JP6015931B2 - Chemical mechanical polishing aqueous dispersion and chemical mechanical polishing method - Google Patents

Description

  The present invention relates to an aqueous dispersion for chemical mechanical polishing and a chemical mechanical polishing method.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of LSIs. Chemical mechanical polishing (hereinafter also referred to as “CMP”) is one of them, and is frequently used in LSI manufacturing processes, particularly in the formation of interlayer insulating films, metal plugs, and embedded wiring (damascene wiring) in the multilayer wiring forming process. It is a technology that is being used. This damascene wiring technology can simplify the wiring process, improve yield and reliability, and its application is expected to expand in the future. Currently, copper is mainly used as a wiring metal for damascene wiring because of low resistance in high-speed logic devices. Further, in a memory device typified by a DRAM, aluminum or tungsten is used as a wiring metal for the purpose of cost reduction. Considering both low resistance and cost reduction, aluminum and alloys thereof having the second lowest resistance after copper are considered promising as damascene wiring metals in any device.

  A polishing composition for polishing an aluminum film and an alloy film thereof (hereinafter also simply referred to as “aluminum film”) is required to have various performances such as an appropriate polishing rate and scratch resistance. Furthermore, micro pitting corrosion occurring on the surface of the aluminum film with the further miniaturization of wiring in recent years has become a big problem. This pitting corrosion refers to a corrosion form in which corrosion holes are concentrated only in a specific place, and most of the others remain passive. The reason why this pitting corrosion occurs is considered to be because non-uniform portions such as crystal grain boundaries on the surface of the aluminum film are partially corroded (see, for example, Non-Patent Document 1). It is known that it occurs remarkably in the acidic region.

  As a polishing composition for suppressing such pitting corrosion, for example, a polishing composition to which a compound having an azole structure is added has been proposed (see, for example, Patent Document 1). As a means for suppressing pitting corrosion on the surface of the aluminum film, a method of adding an anticorrosive agent has been proposed (see, for example, Patent Documents 2 to 3).

Japanese Patent No. 4263397 Japanese Patent Publication No. 6-80192 Japanese Patent Laid-Open No. 10-168585

Shigeru Kijima, “Anti-corrosion Engineering”, Nikkan Kogyo Shimbun, 1982

  However, the polishing composition described in Patent Document 1 mainly has a copper film as an object to be polished, and the effect of suppressing corrosion generated in the aluminum film is not sufficient. Moreover, since the general anticorrosive agent for aluminum of patent documents 2-3 forms the strong protective film for corrosion suppression, it forms both formation of a protective film, and removal of a protective film and a grinding | polishing target object. It was not easy to apply to a chemical mechanical polishing aqueous dispersion for manufacturing semiconductor devices. Therefore, there has been a demand for the development of a new chemical mechanical polishing aqueous dispersion that can achieve both a sufficient polishing rate for aluminum films required for next-generation LSIs and suppression of pitting corrosion.

  Therefore, some aspects of the present invention solve the above-described problems, and in the semiconductor device manufacturing process, can achieve both a high polishing rate and suppression of pitting corrosion for the aluminum film and its alloy film, and are favorable. An aqueous dispersion for chemical mechanical polishing having storage stability and a chemical mechanical polishing method using the same are 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.

[Application Example 1]
One aspect of the chemical mechanical polishing aqueous dispersion according to the present invention is:
(A) 0.1 to 10% by weight of abrasive grains,
(B) 0.01 to 2% by mass of a phosphoric acid ester compound having an organic group having 1 to 5 carbon atoms;
And pH is 1 or more and 4 or less.

[Application Example 2]
In the chemical mechanical polishing aqueous dispersion of Application Example 1,
The (B) phosphate ester compound may contain at least one selected from a phosphate monoester and a phosphate diester.

[Application Example 3]
In the chemical mechanical polishing aqueous dispersion of Application Example 1 or Application Example 2,
The (B) phosphate ester compound may be a compound represented by the following general formula (1).
(R ¹ O) (R ² O) —PO (OH) (1)
In (the above formula (1), R ¹ represents an organic group of 1 to 5 carbon atoms which may contain a hetero atom, R ² represents a hydrogen atom or may contain a hetero atom good C1-5 Represents an organic group.)

[Application Example 4]
The chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 3 can be used for polishing an aluminum film or an aluminum alloy film in a semiconductor device manufacturing process.

[Application Example 5]
One aspect of the chemical mechanical polishing method according to the present invention is:
Using the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 4, a step of polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device is included.

  According to the chemical mechanical polishing aqueous dispersion according to the present invention, in the semiconductor device manufacturing process, it is possible to achieve both high polishing rate for aluminum film and its alloy film and suppression of pitting corrosion, and good storage stability. .

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.

1. Chemical mechanical polishing aqueous dispersion The chemical mechanical polishing aqueous dispersion according to one embodiment of the present invention includes (A) 0.1 to 10% by mass of abrasive grains and (B) 1 to 5 carbon atoms. A phosphoric acid ester compound having an organic group of 0.01 to 2% by mass, and having a pH of 1 to 4 inclusive. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion according to the present embodiment will be described in detail.

1.1. (A) Abrasive Grain The chemical mechanical polishing aqueous dispersion according to this embodiment contains (A) abrasive grains (hereinafter also referred to as “component (A)”). Examples of the component (A) include fumed silica, colloidal silica, ceria, alumina, zirconia, and titanium oxide. Among these, colloidal silica is preferable from the viewpoint of reducing polishing defects such as scratches. As the colloidal silica, 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.

  The average particle size of the component (A) can be determined by measuring the chemical mechanical polishing aqueous dispersion according to the present embodiment with a particle size distribution measuring apparatus based on the dynamic light scattering method. The average particle size of the component (A) is preferably 15 nm or more and 100 nm or less, and more preferably 30 nm or more and 70 nm or less. When the average particle size of the component (A) is in the above range, a practical polishing rate for the aluminum film can be achieved, and the water for chemical mechanical polishing excellent in storage stability in which the precipitation and separation of the component (A) are difficult to occur. A system dispersion can be obtained. 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 content ratio of the component (A) is 0.1% by mass or more and 10% by mass or less, preferably 0.2% by mass or more and 8% by mass or less, more preferably based on the total mass of the chemical mechanical polishing aqueous dispersion. It is 0.3 mass% or more and 7 mass% or less. When the content ratio of the component (A) is in the above range, a practical polishing rate for the aluminum film can be obtained. When the content ratio of the component (A) is less than the above range, the polishing rate for the aluminum film may be significantly reduced. On the other hand, when the content ratio of the component (A) exceeds the above range, the storage stability of the chemical mechanical polishing aqueous dispersion may deteriorate.

1.2. (B) Phosphate ester compound The chemical mechanical polishing aqueous dispersion according to the present embodiment is (B) a phosphate ester compound having an organic group having 1 to 5 carbon atoms (hereinafter also referred to as “component (B)”). ). In general, a phosphoric acid ester compound is a general term for compounds having a structure in which all or part of the three hydrogen atoms of phosphoric acid (O═P (OH) ₃ ) are substituted with organic groups. The component B) requires that the substituted organic group has 1 to 5 carbon atoms, preferably 1 to 4 and more preferably 2 to 3. When the carbon number of the organic group is within the above range, an appropriate protective film can be formed on the surface of the aluminum film to obtain a pitting corrosion suppressing effect and to obtain a practical polishing rate for the aluminum film. it can. When the carbon number of the organic group exceeds the above range, a protective film is formed on the surface of the aluminum film, but a pitting corrosion suppression effect is obtained, but the aluminum film surface is excessively protected, so a good polishing rate is obtained. Can't get.

  Specifically as said organic group, a C1-C5 aliphatic hydrocarbon group (for example, an alkyl group, an alkenyl group, an alkynyl group, etc.), a C3-C5 alicyclic hydrocarbon group (for example, A cycloalkyl group, a cycloalkenyl group, etc.), which may contain heteroatoms such as oxygen, sulfur, halogen and the like, and a part thereof may be substituted with other substituents.

  The component (B) is preferably at least one selected from phosphoric monoesters and phosphoric diesters. When the component (B) contains both phosphoric monoesters and phosphoric diesters, The content ratio is not particularly limited.

The component (B) is preferably a phosphoric acid monoester and / or a phosphoric acid diester represented by the following general formula (1).
(R ¹ O) (R ² O) —PO (OH) (1)
The formula (1), R ¹ represents an organic group of 1 to 5 carbon atoms which may contain a hetero atom, a carbon - may have a carbon-carbon double bond. R ² represents a hydrogen atom or an organic group having 1 to 5 carbon atoms which may contain a hetero atom, and may have a carbon-carbon double bond. Incidentally, the organic group of ^{R 1} and ^{R 2} is preferably 1 to 4 carbon atoms, and more preferably 2 to 3 carbon atoms. Examples of the hetero atom include oxygen, sulfur, halogen and the like. When the hetero atom is oxygen or sulfur, ether or thioether may be formed. Moreover, when (B) component is a polyvalent ester, it is preferable that the total number of carbon atoms contained in a plurality of organic groups does not exceed 5.

  Specific examples of such component (B) include monomethyl phosphate, monoethyl phosphate, mono-n-propyl phosphate, monoisopropyl phosphate, mono-n-butyl phosphate, monoisobutyl phosphate, monophosphate. -Phosphoric acid monoesters such as n-pentyl and monoisopentyl phosphate; and phosphoric acid diesters such as diethyl phosphate, dipropyl phosphate, dibutyl phosphate and dipentyl phosphate. The component (B) exemplified above may be used alone or in combination of two or more at any ratio.

  (B) The content rate of a component is 0.01 mass% or more and 2 mass% or less with respect to the total mass of the aqueous dispersion for chemical mechanical polishing, More preferably, it is 0.1 mass% or more and 1 mass% or less. When the content ratio of the component (B) is within the above range, the effect of suppressing pitting corrosion of the aluminum film can be obtained, and a practical polishing rate for the aluminum film can be obtained. When the content rate of (B) component is less than the said range, since a sufficient protective film cannot be formed on the surface of an aluminum film, a pitting corrosion suppression effect is not acquired. On the other hand, when the content ratio of the component (B) exceeds the above range, a pitting corrosion suppression effect due to the formation of a protective film on the surface of the aluminum film can be obtained, but the aluminum film surface is protected excessively, which is favorable. The polishing rate cannot be obtained. In addition, the storage stability of the chemical mechanical polishing aqueous dispersion may deteriorate.

1.3. Dispersion medium The chemical mechanical polishing aqueous dispersion according to the present embodiment contains a dispersion medium. Examples of the dispersion 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.

1.4. Other Additives The chemical mechanical polishing aqueous dispersion according to the present embodiment may further contain additives such as a pH adjuster, a surfactant, a water-soluble polymer, and an oxidizing agent as necessary. Hereinafter, each additive will be described.

1.4.1. pH adjuster The chemical mechanical polishing aqueous dispersion according to the present embodiment may further contain a pH adjuster as necessary. By appropriately adding a pH adjuster, the pH of the chemical mechanical polishing aqueous dispersion can be adjusted to 1 or more and 4 or less. Examples of the pH adjuster include acidic compounds and / or basic compounds.

  Examples of acidic compounds include organic acids and inorganic acids. Examples of the organic acid include malonic acid, maleic acid, citric acid, malic acid, tartaric acid, oxalic acid, lactic acid, and the like, and salts thereof. Examples of the inorganic acid include phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid and the like. The acidic compounds exemplified above may be used singly or in combination of two or more.

  Examples of the basic compound include potassium hydroxide, ethylenediamine, TMAH (tetramethylammonium hydroxide), ammonia and the like.

1.4.2. Surfactant The chemical mechanical polishing aqueous dispersion according to the present embodiment may further contain a surfactant as necessary. The surfactant has an effect of imparting an appropriate viscosity to the chemical mechanical polishing aqueous dispersion. 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 carboxylates such as fatty acid soaps and alkyl ether carboxylates; sulfonates such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, and α-olefin sulfonates; higher alcohol sulfates Examples thereof include sulfates such as ester salts, alkyl ether sulfates and polyoxyethylene alkylphenyl ether sulfates; and fluorine-containing surfactants such as perfluoroalkyl compounds. Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts. Examples of the nonionic surfactant include nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol; polyethylene glycol type surfactants. Polyvinyl alcohol, cyclodextrin, polyvinyl methyl ether, hydroxyethyl cellulose and the like can also be used. 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 0.001% by mass or more and 5% by mass or less, more preferably 0.001% by mass or more and 3% by mass or less, particularly with respect to the total mass of the chemical mechanical polishing aqueous dispersion. Preferably they are 0.01 mass% or more and 1 mass% or less.

1.4.3. Water-soluble polymer The chemical mechanical polishing aqueous dispersion according to the present embodiment may further contain a water-soluble polymer, if necessary. This water-soluble polymer has an effect of imparting an appropriate viscosity to the chemical mechanical polishing aqueous dispersion. Further, by forming a film by adsorbing to the surface of the surface to be polished, there is an effect of suppressing the occurrence of dishing and the like and further improving the flatness of the surface to be polished.

  Examples of the water-soluble polymer include an anionic polymer, a cationic polymer, and a nonionic polymer. Examples of the anionic polymer include polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, and salts thereof. Examples of the cationic polymer include polyethyleneimine, polyvinyl pyrrolidone, and polyvinyl imidazole. Examples of nonionic polymers include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, and polyacrylamide. These water-soluble polymers may be used alone or in combination of two or more.

  The weight average molecular weight of the water-soluble polymer is preferably 2,000 or more and 1,200,000 or less, more preferably 10,000 or more and 800,000 or less. In the present invention, the “weight average molecular weight” means a polystyrene-reduced weight average molecular weight measured by gel permeation chromatography.

  The content ratio of the water-soluble polymer is preferably 0.002% by mass to 5% by mass, more preferably 0.05% by mass to 1% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion. is there.

1.4.4. Oxidizing agent The chemical mechanical polishing aqueous dispersion according to the present embodiment may further contain an oxidizing agent as necessary. The oxidizing agent has the effect of creating a fragile modified layer on the surface of the aluminum film and facilitating polishing by oxidizing the surface of the aluminum film and promoting a complexing reaction with the polishing liquid component.

  Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, ferric nitrate, diammonium cerium nitrate, iron sulfate, hypochlorous acid, ozone, potassium periodate, and peracetic acid. These oxidizing agents may be used individually by 1 type, and may be used in combination of 2 or more type. Of these oxidizing agents, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferable in view of oxidizing power, compatibility with the protective film, ease of handling, and the like.

  The content of the oxidizing agent is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, and particularly preferably based on the total mass of the chemical mechanical polishing aqueous dispersion. Is 0.2 mass% or more and 1.5 mass% or less.

1.5. pH
The pH of the chemical mechanical polishing aqueous dispersion according to the present embodiment is 1 or more and 4 or less, preferably 1.5 or more and 3 or less, more preferably 1.8 or more and 2.5 or less. When the pH is in the above range, a practical polishing rate for the aluminum film can be achieved. When pH exceeds the said range, the polishing rate with respect to an aluminum film may fall remarkably.

1.6. Applications The chemical mechanical polishing aqueous dispersion according to the present embodiment can achieve a practical polishing rate for an aluminum film and an aluminum alloy film as described above, and also has a pitting corrosion suppression effect on the surface of the aluminum film and the aluminum alloy film. Have. Therefore, the chemical mechanical polishing aqueous dispersion according to the present embodiment is a polishing for chemical mechanical polishing of a substrate having an aluminum film and / or an aluminum alloy film that forms wiring of a semiconductor device in a manufacturing process of the semiconductor device. Suitable as a material. In the present invention, “aluminum alloy” refers to an alloy containing 90% by mass or more of aluminum and another metal element. Examples of other metal elements include Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti.

1.7. Method for Preparing Chemical Mechanical Polishing Aqueous Dispersion The chemical mechanical polishing aqueous dispersion according to the present embodiment can be prepared by dissolving or dispersing each component described above in a dispersion 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.

  In addition, the chemical mechanical polishing aqueous dispersion according to the present embodiment can be prepared as a concentrated stock solution and diluted with a dispersion 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 polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device using the chemical mechanical polishing aqueous dispersion described above. Including. Hereinafter, a specific example of the chemical mechanical polishing aqueous dispersion 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 aluminum film 14 is deposited by sputtering so as to fill the wiring recess 20, the workpiece 100 is obtained.

2.2. Polishing Step Using the chemical mechanical polishing aqueous dispersion described above, the aluminum film 14 deposited on the silicon oxide film 12 of the object 100 is polished and removed, and the entire surface is flattened to form an aluminum wiring portion. . According to the chemical mechanical polishing method according to the present embodiment, by using the chemical mechanical polishing aqueous dispersion described above, the polishing rate for the aluminum film 14 is sufficiently high, and pitting corrosion occurs on the surface of the aluminum film 14. Can be suppressed.

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-described polishing step, the carrier holding the semiconductor substrate 50 while supplying the slurry (chemical mechanical polishing aqueous dispersion) 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 the head 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 aqueous dispersion) 44 supplied from the slurry supply nozzle 42 can be selected within a 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. In the examples, “parts” and “%” are based on mass unless otherwise specified.

3.1. Preparation of aqueous dispersion containing abrasive grains 3.1.1. Preparation of aqueous dispersion containing colloidal silica A flask having a capacity of 2000 cm ³ was charged with 70 g of 25 mass% ammonia water, 40 g of ion-exchanged water, 175 g of ethanol and 21 g of tetraethoxysilane and heated to 60 ° C. while stirring at 180 rpm. Warm up. The mixture was stirred at 60 ° C. for 1 hour and then cooled to obtain a colloidal silica / alcohol dispersion. Subsequently, the alcohol in the colloidal silica / alcohol dispersion was removed several times by adding an ion exchange water to the colloidal silica / alcohol dispersion at 80 ° C. by an evaporator to remove the alcohol in the colloidal silica / alcohol dispersion. A 15% aqueous dispersion was prepared. About the sample which took out a part of this water dispersion and diluted with ion-exchange water, using a dynamic light scattering type particle size distribution measuring apparatus (Horiba, Ltd., model “LB550”), the arithmetic average diameter was calculated as the average particle diameter. As a result, it was 60 nm. The colloidal silica thus prepared is referred to as “colloidal silica A” in this example.

3.1.2. Preparation of Aqueous Dispersion Containing Ceria Cerium carbonate was calcined at 750 ° C. for 4 hours, then mixed with ion-exchanged water, pulverized with a bead mill using zirconia beads, and dispersed for 72 hours. The obtained aqueous dispersion of ceria was allowed to stand, and an amount corresponding to 90% by mass of the supernatant was fractionated to obtain an aqueous dispersion containing 35.8% by mass of ceria. Ion exchange water was added to the obtained water dispersion having a ceria content of 35.8% by mass to adjust the ceria content to 5% by mass to prepare a 5% by mass ceria water dispersion. The pH at this time was 5.3.

3.2. Preparation of Chemical Mechanical Polishing Aqueous Dispersion Ion-exchanged water calculated so that the aqueous dispersion prepared above has a predetermined abrasive grain concentration was put into a polyethylene bottle having a capacity of 1000 cm ³ , and this was described in the table. The acidic compound or basic compound was added in an amount such that the pH shown in the table was reached, and the mixture was sufficiently stirred. Thereafter, the aqueous dispersion prepared above, the phosphate ester described in the table, the oxidizing agent, and other additives were added with stirring. Then, the chemical mechanical polishing aqueous dispersions of Examples 1 to 10 and Comparative Examples 1 to 10 were obtained by filtering with a filter having a pore diameter of 5 μm. In addition, the value in a table | surface represents the net compounding quantity.

3.3. Evaluation method 3.3.1. Chemical Mechanical Polishing Test Using the chemical mechanical polishing aqueous dispersion prepared above, chemical mechanical polishing was performed under the following polishing conditions using an aluminum film having a diameter of 8 inches as an object to be polished.
<Polishing conditions>
・ Polishing device: Ebara Manufacturing Co., Ltd., model “EPO-112”
Polishing pad: Rodel Nitta Co., Ltd. “IC1000 / K-Groove”
・ Chemical mechanical polishing aqueous dispersion supply speed: 200 mL / min ・ Surface plate rotation speed: 90 rpm
-Polishing head rotation speed: 91 rpm
・ Polishing head pressing pressure: 140 hPa

3.3.1.1. Calculation of polishing rate of aluminum film For an aluminum film having a diameter of 8 inches, which is an object to be polished, the film thickness before polishing is measured in advance using a metal film thickness meter “Omnimap A-RS75tc” manufactured by KLA-Tencor. Then, polishing was performed for 1 minute under the above conditions. The film thickness of the polished object after polishing was similarly measured using a metal film thickness meter, and the difference between the film thickness before and after polishing, that is, the film thickness reduced by chemical mechanical polishing was determined. Then, the polishing rate was calculated from the film thickness decreased by chemical mechanical polishing and the polishing time. The evaluation criteria are as follows. The polishing rate and evaluation results of the aluminum film are also shown in Tables 1 and 2.
“◯”: The polishing rate exceeds 10 nm / min.
“X”: The polishing rate is 10 nm / min or less.

3.3.1.2. Evaluation of Pitting Corrosion An aluminum film having a diameter of 8 inches, which is an object to be polished, was polished for 1 minute under the above conditions, and then the substrate was sequentially washed and dried. After drying, the substrate surface was observed using an optical microscope to determine the presence or absence of fine pitting corrosion. The evaluation criteria are as follows. The evaluation results are also shown in Tables 1 and 2.
“◯”: No fine pitting corrosion is observed.
"X": A fine pitting corrosion is recognized.

3.3.2. Evaluation of Storage Stability 500 cc of the chemical mechanical polishing aqueous dispersion prepared above was placed in a 500 cc plastic bottle and stored for one day in an environment at 25 ° C. The appearance after storage was visually observed. The evaluation criteria are as follows. The evaluation results are also shown in Tables 1 and 2.
“◯”: No settling of abrasive grains is observed.
"X": Abrasive grain settling is observed.

In addition, the abbreviation of each component in Tables 1 and 2 is as follows.
・ Isopropyl phosphate (Takemoto Yushi Co., Ltd., product name “Pionin A76”)
-Diethyl phosphate (Johoku Chemical Co., Ltd., product name "JP-502")
・ Ethyl phosphate (Johoku Chemical Co., Ltd., product name “JAMP-2”)
・ Butyl phosphate (Johoku Chemical Co., Ltd., product name “JAMP-4”)
・ Octyl phosphate (product name “Pionin A-70” manufactured by Takemoto Yushi Co., Ltd.)

3.4. Evaluation Results In Examples 1 to 10, it was found that no pitting corrosion was observed on the surface of the aluminum film as the object to be polished, and a good polishing rate for the aluminum film was obtained.

  Comparative Example 1 is an example in which benzotriazole known as a copper film anticorrosive is used in place of the component (B). In such a case, although a good polishing rate for the aluminum film was obtained, the occurrence of pitting corrosion was observed on the surface of the aluminum film.

  Comparative Example 2 is an example in which a chemical mechanical polishing aqueous dispersion containing no component (B) was used. In such a case, although a good polishing rate for the aluminum film was obtained, the occurrence of pitting corrosion was observed on the surface of the aluminum film.

  Comparative Example 3 is an example in which a chemical mechanical polishing aqueous dispersion containing no component (A) was used. In such a case, the polishing rate for the aluminum film was significantly reduced.

  Comparative Examples 4 to 5 are examples using the chemical mechanical polishing aqueous dispersion in which the content of the component (B) is outside the specified range. When the component (B) is less than the specified range, a lot of pitting corrosion occurs. When the component (B) exceeds the specified range, the polishing rate for the aluminum film is remarkably reduced and the chemical mechanical polishing aqueous dispersion is used. The storage stability of the body also deteriorated.

  Comparative Example 6 is an example using a phosphate ester compound having an organic group having 8 carbon atoms. In such a case, although the occurrence of pitting corrosion was suppressed, the polishing rate for the aluminum film was remarkably reduced, and the storage stability of the chemical mechanical polishing aqueous dispersion was also deteriorated.

  Comparative Examples 7 to 8 are examples in which the chemical mechanical polishing aqueous dispersion having a component (A) content outside the specified range was used. When the component (A) was less than the specified range, the polishing rate for the aluminum film was remarkably reduced. When the component (A) exceeded the specified range, the storage stability of the chemical mechanical polishing aqueous dispersion deteriorated.

  Comparative Examples 9 to 10 are examples using a chemical mechanical polishing aqueous dispersion having a pH outside the specified range. In the neutral to alkaline region, although the occurrence of pitting corrosion was suppressed, the polishing rate for the aluminum film was significantly reduced.

  From the above results, it is clear that the chemical mechanical polishing aqueous dispersion according to the present invention can achieve both a high polishing rate for an aluminum film and suppression of pitting corrosion, and also has good storage stability. It was. Thus, it has been found that good polishing performance can be obtained in a semiconductor device including an aluminum film.

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.

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

Claims (5)

A chemical mechanical polishing aqueous dispersion used for polishing an aluminum film or an aluminum alloy film in a manufacturing process of a semiconductor device,
(A) 0.1% by mass or more and 10% by mass or less of silica ;
(B) 0.01 to 1 % by mass of a phosphoric acid ester compound having an organic group having 1 to 5 carbon atoms;
An aqueous dispersion for chemical mechanical polishing having a pH of 1 or more and 2.4 or less.   The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the (B) phosphate ester compound contains at least one selected from a phosphate monoester and a phosphate diester. The chemical mechanical polishing aqueous dispersion according to claim 1 or 2, wherein the (B) phosphate ester compound is a compound represented by the following general formula (1).
(R ¹ O) (R ² O) —PO (OH) (1)
In (the above formula (1), R ¹ represents an organic group of 1 to 5 carbon atoms which may contain a hetero atom, R ² represents a hydrogen atom or may contain a hetero atom good C1-5 Represents an organic group.) (B) The phosphoric acid ester compound is monomethyl phosphate, monoethyl phosphate, mono-n-propyl phosphate, monoisopropyl phosphate, mono-n-butyl phosphate, monoisobutyl phosphate, mono-n-phosphate 4. The method according to claim 1, which is at least one selected from the group consisting of pentyl, monoisopentyl phosphate, diethyl phosphate, dipropyl phosphate, dibutyl phosphate and dipentyl phosphate. An aqueous dispersion for chemical mechanical polishing.   5. A chemical mechanical polishing comprising a step of polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device, using the chemical mechanical polishing aqueous dispersion according to claim 1. Method.

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