TWI600731B - Polishing agent and method of polishing substrate - Google Patents

Description

Abrasive and polishing method of substrate

The present invention relates to an abrasive and a method of polishing a substrate.

In recent years, a new microfabrication technology has been developed along with the high integration and high performance of a semiconductor integrated circuit (Large Scale Integration, hereinafter referred to as "LSI"). The chemical mechanical polishing (hereinafter referred to as "CMP") method is one of them, and is an LSI manufacturing step, in particular, planarization of an insulator, formation of a metal plug, formation of an embedded wiring, and the like in a multilayer wiring forming step. Frequently utilized technology.

In addition, recently, in order to improve the performance of LSI, it has been attempted to use a copper alloy as a wiring material. However, it is difficult for the copper alloy to perform microfabrication by a dry etching method frequently used in the formation of the prior aluminum alloy wiring. For this reason, for example, a so-called damascene method is mainly used, in which a copper alloy thin film is deposited on an insulating film in which a groove is formed in advance, and a copper alloy film other than the groove portion is removed by CMP to form an embedded wiring (see, for example, Patent Document 1) ).

A common method in metal CMP is to attach a polishing cloth to a circular polishing platen, impregnate the surface of the polishing cloth with a liquid metal abrasive, and press the surface of the substrate on which the metal film is formed. The polishing platen is rotated in a state where a predetermined pressure (hereinafter referred to as "polishing pressure") is applied to the back surface, and the metal film of the convex portion is removed by mechanical friction between the metal abrasive and the convex portion of the metal film.

The abrasive for metal used in CMP usually contains an oxidizing agent and grinding Granules, metal dissolving agents, metal corrosion inhibitors, etc. are added as needed. In the case where these substances are added, the basic mechanism is considered to be that the surface of the metal film is oxidized by a metal dissolving agent, and the oxide layer is ground by the abrasive grains. It is considered that the oxide layer on the surface of the metal film which is the concave portion is not in contact with the polishing cloth, and the grinding effect of the abrasive grains is not so. Therefore, the metal layer of the convex portion is removed as the CMP progresses, and the surface of the substrate is flattened.

On the other hand, as shown in FIG. 1( a ), a barrier metal conductor film is formed on the lower layer of the conductive material layer 5 including a wiring metal such as copper or a copper alloy (hereinafter also referred to as a barrier metal layer). 3"), the barrier metal conductor film is for preventing copper from diffusing into the insulator 2 formed on the ruthenium substrate 1, or improving adhesion. Therefore, it is necessary to remove the exposed barrier metal layer 3 by CMP other than the wiring portion for embedding the wiring metal.

Therefore, the application is divided into a "first polishing step" and a "second polishing step", and a two-stage polishing method in which polishing is performed using different polishing agents. The "first polishing step" is performed on the conductive material layer 5. The state shown in (a) of FIG. 1 is polished until the state shown in FIG. 1(b), and the "second polishing step" polishes the barrier metal layer 3 from the state shown in (b) of FIG. Up to the state shown in (c) of Fig. 1 .

Further, as the design rules are miniaturized, the layers of the wiring forming step tend to be thin. However, the barrier metal layer 3 is thinned, whereby the effect of preventing diffusion of the conductive material is lowered, for example, and the conductive material contains at least one selected from the group consisting of copper or a copper alloy and oxides thereof. Further, the wiring width is narrowed, whereby the embedding property of the conductive material is lowered, and a void called void is generated in the wiring portion. Further, with conduction The adhesion of the physical layer also tends to decrease. Therefore, research is being conducted to replace the metal used in the barrier metal layer 3 in Fig. 1 with a metal containing a Co (cobalt) element. Further, as shown in FIG. 2( a ), it is also proposed that a layer of a metal containing a cobalt element (hereinafter also referred to as “cobalt layer 4 ”) is interposed between the barrier metal layer 3 and the conductive material layer 5 . By using the cobalt layer 4, the diffusion of the conductive material is suppressed, and since the affinity between cobalt and copper which is widely used as a conductive material is high, the embedding property of the copper layer in the wiring portion is improved, and it can be further supplemented. The adhesion of the copper layer.

In the case where cobalt is used as the barrier metal layer, the abrasive for metal must remove the excess cobalt layer. Although various kinds of abrasives for metals are known, on the other hand, when there is a certain abrasive for metal, the abrasive for the metal does not necessarily remove any metal. As a conventional metal abrasive, it is known that a metal such as copper, tantalum, titanium, tungsten, or aluminum is used as a polishing target (object to be removed), but an abrasive using cobalt as a polishing target is not known.

However, cobalt is more corrosive than a conductive material such as copper which has been used as a wiring metal, and if a prior abrasive is used as it is, cobalt is excessively etched (etched) or cracks are formed in the wiring layer. Therefore, there is a possibility that the conductive metal ions are diffused without functioning as a barrier metal layer. In the case where metal ions are diffused into the insulator, the possibility of short-circuiting of the semiconductor device becomes high. On the other hand, if an anticorrosive agent having a strong anticorrosive effect is added to prevent such a situation, or an addition amount of the anticorrosive agent is increased, there is a problem that the overall polishing rate is lowered.

For such a problem, an abrasive using a specific metal corrosion inhibitor is known, and the specific metal corrosion inhibitor is a heterocyclic ring of a four-membered to six-membered ring. The compound contains two or more double bonds and contains one or more nitrogen atoms (for example, see Patent Document 2). According to such an abrasive, the wiring layer can be protected and cracks are prevented from occurring in the wiring layer.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 2-278822

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-91248

However, the etching of cobalt can be suppressed only by the action of the metal corrosion inhibitor, but it is not easy to maintain the high polishing rate for cobalt at the same time, and the polishing rate of cobalt is further improved. The present invention has been made to solve the above problems, and an object of the invention is to provide an abrasive and a method for polishing a substrate using the polishing agent, wherein the polishing agent maintains a good polishing rate against a cobalt layer, suppresses corrosion of a cobalt layer, and suppresses generation of cracks.

The inventors of the present invention have diligently studied to solve such a prior problem, and as a result, have found that a good polishing rate for a cobalt layer can be maintained by using a specific carboxylic acid derivative, and the cobalt layer is excellent in corrosion inhibition property. It can suppress the generation of cracks.

The specific means for solving the above problems are as follows.

<1> An abrasive for polishing a layer containing a cobalt element, comprising a carboxylic acid derivative, a metal corrosion inhibitor, and water, and having a pH of 4.0 or less, wherein the carboxylic acid derivative is selected from the group consisting of phthalic acid At least one of a group consisting of a formic acid compound, an isophthalic acid compound, an alkyl dicarboxylic acid compound represented by the following formula (I), and a salt or an acid anhydride thereof.

HOOC-R-COOH. . . (I)

In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms.

By setting it as such an abrasive, it is possible to maintain a good polishing rate for the cobalt layer and to improve corrosion inhibition.

<2> An abrasive for polishing a layer containing a cobalt element, comprising at least one of a carboxylic acid derivative, a metal corrosion inhibitor, and water, and having a pH of 4.0 or less, and an abrasive of 50 ° C for cobalt The etching rate is 10.0 nm/min or less, and the at least one or more carboxylic acid derivatives are selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and an alkyl dicarboxylic acid compound represented by the following formula (I). And a group consisting of these salts and anhydrides.

HOOC-R-COOH. . . (I)

In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms.

By setting it as such an abrasive, it is possible to maintain a good polishing rate for the cobalt layer and to improve corrosion inhibition.

The abrasive according to the above <1> or <2>, wherein the metal corrosion inhibitor contains a compound having a triazole skeleton.

Thereby, corrosion resistance can be suppressed more effectively.

The abrasive according to any one of <1> to <3> which further contains an oxidizing agent.

Thereby, when the film to be polished contains a layer other than the cobalt layer, the polishing rate of the layer other than the cobalt layer can be further increased.

The abrasive according to any one of <1> to <4> which further contains an organic solvent.

Thereby, when the film to be polished contains a layer other than the cobalt layer, the wettability of the layer other than the cobalt layer is improved, so that the polishing rate can be further increased.

The abrasive according to any one of <1> to <5> which further contains a water-soluble polymer.

Thereby, the surface to be polished is protected from corrosion, and the occurrence of defects such as damage can be reduced.

The abrasive according to any one of <1> to <6> which further contains abrasive grains.

Thereby, when the film to be polished contains a layer other than the cobalt layer, the polishing rate of the layer other than the cobalt layer can be further increased.

(8) A method of polishing a substrate, wherein the abrasive film containing a cobalt element formed on at least one surface of the substrate is polished by using the polishing agent according to any one of the above items <1> to <7>, The excess containing the cobalt element is removed.

According to the polishing method of the present invention, the film to be polished containing the cobalt element can be polished while suppressing excessive corrosion while being high speed.

According to the present invention, it is possible to provide an abrasive which is excellent in the polishing rate of the cobalt layer and excellent in corrosion inhibition of the cobalt layer, and a polishing method of the substrate using the abrasive.

In this specification, the term "step" is used not only to refer to an independent step, but also to the extent that it is not clearly distinguishable from other steps, as long as the intended purpose of the step is achieved. Further, the numerical range indicated by "~" indicates a range in which the numerical values described before and after "~" are respectively included as the minimum value and the maximum value. Further, when a plurality of substances corresponding to the respective components are present in the polishing agent in the case of the content of each component in the polishing agent, unless otherwise specified, the total amount of the plurality of substances present in the polishing agent is referred to. .

Hereinafter, a suitable embodiment of the polishing method for polishing a layer containing a cobalt element (hereinafter also simply referred to as "abrasive") and a substrate will be described in detail.

[abrasive agent]

The polishing agent of the present invention contains a carboxylic acid derivative, a metal corrosion inhibitor and water, and has a pH of 4.0 or less. The carboxylic acid derivative comprises a compound selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and the following formula (I). And an alkyldicarboxylic acid compound represented by at least one of the group consisting of these salts and an acid anhydride.

HOOC-R-COOH. . . (I)

In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms.

<carboxylic acid derivative>

The abrasive of the present invention contains a carboxylic acid derivative (hereinafter also referred to as "specific a carboxylic acid derivative") which is selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and a dicarboxylic acid compound represented by the above formula (I) (hereinafter referred to as "specific dicarboxylic acid" At least one of a group consisting of an acid compound") and a salt and an acid anhydride. The above specific carboxylic acid derivatives may be used alone or in combination of two or more. By selecting the above specific carboxylic acid derivative among a myriad of carboxylic acid and carboxylic acid derivatives, a good polishing rate for the cobalt layer can be maintained, and the etching rate is moderately controlled, and corrosion is suppressed, thereby obtaining Good abrasive surface. That is, it is more convenient to suppress the etching rate of the cobalt layer under more severe conditions (for example, 50 ° C), and excellent corrosion inhibition can be achieved. Here, the corrosion suppression property is excellent, and it is included in the surface to be polished to effectively suppress the etching of the cobalt layer or the occurrence of cracks in the wiring layer.

Although the reason why such an effect can be obtained is not clear, the inventors presume the following. In other words, it is considered that the specific carboxylic acid derivative has an effect of, for example, functioning as a metal dissolving agent and improving the polishing rate of the cobalt layer. It is presumed that the above specific carboxylic acid derivative also has the following function: two carboxyl groups are chelated with cobalt atoms to form a cyclic structure, thereby forming a stable complex state, thereby controlling the etching rate and suppressing corrosion in the surface to be polished. . Furthermore, it is also possible that the metal corrosion inhibitor described later also contributes to the formation of the stable complex state.

The specific carboxylic acid derivative is preferably selected from the group consisting of a specific dicarboxylic acid compound, a salt thereof, and an acid anhydride thereof, from the viewpoints of the polishing rate of the cobalt layer, the controllability of the etching rate, and the corrosion inhibition property. In the group. It is sometimes difficult to balance the cobalt layer with an acidic compound other than the above specific carboxylic acid derivative. Good grinding speed and inhibition of the etching speed of the cobalt layer. The reason for this is considered to be that it is important to form a stable complex state as described above, and the three-dimensional structure of the acidic compound becomes an important factor. Further, even if the above-mentioned specific carboxylic acid derivative is contained, if an acidic compound other than the above is contained, the etching rate of the cobalt layer may be remarkably increased. The reason for this is considered to be that the etching effect of the other acidic compound on the cobalt layer is preferred over the formation of the complex state as described above.

In a first aspect of the abrasive according to the present invention, the carboxylic acid derivative comprises a dicarboxylic acid compound selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and the above formula (I), and a salt thereof. At least one of the groups consisting of anhydrides. However, the above carboxylic acid derivative may contain other carboxylic acid derivatives in a range which does not significantly impair the effects of the present invention, and the other carboxylic acid derivative is selected from the group consisting of phthalic acid compounds, isophthalic acid compounds, and the like. At least one of a group consisting of a dicarboxylic acid compound other than the dicarboxylic acid compound represented by the formula (I), a salt thereof, and an acid anhydride thereof. That is, the carboxylic acid derivative is substantially composed of a specific carboxylic acid derivative selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and the above formula (I). At least one of a group consisting of a carboxylic acid compound and a salt and an acid anhydride thereof. The term "substantially" as used herein means a range which does not significantly impair the effects of the present invention, and specifically means that the content of the other carboxylic acid derivative is 10% by mass or less based on the total mass of the specific carboxylic acid derivative. . Further, the content of the other carboxylic acid derivative is preferably 5% by mass or less, and more preferably 1% by mass or less based on the total mass of the specific carboxylic acid derivative.

In the same aspect, in the second aspect of the abrasive of the present invention, the carboxylic acid derivative contains a dicarboxylic acid selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and the above formula (I). At least one of a group consisting of an acid compound and a salt and an acid anhydride thereof, and an etching rate of cobalt at 50 ° C for the cobalt is 10.0 nm/min or less. In the second aspect, the carboxylic acid derivative may also contain other carboxylic acid derivatives, but the etching rate of cobalt in the 50 ° C abrasive must not exceed 10.0 nm / min, and the other carboxylic acid derivatives are selected from At least one of a group consisting of a phthalic acid compound, an isophthalic acid compound, and a dicarboxylic acid compound other than the dicarboxylic acid compound represented by the above formula (I), a salt thereof, and an acid anhydride thereof. The preferred range of the content of the above other carboxylic acid derivative is the same as that of the first aspect described above.

The etching rate of cobalt at 50 ° C can be measured as follows. In other words, a 20 mm square wafer (evaluation wafer) having a cobalt layer having a thickness of 0.3 μm formed on a tantalum substrate can be prepared, and the evaluation wafer can be placed in a beaker containing 50 g of a polishing agent at a constant temperature of 50 ° C. The film was immersed in the bath for 1 minute, and the film thickness of the cobalt layer before and after the immersion was measured, thereby (in the film thickness of the cobalt layer before immersion - the film thickness of the cobalt layer after immersion) / 1 minute [nm / min] Find out.

In the second aspect of the polishing agent of the present invention, the etching rate is 10.0 nm/min or less, and from the viewpoint of further improving the corrosion inhibiting property, it is preferably 9.0 nm/min or less, more preferably 8.0 nm/min. the following.

Further, in the first aspect of the abrasive of the present invention, the etching rate is preferably 10.0 from the viewpoint of further improving the corrosion inhibiting property. The ratio of nm/min or less is more preferably 9.0 nm/min or less, and further preferably 8.0 nm/min or less.

Among the above specific dicarboxylic acid compounds, the phthalic acid compound contains phthalic acid (benzene-1,2-dicarboxylic acid) and a phthalic acid derivative having one or more substituents on the benzene ring. At least one. Examples of the substituent include a methyl group, an amine group, a nitro group and the like. Among them, at least one of a nitro group and a methyl group is preferred, and a nitro group is more preferred.

Specific examples of the above phthalic acid compound include alkylphthalic acid such as phthalic acid, 3-methylphthalic acid or 4-methylphthalic acid; 3-aminophthalic acid, 4 - Aminophthalic acid such as aminophthalic acid; nitrophthalic acid such as 3-nitrophthalic acid or 4-nitrophthalic acid; Among them, preferred is a phthalic acid compound having a nitro group as a substituent (nitrophthalic acid), more preferably at least one of 3-nitrophthalic acid and 4-nitrophthalic acid. Particularly preferred is 3-nitrophthalic acid. The above phthalic acid compound can also be used in the form of an acid anhydride, and can also be used in the form of a salt.

The isophthalic acid compound contains at least one of isophthalic acid (benzene-1,3-dicarboxylic acid) and an isophthalic acid derivative having one or more substituents on the benzene ring. Examples of the substituent include a nitro group, a methyl group, an amine group, and a hydroxyl group. Among them, a nitro group is preferred.

Specific examples of the above isophthalic acid compound include isophthalic acid and 5-nitroisophthalic acid. The above isophthalic acid compound can also be used in the form of a salt.

The alkyl dicarboxylic acid compound represented by the above formula (I) is only required to have The alkyl dicarboxylic acid compound having an alkyl group having 4 to 10 carbon atoms may be used. Further, the carbon number of the above carbon number alkyl group and the carbon atom contained in the carboxylic acid group are not counted as the above carbon number. The alkylene group may be in the form of a ring, a linear chain or a branched chain. Among them, it is preferably linear. The carbon number is preferably from 4 to 8, more preferably from 4 to 6, from the viewpoints of the polishing rate of the cobalt layer, the controllability of the etching rate, and the corrosion inhibition.

Specific examples of the alkyl dicarboxylic acid having an alkylene group having 4 to 10 carbon atoms include adipic acid, pimelic acid, suberic acid, sebacic acid and the like. Among them, adipic acid and pimelic acid are preferred, and pimelic acid is more preferred.

The content of the carboxylic acid derivative is preferably in the range of 0.001% by mass to 10% by mass based on the total mass of the polishing agent. By adjusting the content of the carboxylic acid derivative within the above range, a layer other than the cobalt layer provided in the vicinity of the cobalt layer (for example, a wiring such as copper as the conductive material layer 5 shown in FIG. 2(a)) can be obtained. Good polishing speed with metal or barrier metal layer 3, etc.).

The content of the carboxylic acid derivative is more preferably 0.01% by mass or more, further preferably 0.03% by mass or more, and particularly preferably 0.05% by mass or more, from the viewpoint of the polishing rate. In addition, the content of the dicarboxylic acid is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 1.0% by mass or less, from the viewpoint of the etching inhibitory effect and the corrosion inhibiting property of the cobalt layer. The content is preferably 0.7% by mass or less, and more preferably 0.5% by mass or less.

The polishing agent preferably contains, as a carboxylic acid derivative, at least one compound selected from the group consisting of alkyl phthalic acid and an amine group, in an amount of 0.01% by mass or more, from the viewpoint of the polishing rate. Phthalate, Nitrophthalic acid, isophthalic acid, 5-nitroisophthalic acid, and alkyl dicarboxyl represented by the formula (I) and wherein R is a linear alkyl group having 4 to 8 carbon atoms An acid compound, and a salt of these and an acid anhydride.

Further, from the viewpoint of suppressing the etching effect on the cobalt layer, the polishing agent preferably contains at least one compound selected from the group consisting of 5.0% by mass or less as a carboxylic acid derivative, and the above group is an alkyl group. Phthalic acid, aminophthalic acid, nitrophthalic acid, isophthalic acid, 5-nitroisophthalic acid, and represented by the formula (I) and R is a carbon number of 4-8 A linear alkylene alkyl dicarboxylic acid compound, and a salt and an acid anhydride thereof.

<Metal corrosion inhibitor>

The metal corrosion inhibitor contained in the abrasive of the present invention is not particularly limited, and a conventionally known metal corrosion inhibitor can be arbitrarily used as a compound having an anticorrosive effect on a metal. Specifically, at least one selected from the group consisting of a triazole compound, a pyridine compound, a pyrazole compound, a pyrimidine compound, an imidazole compound, an anthraquinone compound, a thiazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine can be used. The term "compound" as used herein refers to a compound of a compound having the skeleton. For example, a triazole compound means a compound having a triazole skeleton.

Examples of the triazole compound include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, and 1-hydroxybenzene. And triazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxy-1H-benzotriazole, 4-carboxyl -1H-benzotriazole methyl ester (1H-benzotriazole-4-carboxylic acid methyl ester), 4-carboxy-1H-benzotriazol butyl ester (1H-benzotriazole-4-carboxylic acid butyl) Ester), 4-carboxy-1H-benzotriazol octyl ester (1H-benzoate) Triazol-4-carboxylic acid octyl ester), 5-hexylbenzotriazole, (1,2,3-benzotriazolyl-1-methyl) (1,2,4-triazolyl-1-yl) (2-ethylhexyl)amine, tolyltriazole, naphthotriazole, bis[(1-benzotriazolyl)methyl]phosphonic acid, 3H-1,2,3-triazolo[4 , 5-b]pyridin-3-ol, 1H-1,2,3-triazolo[4,5-b]pyridine, 1-ethylindenyl-1H-1,2,3-triazolo[4 , 5-b]pyridine, 3-hydroxypyridine, 1,2,4-triazolo[1,5-a]pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimidine[ 1,2-a]pyrimidine, 2-methyl-5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7 -diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro-[1,2 , 4] triazolo[1,5-a]pyrimidine and the like. Further, in the case where a triazole skeleton and a skeleton other than the above are contained in one molecule, they are classified into a triazole compound.

Examples of the pyridine compound include 8-hydroxyquinoline, propionamide, 2-nitropyridin-3-ol, pyridoxamine, nicotinamide, isopropylidene, isonicotinic acid, benzo[ f] quinoline, 2,5-pyridinedicarboxylic acid, 4-styrylpyridine, neonicotinoid, 4-nitropyridine-1-oxide, pyridine-3-acetic acid ethyl ester, quinoline, 2-B Pyridine, quinolinic acid, arecoline, citrazinic acid, pyridine-3-methanol, 2-methyl-5-ethylpyridine, 2-fluoropyridine, pentafluoropyridine, 6-A Pyridin-3-ol, pyridin-2-acetate, and the like.

Examples of the pyrazole compound include pyrazole, 1-allyl-3,5-dimethylpyrazole, 3,5-di(2-pyridyl)pyrazole, and 3,5-diisopropylpyrazole. , 3,5-Dimethyl-1-hydroxymethylpyrazole, 3,5-dimethyl-1-phenylpyrazole, 3,5-dimethylpyrazole, 3-amino-5-hydroxyl Pyrazole, 4-methylpyrazole, N-methylpyrazole, 3-aminopyrazole, 3-aminopyrazole, and the like.

Pyrimidine compounds can be exemplified by pyrimidine, 1,3-diphenyl-pyrimidine-2, 4, 6-three Ketone, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxypyrimidine, 2,4-di Aminopyrimidine, 2-acetamimidin, 2-aminopyrimidine, 4-aminopyrazolo[3,4-d]pyrimidine, and the like.

Examples of the imidazole compound include 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, 1-butylimidazole, 1-ethylimidazole, 1-methylimidazole, benzimidazole, and the like.

Examples of the ruthenium compound include 1,1,3,3-tetramethylguanidine, 1,2,3-triphenylphosphonium, 1,3-di-o-tolylhydrazine, and 1,3-diphenylphosphonium.

Examples of the thiazole compound include 2-mercaptobenzothiazole and 2,4-dimethylthiazole.

Examples of the tetrazole compound include tetrazole, 5-methyltetrazole, 5-amino-1H-tetrazole, and 1-(2-dimethylaminoethyl)-5-mercaptotetrazole.

Examples of the triazine compound include 3,4-dihydro-3-hydroxy-4-oxa-1,2,4-triazine and the like.

The above metal corrosion inhibitors may be used alone or in combination of two or more. In view of obtaining a good polishing rate for the film to be polished containing cobalt element, the content of the metal corrosion inhibitor is preferably 0.001% by mass to 10% by mass based on the total mass of the polishing agent. From the same viewpoint, the content of the metal corrosion inhibitor is preferably 0.01% by mass or more, and more preferably 0.02% by mass or more. In addition, from the same viewpoint, the content of the metal corrosion inhibitor is preferably 5.0% by mass or less, and more preferably 0.5% by mass.

By combining the above metal corrosion inhibitor with the above carboxylic acid derivative, the etching rate of the cobalt layer is remarkably suppressed even under severe temperature conditions (for example, 50 ° C), and the cobalt layer is ground at a moderate speed to suppress the cobalt layer. corrosion. The reason for this is considered to be that, for example, the metal corrosion inhibitor exhibits a function as an excellent complex forming agent and a film protective agent in the coexistence with the specific dicarboxylic acid compound.

In this regard, the metal corrosion inhibitor is preferably at least one selected from the group consisting of a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine. More preferably, it is selected from 3H-1,2,3-triazolo[4,5-b]pyridin-3-ol, 1-hydroxybenzotriazole, 1H-1,2,3-triazolo[ 4,5-b] triazole compound such as pyridine or benzotriazole, 3-hydroxypyridine, benzimidazole, 5-amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxo At least one of the group consisting of hetero-1,2,4-triazine and hexamethylenetetramine.

The ratio of the carboxylic acid derivative to the metal corrosion inhibitor (carboxylic acid derivative/metal corrosion inhibitor) in the above abrasive is preferably 10/1 to 1 in terms of mass ratio from the viewpoint of controlling the etching rate and the polishing rate well. The range of /5 is more preferably in the range of 7/1 to 1/5, and thus preferably in the range of 5/1 to 1/5, and particularly preferably in the range of 5/1 to 1/1.

Further, from the viewpoint of controlling the etching rate and the polishing rate well, the polishing agent is preferably a carboxylic acid derivative selected from the group consisting of a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and a hexamethylene group. The ratio of at least one metal corrosion inhibitor (carboxylic acid derivative/metal corrosion inhibitor) in the group consisting of tetramines is 10/1 to 1/5, More preferably, the ratio of the above carboxylic acid derivative to at least one metal corrosion inhibitor selected from the group consisting of a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine ( The carboxylic acid derivative/metal corrosion inhibitor) is 5/1 to 1/5, and further preferably the above carboxylic acid derivative is selected from 3H-1,2,3-triazolo[4,5-b]pyridine-3. - a triazole compound such as an alcohol, 1-hydroxybenzotriazole, 1H-1,2,3-triazolo[4,5-b]pyridine, benzotriazole, and 3-hydroxypyridine, benzimidazole, 5 - at least one metal of the group consisting of amino-1H-tetrazole, 3,4-dihydro-3-hydroxy-4-oxa-1,2,4-triazine and hexamethylenetetramine The ratio of the corrosion inhibitor (carboxylic acid derivative/metal corrosion inhibitor) is 5/1 to 1/1.

<oxidant>

Preferably, the above abrasive further contains at least one oxidizing agent. By further containing an oxidizing agent, the polishing rate of the layer other than the cobalt layer can be further increased. The above oxidizing agent is not particularly limited and may be appropriately selected from oxidizing agents which are usually used. Specific examples thereof include hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, and ozone water. Among them, hydrogen peroxide is preferred. These metal oxidizing agents may be used alone or in combination of two or more.

When the abrasive contains an oxidizing agent, the content of the metal oxidizing agent is preferably set to 0.01% by mass to 50% by mass based on the total mass of the abrasive. The content is preferably 0.02% by mass or more, and more preferably 0.05% by mass or more, from the viewpoint of preventing oxidation of the metal from being insufficient and reducing the polishing rate. In addition, it is more preferably 30% by mass or less, and still more preferably 15% by mass or less from the viewpoint of preventing roughening of the surface to be polished.

<organic solvent>

The above abrasive may further contain an organic solvent. By adding an organic solvent, the wettability of the layer other than the cobalt layer provided in the vicinity of the cobalt layer can be improved, and the polishing rate can be further increased. The above organic solvent is not particularly limited, and is preferably water-soluble. The term "water solubility" as used herein is defined as dissolving 0.1 g or more with respect to 100 g of water at 25 °C.

Examples of the organic solvent include carbonate solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactone solvents such as butyrolactone and propiolactone; a glycol solvent such as alcohol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol or tripropylene glycol; tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl ether Ether solvent such as acid ester, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, isopropanol, 3-methoxy Alcohol solvent such as benzyl-3-methyl-1-butanol; ketone solvent such as acetone or methyl ethyl ketone; dimethylformamide, N-methylpyrrolidone, ethyl acetate, ethyl lactate, and ring Other organic solvents such as Ding Wei.

Further, the organic solvent may also be a derivative of a diol solvent. For example, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, Propylene glycol monoethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethyl Glycol monopropyl ether, tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl Glycol monoether solvent such as ether; ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethyl Diol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, three Ethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, triethylene glycol dipropyl ether, tripropylene glycol dipropyl ether A glycol ether solvent such as ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether or tripropylene glycol dibutyl ether.

Among them, at least one selected from the group consisting of a glycol solvent, a derivative of a glycol solvent, an alcohol solvent, and a carbonate solvent is preferred, and more preferably at least one selected from the group consisting of alcohol solvents. These organic solvents may be used alone or in combination of two or more.

When the abrasive contains an organic solvent, the content of the organic solvent is preferably from 0.1% by mass to 95% by mass based on the total mass of the abrasive. The content of the organic solvent is preferably 0.2% by mass or more, and more preferably 0.5% by mass or more, from the viewpoint of preventing the wettability of the polishing agent on the substrate from being lowered. In addition, it is more preferably 50% by mass or less, and still more preferably 10% by mass or less, in terms of ease of preparation, use, and waste treatment of the polishing agent.

<Water-soluble polymer>

The above abrasive preferably contains at least one water soluble polymer. Thereby, the suppression of the corrosion effect, the protection of the film surface, the reduction of the occurrence of defects, and the like can be more effectively achieved. The term "water solubility" as used herein is defined as dissolving 0.1 g or more with respect to 100 g of water at 25 °C.

The water-soluble polymer may be exemplified by water having a carboxylic acid group or a carboxylate group. Soluble polymer, etc. Examples of such a water-soluble polymer include a homopolymer of a monomer having a carboxylic acid group such as acrylic acid, methacrylic acid or maleic acid; and a portion of the carboxylic acid group of the polymer becomes a carboxylate group such as an ammonium salt. Polymer, etc. Further, a copolymer of a monomer having a carboxylic acid group, a monomer having a carboxylate group, and a derivative such as an alkyl ester of a carboxylic acid is also preferred. Specific examples of the water-soluble polymer include polyacrylic acid, a polymer obtained by replacing at least a part of a carboxylic acid group of polyacrylic acid with an ammonium carboxylate group (hereinafter referred to as "polyacrylic acid ammonium salt").

Further, examples of the water-soluble polymer other than the above include polysaccharides such as alginic acid, pectic acid, carboxymethyl cellulose, agar, carterol, and pullulan; polyascorbic acid and polyglutamic acid; Polycarboxylic acid, polymalic acid, polyamic acid, polyammonium ammonium salt, polyamidosodium salt, polyglycolic acid and other polycarboxylic acids and salts thereof; polyvinyl alcohol, polyvinylpyrrolidone And a vinyl polymer such as polyacrylaldehyde.

When the substrate to be polished is a substrate for a semiconductor integrated circuit or the like, the water-soluble polymer is preferably an acid group-based polymerization from the viewpoint of avoiding contamination by the alkali metal, alkaline earth metal, or halide. Or its ammonium salt. However, the case where the substrate to be polished is a glass substrate or the like is not limited thereto.

Among the above water-soluble polymers, it is preferably selected from water-soluble polymers having a carboxylic acid group or a carboxylate group, pectic acid, agar, polymalic acid, polypropylene decylamine, polyvinyl alcohol, and polyvinylpyrrole. a water-soluble polymer in a group consisting of ketones (including esters and salts in the case of esters, salts), more preferably a water-soluble polymer having a carboxylic acid group or a carboxylate group ( Including esters, salts), and thus preferably polyacrylic acid (including salts), especially polypropylene Ammonium salt. These water-soluble polymers may be used alone or in combination of two or more.

The weight average molecular weight of the water-soluble polymer is preferably from 500 to 1,000,000, more preferably from 1,000 to 500,000, further preferably from 2,000 to 200,000, and particularly preferably from 5,000 to 150,000.

The above weight average molecular weight can be measured, for example, by a value measured by a gel permeation chromatography (GPC) and converted to a standard polyacrylic acid according to the following method.

(condition)

Sample: 10 μL

Standard polyacrylic acid: manufactured by Hitachi Chemical Techno Service Co., Ltd., trade name: PMAA-32

Detector: manufactured by Hitachi, Ltd., Reactive Ion (RI)-monitor, trade name "L-3000"

Integrator: manufactured by Hitachi, Ltd., GPC integrator, trade name "D-2200"

Pump: manufactured by Hitachi, Ltd., trade name "L-6000"

Degassing device: manufactured by Showa Denko Co., Ltd., trade name "Shodex DEGAS"

Pipe column: manufactured by Hitachi Chemical Co., Ltd., and the product names "GL-R440", "GL-R430", and "GL-R420" are used in sequence.

Dissolved solution: tetrahydrofuran (THF)

Measuring temperature: 23 ° C

Flow rate: 1.75mL/min

Measurement time: 45 minutes

When the abrasive contains a water-soluble polymer, the content of the water-soluble polymer is preferably from 0.001% by mass to 10% by mass based on the total mass of the abrasive. In terms of ensuring good corrosion inhibition, it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.02% by mass or more. In addition, in terms of maintaining a sufficient polishing rate, it is preferably 10% by mass or less, more preferably 5.0% by mass or less, and still more preferably 1.0% by mass or less.

<abrasive grain>

Preferably, the abrasive comprises at least one abrasive particle. By containing the abrasive grains, the polishing rate of the layer other than the cobalt layer provided in the vicinity of the cobalt layer can be improved.

Examples of the main abrasive grains include inorganic abrasive particles such as cerium oxide, aluminum oxide, zirconium oxide, cerium oxide, titanium oxide, cerium oxide, and cerium carbide, and organic materials such as polystyrene, polyacrylic acid, and polyvinyl chloride. Particles, etc. Among these, inorganic abrasive particles selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, cerium oxide, titanium oxide, and cerium oxide are preferred, and are preferably selected from the group consisting of cerium oxide and aluminum oxide. Inorganic abrasive particles in the group consisting of.

In the inorganic abrasive particles selected from the group consisting of cerium oxide and aluminum oxide, the dispersion stability in the polishing agent is good, and the number of polishing damage (scratches) due to CMP is small. In other words, colloidal cerium oxide or colloidal alumina is preferred, and colloidal cerium oxide is more preferred. These abrasive grains may be used alone or in combination of two or more.

The average particle diameter of the abrasive grains is preferably from 10 nm to 100 nm, more preferably from 20 nm to 90 nm, even more preferably from 40 nm to 80 nm, in terms of obtaining a good polishing rate.

The average particle diameter of the abrasive grains is a value measured by a light diffraction scattering type particle size distribution meter (for example, trade name: COULTER N4SD manufactured by COULTER Electronics Co., Ltd.). The measurement conditions of Coulter were as follows: the measurement temperature was 20 ° C, the solvent refractive index was 1.333 (corresponding to water), the particle refractive index was set to unknown (Unknown), and the solvent viscosity was 1.005 mPa. s (equivalent to water), running time (Run Time) is 200 sec, laser incident angle is 90°, and Intensity (scattering intensity, equivalent to turbidity) is in the range of 5E+04~4E+05. When it is higher than 4E+05, it is measured after dilution with water.

When the abrasive contains abrasive grains, the content of the abrasive grains in the total mass of the abrasive is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and still more preferably 3.0% by mass to 5.0% by mass. By setting the content of the above abrasive grains within the above range, a good polishing rate can be obtained.

<water>

The water used in the present invention is not particularly limited, and pure water can be preferably used. The water may be formulated as long as it is the remainder of the constituent material of the polishing agent, and the content thereof is not particularly limited.

<Other>

Examples of other components which can be added to the polishing agent include colorants such as a surfactant, a dye such as Victoria Pure Blue, and a pigment such as phthalocyanine green.

The polishing agent has a pH of 4.0 or less. If the pH exceeds 4.0, Then, the polishing rate of the conductive material layer including the wiring metal and the cobalt layer is lowered. On the other hand, the pH is preferably 1.0 or more, and more preferably 2.0 or more, in terms of suppressing the corrosion of the wiring metal and the difficulty in handling due to the strong acidity.

The pH can be adjusted by the amount of the acidic compound added. Further, it may be adjusted by adding an alkaline compound such as ammonia, sodium hydroxide or tetramethylammonium hydroxide (TMAH).

The pH of the above-mentioned abrasive is measured by a pH meter (for example, Model F-51 manufactured by HORIBA, Ltd.). Standard buffer (phthalate pH buffer, pH 4.21 (25 ° C); neutral phosphate pH buffer, pH 6.86 (25 ° C); borate pH buffer, pH) After performing 3-point calibration for 9.04 (25 ° C), the electrode was placed in an abrasive, and the value which was stabilized after 3 minutes or more was measured.

The polishing agent is stored in the form of an abrasive (storage liquid) containing a carboxylic acid derivative, a metal corrosion inhibitor, and water, and may be used by appropriately mixing the polishing agent with other constituent materials and water during polishing. In addition, it can also be stored and used in a state in which an carboxylic acid derivative, a metal corrosion inhibitor, and an abrasive having other constituent materials are appropriately blended in water.

The above abrasive can be applied to the formation of a wiring layer in a semiconductor device. The film to be polished to be polished may include at least a portion containing a cobalt element (hereinafter referred to as a "cobalt portion"), and may further include a conductive material, a barrier metal or an insulator provided in the vicinity of the cobalt portion.

That is, another aspect of the present invention is that the pair of the following abrasives contain cobalt When the layer is polished, the polishing agent contains a carboxylic acid derivative, a metal corrosion inhibitor, and water, and has a pH of 4 or less, and the carboxylic acid derivative is selected from the group consisting of a phthalic acid compound and an isophthalic acid compound. At least one of the group consisting of the alkyl dicarboxylic acid compound represented by the following formula (I) and a salt and an acid anhydride thereof.

HOOC-R-COOH. . . (I)

In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms.

Further, another aspect of the present invention is the use of the following polishing agent for polishing a layer containing a cobalt element, wherein the polishing agent contains at least one carboxylic acid derivative, a metal corrosion inhibitor, and water, and has a pH of 4.0 or less. The etching rate of cobalt at 50 ° C is 10.0 nm / min or less, and the at least one carboxylic acid derivative is selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, and an alkane represented by the following formula (I) A group consisting of a biscarboxylic acid compound and a salt and an acid anhydride thereof.

HOOC-R-COOH. . . (I)

In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms.

[Method of Grinding Substrate]

The polishing method of the substrate of the present invention is a polishing method in which a polishing film containing a cobalt element formed on at least one surface of a substrate is polished using the above-described polishing agent, and an excess portion containing a cobalt element is removed. more detail In the polishing method, the abrasive is applied to the polishing film containing the cobalt element formed on at least one surface of the substrate and the polishing cloth on the polishing plate, and the polishing agent is supplied while being polished. The surface of the substrate on the surface side of the film is pressed against the polishing cloth, and the substrate is moved relative to the polishing platen to remove at least a part of the film to be polished.

Hereinafter, a series of steps of forming a wiring layer in a semiconductor device using the polishing method of the substrate of the present invention will be described with reference to FIG. However, the use of the abrasive of the present invention is not limited to the following steps.

As shown in FIG. 2( a ), the substrate 10 before polishing has an insulator 2 having a concave portion of a predetermined pattern on the substrate 1 , and a barrier metal layer 3 covering the insulator 2 along the surface of the insulator 2 . And a cobalt layer 4 covering the barrier metal layer 3, and a conductive material layer 5 is formed on the cobalt layer 4.

Examples of the insulator 2 include a lanthanum insulator, an organic polymer insulator, and the like. Examples of the lanthanide insulator include cerium oxide, fluorosilicate glass, organic bismuth silicate glass obtained by using trimethyl decane or dimethoxy dimethyl decane as a starting material, bismuth oxynitride, and hydrogenated hydrazine. A cerium oxide-based insulator such as a semi-oxane or a tantalum carbide or tantalum nitride. Further, examples of the organic polymer-based insulator include wholly aromatic low dielectric constant insulators. Among these insulators, particularly preferred is cerium oxide.

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

The barrier metal layer 3 is for preventing the conductive material from expanding into the insulator 2 It is formed in order to improve the adhesion between the insulator 2 and the conductive material layer 5. Examples of the barrier metal used in the barrier metal layer 3 include germanium compounds such as germanium, tantalum nitride, and hafnium alloy, titanium compounds such as titanium, titanium nitride, and titanium alloy, and tungsten compounds such as tungsten, tungsten nitride, and tungsten alloy.钌 钌 钌 compounds, etc. The barrier metal layer 3 may be a single layer structure including one of the metals, or may have a laminate structure of two or more types. The barrier metal layer 3 is formed by vapor deposition, chemical vapor deposition (CVD), or the like. Further, only the cobalt layer 4 may be provided as the barrier metal layer 3.

Examples of the cobalt used in the cobalt layer 4 include cobalt, a cobalt alloy, an oxide of cobalt, an oxide of a cobalt alloy, and the like. The cobalt layer is formed by a known sputtering method or the like.

Examples of the conductive material used in the conductive material layer 5 include a metal containing copper as a main component such as copper, a copper alloy, an oxide of copper, or an oxide of a copper alloy, a tungsten metal such as tungsten or a tungsten alloy, silver, gold, or the like. Precious metals, etc. Among them, a metal containing copper as a main component such as an oxide of copper, a copper alloy, copper, or an oxide of a copper alloy is preferable. The conductive material layer 5 is formed by a known sputtering method, a plating method, or the like.

The thickness of the insulator 2 is preferably about 0.01 μm to 2.0 μm, the thickness of the barrier metal layer 3 is preferably about 0.01 μm to 2.5 μm, and the thickness of the cobalt layer 4 is preferably about 0.01 μm to 2.5 μm. The thickness of 5 is preferably about 0.01 μm to 2.5 μm.

In the first polishing step of polishing the conductive material layer 5 from the state shown in FIG. 2( a ) to the state shown in FIG. 2( b ), for example, the conductive material layer 5 / cobalt layer 4 is used. Grinding speed is greater than that of a sufficiently large abrasive for the conductive material, and by CMP on the surface of the substrate 10 before polishing The conductive material layer 5 is polished. Thereby, the cobalt layer 4 of the convex portion on the substrate is exposed on the surface, and the substrate 20 having the conductor pattern in which the conductive material layer 5 remains in the concave portion is obtained. For the polishing agent for the conductive material having a sufficiently large polishing rate of the conductive material layer 5/cobalt layer 4, for example, an abrasive described in the specification of Japanese Patent No. 3337464 can be used. In the first polishing step, a part of the cobalt layer 4 of the convex portion may be polished together with the conductive material layer 5.

Then, in the second polishing step, the conductor pattern obtained by the first polishing step is used as the film to be polished for the second polishing step, and is polished using the polishing agent of the present invention.

In the second polishing step, while the substrate 20 is pressed against the polishing cloth of the polishing platen, the polishing platen of the present invention is supplied between the polishing cloth and the substrate, and the polishing platen and the substrate 20 are relatively moved. Thereby, the cobalt layer 4 exposed by the first polishing step is polished.

As the polishing apparatus, a general polishing apparatus having a holder that holds the substrate to be polished, a polishing plate, and a motor having a variable rotational speed, and a polishing cloth attached thereto can be used. As the polishing cloth, a general non-woven fabric, a foamed polyurethane, a porous fluororesin or the like can be used, and it is not particularly limited.

The polishing conditions are not particularly limited, and the rotation speed of the polishing platen is preferably a low rotation of 200 rpm or less to prevent the substrate from flying out. The pressing force of pressing the substrate having the film to be polished on the polishing cloth is preferably from 1 kPa to 100 kPa, and more preferably from 5 kPa to 50 kPa in order to satisfy the polishing in-plane uniformity and the flatness of the pattern.

During the polishing, the abrasive of the present invention is continuously supplied between the polishing cloth and the film to be polished by a pump or the like. The amount of supply is not limited, and it is preferred that the surface of the polishing cloth is always covered with an abrasive. After the polishing is completed, the substrate is preferably sufficiently washed in running water, and then the water droplets adhering to the substrate are dried by using a spin dryer or the like.

In the second polishing step, at least the exposed cobalt layer 4 is polished to remove excess cobalt. In the second polishing step, the cobalt layer 4 may be polished, the barrier metal layer 3 is exposed, the polishing is finished, and the barrier metal layer 3 is polished using an abrasive for polishing the barrier metal layer. Alternatively, as shown in FIG. 2(b) to FIG. 2(c), the cobalt layer 4 may be continuously polished from the cobalt layer 4 to the barrier metal layer 3 in the second polishing step. Further, the conductive material layer 5 embedded in the concave portion may be polished together with the cobalt layer 4 and the barrier metal layer 3.

When the substrate 30 having the desired pattern is obtained, the polishing is completed, and the insulator 2 of the substrate 30 under the barrier metal layer 3 of the convex portion is entirely exposed, and the conductive material layer 5 serving as the wiring layer remains in the recess. The cross section of the barrier metal layer 3 and the cobalt layer 4 is exposed at the boundary between the convex portion and the concave portion.

In order to ensure more excellent flatness at the end of polishing, it is also possible to further perform polishing as shown in FIG. 3 (for example, in the case where the time until the desired pattern is obtained in the second polishing step is 100 seconds, The case of additional grinding for 50 seconds other than the 100-second polishing is referred to as over-polishing by 50%). In the case of over-grinding, a portion of the insulator 2 is also removed by grinding.

After the second layer of the insulator and the metal wiring are further formed on the metal wiring formed in this manner, polishing is performed to make the entire surface of the semiconductor substrate flat Sliding face. By repeating this step a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

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

[Example]

Hereinafter, the invention will be specifically described by way of examples, but the invention is not limited to the examples.

<Evaluation of etching amount of cobalt>

[Examples and Comparative Examples]

(Method of making abrasive)

In the container, the metal corrosion inhibitors and carboxylic acid derivatives shown in Tables 1 and 2 were added to the final amount of the polishing agent as shown in Table 1, and added to the final polishing agent to become 0.02. The amount of the mass% of the polyacrylic acid ammonium salt as a water-soluble polymer (manufactured by Hitachi Chemical Co., Ltd., molecular weight: 8,000), and the amount of 1.4% by mass in the final polishing agent as a 3-methoxy group as an organic solvent -3-methyl-1-butanol was poured into ultrapure water, stirred and mixed to dissolve all the components.

Then, a colloidal cerium oxide (manufactured by Fuso Chemical Industry Co., Ltd., particle diameter: 60 nm) as a cerium oxide particle was added as an abrasive granule in an amount of 4.0% by mass based on the total mass of the prepared slurry. , again, inject ultrapure water to obtain a slurry. 30% by mass of hydrogen peroxide water was added so as to be 0.2% by mass in the total mass of the obtained slurry to obtain various abrasives.

The pH values of the obtained abrasives were measured and shown in Tables 1 and 2.

(Evaluation of the amount of etching of cobalt)

A blanket substrate (a) having a cobalt layer having a thickness of 300 nm was formed on a ruthenium substrate of 8 Å by a CVD method. The blanket substrate (a) was cut out into a 20 mm square wafer to prepare a wafer (b) for evaluation.

The evaluation wafer (b) was placed in a beaker containing 50 g of each of the above-mentioned polishing agents, and immersed in a thermostat at 50 ° C for 1 minute. The immersed evaluation wafer (b) was taken out, washed thoroughly with pure water, and then nitrogen gas was sprayed to dry the water on the wafer. The electric resistance of the wafer (b) for evaluation after drying was measured by a resistivity meter, and converted into the film thickness of the cobalt layer after immersion by the following formula (1).

A calibration curve is obtained based on the information of the resistance values corresponding to the respective film thicknesses of the blanket substrate (a), and the film thickness of the cobalt layer is obtained by the following formula (1).

The film thickness of the cobalt layer after immersion [nm] = 104.5 × (resistance value of the wafer (b) for evaluation [mΩ] / 1000) - ^0.893 . . . (1)

Further, the etching rate of the cobalt layer is determined by the following formula (2) from the film thickness of the obtained cobalt layer after immersion and the thickness of the cobalt layer before immersion.

Cobalt layer etching rate (Co-ER) [nm / min] = (film thickness of the cobalt layer before immersion [nm] - film thickness of the cobalt layer after immersion [nm]) / 1min. . . (2)

The etching rate for the cobalt layer was determined for each of the polishing agents obtained above. The results are shown in Tables 1 and 2. Further, in Tables 1 and 2, "-" in the column of the carboxylic acid derivative and the metal corrosion inhibitor indicates that it is not formulated.

(Evaluation of the grinding speed of cobalt)

In addition, the polishing rate (Co-RR) [nm/min] at the time of polishing the above-mentioned blanket substrate (a) was evaluated using the respective polishing agents obtained above. The results are shown together in Tables 1 and 2. Further, in some comparative examples, since the etching rate was too fast, the evaluation of the polishing rate was omitted, and it was represented by "-".

<grinding conditions>

Abrasive cloth: IC1000

Grinding pressure: 10.3 kPa (1.5 psi)

Speed: fixed plate / grinding head = 93/87rpm

Supply of abrasive: 200mL/min

Grinding time: 0.5 minutes

It is clear from Tables 1 and 2 that in Examples 1 to 13, by simultaneously containing a specific dicarboxylic acid and a metal corrosion inhibitor, the etching rate of cobalt can be remarkably suppressed even at 50 ° C. The cobalt layer is ground at a suitable speed. From the above, in the polishing agent of the present invention containing the carboxylic acid derivative, the specific dicarboxylic acid compound functions as a complex forming agent and an anticorrosive agent. In other words, according to the polishing agent of the present invention, when a layer containing a cobalt element is polished, it is possible to effectively suppress excessive etching of a layer containing a cobalt element or cracks caused by corrosion at a good polishing rate. Grinding.

1‧‧‧矽 substrate

2‧‧‧Insulator

3‧‧‧Barrier metal layer

4‧‧‧Cobalt layer

5‧‧‧ Conductive material layer (metal for wiring)

10, 20, 30‧‧‧ substrates

1 is a schematic cross-sectional view showing a wiring forming process in a prior damascene process.

2 is a schematic cross-sectional view showing a wiring forming process in a damascene process using a cobalt layer.

3 is a cross-sectional view showing an example of a substrate polished by the polishing method of the present invention.

1‧‧‧矽 substrate

2‧‧‧Insulator

3‧‧‧Barrier metal layer

4‧‧‧Cobalt layer

5‧‧‧ Conductive material layer (metal for wiring)

10, 20, 30‧‧‧ substrates

Claims (31)

An abrasive for polishing a layer containing a cobalt element, comprising at least one carboxylic acid derivative, a metal corrosion inhibitor, and water, and having a pH of 4.0 or less, and an etching rate of cobalt of 10.0 nm at 50 ° C /min or less, the at least one carboxylic acid derivative is selected from the group consisting of a phthalic acid compound, an isophthalic acid compound, an alkyl dicarboxylic acid compound represented by the following formula (I), and a salt and an acid anhydride thereof. In the group, HOOC-R-COOH. . . (I) In the above formula (I), R represents an alkylene group having 4 to 10 carbon atoms. The abrasive according to claim 1, wherein the carboxylic acid derivative comprises a phthalic acid derivative selected from the group consisting of phthalic acid and having at least one substituent on the benzene ring, and isophthalic acid. a group consisting of an isophthalic acid derivative having one or more substituents on a benzene ring and an alkyl dicarboxylic acid compound having an alkylene group having a carbon number of 4 to 8 represented by the above formula (I) At least one of the groups. The abrasive according to claim 1, wherein the carboxylic acid derivative comprises one selected from the group consisting of phthalic acid and having a group selected from a methyl group, an amine group and a nitro group on a benzene ring. a phthalic acid derivative having at least one substituent, isophthalic acid, or a benzene ring having at least one substituent selected from the group consisting of a nitro group, a methyl group, an amine group, and a hydroxyl group a phthalic acid derivative and a carbon number represented by the above formula (I) At least one of the group consisting of 4 to 8 alkylene-alkyl dicarboxylic acid compounds. The abrasive according to claim 1, wherein the carboxylic acid derivative comprises a phthalic acid selected from the group consisting of phthalic acid, alkyl phthalic acid, amino phthalic acid, nitrophthalic acid, and isophthalic acid. At least one of the group consisting of dicarboxylic acid, nitroisophthalic acid, adipic acid, pimelic acid, suberic acid, and sebacic acid. The abrasive according to claim 1, wherein the content of the carboxylic acid derivative is from 0.001% by mass to 10% by mass based on the total mass of the abrasive. The abrasive according to claim 1, which comprises 0.01% by mass or more selected from the group consisting of alkylphthalic acid, aminophthalic acid, nitrophthalic acid, isophthalic acid, 5- a group consisting of nitroisophthalic acid, an alkyldicarboxylic acid compound represented by the formula (I) and having a linear alkyl group having 4 to 8 carbon atoms, and a salt and an acid anhydride thereof At least one of them is used as the above carboxylic acid derivative. The abrasive according to claim 1, which comprises 5.0% by mass or less selected from the group consisting of alkylphthalic acid, aminophthalic acid, nitrophthalic acid, isophthalic acid, 5- a group consisting of nitroisophthalic acid, an alkyldicarboxylic acid compound represented by the formula (I) and having a linear alkyl group having 4 to 8 carbon atoms, and a salt and an acid anhydride thereof At least one of them is used as the above carboxylic acid derivative. The abrasive according to claim 1, wherein the metal corrosion inhibitor comprises a compound selected from the group consisting of a triazole compound, a pyridine compound, and a pyrazole. At least one of a group consisting of a pyrimidine compound, an imidazole compound, an anthraquinone compound, a thiazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine. The abrasive according to claim 1, wherein the metal corrosion inhibitor comprises a group selected from the group consisting of a triazole compound, a pyridine compound, an imidazole compound, a tetrazole compound, a triazine compound, and hexamethylenetetramine. At least one of them. The abrasive according to claim 1, wherein the metal corrosion inhibitor comprises a compound having a triazole skeleton. The abrasive according to claim 10, wherein the compound having a triazole skeleton is selected from the group consisting of 1,2,3-triazole, 1,2,4-triazole, and 3-amino-1H-1. , 2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzo Triazole, 4-carboxy-1H-benzotriazole, 4-carboxy-1H-benzotriazole methyl ester (methyl 1H-benzotriazole-4-carboxylate), 4-carboxy-1H-benzoate Triazolyl ester (1H-benzotriazole-4-carboxylic acid butyl ester), 4-carboxy-1H-benzotriazol octyl ester (1H-benzotriazole-4-carboxylic acid octyl ester), 5-hexyl Benzotriazole, (1,2,3-benzotriazolyl-1-methyl)(1,2,4-triazolyl-1-methyl)(2-ethylhexyl)amine, toluene III Azole, naphthotriazole, bis[(1-benzotriazolyl)methyl]phosphonic acid, 3H-1,2,3-triazolo[4,5-b]pyridin-3-ol, 1H- 1,2,3-triazolo[4,5-b]pyridine, 1-ethenyl-1H-1,2,3-triazolo[4,5-b]pyridine, 3-hydroxypyridine, 1 , 2,4-triazolo[1,5-a]pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 2-methyl- 5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7-diphenyl-[1,2,4]tri Azolo[1, 5-a]pyrimidine and 2-methylthio-5,7- A group consisting of diphenyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine. The abrasive according to claim 1, wherein the content of the metal corrosion inhibitor is from 0.001% by mass to 10% by mass based on the total mass of the abrasive. The abrasive according to claim 1, wherein a ratio of the carboxylic acid derivative to the metal corrosion inhibitor (carboxylic acid derivative/metal corrosion inhibitor) is in a range of from 10/1 to 1/5 by mass ratio. . The abrasive according to claim 1, wherein a ratio of the carboxylic acid derivative to the metal corrosion inhibitor (carboxylic acid derivative/metal corrosion inhibitor) is in a range of 5/1 to 1/5 by mass ratio. . The abrasive according to claim 1, which further comprises an oxidizing agent. The abrasive according to claim 15, wherein the oxidizing agent is at least selected from the group consisting of hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, and ozone water. One. The abrasive according to claim 15, wherein the content of the oxidizing agent is 0.01% by mass to 50% by mass based on the total mass of the abrasive. The abrasive according to claim 1, which further comprises an organic solvent. The abrasive according to claim 18, wherein the organic solvent is water-soluble. The abrasive according to claim 18, wherein the organic solvent is selected from the group consisting of a carbonate solvent, a lactone solvent, a glycol solvent, and an ether. At least one of a group consisting of a solvent, an alcohol solvent, a ketone solvent, and a derivative of a diol solvent. The abrasive according to claim 18, wherein the content of the organic solvent is from 0.1% by mass to 95% by mass based on the total mass of the abrasive. The abrasive according to claim 1, which further comprises a water-soluble polymer. The abrasive according to claim 22, wherein the water-soluble polymer has a carboxylic acid group or a carboxylate group. The abrasive according to claim 22, wherein the water-soluble polymer has a weight average molecular weight of 500 to 1,000,000. The abrasive according to claim 22, wherein the content of the water-soluble polymer is from 0.001% by mass to 10% by mass based on the total mass of the abrasive. The abrasive according to claim 1, which further comprises abrasive particles. The abrasive according to claim 26, wherein the abrasive particles are selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, cerium oxide, titanium oxide, cerium oxide, cerium carbide, polystyrene, polyacrylic acid, and polychlorinated chlorine. At least one of the groups consisting of ethylene. The abrasive according to claim 26, wherein the abrasive grains have an average particle diameter of 10 nm to 100 nm. The abrasive according to claim 26, wherein the content of the abrasive grains is 1.0% by mass or more based on the total mass of the abrasive. A method of polishing a substrate, wherein the abrasive film containing a cobalt element formed on at least one surface of the substrate is ground using an abrasive according to any one of claims 1 to 29, The excess containing cobalt is removed. A use of an abrasive according to any one of claims 1 to 29 for grinding a layer containing a cobalt element.