JP2017061612A - Composition for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion for chemical mechanical polishing and a chemical mechanical polishing method for polishing a surface to be treated of a workpiece such as a semiconductor wafer provided with a wiring layer containing a metal while reducing the corrosion of a tungsten film surface without decreasing the polishing speed.SOLUTION: There is provided a composition for chemical mechanical polishing which comprises (A) a compound represented by the following general formula (1) or a salt thereof, (B) a dispersion medium containing water, (C) abrasive grains and (D) an oxidizing agent. (In the formula, R1 represents a group having a substituted or unsubstituted alkyl group having 8 or more carbon atoms, R2 represents a hydrogen atom or an organic group having 1 to 3 carbon atoms which has a hydroxy group or a carboxyl group, R3 represents an alkylene group having 1 to 3 carbon atoms.)SELECTED DRAWING: None

Description

  The present invention relates to a chemical mechanical polishing composition and a chemical mechanical polishing method.

  2. Description of the Related Art In recent years, with the increase in definition of a semiconductor device, the miniaturization of a wiring layer composed of wirings, plugs, and the like formed in the semiconductor device has been advanced. Along with this, a technique of planarizing the wiring layer by chemical mechanical polishing (hereinafter also referred to as “CMP”) is used. As this technique, for example, a conductor metal such as aluminum, copper, or tungsten is deposited in a fine groove or hole provided in an insulating film such as silicon oxide on a semiconductor substrate by a method such as sputtering or plating. Thereafter, a damascene process is known in which an excessively laminated metal film is removed by CMP, and the metal is left only in a minute groove or hole (see, for example, Patent Document 1).

  In this process, tungsten having excellent embedding property is used as a material such as a plug for electrically connecting the wirings in the vertical and vertical directions. In the chemical mechanical polishing for forming the tungsten plug, a first polishing process for mainly polishing the tungsten layer provided on the insulating film, and a second polishing for polishing the tungsten plug, a barrier metal film such as titanium, and the insulating film. Processing steps are performed in sequence.

  With regard to chemical mechanical polishing of such a tungsten layer and a tungsten plug (hereinafter also referred to as “tungsten film”), for example, in Patent Document 2, it is used in a stage prior to finish polishing corresponding to the first polishing process. Colloidal silica, etc. for the purpose of preventing surface roughness after polishing due to high polishing rate and high reactivity between amine compound as polishing accelerator and silicon as a composition for semiconductor polishing A polishing composition comprising a basic low-molecular compound such as an abrasive compound, an amine compound, and a water-soluble polymer compound containing a nitrogen-containing group such as polyethyleneimine is disclosed.

Patent Document 3 discloses a chemical mechanical polishing composition containing a tungsten etching agent such as an oxidizing agent, a tungsten etching inhibitor such as a specific polymer containing nitrogen atoms present in an amount of 1 to 1,000 ppm, and water. A chemical mechanical polishing method for a substrate containing tungsten that is polished using an object is disclosed. The chemical mechanical polishing composition used in this polishing method includes, as optional components, an abrasive such as colloidal silica, monopersulfate (SO ₅ ²⁻ ), dipersulfate (S ₂ O ₈ ²⁻ ) And the like.

Special table 2002-518845 gazette JP 2007-19093 A Special table 2008-503875 gazette

  However, an aqueous dispersion for polishing a tungsten film that can achieve a reduction in corrosion of the surface to be polished while maintaining a high polishing rate has not been obtained.

Accordingly, some aspects of the present invention solve the above-described problems, and in a semiconductor device manufacturing process, a target object such as a semiconductor wafer provided with a wiring layer containing a metal such as tungsten, particularly the target object. A chemical mechanical polishing composition for polishing a surface to be processed in which a tungsten film and an insulating film such as a silicon oxide film coexist while reducing corrosion of the tungsten film surface without reducing the polishing rate, and A chemical mechanical polishing method is provided.

  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 the following aspects or application examples.

（上記式（１）中、Ｒ１は置換もしくは非置換の炭素数８以上のアルキル基を有する基であり、Ｒ２は水素原子、水酸基又はカルボキシル基を有する炭素数１〜３の有機基であり、Ｒ３は炭素数１〜３のアルキレン基を表す。） [Application Example 1]
One aspect of the chemical mechanical polishing composition according to the present invention is:
(A) a compound represented by the following general formula (1) or a salt thereof;
(B) a dispersion medium containing water;
(C) abrasive grains;
(D) An oxidizing agent is contained.

(In the above formula (1), R1 is a substituted or unsubstituted group having an alkyl group having 8 or more carbon atoms, R2 is a C1-3 organic group having a hydrogen atom, a hydroxyl group or a carboxyl group, R3 represents an alkylene group having 1 to 3 carbon atoms.)

[Application Example 2]
In the chemical mechanical polishing composition of Application Example 1,
(D) It can contain at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ , and Cu ²⁺ .

[Application Example 3]
In the chemical mechanical polishing composition of Application Example 1 or Application Example 2,
The ratio (A) / (D) of the component (A) and the component (D) may be 0.005 to 0.1.

[Application Example 4]
In the chemical mechanical polishing composition according to any one of Application Examples 1 to 3,
The pH can be 1.5-3.5.

[Application Example 5]
In the chemical mechanical polishing composition of any one of Application Examples 1 to 4,
It can be for polishing at least one substrate selected from the group consisting of tungsten and tungsten alloys.

[Application Example 6]
One aspect of the chemical mechanical polishing method according to the present invention is:
Using the chemical mechanical polishing composition according to any one of Application Example 1 to Application Example 5, a target object provided with a wiring layer containing a metal is polished.

According to the chemical mechanical polishing composition of the present invention, in a semiconductor device manufacturing process, an object to be processed such as a semiconductor wafer provided with a wiring layer containing a metal such as tungsten, in particular, an oxidation of the tungsten film of the object to be processed. A surface to be processed in which an insulating film such as a silicon film coexists can be polished while reducing corrosion of the tungsten film surface without reducing the polishing rate.

It is sectional drawing which showed typically the to-be-processed object suitable for use of the chemical mechanical polishing method which concerns on this Embodiment. It is the perspective view which showed typically the chemical mechanical polishing apparatus suitable for use of the chemical mechanical polishing method which concerns on this Embodiment

  Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, Various modifications implemented in the range which does not change the summary of this invention are also included.

（上記式（１）中、Ｒ１は置換もしくは非置換の炭素数８以上のアルキル基を有する基であり、Ｒ２は水素原子、水酸基又はカルボキシル基を有する炭素数１〜３の有機基であり、Ｒ３は炭素数１〜３のアルキレン基を表す。） 1. Chemical mechanical polishing composition A chemical mechanical polishing composition according to an embodiment of the present invention includes (A) a compound represented by the following general formula (1) or a salt thereof, and (B) a dispersion medium containing water. , (C) abrasive grains and (D) an oxidizing agent. Hereinafter, each component contained in the chemical mechanical polishing composition according to the present embodiment will be described.

(In the above formula (1), R1 is a substituted or unsubstituted group having an alkyl group having 8 or more carbon atoms, R2 is a C1-3 organic group having a hydrogen atom, a hydroxyl group or a carboxyl group, R3 represents an alkylene group having 1 to 3 carbon atoms.)

  The chemical mechanical polishing composition according to the present embodiment is used, for example, for polishing a target object provided with a wiring layer containing a metal such as tungsten, as will be described later.

（上記式（１）中、Ｒ１は置換もしくは非置換の炭素数８以上のアルキル基を有する基であり、Ｒ２は水素原子、水酸基又はカルボキシル基を有する炭素数１〜３の有機基であり、Ｒ３は炭素数１〜３のアルキレン基を表す。） 1.1. (A) Component The chemical mechanical polishing composition according to the present embodiment contains (A) a compound represented by the following general formula (1) or a salt thereof.

(In the above formula (1), R1 is a substituted or unsubstituted group having an alkyl group having 8 or more carbon atoms, R2 is a C1-3 organic group having a hydrogen atom, a hydroxyl group or a carboxyl group, R3 represents an alkylene group having 1 to 3 carbon atoms.)

In the chemical mechanical polishing composition according to the present embodiment, the effect of the component (A) is not necessarily clear, but is estimated as follows. That is, the component (A) has a function as a surfactant, an ionic unit containing a nitrogen atom is adsorbed on the metal surface by interaction with the metal surface of the object to be treated, and the long chain unit of R1 is described later. (D) Suppresses chemical reactions caused by oxidizing agents and the like. As a result, the component (A) acts as a corrosion inhibitor for the metal surface that is the object to be processed, and forms a multilayer anticorrosion film on the surface to be processed on which the wiring layer containing a metal such as tungsten is provided. In this way, the component (A) has an action of adjusting the balance of oxidizing power and the like by the chemical mechanical polishing composition (C) abrasive grains and (D) oxidizing agent, etc., so without reducing the polishing rate, It is considered that the surface to be processed can be polished while reducing the corrosion of the surface to be processed.

  Examples of the group having a substituted or unsubstituted alkyl group having 8 or more carbon atoms in R1 in the general formula (1) include, for example, a linear or branched alkyl group having 8 or more carbon atoms, and a group having 8 or more carbon atoms. An amide group having an alkyl group which may be linear or branched, an amino group having an alkyl group which may be linear or branched having 8 or more carbon atoms, an alkyl group having an alkyl group which may be linear or branched having 8 or more carbon atoms, etc. Can be mentioned. Among these, from the viewpoint of a corrosion inhibitor, a linear alkyl group having 8 or more carbon atoms, an amide group having a linear alkyl group having 8 or more carbon atoms, and an amino group having a linear alkyl group having 8 or more carbon atoms are preferable. . When the number of carbon atoms is 8 or more, the balance of the oxidizing power of the composition is adjusted, and the effect of suppressing the chemical reaction by the (D) oxidizing agent is high.

  R2 in the general formula (1) is a C 1-3 organic group having a hydrogen atom, a hydroxyl group or a carboxyl group. As a C1-C3 organic group which has a hydroxyl group or a carboxyl group, a C1-C3 hydroxyl group and a C1-C3 carboxyl group can be mentioned. As a C1-C3 hydroxyl group, a hydroxyethyl group and a hydroxymethyl group are preferable. As a C1-C3 carboxyl group, a carboxyethyl group and a carboxymethyl group are preferable.

  In particular, the compound represented by the general formula (1) or a salt thereof is at least one selected from the group consisting of sodium laurylaminopropionate, sodium laurylaminodipropionate, sodium lauroamphoacetate, and sodium cocoamphoacetate. It is preferable that When these compounds are used, the surface to be processed can be polished while reducing the corrosion of the surface to be processed without further reducing the polishing rate. The compounds exemplified above may be used alone or in combination of two or more.

  (A) The content rate of a component is 0.0001 mass% or more and 0.5 mass% or less with respect to the total mass of the composition for chemical mechanical polishing, Preferably it is 0.001 mass% or more and 0.1 mass% or less, More preferably, it is 0.01 mass% or more and 0.05 mass% or less. When the content ratio of the component (A) is in the above range, the surface to be processed can be polished while reducing the corrosion of the surface to be processed without reducing the polishing rate.

1.2. (B) Dispersion medium The chemical mechanical polishing composition according to the present embodiment contains water as the (B) dispersion medium. (B) Although a dispersion medium will not be limited about other components if it contains water, It is preferable that it is a solvent which does not affect the oxidizing power of the composition for chemical mechanical polishing. Examples of the components other than water contained in the dispersion medium include alcohols, organic solvents having compatibility with water, and the like. (B) As a dispersion medium, it is preferable to use water or a mixed medium of water and alcohol, and more preferably only water.

  (B) When the dispersion medium is a mixed medium containing water and a dispersion medium other than water, the content ratio of water is 80% by mass or more and 99% by mass or less, preferably based on the total mass of the chemical mechanical polishing composition. Is 85 mass% or more and 98 mass% or less, More preferably, it is 90 mass% or more and 98 mass% or less. When the water content is within the above range, the surface to be processed can be polished while reducing the corrosion of the surface to be processed without reducing the polishing rate.

1.3. (C) Abrasive Grain The chemical mechanical polishing composition according to the present embodiment further contains (C) an abrasive grain. (C) As an abrasive grain, inorganic particles, such as a silica, a ceria, an alumina, a zirconia, a titania, are mentioned, for example.

  Examples of the silica particles include colloidal silica and fumed silica. Among these, colloidal silica is preferably used. Colloidal silica is preferably used from the viewpoint of reducing polishing defects such as scratches, and for example, those produced by the method described in JP-A-2003-109921 can be used. Also, JP 2010-269985A, J. Org. Ind. Eng. Chem. , Vol. 12, no. 6, (2006) 911-917 or the like, surface-modified colloidal silica may be used.

  In particular, cationically modified colloidal silica having a cationic group introduced on the surface of colloidal silica is excellent in stability under acidic conditions, and thus is preferably used in the present invention. Examples of the method for introducing a cationic group on the surface of colloidal silica include a method for modifying a silane coupling agent having a functional group that can be chemically converted into a cationic group on the surface of colloidal silica. As such silane coupling agents, aminopropyltrimethoxysilane, (aminoethyl) aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, aminobutyltriethoxysilane Etc.

  Moreover, you may use the sulfonic acid modification colloidal silica by which the sulfonic acid group was introduce | transduced into the surface of colloidal silica. As a method for introducing a sulfonic acid group to the surface of colloidal silica, a silane coupling agent having a functional group that can be chemically converted to a sulfonic acid group is modified on the surface of colloidal silica, and then the functional group is converted to a sulfonic acid group. The method of converting into is mentioned. Examples of such silane coupling agents include silane coupling agents having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; bis (3-triethoxy And silane coupling agents having a sulfide group such as (silylpropyl) disulfide. It can be converted into a sulfonic acid group by oxidizing the mercapto group or sulfide group of the silane coupling agent modified on the surface of the colloidal silica.

  (C) The content ratio of the abrasive grains is 0.1% by mass or more and 10% by mass or less, preferably 0.3% by mass or more and 8% by mass or less, more preferably based on the total mass of the chemical mechanical polishing composition. It is 0.5 mass% or more and 5 mass% or less. (C) When the content ratio of the abrasive grains is within the above range, a practical polishing rate can be obtained while reducing the corrosion of the surface to be processed having a tungsten film or the like.

1.4. (D) Oxidizing agent The chemical mechanical polishing composition according to the present embodiment contains (D) an oxidizing agent. In the chemical mechanical polishing composition according to the present embodiment, (D) by containing an oxidizing agent, the surface to be processed provided with a wiring layer containing a metal such as tungsten is oxidized to form a complex with the polishing liquid component. By promoting the crystallization reaction, there is an effect of creating a fragile modified layer on the surface to be processed and facilitating polishing.

Examples of (D) oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, ferric nitrate, diammonium cerium nitrate, hypochlorous acid, ozone, potassium periodate, and peracetic acid. These (D) oxidizing agents may be used individually by 1 type, and may be used in combination of 2 or more type. Further, among these (D) oxidizing agents, it is preferable to use ammonium persulfate or hydrogen peroxide as the (D) oxidizing agent in consideration of oxidizing power, compatibility with the protective film, ease of handling, and the like.

  (D) The content ratio of the oxidizing agent is 0.1% by mass or more and 15% by mass or less, preferably 0.5% by mass or more and 10% by mass or less, more preferably with respect to the total mass of the chemical mechanical polishing composition. It is 1 mass% or more and 5 mass% or less.

  The ratio (A) / (D) of the component (A) to the component (D) is preferably 0.005 to 0.1, and more preferably 0.01 to 0.05. When the ratio of the component (A) to the component (D) is within the above range, the surface to be processed can be polished while reducing the corrosion of the surface to be processed without reducing the polishing rate.

1.5. (E) Metal ion The chemical mechanical polishing composition according to this embodiment preferably contains (E) at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ , and Cu ²⁺ . In the chemical mechanical polishing composition according to the present embodiment, when (E) a metal ion is further contained, the surface to be processed provided with a wiring layer containing a metal such as tungsten is oxidized to produce a polishing liquid component. By promoting the complexing reaction, a fragile modified layer is created on the surface to be processed, and it has the effect of facilitating polishing.

(E) The compound containing at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ , and Cu ²⁺ may be either an inorganic acid iron salt or an organic acid iron salt. For example, iron nitrate (II or III), iron sulfate (II or III), ammonium iron sulfate (III), iron (III) perchlorate, iron (III) chloride, iron (III) citrate, iron iron (III) citrate, Shu Examples include ammonium iron (III), copper nitrate (II), copper sulfate (II), and the like. These (E) metal ions may be used individually by 1 type, and may be used in combination of 2 or more type. Of these (E) metal ions, iron nitrate, iron sulfate, copper nitrate, and copper sulfate are preferred in view of oxidizing power, compatibility with the protective film, ease of handling, and the like.

  The content of metal ions is preferably 0.0001% by mass or more and 0.1% by mass or less, more preferably 0.0005% by mass or more and 0.01% by mass with respect to the total mass of the chemical mechanical polishing composition. %, Particularly preferably 0.001% by mass or more and 0.005% by mass or less.

1.6. Other Additives The chemical mechanical polishing composition according to the present embodiment further contains a chelating agent, a water-soluble polymer, a pH adjuster, or a compound other than the compound represented by the general formula (1) as necessary. You may add additives, such as surfactant and a corrosion inhibitor. Hereinafter, each additive will be described.

1.6.1. (F) Chelating agent The chemical mechanical polishing composition according to this embodiment may contain (F) a chelating agent. By adding (F) a chelating agent to the chemical mechanical polishing composition according to the present embodiment, the surface to be processed provided with a wiring layer containing a metal such as tungsten is oxidized to form a complex with the polishing liquid component. It has the effect of facilitating the chemical reaction, creating a fragile modified layer on the surface to be treated, and making the surface to be treated easy to polish.

Examples of chelating agents include malonic acid, phthalic acid, citric acid, succinic acid, glutaric acid, adipic acid, adenine, histidine, ethylenediamine, 1,2,4-triazole, glycine, 1-hydroxyethane-1,1. -Diphosphonic acid etc. are mentioned. These chelating agents may be used individually by 1 type, and may be used in combination of 2 or more type. Of these chelating agents, phthalic acid, malonic acid, adipic acid, adenine, and histidine are preferably used in consideration of oxidizing power, compatibility with a protective film, ease of handling, and the like.

  The addition amount of the chelating agent is preferably 1% by mass or less, more preferably 0.001% by mass or more and 0.1% by mass or less, with respect to the total mass of the chemical mechanical polishing composition.

1.6.2. (G) Water-soluble polymer The chemical mechanical polishing composition according to this embodiment may contain (G) a water-soluble polymer. (G) The water-soluble polymer has a function of reducing polishing friction by adsorbing to the surface of the surface to be polished. Thus, by adding the (G) water-soluble polymer to the chemical mechanical polishing composition according to the present embodiment, the occurrence of dishing or corrosion may be suppressed in some cases.

  Examples of the water-soluble polymer include polyacrylamide, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, polyethyleneimine, polyallylamine, and hydroxyethyl cellulose.

  The addition amount of the water-soluble polymer is preferably 0.005% by mass or less, more preferably 0.0001% by mass or more and 0.001% by mass or less, with respect to the total mass of the chemical mechanical polishing composition. .

  The amount of the water-soluble polymer added can be adjusted so that the chemical mechanical polishing composition has a viscosity of less than 10 mPa · s. When the viscosity of the chemical mechanical polishing composition exceeds 10 mPa · s, the polishing rate may decrease, and the viscosity may become too high to supply the chemical mechanical polishing composition stably on the polishing cloth. . As a result, an increase in the temperature of the polishing cloth, uneven polishing (deterioration of in-plane uniformity), and the like may occur, resulting in variations in polishing rate and dishing.

1.6.3. pH adjuster The chemical mechanical polishing composition according to the present embodiment may contain a pH adjuster. Examples of the pH adjuster include acidic compounds such as maleic acid, nitric acid, sulfuric acid, and phosphoric acid. The pH of the chemical mechanical polishing composition according to the present embodiment is not particularly limited, but is preferably 1.5 or more and 3.5 or less. When the pH is within the above range, the surface to be processed in which the tungsten film and the insulating film such as the silicon oxide film coexist can be polished while reducing the corrosion of the surface to be processed without reducing the polishing rate. Further, the storage stability of the chemical mechanical polishing composition is improved.

  What is necessary is just to adjust suitably content of a pH adjuster so that it may become the said pH, for example, Preferably it is 1 mass% or less with respect to the total mass of the composition for chemical mechanical polishing, More preferably, it is 0.001. It is not less than mass% and not more than 0.1 mass%.

1.6.4. Surfactant To the chemical mechanical polishing composition according to the present embodiment, if necessary, a surfactant other than the compound represented by the general formula (1) may be added. The surfactant has an effect of imparting an appropriate viscosity to the chemical mechanical polishing composition. The viscosity of the chemical mechanical polishing aqueous dispersion is preferably adjusted to be 0.5 mPa · s or more and less than 10 mPa · s at 25 ° C.

  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, sulfonate, sulfate ester salt, phosphate ester salt and the like. Examples of the carboxylate include fatty acid soap and alkyl ether carboxylate. Examples of the sulfonate include alkylbenzene sulfonate, alkyl naphthalene sulfonate, and α-olefin sulfonate. Examples of the sulfate ester salt include higher alcohol sulfate ester salts and alkyl sulfate ester salts. Examples of phosphate esters include alkyl phosphate esters.

  Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts.

  Examples of nonionic surfactants include ether type surfactants, ether ester type surfactants, ester type surfactants, and acetylene type surfactants. Examples of the ether ester type surfactant include polyoxyethylene ether of glycerin ester. Examples of the ester type surfactant include polyethylene glycol fatty acid ester, glycerin ester, sorbitan ester and the like. Examples of the acetylene-based surfactant include acetylene alcohol, acetylene glycol, ethylene oxide adduct of acetylene diol, and the like.

  These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the surfactant is preferably 1% by mass or less, more preferably 0.001 to 0.1% by mass with respect to the total mass of the chemical mechanical polishing composition. When the addition amount of the surfactant is within the above range, a smooth polished surface can be obtained after polishing and removing the tungsten film and the insulating film such as a silicon oxide film.

1.6.5. Corrosion-proofing agent You may add a corrosion-proofing agent to the chemical mechanical polishing composition which concerns on this Embodiment further as needed. Examples of the corrosion inhibitor include benzotriazole and derivatives thereof. Here, the benzotriazole derivative means one obtained by substituting one or more hydrogen atoms of benzotriazole with, for example, a carboxyl group, a methyl group, an amino group, a hydroxyl group or the like. Examples of the benzotriazole derivative include 4-carboxylbenzotriazole and its salt, 7-carboxybenzotriazole and its salt, benzotriazole butyl ester, 1-hydroxymethylbenzotriazole, 1-hydroxybenzotriazole and the like.

  The addition amount of the corrosion inhibitor is preferably 1% by mass or less, more preferably 0.001% by mass or more and 0.1% by mass or less, with respect to the total mass of the chemical mechanical polishing composition.

1.7. Application As described above, the chemical mechanical polishing composition according to the present embodiment contains the component (A), so that the balance of the oxidizing power and the like of the chemical mechanical polishing composition is adjusted, and the chemical mechanical polishing composition is drastically covered. Corrosion suppression effect on the treated surface is increased. For this reason, the chemical mechanical polishing composition according to the present embodiment is suitable as at least one base polishing composition selected from the group consisting of tungsten and a tungsten alloy metal. For example, in a semiconductor device manufacturing process, an object to be processed such as a semiconductor wafer provided with a wiring layer containing a metal such as tungsten, particularly an object such as a tungsten film of the object to be processed and an insulating film such as a silicon oxide film. It is suitable as an abrasive for polishing the treated surface while maintaining the polishing rate and suppressing corrosion of the tungsten film surface.

1.8. Method for Preparing Chemical Mechanical Polishing Composition The chemical mechanical polishing composition according to the present embodiment can be prepared by dissolving or dispersing each component described above in (B) a dispersion medium containing water. The method for dissolving or dispersing is not particularly limited, and any method may be applied as long as it can be uniformly dissolved or dispersed. Further, the mixing order and mixing method of the components described above are not particularly limited.

  In addition, the chemical mechanical polishing composition according to the present embodiment can be prepared as a concentrated type stock solution and diluted with a (B) dispersion medium containing water at the time of use.

2. Chemical mechanical polishing method The chemical mechanical polishing method according to the present embodiment is provided with a wiring layer containing a metal such as tungsten constituting the semiconductor device, using the chemical mechanical polishing aqueous dispersion according to the present invention described above. The object to be processed is polished. Hereinafter, a specific example of the chemical mechanical polishing method according to the present embodiment will be described in detail with reference to the drawings.

2.1. FIG. 1 is a cross-sectional view schematically showing a target object suitable for use in the chemical mechanical polishing method according to the present embodiment. The target object 100 is formed through the following steps (1) to (4).
(1) First, the silicon substrate 10 is prepared. A functional device such as a transistor (not shown) may be formed on the silicon substrate 10.
(2) Next, a silicon oxide film 12 is formed on the silicon substrate 10 by using a CVD method or a thermal oxidation method.
(3) Next, the silicon oxide film 12 is patterned. Using this as a mask, for example, an etching method is applied to form the recess 20 for wiring in the silicon oxide film 12.
(4) Next, when the tungsten film 14 is deposited by the CVD method so as to fill the recess 20 for wiring, the workpiece 100 is obtained.

2.2. Polishing Step Using the above-described chemical mechanical polishing composition, the tungsten film 14 deposited on the silicon oxide film 12 of the object 100 is polished and removed, and then a tungsten plug, a barrier metal film such as titanium, and an insulating material. Polish the membrane. According to the chemical mechanical polishing method according to the present embodiment, by using the chemical mechanical polishing composition described above, the surface to be processed on which a tungsten film and an insulating film such as a silicon oxide film coexist is reduced in the polishing rate. Therefore, polishing can be performed while reducing the corrosion of the tungsten film surface.

2.3. Chemical Mechanical Polishing Device For the above polishing process, for example, a chemical mechanical polishing device 200 as shown in FIG. 2 can be used. FIG. 2 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. In the above polishing step, the carrier head that holds the semiconductor substrate 50 while supplying the slurry (chemical mechanical polishing composition) 44 from the slurry supply nozzle 42 and rotating the turntable 48 to which the polishing cloth 46 is attached. This is done by bringing 52 into contact. In FIG. 2, the water supply nozzle 54 and the dresser 56 are also shown.

The pressing pressure of the carrier head 52 can be selected within a range of 10 to 1,000 hPa, and preferably 30 to 500 hPa. Moreover, the rotation speed of the turntable 48 and the carrier head 52 can be suitably selected within the range of 10 to 400 rpm, and preferably 30 to 150 rpm. The flow rate of the slurry (chemical mechanical polishing composition) 44 supplied from the slurry supply nozzle 42 can be selected within the range of 10 to 1,000 mL / min, and preferably 50 to 400 mL / min.

  As a commercially available polishing apparatus, for example, “EPO-112”, “EPO-222” manufactured by Ebara Manufacturing Co., Ltd .; “LGP-510”, “LGP-552” manufactured by Lappmaster SFT, manufactured by Applied Materials , “Mirra”, “Reflexion” and the like.

3. Examples Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples. “Part” and “%” in Examples and Comparative Examples are based on mass unless otherwise specified.

3.1. Preparation of chemical mechanical polishing composition <Example 1>
Colloidal silica aqueous dispersion PL-3 (manufactured by Fuso Chemical Co., Ltd.) as the abrasive grains (C) is equivalent to 1.5% by mass in terms of silica with respect to the total mass of the chemical mechanical polishing composition. Into a polyethylene container so that the final total components are 100% by mass, and ion-exchanged water is calculated, and the final pH is calculated to be 2.5. Nitric acid was added as a modifier. Furthermore, 0.030 mass% of N-lauroyl-N′-carboxymethyl-N′-hydroxyethylethylenediamine sodium (manufactured by Sanyo Chemical Industries, Ltd., trade name Levon 101-H), 112 ppm of phthalic acid, 35 mass% excess Hydrogen oxide water was added to each of 2% by mass in terms of hydrogen peroxide and stirred for 15 minutes to obtain a chemical mechanical polishing composition of Example 1. The resulting chemical mechanical polishing composition had a pH of 2.5.

<Examples 2 to 14 and Comparative Examples 1 to 10>
A chemical mechanical polishing composition was prepared in the same manner as in Example 1 except that the compositions shown in Tables 1 and 2 were used. In Examples 2-14 and Comparative Examples 2-10, (C) PL-3C used as abrasive grains has a particle diameter similar to that of colloidal silica water dispersion PL-3, and is modified with cationic modified colloidal silica water. Body (manufactured by Fuso Chemical Co., Ltd.). Also, sodium laurylaminopropionate is manufactured by Taiko Yushi Chemical Co., Ltd., trade name: Typol Soft LAP-10, and laurylamino dipropionic acid is manufactured by Taiko Yushi Chemical Co., Ltd., trade name: Typol Soft LAP-30. Using.

3.2. Evaluation method 3.2.1. Evaluation of Etching Rate A tungsten cut wafer (3 × 3 cm) was immersed in the obtained chemical mechanical polishing composition at 45 ° C. for 10 minutes, washed with running water for 10 seconds and dried. The change in thickness was measured, and the change in thickness was divided by 10 to calculate the tungsten etching rate of the chemical mechanical polishing composition. The evaluation criteria for the etching test are as follows.
A: 0 nm / min or more and less than 2 nm / min ○: 2 nm / min or more and less than 5 nm / min Δ: 5 nm / min or more and less than 10 nm / min ×: 10 nm / min or more

3.2.2. Evaluation of Polishing Speed Using a lap master SFT, model “LM-15C” as a polishing apparatus, Rodel Nitta, “IC1000 / K-Groove” as a polishing pad, a platen rotation speed of 90 rpm, a head rotation speed of 90 rpm The surface of the tungsten wafer specimen as the object to be polished was subjected to chemical mechanical polishing (CMP) for 1 minute under polishing conditions of a head pressing pressure of 3 psi and a chemical mechanical polishing aqueous dispersion supply rate of 100 mL / min. Next, about the tungsten wafer test piece cut into 3 × 3 cm, which is an object to be polished, the film thickness is measured in advance using a metal film thickness meter “RG-5” manufactured by NPS, and chemical mechanical polishing treatment is performed as 1 Conducted for a minute. The thickness of the test specimen after polishing was measured in the same manner, and the difference in film thickness before and after polishing, that is, the thickness decreased by the chemical mechanical polishing treatment was calculated. The polishing rate was calculated from the reduced film thickness and polishing time. The evaluation criteria for the polishing rate are as follows.
◎: 200 nm / min or more ○: 100 nm / min or more and less than 200 nm / min Δ: 10 nm / min or more and less than 100 nm / min ×: less than 10 nm / min

3.2.3. Evaluation of Corrosion A tungsten cut wafer (1 × 1 cm) was immersed in the obtained chemical mechanical polishing composition for 1 hour, washed with running water for 10 seconds and dried, and then surface corrosion was observed with a scanning electron microscope. The evaluation criteria for corrosion are as follows.
○: No change in surface shape due to corrosion was observed compared to before immersion. ×: Part or the entire surface was corroded compared to before immersion.

3.2.4. Evaluation of Storage Stability The obtained chemical mechanical polishing composition is concentrated twice, and the particle diameter after 2 weeks is heated with a dynamic light scattering particle size distribution measuring device under the initial particle diameter and 60 ° C. heating. Measurements were made and the presence or absence of settling of the abrasive grains was confirmed. The evaluation criteria for storage stability are as follows.
○: No change in particle size was observed compared to the initial particle size. Δ: Change in particle size was observed compared to the initial particle size, but did not lead to visual grain settling. ×: Change in particle size was observed compared to the initial particle size, and visual grain settling was also observed.

3.3. Evaluation results Compositions of chemical mechanical polishing compositions obtained in Examples 1 to 14 and evaluation results are shown in Table 1 below. Compositions of chemical mechanical polishing compositions obtained in Comparative Examples 1 to 10 and evaluation The results are shown in Table 2 below.

As is clear from Tables 1 and 2, the chemical mechanical polishing composition according to the present invention shown in Examples 1 to 14 was compared with Comparative Examples 1 to 10 in the tungsten film and silicon oxide of the object to be processed. It was possible to polish the surface to be processed in which an insulating film such as a film coexists without reducing the polishing rate while reducing the corrosion of the tungsten film surface. In particular, in Examples 2 to 14 to which (E) the metal salt was added, both higher maintenance of the polishing rate and reduction in corrosion of the tungsten film surface were possible as compared with Examples 1 and 2. In Comparative Example 8, since the pH was higher than 3.5, Fe ²⁺ was precipitated as iron hydroxide, and thus could not be evaluated. In Comparative Example 5 using lauryldimethylaminoacetic acid betaine having a structure similar to component (A) but having more carbon atoms bonded to nitrogen atoms than component (A), a high polishing rate was obtained. Since it is a quaternary ammonium compound, storage stability was not obtained.

  The present invention is not limited to the above embodiment, and various modifications can be made. The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). The present invention also includes a configuration in which a non-essential part of the configuration described in the above embodiment is replaced with another configuration. Furthermore, the present invention includes a configuration that achieves the same effects as the configuration described in the above embodiment or a configuration that can achieve the same object. Furthermore, the present invention includes a configuration obtained by adding a known technique to the configuration described in the above embodiment.

DESCRIPTION OF SYMBOLS 10 ... Silicon substrate, 12 ... Silicon oxide film, 14 ... Tungsten film, 20 ... Recess for wiring, 42 ... Slurry supply nozzle, 44 ... Slurry (chemical mechanical polishing composition), 46 ... Polishing cloth, 48 ... Turntable, DESCRIPTION OF SYMBOLS 50 ... Semiconductor substrate, 52 ... Carrier head, 54 ... Water supply nozzle, 56 ... Dresser, 100 ... To-be-processed object, 200 ... Chemical mechanical polishing apparatus

Claims (6)

(A) a compound represented by the following general formula (1) or a salt thereof;
(B) a dispersion medium containing water;
(C) abrasive grains;
(D) Chemical mechanical polishing composition containing an oxidizing agent.

(In the above formula (1), R1 is a substituted or unsubstituted group having an alkyl group having 8 or more carbon atoms, R2 is a C1-3 organic group having a hydrogen atom, a hydroxyl group or a carboxyl group, R3 represents an alkylene group having 1 to 3 carbon atoms.) The chemical mechanical polishing composition according to claim 1, further comprising (E) at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ and Cu ²⁺ .   The chemical mechanical polishing composition according to claim 1 or 2, wherein a ratio (A) / (D) of the component (A) to the component (D) is 0.005 to 0.1.   The chemical mechanical polishing composition according to any one of claims 1 to 3, wherein the pH is 1.5 to 3.5.   The chemical mechanical polishing composition according to any one of claims 1 to 4, which is used for polishing at least one substrate selected from the group consisting of tungsten and a tungsten alloy metal.   A chemical mechanical polishing method for polishing a target object provided with a wiring layer containing a metal, using the chemical mechanical polishing composition according to any one of claims 1 to 5.

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