JP2003017448A - Metal abrasives, metal abrasive composition and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide metal abrasives, capable of suppressing occurrence of damages on a polishing surface and suppressing dishing, by rapidly polishing the metal and to provide a metal abrasive composition, and to provide a method for polishing using them. SOLUTION: The metal abrasives comprises chelate resin particles, containing an aminocarboxylic acid or an iminodiacetic acid as functional groups, in such a manner that paired ions of the functional group are at least one type selected from among a group consisting of hydrogen ion and ammonium ion, represented by the formula<+> NR1 R2 R3 R4 , (wherein R1 , R2 , R3 and R4 are each independently a hydrogen atom, 1-5C saturated alkyl group or benzyl group).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a metal abrasive, a metal polishing composition, and a polishing method using them. More specifically, a metal film used for manufacturing a semiconductor device,
In particular, it relates to a metal abrasive for polishing a copper-based metal film, a metal polishing composition, and a polishing method using the polishing composition.

[0002]

2. Description of the Related Art In recent years, various fine processing techniques have been researched and developed for higher integration and higher performance of LSI. Among them, a chemical mechanical polishing method (chemical mechanical polishing, sometimes abbreviated as CMP hereinafter) has been attracting attention. CMP is a technique that combines a chemical action and a mechanical action between a polishing composition and an object to be polished, and particularly flattening of an interlayer insulating film, formation of a metal plug, formation of a buried metal wiring in a multilayer wiring forming process. It has become an indispensable technology in such cases.

From the viewpoint of increasing the speed of LSIs, the formation of embedded wiring using a metal having a low resistance has been actively studied, and accordingly, various studies have been conducted on a metal abrasive having a low resistance. Has been.

For example, in order to improve the polishing rate, the metal abrasive contains an etching additive such as a complexing agent (eg, amine or glycine) which reacts with copper ions to form a water-soluble copper complex. By doing so, a method of polishing at a high speed while performing etching is known. However, when polishing the metal wiring formed on the semiconductor substrate,
In the polishing composition containing an etching additive, the metal is isotropically etched, and the thickness of the central portion of the metal wiring film embedded in the groove or opening becomes thin (D
There is a problem that the resistance value becomes high as well as the flatness is impaired due to the occurrence of ashing).

Further, a method of using abrasive particles containing a soft organic polymer compound as a main component for polishing a copper-based metal having a low hardness has been proposed. However, if an etching additive is not included. There was a problem that a high polishing rate could not be obtained, and when an etching additive was added, dishing occurred as in the above case.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to polish a metal at a high speed, suppress the generation of scratches on the polished surface, and suppress dishing, a metal polishing composition, and a metal polishing composition therefor. It is to provide a polishing method to be used.

[0007]

Means for Solving the Problems As a result of intensive studies to find a metal abrasive free from the above problems, the present inventors have found that a metal composed of chelate resin particles having a specific functional group and a counter ion. The inventors have found that an abrasive can polish metal at high speed, suppress the generation of scratches on the polished surface, and suppress dishing, and have completed the present invention.

That is, the present invention is [1] a metal abrasive comprising chelate resin particles having aminocarboxylic acid or iminodiacetic acid as a functional group, the counterion of the functional group being hydrogen ion and the following general formula: The present invention relates to a metal abrasive, which is at least one selected from the group consisting of the ammonium ions represented. ⁺ NR ₁ R ₂ R ₃ R ₄ (in the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a benzyl group)

The present invention also relates to [2] a metal polishing composition containing the metal polishing material according to the above [1]. Furthermore, the present invention relates to [3] the metal polishing composition according to the above [2], which further contains at least one selected from the group consisting of spherical particles, benzotriazole and benzotriazole derivatives. Furthermore, the present invention provides [4]
The present invention relates to a metal polishing method, which comprises polishing by chemical mechanical polishing using the metal polishing composition as described in [2] above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The metal abrasive of the present invention is a metal abrasive containing chelate resin particles having aminocarboxylic acid or iminodiacetic acid as a functional group.

The chelate resin has a multidentate ligand having a plurality of coordination atoms forming a complex with a metal on the surface. Generally, when a polydentate ligand having two or more coordinating atoms binds to a metal ion, it forms a chelate ring and has stability higher than that of a complex in which a monodentate ligand is coordinated. Therefore, the ability to capture the metal ions to be polished increases, and the chemical action can be increased.

The chelate resin particles used in the present invention must have aminocarboxylic acid or iminodiacetic acid as a functional group from the viewpoint of polishing characteristics.

As the chelate resin particles having these functional groups, Na type in which the counter ion of the functional group is sodium ion is generally used, but when applied to the semiconductor manufacturing process, sodium ion diffuses into the insulating film. Therefore, in the present invention, a hydrogen ion (H type) or an ammonium ion (ammonium type) represented by the following general formula, which has little influence on a semiconductor device, is used as a counter ion in the present invention. It is necessary to be. ⁺ NR ₁ R ₂ R ₃ R ₄ (In the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a benzyl group.) R ₁ , R ₂ , R ₃ and R ₄ are preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of the saturated alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s
Examples thereof include an ec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a tert-pentyl group.

The chelate resin particles having aminocarboxylic acid or iminodiacetic acid as a functional group can be produced by a known method. For example, a method of polymerizing a monomer having a desired functional group, a method of chemically converting the functional group of the polymerized polymer particles into a desired functional group, and the like can be mentioned.

A known method can also be applied to the method in which the counter ion of the functional group is at least one selected from the group consisting of H type and ammonium type represented by the above general formula.
For example, a method of making a target counterion from the raw material stage, a method of making another counterion a target counterion by an ion exchange method, and the like can be mentioned. In the ion exchange method, for example, the chelate resin particles produced with Na as the counter ion are packed in a column, and an aqueous hydrochloric acid solution is passed through to form an H type, and an aqueous amine solution is passed through the column. Can be ammonium type. In the ion exchange method,
In addition to the method of using a column for distribution, it is also possible to perform batch processing by stirring or the like.

The above-mentioned chelate resin particles are preferably chelate resin particles having an average particle size of 1.0 μm or less. The use of chelate resin particles having an average particle size of 1.0 μm or less further improves the processing accuracy of the polished surface. Here, the average particle diameter means an average particle diameter (average secondary particle diameter) measured by a dynamic light scattering method.

The chelate resin particles having an average particle size of 1.0 μm or less can be obtained by a method of wet pulverizing a chelate resin having aminocarboxylic acid or iminodiacetic acid as a functional group.

Examples of the wet crushing method include a method using a known crushing device such as a vibration mill and a ball mill. It is preferable to use zirconia or a polymer in the liquid contact part in order to avoid metal contamination from the pulverizer or the like.
If necessary, coarse particles may be classified by operations such as wet gravity sedimentation, centrifugal sedimentation, and filtering, and the particles may be sized to a desired particle size before use.

Further, it is suitable to perform the coarse crushing treatment by the dry crushing before the wet crushing in order to improve the crushing efficiency in the wet crushing. As a method for dry pulverization, for example, a known pulverizer such as a jaw crusher, a gyratory crusher, a roll crusher, an edge runner, a hammer crusher, a ball mill, a jott mill, a disc crusher, or the like can be used. It is preferable to use zirconia or a polymer in the contact portion in order to avoid metal contamination from a pulverizer or the like. If necessary, coarse particles may be classified by an apparatus such as dry air classification, and the particles may be sized to a desired particle size before use.

The counter ion of the functional group of the chelate resin to be wet-milled is preferably at least one selected from the group consisting of H type and ammonium type represented by the above general formula, but the counter ion is H When the type is not ammonium type, the counter ions may be H type or ammonium type by ion exchange after wet pulverization. For example, N
After wet-milling the a-type chelate resin, a protonic acid such as hydrochloric acid or nitric acid is added to liberate sodium ions, and the sodium ions are removed by membrane filtration or the like to obtain H-type. Further, an ammonium type can be obtained by adding an amine to the H type.

When the metal abrasive of the present invention is used for polishing a metal, it is preferable to prepare a slurry metal polishing composition in which the abrasive and an oxidizing agent are dispersed in water. The oxidizing agent used is preferably an oxidizing agent having an effect of improving the polishing rate. As the oxidizing agent, known oxidizing agents such as hydrogen peroxide, iodic acid and iodate can be used, and among these, hydrogen peroxide is preferably used.

The concentration of the oxidizing agent in the polishing composition is usually
It is preferably about 0.1 to 15% by weight with respect to the metal polishing composition. If the concentration of the oxidant is less than 0.1% by weight, the effect of improving the polishing rate tends to be difficult to appear, and even if it exceeds 15% by weight, the improvement of the polishing rate commensurate with the concentration is recognized. Tend not to. Further, the timing of addition of the oxidizing agent is not particularly limited as long as there is no deterioration of the oxidizing agent and the like.
It is preferable to add it just before polishing.

As the method for preparing the polishing composition, the abrasive, the oxidizing agent and water may be mixed and dispersed at the same time, or the abrasive and the water are mixed in advance and then the oxidizing agent is mixed. The oxidizing agent may be mixed in advance and then water may be mixed, or the oxidizing agent and water may be mixed in advance, and then the abrasive may be mixed. As a dispersion method for forming a slurry, a known method can be applied,
For example, a dispersion method using a homogenizer, ultrasonic waves, a wet medium mill and the like can be mentioned. The slurry concentration (abrasive content in the polishing composition) is usually about 1 to 30% by weight. If the concentration of the abrasive is less than 1% by weight, the effect of improving the polishing rate tends to be difficult to appear, and even if it exceeds 30% by weight, the improvement of the polishing rate commensurate with the concentration tends not to be observed. There is.

The metal polishing composition of the present invention further contains at least one selected from the group consisting of spherical particles, benzotriazole and benzotriazole derivatives for the purpose of improving the flattening property during polishing of a metal having irregularities on the surface. One kind can be added. The spherical particles are not particularly limited as long as they are substantially spherical, but for example, inorganic oxide particles such as colloidal silica and colloidal alumina, and polymer particles such as emulsion produced by emulsion polymerization can be used. The concentration of spherical particles is about 0.1 to 3 of the total amount.
It is preferably 0% by weight. The concentration of benzotriazole and benzotriazole derivative is about 0.0% of the total amount.
It is preferably from 1 to 0.2% by weight.

If desired, the metal polishing composition of the present invention may contain additives such as surfactants for the purpose of stabilizing dispersion, preventing sedimentation, and improving the surface roughness of the polishing surface. Anionic, cationic, nonionic and amphoteric surfactants can be used, and two or more types can be used in combination.

The pH of the metal polishing composition of the present invention is not unique because the pH value effective for polishing varies depending on the type of functional group and the type of target metal, but is usually about 1 to 8, and preferably 2 to 6. If the pH of the polishing composition is less than 1, problems in handling the polishing composition and corrosion of the polishing apparatus tend to occur. The pH of the metal polishing composition of the present invention can be adjusted using a known acid or alkali.
To adjust pH, nitric acid, phosphoric acid,
It is preferable to use an acid or alkali such as sulfuric acid, ammonium hydroxide or amine.

The metal polishing composition of the present invention can be used for polishing various metals, preferably copper-based metals. The polishing composition is suitably used for polishing a metal film, particularly a copper-based metal film formed on a semiconductor substrate. Here, examples of the copper-based metal include a pure copper film and a copper alloy film.

By using the metal polishing composition of the present invention, it is possible to polish a metal at a high speed and suppress the generation of scratches on the polished surface.

By using the metal polishing composition of the present invention, it is possible to polish a metal by chemical mechanical polishing. Therefore, the polishing method of the present invention can be applied to a metal film, particularly a metal formed on a semiconductor substrate. It can be preferably applied to a film, especially a copper film.

[0030]

EXAMPLES The present invention will be described below with reference to examples.
It goes without saying that the present invention is not limited to the examples.

As for the average particle size of the particles, a cumulative 50% size was measured with a Microtrac UPA particle size distribution meter (manufactured by Nikkiso Co., Ltd.) and this was taken as the average particle size. The polishing rate was measured by polishing a wafer with a copper film formed by sputtering under the following conditions. [Polishing conditions] Polishing machine: MECAPOL E-460 (PRESI) Pad: Polyurethane type Rotation speed of rotating platen: 60 rpm Rotation speed of wafer holder: 60 rpm Polishing pressure: 200 g / cm ² Polishing composition flow rate: 100 ml / min Polishing time: 1 minute

Example 1 Chelating resin having an iminodiacetic acid group as a functional group (trade name: Sumichelate MC-700, manufactured by Sumitomo Chemical Co., Ltd.,
1 L of counter ion: Na type) was packed in the column, washed with ultrapure water, 10 L of a 2N hydrochloric acid aqueous solution was passed, and washed with ultrapure water again to obtain an H type (H ⁺ ) chelate resin.
Further, 10 L of 2N aqueous ammonia was passed through the column and the column was washed again with ultrapure water to obtain an ammonium type (NH ₄ ) chelate resin. The above ammonium-type chelate resin was dry-ground (using Micro Powder made by West Co., Ltd.), and 140 g of ultrapure water was added to 120 g of the obtained ground product, which was 5 mm.
Ball mill treatment was performed using φ zirconia balls under the conditions of a rotation speed of 130 rpm and a treatment time of 40 hours. The average particle size of the chelate resin particles in the obtained slurry is 0.6.
It was 5 μm. Hydrogen peroxide and benzotriazole were added to the obtained slurry to adjust the chelate resin concentration to 10% by weight, the hydrogen peroxide concentration to 1.5% by weight, and the benzotriazole concentration to 0.01% by weight, and then nitric acid was used to adjust the pH.
A polishing composition was obtained as No. 4. The polishing results are shown in Table 1.

Example 2 Chelating resin having an iminodiacetic acid group as a functional group (trade name: Sumichelate MC-700, manufactured by Sumitomo Chemical Co., Ltd.,
1 L of counter ion: Na type) was packed in the column, washed with ultrapure water, 10 L of a 2N hydrochloric acid aqueous solution was passed, and washed again with ultrapure water to obtain an H type chelate resin. This chelate resin was added to 500 g of a 4% tetramethylammonium hydroxide aqueous solution and stirred to obtain a tetramethylammonium type (N (CH ₄ )) chelate resin. The mixture of the tetramethylammonium chelate resin and an aqueous solution of tetramethylammonium hydroxide was subjected to ball mill treatment using 5 mmφ zirconia balls under the conditions of a rotation speed of 70 rpm and a treatment time of 29 hours. The average particle size of the chelate resin particles in the obtained slurry was 0.37 μm. Hydrogen peroxide and benzotriazole were added to the obtained slurry to obtain a chelate resin concentration of 10% by weight, a hydrogen peroxide concentration of 1.5% by weight, and a benzotriazole concentration of 0.0%.
After adjusting to 1% by weight, pH was adjusted to 4 with nitric acid to obtain a polishing composition. The polishing results are shown in Table 1.

COMPARATIVE EXAMPLE 1 Inorganic oxide particles, colloidal silica (trade name: Snowtex, manufactured by Nissan Chemical Industries, Ltd., average particle size: 0.1 μm) were used as polishing abrasive particles, and the abrasive particle concentration was 10% by weight and peroxide was used. Hydrogen concentration 1.5% by weight, benzotriazole concentration 0.01
After adjusting to the weight%, the pH was adjusted to 4 with nitric acid to obtain a polishing composition. The polishing results are shown in Table 1.

Comparative Example 2 Polymethylmethacrylate (PMMA) was used as polishing abrasive grains.
Using aqueous emulsion resin particles (average particle size 0.20 μm), the abrasive grain concentration was adjusted to 10% by weight, the hydrogen peroxide concentration was 1.5% by weight, and the benzotriazole concentration was 0.01% by weight. The pH was adjusted to 4 to obtain a polishing composition. The polishing results are shown in Table 1.

[0036]

[Table 1]

In the case of Example 1 or Example 2 which is a metal polishing composition comprising chelate resin particles, a high polishing rate was achieved, but colloidal silica of Comparative Example 1 and PMMA aqueous emulsion resin particles of Comparative Example 2 were obtained. With the polishing composition consisting of, the polishing rate was low.

[0038]

According to the present invention, metal is polished at high speed,
Generation of scratches on the polished surface can be suppressed and dishing can be suppressed, and a particularly excellent processed surface can be obtained.

Claims (10)

[Claims] 1. A metal abrasive comprising chelate resin particles having aminocarboxylic acid or iminodiacetic acid as a functional group, the counterion of the functional group being hydrogen ion and ammonium ion represented by the following general formula. A metal abrasive, which is at least one selected from the group. ⁺ NR ₁ R ₂ R ₃ R ₄ (in the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a benzyl group) 2. The metal abrasive according to claim 1, wherein the functional group of the chelate resin particles is iminodiacetic acid. 3. The metal abrasive according to claim ₁ , wherein R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms. 4. The chelate resin particles have an average particle size of 1.0 μm.
The metal abrasive according to any one of claims 1 to 3, which is m or less. 5. The metal abrasive according to claim 1, wherein the metal is a copper-based metal. 6. A metal polishing composition comprising the metal polishing material according to claim 1. 7. The metal polishing composition according to claim 6, further comprising an oxidizing agent. 8. The metal polishing composition according to claim 7, wherein the oxidizing agent is hydrogen peroxide. 9. The metal polishing composition according to claim 6, further comprising at least one selected from the group consisting of spherical particles, benzotriazole, and benzotriazole derivatives. 10. A method for polishing a metal, which comprises polishing the metal polishing composition according to claim 6 by chemical mechanical polishing.