and relatively few polishing flaws by using an aqueous dispersion containing cerium oxide as abrasive particles as a polishing liquid for CMP is provided. (For example, see Patent Document 1 and Patent Document 2).

However, although cerium oxide particles have better polishing characteristics than conventional silica particles, when dispersed in a CMP polishing liquid, the cerium oxide particles tend to settle due to their large specific gravity, resulting in a decrease in polishing characteristics. On the other hand, when an additive such as a dispersant is excessively added to improve the polishing characteristics, the aggregation of the cerium oxide particles is promoted, the aggregation and precipitation become remarkable, and the dispersion stability is lowered.
In order to ensure dispersion stability against such problems, the first liquid that can suppress the agglomeration of abrasive grains made of abrasive particles and maintain the storage state, and the first liquid in an optimum state for polishing A method of storing separately for the second liquid to be adjusted is proposed (for example, see Patent Document 3). However, the amount of the first liquid and the second liquid that are not used up after being mixed can be stored only for a short period because the abrasive grains aggregate.

Japanese Patent No. 3335667 JP-A-9-270402 Japanese Patent No. 5177430

  An object of the present invention has been made in view of the above problems and circumstances, and provides a polishing slurry for CMP that suppresses generation of polishing flaws on a surface to be polished, has a high polishing rate, and is excellent in dispersion stability. That is.

As a result of examining the cause of the above-mentioned problems in order to solve the above-mentioned problems according to the present invention, abrasive grains and cationic organic polymer particles aggregated via an anionic water-soluble polymer compound, Water, the abrasive particles have a core-shell structure, the core layer contains an oxide of a specific element, and the shell layer contains cerium oxide, whereby the surface to be polished It has been found that a polishing slurry for CMP can be provided which suppresses the generation of polishing flaws, has a high polishing rate, and is excellent in dispersion stability.
That is, the said subject which concerns on this invention is solved by the following means.

1. Abrasive particles and cationic organic polymer particles aggregated via an anionic water-soluble polymer compound, and water,
The abrasive particles have a core-shell structure;
The core layer is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Containing an oxide of at least one element selected from Yb, Lu, W, Bi, Th and an alkaline earth metal, and
A polishing slurry for CMP, wherein the shell layer contains cerium oxide.

2. The abrasive particles further have an intermediate layer between the core layer and the shell layer; and
The intermediate layer is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm. 2. The polishing slurry for CMP according to item 1, comprising an oxide of at least one element selected from Yb, Lu, W, Bi, Th, and an alkaline earth metal, and cerium oxide.

  3. Item 1 or 2, wherein the first liquid containing the abrasive particles, the cationic organic polymer particles, and water is mixed with a second liquid containing the anionic water-soluble compound and water. The polishing liquid for CMP according to item 2.

ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the grinding | polishing damage | wound in a to-be-polished surface can be suppressed, the polishing liquid for CMP with high polishing rate and excellent dispersion stability can be provided.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
That is, the abrasive particles have a core-shell structure, and the core layer is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th and an oxide of at least one element selected from alkaline earth metals, and the shell layer, Since cerium oxide is contained, the specific gravity is lower than that of the cerium oxide particles while having the same polishing characteristics as the cerium oxide particles on the surface. Therefore, since the abrasive for polishing whose surface is coated with cerium oxide is contained in the polishing liquid for CMP, the generation of polishing flaws on the surface to be polished can be suppressed, and a high polishing rate can be obtained. Furthermore, since the specific gravity of the abrasive particles is low, the CMP polishing liquid of the present invention can maintain higher dispersibility over a longer period than the polishing liquid in which cerium oxide is dispersed.

The schematic diagram which shows the 3 layer structure of the abrasive particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 3 layer structure of the abrasive particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 3 layer structure of the abrasive particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 2 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 2 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention

The polishing slurry for CMP of the present invention comprises abrasive particles and cationic organic polymer particles aggregated via an anionic water-soluble polymer compound, and water, and the abrasive particles are: It has a core-shell structure, and the core layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co ), Nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd) ), Terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tongues Containing an oxide of at least one element selected from tantalum (W), bismuth (Bi), thorium (Th), and alkaline earth metal, and the shell layer containing cerium oxide . This feature is a technical feature common to claims 1 to 3.
Further, according to the present invention, the abrasive particles further include an intermediate layer between the core layer and the shell layer, and the intermediate layer includes Al, Sc, Ti, V, Cr, Mn, Fe , Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th and alkaline earth metals It is preferable to contain an oxide of at least one element and cerium oxide. Thereby, the preparation of the abrasive particles becomes easy, and the polishing liquid for CMP can be easily prepared.
In the present invention, it is preferable that a first liquid containing the abrasive particles, the cationic organic polymer particles, and water is mixed with a second liquid containing the anionic water-soluble compound and water. . Thus, even when the polishing liquid for CMP is prepared by mixing the first liquid and the second liquid and used, high dispersibility can be maintained over a long period of time after mixing.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

The polishing slurry for CMP of the present invention comprises abrasive grains in which abrasive particles and cationic organic polymer particles are aggregated via an anionic water-soluble polymer compound, and water.
The material, manufacturing method, application and the like of the polishing liquid for CMP of the present invention will be described below.

《Abrasive particles》
The abrasive particle is a constituent material of abrasive grains contained in the CMP polishing liquid of the present invention.

(Abrasive particle layer structure)
The abrasive particles according to the present invention have a core-shell structure, and the core layer 1 has Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Containing an oxide of at least one element selected from In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th, and an alkaline earth metal, and a shell Layer 3 contains cerium oxide.

  The abrasive particles preferably have an intermediate layer 2 between the core layer 1 and the shell layer 3, and preferably have a three-layer structure as shown in FIG. The intermediate layer 2 is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm. Yb, Lu, W, Bi, Th and an oxide of at least one element selected from alkaline earth metals and cerium oxide. As will be described later, the intermediate layer 2 may be formed integrally with the core layer 1 or the shell layer 3, and the abrasive particles may have a substantially two-layer structure.

  The specific configuration and material of the abrasive particles include, for example, a core layer 1 mainly composed of yttrium oxide, an intermediate layer 2 containing yttrium oxide and cerium oxide formed outside the core layer 1, and an intermediate layer. And a shell layer 3 mainly composed of cerium oxide formed on the outer side of 2. Here, in the present invention, the main component means that the content is 50 mol% or more.

  As such three-layer structure abrasive particles, for example, the core layer 1 of the abrasive particles shown in FIG. 2A contains almost no cerium oxide, and is mainly composed of yttrium oxide. Specifically, the cerium oxide content of the core layer 1 should just be below the cerium oxide content of the intermediate | middle layer 2 formed in the outer side of the core layer 1. FIG. The cerium oxide content of the intermediate layer 2 changes (decreases) in a constant concentration gradient from the outer side of the intermediate layer 2 (shell layer 3 side) to the inner side of the intermediate layer 2 (core layer 1 side). The cerium oxide content of the intermediate layer 2 may be not less than the cerium oxide content of the core layer 1 and not more than the cerium oxide content of the shell layer 3. The shell layer 3 formed on the outer side of the intermediate layer 2 contains cerium oxide at a ratio of approximately 100 mol%. Specifically, the cerium oxide content of the shell layer 3 is preferably 50 to 100 mol%, and particularly preferably 75 mol% or more. By making the content of cerium oxide contained in the shell layer 3 constituting the surface of the abrasive particles close to 100 mol%, the excellent polishing rate of cerium oxide can be exhibited.

  The abrasive particles having a three-layer structure may be configured as shown in FIG. 2B, for example. The abrasive particles are configured such that the ratio of yttrium oxide and cerium oxide contained in the intermediate layer 2 is constant regardless of the distance from the center of the abrasive particles and is approximately half of each.

Further, the abrasive particles may have a two-layer structure in which the core layer 1 and the intermediate layer 2 substantially form one layer, and the shell layer 3 is formed outside thereof.
As such abrasive particles having a two-layer structure, for example, a structure in which the core layer 1 and the intermediate layer 2 are not distinguished as shown in FIG. 2C may be used. Such abrasive particles are mainly composed of an intermediate layer 2 which has no boundary with the core layer 1 and contains approximately half of the contents of yttrium oxide and cerium oxide, and cerium oxide formed outside the intermediate layer 2. And a shell layer 3 as a component.

  The abrasive particles having a two-layer structure may be configured as shown in FIG. 2D, for example. In such abrasive particles, the intermediate layer 2 having no boundary with the core layer 1 is configured such that the cerium oxide content increases with a predetermined concentration gradient from the center side to the outside of the abrasive particles.

The material contained in the core layer 1 and the intermediate layer 2 of the abrasive particles has been described as an example of yttrium oxide that is not easily broken against stress applied during use, but is not limited to this. , Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W , Bi, Th, and an oxide of at least one element selected from alkaline earth metals.
Further, the oxide of the element contained in the core layer 1 of the abrasive particles is the same as the oxide of the element contained in the intermediate layer 2 (excluding cerium oxide), so that the bonding strength between the layers is maintained. This is preferable.

The abrasive particles have a three-layer structure having the intermediate layer 2, but may have a two-layer structure without the intermediate layer 2.
Further, the shell layer 3 of abrasive particles is mainly composed of cerium oxide, but may be formed only of cerium oxide.

(Method for producing abrasive particles)
An example of a manufacturing method in the case of manufacturing abrasive particles having a three-layer structure is shown as a method for manufacturing abrasive particles. Such a manufacturing method includes the following five steps.

(1) Core layer forming step The core layer forming step is performed first by Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd. A urea compound is added to an aqueous solution containing a salt of at least one element selected from Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th, and an alkaline earth metal, and the Al , Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W A first dispersion solution is prepared in which a basic carbonate of at least one element selected from Bi, Th, and alkaline earth metal is dispersed.

  Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu As the salt of at least one element selected from W, Bi, Th, and alkaline earth metal, for example, nitrates, hydrochlorides, sulfates, and the like can be used, and nitrates are preferably used.

Examples of urea compounds include urea, urea salts (eg, nitrates, hydrochlorides, etc.), N, N′-dimethylacetylurea, N, N′-dibenzoylurea, benzenesulfonylurea, p-toluenesulfonylurea, Trimethylurea, tetraethylurea, tetramethylurea, triphenylurea, tetraphenylurea, N-benzoylurea, methylisourea, ethylisourea and the like can be used, but urea is preferred.
In the following description, the core layer forming step is shown as an example in which a basic carbonate is formed using urea, but is not limited to this example.

  Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, The ion concentration of the element in an aqueous solution containing a salt of at least one element selected from W, Bi, Th, and alkaline earth metal is 0.001 mol / L to 0.1 mol / L, and urea is A concentration of 5 to 50 times the ion concentration is preferred. This is because the Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, A spherical shape that exhibits monodispersity by setting the ion concentration in an aqueous solution and the ion concentration of urea in an aqueous solution of at least one element selected from Yb, Lu, W, Bi, Th, and an alkaline earth metal within the range. This is because the abrasive particles can be synthesized.

Then, the first dispersion solution is heated and stirred at 80 ° C. or higher to grow a basic carbonate that becomes the core layer 1 dispersed in the first dispersion solution.
In the case of heating and stirring, if sufficient stirring efficiency is obtained, the shape of the stirrer is not specified, but in order to obtain higher stirring efficiency, a rotor / stator type stirrer should be used. Is preferred.

(2) Intermediate layer forming step In the intermediate layer forming step, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni are added to the first dispersion solution containing the basic carbonate formed in the core layer forming step. , Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th, and alkaline earth metal formation An aqueous solution containing the salt of the element contained in the process, for example, yttrium nitrate, and an aqueous solution containing the salt of Ce are added. Then, for example, by forming an intermediate layer 2 in which yttrium and cerium are mixed on the outside of the basic carbonate of yttrium that is the core layer 1, the core layer 1 is made to grow particles, and the basic carbonate having a larger particle diameter is formed. Get. Specifically, the addition rate of the aqueous solution added to the first dispersion solution is preferably 0.003 mmol / L to 3.0 mmol / L per minute, and in particular, the ratio of Ce in the addition amount is less than 90 mol%. It is preferable. This is because when the ratio of Ce in the addition rate and the addition amount is out of the range, it is difficult for the abrasive particles to be formed to be spherical particles exhibiting monodispersity. The first dispersion solution is preferably heated and stirred at 80 ° C. or higher while the aqueous solution is added at the above rate. This is because when heated and stirred at 80 ° C. or lower, decomposition of urea added in the core layer forming step does not proceed and particle formation is inhibited. Here, a dispersion solution in which particles in which the intermediate layer 2 is formed outside the core layer 1 is dispersed is referred to as a second dispersion solution.

(3) Shell layer forming step In the shell layer forming step, an aqueous solution containing a salt of Ce is added to the second dispersion solution in which the particles in which the intermediate layer 2 is formed outside the core layer 1 in the intermediate layer forming step are dispersed. In addition, the shell layer 3 mainly composed of a basic carbonate of Ce is formed outside the intermediate layer 2 to further grow the particles. The aqueous solution containing the Ce salt is preferably added at a rate of 0.003 mmol / L to 3.0 mmol / L per minute with heating and stirring at 80 ° C. or higher. This is because if the addition rate is out of the range, it will be difficult for the abrasive particles to be formed into spherical particles exhibiting monodispersity. As for the heating temperature, as in the case of the intermediate layer forming step, when heated and stirred at 80 ° C. or lower, the decomposition of urea added in the core layer forming step does not proceed and particle formation is inhibited. Here, the dispersion solution in which the particles in which the shell layer 3 is formed outside the intermediate layer 2 is dispersed is referred to as a third dispersion solution.

(4) Solid-liquid separation step In the solid-liquid separation step, the solid in which the shell layer 3 is formed outside the intermediate layer 2 is recovered from the third dispersion obtained in the shell layer formation step by an operation of solid-liquid separation. Then, an abrasive precursor is obtained. In the solid-liquid separation step, the abrasive precursor obtained as necessary may be dried and then transferred to the firing step.

(5) Firing step In the firing step, the basic carbonate abrasive precursor obtained by solid-liquid separation is fired at 400 ° C or higher in air or in an oxidizing atmosphere. The baked abrasive precursor becomes an oxide, and becomes an abrasive particle whose outer side is covered with cerium oxide.

(Abrasive particle size, polishing speed, surface accuracy)
Abrasive particles vary in the required level of particle size depending on their use, but as the finished surface accuracy of the polished surface after polishing increases, it is necessary to make the abrasive particles contained in the abrasive used finer For example, the average particle size needs to be 2.0 μm or less for use in the manufacturing process of a semiconductor device. The smaller the particle size of the abrasive, the higher the finished surface accuracy of the polished surface after polishing, whereas the smaller the particle size, the slower the polishing rate. For this reason, when the particle diameter is less than 0.02 μm, the advantage that the polishing rate of the cerium-based abrasive is faster than that of the abrasive such as colloidal silica is lost. Accordingly, the average particle diameter of the abrasive particles is preferably in the range of 0.02 to 2.0 μm, and more preferably in the range of 0.05 to 1.5 μm.
Further, in order to increase the planar accuracy after the polishing process, it is desirable to use an abrasive having a uniform particle diameter as much as possible and having a small particle diameter distribution variation coefficient.

<< Cationic organic polymer particles >>
The cationic organic polymer particles are a constituent material of abrasive grains contained in the CMP polishing liquid of the present invention.
In the present invention, the cationic organic polymer particle is a particle made of a compound that can become a cation under conditions such as the presence of an acid (hereinafter simply referred to as “can become a cation”). Specific examples include compounds having groups represented by the following formulas (1) to (4).

  In the above formulas (1) to (4), each R independently represents 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 carbon. It is a C1-C4 alkyl group, More preferably, it is a hydrogen atom or a methyl group. R ′ represents 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 is not particularly limited as long as it can be a cation, but for example, a group that can be a cation such as the substituents represented by the above formulas (1) to (4). Or polymer particles to which a surfactant having a group capable of becoming a cation is attached.

When the cationic organic polymer particles are polymer particles having a group capable of becoming a cation, the group capable of becoming a cation is located in at least one of a side chain and a terminal of the polymer.
A polymer having a group that can become a cation in the side chain is a homopolymerization of a monomer that can become a cation, a copolymerization of monomers that can become two or more cations, or a copolymerization of a monomer that can become a cation and other monomers. Can be obtained by:

Examples of the monomer that can be a cation include (meth) acrylic acid ester having an aminoalkyl group, (meth) acrylic acid ester having an aminoalkoxyalkyl group, (meth) acrylic acid amide, or an N-alkyl-substituted product thereof. N-aminoalkyl group containing (meth) acrylic acid ester etc. can be mentioned.
Examples of the (meth) acrylic acid ester having an aminoalkyl group include 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, and 3-dimethylaminopropyl. (Meth) acrylate etc .;
Examples of the (meth) acrylic acid ester having an aminoalkoxyalkyl group include 2- (dimethylaminoethoxy) ethyl (meth) acrylate, 2- (diethylaminoethoxy) ethyl (meth) acrylate, and 3- (dimethylaminoethoxy) propyl. (Meth) acrylate etc .;
Examples of (meth) acrylic acid amide or N-alkyl-substituted product thereof include (meth) acrylamide, methyl (meth) acrylamide 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-dimethyl). Aminopropyl) (meth) acrylamide, N- (3-dimethylaminopropyl) (meth) acrylamide, etc. can be mentioned, respectively.

Of these, 2-dimethylaminoethyl (meth) acrylate and N- (2-dimethylaminoethyl) (meth) acrylamide are preferred.
The monomer capable of becoming a cation may be in the form of a salt added with methyl chloride, dimethyl sulfate, diethyl sulfate or the like. When the monomer capable of becoming a cation is any of these salts, a salt added with methyl chloride is preferable.

Examples of the other monomers include aromatic vinyl compounds, unsaturated nitrile compounds, (meth) acrylic acid esters (excluding those corresponding to the above-mentioned monomers that can be cations), conjugated diene compounds, and carboxylic acids. And vinyl esters and vinylidene halides.
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-mentioned monomers that can be cations) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 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 ' -Bis [4- (meth) acryloyloxydiethoxydiphenyl] propane, glycerin tri (meth) acrylate, trimethylol bropan 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 polymer particles are a copolymer of a monomer that can be a cation and another monomer, the monomer that can be a cation used as a raw material is 0.1 to 60 with respect to the total monomers. It is preferable that it is mass%, and it is still more preferable that it is 0.1-20 mass%.
The polymer as described above can be produced by a known method using a radical polymerization initiator. Here, 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 mass, more preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the total amount of monomers.

The polymer having a group capable of becoming a cation at the terminal is a polymerization initiator having a group that can remain at the terminal of the polymer and become a cation as a polymerization initiator (hereinafter, “ It may be referred to as “cationic polymerization initiator”). Moreover, you may copolymerize the monomer which has two or more polymerizable unsaturated bonds as needed.
The monomer used as a raw material in this case can be produced by homopolymerization or copolymerization of at least one monomer selected from the above-described monomers that can be cations and other monomers. Here, when a monomer that can be a cation is used for part or all of the raw material monomer, a polymer having a group that can become a cation on 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 “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.), and the like.

Among these, 2,2′-azobis (2-methylpropionamidine) dihydrochloride (trade name “V-50”), 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine ] Hydrate (trade name “VA-057”) and 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (trade name “VA-044”) are preferably used. .
The amount of the cationic polymerization initiator used is preferably 0.1 to 5.0 parts by weight, more preferably 0.2 to 3.0 parts by weight with respect to 100 parts by weight of the total amount of monomers. Furthermore, it is preferable that it is 0.5-2.0 mass parts.

When the cationic organic polymer particle is a polymer particle to which a surfactant having a group capable of becoming a cation is attached, the polymer preferably has a neutral or anionic group. 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 group, for example, the vinyl ester of carboxylic acid described above can be used. Here, the usage amount of the monomer having an anionic group is preferably 1 to 60% by mass, and more preferably 1 to 30% by mass with respect to all monomers.
The amount of radical polymerization initiator used in this case is preferably 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the total amount of monomers. .
Examples of the surfactant having a group capable of becoming a cation include alkylpyridinyl chloride, alkylamine acetate, alkylammonium chloride, alkyneamine, and diallyl as described in JP-A-60-235631. And reactive cationic surfactants such as ammonium halides.
The amount of the surfactant having a group that can become a cation is preferably 1 to 30 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the polymer.

  An appropriate method can be used to attach a surfactant having a group capable of becoming a cation to the polymer. For example, a dispersion containing polymer particles is prepared, and a surfactant solution is added thereto. Can be performed.

  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. The average particle diameter can be measured by dynamic light scattering, laser scattering diffraction, observation with a transmission electron microscope, or the like.

<Anionic water-soluble compound>
An anionic water-soluble compound is a constituent material of abrasive grains contained in the polishing slurry for CMP of the present invention.
As an anionic functional group which an anionic water-soluble compound has, a carboxyl group, a sulfone group, etc. can be mentioned, for example.
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.
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.

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 monomer (co) polymer 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 are preferred, and poly (meth) acrylic acid is particularly preferred.
As these anionic water-soluble polymers, those in which all or part of the anionic groups contained therein are salts 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. Examples of such an anionic water-soluble polymer include ammonium polyacrylate.

  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.
As the anionic water-soluble compound used in the present invention, an anionic water-soluble polymer is preferable.

《Abrasive grains》
The abrasive grains contained in the polishing slurry for CMP of the present invention comprise (A) abrasive particles, (B) cationic organic polymer particles, and (C) an anionic water-soluble compound.

  The cationic organic polymer particles are preferably 10 to 80 parts by mass and more preferably 15 to 60 parts by mass with respect to 100 parts by mass of the abrasive particles. The anionic water-soluble compound is preferably 10 to 50 parts by mass and more preferably 15 to 40 parts by mass with respect to 100 parts by mass of the abrasive particles.

  It has been found that the abrasive grains are in a unique aggregate state in which the abrasive particles and the cationic organic polymer particles are aggregated via an anionic water-soluble compound by observation with an electron microscope.

  The amount of abrasive grains contained in the CMP polishing liquid of the present invention is preferably 0.1 to 2.0 mass%, more preferably 0.2 to 0.8 mass%, based on the total amount of the aqueous dispersion. %.

The polishing slurry for CMP of the present invention contains the above abrasive grains as an essential component, but may optionally contain an acid, a base, a preservative, and the like.
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 An acid etc. are mentioned. Examples of inorganic acids include nitric acid, hydrochloric acid, and sulfuric acid. The amount of these acids is preferably 2% by mass or less, more preferably 1% by mass or less, based on the entire CMP polishing liquid.
As the base, 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 content of these bases is preferably 1% by mass or less, more preferably 0.5% by mass or less, based on the entire CMP polishing liquid.
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)- -Isothiazolone, 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 these preservatives is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, based on the entire CMP polishing liquid.

The polishing slurry for CMP of the present invention is an aqueous dispersion containing the above-mentioned abrasive grains as essential components and acids, bases, preservatives and the like as optional components.
Examples of the dispersion medium that can be used in the polishing slurry for CMP of the present invention include water or a mixed solvent of water and a water-soluble alcohol. As water-soluble alcohol, methanol, ethanol, isopropanol etc. can be mentioned, for example. Among these, it is preferable to use water as a dispersion medium during production of the abrasive.

  The pH of the polishing slurry for CMP of the present invention is preferably 4.0 to 9.0, more preferably 5.0 to 8.5, and further preferably 5.5 to 8.0, in terms of 25 ° C. It is preferable that

  The polishing slurry for CMP of the present invention containing abrasive grains composed of the above components can be polished at a high speed with substantially no polishing scratches on the surface to be polished, and in particular, a fine element isolation step (STI step). ), And for polishing the interlayer insulating film of the multilayer wiring board.

<< Manufacturing method of polishing liquid for CMP >>
The polishing liquid for CMP of the present invention includes 0.1 to 10% by weight of abrasive particles and 5 to 100 parts by weight of cationic organic polymer particles with respect to 100 parts by weight of abrasive particles. It can manufacture by the method of including the process of adding the 2nd liquid containing 5-30 mass% of anionic water-soluble compounds.

  The first liquid is an aqueous dispersion, and the dispersion medium is the same as the dispersion medium for the desired CMP polishing liquid, and it is preferable to use water. The content of abrasive particles in the first liquid is preferably 0.25 to 7.5% by mass. The content of the cationic organic polymer particles in the first liquid can be determined according to the ratio of the abrasive particles to the cationic organic polymer particles in the abrasive grains contained in the desired CMP polishing liquid. The amount is preferably 10 to 80 parts by mass and more preferably 15 to 60 parts by mass with respect to 100 parts by mass of the abrasive particles contained in the first liquid. The pH of the first liquid is preferably 3.5 to 9.0, more preferably 4.0 to 8.0, and still more preferably 4.5 to 6.0. The first liquid can contain the above-described acid or base in order to bring the pH into the above-mentioned preferable pH range.

  To prepare the first liquid, (1) a method of preparing an aqueous dispersion containing abrasive particles and an aqueous dispersion containing cationic organic polymer particles, respectively, and mixing both, (2) polishing A method of preparing an aqueous dispersion containing one of material particles and cationic organic polymer particles, and adding the other in solid form (powder form), and (3) mixing both in solid form ( Any method of mixing in powder form and then dispersing it in an aqueous medium may be used. Of these methods, the method (1) is preferred.

  The second liquid is a solution, and the solvent is the same as the dispersion medium for the desired CMP polishing liquid, and it is preferable to use water. The amount of the anionic water-soluble compound contained in the second liquid is preferably 10 to 25% by mass, more preferably 15 to 20% by mass. The pH of the second liquid is preferably 4.0 to 9.0, more preferably 5.0 to 8.0, and still more preferably 5.5 to 7.0. The second liquid can contain the above-described acid or base in order to bring the pH into the above-mentioned preferable pH range.

By making the content of each component contained in the first liquid and the second liquid within the above preferable range, the polishing for CMP of the present invention containing abrasive grains of a uniform composition in an appropriate content using these components A liquid or a concentrate thereof can be easily obtained.
Prepare the first liquid and the second liquid prepared as described above, add the second liquid to this while preferably stirring the first liquid, add optional additional components as necessary, and further Accordingly, the polishing slurry for CMP of the present invention can be produced by diluting to adjust the content of abrasive grains.
In order to adjust the pH of the polishing liquid for CMP after mixing the first liquid and the second liquid, an acid or a base may be further added.
Further, when the CMP polishing liquid of the present invention contains the above-mentioned preservative, the preservative may be previously contained in one or both of the first liquid and the second liquid, or You may add a preservative further, after mixing the 1st liquid and 2nd liquid which do not contain a preservative. Among these, it is preferable to mix with the first liquid in advance.

  The aqueous dispersion thus prepared may be subjected to a CMP process after being filtered through a filter having a pore diameter of about 2 to 10 μm.

According to the polishing slurry for CMP of the present invention, the abrasive particles constituting the abrasive grains are configured as described above, so that they are high over a long period of time even after mixing the first liquid and the second liquid. In order to maintain dispersion stability, it can be produced and stored in advance as an aqueous dispersion containing all of the above components or a concentrate thereof.
Therefore, the polishing slurry for CMP of the present invention may be produced and stored as an aqueous dispersion containing all of the above components or a concentrate thereof, and the first and second liquids may be used as described above. They may be manufactured and stored separately and mixed and used as described above immediately before the chemical mechanical polishing step.

When the first liquid and the second liquid are produced and stored separately, the first liquid and / or the second liquid are prepared in a concentrated state while maintaining the content ratio of each component contained in each liquid. It may be. Accordingly, the first liquid contains 100 parts by mass of abrasive particles and 5 to 100 parts by mass of cationic organic polymer particles, and the second liquid contains an anionic water-soluble compound.
When the first liquid is a concentrate, the contents of the abrasive particles and the cationic organic polymer particles in the first liquid are each preferably 30% by mass or less, and each 20% by mass or less. Is more preferable. By setting the content of the abrasive particles and the cationic organic polymer particles in the concentrate that is the first liquid, precipitation of particles does not occur in the first liquid even after the first liquid is stored for a long period of time. Alternatively, even if sedimentation occurs, it can be easily redispersed. Therefore, by diluting it, it can be easily used for producing the CMP polishing liquid of the present invention. Therefore, the content of the abrasive particles in the first liquid is preferably 1 to 30% by mass, more preferably 2.5 to 20% by mass.
On the other hand, when the second liquid is a concentrate, the content of the anionic water-soluble compound in the second liquid is preferably 40% by mass or less. By adjusting the content of the anionic water-soluble compound in the concentrate as the second liquid, the second liquid can be made into a uniform and stable solution, and this can be maintained even after the second liquid has been stored for a long period of time. By diluting, it can be suitably used for the production of the polishing slurry for CMP of the present invention. Therefore, the content of the anionic water-soluble compound in the second liquid is preferably 5 to 40% by mass.

<< Chemical mechanical polishing using polishing liquid for CMP of the present invention >>
(Inorganic insulating film production method)
Examples of a method for producing an inorganic insulating film using the CMP polishing liquid of the present invention include a low pressure CVD method and a plasma CVD method.
Silicon oxide film formation by low-pressure CVD uses monosilane: SiH ₄ as the Si source and oxygen: O ₂ as the oxygen source. A silicon oxide film can be obtained by performing these SiH ₄ —O ₂ -based oxidation reactions at a low temperature of 400 ° C. or lower. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD. When doping phosphorus: P in order to achieve surface flattening by high-temperature reflow, it is preferable to use a SiH ₄ —O ₂ —PH ₃ -based reactive gas.
The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. There are two plasma generation methods, capacitive coupling type and inductive coupling type. The reaction as a gas, SiH ₄ as an Si source, an oxygen source as _{N 2} O was used was _SiH 4 -N ₂ O-based gas and _{TEOS-O 2} based gas using tetraethoxysilane (TEOS) in an Si source (TEOS- Plasma CVD method). The substrate temperature is preferably 250 to 400 ° C., and the reaction pressure is preferably 67 to 400 Pa. The silicon oxide film thus manufactured may be doped with an element such as phosphorus or boron.

Similarly, the silicon nitride film formation by the low pressure CVD method uses dichlorosilane: SiH ₂ Cl ₂ as the Si source and ammonia: NH ₃ as the nitrogen source. A silicon nitride film can be obtained by performing this SiH ₂ Cl ₂ —NH ₃ oxidation reaction at a high temperature of 900 ° C.
Examples of the reactive gas in forming a silicon nitride film by plasma CVD include SiH ₄ —NH ₃ based gas using SiH ₄ as a Si source and NH ₃ as a nitrogen source. The substrate temperature is preferably 300 to 400 ° C.

As a substrate, a semiconductor substrate, that is, a substrate having a silicon oxide film or a silicon nitride film formed on a semiconductor substrate, such as a semiconductor substrate in which a circuit element and a wiring pattern are formed, or a semiconductor substrate in a stage in which a circuit element is formed Can be used. By polishing the silicon oxide film or silicon nitride film formed on such a semiconductor substrate with the CMP polishing liquid, unevenness on the surface of the silicon oxide film can be eliminated and the entire surface of the semiconductor substrate can be made smooth. it can.
Moreover, the polishing slurry for CMP of the present invention can also be used for STI. In order to use for STI, the ratio of the silicon oxide film polishing rate to the silicon nitride film polishing rate and the silicon oxide film polishing rate / silicon nitride film polishing rate must be 10 or more. If this ratio is too small, the difference between the silicon oxide film polishing rate and the silicon nitride film polishing rate becomes small, and polishing cannot be stopped at a predetermined position when performing STI. Further, when this ratio is 50 or more, the polishing rate of the silicon nitride film is further reduced and the polishing can be easily stopped, which is more suitable for STI.

(Polishing equipment)
As a polishing apparatus, a general polishing apparatus having a surface plate with a holder for holding a semiconductor substrate and a polishing cloth (pad) attached (a motor or the like whose rotation speed can be changed) is attached. As an abrasive cloth, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used, and there is no restriction | limiting in particular. Further, it is preferable that the polishing cloth is subjected to groove processing so that the polishing liquid for CMP is accumulated. The polishing conditions are not limited, but the rotation speed of the surface plate is preferably low rotation of 200 rpm or less so that the semiconductor substrate does not jump out, and the pressure applied to the semiconductor substrate is 1 kg / cm ² or less so that no scratches are generated after polishing. Is preferred. While the semiconductor substrate is being polished, the CMP polishing liquid is continuously supplied to the polishing cloth by a pump or the like. Although there is no restriction | limiting in this supply amount, It is preferable that the surface of polishing cloth is always covered with the polishing liquid for CMP.

(Washing)
The semiconductor substrate after completion of polishing is preferably washed in running water and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. After forming the flattened shallow trench in this way, an aluminum wiring is formed on the silicon oxide insulating film layer, and after forming the silicon oxide insulating film again between the wirings and on the wiring by the above method, By polishing using a polishing liquid for CMP, irregularities on the surface of the insulating film are eliminated, and the entire surface of the semiconductor substrate is smoothed. By repeating this step a predetermined number of times, a semiconductor having a desired number of layers can be manufactured.

<Other applications>
The polishing slurry for CMP of the present invention includes not only a silicon oxide film formed on a semiconductor substrate, but also a silicon oxide film formed on a wiring board having a predetermined wiring, an inorganic insulating film such as glass and silicon nitride, a photomask Optical glass such as lenses and prisms, inorganic conductive films such as ITO, optical integrated circuits / optical switching elements / waveguides composed of glass and crystalline materials, optical single-crystals such as scintillators, solid-state lasers, etc. Crystals, sapphire substrates for blue laser LEDs, semiconductor single crystals such as SiC, GaP, and GaAS, glass substrates for magnetic disks, magnetic heads, and the like can be polished.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

[Example 1]
<< Preparation of abrasive particles 1-8 >>
(Preparation of abrasive particles 1)
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained in the above operation (1), a mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution 300 mL and 0.32 mol / L cerium nitric acid aqueous solution 300 mL was added at a rate of 10 mL / min. It added at 90 degreeC, heating and stirring.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 1.
(5) The obtained abrasive particles 1 were monodisperse particles having an average particle size of 0.40 μm and a particle size distribution coefficient of variation of 11% from a scanning electron micrograph (SEM image) of 100 particles. Here, the particle size distribution variation coefficient was determined by the following equation.
Coefficient of variation (%) = (standard deviation of particle size distribution / average particle size) × 100
(6) The abrasive particles were subjected to cross-section processing using a focused ion beam (FB-2000A) manufactured by Hitachi High-Technologies, and a surface passing through the vicinity of the particle center was cut out. From the cut surface, elemental analysis was performed using STEM-EDX (HD-2000) manufactured by Hitachi High-Technologies, and the particle composition distribution was evaluated. As a result, the abrasive particle 1 has a three-layer structure. In cross section, a core layer of yttrium of 0.3 μm, an intermediate layer (molar ratio of yttrium: cerium = 1: 4) with a layer thickness of 0.04 μm on the outer side, and a layer of 0.01 μm on the outer side (outermost surface) It was found that a shell layer of cerium oxide was formed with a thickness.

(Preparation of abrasive particles 2)
(1) 10 L of 0.05 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 1.0 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained in the above operation (1), a mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution 300 mL and 0.32 mol / L cerium nitric acid aqueous solution 300 mL was added at a rate of 10 mL / min. It added at 90 degreeC, heating and stirring.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated by a membrane filter and fired at 600 ° C. to obtain abrasive particles 2.
(5) As with the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 2 were evaluated. The abrasive particles 2 are monodisperse particles having an average particle diameter of 0.62 μm and a coefficient of variation of 14%, a core layer diameter of 0.57 μm (yttrium), and an intermediate layer thickness of 0.02 μm (yttrium: cerium = 1: 4) and a shell layer thickness of 0.005 μm (cerium oxide).

(Preparation of abrasive particles 3)
(1) 10 L of a 0.1 mol / L yttrium nitric acid aqueous solution was prepared, urea was added to this aqueous solution so that the concentration of urea was 2.0 mol / L, and after sufficient stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained in the above operation (1), a mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution 300 mL and 0.32 mol / L cerium nitric acid aqueous solution 300 mL was added at a rate of 10 mL / min. It added at 90 degreeC, heating and stirring.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 3.
(5) In the same manner as the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 3 were evaluated. The abrasive particles 3 are monodisperse particles having an average particle diameter of 0.75 μm and a coefficient of variation of 19%, a core layer diameter of 0.72 μm (yttrium), and an intermediate layer thickness of 0.01 μm (yttrium: cerium = 1: 4) and a shell layer thickness of 0.005 μm (cerium oxide).

(Preparation of abrasive particles 4)
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained by the operation of (1), 300 mL of 0.4 mol / L yttrium nitric acid aqueous solution is added at a rate of (10-0.16 t) mL / min and 0.4 mol / L cerium. 300 mL of an aqueous nitric acid solution was added at a rate of (0.16 t) mL / min while heating and stirring at 90 ° C. However, t represents time (minutes) from the start of addition, and the addition rate is changed as a function with time.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 4.
(5) In the same manner as the abrasive particles 1, the particle diameter and elemental analysis of the abrasive particles 4 were evaluated. The abrasive particles 4 are monodisperse particles having an average particle diameter of 0.37 μm and a coefficient of variation of 15%, a core layer diameter of 0.24 μm (yttrium), and an intermediate layer thickness of 0.06 μm (yttrium: cerium = 1: And a shell layer thickness of 0.005 μm (cerium oxide).

(Preparation of abrasive particles 5)
(1) Prepare 10 L of nitric acid aqueous solution containing 0.005 mol / L yttrium and 0.005 mol / L cerium, add urea so that the concentration is 0.20 mol / L, and stir well at 90 ° C. Stir for hours.
(2) To the dispersion obtained by the operation of (1) above, a mixture of 600 mL of a 0.08 mol / L yttrium nitric acid aqueous solution and 600 mL of a 0.32 mol / L cerium nitric acid aqueous solution is added at a rate of 10 mL / min. It added at 90 degreeC, heating and stirring.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 5.
(5) In the same manner as the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 5 were evaluated. The abrasive particles 5 were monodisperse particles having an average particle diameter of 0.38 μm and a coefficient of variation of 19%.
The abrasive particles 5 had a substantially two-layer structure in which a core layer of 0.31 μm mixed with yttrium and cerium and a shell layer of cerium oxide having a layer thickness of 0.035 μm were formed on the outer side. In the region 0.03 μm from the outside of the core layer, there was a region having a higher cerium ratio than the central portion of the core layer.

(Preparation of abrasive particles 6)
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained by the operation of (1), 600 mL of a 0.40 mol / L yttrium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(3) To the dispersion obtained in the above operation (2), 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in the above operation (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 6.
(5) As with the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 6 were evaluated. The abrasive particles 6 were monodispersed particles having an average particle diameter of 0.45 μm and a coefficient of variation of 15%. The abrasive particles 6 had a two-layer structure with a core layer diameter of 0.43 μm (yttrium) and a shell layer thickness of 0.01 μm (cerium oxide).

(Preparation of abrasive particles 7)
(1) 10 L of water was prepared, urea was added so that it might be 0.20 mol / L, and after stirring sufficiently, it was heated and stirred until it reached 90 ° C.
(2) To the dispersion obtained by the operation of (1) above, a mixture of 600 mL of a 0.08 mol / L yttrium nitric acid aqueous solution and 600 mL of a 0.32 mol / L cerium nitric acid aqueous solution is added at a rate of 10 mL / min. It added at 90 degreeC, heating and stirring.
(3) The abrasive precursor precipitated from the dispersion obtained in the above operation (2) was separated with a membrane filter and baked at 600 ° C. to obtain abrasive particles 7 as a comparative example.
(4) In the same manner as the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 7 were evaluated. The abrasive particles 7 were monodisperse particles having an average particle diameter of 0.40 μm and a coefficient of variation of 13%, and had a single-layer structure with a molar ratio of yttrium: cerium = 1: 4.

(Preparation of abrasive particles 8)
(1) Cerium carbonate was heated in air at 700 ° C. for 4 hours to obtain cerium oxide. This cerium oxide was mixed with ion-exchanged water and pulverized by a bead mill using zirconia beads. This was allowed to stand for 72 hours and classified by separating the upper portion corresponding to 90% by mass, and cerium oxide particles (abrasive particles 8) containing 28.7% by mass of cerium oxide particles (abrasive particles 8). ) Was obtained.
(2) When the cerium oxide particles (abrasive particles 8) obtained by drying the aqueous dispersion were evaluated for the particle size of the abrasive particles 8 in the same manner as the abrasive particles 1, the average particle size was 0. .14 μm.

<< Preparation of Cationic Organic Polymer Particles (a) to (c) >>
(Preparation of cationic organic polymer particles (a))
Methyl methacrylate 40 parts by mass, 2-dimethylaminoethyl (meth) acrylate 20 parts by mass and styrene 40 parts by mass, 2,2′-azobis (2-methylpropionamidine) dihydrochloride (trade name “V” as a polymerization initiator) -50 ", manufactured by Wako Pure Chemical Industries, Ltd.) 0.5 parts by mass, 1 part by mass of a nonionic surfactant" Adekaria Soap ER-10 "(manufactured by ADEKA) as a surfactant, and ion exchange Cationic organic polymer particles (a) were obtained by mixing 400 parts by mass of water, heating to 70 ° C. with stirring in a nitrogen gas atmosphere, and polymerizing at that temperature for 5 hours. The average particle size was 126 nm, and the particle content was 19.5% by mass.

(Preparation of cationic polymer particles (b) and (c))
In the preparation of the cationic polymer particles (a), the monomers used were changed to 23 parts by weight of methyl methacrylate, 12 parts by weight of 2-dimethylaminoethyl (meth) acrylate, 64 parts by weight of styrene and 1 part by weight of divinylbenzene. The cationic polymer particles (b) were changed in the same manner except that the surfactant used was changed to 0.5 parts by mass of the nonionic surfactant “ADEKA rear soap ER-30” (manufactured by ADEKA). ) Was prepared. The average particle size was 269 nm, and the particle content was 19.8% by mass.
Further, in the preparation of the cationic polymer particles (a), monomers used are 40 parts by mass of methyl methacrylate, 20 parts by mass of 2-dimethylaminoethyl (meth) acrylate, 33 parts by mass of styrene, 5 parts by mass of divinylbenzene, and In the same manner except that the surfactant used was changed to 2 parts by weight of methylmethacrylamide and the surfactant used was changed to 1 part by weight of the nonionic surfactant “ADEKA rear soap ER-30” (manufactured by ADEKA) Cationic polymer particles (c) were prepared. The average particle size was 59 nm and the particle content was 19.7% by mass.

<< Preparation of polishing liquids 1-32 for CMP >>
(Preparation of polishing liquid 1 for CMP)
(1) Preparation of first liquid Abrasive particles 1 were added to ion-exchanged water previously placed in a container, and diluted so that the content of abrasive particles was 6.25% by mass. The aqueous dispersion containing the cationic organic polymer particles (a) was added thereto in such an amount that the content of the cationic organic polymer particles (a) in the first liquid was 0.625% by mass. The mixture was further stirred for 30 minutes to prepare a first liquid that was an aqueous dispersion containing abrasive particles 1 and cationic organic polymer particles (a).

(2) Preparation of second liquid A second liquid, which is an aqueous solution containing 10% by mass of ammonium polyacrylate having a weight average molecular weight Mw of 10,000 as an anionic water-soluble compound, was prepared.

(3) Preparation of polishing liquid 1 for CMP While stirring the first liquid prepared above, the second liquid was added thereto, and the amount of the anionic water-soluble compound was 100 parts by mass of the abrasive particles 1 in the first liquid. Was added in an amount corresponding to 40 parts by mass, and stirring was further continued for 30 minutes. By filtering this through a polypropylene depth filter having a pore diameter of 5 μm, 100 parts by mass of abrasive particles 1 (5.0% by mass), 10 parts by mass of cationic organic polymer particles (a) (0.5% by mass) ) And an anionic water-soluble compound, a polishing slurry concentrate 1 for CMP containing 7.5% by mass of abrasive grains 1 composed of 40 parts by mass of ammonium polyacrylate (2.0% by mass) was obtained.
The CMP polishing liquid 1 was obtained by diluting the CMP polishing liquid concentrate 1 so that the content of the abrasive grains 1 was 2.00% by mass.

(Preparation of polishing liquids 2-16 for CMP)
In the preparation of the polishing liquid 1 for CMP, the types and contents of the abrasive particles and the cationic organic polymer particles in the first liquid and the anionic water-soluble compound in the second liquid were changed as shown in Table 1. In the same manner, polishing liquid concentrates 2 to 16 for CMP containing abrasive grains 2 to 16 were prepared. The compositions of the abrasive grains 2 to 16 were as shown in Table 2.
In Tables 1 to 4, PAAA (1) represents ammonium polyacrylate having a weight average molecular weight Mw of 10,000, and PAAA (2) represents ammonium polyacrylate having a weight average molecular weight Mw of 6,000. DBSA indicates ammonium dodecylbenzenesulfonate.

  The CMP polishing liquid concentrates 2 to 16 thus obtained are diluted with ion-exchanged water so that the abrasive grains 2 to 16 have the contents shown in Table 5, respectively. ~ 16 were obtained.

(Preparation of polishing liquid 17 for CMP)
(1) Preparation of concentrate of first liquid Abrasive particles 1 were added to ion-exchanged water previously placed in a container, and diluted so that the content of abrasive particles in the first liquid was 5.0% by mass. . The aqueous dispersion containing the cationic organic polymer particles (a) was added thereto in such an amount that the content of the cationic organic polymer particles (a) in the first liquid was 4.0% by mass. The mixture was further stirred for 30 minutes and then filtered through a polypropylene depth filter having a pore size of 5 μm to concentrate the first liquid containing the abrasive particles 1 and the cationic organic polymer particles (a). A product was prepared.

(2) Preparation of second liquid A second liquid, which is an aqueous solution containing 10% by mass of ammonium polyacrylate having a weight average molecular weight Mw of 10,000 as an anionic water-soluble compound, was prepared.

(3) Preparation of polishing liquid 17 for CMP An amount of the first liquid concentrate prepared above in an ion-exchanged water previously placed in a container so that the content of abrasive particles 1 is 0.5% by mass. Just put in. By adding the second liquid here in an amount corresponding to 5 parts by mass with respect to 100 parts by mass of the abrasive particles 1 in the first liquid, and continuing stirring for 30 minutes. 100 parts by weight of abrasive particles 1 (0.5% by weight), 80 parts by weight of cationic organic polymer particles (a) (0.4% by weight) and 5 parts by weight of polyacrylic anionic water-soluble compound A polishing slurry 17 for CMP containing 0.925 mass% of abrasive grains 17 made of ammonium acid (0.025 mass%) was obtained.

(Preparation of polishing liquids 18 to 32 for CMP)
In the preparation of the polishing liquid 17 for CMP, the types and contents of the abrasive particles and the cationic organic polymer particles in the first liquid and the anionic water-soluble compound in the second liquid were changed as shown in Table 3. In the same manner, CMP polishing liquids 18 to 32 containing abrasive grains 18 to 32 were prepared. The composition of the abrasive grains 18 to 32 was as shown in Table 4.

<< Evaluation of CMP polishing liquid >>
The following evaluation was performed for each of the polishing liquids for CMP 1 to 32 thus prepared. The evaluation results are shown in Table 5.

(Chemical mechanical polishing test)
Using CMP polishing liquids 1 to 32 prepared as described above, chemical mechanical polishing was performed using a wafer with a thermal oxide film having a diameter of 8 inches as an object to be polished under the following conditions.

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

(Evaluation of polishing rate)
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 by 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, and the results are shown in Table 5.

(Evaluation of polishing scratches)
A wafer with a thermal oxide film having a diameter of 8 inches, which is an object to be polished, was polished for 2 minutes under the chemical mechanical polishing test conditions described above. The polished surface after polishing was inspected for defects by a wafer defect inspection apparatus “KLA2351” manufactured by KLA-Tencor Corporation. First, the number of “KLA2351” 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. Subsequently, these “defects” were sequentially displayed on the display of the apparatus, and the number of scratches on the entire surface of the wafer was examined by classifying whether or not each “defect” was a scratch. 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.

(Evaluation of dispersion stability)
A polishing liquid for CMP was put in a plastic tank and allowed to stand in an environment having a temperature of 20 ° C. and a relative humidity of 50%. After 3 months, the slurry was dispersed with an ultrasonic disperser, and then the same polishing test as described above was performed.

As shown in Table 5, according to the polishing slurry for CMP of the present invention, it is shown that the polishing rate is high and the generation of polishing flaws is suppressed. Also, in the polishing slurry for CMP after standing in March, the polishing rate and the number of polishing flaws hardly change, indicating that the polishing slurry for CMP of the present invention is excellent in dispersion stability.
On the other hand, in the CMP polishing liquid of the comparative example, there were ones with a low polishing rate, and when the CMP polishing liquid after standing in March was used, the number of polishing flaws was greatly increased.

[Example 2]
This example was carried out in order to verify that abrasive grains according to the present invention were formed by aggregating abrasive particles and cationic organic polymer particles via an anionic water-soluble compound.
The CMP polishing liquid 1 prepared in Example 1 was further diluted with ion-exchanged water, applied to the collodion film and dried, and then a transmission electron microscope (TEM) photograph was taken.
By confirming the transmission electron micrograph, the abrasive grain 1 according to the present invention is formed by aggregating the abrasive particles 1 and the cationic organic polymer particles (a) via ammonium polyacrylate. I confirmed.

1 Core layer 2 Intermediate layer 3 Shell layer

Claims (3)

Abrasive particles and cationic organic polymer particles aggregated via an anionic water-soluble polymer compound, and water,
The abrasive particles have a core-shell structure;
The core layer is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Containing an oxide of at least one element selected from Yb, Lu, W, Bi, Th and an alkaline earth metal, and
A polishing slurry for CMP, wherein the shell layer contains cerium oxide. The abrasive particles further have an intermediate layer between the core layer and the shell layer; and
The intermediate layer is made of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm. 2. The polishing slurry for CMP according to claim 1, comprising an oxide of at least one element selected from Yb, Lu, W, Bi, Th, and an alkaline earth metal, and cerium oxide.   2. The second liquid containing the anionic water-soluble compound and water is mixed with the first liquid containing the abrasive particles, the cationic organic polymer particles, and water. The polishing slurry for CMP according to claim 2.

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