JP2020047832A - Aqueous dispersion for chemical mechanical polishing and method of producing the same, and chemical mechanical polishing method - Google Patents

Abstract

To provide an aqueous dispersion for chemical mechanical polishing allowing for high-speed polishing of a substrate including a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material while suppressing corrosion of the wiring material and the like, and a method of producing the aqueous dispersion for chemical mechanical polishing.SOLUTION: The method of producing the aqueous dispersion for chemical mechanical polishing according to the present invention includes a step (I) of hydrolyzing and condensing silicon alkoxide in an aqueous medium including a tertiary amine compound, a step (IV) of further dropping silicon alkoxide into the aqueous medium, and growing colloidal silica abrasive grains having a zeta potential of +1 mV or more and +5 mV or less, and a step (V) of, after the step (IV), adding to the aqueous medium, an amine compound, and at least one selected from the group consisting of metal nitrates and metal sulfates.SELECTED DRAWING: None

Description

  The present invention relates to a chemical mechanical polishing aqueous dispersion, a method for producing the same, and a chemical mechanical polishing method.

  2. Description of the Related Art CMP (Chemical Mechanical Polishing) has been rapidly spread by flattening technology and the like in the manufacture of semiconductor devices. In this CMP, the object to be polished is pressed against a polishing pad, and the object to be polished and the polishing pad are slid relative to each other while supplying an aqueous dispersion for chemical mechanical polishing onto the polishing pad. And it is a technique of mechanically polishing.

  2. Description of the Related Art In recent years, as semiconductor devices have become finer, wiring layers formed in the semiconductor device, such as wiring and plugs, have been miniaturized. Accordingly, a technique of flattening the wiring layer by CMP has been used. The substrate in the semiconductor device includes an insulating film material, a wiring material, a barrier metal material for preventing the wiring material from diffusing into the inorganic material film, and the like. Here, for example, silicon dioxide is mainly used as an insulating film material, copper or tungsten is used as a wiring material, and tantalum nitride or titanium nitride is mainly used as a barrier metal material.

  In order to polish such an insulating film material, a wiring material, a barrier metal material, and the like at high speed, for example, in Patent Document 1, a chemical containing silica abrasive grains having a permanent positive charge of 6 mV or more, an amine compound, iron nitrate, and the like are used. Mechanical polishing compositions are disclosed.

JP-T-2017-514295

  The chemical mechanical polishing composition described in Patent Document 1 improves the dispersion stability of the abrasive grains and improves the polishing characteristics of the tungsten substrate by making the surface of the abrasive grains a stable positive charge. This is presumed to be because the use of abrasive grains having a high zeta potential value suppressed aggregation by electrostatic repulsion and significantly exhibited the effect of adhesion to the tungsten substrate. However, a wiring board used in a semiconductor device contains an insulating film material such as silicon dioxide and a barrier metal material such as titanium nitride in addition to a wiring material such as tungsten. When polishing such an insulating film material or the like, there is a problem that it is difficult to perform high-speed polishing with the chemical mechanical polishing composition described in Patent Document 1.

  Therefore, some aspects of the present invention provide a chemical compound capable of polishing a substrate including a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material at high speed while suppressing corrosion of a wiring material and the like. An aqueous dispersion for mechanical polishing and a method for producing the same are provided. Further, some aspects according to the present invention provide an aqueous dispersion for chemical mechanical polishing in which the dispersion stability of abrasive grains is improved, and a method for producing the same.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as any of the following aspects.

One embodiment of the method for producing an aqueous dispersion for chemical mechanical polishing according to the present invention,
A method for producing an aqueous dispersion for chemical mechanical polishing, comprising colloidal silica abrasive grains, an amine compound, and at least one selected from the group consisting of metal nitrates and metal sulfates,
A step (I) of hydrolyzing and condensing a silicon alkoxide in an aqueous medium in which a tertiary amine compound is present;
After the step (I), a step (IV) of dropping silicon alkoxide into the aqueous medium to grow colloidal silica abrasive grains having a zeta potential of +1 mV or more and +5 mV or less;
A step (V) of adding an amine compound and at least one selected from the group consisting of metal nitrates and metal sulfates to the aqueous medium after the step (IV);
including.

In one embodiment of the method for producing the chemical mechanical polishing aqueous dispersion,
Further, after the step (I) and before the step (IV), a step (II) of concentrating the aqueous medium to remove an alcohol component can be included.

In any aspect of the method for producing the chemical mechanical polishing aqueous dispersion,
Further, after the step (I) and before the step (IV), a step (III) of adding a tertiary amine to the aqueous medium may be included.

In any aspect of the method for producing the chemical mechanical polishing aqueous dispersion,
Further, after the step (V), a step (VI) of adding hydrogen peroxide can be included.

In any aspect of the method for producing the chemical mechanical polishing aqueous dispersion,
The chemical mechanical polishing aqueous dispersion may be for polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride.

One embodiment of the chemical mechanical polishing aqueous dispersion according to the present invention,
(A) colloidal silica abrasive grains having a permanent positive charge of +1 mV or more and +5 mV or less,
(B) at least one selected from the group consisting of metal nitrates and metal sulfates;
(C) at least one selected from the group consisting of amine compounds and salts thereof,
(D) a chelating agent other than the component (C),
And the pH is 1 or more and 3 or less.

In one embodiment of the chemical mechanical polishing aqueous dispersion,
A tertiary amine compound may be included in the colloidal silica abrasive.

In any aspect of the chemical mechanical polishing aqueous dispersion,
The tertiary amine compound may be included in the colloidal silica abrasive.

In any aspect of the chemical mechanical polishing aqueous dispersion,
It can be for polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride.

One embodiment of the chemical mechanical polishing method according to the present invention,
The method includes a step of polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride using the chemical mechanical polishing aqueous dispersion according to any of the above aspects.

  According to the chemical mechanical polishing aqueous dispersion according to the present invention, a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material can be polished at a high speed while suppressing corrosion of a wiring material and the like. Can be. Further, according to the chemical mechanical polishing aqueous dispersion according to the present invention, the dispersion stability of the abrasive grains is improved.

It is the perspective view which showed the chemical mechanical polishing apparatus typically.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below, but also includes various modified examples implemented without departing from the gist of the present invention.

  In this specification, the numerical range described using “to” means that the numerical values described before and after “to” are included as the lower limit and the upper limit.

  “Wiring material” refers to a conductive metal material such as aluminum, copper, cobalt, titanium, ruthenium, and tungsten. “Insulating film material” refers to a material such as silicon dioxide, silicon nitride, amorphous silicon, and the like. The term “barrier metal material” refers to a material such as tantalum nitride or titanium nitride which is used by being laminated with a wiring material for the purpose of improving the reliability of the wiring.

1. A method for producing an aqueous dispersion for chemical mechanical polishing The method for producing an aqueous dispersion for chemical mechanical polishing according to this embodiment is selected from the group consisting of colloidal silica abrasives, amine compounds, metal nitrates and metal sulfates. This is a method for producing an aqueous dispersion for chemical mechanical polishing containing at least one kind. The method for producing an aqueous dispersion for chemical mechanical polishing according to the present embodiment comprises a step (I) of hydrolyzing and condensing a silicon alkoxide in an aqueous medium in which a tertiary amine compound is present, and after the step (I). A step (IV) of dropping silicon alkoxide into the aqueous medium to grow colloidal silica abrasive particles having a zeta potential of +1 mV or more and +5 mV or less; and after the step (IV), an amine compound is added to the aqueous medium. (V) adding at least one selected from the group consisting of metal nitrates and metal sulfates. Hereinafter, each step included in the method for producing the chemical mechanical polishing aqueous dispersion according to the present embodiment will be described in detail.

1.1. Step (I)
In the step (I), the silicon alkoxide is hydrolyzed and condensed in an aqueous medium containing a tertiary amine compound. Specifically, when the aqueous medium is 100 parts by mass, a tertiary amine compound is added in an amount of 0.03 parts by mass or more and 2 parts by mass or less, and after sufficient stirring, 1.4 parts by mass of silicon alkoxide is obtained. To 50 parts by mass and hydrolyzed and condensed under a temperature condition of 25 ° C to 100 ° C. Thus, an aqueous dispersion containing colloidal silica abrasive grains can be obtained.

  Examples of the tertiary amine compound include triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, trimethylamine, triethylamine, tripropylamine and tributylamine. , Dimethylglycine and tetramethylethylenediamine. Among these, triethanolamine and N, N-dimethylethanolamine are preferred, and triethanolamine is more preferred.

The lower limit of the amount of the tertiary amine compound to be added is 10% in the aqueous medium before the addition of the tertiary amine compound.
When the amount is 0 parts by mass, the amount is preferably 0.03 parts by mass, more preferably 0.1 part by mass, and particularly preferably 0.3 parts by mass. On the other hand, the upper limit of the addition amount of the tertiary amine compound is preferably 2 parts by mass, more preferably 1 part by mass, and particularly preferably 0.6 part by mass. When the amount of the tertiary amine compound is within the above range, the zeta potential of the obtained silica abrasive grains can be easily adjusted to +1 mV or more and +5 mV or less.

  In the operation of adding the silicon alkoxide to the aqueous medium, it is preferable to prepare a mixed liquid of the silicon alkoxide and the alcohol and gradually drop the mixed liquid to the aqueous medium. By doing so, an aqueous dispersion containing colloidal silica abrasive grains having a uniform particle size in an aqueous medium can be obtained. After the addition of the silicon alkoxide, hydrolysis and condensation are preferably performed under a temperature condition of preferably 25 ° C to 100 ° C, more preferably 50 ° C to 95 ° C. By performing hydrolysis and condensation within the above-mentioned temperature range, colloidal silica abrasive grains having excellent dispersibility are easily generated.

  Examples of the silicon alkoxide include, for example, tetramethoxysilane, tetraethoxysilane, allyltriethoxysilane, benzyltriethoxysilane, 1,2-bis (trimethoxysilyl) ethane, cyclopentyltrimethoxysilane, decyltrimethoxysilane, decyltriethoxysilane Examples include silane and cyclohexyl (dimethoxy) methylsilane. Among these, tetramethoxysilane and tetraethoxysilane are preferable, and tetramethoxysilane is particularly preferable. With such a silicon alkoxide, the obtained colloidal silica abrasive grains have an appropriate hardness and are excellent in polishing characteristics of a wiring material such as tungsten.

  The lower limit of the addition amount of the silicon alkoxide is preferably 1.4 parts by mass, more preferably 5 parts by mass, when the aqueous medium before the addition of the tertiary amine compound is 100 parts by mass. Particularly preferred is 10 parts by mass. On the other hand, the upper limit of the addition amount of the silicon alkoxide is preferably 50 parts by mass, more preferably 40 parts by mass, and particularly preferably 20 parts by mass. When the addition amount of the silicon alkoxide is within the above range, the zeta potential of the obtained colloidal silica abrasive grains can be easily adjusted to +1 mV or more and +5 mV or less due to the interaction with the tertiary amine compound.

1.2. Step (II)
Next, after the step (I) and before the step (IV) described below, a step (II) of concentrating the aqueous dispersion containing the colloidal silica abrasive obtained in the step (I) to remove an alcohol component is performed. It is preferred to do so. The step (II) is more preferably performed after the step (I) and before the step (III) described later.

  In the step (II), an operation of removing an alcohol component while adding water is performed using, for example, an evaporator. Thereby, an aqueous dispersion containing colloidal silica abrasive grains from which the alcohol component has been removed is obtained. Through the step (II), it becomes easy to adjust the zeta potential of the obtained colloidal silica abrasive grains to +1 mV or more and +5 mV or less.

1.3. Step (III)
Next, it is preferable to include a step (III) of further adding a tertiary amine compound to the aqueous dispersion after the step (I) and before the step (IV) described later. The step (III) is more preferably performed after the step (II) and before the step (IV) described later.

By further adding a tertiary amine compound to the aqueous dispersion, the tertiary amine compound and the silicon alkoxide are likely to interact with each other. Therefore, the zeta potential of the obtained colloidal silica abrasive particles is set to +1 mV or more and +5 mV or less. As well as being easy to adjust, colloidal silica abrasive grains having excellent polishing characteristics are easily produced.

  The tertiary amine compound added in the step (III) is preferably the same as the tertiary amine compound added in the step (I), but may be a different kind. The lower limit of the amount of the tertiary amine compound to be added in the step (III) is preferably 0.03 parts by mass, when the aqueous dispersion obtained in the step (I) is 100 parts by mass. , 0.3 parts by mass. On the other hand, the upper limit of the amount of the tertiary amine compound added in step (III) is preferably 1 part by mass, more preferably 0.8 part by mass.

1.4. Step (IV)
Next, in the step (IV), after the step (I), silicon alkoxide is further dropped into the aqueous dispersion to grow colloidal silica abrasive grains having a zeta potential of +1 mV or more and +5 mV or less. Through the step (IV), the colloidal silica abrasive obtained in the step (I) can be grown, and an aqueous dispersion containing the colloidal silica abrasive having excellent polishing characteristics can be produced.

  As the silicon alkoxide to be added in step (IV), it is preferable to add the same type of silicon alkoxide as in step (I), but it may be of a different type. The lower limit of the addition amount of the silicon alkoxide added in the step (IV) is preferably 5 parts by weight, and more preferably 10 parts by weight, when the aqueous dispersion obtained in the step (I) is 100 parts by weight. More preferably, there is. On the other hand, the upper limit of the amount of silicon alkoxide added in step (IV) is preferably 40 parts by mass, and more preferably 25 parts by mass.

  In the method for producing an aqueous dispersion for chemical mechanical polishing according to the present embodiment, it is preferable that step (I), step (II), step (III), and step (IV) are performed in this order. Further, when the step (II) to the step (IV) are performed a plurality of times, the tertiary amine compound and the silicon alkoxide are likely to interact with each other, so that the zeta potential of the obtained colloidal silica abrasive particles is set to +1 mV or more and +5 mV or less. In addition to being easily adjusted, colloidal silica abrasive grains having excellent polishing characteristics may be easily produced.

1.5. Step (V)
Next, in step (V), after step (IV), an amine compound and at least one selected from the group consisting of metal nitrates and metal sulfates are added to the aqueous dispersion containing the colloidal silica abrasive grains. . Through the step (V), the chemical mechanical polishing aqueous dispersion of the present invention is obtained. The chemical mechanical polishing aqueous dispersion of the present invention can polish a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material at a high speed while suppressing corrosion of the wiring material. Further, the chemical mechanical polishing aqueous dispersion of the present invention can improve the dispersion stability of colloidal silica abrasive grains.

  Examples of the amine compound added in the step (V) include polynitrogen-containing compounds such as 2-aminoethylpiperazine, 1,4-bis (3-aminopropyl) piperazine, and triethylenetetramine; sodium laurylaminodipropionate; Amphoteric surfactants such as sodium N-lauroyl-N'-carboxymethyl-N'-hydroxyethylethylenediamine; and cationic polymers such as polyethyleneimine. Among these, an amphoteric surfactant and a cationic polymer are preferred, and a betaine-type amphoteric surfactant containing a carboxyl group having 12 or more carbon chains (excluding aminocarboxylic acid) is particularly preferred. The aqueous dispersion for chemical mechanical polishing containing such an amine compound can improve the dispersion stability of colloidal silica abrasive grains in the aqueous dispersion while suppressing corrosion of the wiring material.

The lower limit of the amount of the amine compound to be added is preferably 0.001 part by mass, more preferably 0.01 part by mass, when the aqueous medium after the step (IV) is 100 parts by mass. On the other hand, the upper limit of the amount of the amine compound added is preferably 1 part by mass, more preferably 0.5 part by mass.

  Examples of the metal nitrate added in the step (V) include copper nitrate, cobalt nitrate, zinc nitrate, manganese nitrate, iron nitrate, molybdenum nitrate, bismuth nitrate, and cerium nitrate. Examples of the metal sulfate added in the step (V) include copper sulfate, cobalt sulfate, zinc sulfate, manganese sulfate, iron sulfate, and silver sulfate. Among these, at least one selected from the group consisting of copper nitrate, iron nitrate, copper sulfate and iron sulfate is preferable, and at least one selected from the group consisting of iron nitrate and iron sulfate is preferable. More preferred. Since these compounds have particularly high oxidizing power among metal nitrates and metal sulfates, they can passivate the surface of a wiring material or a barrier metal material to form an oxide layer. Then, by utilizing the mechanical polishing action of the colloidal silica abrasive, the oxide layer can be removed at a high speed.

  The lower limit of the addition amount of at least one selected from the group consisting of metal nitrates and metal sulfates is 0.001 part by mass when the aqueous medium after the step (IV) is 100 parts by mass. More preferably, it is 0.01 part by mass. On the other hand, the upper limit of the addition amount of at least one selected from the group consisting of metal nitrates and metal sulfates is preferably 1 part by mass, more preferably 0.5 part by mass.

1.6. Step (VI)
Next, after the step (V), a step (VI) of adding hydrogen peroxide to the chemical mechanical polishing aqueous dispersion obtained in the step (V) may be included. When the metal sulfate and / or metal nitrate added in the step (V) is used in combination with hydrogen peroxide, a strong oxidation reaction (Fenton reaction) may occur, and the wiring material or the barrier metal material may be polished at high speed. Since hydrogen peroxide is unstable and easily releases oxygen, and easily generates a hydroxyl radical having a very strong oxidizing power, the step (VI) is preferably performed immediately before performing the CMP.

  The lower limit of the added amount of hydrogen peroxide is preferably 0.001 part by mass, more preferably 0.005 part by mass, when the chemical mechanical polishing aqueous dispersion obtained in the step (V) is 100 parts by mass. Preferably, 0.01 parts by mass is particularly preferred. On the other hand, the upper limit of the added amount of hydrogen peroxide is preferably 5 parts by mass, more preferably 3 parts by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion obtained in step (V). 5 parts by weight are particularly preferred.

2. Aqueous dispersion for chemical mechanical polishing The aqueous dispersion for chemical mechanical polishing according to this embodiment can be manufactured by the above-described manufacturing method, but is not limited to the one manufactured by the above-described manufacturing method. The chemical mechanical polishing aqueous dispersion according to this embodiment includes (A) colloidal silica abrasive grains having a permanent positive charge of +1 mV or more and +5 mV or less (also referred to as “(A) component”), (B) metal nitrate and At least one selected from the group consisting of metal sulfates (also referred to as “component (B)”) and at least one selected from the group consisting of (C) amine compounds and salts thereof (“component (C)” ) And (D) a chelating agent other than the component (C) (also referred to as the “component (D)”), and the pH is 1 or more and 3 or less. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion according to the present embodiment will be described in detail.

2.1. (A) Colloidal silica abrasive particles The chemical mechanical polishing aqueous dispersion according to the present embodiment contains (A) colloidal silica abrasive particles having a permanent positive charge of +1 mV or more and +5 mV or less. One of the functions of the component (A) is to mechanically polish a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material to improve a polishing rate. In particular, the polishing rate of a substrate containing tungsten as a wiring material, silicon dioxide as an insulating film material, and titanium nitride as a barrier metal material can be improved.

  Here, "colloidal silica abrasive grains having a permanent positive charge" refers to ion-exchanged water (water is Kurita Kogyo Co., Ltd., model "Demiace DZ-50C") in which the amount of colloidal silica abrasive grains is 1% by mass. Exchanged) and passed through a colloidal silica abrasive aqueous dispersion having a pH adjusted to 2.4 three times through a 0.3 μm pore size polypropylene filtration filter (Model Planagard PCL0301E6) manufactured by Entegris. This means that the change in the absolute value of the zeta potential before and after filtration is 4 mV or less. Further, the absolute value of the zeta potential of the colloidal silica abrasive grains after passing through such three times is preferably 3 mV or less, more preferably 1 mV or less. That is, “(A) colloidal silica abrasive grains having a permanent positive charge of +1 mV or more and +5 mV or less” means that the zeta potential is +1 mV or more and +5 mV or less before and after the three times of filtration, and the zeta potential before and after the filtration is respectively. A change in absolute value of 4 mV or less.

  If the colloidal silica abrasive particles having a permanent positive charge in the above range, it is possible to improve the polishing rate of the substrate containing a plurality of materials such as wiring material, insulating film material, and barrier metal material, particularly as a wiring material The polishing rate of a material containing tungsten, silicon dioxide as an insulating film material, and titanium nitride as a barrier metal material can be improved. In addition, if colloidal silica abrasive grains having a permanent positive charge within the above range, dispersion stability is likely to be good.

  In addition, the component (A) is preferably a colloidal silica abrasive containing a tertiary amine compound, and more preferably a colloidal silica abrasive containing a tertiary amine compound. Since the tertiary amine compound is contained in the colloidal silica abrasive grains, the component (A) tends to have a permanent positive charge of +1 mV or more and +5 mV or less, so that a wiring material, an insulating film material, a barrier metal material, etc. It is easy to improve the polishing rate of a substrate containing a plurality of materials.

  Examples of the tertiary amine compound include triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, trimethylamine, triethylamine, tripropylamine and tributylamine. , Dimethylglycine and tetramethylethylenediamine. Among these, triethanolamine and N, N-dimethylethanolamine are preferred, and triethanolamine is more preferred.

  The method for producing the component (A) is not particularly limited, but the component (A) can be suitably produced by a method for producing colloidal silica abrasive grains including the steps (I) to (IV).

The average particle diameter of the component (A) is preferably 5 nm or more and 300 nm or less. When the average particle diameter of the component (A) is within the above range, the polishing rate of a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material is improved while suppressing the occurrence of polishing scratches on the surface to be polished. May be possible. Here, among the above ranges, the component (A) having an average particle diameter in the range of 10 nm or more and 150 nm or less can particularly improve the polishing rate in some cases. In addition, among the above ranges, the component (A) having an average particle diameter in a range of 10 nm or more and 100 nm or less may be able to particularly suppress generation of polishing scratches generated on a surface to be polished. Here, the average particle diameter of the component (A) can be determined by measuring with a particle size distribution measuring apparatus using a dynamic light scattering method as a measurement principle. Examples of the particle size measuring device by the dynamic light scattering method include a dynamic light scattering type particle size distribution measuring device “LB-550” manufactured by Horiba, a nano-abrasive analyzer “DelsaNanoS” manufactured by Beckman Coulter, and a Malvern company. "Zetasizernanozs" manufactured by the company. The average particle diameter measured using the dynamic light scattering method represents the average particle diameter of secondary particles formed by aggregating a plurality of primary particles.

  The lower limit of the content of the component (A) is preferably 0.05% by mass, more preferably 0.1% by mass, and particularly preferably 0.3% by mass, based on the total mass of the aqueous dispersion for chemical mechanical polishing. preferable. When the content of the component (A) is at least the lower limit, the polishing rate of a substrate containing a plurality of materials may be able to be improved. On the other hand, the upper limit of the content of the component (A) is preferably 10% by mass, more preferably 5% by mass, and particularly preferably 3% by mass, based on the total mass of the aqueous dispersion for chemical mechanical polishing. When the content of the component (A) is equal to or less than the upper limit, the dispersion stability is likely to be good, and the flatness of the surface to be polished and the reduction of polishing scratches in the chemical mechanical polishing step may be realized.

2.2. Metal nitrate, metal sulfate The chemical mechanical polishing aqueous dispersion according to the present embodiment contains at least one selected from the group consisting of (B) a metal nitrate and a metal sulfate. One of the functions of the component (B) is to form an oxide layer on the surface of a substrate including a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material to improve a polishing rate. Among these materials, the polishing rate can be improved particularly for a substrate containing tungsten as a wiring material.

  Examples of the metal nitrate include copper nitrate, cobalt nitrate, zinc nitrate, manganese nitrate, iron nitrate, molybdenum nitrate, bismuth nitrate, and cerium nitrate. Examples of the metal sulfate include copper sulfate, cobalt sulfate, zinc sulfate, manganese sulfate, iron sulfate, and silver sulfate. Among these, at least one selected from the group consisting of copper nitrate, iron nitrate, copper sulfate and iron sulfate is preferable, and at least one selected from the group consisting of iron nitrate and iron sulfate is preferable. More preferred. Since these compounds have particularly high oxidizing power among metal nitrates and metal sulfates, they can passivate the surface of a wiring material or a barrier metal material to form an oxide layer. Then, by utilizing the mechanical polishing action of the colloidal silica abrasive, the oxide layer can be removed at a high speed.

  The lower limit of the content of the component (B) is preferably 0.001% by mass, more preferably 0.01% by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion. On the other hand, the upper limit of the content of the component (B) is preferably 1% by mass, and more preferably 0.5% by mass. When the content of the component (B) is within the above range, the polishing rate for a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material is improved. In particular, the polishing rate for a substrate containing tungsten as a wiring material is improved.

2.3. (C) Amine compound and salt thereof The aqueous dispersion for chemical mechanical polishing according to the present embodiment contains at least one selected from the group consisting of (C) an amine compound and a salt thereof. One of the functions of the component (C) is to suppress corrosion of wiring materials and the like. In particular, corrosion of a substrate containing tungsten as a wiring material can be suppressed. Another function of the component (C) is to improve the dispersion stability of the component (A) in the aqueous dispersion for chemical mechanical polishing.

The component (C) is not particularly limited as long as it is a compound containing an amine. For example, polynitrogen-containing compounds such as 2-aminoethylpiperazine, 1,4-bis (3-aminopropyl) piperazine, and triethylenetetramine; Amphoteric surfactants such as sodium laurylaminodipropionate and sodium N-lauroyl-N'-carboxymethyl-N'-hydroxyethylethylenediamine (excluding aminocarboxylic acid); and cationic polymers such as polyethyleneimine. . Among these, an amphoteric surfactant and a cationic polymer are preferred, and a betaine-type amphoteric surfactant containing a carboxyl group having 12 or more carbon chains is particularly preferred. The aqueous dispersion for chemical mechanical polishing containing such an amine compound can improve the dispersion stability of colloidal silica abrasive grains in the aqueous dispersion while suppressing corrosion of the wiring material. As the component (C), one type may be used alone, or two or more types may be used in combination at any ratio.

  As a specific example of the salt of the amine compound, the salt of the amine compound exemplified above may be used, and the salt of the amine compound is formed by reacting with the additive separately added in the aqueous dispersion for chemical mechanical polishing. There may be.

  The lower limit of the content of the component (C) is preferably 0.001% by mass, more preferably 0.01% by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion. On the other hand, the upper limit of the content of the component (C) is preferably 1% by mass, and more preferably 0.5% by mass. When the content of the component (C) is within the above range, corrosion of the wiring material and the like can be more effectively suppressed.

2.4. (D) Chelating Agent The aqueous dispersion for chemical mechanical polishing according to this embodiment contains (D) a chelating agent other than the component (C). One of the functions of the component (D) is to improve the polishing rate for a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material. In particular, the polishing rate for a substrate containing tungsten as a wiring material can be improved.

  The component (D) is not particularly limited as long as it is a compound having a chelating action, but is preferably at least one selected from the group consisting of organic acids and salts thereof.

  Such organic acids include, for example, phosphonic acids, lactic acid, tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, malic acid, malonic acid, glutaric acid, succinic acid Benzoic acid, p-hydroxybenzoic acid, quinolinic acid, quinaldic acid, amidosulfuric acid; glycine, alanine, aspartic acid, glutamic acid, lysine, arginine, tryptophan, arginine, histidine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and other aminocarboxylic acids Is mentioned. Among these, at least one selected from the group consisting of phosphonic acids, maleic acid, succinic acid, lactic acid, malonic acid, and aminocarboxylic acid is preferable, and malonic acid, 1-hydroxyethylidene-1,1-diphosphone is preferred. More preferably, it is at least one selected from the group consisting of an acid and diethylenetriaminepentaacetic acid, and malonic acid is particularly preferred. Such organic acids may be used alone or in combination of two or more at any ratio.

  As a specific example of the salt of an organic acid, the salt of the organic acid may be used, and the salt of the organic acid is formed by reacting with a base added separately in the chemical mechanical polishing aqueous dispersion. Is also good. Examples of such a base include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide, organic alkali compounds such as tetramethylammonium hydroxide (TMAH) and choline, and ammonia and the like. Is mentioned.

  The lower limit of the content of the component (D) is preferably 0.001 part by mass, more preferably 0.01 part by mass, based on the total mass of the chemical mechanical polishing aqueous dispersion. On the other hand, the upper limit of the content of the component (D) is preferably 1 part by mass, and more preferably 0.5 part by mass. When the content of the component (D) is within the above range, the polishing rate for a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material is improved.

2.5. Other components The chemical mechanical polishing aqueous dispersion according to this embodiment is, in addition to water as a main liquid medium, if necessary, a water-soluble polymer, an oxidizing agent, a surfactant, and a nitrogen-containing heterocyclic compound. , A pH adjuster and the like.

<Water>
The chemical mechanical polishing aqueous dispersion according to this embodiment contains water as a main liquid medium. The water is not particularly limited, but pure water is preferred. Water only needs to be blended as the balance of the constituent material of the aqueous dispersion for chemical mechanical polishing described above, and the content of water is not particularly limited.

<Water-soluble polymer>
The chemical mechanical polishing aqueous dispersion according to the present embodiment may contain a water-soluble polymer. By containing a water-soluble polymer, it may be possible to reduce polishing friction by adsorbing to a surface to be polished such as a wiring material. The water-soluble polymer is preferably a polycarboxylic acid, and more preferably at least one selected from the group consisting of polyacrylic acid, polymaleic acid, and a copolymer thereof.

  The weight average molecular weight (Mw) of the water-soluble polymer is preferably from 1,000 to 1,000,000, more preferably from 3,000 to 800,000. When the weight average molecular weight of the water-soluble polymer is in the above range, the water-soluble polymer tends to be adsorbed on the surface to be polished such as a wiring material, and the polishing friction may be further reduced. As a result, the occurrence of polishing scratches on the surface to be polished may be more effectively reduced. In addition, the “weight average molecular weight (Mw)” in this specification refers to a weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

  When the chemical mechanical polishing aqueous dispersion according to the present embodiment contains a water-soluble polymer, the content of the water-soluble polymer is 0.01 to 1 with respect to the total mass of the chemical mechanical polishing aqueous dispersion. % By mass is preferable, and 0.03 to 0.5% by mass is more preferable.

  The content of the water-soluble polymer also depends on the weight-average molecular weight (Mw) of the water-soluble polymer, but may be adjusted so that the viscosity of the chemical mechanical polishing aqueous dispersion is less than 10 mPa · s. preferable. When the viscosity of the chemical mechanical polishing aqueous dispersion is less than 10 mPa · s, it is easy to polish a wiring material at a high speed, and since the viscosity is appropriate, the chemical mechanical polishing aqueous dispersion is stably supplied on the polishing cloth. can do.

<Oxidizing agent>
The chemical mechanical polishing aqueous dispersion according to the present embodiment may contain an oxidizing agent different from the component (B). By containing an oxidizing agent different from the component (B), it is possible to create a fragile modified layer on the surface to be polished by oxidizing the wiring material and the like to promote a complexing reaction with the polishing liquid component. , It may be easier to polish.

  Examples of the oxidizing agent include ammonium persulfate, hydrogen peroxide, potassium hypochlorite, ozone, potassium periodate, and peracetic acid. Among these oxidizing agents, at least one selected from potassium periodate, potassium hypochlorite and hydrogen peroxide is preferable, and hydrogen peroxide is more preferable. These oxidizing agents may be used alone or in a combination of two or more.

When the chemical mechanical polishing aqueous dispersion according to the present embodiment contains an oxidizing agent, the content of the oxidizing agent is preferably 0.001 to 5% by mass based on the total mass of the chemical mechanical polishing aqueous dispersion. , More preferably 0.005 to 3% by mass, and particularly preferably 0.01 to 1.5% by mass. In addition, when hydrogen peroxide is added as an oxidizing agent, hydrogen peroxide is unstable and easily releases oxygen, and easily generates a hydroxyl radical having a very strong oxidizing power. Therefore, hydrogen peroxide is added immediately before performing CMP. Is preferred.

<Surfactant>
The chemical mechanical polishing aqueous dispersion according to this embodiment may contain a surfactant other than the surfactants exemplified above. By containing a surfactant, an appropriate viscosity may be imparted to the chemical mechanical polishing aqueous dispersion in some cases.

  The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Examples of the anionic surfactant include carboxylate such as fatty acid soap and alkyl ether carboxylate; sulfonate such as alkyl benzene sulfonate, alkyl naphthalene sulfonate and α-olefin sulfonate; higher alcohol sulfate Sulfates such as ester salts, alkyl ether sulfates and polyoxyethylene alkyl phenyl ether sulfates; and fluorinated surfactants such as perfluoroalkyl compounds. Examples of the cationic surfactant include an aliphatic amine salt and an aliphatic ammonium salt. Examples of the nonionic surfactant include nonionic surfactants having a triple bond, such as acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol; and polyethylene glycol type surfactants. These surfactants may be used alone or in combination of two or more.

  When the chemical mechanical polishing aqueous dispersion according to the present embodiment contains a surfactant, the content of the surfactant is preferably 0.001 to 5 with respect to the total mass of the chemical mechanical polishing aqueous dispersion. %, More preferably 0.001 to 3% by mass, and particularly preferably 0.01 to 1% by mass.

<Nitrogen-containing heterocyclic compound>
The chemical mechanical polishing aqueous dispersion according to the present embodiment may contain a nitrogen-containing heterocyclic compound. By containing the nitrogen-containing heterocyclic compound, excessive etching of the wiring material may be suppressed, and surface roughness after polishing may be prevented.

  As used herein, the term "nitrogen-containing heterocyclic compound" refers to an organic compound containing at least one heterocyclic ring selected from a five-membered heterocyclic ring and a six-membered heterocyclic ring having at least one nitrogen atom. Examples of the heterocycle include a five-membered heterocyclic ring such as a pyrrole structure, an imidazole structure, and a triazole structure; and a six-membered heterocyclic ring such as a pyridine structure, a pyrimidine structure, a pyridazine structure, and a pyrazine structure. These heterocycles may form a condensed ring. Specific examples include an indole structure, an isoindole structure, a benzimidazole structure, a benzotriazole structure, a quinoline structure, an isoquinoline structure, a quinazoline structure, a cinnoline structure, a phthalazine structure, a quinoxaline structure, and an acridine structure. Among the heterocyclic compounds having such a structure, a heterocyclic compound having a pyridine structure, a quinoline structure, a benzimidazole structure or a benzotriazole structure is preferable.

  Specific examples of the nitrogen-containing heterocyclic compound include aziridine, pyridine, pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzoisoquinoline, purine, pteridine, triazole, triazolidine, benzotriazole, carboxy Examples include benzotriazole and the like, and further, derivatives having these skeletons. Among these, benzotriazole, triazole, imidazole and carboxybenzotriazole are preferred. These nitrogen-containing heterocyclic compounds may be used alone or in a combination of two or more.

  When the chemical mechanical polishing aqueous dispersion according to the present embodiment contains a nitrogen-containing heterocyclic compound, the content of the nitrogen-containing heterocyclic compound is preferably 0 based on the total mass of the chemical mechanical polishing aqueous dispersion. 0.05 to 2% by mass, more preferably 0.1 to 1% by mass, and particularly preferably 0.2 to 0.6% by mass.

<PH adjuster>
The chemical mechanical polishing aqueous dispersion according to this embodiment may contain a pH adjuster in order to adjust the pH to 1 or more and 3 or less. By containing a pH adjuster, the pH is adjusted to 1 or more and 3 or less while appropriately adjusting the amounts of the components (B), (C) and (D) so that the desired effects of the present invention can be obtained. In some cases. Examples of the pH adjuster include inorganic acids such as phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid, and salts thereof, and one or more of these can be used.

2.6. pH
The pH value of the chemical mechanical polishing aqueous dispersion according to this embodiment is 1 or more and 3 or less, and more preferably 1 or more and 2.5 or less. When the pH is within the above range, the zeta potential of the component (A) can be easily maintained at +1 mV or more and +5 mV or less. As a result, the dispersion stability of the component (A) in the chemical mechanical polishing aqueous dispersion is improved. When the pH is within the above range, the polishing rate for a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material is improved.

  The pH of the chemical mechanical polishing aqueous dispersion according to this embodiment is adjusted by, for example, appropriately increasing or decreasing the amounts of components (B), (C), (D), and a pH adjuster. can do.

  In the present invention, pH refers to a hydrogen ion index, and the value is measured using a commercially available pH meter (for example, a desktop pH meter manufactured by HORIBA, Ltd.) at 25 ° C. and 1 atm. can do.

2.7. The chemical mechanical polishing aqueous dispersion according to this embodiment has a composition suitable for polishing a substrate containing a plurality of materials such as a wiring material, an insulating film material, and a barrier metal material at a high speed. Corrosion of wiring materials and barrier metal materials can also be suppressed. Among these materials, the chemical mechanical polishing aqueous dispersion according to the present embodiment includes a substrate containing tungsten as a wiring material, a material containing silicon such as silicon dioxide as an insulating film material, and a substrate containing titanium nitride as a barrier metal material. Polishing can be performed at high speed, and corrosion of tungsten and titanium nitride can be particularly suppressed. Therefore, the chemical mechanical polishing aqueous dispersion according to the present embodiment is particularly suitable for polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride.

3. Chemical-mechanical polishing method The chemical-mechanical polishing method according to the present embodiment comprises, using the above-described chemical mechanical polishing aqueous dispersion, a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride. (Chemical machine) Includes a polishing step. According to the chemical mechanical polishing method according to the present embodiment, by using the chemical mechanical polishing aqueous dispersion, tungsten, silicon dioxide, and titanium nitride can be polished at high speed, and the corrosion of tungsten and titanium nitride Can also be suppressed.

For the chemical mechanical polishing described above, for example, a polishing apparatus 100 as shown in FIG. 1 can be used. FIG. 1 is a perspective view schematically showing the polishing apparatus 100. In the above-described chemical mechanical polishing, a carrier (aqueous dispersion for chemical mechanical polishing) 44 is supplied from a slurry supply nozzle 42 and a carrier head holding a substrate 50 while rotating a turntable 48 to which a polishing cloth 46 is attached. This is carried out by bringing 52 into contact. FIG. 1 also shows the water supply nozzle 54 and the dresser 56.

  The polishing load of the carrier head 52 can be selected within the range of 0.7 to 70 psi, and is preferably 1.5 to 35 psi. The number of rotations of the turntable 48 and the carrier head 52 can be appropriately selected within a range of 10 to 400 rpm, and is preferably 30 to 150 rpm. The flow rate of the slurry (aqueous dispersion for chemical mechanical polishing) 44 supplied from the slurry supply nozzle 42 can be selected within a range of 10 to 1,000 mL / min, and is preferably 50 to 400 mL / min.

Examples of commercially available polishing apparatuses include, for example, models “EPO-112” and “EPO-222” manufactured by Ebara Corporation; models manufactured by Lapmaster SFT, models “LGP-510” and “LGP-552”; manufactured by Applied Materials. , Model "Mirra", "Reflexion"; G & P
TECHNOLOGY, model "POLI-400L"; AMAT, model "Reflexion LK"; FILTEC, model "FLTec-15"; Tokyo Seimitsu, model "ChaMP".

4. Examples Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

4.1. Preparation of Aqueous Dispersion Containing Colloidal Silica Abrasives (1) Preparation of Aqueous Dispersion Containing Colloidal Silica A1 100 g of 28% ammonia water, 160 g of ion-exchanged water, and 1250 g of methanol are charged into a flask having a capacity of 2000 cm ³ and stirred at 180 rpm. While the temperature was raised to 35 ° C. To this solution, a mixed solution of 160 g of tetramethoxysilane and 40 g of methanol was gradually added dropwise to obtain a colloidal silica / alcohol dispersion. Next, the operation of removing the alcohol content by adding an ion-exchanged water to the dispersion at 80 ° C. with an evaporator several times is repeated to remove the alcohol in the dispersion, and the water containing colloidal silica A1 having a solid concentration of 15% is contained. A dispersion was prepared.

(2) Preparation of Aqueous Dispersion Containing Colloidal Silica A2 1000 g of the aqueous dispersion containing colloidal silica A1 prepared above was heated to 60 ° C. with stirring, and further a mercapto group-containing silane coupling agent (Shin-Etsu Chemical Co., Ltd.) 1 g of a product (trade name “KBE803” manufactured by Co., Ltd.) was added thereto, and stirring was further continued for 2 hours. Thereafter, 8 g of 35% hydrogen peroxide solution was added, and the mixture was maintained at 60 ° C. with stirring for 8 hours. Thereafter, the mixture was cooled to room temperature to obtain an aqueous dispersion of colloidal silica A2 modified with a sulfo group.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 68 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A2 became 1% by mass, and adjusted to pH 2.4. The zeta potential of the colloidal silica A2 at that time was -34 mV. The zeta potential of colloidal silica A2 after filtration through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Integris Corporation was −31 mV.

(3) Preparation of aqueous dispersion containing colloidal silica A3 To 1000 g of the aqueous dispersion containing colloidal silica A1 prepared above, 28% aqueous ammonia was added to adjust the pH to 10.2. A mixture of 19 g of methanol and 1 g of 3-aminopropyltrimethoxysilane was added dropwise to this solution over 10 minutes while maintaining the solution temperature at 30 ° C., and the mixture was refluxed at normal pressure for 2 hours, thereby modifying with an amino group. An aqueous dispersion containing the obtained colloidal silica A3 was obtained.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 68 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A3 became 1% by mass, and adjusted to pH 2.4. The zeta potential of colloidal silica A3 at that time was +29 mV. The zeta potential of the colloidal silica A3 after filtration through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was +25 mV.

(4) Preparation of Aqueous Dispersion Containing Colloidal Silica A4 A flask having a capacity of 2000 cm ³ was charged with 60 g of 28% ammonia water and 1500 g of ion-exchanged water, and heated to 80 ° C. while stirring at 180 rpm. To this solution, a mixed solution of 280 g of tetramethoxysilane and 75 g of methanol was gradually added dropwise to obtain a colloidal silica / alcohol dispersion. Next, the operation of removing the alcohol content by adding an ion-exchanged water to the dispersion at 60 ° C. with an evaporator several times is repeated to remove the alcohol in the dispersion, and water containing colloidal silica A4 having a solid concentration of 15% is contained. A dispersion was prepared.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 27 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A4 became 1% by mass, and adjusted to pH 2.4. The zeta potential of the colloidal silica A4 at that time was -0.3 mV. The zeta potential of colloidal silica A4 after passing through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was −1 mV.

(5) Preparation of Aqueous Dispersion Containing Colloidal Silica A5 A flask having a capacity of 2000 cm ³ was charged with 6 g of triethanolamine and 1500 g of ion-exchanged water, and heated to 70 ° C. while stirring at 180 rpm. 280 g of tetramethoxysilane was gradually dropped into this solution to obtain a colloidal silica / methanol dispersion. Next, an operation of removing methanol from the dispersion by adding ion-exchanged water to the dispersion at 60 ° C. using an evaporator is performed to remove methanol in the dispersion, and to obtain an aqueous dispersion containing colloidal silica A5 having a solid content concentration of 15%. Was prepared.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 15 nm when measured.
Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A5 became 1% by mass, and adjusted to pH 2.4. The zeta potential of colloidal silica A5 at that time was -0.3 mV. The zeta potential of the colloidal silica A5 after passing through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was −1 mV.

(6) Preparation of Aqueous Dispersion Containing Colloidal Silica A6 In a flask having a capacity of 2000 cm ³ , 120 g of the aqueous dispersion containing colloidal silica A5 prepared above, 1300 g of ion-exchanged water, and 10 g of triethanolamine were put and stirred at 180 rpm. While heating, the temperature was raised to 70 ° C. 280 g of tetramethoxysilane was gradually dropped into this solution to obtain a colloidal silica / methanol dispersion. Next, an operation of removing the methanol content by adding ion-exchanged water to the dispersion at 60 ° C. using an evaporator was performed to remove the methanol in the dispersion, and the aqueous dispersion containing colloidal silica A6 having a solid concentration of 15% was removed. The body was prepared.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 38 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A6 became 1% by mass, and adjusted to pH 2.4. The zeta potential of colloidal silica A6 at that time was +2.6 mV. The zeta potential of the colloidal silica A6 after passing through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was +3.5 mV.

(7) Preparation of Aqueous Dispersion Containing Colloidal Silica A7 In a flask having a capacity of 2000 cm ³ , 120 g of the aqueous dispersion containing colloidal silica A5 prepared above, 1300 g of ion-exchanged water, and 10 g of triethanolamine were stirred and stirred at 180 rpm. While heating, the temperature was raised to 70 ° C. 200 g of tetramethoxysilane was gradually dropped into this solution to obtain a colloidal silica / methanol dispersion. Next, an operation of removing methanol from the dispersion by adding ion-exchanged water to the dispersion at 60 ° C. by an evaporator is performed to remove methanol in the dispersion, and to prepare an aqueous dispersion containing colloidal silica A7 having a solid concentration of 15%. Was prepared.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 33 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A7 became 1% by mass, and adjusted to pH 2.4. The zeta potential of colloidal silica A7 at this time was +1.8 mV. The zeta potential of the colloidal silica A7 after filtration after passing through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was +3 mV.

(8) Preparation of Aqueous Dispersion Containing Colloidal Silica A8 In a flask having a capacity of 2000 cm ³ , 120 g of the aqueous dispersion containing colloidal silica A5 prepared above, 1300 g of ion-exchanged water, and 10 g of triethanolamine were put, and stirred at 180 rpm. While heating, the temperature was raised to 70 ° C. 570 g of tetramethoxysilane was gradually dropped into this solution to obtain a colloidal silica / methanol dispersion. Next, an operation of removing methanol while adding ion-exchanged water to the dispersion at 60 ° C. using an evaporator was performed to remove the methanol in the dispersion and obtain an aqueous dispersion containing colloidal silica A8 having a solid content concentration of 15%. Prepared.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 57 nm when measured. Further, using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model “DT300”), this aqueous dispersion was diluted with ion-exchanged water so that the colloidal silica A8 became 1% by mass,
The zeta potential when adjusted to pH 2.4 was +4.6 mV. The zeta potential of the colloidal silica A8 after passing through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore size of 0.3 μm manufactured by Entegris three times was +3.5 mV.

(9) Preparation of Aqueous Dispersion Containing Colloidal Silica A9 In a flask having a capacity of 2000 cm ³ , 28% aqueous ammonia was added to 1000 g of the aqueous dispersion containing colloidal silica A1 prepared above to adjust the pH to 10.2. A mixture of 19 g of methanol and 0.5 g of 3-aminopropyltrimethoxysilane was added dropwise to this solution over 10 minutes while maintaining the solution temperature at 30 ° C., and the mixture was refluxed at normal pressure for 2 hours to obtain an amino group. An aqueous dispersion containing the modified colloidal silica A9 was obtained.
Using a dynamic light scattering type particle size measuring device (manufactured by Horiba Seisakusho Co., Ltd., model “LB550”), the arithmetic mean diameter of the sample obtained by taking out a part of the aqueous dispersion and diluting with ion-exchanged water is defined as the average particle diameter. It was 65 nm when measured. The aqueous dispersion was diluted with ion-exchanged water so as to have a colloidal silica A9 content of 1% by mass using a zeta potential measurement device (manufactured by Dispersion Technology Inc., model “DT300”) to adjust the pH to 2.4. The zeta potential at that time was +20 mV. The zeta potential of the colloidal silica A9 after filtration through a polypropylene filtration filter (Model No. Planargard PCL0301E6) having a pore diameter of 0.3 μm manufactured by Entegris three times was 10 mV.

4.2. Preparation of Aqueous Dispersion for Chemical Mechanical Polishing A predetermined amount of any of the aqueous dispersions containing colloidal silica prepared above was put into a 5-liter polyethylene bottle, and the amine described in Table 1 or Table 2 was added thereto. The compound, the metal nitrate or the metal sulfate, and the chelating agent were added so as to have the respective contents, and the mixture was sufficiently stirred. Thereafter, nitric acid was added as a pH adjuster, and the pH was adjusted to the values shown in Table 1 or Table 2. Thereafter, the mixture was filtered through a filter having a pore diameter of 0.3 μm to obtain aqueous dispersions for chemical mechanical polishing of Examples 1 to 5 and Comparative Examples 1 to 9. Immediately before performing various evaluation tests described later, 35% by mass of hydrogen peroxide solution was added to the aqueous dispersion for chemical mechanical polishing prepared above so that the amount became 2% by mass in terms of hydrogen peroxide.

4.3. Evaluation method 4.3.1. Evaluation of polishing rate Using the aqueous dispersion for chemical mechanical polishing prepared above, a chemical mechanical polishing test was performed for 1 minute under the following polishing conditions using a tungsten wafer, a silicon dioxide wafer, and a titanium nitride wafer as a body to be polished. The polishing rate was evaluated. The evaluation criteria are as follows. The results are shown in Tables 1 and 2.

<Polishing conditions>
・ Polishing device: Model “ChaMP” manufactured by Tokyo Seimitsu Co.
Polishing pad: Nitta Haas, "IC1000"
・ Chemical mechanical polishing aqueous dispersion supply speed: 200 mL / min ・ Spindle rotation speed: 80 rpm
・ Head rotation speed: 70 rpm
・ Head pressing pressure: 4psi
Polishing rate (nm / min) = (Thickness of each film before polishing-Thickness of each film after polishing) / Polishing time

The thickness of the silicon dioxide film is measured by a model “Analyzer 1512” manufactured by n & k Technology, and the thickness of the tungsten film and the titanium nitride film is measured by a direct current meter using a resistivity measuring machine (manufactured by CDE, model “ResMap”). The resistance was measured by a four-probe method, and calculated from the sheet resistance value and the volume resistivity of the tungsten film or the titanium nitride film by the following equation.
Film thickness (nm) = [volume resistivity (Ω · m) of tungsten film or titanium nitride film ÷ sheet resistance value (Ω)] × 10 ⁹

<Evaluation criteria for tungsten film>
When the polishing rate of the tungsten film is 400 nm / min or more, the polishing rate is sufficiently high, so that high-speed processing can be performed in actual device wafer polishing. 2 was marked with “◎”.
When the polishing rate of the tungsten film is 300 nm / min or more and less than 400 nm / min, the polishing rate is high, and high-speed processing can be performed in actual device wafer polishing. In Table 2, it was described as “○”.
-When the polishing rate was less than 300 nm / min, the polishing rate was too low to be practically useful and judged to be defective. Tables 1 and 2 indicated "x".

<Evaluation criteria for silicon dioxide film>
When the polishing rate of the silicon dioxide film is 40 nm / min or more, the polishing rate is sufficiently high, and high-speed processing can be performed in actual device wafer polishing. In Table 2, it was described as “◎”.
When the polishing rate of the silicon dioxide film is not less than 20 nm / min and less than 40 nm / min, the polishing rate is high, and high-speed processing is possible in actual device wafer polishing. And in Table 2 as “」 ”.
-When the polishing rate of the silicon dioxide film was less than 20 nm / min, the polishing rate was too low to be practically useful and judged to be poor. Tables 1 and 2 indicated "x".

<Evaluation criteria for titanium nitride film>
When the polishing rate of the titanium nitride film is 300 nm / min or more, the polishing rate is sufficiently high, so that high-speed processing can be performed in actual device wafer polishing. In Table 2, it was described as “◎”.
When the polishing rate of the titanium nitride film is 200 nm / min or more and less than 300 nm / min, the polishing rate is high, and high-speed processing is possible in actual device wafer polishing. And in Table 2 as “」 ”.
-When the polishing rate of the titanium nitride film was less than 200 nm / min, the polishing rate was low, so that it was difficult to use it and it was judged to be defective. In Tables 1 and 2, "x" was indicated.

4.3.2. Evaluation of etching rate A test piece obtained by cutting the same tungsten wafer used in the above evaluation of the polishing rate into a piece of 3 cm × 3 cm was immersed in a chemical mechanical polishing aqueous dispersion at a liquid temperature of 60 ° C. for 5 minutes. Then, the etching rate of the tungsten film was measured. The evaluation criteria are as follows. The results are shown in Tables 1 and 2. Note that the etching rate was measured in the same manner as in the evaluation of the polishing rate.
Etching rate (nm / min) = ((weight of tungsten wafer before etching−weight of tungsten wafer after etching) / (tungsten density × tungsten substrate area)) / etching time

<Evaluation criteria>
When the etching rate is 0 nm / min or more and less than 5 nm / min, the etching rate is particularly low, so that the balance with the polishing rate can be easily secured in actual device wafer polishing, and it is practically judged to be particularly good; In Tables 1 and 2, it was described as “◎”.
-If the etching rate is 5 nm / min or more and less than 10 nm / min, the etching rate is rather high, so it is necessary to secure a balance with the polishing rate in actual polishing of the printed circuit board. In Tables 1 and 2, it was indicated as “○”.
-If the etching rate is 10 nm / min or more, the etching rate is too high, and it is difficult to use it practically, and it is judged to be defective.

4.3.3. Evaluation of dispersion stability After preparing the aqueous dispersion for chemical mechanical polishing of each of the examples and comparative examples, the aqueous dispersion for chemical mechanical polishing after standing at 60 ° C. and normal pressure for 5 days was used. The dispersion stability was evaluated by visual observation. As an index of the evaluation of dispersion stability, a dynamic light scattering type particle diameter measuring device (manufactured by HORIBA, Ltd., model “LB550”) is used. When the change from the average particle size after standing for 5 days is less than 5 nm, "◎" is given, when 5 nm or more and less than 10 nm is given as "と し", 10 nm or more or when colloidal sedimentation of colloidal silica abrasive grains occurs. Is set to “×”, and the results are shown in Tables 1 and 2.

4.4. Evaluation Results The compositions, physical properties, and evaluation results of the chemical mechanical polishing aqueous dispersion used in each of the examples and comparative examples are shown in Tables 1 and 2 below.

In Tables 1 and 2, the numerical values of each component represent parts by mass. In each example and each comparative example, the total amount of each component was 100 parts by mass, and the balance was ion-exchanged water.

The following products or reagents were used for each of the components in Tables 1 and 2 above.
<Abrasives>
A1 to A9: colloidal silica A1 to A9 prepared above
<Metal nitrate, metal sulfate>
・ Iron nitrate: manufactured by Tama Chemical Industry Co., Ltd., product name “FN-376”
・ Iron sulfate: manufactured by Fujifilm Wako Pure Chemical Industries, trade name “iron (II) sulfate heptahydrate”
<Amine compound>
-Sodium lauryl amino dipropionate: manufactured by Takemoto Yushi, trade name "Pionin C-158D"
-N-lauroyl-N'-carboxymethyl-N'-hydroxyethylethylenediamine sodium: manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name "Rebon 101-H"
<Chelating agent>
-Malonic acid: trade name "malonic acid" manufactured by Fuso Chemical Industry Co., Ltd.
<Oxidizing agent>
・ Hydrogen peroxide: Fujifilm Wako Pure Chemical Industries, Ltd., trade name “Hydrogen peroxide (30%)”
<PH adjuster>
・ Nitric acid: Kanto Chemical Co., Ltd., trade name “Nitric acid 1.38”

  According to the chemical mechanical polishing aqueous dispersions of Examples 1 to 5, any of the tungsten film, the silicon dioxide film, and the titanium nitride film can be polished at a high speed, and the tungsten film can be effectively etched. It turned out that it can be suppressed. From the above results, the chemical mechanical polishing aqueous dispersions of Examples 1 to 5 were excellent for chemical mechanical polishing of a substrate having at least one of a wiring material, an insulating film material, and a barrier metal material. It is presumed that this can be realized.

  On the other hand, when the chemical mechanical polishing aqueous dispersions of Comparative Examples 1 to 9 were used, any of the polishing rate of the tungsten film and the ability of inhibiting the corrosion of the tungsten film were related to the present invention of Examples 1 to 5. The results were inferior to those of the chemical mechanical polishing aqueous dispersion.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the invention includes configurations substantially the same as the configurations described in the embodiments (for example, a configuration having the same function, method, and result, or a configuration having the same object and effect). Further, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the invention includes a configuration having the same operation and effect as the configuration described in the embodiment or a configuration capable of achieving the same object. The invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

42: slurry supply nozzle, 44: slurry (aqueous dispersion for chemical mechanical polishing), 46: polishing cloth, 48: turntable, 50: substrate, 52: carrier head, 54: water supply nozzle, 56: dresser, 100 ... Polishing equipment

Claims (10)

A method for producing an aqueous dispersion for chemical mechanical polishing, comprising colloidal silica abrasive grains, an amine compound, and at least one selected from the group consisting of metal nitrates and metal sulfates,
A step (I) of hydrolyzing and condensing a silicon alkoxide in an aqueous medium in which a tertiary amine compound is present;
After the step (I), a step (IV) of dropping silicon alkoxide into the aqueous medium to grow colloidal silica abrasive grains having a zeta potential of +1 mV or more and +5 mV or less;
A step (V) of adding an amine compound and at least one selected from the group consisting of metal nitrates and metal sulfates to the aqueous medium after the step (IV);
A method for producing an aqueous dispersion for chemical mechanical polishing, comprising:   The chemical mechanical polishing aqueous dispersion according to claim 1, further comprising a step (II) of concentrating the aqueous medium to remove an alcohol component after the step (I) and before the step (IV). Production method.   3. The chemical mechanical polishing aqueous system according to claim 1, further comprising a step (III) of adding a tertiary amine to the aqueous medium after the step (I) and before the step (IV). A method for producing a dispersion.   The method for producing an aqueous dispersion for chemical mechanical polishing according to any one of claims 1 to 3, further comprising a step (VI) of adding hydrogen peroxide after the step (V).   5. The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 4, wherein the aqueous dispersion is for polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride. A method for producing an aqueous dispersion for chemical mechanical polishing according to the above. (A) colloidal silica abrasive grains having a permanent positive charge of +1 mV or more and +5 mV or less,
(B) at least one selected from the group consisting of metal nitrates and metal sulfates;
(C) at least one selected from the group consisting of amine compounds and salts thereof,
(D) a chelating agent other than the component (C),
And an aqueous dispersion for chemical mechanical polishing having a pH of 1 or more and 3 or less.   The chemical mechanical polishing aqueous dispersion according to claim 6, wherein a tertiary amine compound is contained in the colloidal silica abrasive grains.   The chemical mechanical polishing aqueous dispersion according to claim 7, wherein the tertiary amine compound is included in the colloidal silica abrasive grains.   The chemical mechanical polishing aqueous dispersion according to any one of claims 6 to 8, which is used for polishing a substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride.   A substrate containing at least one selected from the group consisting of tungsten, silicon dioxide, and titanium nitride is polished using the chemical mechanical polishing aqueous dispersion according to any one of claims 6 to 9. A chemical mechanical polishing method including a step.

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