JP2018107294A - Chemical mechanical polishing composition and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for chemical mechanical polishing useful for manufacturing a semiconductor device, which can realize good polishing characteristics while suppressing corrosion of a cobalt film, and a chemical mechanical polishing method using the same. A composition for chemical mechanical polishing according to the present invention is characterized by containing abrasive grains in which sulfanil groups are immobilized on the surface via covalent bonds, and a liquid medium. [Selection diagram] Fig. 4

Description

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

  Along with the high definition of semiconductor devices, the miniaturization of wiring layers formed of wirings, plugs, and the like formed in the semiconductor devices is progressing. Along with this, a technique of planarizing the wiring layer by chemical mechanical polishing (hereinafter also referred to as “CMP”) is used. In recent years, when the miniaturization is 10 nm node or more, cobalt has begun to be applied to these conductor metals, and while removing excessively laminated cobalt efficiently by CMP, corrosion of highly reactive cobalt is suppressed and good It is demanded that a smooth surface state can be formed.

  With respect to chemical mechanical polishing of such a cobalt layer and a cobalt plug (hereinafter also referred to as “cobalt film”), for example, Patent Document 1 discloses a semiconductor used in a stage preceding finish polishing corresponding to a first polishing process. As a polishing composition, a chemical mechanical polishing composition in a neutral region of pH 5 or more and 8.3 or less containing an amino acid, a nitrogen-containing heterocyclic compound, and abrasive grains is disclosed.

  Patent Document 2 discloses a group containing cobalt using a chemical mechanical polishing composition in an alkaline region having a pH of 7 or more and 12 or less, which contains a cobalt etching agent such as an oxidizing agent, a cobalt polishing rate improver, and a corrosion inhibitor. A chemical mechanical polishing method for polishing a material is disclosed. The chemical mechanical polishing composition used in this polishing method is disclosed that the corrosion potential of cobalt determined from Tafel plot is 0 mV or more and a positive potential.

  Further, Patent Document 3 discloses a chemistry for polishing a substrate containing cobalt using a chemical mechanical polishing composition in an acidic region having a pH of 4 or lower, which contains an etching agent of cobalt such as an oxidizing agent, a metal anticorrosive, and water. A mechanical polishing method is disclosed.

JP, 2006-30831, A JP, 2006-58730, A International Publication No. 2016/98817

  However, when a metal film such as cobalt is polished by chemical mechanical polishing using a conventional chemical mechanical polishing composition for acidic metal film polishing, the cobalt film is easily dissolved, and abnormal oxidation of cobalt wiring or There was a problem of causing corrosion, disconnection, and disappearance. Further, the conventional chemical mechanical polishing composition for alkaline metal polishing has a problem that it is not easy to polish efficiently because the cobalt film is chemically stable and has high hardness.

  Therefore, some aspects according to the present invention provide a chemical mechanical polishing useful for manufacturing a semiconductor device that can achieve good polishing characteristics while suppressing corrosion of a cobalt film by solving at least a part of the above problems. And a chemical mechanical polishing method using 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 the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing composition according to the present invention is:
An abrasive in which a sulfanyl group is immobilized on the surface via a covalent bond;
A liquid medium;
It is characterized by containing.

[Application Example 2]
In the chemical mechanical polishing composition of Application Example 1,
In addition, it contains potassium and sodium,
When the potassium content is M _K (ppm) and the sodium content is M _Na (ppm), M _K / M _Na = 3 × 10 ^{3 to} 3 × 10 ⁵ can be obtained.

[Application Example 3]
In the chemical mechanical polishing composition of Application Example 1 or Application Example 2,
The ratio (Rmax / Rmin) of the major axis (Rmax) and minor axis (Rmin) of the abrasive grains may be 1.0 or more and 1.5 or less.

[Application Example 4]
In the chemical mechanical polishing composition according to any one of Application Examples 1 to 3,
The pH can be 7 or more and 11 or less.

[Application Example 5]
In the chemical mechanical polishing composition of any one of Application Examples 1 to 4,
Furthermore, it contains an anionic compound having one or more double bonds,
The content of the anionic compound having one or more double bonds may be 0.001% by mass or more and 1% by mass or less.

[Application Example 6]
The chemical mechanical polishing composition according to any one of Application Example 1 to Application Example 5,
It can be used for chemical mechanical polishing of a cobalt film.

[Application Example 7]
One aspect of the chemical mechanical polishing method according to the present invention is:
It includes a step of chemical mechanical polishing a cobalt film using the chemical mechanical polishing composition of any one of Application Examples 1 to 6.

  According to the chemical mechanical polishing composition of the present invention, good polishing characteristics can be realized while suppressing the corrosion of the cobalt film in the manufacture of a semiconductor device. Therefore, the chemical mechanical polishing composition according to the present invention is particularly useful for CMP in which a cobalt film as a wiring material is to be polished.

It is explanatory drawing which shows typically the concept of the major axis and minor axis of an abrasive grain. It is explanatory drawing which shows typically the concept of the major axis and minor axis of an abrasive grain. It is explanatory drawing which shows typically the concept of the major axis and minor axis of an abrasive grain. It is sectional drawing which shows typically the to-be-processed object used for the chemical mechanical polishing method of this embodiment. It is sectional drawing for demonstrating the grinding | polishing process of the chemical mechanical grinding | polishing method of 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.

1. Chemical mechanical polishing composition The chemical mechanical polishing composition according to an embodiment of the present invention is characterized by containing abrasive grains in which sulfanyl groups are immobilized on a surface through covalent bonds, and a liquid medium. To do. Hereinafter, the chemical mechanical polishing composition according to this embodiment will be described in detail.

1.1. Abrasive Grain The chemical mechanical polishing composition according to the present embodiment contains an abrasive grain in which a sulfanyl group (-SH) is immobilized on the surface via a covalent bond. Since the abrasive grains used in the present embodiment are abrasive grains in which sulfanyl groups are fixed via covalent bonds to the surface thereof, the compound having a sulfanyl group is physically or ionically adsorbed on the surface. Abrasive grains are not included.

  The material of the abrasive grains used in the present embodiment is not particularly limited, and examples thereof include silica, ceria, alumina, zirconia, titanium oxide, and the like, but silica is preferable. Silica particles having a sulfanyl group (—SH) immobilized on the surface via a covalent bond can be produced, for example, as follows.

  First, silica particles are prepared. Examples of the silica particles include fumed silica and colloidal silica. Colloidal silica is preferable from the viewpoint of reducing polishing defects such as scratches. As colloidal silica, what was manufactured by the method described in Unexamined-Japanese-Patent No. 2003-109921 etc. can be used, for example.

  The surface modification of silica particles is described in JP2010-269985A and J.A. Ind. Eng. Chem. , Vol. 12, no. 6, (2006) 911-917 and the like can be applied. Specifically, the silica particles and the sulfanyl group-containing silane coupling agent are sufficiently stirred in an acidic medium to covalently bond the sulfanyl group-containing silane coupling agent to the surface of the silica particles. it can. Examples of the sulfanyl group-containing silane coupling agent include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

  In the silica particles thus obtained, the sulfanyl group is fixed to the surface via a covalent bond. Therefore, in the chemical mechanical polishing composition, the surface of the silica particles is negatively charged by the functional group, and the silica particles are easily adsorbed on the surface of the cobalt film. As a result, since the silica particles are localized on the surface of the cobalt film, the mechanical polishing force is increased and the polishing rate for the cobalt film is improved.

The surface potential (zeta potential) of the abrasive grains is a negative potential in the region where the pH of the chemical mechanical polishing composition is 7 or more and 11 or less, and the negative potential is preferably −20 mV or less. When the zeta potential is −20 mV or less, since the abrasive grains are easily adsorbed on the surface of the cobalt film as described above, the polishing rate for the cobalt film is improved. As the zeta potential measuring device, “ELSZ-1” manufactured by Otsuka Electronics Co., Ltd., “Zetasizer nano manufactured by Malvern Inc.
zs "and the like. The zeta potential of the abrasive can be appropriately adjusted by increasing or decreasing the amount of the sulfanyl group-containing silane coupling agent described above.

  The average particle diameter of the abrasive grains can be determined by measuring with a particle size distribution measuring apparatus based on the dynamic light scattering method. The average particle diameter of the abrasive is preferably 15 nm or more and 100 nm or less, more preferably 20 nm or more and 80 nm or less, and particularly preferably 30 nm or more and 70 nm or less. When the average particle diameter of the abrasive grains is within the above range, a practical polishing rate for the cobalt film can be achieved, and a chemical mechanical polishing composition excellent in storage stability in which precipitation and separation of the abrasive grains are difficult to occur is obtained. be able to. As a particle size distribution measuring apparatus based on the dynamic light scattering method, a nanoparticle analyzer “Delsa Nano S” manufactured by Beckman Coulter; “Zetasizer nano zs” manufactured by Malvern; “LB550” manufactured by Horiba, Ltd. Etc. In addition, 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 ratio Rmax / Rmin between the major axis (Rmax) and minor axis (Rmin) of the abrasive grains is preferably 1.0 to 1.5, more preferably 1.0 to 1.4, and particularly preferably 1.0 to 1. .3. When Rmax / Rmin is within the above range, both high polishing rate and high planarization characteristics can be achieved without causing defects in the cobalt film to be polished.

  Here, the major axis (Rmax) of the abrasive grains is the distance of the longest straight line among the straight lines connecting the end portions of the image with respect to one independent abrasive image taken by a transmission electron microscope. Shall mean. The minor axis (Rmin) of an abrasive grain means the distance of the shortest straight line among the straight lines connecting the end parts of the image with respect to one independent abrasive grain image taken by a transmission electron microscope. Shall.

  For example, when an image of one independent abrasive grain 10a photographed by a transmission electron microscope is elliptical as shown in FIG. 1, the major axis a of the elliptical shape is determined as the major axis (Rmax) of the abrasive grain. The minor axis b is determined as the minor axis (Rmin) of the abrasive grains. As shown in FIG. 2, when an image of one independent abrasive grain 10b photographed by a transmission electron microscope is an aggregate of two primary particles, the most straight line connecting the end portions of the image. The long distance c is determined as the long diameter (Rmax) of the abrasive grains, and the shortest diameter d of the straight lines connecting the end portions of the image is determined as the short diameter (Rmin) of the abrasive grains. As shown in FIG. 3, when an image of one independent abrasive grain 10 c photographed by a transmission electron microscope is an aggregate of three or more primary particles, a straight line connecting the end portions of the image. The longest distance e is determined as the major axis (Rmax) of the abrasive grains, and the shortest diameter f of the straight lines connecting the end portions of the image is determined as the minor axis (Rmin) of the abrasive grains.

  For example, by measuring the major axis (Rmax) and minor axis (Rmin) of 50 abrasive grains by the above-described determination method, and calculating the average value of the major axis (Rmax) and minor axis (Rmin), It can be obtained by calculating the ratio (Rmax / Rmin) between the average value and the average value of the minor axis.

  The content of the abrasive is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, and particularly preferably 1 to 10% by mass with respect to the total mass of the chemical mechanical polishing composition. is there. When the content ratio of the abrasive grains is within the above range, a sufficient polishing rate for the cobalt film can be obtained, and the dispersion stability of the abrasive grains in the chemical mechanical polishing composition becomes good.

1.2. Liquid Medium The chemical mechanical polishing composition according to this embodiment contains a liquid medium. Examples of the liquid medium include water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent having compatibility with water, and the like. Among these, water, a mixed medium of water and alcohol are preferably used, and water is more preferably used.

1.3. Other Components The chemical mechanical polishing composition according to the present embodiment includes, in addition to the above components, an anionic compound having one or more double bonds, potassium and sodium, an anticorrosive, JP-A No. 2014-229827, and the like. It can contain additives such as the known organic acids described (except for anionic compounds having one or more double bonds), surfactants and the like.

<Anionic compound having one or more double bonds>
The chemical mechanical polishing composition according to this embodiment preferably contains an anionic compound having one or more double bonds. Such an anionic compound can form a chelate with a cobalt atom on the modified cobalt film surface. Thereby, since cobalt elutes in the chemical mechanical polishing composition, the polishing rate of the cobalt film may be improved.

  The anionic compound having one or more double bonds is more preferably a compound represented by the following general formulas (1) to (3).

（上記一般式（１）中、Ｒ^１は炭素数１〜８のアルキル基またはカルボキシル基であり、Ｒ^２はカルボキシル基を有する炭素数１〜１５の有機基もしくはカルボキシル基を表す。）

(In the general formula (1), R ¹ represents an alkyl group having 1 to 8 carbon atoms or a carboxyl group, and R ² represents an organic group having 1 to 15 carbon atoms or a carboxyl group having a carboxyl group.)

In the general formula (2) and the general formula (3), R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent hydrogen or a C 1-3 organic group or carboxyl group having a carboxyl group. Represent. However, at least one of R ³ and R ⁴ represents an organic group having 1 to 3 carbon atoms or a carboxyl group having a carboxyl group, and at least one of R ⁵ and R ⁶ has 1 to 3 carbon atoms having a carboxyl group. Represents an organic group or a carboxyl group.

  Specific examples of the anionic compound having one or more double bonds include maleic acid, fumaric acid, quinolinic acid, quinaldic acid, oleic acid, alkenyl succinic acid, and salts thereof. The above can be used.

  The content of the anionic compound having one or more double bonds is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.00%, based on the total mass of the chemical mechanical polishing composition. 5% by mass. When the content ratio of the anionic compound having one or more double bonds is within the above range, the polishing rate for the cobalt film is improved while the corrosion of the cobalt film is suppressed.

<Potassium and sodium>
The chemical mechanical polishing composition according to this embodiment preferably contains potassium and sodium. Generally, as described in Japanese Patent Application Laid-Open No. 2000-208451 and the like, in a semiconductor manufacturing process, alkali metals such as sodium and potassium are recognized as impurities to be removed as much as possible. Therefore, in various compositions used for semiconductor processing such as a chemical mechanical polishing composition, the base for controlling pH is not an inorganic base such as sodium hydroxide, but tetramethylammonium hydroxide (TMAH) or the like. Organic bases are preferably used. However, in the present invention, by using a chemical mechanical polishing composition containing potassium and sodium in a predetermined ratio in the polishing step, the effect of improving the processing characteristics on the contrary without significantly degrading the semiconductor characteristics. Turned out to be.

Potassium and the content of sodium of the chemical mechanical polishing composition according to the present embodiment, the content of potassium M _{K (ppm),} the content of sodium is taken as _{M Na (ppm), M K} / The value of M _Na is preferably 3 × 10 ^{3 to} 3 × 10 ⁵ , and more preferably 5 × 10 ^{3 to} 5 × 10 ⁴ . When the value of M _K / M _Na is within the above range, chemical mechanical polishing can be performed without deteriorating semiconductor characteristics, and cobalt exposed on the surface to be polished in the CMP process is excessively etched and eluted. It is considered that stable processing characteristics can be maintained because this can be suppressed more effectively.

The chemical mechanical polishing composition according to this embodiment preferably contains 1 × 10 ⁻⁶ to 1 × 10 ¹ ppm of sodium, more preferably 1 × 10 ⁻³ to 1 × 10 ⁰ ppm. Moreover, the chemical mechanical polishing composition according to this embodiment preferably contains 1 × 10 ⁻² to 1 × 10 ⁶ ppm of potassium, more preferably 1 × 10 ⁻¹ to 1 × 10 ⁵ ppm. preferable.

  In order to contain potassium or sodium in the chemical mechanical polishing composition according to this embodiment, a water-soluble potassium salt or sodium salt may be added. Examples of such water-soluble salts include sodium and potassium hydroxides, carbonates, ammonium salts, and halides.

In addition, the content M _K (ppm) of potassium and the content M _Na (ppm) of sodium contained in the chemical mechanical polishing composition according to the present embodiment are determined by ICP emission analysis ( ICP-AES), ICP mass spectrometry (ICP-MS) or atomic absorption spectrophotometry (AA) can be used for determination. As the ICP emission analyzer, for example, “ICPE-9000 (manufactured by Shimadzu Corporation)” or the like can be used. As the ICP mass spectrometer, for example, “ICPM-8500 (manufactured by Shimadzu Corporation)”, “ELAN DRC PLUS (manufactured by Perkin Elmer)” or the like can be used. As the atomic absorption analyzer, for example, “AA-7000 (manufactured by Shimadzu Corporation)”, “ZA3000 (Hitachi High-Tech Science Co., Ltd.)”, and the like can be used.

In addition, the content of potassium and sodium contained in the chemical mechanical polishing composition according to the present embodiment is such that the chemical mechanical polishing composition is subjected to centrifugal separation to remove abrasive grains, and in a liquid medium other than abrasive grains. It can be calculated by quantifying the contained potassium and sodium. Therefore, it can also be confirmed that the constituent requirements of the present invention are satisfied by analyzing the chemical mechanical polishing composition by a known method.

<Anticorrosive>
The chemical mechanical polishing composition according to this embodiment may contain an anticorrosive. Examples of the anticorrosive include benzotriazole, 1,2,3-triazole, 1,2,4-triazole, and derivatives thereof. The content of the anticorrosive 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.

1.4. PH of chemical mechanical polishing composition
The pH of the chemical mechanical polishing composition according to this embodiment is preferably 7 or more and 11 or less, more preferably 8 or more and 11 or less, and particularly preferably 9 or more and 11 or less. When the pH is within the above range, the cobalt film can be polished while suppressing the corrosion of the cobalt film, so that good polishing characteristics can be obtained. On the other hand, when the pH is less than 7, the polishing rate of the cobalt film is improved, but corrosion of the cobalt film is likely to occur, so that it is difficult to obtain good polishing characteristics.

  Examples of means for adjusting the pH of the chemical mechanical polishing composition include a method of adding a base to the chemical mechanical polishing composition. Examples of the base that can be added include ammonia, potassium hydroxide, sodium hydroxide, TMAH (tetramethylammonium hydroxide), and the like. These bases can be used singly or in combination of two or more.

1.5. Cobalt natural potential of chemical mechanical polishing composition The cobalt natural potential of the chemical mechanical polishing composition according to this embodiment is preferably 0 to -500 mV, more preferably -200 to -500 mV. . When the natural potential of cobalt in the chemical mechanical polishing composition is within the above range, it is considered that the cobalt exposed on the surface to be polished can be prevented from being excessively etched and eluted in the polishing step. On the other hand, when the natural potential of cobalt in the chemical mechanical polishing composition contained in the chemical mechanical polishing composition exceeds the above range, cobalt is likely to be oxidized, and chemically stable cobalt oxide or hydroxide Cobalt is likely to be generated, and it is difficult to perform efficient polishing, which is not preferable. On the other hand, when the natural potential of cobalt in the chemical mechanical polishing composition contained in the chemical mechanical polishing composition is less than the above range, excessive etching of cobalt proceeds and the flatness and electrical characteristics of the polished surface are increased. It may deteriorate.

  In the present invention, the natural potential (rest potential) of cobalt of the chemical mechanical polishing composition can be determined by quantifying the open circuit potential (OCP) of the chemical mechanical polishing composition. The natural potential is synonymous with the corrosion potential, and the corrosion potential can also be obtained by quantifying the corrosion potential from the Tafel plot by linear sweep voltammetry (LSV). As the OCP and LSV apparatus, for example, “electrochemical measurement apparatus HZ-7000 (manufactured by Hokuto Denko Co., Ltd.)” or the like can be used.

1.6. Surface tension of chemical mechanical polishing aqueous dispersion The surface tension of the chemical mechanical polishing composition according to this embodiment is preferably 20 to 75 mN / m, and more preferably 50 to 75 mN / m. When the surface tension of the chemical mechanical polishing composition is within the above range, it is considered that defects on the cobalt surface can be reduced in the polishing step.

  The surface tension of the chemical mechanical polishing composition can be adjusted by increasing or decreasing the amount of the anionic compound having one or more of the above-described double bonds and other additives.

  The surface tension of the chemical mechanical polishing composition can be determined by quantifying the chemical mechanical polishing composition using the hanging drop method (pendant drop method). As the surface tension meter, for example, “contact angle meter DMs-401 (manufactured by Kyowa Interface Science Co., Ltd.)” or the like can be used.

1.7. Applications The chemical mechanical polishing composition according to the present embodiment can achieve a practical polishing rate for a cobalt film as described above, and has a corrosion inhibiting effect on the cobalt film. Therefore, the chemical mechanical polishing composition according to this embodiment is suitable as a polishing material for chemical mechanical polishing of a cobalt film that forms a metal wiring, a metal gate, a metal plug, and the like in a manufacturing process of a semiconductor device.

1.8. Method for Preparing Chemical Mechanical Polishing Composition The chemical mechanical polishing composition according to this embodiment can be prepared by dissolving or dispersing the above-described components in a liquid medium such as 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.

  Moreover, the chemical mechanical polishing composition according to the present embodiment can be prepared as a concentrated stock solution and diluted with a liquid medium such as water when used.

2. Chemical Mechanical Polishing Method A chemical mechanical polishing method according to an embodiment of the present invention includes a step of chemical mechanical polishing a cobalt film using the chemical mechanical polishing composition described above. 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. Production of Device (Subject to be Processed) FIG. 4 shows an object to be processed 100 used in the chemical mechanical polishing method according to this embodiment.
(1) First, an insulating film 20 is formed on a silicon substrate (not shown) by a plasma CVD method or a thermal oxidation method. Examples of the insulating film 20 include a TEOS film.
(2) A protective film 30 is formed on the insulating film 20 by using a CVD method or a thermal oxidation method. Examples of the protective film 30 include a SiN film.
(3) The wiring recess 40 is formed by etching the insulating film 20 and the protective film 30 so as to communicate with each other.
(4) The barrier metal film 50 is formed so as to cover the surface of the protective film 30 and the bottom and inner wall surface of the wiring recess 40 using the CVD method or the PVD method. The barrier metal film 50 is preferably Ti or TiN from the viewpoint of excellent adhesion to the cobalt film and diffusion barrier properties with respect to the insulating film and the protective film, but is not limited to this, and Ta, TaN, Mn, Ru, etc. There may be.
(5) The object 100 is obtained by depositing cobalt on the barrier metal film 50 by PVD, CVD, or plating to form the cobalt film 60.

2.2. Chemical Mechanical Polishing Method Next, the object 100 is subjected to two-stage polishing. As a first polishing process, in order to remove the cobalt film 60 deposited on the barrier metal film 50 of the object 100, a high polishing rate is applied to cobalt described in JP-A-2006-30831. Chemical mechanical polishing is performed using the chemical mechanical polishing composition shown. By this chemical mechanical polishing, the cobalt film 60 is continuously polished until the protective film 30 or the barrier metal film 50 is exposed. Usually, it is necessary to stop polishing after confirming that the protective film 30 or the barrier metal film 50 is exposed. When using a chemical mechanical polishing composition that has a very high polishing rate for the cobalt film but hardly polishes the barrier metal film, the chemical mechanical polishing is performed when the barrier metal film 50 is exposed as shown in FIG. Therefore, chemical mechanical polishing can be self-stopped (self-stop).

  Next, as the second polishing treatment step, the surface to be treated in which the cobalt film 60, the barrier metal film 50, and the protective film 30 or the insulating film 20 coexist using the chemical mechanical polishing composition of the present invention described above. By polishing the surface, it is possible to polish without reducing the polishing rate while reducing the corrosion of the cobalt film surface.

2.3. Chemical mechanical polishing apparatus In the chemical mechanical polishing method according to the present embodiment, a commercially available chemical mechanical polishing apparatus can be used. As a commercially available chemical mechanical polishing apparatus, for example, “EPO-112” and “EPO-222” manufactured by Ebara Manufacturing Co., Ltd .; “LGP-510” and “LGP-552” manufactured by Lapmaster SFT, Applied Materials Manufactured, model “Mirra”, “Reflexion”; manufactured by G & P TECHNOLOGY, model “POLI-400L”, and the like.

Preferred polishing conditions should be set as appropriate depending on the chemical mechanical polishing apparatus used. For example, when the above-mentioned “EPO-112” is used as the chemical mechanical polishing apparatus, the following conditions can be used.
-Surface plate rotation speed: preferably 30-120 rpm, more preferably 40-100 rpm
Head rotation speed: preferably 30 to 120 rpm, more preferably 40 to 100 rpm
Platen rotational speed / head rotational speed ratio; preferably 0.5 to 2, more preferably 0.7 to 1.5 Polishing pressure: preferably 60~200gf / cm ^2, more preferably 100～150Gf / cm ²
-Chemical mechanical polishing composition supply rate; preferably 50 to 300 mL / min, more preferably 100 to 200 mL / min

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

3.1. Preparation of aqueous dispersion containing sulfanyl group-modified colloidal silica <Silica particle dispersion A>
The silica particle dispersion A was produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20 mass%, average particle diameter 75 nm) manufactured by Fuso Chemical Industry Co., Ltd. and 6 g of 3-mercaptopropyltrimethoxysilane were mixed. Heated to reflux for 2 hours. Thus, a sulfinylated silica particle dispersion A having a silica concentration of 20% by mass and a mean particle size of 72 nm was obtained.

  Silica particle dispersion A was diluted to 0.01% with ion-exchanged water, placed on a collodion membrane having Cu grit having a mesh size of 150 μm, and dried at room temperature. In this way, after preparing a sample for observation so as not to break the particle shape on the Cu grit, using a transmission electron microscope (“H-7650” manufactured by Hitachi High-Technologies Corporation), the photographing magnification is 20000 times. An image of the particles was taken, the major axis and minor axis of 50 silica particles were measured, and the average value was calculated. The ratio (Rmax / Rmin) calculated from the average value (Rmax) of the major axis and the average value (Rmin) of the minor axis was 1.2.

<Silica particle dispersion B>
The silica particle dispersion B was produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3L; silica content (solid content concentration) 20 mass%, average particle diameter 63 nm) manufactured by Fuso Chemical Co., Ltd. and 6 g of 3-mercaptopropyltrimethoxysilane were mixed, Heated to reflux for 2 hours. In this way, a sulfinylated silica particle dispersion B having a silica concentration of 20% by mass and an average secondary particle size of 62 nm was obtained. When the ratio (Rmax / Rmin) was calculated from the average value of the major axis (Rmax) and the average value of the minor axis (Rmin), it was 1.1.

<Silica particle dispersion C>
The silica particle dispersion C was produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20 mass%, average particle diameter 75 nm) manufactured by Fuso Chemical Industry Co., Ltd. and 6 g of 3-aminopropyltrimethoxysilane were mixed, Heated to reflux for 2 hours. Thus, an aminated silica particle dispersion C having a silica concentration of 20% by mass and an average particle size of 73 nm was obtained. The ratio (Rmax / Rmin) calculated from the average value (Rmax) of the major axis and the average value (Rmin) of the minor axis was 1.2.

<Silica particle dispersion D>
The silica particle dispersion D was produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20 mass%, average particle diameter 75 nm) manufactured by Fuso Chemical Co., Ltd. and 6 g of 2-nitrobenzyl ester are mixed for 2 hours. Heated to reflux. Thereafter, light irradiation was performed for 3 hours to obtain a carboxylated silica particle dispersion D having a silica concentration of 20% by mass and a mean particle diameter of 75 nm. The ratio (Rmax / Rmin) calculated from the average value (Rmax) of the major axis and the average value (Rmin) of the minor axis was 1.2.

<Silica particle dispersion E>
The silica particle dispersion E was produced as follows. First, 5 kg of high-purity colloidal silica (product number: PL-3; silica content (solid content concentration) 20 mass%, average particle diameter 75 nm) manufactured by Fuso Chemical Co., Ltd. and 6 g of 3-mercaptopropyltrimethoxysilane were mixed, After heating to reflux for 2 hours, a thiolated silica sol is obtained. The silica sol was added with an oxidizing agent such as hydrogen peroxide and heated to reflux for 8 hours to oxidize the surface and fix sulfonic acid on the surface. Thus, a silica particle dispersion E having a silica concentration of 20% by mass and an average particle size of 73 nm was obtained. The ratio (Rmax / Rmin) calculated from the average value (Rmax) of the major axis and the average value (Rmin) of the minor axis was 1.2.

3.2. Preparation of chemical mechanical polishing composition In a polyethylene container, each component is added so as to have the content ratio shown in Table 1 or Table 2, and potassium hydroxide, sodium hydroxide, and hydrogen peroxide water are added as necessary. In addition, the chemical mechanical polishing composition of each example and each comparative example was prepared by adjusting the pH, natural potential, potassium content, and sodium content shown in Table 1 or Table 2.

3.3. Evaluation method 3.3.1. Polishing Rate Evaluation Using the chemical mechanical polishing composition prepared above, a chemical mechanical polishing test was conducted for 1 minute under the following polishing conditions using a wafer with a cobalt film of 200 nm having a diameter of 12 inches as an object to be polished.

<Polishing conditions>
・ Polisher: G & P TECHNOLOGY, model “POLI-400L”
・ Polishing pad: Fuji Spinning Co., Ltd., “Multi-rigid polyurethane pad; H800-type1 (
3-1S) 775 "
・ Chemical mechanical polishing composition supply rate: 100 mL / min ・ Surface plate rotation speed: 100 rpm
-Head rotation speed: 90 rpm
-Head pressing pressure: 2 psi
Polishing rate (Å / min) = (film thickness before polishing−film thickness after polishing) / polishing time The thickness of the cobalt film is determined by a resistivity measuring machine (manufactured by NPS, model “Σ −5 ”), the resistance was measured by a direct current four-probe method, and the sheet resistance value and the volume resistivity of cobalt were calculated by the following formula.
Film thickness (Å) = [Volume resistivity of cobalt film (Ω · m) ÷ Sheet resistance (Ω))] × 10 ¹⁰

The evaluation criteria for the polishing rate evaluation are as follows. The results are also shown in Table 1 or Table 2.
-When the polishing rate is 400 Å / min or more, the polishing rate is high, so in actual semiconductor polishing, it is possible to easily ensure a speed balance with polishing of other material films, and it is extremely practical because it is very practical. ◎ ”.
-When the polishing rate is 200 Å / min or more and less than 400 Å / min, since the polishing rate is high, it is possible to secure a balance with the polishing of other material films in actual semiconductor polishing, and it is determined to be good because it is practical. ".
When the polishing rate was less than 200 Å / min, the polishing rate was low, so that it was difficult to put into practical use and was judged to be defective, and indicated as “x”.

3.3.2. Corrosion Evaluation A wafer with a cobalt film having a diameter of 12 inches polished by the above polishing rate evaluation was cut to prepare a 2 × 2 cm test piece, and a dimensional fast scan was used with a scanning atomic force microscope (manufactured by Bluker Corporation, AFM). 12 points were observed at a frame size of 10 μm, and the average value of the arithmetic average roughness at 12 points was calculated. The evaluation criteria are as follows. The results are also shown in Table 1 or Table 2.
-When the average value of arithmetic average roughness was less than 0.6 nm, cobalt corrosion was suppressed and it judged that it was very favorable and described as "(circle)".
-When the average value of arithmetic average roughness was 0.6 nm or more, since cobalt corrosion was not able to be suppressed and it was difficult to use, it judged that it was inferior and was described as "x".

In Table 1 and Table 2, the total amount of each component in each Example and each Comparative Example is 100 parts by mass, and the balance is ion-exchanged water. Further, the following components in Table 1 and Table 2 will be supplemented.
<Abrasive>
PL-3: manufactured by Fuso Chemical Industry Co., Ltd., trade name “PL-3”, Rmax / Rmin = 1.2
PL-3L: manufactured by Fuso Chemical Industry Co., Ltd., trade name “PL-3L”, Rmax / Rmin = 1.2

3.4. Evaluation Results According to the chemical mechanical polishing composition of the present invention of Examples 1 to 9, while the cobalt film can be polished at a high polishing rate, the roughness of the cobalt film after polishing is low, low corrosion, and storage. The stability results were also good. On the other hand, in the chemical mechanical polishing compositions of Comparative Examples 1 to 5, it was impossible to achieve both the corrosion inhibition of the cobalt film and the high polishing rate of the cobalt film, and good polishing characteristics could not be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10a, 10b, 10c ... abrasive grains, 20 ... insulating film, 30 ... protective film, 40 ... recess for wiring, 50 ... barrier metal film, 60 ... cobalt film, 100 ... object to be processed

Claims (7)

An abrasive in which a sulfanyl group is immobilized on the surface via a covalent bond;
A liquid medium;
A chemical mechanical polishing composition comprising: In addition, it contains potassium and sodium,
The content of the potassium _M K (ppm), the content of the sodium is taken _{as M Na (ppm), M K} / M Na = a ^{3 × 10 3 ~3 × 10 5} , in claim 1 The composition for chemical mechanical polishing as described.   The chemical mechanical polishing composition according to claim 1 or 2, wherein a ratio (Rmax / Rmin) of a major axis (Rmax) and a minor axis (Rmin) of the abrasive grains is 1.0 or more and 1.5 or less. .   The chemical mechanical polishing composition according to any one of claims 1 to 3, wherein the pH is 7 or more and 11 or less. Furthermore, it contains an anionic compound having one or more double bonds,
The chemical mechanical polishing composition according to any one of claims 1 to 4, wherein the content of the anionic compound having one or more double bonds is 0.001% by mass or more and 1% by mass or less. .   The chemical mechanical polishing composition according to any one of claims 1 to 5, which is used for chemical mechanical polishing of a cobalt film.   A chemical mechanical polishing method comprising a step of chemical mechanical polishing a cobalt film using the chemical mechanical polishing composition according to any one of claims 1 to 6.

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