JP2014060250A - Polishing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition which is suitable for polishing an object to be polished having a metal wiring layer, suppresses a temporal change in polishing performance, and is excellent in storage stability including appearance changes such as discoloration and generation of a precipitate.SOLUTION: The polishing composition used for polishing an object to be polished having a metal wiring layer contains a complexing agent, an anticorrosive agent, a decomposition inhibitor for the anticorrosive agent, and water. The decomposition inhibitor for the anticorrosive agent is at least one selected from the group consisting of charged amino acids. It is preferable that the decomposition inhibitor for the anticorrosive agent is at least one selected from the group consisting of basic charged amino acids.

Description

  The present invention relates to a polishing composition. The present invention also relates to a polishing method and a substrate manufacturing method using the polishing composition.

  The present invention relates to a polishing composition for a substrate surface (hereinafter referred to as “polishing object”) containing a metal in, for example, a semiconductor integrated circuit (hereinafter referred to as “LSI”).

  Along with higher integration and higher speed of LSI, new fine processing technology has been developed. Chemical mechanical polishing (hereinafter referred to as “CMP”) is one of them, and planarization of an interlayer insulating film, formation of contact plugs, embedded wiring in an LSI manufacturing process, particularly a multilayer wiring forming process. Has been applied to the formation of. This technique is disclosed in Patent Document 1, for example.

  In the formation of contact plugs, tungsten is used as a filling material and a material for its interdiffusion barrier. In forming the contact plug, a manufacturing method is used in which an extra portion other than the contact plug is removed by CMP. Also, in the formation of embedded wiring, recently, in order to improve the performance of LSIs, attempts have been made to use copper or copper alloys as metal wiring as a wiring material. Since copper or copper alloy is difficult to be finely processed by the dry etching method frequently used in the formation of conventional aluminum alloy wiring, a thin film of copper or copper alloy is formed on an insulating film in which grooves have been formed in advance. A so-called damascene method is mainly employed in which the thin film other than the groove is deposited and buried, and the buried wiring is formed by removing the thin film by CMP. In the polishing composition for metals used in CMP, it generally contains a polishing accelerator such as an acid and an oxidizing agent, and further contains abrasive grains as necessary. It has also been proposed to use a polishing composition to which an anticorrosive agent is further added in order to improve the flatness of the polished object after polishing. For example, Patent Document 2 discloses the use of a polishing composition containing aminoacetic acid and / or amidosulfuric acid, an oxidizing agent, benzotriazole, and water.

  However, on the other hand, when an oxidizing agent is added to the polishing composition, a problem relating to storage stability in which the polishing performance changes with time is recognized. Various factors have been confirmed for changes in polishing performance. One factor is that chemical substances in polishing compositions such as polishing accelerators and anticorrosives interact with oxidants and change pH. Can be mentioned.

  In designing a polishing composition for metal, pH is very important, and it is generally performed based on a Pourbaix diagram. For example, for a polishing composition for copper, Patent Document 3 discloses that a pH of about 6.0 is important in order to form copper (I) oxide. When the pH of the polishing composition is lowered, copper oxide is less likely to be formed on the copper surface, and the dissolution of the metal is increased. Moreover, when the pH of the polishing composition is increased, the removed copper may precipitate from the solution and adhere to the wafer surface to cause scratches. Therefore, metal polishing compositions are required to stabilize the pH during polishing in order to ensure a flat surface free of defects after CMP. Patent Document 4 is disclosed as a technique for stabilizing the pH of such a polishing composition during copper polishing.

JP-A-62-102543 JP-A-8-83780 JP 2000-501771 A Special table 2006-506809 gazette

  As a result of studies by the present inventors, it has been found that the polishing compositions described in Patent Document 3 and Patent Document 4 are not sufficient for solving the storage stability problem in which the polishing performance changes with time. In order to suppress the change in polishing performance over time and to improve the storage stability including changes in appearance such as discoloration of the polishing composition and generation of precipitates, the polishing composition used in the CMP method Further improvements are urgently needed.

  Accordingly, the present invention provides a polishing composition used for polishing a polishing object having a metal wiring layer, which suppresses changes in polishing performance over time and improves storage stability including appearance. It is an object of the present invention to provide a possible means.

  This inventor repeated earnest research in order to solve the said subject. As a result, the conventional technology for stabilizing the pH alone is not sufficient to improve the storage stability of the polishing composition, and the complexing agent, anticorrosive agent, and specific anticorrosion agent in the polishing composition. It has been found that the above-mentioned problems can be solved by including an agent decomposition inhibitor, and the present invention has been completed.

  That is, one embodiment of the present invention is a polishing composition used for polishing a polishing object having a metal wiring layer. The polishing composition includes at least one selected from the group consisting of a complexing agent, an anticorrosive agent, an anticorrosive agent decomposition inhibitor, and water, and the anticorrosive agent decomposition inhibitor comprises a charged amino acid. It is characterized by a certain point.

  According to the present invention, in a polishing composition used for polishing a polishing object having a metal wiring layer, change in polishing performance over time can be suppressed and storage stability including appearance can be improved. It becomes.

  The present invention is a polishing composition used for polishing a polishing object having a metal wiring layer, and includes an anticorrosive, an anticorrosive agent, a water inhibitor, and the anticorrosive agent agent. Is a polishing composition which is at least one selected from the group consisting of charged amino acids. By adopting such a configuration, the change in polishing performance over time is suppressed, and the storage stability including appearance such as discoloration and precipitation (hereinafter, maintenance of polishing performance over time of the polishing composition is maintained). And the appearance of the polishing composition, such as discoloration and the presence or absence of precipitates, is collectively referred to as “storage stability”).

  Although the detailed reason why the storage stability of the polishing composition is improved by using the polishing composition of the present invention is unknown, the decrease in the storage stability of the polishing composition is caused by the decomposition of the anticorrosive agent. It is thought that. In particular, it is considered that the storage stability is lowered by the complexing agent in the polishing composition decomposing or adsorbing a nitrogen binding site such as an azole skeleton of the anticorrosive. In contrast, charged amino acids maintain the stability of the anticorrosive agent by adsorbing and hydrating the nitrogen binding sites such as the azole skeleton of the anticorrosive agent over the complexing agent, resulting in a polishing composition. It is considered that the storage stability of is improved. In addition, the said mechanism is based on estimation and this invention is not limited to the said mechanism at all.

[Polishing object]
First, an example of a polishing object and a semiconductor wiring process according to the present invention will be described. The semiconductor wiring process usually includes the following steps, but the present invention is not limited to the use of the following steps.

  A barrier layer and a metal wiring layer are sequentially formed on an insulator layer having a trench provided on the substrate. Prior to the formation of the metal wiring layer, the barrier layer is formed on the insulator layer so as to cover the surface of the insulator layer. The thickness of the barrier layer is smaller than the depth and width of the trench. Following the formation of the barrier layer, the metal wiring layer is formed on the barrier layer so that at least the trench is filled.

  When removing at least the outer portion of the metal wiring layer and the outer portion of the barrier layer by CMP, first, most of the outer portion of the metal wiring layer is removed. Next, the remainder of the outer portion of the metal wiring layer is removed to expose the upper surface of the outer portion of the barrier layer.

  Thereafter, at least a portion of the metal wiring layer located outside the trench and a portion of the barrier layer located outside the trench are removed by CMP. As a result, at least a part of the part of the barrier layer located in the trench and at least a part of the part of the metal wiring layer located in the trench remain on the insulator layer. That is, a part of the barrier layer and a part of the metal wiring layer remain inside the trench. Thus, the portion of the metal wiring layer remaining inside the trench functions as a wiring.

  The polishing composition of the present invention is used for polishing a polishing object having the metal wiring layer and the barrier layer as described above.

  The metal contained in the metal wiring layer is not particularly limited, and examples thereof include copper, aluminum, hafnium, cobalt, nickel, titanium, and tungsten. These metals may be contained in the metal wiring layer in the form of an alloy or a metal compound. Copper or copper alloy is preferable. These metals may be used alone or in combination of two or more.

  Moreover, it does not restrict | limit especially as a metal contained in a barrier layer, For example, noble metals, such as a metal of titanium and a tantalum, and ruthenium, silver, gold | metal | money, palladium, platinum, rhodium, iridium, and osmium are mentioned. These metals and noble metals may be contained in the barrier layer in the form of an alloy or a metal compound, and may be used alone or in combination of two or more.

Next, the structure of the polishing composition of the present invention will be described in detail.
[Complexing agent]
The polishing composition according to this embodiment contains a complexing agent. When a complexing agent is added to the polishing composition, there is an advantageous effect that the polishing rate of the object to be polished by the polishing composition is improved by the etching action of the complexing agent.

  As the complexing agent, for example, inorganic acids, organic acids, amino acids, nitrile compounds, chelating agents and the like can be used. Specific examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, carbonic acid and the like. Specific examples of organic acids 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, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, malein Examples include acid, phthalic acid, malic acid, tartaric acid, citric acid, and lactic acid. Organic sulfuric acids such as methanesulfonic acid, ethanesulfonic acid and isethionic acid can also be used. A salt such as an alkali metal salt of an inorganic acid or an organic acid may be used instead of the inorganic acid or the organic acid or in combination with the inorganic acid or the organic acid. Of these, glycine, alanine, malic acid, tartaric acid, citric acid, glycolic acid, isethionic acid or salts thereof are preferred.

  Specific examples of the nitrile compound include acetonitrile, aminoacetonitrile, propionitrile, butyronitrile, isobutyronitrile, benzonitrile, glutaronitrile, methoxyacetonitrile, and the like.

  Specific examples of chelating agents include nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylenediamine-N, N, N ′, N′-tetramethylenesulfonic acid, transcyclohexane Diamine tetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diamine tetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), N- (2-carboxylateethyl) -L-aspartic acid, β -Alanine diacetate, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid 1,2-dihydroxybenzene-4,6 Such as disulfonic acid and the like.

  When the polishing composition according to this embodiment contains a complexing agent, the lower limit of the content of the complexing agent in the polishing composition is 0.01% by mass or more with respect to 100% by mass of the total amount of the composition. It is preferable that it is 0.1 mass% or more. As the content of the complexing agent increases, the polishing rate of the object to be polished by the polishing composition is improved. On the other hand, the upper limit of the content of the complexing agent in the polishing composition from the viewpoint of reducing the possibility that the polishing object is easily excessively etched by adding the complexing agent (preventing excessive etching). Is preferably 10% by mass or less, more preferably 1% by mass or less, with respect to 100% by mass of the total amount of the composition.

[Anticorrosive]
Polishing composition which concerns on this form contains a corrosion inhibitor. By adding an anticorrosive agent to the polishing composition, it is possible to further suppress the formation of a dent on the side of the wiring in the polishing using the polishing composition. In addition, it is possible to further suppress the occurrence of step defects such as dishing on the surface of the object to be polished after polishing with the polishing composition.

  The usable anticorrosive agent is not particularly limited, but is preferably a heterocyclic compound. The number of heterocyclic rings in the heterocyclic compound is not particularly limited. The heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. These anticorrosives may be used alone or in combination of two or more. The anticorrosive agent may be a commercially available product or a synthetic product.

  Specific examples of heterocyclic compounds that can be used as anticorrosives include, for example, pyrrole compounds, pyrazole compounds, imidazole compounds, triazole compounds, tetrazole compounds, pyridine compounds, pyrazine compounds, pyridazine compounds, pyridine compounds, indolizine compounds, indole compounds. , Isoindole compound, indazole compound, purine compound, quinolidine compound, quinoline compound, isoquinoline compound, naphthyridine compound, phthalazine compound, quinoxaline compound, quinazoline compound, cinnoline compound, buteridine compound, thiazole compound, isothiazole compound, oxazole compound, isoxazole And nitrogen-containing heterocyclic compounds such as compounds and furazane compounds.

  More specific examples include pyrazole compounds such as 1H-pyrazole, 4-nitro-3-pyrazolecarboxylic acid, 3,5-pyrazolecarboxylic acid, 3-amino-5-phenylpyrazole, 5 -Amino-3-phenylpyrazole, 3,4,5-tribromopyrazole, 3-aminopyrazole, 3,5-dimethylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3-methylpyrazole, 1-methyl Pyrazole, 3-amino-5-methylpyrazole, 4-amino-pyrazolo [3,4-d] pyrimidine, allopurinol, 4-chloro-1H-pyrazolo [3,4-D] pyrimidine, 3,4-dihydroxy-6 -Methylpyrazolo (3,4-B) -pyridine, 6-methyl-1H-pyrazolo [3,4-b] pyridine - amine.

  Examples of imidazole compounds include, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, benzimidazole, 5,6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole, 2-methylbenzimidazole, 2- (1-hydroxyethyl) benzimidazole, 2-hydroxybenzimidazole, 2-phenylbenzimidazole, 2 , 5-dimethylbenzimidazole, 5-methylbenzimidazole, 5-nitrobenzimidazole, 1H-purine and the like.

  Examples of triazole compounds include, for example, 1,2,3-triazole, 1,2,4-triazole, 1-methyl-1,2,4-triazole, methyl-1H-1,2,4-triazole-3. -Carboxylate, 1,2,4-triazole-3-carboxylic acid, methyl 1,2,4-triazole-3-carboxylate, 1H-1,2,4-triazole-3-thiol, 3,5-diamino -1H-1,2,4-triazole, 3-amino-1,2,4-triazole-5-thiol, 3-amino-1H-1,2,4-triazole, 3-amino-5-benzyl-4H -1,2,4-triazole, 3-amino-5-methyl-4H-1,2,4-triazole, 3-nitro-1,2,4-triazole, 3-bromo-5-nitro-1, , 4-tri Sol, 4- (1,2,4-triazol-1-yl) phenol, 4-amino-1,2,4-triazole, 4-amino-3,5-dipropyl-4H-1,2,4-triazole 4-amino-3,5-dimethyl-4H-1,2,4-triazole, 4-amino-3,5-dipeptyl-4H-1,2,4-triazole, 5-methyl-1,2,4 -Triazole-3,4-diamine, 1H-benzotriazole, 1-hydroxybenzotriazole, 1-aminobenzotriazole, 1-carboxybenzotriazole, 5-chloro-1H-benzotriazole, 5-nitro-1H-benzotriazole, 5-carboxy-1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazo 1- (1 ′, 2′-dicarboxyethyl) benzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl ] -5-methylbenzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] -4-methylbenzotriazole, and the like.

Examples of the tetrazole compound include 1H-tetrazole, 5-methyltetrazole, 5-aminotetrazole, and 5-phenyltetrazole.
Examples of indazole compounds include, for example, 1H-indazole, 5-amino-1H-indazole, 5-nitro-1H-indazole, 5-hydroxy-1H-indazole, 6-amino-1H-indazole, 6-nitro-1H -Indazole, 6-hydroxy-1H-indazole, 3-carboxy-5-methyl-1H-indazole and the like.

  Examples of indole compounds include 1H-indole, 1-methyl-1H-indole, 2-methyl-1H-indole, 3-methyl-1H-indole, 4-methyl-1H-indole, 5-methyl-1H- Indole, 6-methyl-1H-indole, 7-methyl-1H-indole, 4-amino-1H-indole, 5-amino-1H-indole, 6-amino-1H-indole, 7-amino-1H-indole, 4-hydroxy-1H-indole, 5-hydroxy-1H-indole, 6-hydroxy-1H-indole, 7-hydroxy-1H-indole, 4-methoxy-1H-indole, 5-methoxy-1H-indole, 6- Methoxy-1H-indole, 7-methoxy-1H-indole, 4-chloro-1H- Ndole, 5-chloro-1H-indole, 6-chloro-1H-indole, 7-chloro-1H-indole, 4-carboxy-1H-indole, 5-carboxy-1H-indole, 6-carboxy-1H-indole, 7-carboxy-1H-indole, 4-nitro-1H-indole, 5-nitro-1H-indole, 6-nitro-1H-indole, 7-nitro-1H-indole, 4-nitrile-1H-indole, 5- Nitrile-1H-indole, 6-nitrile-1H-indole, 7-nitrile-1H-indole, 2,5-dimethyl-1H-indole, 1,2-dimethyl-1H-indole, 1,3-dimethyl-1H- Indole, 2,3-dimethyl-1H-indole, 5-amino-2,3-dimethyl-1H- Ndole, 7-ethyl-1H-indole, 5- (aminomethyl) indole, 2-methyl-5-amino-1H-indole, 3-hydroxymethyl-1H-indole, 6-isopropyl-1H-indole, 5-chloro -2-methyl-1H-indole and the like.

  Among these, a preferable heterocyclic compound is a nitrogen-containing five-membered ring compound, and specifically, pyrazole, tetrazole, and 1,2,4-triazole are preferable. Since these heterocyclic compounds have high chemical or physical adsorptive power to the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in improving the flatness of the surface of the object to be polished after polishing using the polishing composition of the present invention.

  The lower limit of the content of the anticorrosive agent in the polishing composition is preferably 0.001 g / L or more, more preferably 0.005 g / L or more, and 0.01 g / L or more. Further preferred. Further, the upper limit of the content of the anticorrosive agent in the polishing composition is preferably 10 g / L or less, more preferably 5 g / L or less, and even more preferably 1 g / L or less. If it is such a range, the level | step difference of the grinding | polishing target object after grind | polishing using a polishing composition will reduce, and the grinding | polishing speed | rate of the grinding | polishing target object by polishing composition will improve.

[Anti-corrosion agent decomposition inhibitor]
The polishing composition according to this embodiment contains a charged amino acid as an anticorrosive agent decomposition inhibitor. Examples of the charged amino acid used in the present invention include basic charged amino acids such as arginine and acidic charged amino acids such as aspartic acid. These charged amino acids may be used alone or in combination of two or more.

  Among these charged amino acids, preferred are basic charged amino acids, specifically arginine, lysine, and histidine. A basic charged amino acid is preferable because the effects of the present invention can be obtained more efficiently.

  The lower limit of the charged amino acid content (concentration) in the polishing composition of the present invention is preferably 0.01 g / L or more, more preferably 0.05 g / L or more, and 0.1 g / L. More preferably, it is L or more. Further, the upper limit of the content (concentration) of the charged amino acid in the polishing composition of the present invention is preferably 100 g / L or less, more preferably 50 g / L or less, and 5 g / L or less. More preferably. If it is this range, the effect of this invention can be acquired more efficiently. As used herein, “charged amino acid” refers to an amino acid having a charged side chain in its structure.

[PH of polishing composition]
The pH of the polishing composition is not particularly limited. However, if the pH is 9 or less, more specifically 8 or less, the polishing composition can be easily handled. Moreover, if it is 5 or more, and more specifically 6 or more, the dispersibility of the said abrasive grain will improve when the polishing composition contains an abrasive grain.

  A pH adjusting agent may be used to adjust the pH of the polishing composition to a desired value. The pH adjuster to be used may be either acid or alkali, and may be any of inorganic and organic compounds. These pH regulators can be used alone or in combination of two or more.

[water]
The polishing composition of the present invention contains water as a dispersion medium or solvent for dispersing or dissolving each component. From the viewpoint of suppressing the inhibition of the action of other components, water containing as little impurities as possible is preferable. Specifically, after removing impurity ions with an ion exchange resin, pure water from which foreign matters are removed through a filter is used. Water, ultrapure water, or distilled water is preferred.

[Other ingredients]
The polishing composition of the present invention is an organic solvent for dissolving abrasive grains, preservatives, antifungal agents, oxidizing agents, reducing agents, water-soluble polymers, surfactants, poorly soluble organic substances as necessary. And other components may be further included. Hereinafter, the abrasive grains, the surfactant and the oxidizing agent, which are other preferable components, will be described.

[Abrasive grain]
The polishing composition according to this embodiment may contain abrasive grains as an optional additive. The abrasive grains contained in the polishing composition have an action of mechanically polishing an object to be polished. The polishing rate of the object to be polished by the composition is improved.

The abrasive used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of metal oxides such as silica, alumina, ceria, titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. These abrasive grains may be used alone or in combination of two or more. The abrasive grains may be commercially available products or synthetic products.
Among these abrasive grains, silica is preferable, and colloidal silica is particularly preferable.

  The abrasive grains may be surface-modified. Since ordinary colloidal silica has a zeta potential value close to zero under acidic conditions, silica particles are not electrically repelled with each other under acidic conditions and are likely to agglomerate. On the other hand, abrasive grains whose surfaces are modified so that the zeta potential has a relatively large negative value even under acidic conditions are strongly repelled from each other and dispersed well even under acidic conditions, resulting in storage of the polishing composition. Stability will be improved. Such surface-modified abrasive grains can be obtained, for example, by mixing a metal such as aluminum, titanium or zirconium or an oxide thereof with the abrasive grains and doping the surface of the abrasive grains.

  Of these, colloidal silica having an organic acid immobilized thereon is particularly preferable. The organic acid is immobilized on the surface of the colloidal silica contained in the polishing composition, for example, by chemically bonding a functional group of the organic acid to the surface of the colloidal silica. If the colloidal silica and the organic acid are simply allowed to coexist, the organic acid is not fixed to the colloidal silica. For immobilizing sulfonic acid, which is a kind of organic acid, on colloidal silica, see, for example, “Sulphonic acid-functionalized silica through quantitative oxides of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica, and then the sulfonic acid is immobilized on the surface by oxidizing the thiol group with hydrogen peroxide. The colloidal silica thus obtained can be obtained. Alternatively, if the carboxylic acid is to be immobilized on colloidal silica, for example, “Novel Silene Coupling Agents Containing a Photolabile 2 Nitrobenzyl Ester for Induction of the Carbon Group” -229 (2000). Specifically, colloidal silica having a carboxylic acid immobilized on the surface can be obtained by irradiating light after coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica. .

  The lower limit of the average primary particle diameter of the abrasive grains is preferably 5 nm or more, more preferably 7 nm or more, and further preferably 10 nm or more. Further, the upper limit of the average primary particle diameter of the abrasive grains is preferably 500 nm or less, more preferably 100 nm or less, and further preferably 70 nm or less. Within such a range, the polishing rate of the polishing object with the polishing composition is improved, and step defects such as dishing occur on the surface of the polishing object after polishing with the polishing composition. Can be further suppressed. In addition, the average primary particle diameter of an abrasive grain is calculated based on the specific surface area of the abrasive grain measured by BET method, for example.

  The lower limit of the content of the abrasive grains in the polishing composition is preferably 0.005% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more. Most preferably, it is 3 mass% or more. Further, the upper limit of the content of the abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 30% by mass, and further preferably 15% by mass or less. Within such a range, the polishing rate of the polishing object can be improved, and the cost of the polishing composition can be reduced, and dishing is performed on the surface of the polishing object after polishing using the polishing composition. It is possible to further suppress the occurrence of step defects such as.

[Surfactant]
The polishing composition according to this embodiment may contain a surfactant as an optional additive. The surfactant may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

  Examples of anionic surfactants include, for example, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfuric acid ester, alkyl sulfuric acid ester, polyoxyethylene alkyl ether sulfuric acid, alkyl ether sulfuric acid, alkylbenzene sulfonic acid, alkyl phosphoric acid ester , Polyoxyethylene alkyl phosphate ester, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof.

  Examples of the cationic surfactant include alkyl trimethyl ammonium salt, alkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt, alkyl amine salt and the like.

  Examples of amphoteric surfactants include alkyl betaines and alkyl amine oxides.

  Examples of nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, and alkyl alkanolamide. Is mentioned.

  Among these, preferable surfactants are polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, alkylbenzene sulfonate, and polyoxyethylene alkyl ether. Since these surfactants have a high chemical or physical adsorption force to the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in reducing the level difference of the object to be polished after polishing using the polishing composition of the present invention.

  The lower limit of the content of the surfactant in the polishing composition is preferably 0.001 g / L or more, more preferably 0.005 g / L or more, and 0.01 g / L or more. Is more preferable. Further, the upper limit of the content of the surfactant in the polishing composition is preferably 10 g / L or less, more preferably 5 g / L or less, and further preferably 1 g / L or less. If it is such a range, the level | step difference of the grinding | polishing target object after grind | polishing using a polishing composition will reduce, and the grinding | polishing speed | rate of the grinding | polishing target object by polishing composition will improve.

[Oxidant]
The polishing composition according to this embodiment may contain an oxidizing agent as an optional component. In this specification, an oxidizing agent means a compound that can function as an oxidizing agent for a metal contained in an object to be polished. Therefore, the oxidizing agent can be selected according to the criterion of whether or not it has a redox potential sufficient to exhibit such a function. For this reason, the extension of the non-metallic oxidizer is not necessarily unambiguously defined, but as an example, for example, hydrogen peroxide, nitric acid, chlorous acid, hypochlorous acid, periodic acid, persulfate, hydrogen peroxide and its adducts such as urea hydrogen peroxide and carbonate, organic peroxides, such as benzoyl, peracetic acid, and di -t- butyl, sul fate _(SO 5), sul fate _{(S 5 O} 8), and Contains sodium peroxide. Periodic acid, iodic acid, hypoiodic acid, iodic acid, perbromic acid, bromic acid, hypobromic acid, bromic acid, perchloric acid, chloric acid, perchloric acid, perboric acid, and their salts Can be mentioned.

  When the polishing composition according to this embodiment contains an oxidizing agent, the lower limit of the content of the oxidizing agent in the polishing composition is 0.1% by mass or more with respect to 100% by mass of the total amount of the composition. It is preferable that the content is 0.3% by mass or more. As the content of the oxidizing agent increases, the polishing rate for the object to be polished by the polishing composition tends to improve. On the other hand, when the polishing composition according to this embodiment contains an oxidizing agent, the upper limit of the content of the oxidizing agent in the polishing composition is 10% by mass or less with respect to 100% by mass of the total amount of the composition. Preferably, it is 5 mass% or less. As the content of the oxidizing agent decreases, the material cost of the polishing composition can be reduced, and the load on the processing of the polishing composition after polishing, that is, the waste liquid treatment can be reduced. Moreover, the advantageous effect that excessive oxidation of the object to be polished by the oxidizing agent can be prevented is also obtained.

[Method for producing polishing composition]
The manufacturing method in particular of the polishing composition of this invention is not restrict | limited, For example, it can obtain by stirring and mixing the compound which produces an inorganic phosphate ion, and another component as needed.

  Although the temperature at the time of mixing each component is not specifically limited, 10-40 degreeC is preferable and you may heat in order to raise a dissolution rate. Further, the mixing time is not particularly limited.

[Polishing method and substrate manufacturing method]
As described above, the polishing composition of the present invention is suitably used for polishing a polishing object having a metal wiring layer and a barrier layer. Therefore, this invention provides the grinding | polishing method which grind | polishes the grinding | polishing target object which has a metal wiring layer and a barrier layer with the polishing composition of this invention. Moreover, this invention provides the manufacturing method of a board | substrate including the process of grind | polishing the grinding | polishing target object which has a metal wiring layer and a barrier layer with the said grinding | polishing method.

  As a polishing apparatus, a general holder having a polishing surface plate on which a holder for holding a substrate having a polishing object and a motor capable of changing the number of rotations are attached and a polishing pad (polishing cloth) can be attached. A polishing apparatus can be used.

  As the polishing pad, a general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used without particular limitation. It is preferable that the polishing pad is grooved so that the polishing liquid accumulates.

  The polishing conditions are not particularly limited, and for example, the rotation speed of the polishing platen is preferably 10 to 500 rpm, and the pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 to 10 psi. The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying with a pump or the like is employed. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

  After polishing is completed, the substrate is washed in running water, and water droplets adhering to the substrate are removed by a spin dryer or the like and dried to obtain a substrate having a metal wiring layer and a barrier layer.

  The present invention will be described in further detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

(Examples 1-10, Comparative Examples 1-19)
As shown in Table 1, charged amino acids or other amino acids (in the column of “amino acids” in the table), complexing agents, oxidizing agents, anticorrosives, surfactants and abrasive grains are stirred and mixed in water (mixing temperature: The polishing compositions of Examples 1 to 10 and Comparative Examples 1 to 19 were prepared at about 25 ° C. and mixing time: about 10 minutes. At this time, colloidal silica (content 1 mass%) having an average secondary particle diameter of about 70 nm (average primary particle diameter 35 nm, association degree 2) was used as the abrasive grains. As an anticorrosive, benzotriazole (content 0.02% by mass) was used. Alkyl sulfate (content 0.03% by mass) was used as the anionic surfactant, and polyoxyethylene alkyl ether (content 0.06% by mass) was used as the nonionic surfactant. Hydrogen peroxide (content: 1.0% by mass) was used as the oxidizing agent. Moreover, glycine (content 1.0 mass%) was used as a complexing agent. The pH of the composition was adjusted to 7.3 by adding potassium hydroxide (KOH) and confirmed with a pH meter. In addition, what is described as "-" in the column of "amino acid" in a table | surface shows that neither a charged amino acid nor another amino acid is contained.

(Confirmation of storage stability regarding appearance)
Using the obtained polishing composition, the presence or absence of discoloration after standing at 70 ° C. for 7 days and the presence or absence of abrasive grains were confirmed.
Presence / absence of discoloration: The color change immediately after the adjustment of each polishing composition and after standing at 70 ° C. for 7 days was visually confirmed, and the case where there was no discoloration after standing at 70 ° C. for 7 days was “−” “If the color change occurred after standing at 70 ° C. for 7 days, it was defined as“ + ”(“ color change ”column in the table).
Presence / absence of precipitation of abrasive grains: After confirming the color change immediately after adjustment of each polishing composition and after standing at 70 ° C. for 7 days, the precipitation of abrasive grains was observed even after standing at 70 ° C. for 7 days. In the case where there was not, “−”, precipitation of abrasive grains occurred after standing at 70 ° C. for 7 days, but when the abrasive grains were easily dispersed by shaking mixing, “+”, left standing at 70 ° C. for 7 days. After that, precipitation of abrasive grains occurred, and the case where the abrasive grains did not re-disperse even with shaking mixing was defined as “++” (“Abrasive precipitation” column in the table).

(Polishing speed)
Regarding the polishing rate, the polishing composition immediately after preparation and the polishing composition after standing at 70 ° C. for 7 days were used, and the surface of the copper blanket wafer was polished for 60 seconds under the polishing conditions shown in Table 3 below. The polishing rate was measured. The polishing rate was determined by dividing the difference in thickness of the copper blanket wafer before and after polishing measured by using a sheet resistance measuring instrument based on the DC 4 probe method by the polishing time.

  Table 1 shows the measurement results of the presence or absence of discoloration and precipitation of the abrasive grains, and Table 2 shows the measurement results of the polishing rate.

  As shown in Table 1 above, it was found that the polishing compositions of the present invention (Examples 1 to 7) can reduce step defects while maintaining a high polishing rate as compared with the polishing compositions of Comparative Examples. . Further, the polishing compositions of the present invention (Examples 8, 9 and 10) have a rate of change in the polishing rate immediately after production and after standing at 70 ° C. for 7 days, compared with the polishing compositions of the comparative examples. It was found to be low and exert an excellent effect on storage stability. As described above, the result that the rate of change of the polishing rate is small is that the interaction between the abrasive grains and the chemical additive in the polishing composition is small, and the stability of the anticorrosive agent that particularly affects the polishing rate is maintained. It is suggested.

Claims (5)

A polishing composition used for polishing a polishing object having a metal wiring layer,
A complexing agent;
Anticorrosive,
An anticorrosive decomposition inhibitor,
A polishing composition comprising water, wherein the anticorrosive agent decomposition inhibitor is at least one selected from the group consisting of charged amino acids.   The polishing composition according to claim 1, wherein the anticorrosive agent decomposition inhibitor is at least one selected from the group consisting of basic charged amino acids.   The polishing composition according to claim 1, wherein the anticorrosive agent decomposition inhibitor is at least one selected from the group consisting of acidic charged amino acids.   The grinding | polishing method which grind | polishes the grinding | polishing target object which has a metal wiring layer with the polishing composition as described in any one of Claims 1-3.   The manufacturing method of a board | substrate including the process of grind | polishing the grinding | polishing target object which has a metal wiring layer with the grinding | polishing method of Claim 4.