JP2017157591A - CMP polishing liquid and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP polishing liquid which can hold down a rate of etching a cobalt-containing portion.SOLUTION: A CMP polishing liquid for cobalt polishing comprises: an aromatic carboxylic acid compound which the total of carboxylic acid and carboxylate groups is two; and water. The aromatic carboxylic acid compound has a structure in which another carboxylic acid group or carboxylate group is bonded at an ortho position of one carboxylic acid group or carboxylate group. The CMP polishing liquid has a pH over 4.0.SELECTED DRAWING: None

Description

  The present invention relates to a CMP polishing liquid and a polishing method.

  2. Description of the Related Art In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor large-scale integrated circuits (Large-Scale Integration; hereinafter referred to as “LSI”). A chemical mechanical polishing (hereinafter referred to as “CMP”) method is one of them. The CMP method is a technique frequently used in planarization of an insulating material part, formation of a metal plug, formation of a buried wiring, etc. in an LSI manufacturing process, particularly in a multilayer wiring forming process.

  In recent years, a so-called damascene method has been adopted for the formation of embedded wiring. In the damascene method, a conductive material is deposited on an insulating material portion in which a concave portion (for example, a groove portion) and a convex portion (for example, a raised portion) are formed on the surface in advance, and the conductive material is embedded in the concave portion. Next, the conductive material portion deposited on the convex portion (that is, the conductive material portion other than the inside of the concave portion) is removed by CMP to form a buried wiring.

  In the CMP of the conductive material portion, for example, first, a polishing pad is attached on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a CMP polishing liquid. Next, the surface on which the conductive material portion of the substrate is formed is pressed against the polishing pad, and a predetermined pressure (hereinafter referred to as “polishing pressure”) is applied from the back surface of the substrate. Thereafter, the polishing surface plate is rotated in this state, and the conductive material portion on the convex portion is removed by mechanical friction between the CMP polishing liquid and the conductive material portion.

  On the other hand, as shown in FIG. 3A, a liner portion 2 is usually formed between the insulating material portion 1 having irregularities and the conductive material portion 3 provided on the insulating material portion 1. Is done. The purpose of providing the liner portion 2 is to prevent the conductive material of the conductive material portion 3 from diffusing into the insulating material portion 1 and to improve the adhesion between the insulating material portion 1 and the conductive material portion 3. Etc. The liner portion 2 is formed of a barrier metal (hereinafter sometimes referred to as “barrier metal”). Since the barrier metal is a conductor, it is necessary to remove the barrier metal in the same manner as the conductive material except for the concave portion (that is, the wiring portion) in which the conductive material is embedded.

  These removals include a “first polishing step” in which the conductive material portion 3 is polished from the state shown in FIG. 3A to the state shown in FIG. 3B, and the state shown in FIG. A two-stage polishing method in which the liner part 2 and the conductive substance part 3 are polished from the state shown in FIG. 3C to the state shown in FIG. 3C, and polishing is performed with different CMP polishing liquids. Is generally applied.

  At present, copper-based metals such as copper, copper alloys, copper oxides, copper alloy oxides and the like are mainly used as materials (wiring materials) constituting the conductive material portion 3.

  The polishing liquid used for CMP of a copper-based metal contains abrasive grains, an oxidizing agent, a metal anticorrosive, and the like as necessary. Examples of the polishing liquid used for CMP of copper-based metal include those described in Patent Documents 1 and 2.

Special table 2010-538457 gazette Special table 2009-514219 gazette

  By the way, with the miniaturization of design rules, the thickness of each of the above-mentioned parts tends to be reduced. However, when the liner part 2 becomes thin, the effect of preventing the diffusion of the conductive substance and the adhesion between the insulating material part 1 and the conductive substance part 3 tend to decrease. Furthermore, since the wiring width becomes narrow, it becomes difficult to embed the conductive material in the recess (that is, the embedding property is lowered), and voids called voids tend to be easily generated in the conductive material portion 3. .

  In order to meet the requirements for miniaturization of the design rule, for example, it is conceivable to use cobalt (Co) as a material constituting the barrier metal or the conductive material part 3 forming the liner part 2.

  However, when the conventional polishing liquid is used for polishing a metal part containing cobalt (hereinafter, also referred to as “cobalt-containing part”), the cobalt-containing part may be excessively etched.

  This invention is made | formed in view of the said situation, and it aims at providing the polishing method using the CMP polishing liquid which can suppress the etching rate of a cobalt containing part, and the said CMP polishing liquid.

  The present inventors include an aromatic carboxylic acid compound having a total of 2 carboxylic acid groups and carboxylic acid groups, and water, and the aromatic carboxylic acid compound is one carboxylic acid group or carboxylic acid group. The present inventors have found that the etching rate of the cobalt-containing part can be suppressed by a polishing liquid having a structure in which another carboxylic acid group or carboxylate group is bonded to the ortho-position of and having a pH exceeding 4.0.

  The present invention includes an aromatic carboxylic acid compound having a total of 2 carboxylic acid groups and carboxylic acid groups, and water, wherein the aromatic carboxylic acid compound is an ortho of one carboxylic acid group or carboxylic acid group. Provided is a CMP polishing liquid for cobalt polishing, which has a structure in which another carboxylic acid group or a carboxylic acid group is bonded to the position, and has a pH exceeding 4.0.

The aromatic carboxylic acid compound may have a carboxylic acid group or a carboxylic acid group at each of the 1-position and the 2-position of the aromatic ring and an alkyl group at the 4-position of the aromatic ring.
The alkyl group may have 1 to 3 carbon atoms.
The aromatic carboxylic acid compound may be 4-methylphthalic acid or a salt thereof.
The CMP polishing liquid may further contain abrasive grains.
The CMP polishing liquid may further contain an organic acid component other than the aromatic carboxylic acid compound.
The CMP polishing liquid may further contain a metal oxidizing agent.
The CMP polishing liquid may further contain a metal anticorrosive.
The CMP polishing liquid may further contain an organic solvent.

  The present invention also provides a polishing method for polishing a surface to be polished containing cobalt using the CMP polishing liquid.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing method using the CMP polishing liquid which can suppress the etching rate of a cobalt containing part, and the said CMP polishing liquid can be provided.

It is a cross-sectional schematic diagram which shows the grinding | polishing method which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the grinding | polishing method which concerns on other embodiment of this invention. It is a cross-sectional schematic diagram which shows the formation process of the embedded wiring by the conventional damascene method.

In the present specification, the “polishing rate” means a rate at which the substance A to be CMP is removed by polishing (for example, a reduction amount of the thickness of the substance A per time (Removal Rate)).
“Etching rate” means the rate at which the substance A to be polished dissolves in the polishing liquid (for example, the reduction amount of the thickness of the substance A per hour (Eching rate)).
“Process” is not only an independent process, but even if it cannot be clearly distinguished from other processes, it cannot be clearly distinguished from other processes as long as the operations specified in the “process” are performed. A process is also included.
The 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.
The content of each component in the CMP polishing liquid means the total amount of the plurality of substances present in the CMP polishing liquid unless there is a specific notice when there are a plurality of substances corresponding to each component in the CMP polishing liquid. To do.
“Cobalt-containing part” means a part containing a cobalt atom, and “cobalt-containing part” includes, for example, a part containing cobalt, a cobalt alloy, a cobalt oxide, a cobalt alloy oxide, or the like. .
The “copper-containing part” means a part containing a copper atom, and the “copper-containing part” includes, for example, a part containing copper, a copper alloy, a copper oxide, a copper alloy oxide, or the like. .

  Hereinafter, embodiments of the present invention will be described in detail.

<CMP polishing liquid>
The CMP polishing liquid of this embodiment is a CMP polishing liquid for cobalt polishing. The CMP polishing liquid can be used, for example, for polishing a cobalt-containing portion. The CMP polishing liquid of this embodiment contains an aromatic carboxylic acid compound having a total of 2 carboxylic acid groups (hereinafter sometimes referred to as “carboxy groups”) and carboxylic acid groups, and water, and the fragrances described above. A group carboxylic acid compound has a structure in which another carboxylic acid group or carboxylate group is bonded to the ortho position of one carboxylic acid group or carboxylate group, and the pH is higher than 4.0. According to such a CMP polishing liquid, the etching rate of the cobalt-containing portion can be suppressed. Moreover, according to the CMP polishing liquid of the present embodiment, the etching rate can be suppressed while the polishing rate of the cobalt-containing portion is kept in a favorable range.

  The present inventors presume the reason why the CMP polishing liquid of the present embodiment has the above effect as follows. For example, the aromatic carboxylic acid compound according to the present embodiment easily forms a complex with cobalt, and as a result, a reaction layer suitable for removing the cobalt-containing portion and a protective film for preventing etching are provided. It is thought that it can be formed at the same time. Moreover, when the pH of CMP polishing liquid exceeds 4.0, it is thought that the said aromatic carboxylic acid compound is easy to coordinate to cobalt. Therefore, it is considered that the polishing rate of the cobalt-containing portion is maintained in a favorable range and the etching rate is suppressed.

  Further, according to the CMP polishing liquid of the present embodiment, for example, even when cobalt is used as a material constituting the barrier metal or the conductive material part 3 forming the liner part 2, the dissolution and corrosion of cobalt can be reduced. Therefore, defects in the wiring pattern due to dissolution and corrosion can be reduced. Therefore, it becomes easy to apply cobalt as a material constituting the barrier metal or the conductive material part 3 forming the liner part 2. Cobalt is considered to have better embedding properties than copper-based metals, so by using the above CMP polishing liquid, for example, for miniaturization of design rules (for example, 1X nm node) in the semiconductor device manufacturing process However, it is thought that it can respond.

<Abrasive>
The CMP polishing liquid of this embodiment may further contain abrasive grains (polishing particles). When the CMP polishing liquid contains abrasive grains, the polishing rate of the metal-containing part (for example, the metal-containing part provided in the vicinity of the cobalt-containing part) tends to be further improved. An abrasive grain can be used individually by 1 type or in mixture of 2 or more types.

  Examples of the constituent material of the abrasive grains include inorganic substances such as silica, alumina, zirconia, ceria, titania, germania, and silicon carbide; organic substances such as polystyrene, polyacrylic acid, and polyvinyl chloride; and modified products thereof.

  The constituent material of the abrasive is preferably at least one selected from the group consisting of silica, alumina, zirconia, ceria, titania, germania, and modified products thereof. Examples of the modified product include those obtained by modifying the surface of abrasive grains containing silica, alumina, ceria, titania, zirconia, germania, etc. with an alkyl group.

  As a constituent material of the abrasive grains, silica (silica particles, etc.) from the viewpoint of good dispersion stability in the CMP polishing liquid and a small number of polishing scratches (sometimes referred to as “scratch”) generated by CMP. And at least one selected from the group consisting of alumina (alumina particles and the like), at least one selected from the group consisting of colloidal silica and colloidal alumina is more preferable, and colloidal silica is still more preferable.

  The average particle diameter of the abrasive grains is preferably 10 nm or more, more preferably 15 nm or more, and still more preferably 20 nm or more from the viewpoint of obtaining a better polishing rate of the metal-containing portion. The average particle size of the abrasive grains is preferably 90 nm or less, more preferably 80 nm or less, and even more preferably 75 nm or less from the viewpoint of suppressing polishing scratches while maintaining good dispersion stability. In this specification, the average particle diameter of an abrasive grain means an average secondary particle diameter.

The particle size of the abrasive grains is determined by, for example, a light diffraction scattering type particle size distribution meter (for example, “COULTER N4SD” manufactured by COULTER Electronics) using a water dispersion obtained by appropriately diluting a CMP polishing liquid containing abrasive grains with water. It can be measured. For example, the measurement conditions of the light diffraction / scattering particle size distribution meter are: measurement temperature 20 ° C., solvent refractive index 1.333 (corresponding to the refractive index of water), particle refractive index Unknown (setting), solvent viscosity 1.005 mPa (water Equivalent to viscosity), Run Time 200 sec, laser incident angle 90 °. Also, for example, when the intensity is higher than 4 × 10 ⁵ so that the intensity (scattering intensity, corresponding to turbidity) falls within the range of 5 × 10 ⁴ to 4 × 10 ⁵ , the CMP polishing liquid is diluted with water. Then, an aqueous dispersion is obtained and then measured.

  When the CMP polishing liquid contains abrasive grains, the content thereof is preferably 0.05% by mass or more, more preferably in the total mass of the CMP polishing liquid, from the viewpoint of obtaining a better polishing rate of the metal-containing portion. It is 0.1 mass% or more, More preferably, it is 0.7 mass% or more. The content of the abrasive grains is preferably 5.0% by mass or less, more preferably less than or equal to 5.0% by mass in the total mass of the CMP polishing liquid, from the viewpoint of maintaining good dispersion stability of the abrasive grains and suppressing the generation of polishing flaws. It is 4.0 mass% or less, More preferably, it is 3.0 mass% or less.

<Aromatic carboxylic acid compound>
The CMP polishing liquid of this embodiment contains an aromatic carboxylic acid compound in which the total of carboxylic acid groups and carboxylic acid groups is 2. The aromatic carboxylic acid compound has a structure in which another carboxylic acid group or carboxylate group is bonded to the ortho position of one carboxylic acid group or carboxylate group. In addition, the carboxylic acid group and carboxylate group that the aromatic carboxylic acid compound may have are bonded to the aromatic ring. Such an aromatic carboxylic acid compound is presumed to function as a complexing agent for the cobalt-containing part. Examples of the carboxylate salt include potassium and ammonium. The said aromatic carboxylic acid compound can be used individually by 1 type or in mixture of 2 or more types.

  The aromatic carboxylic acid compound according to this embodiment may have one aromatic ring or may have a plurality of aromatic rings. For example, the aromatic carboxylic acid compound may have a monocyclic aromatic hydrocarbon skeleton, or may have a polycyclic aromatic hydrocarbon skeleton. The aromatic carboxylic acid compound may have a carboxylic acid group or a carboxylic acid group at each of the 1-position and the 2-position of the aromatic ring and an alkyl group at the 4-position of the aromatic ring. As said alkyl group, a C1-C3 alkyl group is mentioned, for example. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

  Specific examples of the aromatic carboxylic acid compound according to this embodiment include a compound represented by the following general formula (I).

In formula (I), R ¹ each independently represents a carboxylic acid group or a carboxylic acid group, R ² represents a monovalent substituent (excluding a carboxylic acid group and a carboxylic acid group), and n is 0 to 4 Indicates an integer. When n is 2 or more, a plurality of R ² may be the same or different.

Examples of the monovalent substituent as R ² include an alkyl group, an amino group, and a nitro group. As said alkyl group, a C1-C3 alkyl group is mentioned, for example. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. From the viewpoint of obtaining an appropriate polishing rate, n may be 0 or 1.

  Specific examples of the aromatic carboxylic acid compound include alkylphthalic acid such as phthalic acid, 3-methylphthalic acid, 4-methylphthalic acid and 4-ethylphthalic acid; aminophthalic acid such as 3-aminophthalic acid and 4-aminophthalic acid; Nitrophthalic acid such as nitrophthalic acid and 4-nitrophthalic acid; and salts thereof. Examples of the salt include potassium and ammonium.

  Specific examples of the compound represented by the formula (I) include a compound represented by the following general formula (II).

In formula (II), R ¹ and R ² are as defined above. From the viewpoint of obtaining an appropriate polishing rate, R ² is preferably a nitro group or an alkyl group, and more preferably an alkyl group. From the viewpoint of excellent solubility in the polishing liquid, the alkyl group is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

  Among these, the aromatic carboxylic acid compound is preferably phthalic acid (4-alkylphthalic acid) having an alkyl group as a substituent at the 4-position or a salt thereof. The aromatic carboxylic acid compound is more preferably phthalic acid or a salt thereof having an alkyl group having 1 to 3 carbon atoms as a substituent at the 4-position from the viewpoint of excellent solubility in the polishing liquid. More preferably, it is an acid or a salt thereof.

  The content of the aromatic carboxylic acid compound is preferably 0.0005% by mass or more, more preferably 0.001 in the total mass of the CMP polishing liquid, from the viewpoint of keeping the polishing rate of the cobalt-containing part in a better range. It is at least mass%, more preferably at least 0.0015 mass%. From the viewpoint of further suppressing the corrosion of the cobalt-containing part, the content of the aromatic carboxylic acid compound is preferably 0.009% by mass or less, more preferably 0.0085% by mass or less, in the total mass of the CMP polishing liquid. More preferably, it is 0.008 mass% or less.

<Organic acid component>
The CMP polishing liquid of this embodiment may contain an organic acid component other than the aromatic carboxylic acid compound. The organic acid component has an effect of further improving the polishing rate of the cobalt-containing part and the metal-containing part. Examples of the organic acid component include organic acids, and salts, anhydrides, and esterified products of the organic acids. An organic acid component can be used individually by 1 type or in mixture of 2 or more types.

  The organic acid may have at least one carboxy group, for example.

  Specific examples of the organic acid include carboxylic acids other than the aromatic carboxylic acid compounds, amino acids, and derivatives thereof.

  Specific examples of the carboxylic acid as the organic acid include saturated fatty acid, unsaturated carboxylic acid, hydroxy acid, aromatic carboxylic acid, and dicarboxylic acid.

  Examples of the carboxylic acid as the organic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, salicylic acid, o-toluic acid, m-toluic acid, p-toluic acid, glycolic acid, diglycolic acid, mandel Examples include acids, quinaldic acid, quinolinic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, gluconic acid, adipic acid, pimelic acid, maleic acid, fumaric acid, malic acid, tartaric acid, and citric acid.

  From the viewpoint of further suppressing the etching rate, the carboxylic acid as the organic acid is preferably a monocarboxylic acid having a hydrophobic group, and more preferably a monocarboxylic acid having a hydrophobic group and an aromatic ring.

  As amino acids, glycine, α-alanine, β-alanine, 2-aminobutyric acid, norvaline, valine, leucine, ylleucine, isoleucine, alloisoleucine, phenylalanine, proline, sarcosine, ornithine, lysine, serine, threonine, blast furnace threonine , Homoserine, tyrosine, 3,5-jordotyrosine, β- (3,4-dihydroxyphenyl) -alanine, thyroxine, 4-hydroxy-proline, cysteine, methionine, ethionine, lanthionine, cystathionine, cystine, cysteic acid, asparagine Acid, glutamic acid, S- (carboxymethyl) -cysteine, 4-aminobutyric acid, asparagine, glutamine, azaserine, arginine, canavanine, citrulline, δ-hydroxylysine, creatine, quinu Nin, histidine, 1-methylcyclohexyl-histidine, 3-methylcyclohexyl-histidine, ergothioneine, tryptophan, etc. anthranilic acid.

  When the CMP polishing liquid contains an organic acid component, the content is preferably 0.0001% by mass or more in the total mass of the CMP polishing liquid from the viewpoint of keeping the polishing rate of the cobalt-containing part in a more favorable range. 0.0005 mass% or more is more preferable, and 0.001 mass% or more is still more preferable. From the viewpoint of further suppressing the etching rate, the content of the organic acid component is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 3% by mass or less in the total mass of the CMP polishing liquid.

<Metal anticorrosive>
The CMP polishing liquid of this embodiment may contain a metal anticorrosive. When the CMP polishing liquid contains a metal anticorrosive, corrosion can be effectively suppressed while maintaining a good polishing rate for the cobalt-containing portion. A metal anticorrosive can be used individually by 1 type or in mixture of 2 or more types.

  The metal anticorrosive is preferably at least one selected from the group consisting of pyridines and azoles from the viewpoint of further suppressing corrosion of the cobalt-containing part while maintaining a good polishing rate for the cobalt-containing part. “Pyridines” refers to compounds having a pyridine skeleton in the molecule, and examples thereof include pyridine and pyridine having a substituent. The “azoles” refer to compounds having an azole skeleton in the molecule, and examples thereof include azoles and azoles having a substituent. Compounds having a pyridine skeleton and an azole skeleton are classified as “azoles”. In addition, the metal anticorrosive having an acid group in the molecule is classified as “metal anticorrosive” instead of the “organic acid component” described above.

  Examples of pyridines include 1H-1,2,3-triazolo [4,5-b] pyridine, 1-acetyl-1H-1,2,3-triazolo [4,5-b] pyridine, 3-aminopyridine, 3-hydroxypyridine, 4-hydroxypyridine, 2-acetamidopyridine, 4-pyrrolidinopyridine, 2-cyanopyridine, 3-cyanopyridine, 3,4-dihydro-3-hydroxy-4-oxo-1,2,3 -A benzotriazine, 4-aminopyridine, etc. are mentioned.

  As azoles, pyrazole, 1-allyl-3,5-dimethylpyrazole, 3,5-di (2-pyridyl) pyrazole, 3,5-diisopropylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3 , 5-dimethyl-1-phenylpyrazole, 3,5-dimethylpyrazole, 3-amino-5-hydroxypyrazole, 4-methylpyrazole, N-methylpyrazole, 3-aminopyrazole, 3-amino-5-methylpyrazole, etc. Pyrazoles of: imidazole, 1,1′-carbonylbis-1H-imidazole, 1,1′-oxalyldiimidazole, 1,2,4,5-tetramethylimidazole, 1,2-dimethyl-5-nitroimidazole, 1,2-dimethylimidazole, 1- (3-aminopropyl) imidazole Imidazoles such as 1-butylimidazole, 1-ethylimidazole, 1-methylimidazole; thiazoles such as 2,4-dimethylthiazole; benzothiazoles such as 2-mercaptobenzothiazole; tetrazole, 5-methyltetrazole, 5- Tetrazoles such as aminotetrazole and 1,5-pentamethylenetetrazole 1- (2-dimethylaminoethyl) -5-mercaptotetrazole; 1,2,3-triazole, 1,2,4-triazole, 3-amino-1 Triazoles such as 1,2,4-triazole; benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxy Benzotriazole, 5-methylbenzotriazole, the 5-Kishiru 1H- benzotriazole, benzotriazole such as 1-hydroxy -1H- benzotriazole.

  From the viewpoint of effectively suppressing corrosion while maintaining a good range of polishing rate with respect to the cobalt-containing part, metal anticorrosives are, for example, pyridines, pyrazoles, imidazoles, benzothiazoles, thiazoles, and tetrazole. It may be at least one selected from the group consisting of groups, and may be at least one selected from the group consisting of triazoles and benzotriazoles. The metal anticorrosive may be, for example, at least one selected from the group consisting of pyridines, tetrazoles, triazoles, and benzotriazoles, and at least selected from the group consisting of pyridines and benzotriazoles. It may be a kind.

  When the CMP polishing liquid contains a metal anticorrosive, the content of the anticorrosive is preferably 0.005% by mass or more in the total mass of the CMP polishing liquid from the viewpoint of further suppressing the etching rate, and 0.01% by mass. % Or more is more preferable, and 0.02 mass% or more is still more preferable. The content of the metal anticorrosive is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, based on the total mass of the CMP polishing liquid, from the viewpoint of securing the polishing rate. More preferably, it is 1% by mass or less.

<Metal oxidizing agent>
The CMP polishing liquid of this embodiment may contain a metal oxidant. The metal oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, and ozone. The metal oxidizing agent may be hydrogen peroxide, for example, from the viewpoint of improving the polishing rate of the metal-containing portion. A metal oxidizing agent can be used individually by 1 type or in mixture of 2 or more types.

  When the CMP polishing liquid contains a metal oxidizer, the content is preferably 0.01% by mass or more in the total mass of the CMP polishing liquid from the viewpoint of obtaining a better polishing rate of the cobalt-containing part. 02 mass% or more is more preferable, and 0.05 mass% or more is still more preferable. The content of the metal oxidizer is preferably 30% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less in the total mass of the CMP polishing liquid from the viewpoint of preventing the surface to be polished from being rough.

<Organic solvent>
The CMP polishing liquid of the present embodiment may contain an organic solvent (excluding the aromatic carboxylic acid compound and the compound corresponding to the organic acid component). When the CMP polishing liquid contains an organic solvent, the wettability of the CMP polishing liquid with respect to a metal-containing part (for example, a metal-containing part provided in the vicinity of the cobalt-containing part) can be improved. Although there is no restriction | limiting in particular as an organic solvent, What can mix with water is preferable and what melt | dissolves 0.1g or more with respect to 100g of water at 25 degreeC is more preferable. An organic solvent can be used individually by 1 type or in mixture of 2 or more types.

  Examples of the organic solvent include carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as butyl lactone and propyl lactone; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, Glycols such as triethylene glycol and tripropylene glycol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (excluding glycol derivatives) ); Methanol, ethanol, propanol, Alcohols such as butanol, n-pentanol, n-hexanol, isopropanol, 3-methoxy-3-methyl-1-butanol and 1,3-butanediol; ketones such as acetone and methyl ethyl ketone; dimethylformamide, n- Amides such as methyl-2-pyrrolidone; esters such as ethyl acetate and ethyl lactate (excluding carbonic acid esters and lactones); and sulfolanes such as sulfolane.

  The organic solvent may be a derivative of glycols. Examples of glycol derivatives include 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 Glycol monoethers such as monopropyl ether, 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, diethyl 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 Examples include glycol ethers such as dipropyl ether, 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. Et It is.

  The organic solvent is preferably at least one selected from the group consisting of glycols, derivatives of glycols, alcohols, and carbonates.

  When the CMP polishing liquid contains an organic solvent, the content is preferably 0.01% by mass or more in the total mass of the CMP polishing liquid from the viewpoint of obtaining good wettability with respect to the metal-containing portion. 05 mass% or more is more preferable, and 0.1 mass% or more is still more preferable. In addition, the content of the organic solvent is preferably 50% by mass or less, more preferably 10% by mass or less, based on the total mass of the CMP polishing liquid, from the viewpoint of preventing the possibility of ignition and performing the manufacturing process safely. 5 mass% or less is still more preferable.

<Other optional components>
The CMP polishing liquid of the present embodiment can contain an optional component other than the above-mentioned components in consideration of the obtained effect and the like. Examples of optional components include additives such as dispersants, surfactants, and water-soluble polymers used in general metal polishing liquids.

<Water>
The CMP polishing liquid contains water. Water is not particularly limited, but pure water can be preferably used. Water may be blended as the remainder, and the content is not particularly limited.

<PH of CMP polishing liquid>
The pH of the CMP polishing liquid of this embodiment exceeds 4.0. The pH of the CMP polishing liquid is preferably 4.5 or more, more preferably 5.0 or more, and further preferably 5.5 or more from the viewpoint of further suppressing the etching of the cobalt-containing portion. preferable. The pH of the CMP polishing liquid is preferably 10.5 or less, more preferably 9.5 or less, and preferably 8.0 or less from the viewpoint of keeping the polishing rate of the cobalt-containing part in a better range. More preferably it is.

  The pH can be adjusted by, for example, the amount of acid component added. The pH can also be adjusted by adding an alkaline component including, for example, ammonia, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide (TMAH) and the like.

  The pH of the CMP polishing liquid can be measured with a pH meter (for example, “pHMeter F-51” manufactured by Horiba, Ltd.). After three-point calibration using standard buffer (phthalate pH buffer pH: 4.01, neutral phosphate pH buffer pH: 6.86, borate pH buffer pH: 9.18) Then, the value is measured after the electrode is put in a CMP polishing liquid and stabilized for 3 minutes or more. At this time, both the standard buffer solution and the CMP polishing solution are set to 25 ° C.

<Polishing liquid set>
The CMP polishing liquid of this embodiment is stored as a multi-liquid type polishing liquid set in which the constituents of the polishing liquid are divided into a plurality of additive liquids so that a plurality of additive liquids are mixed to form the polishing liquid. Also good. When the CMP polishing liquid of this embodiment contains abrasive grains, the constituents of the polishing liquid are added to the slurry and the additive liquid so that, for example, the slurry and the additive liquid are mixed to become the polishing liquid. And may be stored as a multiple liquid type (for example, two liquid type) polishing liquid set. The polishing liquid set may be divided into, for example, a slurry containing abrasive grains and water, and an additive liquid containing an aromatic carboxylic acid compound according to the present embodiment and, if necessary, a metal oxidizing agent.

  When the component of the polishing liquid contains a component that is easily decomposed (for example, hydrogen peroxide as a metal oxidizing agent), it is preferably stored as a multi-liquid type polishing liquid set. In this case, the polishing liquid set is preferably in a form divided into, for example, a slurry containing abrasive grains, the aromatic carboxylic acid compound according to the present embodiment, and water, and an additive liquid containing a component that easily decomposes and water. .

  The CMP polishing liquid and the polishing set of the present embodiment can be stored in the state of a concentrated storage liquid that is used after being diluted with a liquid medium such as water. Here, the concentration means that the content ratio of each component before dilution with the liquid medium is higher than the content ratio in the CMP polishing liquid, and is not limited to the one that has undergone the concentration step.

  The CMP polishing liquid of this embodiment can be applied to the formation of a wiring pattern in a semiconductor device, for example.

<Polishing method>
The polishing method of this embodiment is a polishing method for polishing a surface to be polished containing cobalt using the CMP polishing liquid of this embodiment described above. The surface to be polished containing cobalt is, for example, a cobalt-containing portion. When the CMP polishing liquid of this embodiment is used for polishing a surface to be polished containing cobalt, the surface to be polished containing cobalt can be polished at a good polishing rate, and etching of cobalt can be suppressed. The surface to be polished may have a metal-containing portion made of a metal other than cobalt. That is, the polishing method of the present embodiment may be a method of polishing a surface to be polished having a cobalt-containing portion and a metal-containing portion made of a metal other than cobalt using the CMP polishing liquid of the present embodiment. The polishing method of the present embodiment uses the CMP polishing liquid of the present embodiment to have a cobalt-containing portion on the surface to be polished having a cobalt-containing portion and not having a copper-containing portion containing copper as a main component. A polishing method in which at least a part is polished and removed may be used. Moreover, the to-be-polished surface may contain the insulating material part mentioned later.

  Specific examples of the polishing method of this embodiment include a polishing method in which at least a part of the cobalt-containing portion of the surface to be polished having at least the cobalt-containing portion is polished and removed using the CMP polishing liquid of this embodiment. . The polishing method of the present embodiment is, for example, in a state where the polishing surface is pressed against the polishing pad while supplying the CMP polishing liquid of the present embodiment between the polishing surface and the polishing pad on the polishing surface plate. A polishing method in which at least a part of the cobalt-containing portion is polished and removed by relatively moving the surface to be polished and the polishing surface plate may be used.

  The polishing method of this embodiment can be applied to a series of steps for forming a wiring layer in a semiconductor device. In this case, the polishing method of the present embodiment includes, for example, an insulating material part having irregularities (concave and convex parts) on the surface, a liner part that covers the insulating material part along the irregularities, and the concave and convex parts. A step of preparing a substrate having a conductive material portion that fills and coats the liner portion, a first polishing step of polishing the conductive material portion to expose the liner portion on the convex and concave portions of the unevenness, And a second polishing step of polishing and removing the liner portion exposed in the first polishing step. Here, when the conductive material portion contains cobalt, the CMP polishing liquid of the present embodiment may be used in the first polishing step. When the liner portion contains cobalt, In the polishing step, the CMP polishing liquid of this embodiment may be used. The liner part may be composed of a plurality of layers, for example.

  Hereinafter, an example of the polishing method will be described with reference to FIGS. However, the use of the polishing method is not limited to the following steps. FIG. 1 is a schematic cross-sectional view showing a polishing method according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing a polishing method according to the second embodiment.

  A substrate 10 a shown in FIG. 1 includes an insulating material part 11, a liner part 12, and a conductive substance part 13. As shown in FIG. 1A, a substrate 10a before polishing is formed on a silicon substrate (not shown) along an insulating material part 11 having irregularities of a predetermined pattern and irregularities on the surface of the insulating material part 11. And a liner portion 12 that covers the insulating material portion 11 and a conductive substance portion 13 formed on the liner portion 12.

  The substrate 20a shown in FIG. 2 includes an insulating material portion 21, a first liner portion 22b and a second liner portion 22a as the liner portion 22, and a conductive substance portion 23. As shown in FIG. 2A, the unpolished substrate 20 a is provided on a silicon substrate (not shown) along an insulating material part 21 having irregularities with a predetermined pattern and irregularities on the surface of the insulating material part 21. A first liner portion 22b for covering the insulating material portion 21, a second liner portion 22a for covering the first liner portion 22b, and a conductive substance portion 23 formed on the second liner portion 22a, Have

  Examples of the material forming the insulating material portions 11 and 21 include a silicon-based insulating material (insulator), an organic polymer-based insulating material (insulator), and the like. Silicon-based insulating materials include silica-based insulating materials such as organosilicate glass, silicon oxynitride and silsesquioxane hydride obtained from silicon dioxide, fluorosilicate glass, trimethylsilane, and dimethoxydimethylsilane as starting materials; silicon carbide A silicon nitride may be used. Examples of the organic polymer insulating material include wholly aromatic low dielectric constant insulating materials (insulators). Among these, silicon dioxide is particularly preferable.

  The insulating material portions 11 and 21 are formed by, for example, a CVD (chemical vapor deposition) method, a spin coating method, a dip coating method, a spray method, or the like. Specific examples of the insulating material portions 11 and 21 include an interlayer insulating film in an LSI manufacturing process (particularly, a multilayer wiring forming process).

  The liner portions 12 and 22 prevent the conductive material from diffusing into the insulating material portions 11 and 21, and improve the adhesion between the insulating material portions 11 and 21 and the conductive material portions 13 and 23. It is formed.

  Examples of materials that can be used to form the liner portion 12, the first liner portion 22b, and the second liner portion 22a include cobalt compounds such as cobalt, cobalt alloys, cobalt oxides, cobalt alloy oxides, and tantalum. Tantalum compounds such as 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 compounds such as ruthenium, ruthenium nitride, and ruthenium alloys. . The material constituting the liner portion 12, the first liner portion 22b, and the second liner portion 22a is, for example, the purpose of use of the liner portion 12, the first liner portion 22b, and the second liner portion 22a, and conductivity. In consideration of the material of the substance parts 13 and 23, it can determine suitably based on the knowledge of those skilled in the art. For example, at least one selected from the group consisting of the tantalum compound, the titanium compound, the tungsten compound, and the ruthenium compound is used to form the second liner portion 22a, and to form the first liner portion 22b. One embodiment may be used. The liner portion 12, the first liner portion 22b, and the second liner portion 22a are formed by, for example, vapor deposition, CVD (chemical vapor deposition), sputtering, or the like.

  The conductive material portions 13 and 23 mainly include cobalt compounds such as cobalt, cobalt alloy, cobalt oxide, and cobalt alloy oxide; copper such as copper, copper alloy, copper oxide, and copper alloy oxide. Metals as components; Metals mainly composed of tungsten such as tungsten and tungsten alloys; Noble metals such as silver and gold can be used. The conductive material portions 13 and 23 are formed by, for example, a known sputtering method, CVD (chemical vapor deposition), plating method or the like.

  In the substrate 10a used in the polishing method of the present embodiment, at least one selected from the group consisting of the liner portion 12 and the conductive material portion 13 is a cobalt-containing portion. For example, the conductive material portion 13 is made of a cobalt compound such as cobalt, a cobalt alloy, a cobalt oxide, or a cobalt alloy oxide, and the liner portion 12 is made of a tantalum compound such as tantalum, tantalum nitride, or a tantalum alloy, titanium, A form using a titanium compound such as titanium nitride or a titanium alloy, a tungsten compound such as tungsten, tungsten nitride, or a tungsten alloy, or a ruthenium compound such as ruthenium, ruthenium nitride, or a ruthenium alloy may be used. In addition, for example, the conductive material portion 13 may be made of copper, a copper alloy, a copper oxide, a copper-based metal such as a copper alloy oxide, a tungsten, a tungsten-based metal such as a tungsten alloy, A form in which a noble metal such as silver or gold is used and a cobalt compound such as cobalt, a cobalt alloy, a cobalt oxide, or a cobalt alloy oxide is used for the liner portion 12 may be used.

  In the substrate 20a used in the polishing method of this embodiment, at least one selected from the group consisting of the first liner portion 22b, the second liner portion 22a, and the conductive material portion 23 is a cobalt-containing portion. For example, a cobalt compound such as cobalt, a cobalt alloy, a cobalt oxide, or a cobalt alloy oxide is used for the conductive material portion 23, and tantalum or tantalum nitride is used for the first liner portion 22b and the second liner portion 22a. Tantalum compounds such as tantalum alloys, titanium compounds such as titanium, titanium nitride and titanium alloys, tungsten compounds such as tungsten, tungsten nitride and tungsten alloys, ruthenium compounds such as ruthenium, ruthenium nitride and ruthenium alloys, etc. Also good. In addition, for example, in the conductive material portion 23, copper, a copper alloy, a copper oxide, a copper-based metal such as a copper alloy oxide, a tungsten, a tungsten-based metal such as a tungsten alloy, Using a noble metal such as silver or gold, the first liner portion 22b has a tantalum compound such as tantalum, tantalum nitride, or a tantalum alloy, a titanium compound such as titanium, titanium nitride, or a titanium alloy, tungsten, tungsten nitride, tungsten alloy, or the like. In the form using a cobalt compound such as cobalt, a cobalt alloy, a cobalt oxide, a cobalt alloy oxide, or the like in the second liner portion 22a using a tungsten compound, ruthenium, ruthenium nitride, a ruthenium alloy, or the like. There may be.

  The thickness of the insulating material portions 11 and 21 is preferably about 0.01 μm to 2.0 μm. The thickness of the liner portions 12 and 22 is preferably about 0.01 μm to 2.5 μm. The thickness of the conductive material portions 13 and 23 is preferably about 0.01 μm to 2.5 μm.

  1 and 2, the liner portions 12 and 22 have a single-layer structure or a two-layer structure, but the liner portion may be formed of three or more layers. In this case, at least one of the plurality of layers and the conductive material part forming the liner part may be a cobalt-containing part. Examples of the layer constituting the liner part include a cobalt-containing layer (cobalt-containing part), a tantalum-containing layer (tantalum-containing part), a titanium-containing layer (titanium-containing part), a tungsten-containing layer (tungsten-containing part), and a ruthenium-containing layer. A layer (ruthenium-containing part).

  In the first polishing step, from the state shown in FIG. 1 (a) to the state shown in FIG. 1 (b), or from the state shown in FIG. 2 (a) to the state shown in FIG. 2 (b). The conductive material portions 13 and 23 are polished. In the first polishing step, the conductive material portions 13 and 23 on the surface of the substrate 10a or the substrate 20a before polishing are, for example, for a metal (conductive material) having a sufficiently high polishing rate ratio of the conductive material portion / liner portion. Polishing is performed by CMP using the above-described CMP polishing liquid. Thereby, the conductive material portions 13 and 23 on the convex portion are removed, the liner portion 12 and the second liner portion 22a are exposed on the surface, and the conductive pattern (that is, the wiring pattern) in which the conductive material portion is left in the concave portion. ) Is obtained. For example, when the conductive material portions 13 and 23 contain cobalt, it is preferable to use the CMP polishing liquid of this embodiment as the CMP polishing liquid for the conductive material. Thereby, while being able to grind | polish the electroconductive substance parts 13 and 23 with the grinding | polishing speed | rate of a favorable range, the etching of the electroconductive substance parts 13 and 23 can be suppressed.

  The conductive material portions 13 and 23 are copper, copper alloy, copper oxide, copper-based metal such as copper alloy, tungsten, tungsten alloy and other tungsten-based metal, silver, In the case of a noble metal such as gold, the CMP polishing liquid described in Japanese Patent No. 3337464 may be used as the CMP polishing liquid for the conductive material. In the first polishing step, the conductive material portions 13 and 23 together with the liner portion 12 and the second liner portion 22a on the convex portion may be polished.

  In the second polishing step, the liner portion 12 exposed in the first polishing step is polished from the state shown in FIG. 1B to the state shown in FIG. 1C, and the excess liner portion 12 is removed. To do. For example, when the liner part 12 contains cobalt, it is preferable to use the CMP polishing liquid of the present embodiment in the polishing step.

  Further, as shown in FIG. 2, when the liner portion 22 has the second liner portion 22a and the first liner portion 22b, the state shown in FIG. From the state until the state shown in FIG. 2C, the second liner portion 22a and the first liner portion 22b are polished, and the excess second liner portion 22a and the first liner portion 22b are removed. For example, when the second liner portion 22a contains cobalt, the second liner portion 22a is polished with the CMP polishing liquid of the present embodiment, and the polishing is terminated when the first liner portion 22b is exposed. The first liner portion 22b may be polished with a CMP polishing liquid for polishing the first liner portion 22b. Further, as a series of steps, the second liner portion 22a and the first liner portion 22b may be polished with the CMP polishing liquid of the present embodiment.

  Further, when the conductive material portions 13 and 23 contain cobalt, the second polishing is performed even when the liner portion 12, the second liner portion 22a, and the first liner portion 22b do not contain cobalt. It is preferable to use the CMP polishing liquid of this embodiment in the process. Thereby, the etching of the conductive material portions 13 and 23 in the second polishing step is suppressed, and a good wiring pattern can be formed.

  The insulating material portions 11 and 21 under the convex liner portions 12 and 22 are all exposed, and the conductive material portions 13 and 23 to be a wiring pattern are left in the concave portion, and the liner portion 12 is formed at the boundary between the convex portion and the concave portion. , 22 is finished when the substrate 10c or the substrate 20c having a desired pattern in which the cross-sections are exposed is obtained. Further, the conductive material portions 13 and 23 embedded in the recesses may be polished together with the liner portions 12 and 22.

  In each polishing step, the polishing surface plate is supplied while supplying the CMP polishing liquid between the polishing pad and the substrate while pressing the substrate with the surface to be polished facing the polishing pad on the polishing pad of the polishing surface plate. The surface to be polished is polished by relatively moving the substrate.

  As an apparatus used for polishing, a general polishing apparatus having a holder for holding a substrate to be polished, and a polishing platen connected to a motor whose rotation speed can be changed and a polishing pad attached thereto can be used. . As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation.

The polishing conditions are not particularly limited, but the rotation speed of the polishing surface plate is preferably a low rotation speed of 200 min ⁻¹ or less so that the substrate does not pop out. The pressure for pressing the substrate against the polishing pad is preferably 1 to 100 kPa, and more preferably 5 to 50 kPa in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern.

  During polishing, the CMP polishing liquid of this embodiment can be continuously supplied between the polishing pad and the surface to be polished by a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with a CMP 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 CMP with the surface state of the polishing pad always the same, it is preferable to perform a polishing pad conditioning step before polishing. For example, using a dresser with diamond particles, the polishing pad is conditioned with a liquid containing at least water. Subsequently, it is preferable to add a substrate cleaning step after performing the polishing method of the present embodiment.

  On the wiring pattern thus formed, a second layer insulating material portion, a liner portion, and a conductive material portion are further formed and polished to form a smooth surface over the entire surface of the semiconductor substrate. can do. By repeating this step a predetermined number, a semiconductor device having a desired number of wiring layers can be manufactured.

  The CMP polishing liquid of this embodiment can be used not only for polishing a semiconductor substrate as described above but also for polishing a substrate such as a magnetic head.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples, unless it deviates from the technical idea of this invention. For example, the type of CMP polishing liquid and the blending ratio thereof may be other types and ratios than those described in this example, and the composition and structure of the polishing target are also described in this example. A composition and structure other than the composition and structure may be used.

(CMP polishing liquid preparation method)
A CMP polishing liquid was prepared by the following method using each component shown in Tables 1 to 5.

(Examples 1-19 and Comparative Examples 1-4)
Abrasive grains of the types shown in Tables 1 to 5, aromatic dicarboxylic acids, organic acid components, metal anticorrosives, organic solvents, and additives are put in a container, and ultrapure water is poured and stirred. Mix to dissolve all components. Next, hydrogen peroxide water (30% by mass aqueous solution) was added as an oxidizing agent, and then ultrapure water was added to make 100 parts by mass as a whole to obtain a CMP polishing liquid.

  The content of each component is as shown in Tables 1-5. The content of abrasive grains was shown as mass% of “silica particles”, and the content of oxidizing agent was shown as mass% of hydrogen peroxide (30 mass% aqueous solution). Moreover, the average particle diameter (average secondary particle diameter) of the colloidal silica as an abrasive grain was measured according to the above-mentioned method. The results are shown in Tables 1-5.

(Measurement method of pH)
The pH of the CMP polishing liquid was measured according to the following.
Measurement temperature: 25 ° C
Measuring instrument: “pHMeter F-51” manufactured by Horiba, Ltd.
Measurement method: standard buffer (phthalate pH buffer solution pH: 4.01 (25 ° C.), neutral phosphate pH buffer solution pH: 6.86 (25 ° C.), borate pH buffer solution pH: 9 After calibrating three points using .18 (25 ° C.), the electrode was placed in a CMP polishing liquid, and the value after 3 minutes had elapsed and stabilized was measured, and the results are shown in Tables 1 to 5.

(Evaluation of polishing characteristics)
The CMP polishing liquids of Examples 1 to 19 and Comparative Examples 1 to 4 were evaluated according to the following items.

(1) Cobalt polishing rate (Co-RR (Removal Rate) [nm / min])
Using each of the resulting polishing liquids, the substrate to be polished was polished under the following conditions, and the cobalt polishing rate was calculated by dividing the difference in thickness of the cobalt layer before and after polishing by the polishing time. In addition, the thickness of the cobalt layer before and after polishing was calculated by a method of measuring electric resistance (resistance value) and converting from the measured value. For the measurement of the resistance value, a metal film thickness measuring device “RT-70” manufactured by Napson Corporation was used. The calculated cobalt polishing rate (Co-RR) [nm / min] is shown in Tables 1-5.
(Polishing conditions)
Polishing substrate: 20 mm × 20 mm chip obtained by cutting a blanket substrate obtained by forming a cobalt layer having a thickness of 200 nm on a silicon substrate (8 inch diameter wafer) Polishing apparatus: IMPTECH 10DVT manufactured by Nippon Engis Co., Ltd.
Polishing pad: Polishing pad made of polyurethane foam resin Surface plate rotation speed: 90 min ⁻¹
Polishing pressure: 33.1 kPa (4.8 psi)
Supply amount of CMP polishing liquid: 15 mL / min
Polishing time: 1 min

(2) Cobalt etching rate (Co-ER (Etching Rate) [nm / min])
The substrate was immersed in each polishing liquid obtained under the following conditions, and the cobalt etching rate was calculated by dividing the difference in thickness of the cobalt layer before and after immersion by the immersion time. In addition, the thickness of the cobalt layer before and after immersion was calculated by a method of measuring electric resistance (resistance value) and converting from the measured value. For the measurement of the resistance value, a metal film thickness measuring device “RT-70” manufactured by Napson Corporation was used. The calculated cobalt etching rate (Co-ER) [nm / min] is shown in Tables 1-5.
(Immersion conditions)
Substrate: 20 mm × 20 mm chip obtained by cutting a blanket substrate obtained by forming a 200 nm thick cobalt layer on a silicon substrate (8 inch diameter wafer) Polishing liquid capacity: 100 mL in a 100 mL beaker
Polishing liquid temperature: 60 ° C
Stirring speed: 200 min ⁻¹
Immersion time: 5 min

  From Tables 1-5, in Examples 1-19, it turns out that the etching rate of a cobalt layer is suppressed. Moreover, in Examples 1-19, while the etching rate of a cobalt layer is suppressed, it turns out that a cobalt layer can be grind | polished at a moderate grinding | polishing rate.

  According to the CMP polishing liquid and polishing method of this embodiment, etching of the cobalt-containing part can be suppressed while maintaining a good polishing rate of the cobalt-containing part as compared with the case where a conventional CMP polishing liquid is used.

  DESCRIPTION OF SYMBOLS 1, 11, 21 ... Insulating material part, 2, 12, 22 ... Liner part, 3, 13, 23 ... Conductive substance part, 10a, 10b, 10c, 20a, 20b, 20c ... Substrate, 22a ... 2nd liner Part, 22b ... 1st liner part.

Claims (10)

An aromatic carboxylic acid compound having a total of 2 carboxylic acid groups and carboxylic acid groups, and water,
The aromatic carboxylic acid compound has a structure in which another carboxylic acid group or carboxylate group is bonded to the ortho position of one carboxylic acid group or carboxylate group;
A CMP polishing liquid for cobalt polishing, having a pH exceeding 4.0.   The CMP according to claim 1, wherein the aromatic carboxylic acid compound has a carboxylic acid group or a carboxylic acid group at each of the 1-position and the 2-position of the aromatic ring, and an alkyl group at the 4-position of the aromatic ring. Polishing fluid.   The CMP polishing liquid according to claim 2, wherein the alkyl group has 1 to 3 carbon atoms.   The CMP polishing liquid according to any one of claims 1 to 3, wherein the aromatic carboxylic acid compound is 4-methylphthalic acid or a salt thereof.   The CMP polishing liquid according to any one of claims 1 to 4, further comprising abrasive grains.   The CMP polishing liquid according to claim 1, further comprising an organic acid component other than the aromatic carboxylic acid compound.   The CMP polishing liquid according to any one of claims 1 to 6, further comprising a metal oxidizing agent.   The CMP polishing liquid according to claim 1, further comprising a metal anticorrosive.   The CMP polishing liquid according to any one of claims 1 to 8, further comprising an organic solvent.   A polishing method for polishing a surface to be polished containing cobalt using the CMP polishing liquid according to claim 1.

Images