WO2015108113A1 - Polishing liquid production method, and polishing method - Google Patents

Abstract

　The present invention relates to a polishing liquid production method in which the pH of the polishing liquid is 4 or less, said method comprising: a step for obtaining a solution by dissolving a polymerization initiator in an aqueous solvent that does not contain inorganic acid; a step for obtaining a methacrylic acid polymer by at least polymerizing a monomer component that contains methacrylic acid in said solution; and a step for obtaining a polishing liquid by mixing the methacrylic acid polymer, a specific carboxylic acid compound, polishing particles, and a metal corrosion prevention agent.

Description

Manufacturing method and polishing method of polishing liquid

The present invention relates to a polishing liquid production method and a polishing method. Specifically, the present invention relates to a manufacturing method of a polishing liquid used for polishing in a wiring formation process of a semiconductor device and a polishing method using the polishing liquid.

In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (hereinafter referred to as “LSI”). A chemical mechanical polishing (hereinafter referred to as “CMP”) method is one of them, and is frequently used in LSI manufacturing processes (particularly, planarization of insulating materials, formation of metal plugs, formation of embedded wiring, etc. in multilayer wiring forming processes). Technology.

Recently, in order to improve the performance of LSIs, use of copper-based metals such as copper and copper alloys as wiring materials has been attempted. However, it is difficult for copper-based metals to be finely processed by a dry etching method that has been frequently used in the formation of conventional aluminum wiring. Therefore, for example, a so-called damascene method is mainly employed in which a copper alloy thin film is deposited and embedded on an insulating film in which a groove is formed in advance, and a copper alloy thin film other than the groove is removed by CMP to form a buried wiring. (For example, refer to Patent Document 1).

Here, as shown in FIG. 1 (a), the copper material is prevented from diffusing into the insulating material 2 formed on the silicon substrate 1 below the conductive material layer 5 made of copper-based metal, and the insulating material. In order to improve the adhesion between the conductive material layer 5 and the conductive material layer 5, a barrier metal film (hereinafter also referred to as "barrier metal layer 3") may be formed. In this case, it is necessary to remove the exposed barrier metal layer 3 by CMP except for the wiring portion in which the conductive substance (wiring metal) is embedded.

Therefore, the polishing step is shown as “first polishing step” in which the conductive material layer 5 is polished from the state shown in FIG. 1A to the state shown in FIG. The two-stage polishing method in which the barrier metal layer 3 and the conductive material layer 5 are polished from the state shown in FIG. 1C to the state shown in FIG. Generally applied.

By the way, with the miniaturization of design rules, each layer in the wiring forming process tends to become thinner. However, when the barrier metal layer 3 is thinned, the effect of preventing the diffusion of a conductive substance containing at least one selected from, for example, copper, copper alloys, and oxides thereof is lowered. In addition, since the wiring width is narrowed, the embedding property of the wiring part by the conductive material is lowered, and voids called voids are generated in the wiring part. Furthermore, the adhesion between the barrier metal layer 3 and the conductive material layer 5 also tends to decrease. Therefore, the metal used for the barrier metal layer 3 in FIG. 1 is a metal containing a Co (cobalt) element as a main component (referred to as a metal containing 50 mol% or more of cobalt; hereinafter referred to as “cobalt-based metal”). ) Is being considered.

From the same point of view, as shown in FIG. 2A, an intermediate layer 4 formed of a cobalt-based metal is interposed between the barrier metal layer 3 and the conductive material layer 5. . By using the intermediate layer 4 of the cobalt-based metal, the diffusion of the conductive substance can be suppressed. Furthermore, since cobalt has a high affinity with copper, which is widely used as a conductive material, the embedding property of copper in the wiring portion is improved. Furthermore, adhesion with the copper layer can be supplemented. The intermediate layer 4 here is also a barrier metal layer in a broad sense. Hereinafter, for the sake of simplicity, the term “barrier metal layer” includes the intermediate layer 4 within the range.

When a cobalt-based metal is used as a barrier metal layer in an LSI, it is necessary for the metal polishing liquid to be able to remove excess cobalt-based metal. Various metal polishing liquids are known. On the other hand, when polishing is attempted using a conventional metal polishing liquid, any metal can be suitably removed. Not exclusively. Conventional metal polishing liquids are known for polishing metals such as copper, tantalum, titanium, tungsten, and aluminum (targets to be removed as extra parts), but cobalt-based metals are target for polishing. There is not much known polishing liquid.

By the way, cobalt-based metals are more easily corroded (strongly corrosive) than conductive materials such as copper that have been conventionally used as wiring metals. Therefore, if the conventional polishing liquid is used as it is, the cobalt metal may be excessively eroded (etched) or a slit may be formed in the wiring layer. Therefore, there is a concern that the cobalt metal does not function as a barrier metal layer and the conductive metal ions diffuse. If metal ions diffuse into the insulating material, the semiconductor device is more likely to short. On the other hand, in order to prevent this, if an anticorrosive having a strong anticorrosive action is added or the amount of the anticorrosive added is increased, there is a problem that the overall polishing rate is lowered.

Polishing using a specific metal anticorrosive agent which is a 4-membered to 6-membered heterocyclic compound containing two or more double bonds and containing one or more nitrogen atoms in order to cope with such a problem. Known are liquids (see, for example, Patent Document 2), polishing liquids using phthalic acid compounds, isophthalic acid compounds, and dicarboxylic acid compounds (for example, see Patent Document 3).

Further, in the second polishing step, when the polishing rate of the silicon dioxide film, which is an interlayer insulating film formed other than the metal buried portion, is also high, the phenomenon that the thickness of the wiring with the interlayer insulating film becomes thin (hereinafter, “ And the phenomenon that the interlayer insulating film in the vicinity of the wiring metal part is locally scraped (hereinafter referred to as “seam”) occurs, and the flatness deteriorates. As a result, problems such as an increase in wiring resistance occur, so that the occurrence of erosion and seam is required to be reduced as much as possible. Examples of the interlayer insulating film include a silicon dioxide film, an organosilicate glass which is a low-k (low dielectric constant) film, a wholly aromatic ring-based low-k film, and the like.

As a method for reducing the generation of erosion and seam, a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid are used to protect the surface of the wiring metal (for example, copper). It is known to use a polishing liquid comprising the same (for example, see Patent Document 4).

JP-A-2-278822 JP 2011-91248 A JP2013-42123A JP 2013-62516 A

However, as a result of investigations by the inventors, it has been found that the polishing liquid containing the methacrylic acid polymer increases the etching rate with respect to the cobalt metal. If the etching rate for the cobalt metal is high, when the cobalt metal is used as the barrier metal layer, the cobalt metal may be excessively eroded or a slit may be formed in the wiring layer. Therefore, as described above, there is a problem that the cobalt-based metal does not function as a barrier metal layer.

An object of the present invention is to provide a method for producing a polishing liquid that is excellent in planarizing the surface of a substrate and has a low etching rate for a cobalt-based metal, and a polishing method using the polishing liquid obtained thereby.

Another object of the present invention is to provide a polishing liquid manufacturing method that suppresses the generation of erosion and seam while maintaining a good polishing rate for an interlayer insulating film, and has a high leveling ability of the surface to be polished, and the manufacturing method thereof. An object of the present invention is to provide a polishing method using a polishing liquid.

As a result of examining the cause of the problem that the cobalt-based metal does not function as a barrier metal layer in detail, improving the synthesis method of the methacrylic acid-based polymer is an important point for solving the above problem. The inventors found that. For example, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], which is a water-soluble azo polymerization initiator, is used as a polymerization initiator for the synthesis of the polymer. It can be dissolved in an acidic aqueous solution, and is generally dissolved using an inorganic acid such as sulfuric acid. Therefore, the polymer contains several moles of inorganic acid. It has been found that when a conventional polishing liquid using a polymer containing such an inorganic acid (such as sulfuric acid) is used, the cobalt-based metal is excessively eroded (etched) or slits are formed in the wiring layer.

Specific means for solving the above-mentioned problems are as follows <1> to <17>.
<1> A step of obtaining a solution by dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid, a step of obtaining a methacrylic acid polymer by polymerizing a monomer component containing at least methacrylic acid in the solution, and a methacrylic acid type And a step of mixing a polymer, a carboxylic acid compound, abrasive particles and a metal anticorrosive to obtain a polishing liquid, wherein the carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, or a dicarboxylic acid represented by the following general formula (I) Containing at least one selected from the group consisting of acid compounds, their salts, and acid anhydrides of phthalic acid compounds and acid anhydrides of dicarboxylic acid compounds represented by the following general formula (I), and the pH of the polishing liquid The manufacturing method of polishing liquid whose is 4 or less.
HOOC-R-COOH (I)
[In the above general formula (I), R has 3 to 10 carbon atoms and contains only carbon and hydrogen as constituent elements. ]

According to the polishing liquid thus obtained, it is possible to moderately suppress the corrosion of the cobalt-based metal and reduce the occurrence of erosion and seam while maintaining a good polishing rate for the cobalt-based metal.

<2> The production method according to <1>, wherein the aqueous solvent is water or water and an organic acid.

<3> The method according to <1> or <2> above, wherein the polishing liquid is a polishing liquid for chemical mechanical polishing (CMP) a substrate containing cobalt (cobalt element).

<4> The above <1> to <1>, wherein the methacrylic acid polymer is at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. 3> The manufacturing method as described in any one of 3>.

Thereby, a polishing liquid capable of more effectively polishing the interlayer insulating film can be obtained.

<5> The production method according to any one of <1> to <4>, wherein the metal anticorrosive contains a compound having a triazole skeleton.

Thereby, a polishing liquid capable of more effectively suppressing the corrosiveness can be obtained.

<6> The method according to any one of <1> to <5>, wherein in the step of obtaining a polishing liquid, an organic solvent is further mixed to obtain the polishing liquid.

Thereby, when the film to be polished includes a layer other than the cobalt-based metal, wettability with respect to the layer other than the cobalt-based metal is improved, so that a polishing liquid capable of further improving the polishing rate can be obtained.
<7> The production method according to any one of <1> to <6>, wherein in the step of obtaining a polishing liquid, an oxidizing agent is further mixed to obtain the polishing liquid.

Thereby, when the film to be polished includes a metal layer other than the cobalt-based metal, a polishing liquid capable of further improving the polishing rate of the metal layer other than the cobalt-based metal can be obtained.

<8> In the step of obtaining a polishing liquid, the polishing is performed by mixing a methacrylic acid polymer, a first liquid containing a carboxylic acid compound, abrasive particles and a metal anticorrosive, and a second liquid containing an oxidizing agent. The production method according to <7>, wherein a liquid is obtained.

<9> A step of obtaining a solution by dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid, a step of obtaining a methacrylic acid polymer by polymerizing a monomer component containing at least methacrylic acid in the solution, and a methacrylic acid type A step of mixing a polymer, a carboxylic acid compound, abrasive particles and a metal anticorrosive to obtain a polishing liquid, a step of preparing a substrate containing a cobalt-based metal, a step of chemically mechanically polishing the substrate using the polishing solution, The carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the above general formula (I), a salt thereof, and an acid anhydride of the phthalic acid compound and the above general formula (I) A polishing method comprising at least one selected from the group consisting of acid anhydrides of dicarboxylic acid compounds represented, wherein the pH of the polishing liquid is 4 or less.

<10> The polishing method according to <9>, wherein the aqueous solvent is water or water and an organic acid.

<11> The above <9> or <10, wherein the methacrylic acid polymer is at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. > Polishing method.

<12> The polishing method according to any one of <9> to <11>, wherein the metal anticorrosive contains a compound having a triazole skeleton.

<13> The polishing method according to any one of <9> to <12>, wherein in the step of obtaining a polishing liquid, an organic solvent is further mixed to obtain the polishing liquid.

<14> The polishing method according to any one of <9> to <13>, wherein in the step of obtaining a polishing liquid, an oxidizing agent is further mixed to obtain the polishing liquid.

<15> In the step of obtaining a polishing liquid, a first liquid containing a methacrylic acid polymer, a carboxylic acid compound, abrasive particles and a metal anticorrosive and a second liquid containing an oxidizing agent are mixed to obtain the polishing liquid. The polishing method according to <14>, obtained.

According to the polishing method of the present invention, it becomes possible to polish a film to be polished containing cobalt element while suppressing excessive corrosion.

According to the present invention, a methacrylic acid polymer obtained without using an inorganic acid as a raw material at the time of synthesis, a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the above general formula (I), and salts thereof And at least one carboxylic acid compound selected from the group consisting of an acid anhydride of a phthalic acid compound and an acid anhydride of a dicarboxylic acid compound represented by the above general formula (I), and having a pH of The manufacturing method of the polishing liquid which is 4 or less can be provided. By using the polishing liquid obtained by the production method, it is possible to moderately suppress the corrosion of the cobalt-based metal while maintaining a good polishing rate for the cobalt-based metal, and while maintaining a good polishing rate for the interlayer insulating film. Generation of erosion and seam can be suppressed. That is, according to the present invention, it is possible to provide a method for producing a polishing liquid having a high leveling ability of the surface to be polished and a method for polishing a substrate using the polishing liquid obtained thereby.

It is a schematic cross section which shows the wiring formation process in the conventional damascene process. It is a schematic cross section which shows the wiring formation process in a damascene process when there exists an intermediate | middle layer of a cobalt-type metal. It is sectional drawing which shows an example of the board | substrate after grinding | polishing by the grinding | polishing method of this embodiment. It is a cross-sectional schematic diagram which shows the striped pattern and the erosion which the wiring metal part and the interlayer insulation film part arranged in the pattern board | substrate with a copper wiring alternately. It is a cross-sectional schematic diagram which shows the part and seam where the wiring metal part and the interlayer insulation film part were located in a line in a pattern board with copper wiring.

In this specification, the term “process” includes not only an independent process but also a process that cannot be clearly distinguished from other processes and in which the intended purpose can be achieved. . A numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, the content of each component in the polishing liquid means the total amount of the plurality of substances present in the polishing liquid unless there is a specific notice when there are a plurality of substances corresponding to each component in the polishing liquid.

Hereinafter, preferred embodiments of a production method of the present invention, a polishing liquid obtained by the production method (hereinafter also simply referred to as “polishing liquid”), and a substrate polishing method using the polishing liquid will be described in detail.

[Production method of polishing liquid]
The production method of this embodiment includes a step of obtaining a solution by dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid, and a step of obtaining a methacrylic acid polymer by polymerizing a monomer component containing at least methacrylic acid in the solution. And a step of mixing a methacrylic acid polymer, a carboxylic acid compound, abrasive particles, and a metal anticorrosive to obtain a polishing liquid.

The operations of “dissolution”, “polymerization”, and “mixing” in each step can be appropriately performed by those skilled in the art. Therefore, the compounds defined in each step will be described in detail in the next section “Polishing liquid”.

[Polishing liquid]
The polishing liquid obtained by the production method of the present embodiment is represented by a methacrylic acid polymer obtained without using an inorganic acid as a raw material during synthesis, a phthalic acid compound, an isophthalic acid compound, and the following general formula (I). Dicarboxylic acid compounds, salts thereof (that is, salts of phthalic acid compounds, isophthalic acid compounds and dicarboxylic acid compounds represented by the following general formula (I)), and acid anhydrides of phthalic acid compounds and the following general formula (I) It contains at least one carboxylic acid compound selected from the group consisting of acid anhydrides of dicarboxylic acid compounds represented by the formula: abrasive particles, metal anticorrosive, and water, and has a pH of 4 or less. Features. Such a polishing liquid can be suitably used, for example, for chemical mechanical polishing of a substrate containing cobalt element.
HOOC-R-COOH (I)
[In the above general formula (I), R has 3 to 10 carbon atoms and contains only carbon and hydrogen as constituent elements. ]

<Carboxylic acid compound>
The polishing liquid of this embodiment includes a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the above general formula (I) (hereinafter, also referred to as “specific dicarboxylic acid compound”), a salt thereof, and phthalic acid. A carboxylic acid compound that is at least one selected from the group consisting of an acid anhydride of an acid compound and an acid anhydride of the dicarboxylic acid compound (hereinafter also referred to as “specific carboxylic acid compound”). The said specific carboxylic acid compound can be used individually by 1 type or in mixture of 2 or more types.

There are countless carboxylic acids and carboxylic acid derivatives. However, by selecting the specific carboxylic acid compound from these, the etching rate for the same layer is controlled while maintaining a good polishing rate for the cobalt-based metal. Thereby, corrosion of a cobalt-type metal is suppressed and a favorable grinding | polishing surface can be obtained. Even under more severe conditions (for example, 60 ° C.), the etching rate of the cobalt-based metal is more effectively suppressed, and excellent corrosion inhibition is achieved. Here, being excellent in corrosion inhibition means that the cobalt-based metal is etched on the surface to be polished or slits in the wiring layer are effectively suppressed.

The reason why such an effect is obtained is not clear, but the present inventor presumes as follows. That is, it is considered that the specific carboxylic acid compound functions as a metal solubilizer and has an effect of improving the polishing rate for the cobalt-based metal. At the same time, it is considered that the two carboxy groups of the specific carboxylic acid compound are chelated to the cobalt atom so as to form a cyclic structure, thereby forming a stable complex state. . For this reason, it is presumed that the etching rate of the cobalt-based metal is controlled and corrosion on the polished surface is suppressed. In addition, there is a possibility that the metal anticorrosive described later contributes to the formation of this stable complex state.

The specific carboxylic acid compound is composed of a specific dicarboxylic acid compound, a salt thereof, and an acid anhydride thereof (limited to an acid anhydride) from the viewpoints of polishing rate with respect to the cobalt layer, controllability of etching rate, and corrosion inhibition. Selected from the group. With acidic compounds other than the specific carboxylic acid compound, it is difficult to achieve both good polishing rate for the cobalt layer and suppression of the etching rate of the cobalt layer. This is presumably because the formation of a stable complex state is important in the present embodiment as described above, and the three-dimensional structure of the acidic compound is an important factor. Moreover, even if it contains the said specific carboxylic acid compound, when it contains other acidic compounds other than that, the etching rate of a cobalt layer may raise notably. This is considered to be because the etching effect of the cobalt layer by other acidic compounds has priority over the formation of the complex state as described above.

In the first aspect of the polishing liquid of this embodiment, the carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the above general formula (I), a salt thereof, or a phthalic acid compound. It consists of at least one selected from the group consisting of acid anhydrides and acid anhydrides of dicarboxylic acid compounds represented by the above general formula (I). However, the carboxylic acid compound may contain other carboxylic acid compounds (including salts thereof and acid anhydrides) as long as the effects of the present embodiment are not significantly impaired.

However, the carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the above general formula (I), a salt thereof, an acid anhydride of the phthalic acid compound, or the above general formula (I). It is preferable to be substantially composed of a specific carboxylic acid compound which is at least one selected from the group consisting of acid anhydrides of the dicarboxylic acid compounds represented. Here, “substantially” means that a sufficient amount of the specific carboxylic acid compound is contained in the polishing liquid to such an extent that the effect of the polishing liquid of the present embodiment is not significantly impaired. Means that the content of the other carboxylic acid compound is 10% by mass or less based on the total mass of the specific carboxylic acid compound. Furthermore, the content of the other carboxylic acid compound is preferably 5% by mass or less, and more preferably 1% by mass or less, based on the total mass of the specific carboxylic acid compound.

Among the specific dicarboxylic acid compounds, the phthalic acid compound includes at least one of phthalic acid (benzene-1,2-dicarboxylic acid) and a phthalic acid derivative having one or more substituents on the benzene ring. Examples of the substituent include a methyl group, an amino group, and a nitro group. Among these, at least one of a nitro group and a methyl group is preferable.

Specific examples of the phthalic acid compound include phthalic acid; alkylphthalic acid such as 3-methylphthalic acid and 4-methylphthalic acid; aminophthalic acid such as 3-aminophthalic acid and 4-aminophthalic acid; 3-nitrophthalic acid, 4 -Nitrophthalic acid such as nitrophthalic acid. Among these, a phthalic acid compound having an alkyl group as a substituent (for example, methylphthalic acid) is preferable, at least one of 3-methylphthalic acid and 4-methylphthalic acid is more preferable, and 4-methylphthalic acid is particularly preferable. The phthalic acid compound may be used as an acid anhydride or a salt.

The isophthalic acid compound includes at least one of isophthalic acid (benzene-1,3-dicarboxylic acid) and an isophthalic acid derivative having one or more substituents on the benzene ring. Examples of the substituent include a nitro group, a methyl group, an amino group, and a hydroxy group. Among these, a methyl group is preferable.

Specific examples of the isophthalic acid compound include isophthalic acid and 5-nitroisophthalic acid. The isophthalic acid compound may be used as a salt.

The R part of the dicarboxylic acid compound represented by the general formula (I) is a divalent group having 3 to 10 carbon atoms and containing only carbon (C) and hydrogen (H) as constituent elements. In addition, the said carbon number is carbon number of R part, and the carbon atom contained in a carboxylic acid group is not counted as said carbon number. The R portion may be cyclic, linear or branched. Among these, linear is preferable. From the viewpoints of polishing rate and etching rate control for cobalt-based metals, and corrosion inhibition, the number of carbons is preferably from 3 to 8, and more preferably from 3 to 6. The dicarboxylic acid compound may be used as an acid anhydride or a salt depending on the number of carbon atoms.

Specific examples of the dicarboxylic acid compound having 3 to 10 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, itaconic acid and the like. Among these, adipic acid, pimelic acid and itaconic acid are preferable, and pimelic acid is more preferable.

The content of the carboxylic acid compound is preferably in the range of 0.001 to 10% by mass based on the total mass of the polishing liquid. By adjusting the content of the carboxylic acid compound to the above range, a layer other than the cobalt metal provided in the vicinity of the cobalt metal (for example, provided in the vicinity of the intermediate layer 4 shown in FIG. 2A). A good polishing rate of the conductive material layer 5 such as copper, such as copper, and the barrier metal layer 3 can be obtained.

The content of the carboxylic acid compound is more preferably 0.01% by mass or more, and further preferably 0.02% by mass or more from the viewpoint of polishing rate. In addition, the content of the dicarboxylic acid is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass from the viewpoints of the etching inhibitory effect and corrosion inhibitory effect on the cobalt-based metal. The following are particularly preferred:

From the viewpoint of polishing rate, the polishing liquid is represented by phthalic acid, alkylphthalic acid, aminophthalic acid, nitrophthalic acid, isophthalic acid, 5-nitroisophthalic acid, and the above general formula (I) as a carboxylic acid compound, and R Preferably contains 0.01% by mass or more of at least one selected from the group consisting of dicarboxylic acid compounds having 3 to 8 carbon atoms, and salts and acid anhydrides thereof (limited to those that become acid anhydrides). .

In addition, from the viewpoint of suppressing the etching effect on the cobalt-based metal, the polishing liquid contains phthalic acid, alkylphthalic acid, aminophthalic acid, nitrophthalic acid, isophthalic acid, 5-nitroisophthalic acid, and the above general formula (I) as a carboxylic acid compound. And at least one selected from the group consisting of dicarboxylic acid compounds in which R is a straight chain having 3 to 8 carbon atoms, and salts and acid anhydrides thereof (limited to acid anhydrides). It is preferable to contain 1.0 mass% or less.

The salt of the carboxylic acid compound is not particularly limited, and examples thereof include a salt of the carboxylic acid compound and an alkali metal, alkaline earth metal, halide or the like. However, for example, when the substrate to be polished is a silicon substrate including an integrated circuit element, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable. Preference is given to other than salts with earth metals or halides.

<Methacrylic acid polymer>
A methacrylic acid polymer obtained by dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid to obtain a solution, and polymerizing a monomer component containing at least methacrylic acid in the solution to obtain a methacrylic acid polymer. Is estimated to be able to suppress corrosion on cobalt-based metals as compared with methacrylic acid-based polymers obtained using an aqueous solvent containing an inorganic acid. Here, the aqueous solvent is not particularly limited as long as it can dissolve the polymerization initiator, but water or a solvent composed of water and an organic acid described later is preferable.

In the step of obtaining the methacrylic acid polymer of the present embodiment, there are two methods, a case where a water-soluble polymerization initiator is used and a case where a polymerization initiator which dissolves in a monomer component containing methacrylic acid is used. When using the latter polymerization initiator that dissolves in the monomer component containing methacrylic acid, first dissolve the polymerization initiator in the monomer component containing methacrylic acid, and then dissolve the polymerization initiator in an aqueous solvent. By adding dropwise a monomer component containing methacrylic acid, a polymer can be obtained while dissolving the polymerization initiator in an aqueous solvent.

Examples of the polymerization initiator for synthesizing the polymer include a water-soluble azo polymerization initiator and an azo polymerization initiator dissolved in a monomer component containing methacrylic acid. For example, water-soluble azobis polymerization initiators include 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [N- (2-carboxyethyl) -2- Methyl propionamidine], 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropanamide], salts thereof and the like. Examples of the azo polymerization initiator dissolved in the monomer component containing methacrylic acid include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), these Examples include salts.

The salt of the azo polymerization initiator is not particularly limited. However, when the substrate to be polished is a silicon substrate including an integrated circuit element as described above, the salt with an alkali metal, alkaline earth metal, halide, or the like is used. Other than salts are preferred.

Polymerization initiators such as 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropanamide] and the like In order to dissolve in an aqueous solvent, it is necessary to make the aqueous solvent acidic. By selecting an acid other than the inorganic acid as the acid added to make the aqueous solvent acidic, the etching rate for the same layer can be controlled while maintaining a good polishing rate for the cobalt-based metal. Therefore, corrosion of the same layer is suppressed and a good polished surface can be obtained. Even under more severe conditions (for example, 60 ° C.), the etching rate of the cobalt-based metal is more effectively suppressed, and excellent corrosion inhibition is achieved.

The amount of the polymerization initiator used is not particularly limited, but it is preferably added so that the molar ratio of the monomer component to the polymerization initiator is about monomer component: polymerization initiator = 100 mol: about 0.2 to 4 mol.

The polymer contained in the polishing liquid of this embodiment needs to be a methacrylic acid polymer obtained without using an inorganic acid as a raw material during the synthesis.
The acid added to make the aqueous solvent acidic is not particularly limited as long as it is an acid other than the inorganic acid in that it can suppress the corrosion of the cobalt metal. Such acids include 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropanamide] and the like For example, formic acid, acetic acid, propionic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid. And organic acids such as maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, methanesulfonic acid and p-phenolsulfonic acid. Among these, acetic acid, glycolic acid, glutaric acid, p-phenolsulfonic acid, methanesulfonic acid, malic acid, and the like are preferable because corrosion of cobalt-based metals can be effectively suppressed. The amount of acid used is not particularly limited as long as it is an amount sufficient to dissolve the polymerization initiator in the aqueous solvent, but is preferably about equimolar with the polymerization initiator.

In addition, the above polymer has higher adsorptivity to copper than other water-soluble polymers. Since the polymer has a high adsorptivity to copper particularly in a portion having a high wiring density and is excellent in the protection performance of copper, it is estimated that it is possible to reduce the occurrence of erosion and seam when polishing a film to be polished. The The methacrylic acid polymer is preferably at least one selected from a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid.

When the methacrylic acid polymer is a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid, the ratio of methacrylic acid to the total amount of the monomer is preferably 40 mol% or more and less than 100 mol%, more preferably 50 mol%. It is more than 100 mol%, more preferably 60 mol% or more and less than 100 mol%, particularly preferably 70 mol% or more and less than 100 mol%. By making the ratio of the methacrylic acid 40 mol% or more, the generation of erosion and seam can be effectively suppressed, and the flatness of the surface to be polished can be easily improved.

The weight average molecular weight of the methacrylic acid polymer is preferably 3000 or more, more preferably 5000 or more. By setting the weight average molecular weight of the methacrylic acid polymer to 3000 or more, generation of erosion and seam is effectively suppressed, and the flatness of the surface to be polished can be easily improved. The upper limit of the weight average molecular weight is not particularly defined, but is preferably 5 million or less from the viewpoint of solubility. The weight average molecular weight is preferably 1,000,000 or less from the viewpoint of ease of synthesis, control of molecular weight, etc., and from the viewpoint of excellent solubility in water and increasing the degree of freedom of addition. More preferably, it is 10,000 or less.

The weight average molecular weight of the methacrylic acid polymer can be measured by gel permeation chromatography using a standard polystyrene calibration curve. Specifically, for example, measurement can be performed by size exclusion chromatography using a calibration curve prepared with a sodium polyacrylate standard substance manufactured by Polymer Laboratories under the following measurement conditions.
Column: Shodex Asahipak GS-520HQ + 620HQ manufactured by Showa Denko KK
Pump: Hitachi, Ltd. L-71000
Eluent: 50 mM Na ₂ HPO ₄ aq. / CH ₃ CN = 90/10
Flow rate: 0.6 mL / min
Detector: L-3300 differential refractometer manufactured by Hitachi, Ltd. Data processing: D-2520 GPC integrator manufactured by Hitachi, Ltd. Sample concentration: 10 mg / mL
Injection volume: 5 μL

Examples of the monomer copolymerizable with methacrylic acid include acrylic acid, crotonic acid, vinyl acetic acid, tiglic acid, 2-trifluoromethyl acrylic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, mesaconic acid, and glucone. Carboxylic acids such as acids; sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate And acrylic acid esters such as propyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate; and salts thereof such as ammonium salts, alkali metal salts and alkylamine salts thereof. When the substrate to be applied is a silicon substrate for a semiconductor integrated circuit, an ammonium salt is preferable among the salts.

As described above, a higher content of methacrylic acid in a methacrylic acid polymer is effective in reducing erosion and seam generation. However, if attention is paid to the fact that defects such as generation of organic residues and generation of scratches on the polished surface after polishing can be reduced, the methacrylic acid polymer may be copolymerized with methacrylic acid and the methacrylic acid. It is preferred to use copolymers with possible monomers. As the monomer copolymerizable with methacrylic acid, acrylic acid and acrylic acid esters are more preferable in that they are effective in reducing the above-mentioned defects, and further in balance with reduction of erosion and seam generation. Acrylic acid and acrylic acid esters are more preferred.

The content of the methacrylic acid polymer is preferably 0.001 to 15% by mass, more preferably 0.01 to 5% by mass, based on the total mass of the polishing liquid. By setting the content of the methacrylic acid polymer to 0.001% by mass or more, generation of erosion and seam is effectively suppressed, and the flatness of the surface to be polished can be easily improved. In addition, by controlling the content to 15% by mass or less, it is easy to maintain the stability of the abrasive particles contained in the polishing liquid and improve the dispersibility of the abrasive particles while suppressing the generation of erosion and seam.

As explained so far, the polishing liquid of the present embodiment preferably satisfies at least one of the following (1) and (2) from the viewpoint of effectively suppressing the generation of erosion and seam.
(1) To increase the ratio of methacrylic acid to the total amount of monomers constituting the methacrylic acid polymer.
(2) Use acrylic acid or acrylic acid esters as a monomer component to be copolymerized with methacrylic acid.

Further, satisfying the above (1) and (2) is preferable in that defects such as scratches and organic residues can be reduced while suppressing generation of erosion and seam. That is, the methacrylic acid polymer (including both homopolymers and copolymers) is preferably a copolymer of methacrylic acid and acrylic acid, or a copolymer of methacrylic acid and acrylic acid esters. Among these, the methacrylic acid polymer is preferably a copolymer of methacrylic acid and acrylic acid or a copolymer of methacrylic acid and acrylic acid ester from the viewpoint of reducing the occurrence of erosion and seam.
The ratio of methacrylic acid to the total amount of monomers constituting the methacrylic acid polymer is preferably 70 mol% or more and less than 100 mol%, more preferably 80 mol% or more, and still more preferably 90 mol% or more. . Moreover, in order to suppress defects effectively, the ratio of methacrylic acid to the total amount of the monomer is preferably 99 mol% or less, and more preferably 95 mol% or less.

The polishing liquid of this embodiment can also be obtained by mixing two liquids divided into a slurry containing at least abrasive particles and an additive liquid containing at least a methacrylic acid polymer. By doing so, it is possible to avoid the problem of stability of the abrasive particles which occurs when a large amount of methacrylic acid polymer is added. In the case of dividing into two liquids, the slurry may contain a methacrylic acid polymer. In this case, the content of the methacrylic acid polymer in the slurry is in a range that does not impair the dispersibility of the abrasive particles.

<Abrasive particles>
The polishing liquid of this embodiment preferably contains abrasive particles from the viewpoint of obtaining a good polishing rate for the barrier layer and the interlayer insulating film. The abrasive particles that can be used include at least one selected from the group consisting of silica, alumina, zirconia, ceria, titania, germania, and modified products thereof. The modified product is obtained by modifying the surface of abrasive particles such as silica, alumina, zirconia, ceria, titania and germania with an alkyl group.

The method of modifying the surface of the abrasive particles with an alkyl group is not particularly limited, and examples thereof include a method of reacting a hydroxyl group present on the surface of the abrasive particle with an alkoxysilane having an alkyl group. The alkoxysilane having an alkyl group is not particularly limited, but monomethyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, monoethyltrimethoxysilane, diethyldimethoxysilane, triethylmonomethoxysilane, monomethyltriethoxysilane, dimethyl Examples include diethoxysilane and trimethylmonoethoxysilane. There is no restriction | limiting in particular as a reaction method. For example, both simply react with a polishing liquid containing abrasive particles and alkoxysilane at room temperature. However, heating may be performed to accelerate the reaction.

Among the above abrasive particles, colloidal silica and / or colloidal alumina having a good dispersion stability in the polishing liquid, a small number of polishing scratches (scratches) generated by CMP, and an average particle diameter of 200 nm or less are preferable, Colloidal silica and / or colloidal alumina having an average particle size of 100 nm or less is more preferable.

The “average particle diameter” of the abrasive particles means the average secondary particle diameter of the abrasive particles. The average particle size is a value of D50 (median diameter of volume distribution, cumulative median value) obtained by measuring the polishing liquid with a dynamic light scattering particle size distribution analyzer (for example, COULTER Electronics, trade name: COULTER N4 SD). Say.

Specifically, the average particle diameter can be measured by the following procedure. First, 100 μL of polishing liquid (L represents liter, the same applies hereinafter) is weighed, and the content of abrasive particles is about 0.05% by mass (transmittance (H) during measurement is about 60 to 70%). Dilute with ion-exchanged water to obtain a diluted solution. And an average particle diameter can be measured by throwing a dilution liquid into the sample tank of a dynamic light scattering type particle size distribution analyzer, and reading the value displayed as D50.

The content of abrasive particles is preferably 0.01 to 50% by mass, more preferably 0.02 to 30% by mass, and particularly preferably 0.05 to 20% by mass with respect to the total mass of the polishing liquid. When the content of the abrasive particles is 0.01% by mass or more, the polishing rate is improved, and when the content is 50% by mass or less, the generation of scratches is easily suppressed.

As the abrasive particles, abrasive particles whose surfaces are modified with anionic groups or cationic groups may be used. Thereby, since the surface potential of the abrasive particles is negatively or positively charged, there is a tendency that aggregation of the abrasive particles is easily suppressed. Examples of the modification with an anionic group include sulfonic acid modification and aluminate modification. Examples of the modification with a cationic group include modification using an amine compound or the like.

<Metal anticorrosive>
There is no restriction | limiting in particular as a metal anticorrosive agent contained in the polishing liquid of this embodiment, Any conventionally well-known thing can be used as a compound which has the anticorrosion action with respect to a metal. Specifically, the metal anticorrosive is at least one selected from the group consisting of triazole compounds, pyridine compounds, pyrazole compounds, pyrimidine compounds, imidazole compounds, guanidine compounds, thiazole compounds, tetrazole compounds, triazine compounds, and hexamethylenetetramine. Can be used. Here, “XX compound” is a general term for compounds having an XX skeleton, and for example, a triazole compound means a compound having a triazole skeleton.

The metal anticorrosive can be used alone or in combination of two or more. The content of the metal anticorrosive is 0.001 to 10% by mass with respect to the total mass of the polishing liquid in that a good polishing rate can be obtained for a film to be polished containing cobalt element. preferable. From the same viewpoint, the content of the metal anticorrosive is more preferably 0.01% by mass or more, and further preferably 0.02% by mass or more. Further, from the same viewpoint, the content of the metal anticorrosive is more preferably 5.0% by mass or less, and further preferably 0.5% by mass.

When the metal anticorrosive is combined with the carboxylic acid compound, the etching rate of the cobalt-based metal can be remarkably suppressed even under severe temperature conditions (for example, 60 ° C.). That is, by the above combination, corrosion of the cobalt metal can be suppressed while polishing the cobalt metal at an appropriate speed. This is considered to be because, for example, the metal anticorrosive exhibits an excellent function as a complex-forming agent and a film protective agent in the presence of the specific dicarboxylic acid compound.

Also, the metal anticorrosive agent forms a protective film against a wiring metal such as a copper-based metal, thereby suppressing the etching of the wiring metal and easily reducing the roughness of the surface to be polished.

From this point of view, among the metal anticorrosives, at least one selected from the group consisting of triazole compounds, pyridine compounds, imidazole compounds, tetrazole compounds, triazine compounds and hexamethylenetetramine is preferable. Triazole compounds such as triazolo [4,5-b] pyridin-3-ol, 1-hydroxybenzotriazole, 1H-1,2,3-triazolo [4,5-b] pyridine, benzotriazole, 3-hydroxypyridine More preferred is at least one selected from the group consisting of benzimidazole, 5-amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine and hexamethylenetetramine.

The ratio of the carboxylic acid compound to the metal anticorrosive in the polishing liquid (carboxylic acid compound / metal anticorrosive) is in the range of 10/1 to 1/5 in terms of mass ratio from the viewpoint of favorably controlling the etching rate and the polishing rate. It is preferably in the range of 7/1 to 1/5, more preferably in the range of 5/1 to 1/5, and more preferably in the range of 5/1 to 1/1. Is particularly preferred.

Further, in the polishing liquid, the ratio of the carboxylic acid compound to the metal anticorrosive (carboxylic acid compound / metal anticorrosive) is 10/1 to 1/5 from the viewpoint of controlling the etching rate and the polishing rate satisfactorily. The ratio of the carboxylic acid compound to at least one metal anticorrosive selected from the group consisting of triazole compounds, pyridine compounds, imidazole compounds, tetrazole compounds, triazine compounds and hexamethylenetetramine (carboxylic acid compound / metal anticorrosion) Agent) is more preferably 5/1 to 1/5, the carboxylic acid compound, 3H-1,2,3-triazolo [4,5-b] pyridin-3-ol, 1-hydroxybenzotriazole Triazolation of 1H-1,2,3-triazolo [4,5-b] pyridine, benzotriazole, etc. At least selected from the group consisting of 3-hydroxypyridine, benzimidazole, 5-amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine and hexamethylenetetramine It is more preferable that the ratio (carboxylic acid compound / metal anticorrosive agent) to one type of metal anticorrosive agent is 5/1 to 1/1.

<Oxidizing agent>
The polishing liquid preferably further contains at least one oxidizing agent (metal oxidizing agent). By further containing an oxidizing agent, the polishing rate of layers other than the cobalt-based metal can be further improved. There is no restriction | limiting in particular in the said oxidizing agent, It can select suitably from the oxidizing agent used normally. Specific examples include hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, ozone water, etc. Among these, hydrogen peroxide is preferable. These oxidizing agents can be used alone or in combination of two or more.

When the polishing liquid contains an oxidizing agent, the content of the oxidizing agent is preferably 0.01 to 50% by mass with respect to the total mass of the polishing liquid. The content is more preferably 0.02% by mass or more, and still more preferably 0.05% by mass or more from the viewpoint of preventing metal oxidation from becoming insufficient and reducing the polishing rate. Moreover, 30 mass% or less is more preferable, and 15 mass% or less is still more preferable at the point which can prevent that a surface to be polished becomes rough. Note that an oxidizing agent that is generally available as an aqueous solution, such as aqueous hydrogen peroxide, may be prepared so that the content of the oxidizing agent contained in the aqueous solution falls within the above range in the polishing liquid.

<Organic solvent>
The polishing liquid may further contain an organic solvent. By adding an organic solvent, the wettability of a layer other than the cobalt-based metal provided in the vicinity of the cobalt-based metal can be improved, and the polishing rate can be further improved. Although there is no restriction | limiting in particular as said organic solvent, A water-soluble thing is preferable. Here, water-soluble is defined as one that dissolves at least 0.1 g at 25 ° C. with respect to 100 g of water.

Examples of the organic solvent include carbonate solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactone solvents such as butyrolactone and propyl lactone; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, Glycol solvents such as triethylene glycol and tripropylene glycol; ether solvents such as tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, n -Butanol, n-pen Alcohol solvents such as diol, n-hexanol, isopropanol, 3-methoxy-3-methyl-1-butanol; ketone solvents such as acetone and methyl ethyl ketone; and others such as dimethylformamide, N-methylpyrrolidone, ethyl acetate, ethyl lactate, and sulfolane The organic solvent of these is mentioned.

The organic solvent may be a glycol solvent derivative. For example, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether , Dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether Glycol monoether solvents such as tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether; ethylene glycol dimethyl ether, propylene Glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol diethyl Ether, dipropylene glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, triethylene glycol dipropyl ether And glycol ether solvents such as tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, and tripropylene glycol dibutyl ether.

Among these, at least one selected from the group consisting of a glycol solvent, a glycol solvent derivative, an alcohol solvent, and a carbonate ester solvent is preferable, and at least one selected from an alcohol solvent is more preferable. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

When the polishing liquid contains an organic solvent, the content of the organic solvent is preferably 0.1 to 95% by mass with respect to the total mass of the polishing liquid. The content of the organic solvent is more preferably 0.2% by mass or more, and still more preferably 0.5% by mass or more in terms of preventing the wettability of the polishing liquid to the substrate from being lowered. Further, the content is more preferably 50% by mass or less, and further preferably 10% by mass or less, in terms of facilitating preparation, use, waste liquid treatment, and the like of the polishing liquid.

<Surfactant>
The polishing liquid according to this embodiment can further contain a surfactant. As the surfactant, water-soluble anionic surfactants such as ammonium lauryl sulfate, polyoxyethylene lauryl ether ammonium sulfate, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate, lauroyl sarcosine salt; polyoxyethylene lauryl ether Water-soluble nonionic surfactants such as polyethylene glycol monostearate; hexadecyltrimethylammonium salt, myristyltrimethylammonium salt, lauryltrimethylammonium salt, stearyltrimethylammonium salt, cetyltrimethylammonium salt, distearyldimethylammonium salt, alkyl Water-soluble cationic surfactants such as benzyldimethylammonium salt, coconutamine acetate, stearylamine acetate, etc. And the like. Among these, as the surfactant, a water-soluble anionic surfactant is preferable. In particular, it is more preferable to use at least one water-soluble anionic surfactant such as a polymer dispersant obtained using an ammonium salt as a copolymerization component. A water-soluble nonionic surfactant, a water-soluble anionic surfactant, a water-soluble cationic surfactant and the like may be used in combination. The content of the surfactant is, for example, 0.0001 to 0.1% by mass based on the total mass of the polishing liquid.

<Water>
The polishing liquid according to the present embodiment contains water. The content of water in the polishing liquid may be the remainder of the polishing liquid excluding the content of other components.

<PH of polishing liquid>
The pH of the polishing liquid according to the present embodiment is 4 or less from the viewpoint of suppressing the corrosion of the cobalt-based metal. For example, a polishing liquid having a pH exceeding 4 and containing an oxidizing agent causes corrosion of a cobalt-based metal. Although the factor which shows such behavior is not necessarily clear, the present inventors guess as follows. It is considered that the polishing liquid having a pH exceeding 4 and containing an oxidizing agent changes cobalt to cobalt tetroxide. Since cobalt tetroxide is dissolved in an acidic or basic aqueous solution, it is considered that cobalt is dissolved by becoming cobalt tetroxide in the polishing liquid, and as a result, the cobalt is corroded.

On the other hand, in the region where the pH is 4 or less, the higher the pH is (the closer the pH is to 4), the more the corrosion of the cobalt-based metal tends to be suppressed. This is presumably because the cobalt-based metal tends to be corroded as the amount of hydrogen ions in the polishing liquid increases. That is, the lower the pH, the more hydrogen ions in the polishing liquid in the polishing liquid, and the cobalt-based metal tends to be corroded. Therefore, the pH of the polishing liquid is preferably 1 or higher, preferably 2 or higher. It is more preferable that it is 3 or more.

In addition, in order to adjust pH, well-known pH adjusters (for example, aqueous ammonia, potassium hydroxide, etc.), such as an acid and a base, can be used. The pH is defined as the pH at a liquid temperature of 25 ° C.

The pH of the polishing liquid can be measured with a pH meter (for example, model number: PHL-40, manufactured by Electrochemical Instrument Co., Ltd.). For example, after two-point calibration using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH: 6.86 (25 ° C.)) The pH of the polishing liquid can be measured by putting the electrode in the polishing liquid and measuring the value after 2 minutes or more have passed and stabilized at 25 ° C.

The constituents of the polishing liquid according to the present embodiment can be stored, transported and used in a plurality of liquids. Therefore, for example, the polishing liquid according to the present embodiment may be obtained by mixing a component containing an oxidizing agent that has been stored separately and a component other than the oxidizing agent. That is, the polishing liquid is a first liquid and a second liquid that have been stored separately (that is, the abrasive particles, a methacrylic acid polymer obtained without using an inorganic acid as a raw material during the synthesis, and The phthalic acid compound, the isophthalic acid compound and the dicarboxylic acid compound represented by the general formula (I), salts thereof, acid anhydrides of the phthalic acid compound and the dicarboxylic acid compound represented by the general formula (I) Obtained by mixing at least one carboxylic acid compound component selected from the group consisting of acid anhydrides, a first liquid containing the metal anticorrosive, and a second liquid containing the oxidizing agent). May be. The first liquid may further contain an organic solvent, a surfactant and the like.

The polishing liquid of this embodiment can be suitably used for polishing a film to be polished having a wiring forming portion having a wiring density of 50% or more. Here, the wiring density is a value calculated from the respective widths of the interlayer insulating film portion and the wiring metal portion (including the barrier metal) in the portion where the wiring is formed. For example, when the line and space is 100 μm / 100 μm, the wiring density at that portion is 50%.

When the wiring density is 50% or more, the area occupied by the wiring metal portion becomes large, and the problem of erosion and seam in the portion tends to become remarkable. However, polishing is performed using the polishing liquid of this embodiment. Thus, these problems can be reduced. The polishing liquid of this embodiment can also be suitably used for polishing a film to be polished having a wiring forming portion having a wiring density of 80% or more.

[Polishing method]
The polishing method of the present embodiment is a polishing method in which a film to be polished containing cobalt element formed on at least one surface of a substrate is polished using the above-described polishing liquid to remove an excess portion containing cobalt element. It is. Namely, a step of obtaining a solution by dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid, a step of obtaining a methacrylic acid polymer by polymerizing a monomer component containing at least methacrylic acid in the solution, and a methacrylic acid polymer A step of mixing a carboxylic acid compound, abrasive particles and a metal anticorrosive to obtain a polishing liquid, a step of preparing a substrate containing a cobalt-based metal, and a step of chemically mechanically polishing the substrate using the polishing liquid. And a polishing method in which the pH of the polishing liquid is 4 or less. More specifically, the step of chemically mechanically polishing the substrate includes the polishing described above between the film to be polished containing cobalt element formed on at least one surface of the substrate and the polishing cloth on the polishing surface plate. At least a part of the film to be polished by relatively moving the substrate and the polishing platen while supplying the liquid while pressing the surface of the substrate on the surface provided with the film to be polished against the polishing cloth This is a step of removing.

Hereinafter, a series of steps for forming a wiring layer in a semiconductor device using the substrate polishing method of this embodiment will be described with reference to FIG. However, the use of the polishing liquid of the present embodiment is not limited to the following steps. Since the polishing liquid obtained in the step of obtaining the polishing liquid is as described above, detailed description thereof is omitted here.

As shown in FIG. 2A, the substrate 10 before polishing has an insulating material 2 having a predetermined pattern of recesses on the silicon substrate 1 and the insulating material 2 along the unevenness of the surface of the insulating material 2. It has a barrier metal layer 3 to be coated and a cobalt-based metal 4 that covers the barrier metal layer 3, and a conductive material layer 5 is formed on the cobalt-based metal 4. In the present embodiment, the “base” refers to, for example, a structure in which predetermined layers are sequentially formed on a silicon substrate as described above. In particular, in the present embodiment, at least one of the formed layers includes a cobalt element. . Further, as described above, the cobalt-based metal 4 also has a role as a barrier metal layer. However, for the sake of explanation, the cobalt-based metal 4 will be described separately from the barrier metal layer 3.

Examples of the insulating material 2 include a silicon-based insulating material and an organic polymer-based insulating material. Silicon-based insulating materials include silicon dioxide; fluorosilicate glass; organosilicate glass obtained using trimethylsilane or dimethoxydimethylsilane as a starting material; silica-based insulating materials such as silicon oxynitride and silsesquioxane hydride; silicon carbide A silicon nitride may be used. Examples of the organic polymer insulating material include wholly aromatic low dielectric constant insulating materials. Among these, silicon dioxide is particularly preferable.

The insulating material 2 is formed by a CVD (chemical vapor deposition) method, a spin coating method, a dip coating method, or a spray method. Specific examples of the insulating material 2 include an insulating material in an LSI manufacturing process, particularly a multilayer wiring forming process.

The barrier metal layer 3 is formed to prevent the conductive material from diffusing into the insulating material 2 and to improve the adhesion between the insulating material 2 and the conductive material layer 5. Examples of the barrier metal used for the barrier metal layer 3 include tantalum compounds such as tantalum, tantalum nitride, and tantalum alloys, titanium compounds such as titanium, titanium nitride, and titanium alloys, tungsten compounds such as tungsten, tungsten nitride, and tungsten alloys, ruthenium, and the like. And ruthenium compounds. The barrier metal layer 3 may have a single layer structure made of one of these or a laminated structure made of two or more. The barrier metal layer 3 is formed by vapor deposition, CVD (chemical vapor deposition) or the like. Note that only the cobalt-based metal 4 may be provided as the barrier metal layer 3.

Examples of cobalt used for the cobalt-based metal 4 include cobalt, a cobalt alloy, a cobalt oxide, and a cobalt alloy oxide. The cobalt-based metal is formed by a known sputtering method or the like.

Examples of the conductive material used for the conductive material layer 5 include copper, copper alloys, copper oxides, copper-based metals such as copper alloys, tungsten metals such as tungsten and tungsten alloys, silver, Examples include noble metals such as gold. Among these, metals having copper as a main component such as copper, copper alloys, copper oxides, and copper alloy oxides are preferable. The conductive material layer 5 is formed by a known sputtering method, plating method or the like.

The thickness of each layer is not particularly limited. For example, the thickness of the insulating material 2 is about 0.01 to 2.0 μm, and the thickness of the barrier metal layer 3 is about 0.01 to 2.5 μm. The thickness of the metal 4 is preferably about 0.01 to 2.5 μm, and the thickness of the conductive material layer 5 is preferably about 0.01 to 2.5 μm.

The step of chemically mechanically polishing the cobalt-based metal 4 (substrate containing cobalt element) using the polishing liquid can include, for example, the following first polishing step and second polishing step. In the first polishing step of polishing the conductive material layer 5 from the state shown in FIG. 2A to the state shown in FIG. 2B, the conductive material layer 5 on the surface of the substrate 10 before polishing is For example, polishing is performed by CMP using a polishing liquid for a conductive material having a sufficiently high polishing rate ratio of the conductive material layer 5 / cobalt metal 4. Thereby, the board | substrate 20 which has the conductor pattern in which the cobalt-type metal 4 of the convex part on a board | substrate is exposed on the surface, and the electroconductive substance layer 5 was left in the recessed part is obtained. As the polishing liquid for the conductive material having a sufficiently high polishing rate ratio of the conductive material layer 5 / cobalt-based metal 4, for example, the polishing liquid described in Japanese Patent No. 337464 can be used. In the first polishing step, a part of the cobalt-based metal 4 in the convex portion may be polished together with the conductive material layer 5.

In the subsequent second polishing step, the conductor pattern obtained in the first polishing step is polished using the polishing liquid of this embodiment as a film to be polished for the second polishing step.

In the second polishing step, while the substrate 20 is pressed onto the polishing cloth of the polishing surface plate, the polishing surface plate and the substrate 20 are supplied while supplying the polishing liquid of the present embodiment between the polishing cloth and the substrate. The cobalt-based metal 4 exposed in the first polishing step is polished by relatively moving the.

As a polishing apparatus, a general polishing apparatus having a holder for holding a substrate to be polished and a polishing platen connected to a motor capable of changing the number of rotations and attached with a polishing cloth can be used. 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.

The polishing conditions are not particularly limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 rpm (times / min) or less so that the substrate does not pop out. The pressing pressure of the substrate having the film to be polished onto the polishing cloth is preferably 1 to 100 kPa, and 5 to 50 kPa in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern. It is more preferable.

During polishing, the polishing liquid of this embodiment is continuously supplied between the polishing cloth and the film to be polished 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 polishing liquid. The substrate after polishing is preferably washed in running water and then dried after removing water droplets adhering to the substrate using spin drying or the like.

In order to perform chemical mechanical polishing with the surface state of the polishing cloth always the same, it is preferable to perform a polishing cloth conditioning step before polishing. For example, the polishing cloth is conditioned with a liquid containing at least water using a dresser with diamond particles. Subsequently, it is preferable to perform the polishing method of the present embodiment and further add a substrate cleaning step.

In the second polishing step, at least the exposed cobalt-based metal 4 is polished to remove excess cobalt. In the second polishing step, the cobalt-based metal 4 is polished, and when the barrier metal layer 3 is exposed, the polishing is terminated, and the barrier metal layer 3 may be separately polished with a polishing liquid for barrier metal layer polishing. Further, as shown in FIGS. 2B to 2C, the cobalt metal 4 to the barrier metal layer 3 may be polished in series in the second polishing step. Furthermore, the conductive material layer 5 embedded in the recess may be polished together with the cobalt metal 4 and the barrier metal layer 3.

The insulating material 2 under the convex barrier metal layer 3 is completely exposed, the conductive material layer 5 serving as a wiring layer is left in the concave portion, and the barrier metal layer 3 and the cobalt-based metal 4 at the boundary between the convex portion and the concave portion. The polishing is finished when the substrate 30 having the desired pattern in which the cross section is exposed is obtained.

In order to ensure better flatness at the end of polishing, overpolishing may be further performed as shown in FIG. For example, when the time until a desired pattern is obtained in the second polishing step is 100 seconds, polishing for 50 seconds in addition to the polishing for 100 seconds is referred to as over polishing 50%. In the case of overpolishing, a part of the insulating material 2 is also removed by polishing.

A second-layer insulating material and metal wiring are further formed on the metal wiring thus formed, and then polished to obtain a smooth surface over the entire surface of the semiconductor substrate. By repeating this step a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

The polishing liquid of the present embodiment can be used not only for polishing a metal film formed on a semiconductor substrate as described above but also for polishing a substrate such as a magnetic head.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples without departing from the technical idea of the present invention. For example, the type and ratio of the polishing liquid material may be other than the type and ratio described in this example, and the composition and structure of the object to be polished may also be a composition and structure other than those described in this example.

<Examples and Comparative Examples>
(Synthesis of methacrylic acid polymer)
(Polymers 1-7, 9-15)
Table 1 shows the molar ratio (mol%) of each monomer in the methacrylic acid polymer, the polymerization initiator used when synthesizing the methacrylic acid polymer, and the acid for dissolving the polymerization initiator. Water containing an acid shown in Table 1 was prepared as an aqueous solvent, and a polymerization initiator was dissolved therein. Subsequently, the monomer components shown in Table 1 were polymerized in an aqueous solvent to obtain a methacrylic acid polymer (polymer 8).
AIBN was dissolved in the monomer component containing methacrylic acid (molar ratio: methacrylic acid / acrylic acid = 94/6) as a polymerization initiator (raw material A). Then, the polymer 8 was obtained by dripping the said raw material A in water. The polymerization initiator was dissolved in water.

The molecular names of the polymerization initiators in Table 1 are as follows.
VA-061: 2,2′-azobis [2- (2-imidazolin-2-yl) propane]
AIBN: 2,2′-azobis (isobutyronitrile)
VA-057: 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine]
Since VA-061 is soluble in an acidic aqueous solution, the acids shown in Table 1 are added when the polymer is synthesized.

(Polishing liquid preparation method)
According to Tables 2 to 3, a predetermined amount of the methacrylic acid polymer (polymers 1 to 15), carboxylic acid compound, abrasive particles, metal anticorrosive agent, etc. are mixed to prepare each polishing liquid of each example and each comparative example. did. Incidentally, colloidal silica having an average particle diameter of 70 nm was used as the abrasive particles. The pH was measured with a pH meter (manufactured by Electrochemical Instrument Co., Ltd., model number: PHL-40).

(Polishing copper pattern substrate)
A copper film other than the groove of the patterned substrate with copper wiring (Advanced Technology Development Facility, Inc., 854CMP pattern) is formed by a known CMP method using a polishing liquid for copper film polishing (HS-H635, manufactured by Hitachi Chemical Co., Ltd.). Polishing was performed to expose the convex barrier layer on the surface to be polished. As a result, a substrate as shown in FIG. 1B was obtained. This board | substrate was used for the grinding | polishing characteristic evaluation of the polishing liquid of each Example and a comparative example. The barrier layer of the pattern substrate was made of a tantalum nitride film having a thickness of 250 mm.

The pattern substrate was subjected to chemical mechanical polishing for 60 seconds under the following polishing conditions with each metal film polishing liquid prepared by the above polishing liquid preparation method. This corresponds to the second polishing step, and the convex interlayer insulating film was exposed on the surface to be polished in about 30 seconds except for Comparative Example 9. For the remaining 30 seconds, the exposed interlayer insulating film was polished for the protrusions.

[Substrate polishing conditions]
Polishing device: Single-sided metal film polishing machine (MIRRA, Applied Materials)
Polishing cloth: Polishing cloth made of suede foam polyurethane resin Surface plate rotation speed: 93 times / min
Head rotation speed: 87 times / min
Polishing pressure: 14 kPa
Supply amount of polishing liquid: 200 ml / min

The fact that the interlayer insulating film was exposed on the polished surface in the first 30 seconds was confirmed by measuring the resistivity of the portion where the metal wiring was not exposed on the surface using a resistivity meter.

In Comparative Example 9, the entire interlayer insulating film could not be exposed on the surface to be polished in the first 30 seconds of polishing, but the convex interlayer insulating film was exposed on the surface to be polished in the remaining 30 seconds of polishing.

Next, a sponge brush (made of polyvinyl alcohol resin) was pressed against the surface to be polished of the patterned substrate polished in the substrate polishing step, and the substrate and the sponge brush were rotated while supplying distilled water to the substrate, and washed for 60 seconds. . Next, the sponge brush was removed, and distilled water was supplied to the polished surface of the substrate for 60 seconds. Finally, the substrate was rotated at high speed to blow off distilled water and dried to obtain a pattern substrate to be used in the following evaluation.

(Flatness evaluation)
The following evaluations (1) to (3) were performed on the pattern substrate obtained in the substrate cleaning step.

(1) Amount of interlayer insulating film polishing: optical film thickness meter for the thickness of an interlayer insulating film portion of a striped pattern with a total width of 2900 μm in which wiring metal portions with a width of 100 μm and interlayer insulating film portions with a width of 100 μm are alternately arranged And determined as the amount of interlayer insulating film polishing.

(2) Erosion amount: As shown in FIG. 4A, the surface shape of a striped pattern having a total width of 2990 μm in which wiring metal portions having a width of 90 μm and interlayer insulating film portions having a width of 10 μm are alternately arranged is a stylus type Measured with a step gauge. Next, as shown in FIG. 4B, the difference between the maximum polishing amount (B) of the interlayer insulating film portion of the stripe pattern and the polishing amount (A) of the interlayer insulating film portion at the outer edge of the stripe pattern. The amount of erosion was determined as (B)-(A).

FIG. 4 is a schematic cross-sectional view of a striped pattern in which a wiring metal portion having a width of 90 μm and an interlayer insulating film portion having a width of 10 μm are alternately arranged on the patterned substrate with copper wiring, 11 is an interlayer insulating film, 13 Is the barrier metal layer, 15 is the wiring metal layer, 40 is the erosion, 50 is the state before polishing, A is the polishing amount of the interlayer insulating film portion at the outer edge of the stripe pattern, and B is the polishing amount of the interlayer insulating film portion of the stripe pattern Maximum values are shown respectively.

(3) Seam amount: As shown in FIG. 5 (a), the surface shape of a striped pattern with a total width of 2900 μm in which wiring metal portions with a width of 100 μm and interlayer insulating film portions with a width of 100 μm are alternately arranged is a stylus type Measured with a step gauge. Next, as shown in FIG. 5B, the seam amount was determined as the distance (C) from the upper end of the interlayer insulating film near the wiring metal portion to the lower end of the excessively shaved interlayer insulating film.

FIG. 5 is a schematic cross-sectional view of a portion in which the wiring metal part having a width of 100 μm and the interlayer insulating film part having a thickness of 100 μm are alternately arranged on the patterned substrate with copper wiring, 11 is an interlayer insulating film, 13 is a barrier layer, 15 is a wiring metal layer, 50 is a state before polishing, 60 is the vicinity of the wiring metal part of the interlayer insulating film part, 70 is a seam, and C is an interlayer insulating film excessively shaved from the upper end of the interlayer insulating film part near the wiring metal part Indicates the distance to the bottom of the part.

(Evaluation of etching amount for cobalt (Co-ER))
A blanket substrate (a) in which a cobalt layer having a thickness of 300 nm was formed by CVD on an 8-inch silicon substrate was prepared. The blanket substrate (a) was cut into 20 mm square chips to prepare evaluation chips (b).

The chips for evaluation (b) were placed in a beaker containing 50 g of each polishing liquid and immersed in a 60 ° C. constant temperature bath for 1 minute. The evaluation chip (b) after immersion was taken out and thoroughly washed with pure water, and then nitrogen gas was blown to dry the water on the chip. The resistance of the evaluation chip (b) after drying was measured with a resistivity meter and converted into the film thickness of the cobalt layer after immersion by the following formula (1).

A calibration curve was obtained from information on resistance values corresponding to the respective film thicknesses of the blanket substrate (a), and the film thickness of the cobalt layer was determined from the following formula (1).
Film thickness [nm] of cobalt layer after immersion = 104.5 × (resistance value [mΩ] / 1000 of evaluation chip (b)) − 0.893 (1)
And the etching rate of the cobalt layer was calculated | required from the following formula (2) from the film thickness of the obtained cobalt layer after immersion, and the film thickness of the cobalt layer before immersion.
Etching rate of cobalt layer (Co-ER) [nm / min] = (film thickness of cobalt layer before immersion [nm] −film thickness of cobalt layer after immersion [nm]) / 1 minute (2)

The above evaluation results are shown in Table 2 and Table 3.

(Evaluation of polishing rate)
The following substrates (a) to (e) were used for evaluation of the blanket substrate polishing rate.
Blanket substrate (a): A silicon substrate on which cobalt (thickness: 300 nm) is formed by a CVD method.
Blanket substrate (b): A silicon substrate on which copper (thickness: 1000 nm) is formed by a plating method.
Blanket substrate (c): A silicon substrate on which tantalum nitride (thickness: 200 nm) is formed by sputtering.
Blanket substrate (d): A silicon substrate on which silicon dioxide (thickness: 1000 nm) is formed by CVD.
Blanket substrate (e): A silicon substrate on which an organosilicate glass (thickness: 1000 nm) is formed.
Using the blanket substrates (a) to (e), chemical mechanical polishing was performed for 60 seconds under the substrate polishing conditions with the polishing liquids of Examples 1 to 15.

[Calculation of polishing speed]
The polishing rate was calculated by the following method using the blanket substrates (a) to (e) after chemical mechanical polishing.

Cobalt film: The resistance of the blanket substrate (a) before and after polishing is measured using a metal film thickness measuring device (product name “VR-120 / 08S” manufactured by Hitachi Kokusai Electric Co., Ltd.), and then the cobalt layer Similar to the calculation of the etching rate, the film thickness of the cobalt layer before and after polishing was calculated using the following equation (1).
Film thickness [nm] = 104.5 × (Cobalt layer resistance [mΩ] / 1000) −0.893 (1)
Using the film thickness before and after polishing of the cobalt layer obtained as a result of the calculation of (1), the polishing rate (Co polishing rate) [nm / min] when the cobalt film was polished was evaluated.

Copper film, tantalum nitride film: About blanket substrates (b) and (c), film thickness before and after polishing using a metal film thickness measuring device (product name “VR-120 / 08S” manufactured by Hitachi Kokusai Electric Co., Ltd.) The difference was measured, and from the obtained results, the polishing rate when polishing the copper film (Cu polishing rate) [nm / min] and the polishing rate when polishing the tantalum nitride film (TaN polishing rate) [nm / min] Evaluated.

Silicon dioxide film, organosilicate glass film: obtained by measuring the film thickness difference before and after polishing using a film thickness measuring device (manufactured by Dainippon Screen Mfg. Co., Ltd., product name “Lambda Ace, VL-M8000LS”) From the results, the polishing rate when polishing the silicon dioxide film (SiO ₂ polishing rate) [nm / min] and the polishing rate when polishing the organosilicate glass film (SiOC polishing rate) [nm / min] were evaluated.
These results are shown in Table 4.

As is apparent from Table 2, in Examples 1 to 15, the erosion and seam were effectively suppressed by containing a specific methacrylic acid polymer, a specific dicarboxylic acid and a metal anticorrosive at the same time. High flatness was obtained. It was also found that the cobalt etching rate was significantly suppressed even at 60 ° C.

On the other hand, in Comparative Examples 1 to 7 and 11 in Table 3, the erosion and seam were the same values as in the example, but the cobalt etching rate was high. Further, in Comparative Examples 8 to 9 in Table 3, erosion was greatly generated at 430 to 570 mm and seam was 260 to 340 mm, and the flatness of the polished surface was low. In Comparative Example 10 in Table 3, the polishing amount of the interlayer insulating film was not sufficient, and when the pH exceeded 5, the cobalt etching rate was high.

From Table 4, it was found that Examples 1 to 15 had good polishing rates for cobalt, copper, tantalum nitride, silicon dioxide and organosilicate glass. From this, in the polishing liquid of the present invention containing the methacrylic acid polymer and the carboxylic acid compound, erosion and seam are suppressed by using the specific methacrylic acid polymer, and the specific methacrylic acid polymer and the It is considered that the etching of cobalt is suppressed by using a specific dicarboxylic acid compound and adjusting the pH to 4 or less. That is, from the above results, according to the polishing liquid of the present invention, erosion and seam are suppressed, and when a layer containing cobalt element is polished, the layer containing cobalt element is excessively etched or a slit due to corrosion is generated. It is suggested that polishing can be effectively suppressed.

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2, 11 ... Insulating material (interlayer insulating film), 3, 13 ... Barrier metal layer (barrier layer), 4 ... Intermediate layer (cobalt metal), 5, 15 ... Conductive substance layer (wiring metal) Layer) 10, 20, 30 ... substrate, 40 ... erosion, 50 ... state before polishing, 60 ... near wiring metal part of interlayer insulating film, 70 ... seam.

Claims (15)

1. A step of dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid to obtain a solution;
   Polymerizing a monomer component containing at least methacrylic acid in the solution to obtain a methacrylic acid polymer;
   Mixing the methacrylic acid polymer, carboxylic acid compound, abrasive particles and metal anticorrosive to obtain a polishing liquid,
   The carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the following general formula (I), a salt thereof, an acid anhydride of the phthalic acid compound, and an acid anhydride of the dicarboxylic acid compound Containing at least one selected from the group consisting of:
   The manufacturing method of polishing liquid whose pH of the said polishing liquid is 4 or less.
   HOOC-R-COOH (I)
   [In the above general formula (I), R has 3 to 10 carbon atoms and contains only carbon and hydrogen as constituent elements. ]
2. The production method according to claim 1, wherein the aqueous solvent comprises water or water and an organic acid.
3. The manufacturing method according to claim 1 or 2, wherein the polishing liquid is a polishing liquid for chemical mechanical polishing a substrate containing cobalt.
4. The methacrylic acid-based polymer is at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. The production method according to item.
5. The production method according to any one of claims 1 to 4, wherein the metal anticorrosive contains a compound having a triazole skeleton.
6. 6. The production method according to claim 1, wherein in the step of obtaining the polishing liquid, an organic solvent is further mixed to obtain the polishing liquid.
7. The manufacturing method according to any one of claims 1 to 6, wherein in the step of obtaining the polishing liquid, an oxidizing agent is further mixed to obtain the polishing liquid.
8. In the step of obtaining the polishing liquid, the first liquid containing the methacrylic acid polymer, the carboxylic acid compound, the polishing particles, and the metal anticorrosive and the second liquid containing the oxidizing agent are mixed. The manufacturing method of Claim 7 which obtains the said polishing liquid.
9. A step of dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid to obtain a solution;
   Polymerizing a monomer component containing at least methacrylic acid in the solution to obtain a methacrylic acid polymer;
   Mixing the methacrylic acid polymer, carboxylic acid compound, abrasive particles and metal anticorrosive to obtain a polishing liquid;
   Preparing a substrate containing cobalt;
   Chemical mechanical polishing the substrate using the polishing liquid, and
   The carboxylic acid compound is a phthalic acid compound, an isophthalic acid compound, a dicarboxylic acid compound represented by the following general formula (I), a salt thereof, an acid anhydride of the phthalic acid compound, and an acid anhydride of the dicarboxylic acid compound Containing at least one selected from the group consisting of:
   A polishing method, wherein the polishing liquid has a pH of 4 or less.
   HOOC-R-COOH (I)
   [In the above general formula (I), R has 3 to 10 carbon atoms and contains only carbon and hydrogen as constituent elements. ]
10. The polishing method according to claim 9, wherein the aqueous solvent is water or water and an organic acid.
11. The polishing according to claim 9 or 10, wherein the methacrylic acid polymer is at least one selected from the group consisting of a homopolymer of methacrylic acid and a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid. Method.
12. The polishing method according to any one of Claims 9 to 11, wherein the metal anticorrosive contains a compound having a triazole skeleton.
13. The polishing method according to any one of claims 9 to 12, wherein in the step of obtaining the polishing liquid, an organic solvent is further mixed to obtain the polishing liquid.
14. The polishing method according to any one of claims 9 to 13, wherein in the step of obtaining the polishing liquid, an oxidizing agent is further mixed to obtain the polishing liquid.
15. In the step of obtaining the polishing liquid, the first liquid containing the methacrylic acid polymer, the carboxylic acid compound, the polishing particles, and the metal anticorrosive and the second liquid containing the oxidizing agent are mixed. The polishing method according to claim 14, wherein the polishing liquid is obtained.
    

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