JP6638208B2 - Abrasive, storage solution for abrasive and polishing method - Google Patents

Description

  The present invention relates to a polishing slurry for tungsten, a stock solution for the polishing slurry for obtaining the polishing slurry, and a polishing method using the polishing slurry.

  2. Description of the Related Art In recent years, a new fine processing technology has been developed in accordance with high integration or high performance of a semiconductor integrated circuit (hereinafter, referred to as “LSI”). Chemical mechanical polishing (hereinafter, referred to as “CMP”) is one of them. CMP is an LSI manufacturing process (particularly, planarization of an interlayer insulating film, formation of a metal plug, formation of a buried wiring, and the like in a multilayer wiring forming process). This is a technology that is frequently used in

  The formation of the buried wiring using the CMP method will be described. First, a stacked body including a substrate having pre-formed irregularities on its surface and an interlayer insulating film (such as an oxide film) stacked on the substrate is prepared. Next, a barrier metal film (such as a titanium nitride film) is deposited on the entire surface of the interlayer insulating film. Further, a wiring metal film of a tungsten material film (tungsten film, tungsten alloy film, or the like) is deposited on the entire barrier metal film so as to fill the recesses (grooves). Next, the unnecessary wiring metal film other than the concave portion and the underlying barrier metal film are removed by CMP to form a buried wiring. Such a wiring forming method is called a damascene method (for example, see Patent Document 1 below).

  A general method of CMP of a metal film is to attach a polishing cloth (polishing pad) on a circular polishing platen (platen) and immerse the surface of the polishing cloth with a metal film polishing agent while polishing the metal film on the substrate. The formed surface is pressed against the polishing cloth, and the polishing platen is rotated while a predetermined pressure (polishing pressure, polishing load) is applied to the metal film from the back surface of the polishing cloth. This is to remove the metal film on the convex portion by the mechanical friction.

  The polishing agent for metal film used in CMP generally contains an oxidizing agent, solid abrasive grains and water, and further contains a metal oxide dissolving agent, a metal anticorrosive, and the like as necessary. When polishing using such an abrasive, first, the metal film surface is oxidized by the oxidizing agent to form an oxide layer, and it is considered that a basic mechanism is to scrape the oxide layer with solid abrasive grains. I have. The oxide layer on the surface of the metal film embedded in the concave portion does not touch the polishing cloth so much that the effect of the scraping by the solid abrasive grains does not reach, so the oxide layer of the metal layer on the convex portion is removed with the progress of CMP. The substrate surface is flattened (for example, see Non-Patent Document 1 below).

  As a polishing step in forming a damascene wiring using a tungsten material film (tungsten film, tungsten alloy film, etc.), a rough polishing step of polishing most of the tungsten material film, and a polishing of a tungsten material film, an insulating film, and a barrier metal film. The mainstream is a two-step process including a finish polishing step.

  FIG. 1 is a schematic cross-sectional view for explaining wiring formation by a general damascene method. FIG. 1A shows a state of an object to be polished before rough polishing. The objects to be polished before the rough polishing are an insulating film 1 having an uneven surface, a barrier layer 2 formed to follow the unevenness of the surface of the insulating film 1, and a wiring metal deposited to fill the unevenness. (Tungsten materials such as tungsten and tungsten alloy).

  First, as shown in FIG. 1B, polishing is performed with a polishing agent for rough polishing until the projections of the insulating film 1 are exposed. Next, as shown in FIG. 1C, the insulating film 1 and the wiring metal 3 are polished with a polishing agent for finish polishing so as to be flat.

  When a tungsten polishing agent (tungsten material polishing agent) is used as a rough polishing polishing agent, the polishing rate of the tungsten material is much higher than the polishing rate of the insulating material. A phenomenon called "erosion" in which the insulating material is excessively polished occurs, and the flatness is reduced. As a result, a problem such as an increase in wiring resistance occurs, so that it is required to reduce erosion as much as possible in the finish polishing step.

  Examples of the CMP polishing agent for tungsten for solving the above problem include polishing agents described in Patent Documents 2 to 4 below.

  Patent Literature 2 describes an abrasive containing abrasive grains, periodic acid, ammonium nitrate, and ammonia. This abrasive reduces erosion by adjusting the pH with ammonia and adjusting the polishing rate of the tungsten film and the insulating film to an appropriate range.

  Patent Literature 3 describes an abrasive containing two types of abrasive grains, fumed silica and colloidal silica, and an oxidizing agent. This polishing agent adjusts the polishing rate of the tungsten film and the insulating film to an appropriate range by adjusting the mixing ratio of fumed silica and colloidal silica.

  Patent Document 4 describes an abrasive containing abrasive grains, iron ions, and a polymer having an imidazole ring. This abrasive uses an polymer having an imidazole ring to reduce the etching rate of the tungsten film and reduce erosion.

U.S. Pat. No. 4,944,836 Japanese Patent No. 4083528 Japanese Patent No. 5321987 Japanese Patent No. 5628990

Journal of Electrochemical Society, Vol. 138, No. 11, 1991, pp. 3460-3364.

  However, the polishing agent described in Patent Document 2 has a problem that erosion is difficult to reduce due to a strong corrosive effect of periodic acid on the tungsten film, and erosion is not sufficiently reduced only by adjusting the polishing rate. Even with the polishing agent described in Patent Document 3, there is a problem that erosion is not sufficiently reduced only by adjusting the polishing rate. Furthermore, in the polishing agent described in Patent Document 4, the effect of reducing the etching rate by using a polymer having an imidazole ring is not sufficient, and erosion cannot be sufficiently suppressed, or the polishing rate of the tungsten film is reduced. There's a problem.

  The present invention has been made in view of the above problems, and has as its object to provide a tungsten polishing agent that can reduce erosion while maintaining a good polishing rate for a tungsten material. Another object of the present invention is to provide a stock solution for an abrasive for obtaining the above-mentioned abrasive, and a polishing method using the above-mentioned abrasive.

  The present inventors have conducted intensive studies and found that, by using an abrasive containing 0.1 to 2.0% by mass of a specific polysaccharide having a weight average molecular weight of 5,000 to 250,000, a favorable tungsten material can be obtained. It has been found that erosion can be reduced while maintaining the polishing rate.

An abrasive for tungsten according to an embodiment of the present invention contains abrasive grains, an oxidizing agent, and a polysaccharide having a structural unit represented by the following formula (I), and the weight average molecular weight of the polysaccharide is 5000 to 250,000, and the content of the polysaccharide is 0.1 to 2.0% by mass based on the total mass of the abrasive.
(C ₆ H ₁₀ O ₅ ) (I)

  According to the polishing slurry for tungsten according to the embodiment of the present invention, a high polishing rate of a tungsten material and a low etching rate of a tungsten material can be highly compatible, and a good polishing rate for a tungsten material is maintained. Erosion can be reduced while doing so. According to such an abrasive, the flatness of the polished surface after polishing can be improved. In particular, according to the abrasive for tungsten according to the embodiment of the present invention, when forming an embedded wiring containing a tungsten material, erosion can be reduced while maintaining a favorable polishing rate for the tungsten material.

  The polysaccharide preferably contains at least one selected from the group consisting of dextrin and dextran. In this case, erosion can be easily reduced while maintaining a good polishing rate for the tungsten material.

  The abrasive preferably contains silica. In this case, the effect of reducing polishing scratches while maintaining a high polishing rate for the tungsten material can be obtained.

  The silica is preferably colloidal silica. In this case, the effect of reducing polishing scratches while maintaining a high polishing rate for the tungsten material can be obtained.

  The pH of the polishing slurry according to the embodiment of the present invention is preferably 2.0 to 6.0. In this case, an effect of sufficiently improving the polishing rate of the tungsten material and the insulating material and an effect of suppressing a decrease in the liquid stability of the abrasive due to dissolution of the abrasive grains can be obtained.

  The abrasive according to the embodiment of the present invention may further contain a (meth) acrylic acid-based polymer.

  The (meth) acrylic acid-based polymer is a homopolymer of acrylic acid, a homopolymer of methacrylic acid, or a copolymer obtained by polymerizing a composition containing acrylic acid and methacrylic acid as monomer components. It is preferably at least one selected from the group consisting of coalescence. In this case, erosion can be easily reduced while maintaining a good polishing rate for the tungsten material.

  The polishing agent according to the embodiment of the present invention may be used for polishing a surface to be polished including a tungsten material and at least one selected from the group consisting of a barrier material and an insulating material.

  The stock solution for an abrasive according to the embodiment of the present invention is a stock solution for an abrasive for obtaining the above-mentioned abrasive, and is obtained by diluting with water. According to such a stock solution for an abrasive, costs, space, and the like required for transporting and storing the abrasive can be reduced.

  The polishing method according to the embodiment of the present invention includes the step of polishing the surface to be polished using the polishing slurry according to the embodiment of the present invention or the polishing slurry obtained from the stock solution for polishing according to the embodiment of the present invention. Is provided. The polished surface may include a tungsten material.

  According to the present invention, erosion can be reduced while maintaining a good polishing rate for a tungsten material. In particular, according to the present invention, when forming a buried wiring containing a tungsten material (for example, by using a CMP method), erosion can be reduced while maintaining a favorable polishing rate for the tungsten material.

  According to the present invention, it is possible to provide an application of an abrasive to polishing of a tungsten material. ADVANTAGE OF THE INVENTION According to this invention, the application of an abrasive to formation of the embedded wiring containing a tungsten material can be provided. According to the present invention, it is possible to provide an application of an abrasive for polishing a surface to be polished having a tungsten material and at least one selected from the group consisting of a barrier material and an insulating material. According to the present invention, the final polishing in the process includes a rough polishing step of roughly polishing a tungsten material, and a final polishing step of polishing at least one selected from the group consisting of an insulating material and a barrier material. The application of the abrasive to the process can be provided.

FIG. 1 is a schematic cross-sectional view for explaining wiring formation by a damascene method. FIG. 2 is a schematic cross-sectional view for explaining erosion in a stripe-shaped pattern portion (a portion where a wiring metal portion and an insulating film portion are alternately arranged) of a pattern substrate with tungsten wiring.

  Hereinafter, embodiments of the present invention will be described.

<Definition>
In the present specification, “(meth) acrylic acid” means at least one of acrylic acid and methacrylic acid. The term "step" is included in the term as well as an independent step, even if it is not clearly distinguishable from other steps, provided that the intended action of that step is achieved. The numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. When there are a plurality of substances corresponding to each component in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified. “Polishing Rate” means the rate at which material is removed per unit time (removal rate = Removal Rate). The terms “layer” and “film” include, when observed as a plan view, a structure partially formed in addition to a structure formed over the entire surface.

  As used herein, the term “abrasive for tungsten” means an abrasive for polishing a tungsten material. The “tungsten material” means a material containing 50 mol% or more of tungsten, and includes tungsten, a tungsten alloy, a tungsten compound (for example, tungsten oxide, tungsten silicide, and tungsten nitride).

  In the present specification, dilution by a factor of X is defined as that the mass of the polishing slurry becomes X times the mass of the original polishing stock by adding water to the polishing slurry. . For example, obtaining an abrasive by adding the same mass of water to the mass of the stock solution for an abrasive is defined as diluting twice.

<Abrasive>
The polishing agent according to the present embodiment is a polishing agent for tungsten (a polishing agent for a tungsten material such as a polishing agent for tungsten or a tungsten alloy). The abrasive according to the present embodiment is a composition that comes into contact with the surface to be polished during polishing, and is, for example, an abrasive for CMP. The abrasive according to the present embodiment contains abrasive grains, an oxidizing agent, and a polysaccharide having a structural unit represented by the following formula (I), and the polysaccharide has a weight average molecular weight of 5,000 to 250,000. The content of the polysaccharide is 0.1 to 2.0% by mass based on the total mass of the abrasive.
(C ₆ H ₁₀ O ₅ ) (I)

Erosion can be reduced by removing the tungsten material of the wiring metal using the abrasive according to the present embodiment. Although the reason for this is not clear, in the abrasive according to the present embodiment, the hydroxyl group in the polysaccharide having the structural unit represented by the formula (I) is converted into tungsten oxide obtained by oxidizing a tungsten material with an oxidizing agent. This is probably because a complex was formed with an oxo acid such as tungstic acid (H ₂ WO ₄ ) generated due to this. Since this complex functions as a film for protecting the tungsten material and an oxide film near the tungsten material, it is considered that a portion of the surface to be polished that is not protected by the complex is preferentially removed, and erosion is reduced.

  Hereinafter, components and the like contained in the abrasive according to the present embodiment will be described in more detail.

(Abrasive)
The abrasive according to the present embodiment contains abrasive grains. Examples of the constituent material of the abrasive grains include silica, alumina, ceria, zirconia, cerium hydroxide, and resin particles.

  The abrasive preferably contains silica. It is considered that the abrasive containing silica has a higher affinity for the tungsten material than other types of abrasive, and the frequency of contact with the tungsten material increases. Therefore, it is considered that the polishing rate of the tungsten material is easily improved by using the abrasive containing silica. Further, by using abrasive grains containing silica, an effect of reducing polishing scratches while maintaining a high polishing rate for a tungsten material can be obtained.

  Examples of the silica include colloidal silica and fumed silica. Above all, as silica, the viewpoint that the polishing rate of the tungsten material tends to be further increased, the viewpoint that polishing scratches (refer to the scratches appearing on the surface after polishing; the same applies hereinafter), and the selection of the particle size are easy. From the viewpoint, colloidal silica is preferred. The abrasive grains may be particles made of silica (silica particles).

  Abrasive grains can be used alone or in combination of two or more. For example, an abrasive containing silica and an abrasive containing other than silica can be used in combination.

  The average particle diameter of the abrasive grains in the abrasive is preferably 10 nm or more, more preferably 30 nm or more, and 40 nm or more from the viewpoint that the mechanical polishing force is sufficient and the polishing rate of the tungsten material and the insulating material tends to be further increased. Is more preferred. The average particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 120 nm or less, and still more preferably 90 nm or less, from the viewpoint of good dispersion stability of the abrasive grains. In addition, also when using the abrasive grain containing things other than silica as an abrasive grain, it is preferable to use the abrasive grain which satisfies the said average particle diameter.

  The average particle size of the abrasive grains can be measured by a photon correlation method. Specifically, for example, the average particle diameter can be measured using a device name: Zetasizer 3000HS manufactured by Malvern Instruments, a device name: N5 manufactured by Beckman Coulter, or the like. The measuring method using N5 is as follows. Specifically, for example, an aqueous dispersion in which the content of abrasive grains is adjusted to 0.2% by mass is prepared, and about 4 mL of this aqueous dispersion is placed in a 1 cm square cell (L indicates "liter". The same applies hereinafter). ), And install the cell in the device. The value obtained by setting the refractive index of the dispersion medium to 1.33 and the viscosity to 0.887 mPa · s and performing the measurement at 25 ° C. can be used as the average particle diameter of the abrasive grains.

  The content of the abrasive grains containing silica should be more than 50% by mass based on the total mass of the abrasive grains, from the viewpoint of achieving a higher level of both the effect of reducing the polishing scratches and the effect of improving the polishing rate of the tungsten material. Is preferably 60% by mass or more, more preferably 70% by mass or more, particularly preferably 80% by mass or more, particularly preferably 90% by mass or more, and very preferably 95% by mass or more. The upper limit of the content of the abrasive grains containing silica is, for example, 100% by mass based on the total mass of the abrasive grains.

  The content of the abrasive grains containing silica is 0.4% by mass or more based on the total mass of the polishing agent, from the viewpoint that the mechanical polishing force becomes sufficient and the polishing rate of the tungsten material and the insulating material tends to be further increased. Is preferably 0.6% by mass or more, more preferably 0.8% by mass or more. The content of the abrasive grains containing silica is polished from the viewpoint that the viscosity of the abrasive is easily increased, the agglomeration of the abrasives is easily avoided, the abrasive scratch is easily reduced, and the handling of the abrasive is easy. It is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less, particularly preferably 4% by mass or less, based on the total mass of the agent.

  The content of the abrasive grains is preferably 0.4% by mass or more based on the total mass of the abrasive, from the viewpoint that the mechanical polishing force becomes sufficient and the polishing rate of the tungsten material and the insulating material tends to be further increased. 0.6 mass% or more is more preferable, and 0.8 mass% or more is still more preferable. The content of the abrasive is determined by considering the viewpoint that the viscosity of the abrasive is easily increased, the agglomeration of the abrasive is easily avoided, the abrasive scratch is easily reduced, and the handling of the abrasive is easy. It is preferably 15% by mass or less, more preferably 10% by mass or less, further preferably 7% by mass or less, particularly preferably 4% by mass or less, based on the mass.

(Oxidant)
The polishing agent according to the present embodiment contains an oxidizing agent. Examples of the oxidizing agent include hydrogen peroxide; peracetic acid; perbenzoic acid; permanganate compounds such as potassium permanganate; and ammonium persulfate. Hydrogen peroxide is preferred over other types of oxidizing agents because they are inexpensive and can be supplied in liquid form. The oxidizing agent can be used alone or in combination of two or more.

  The content of hydrogen peroxide is preferably more than 50% by mass, more preferably 60% by mass or more, based on the total mass of the oxidizing agent, from the viewpoint that the effect of improving the polishing rate of the tungsten material is easily obtained. It is more preferably at least 80% by mass, particularly preferably at least 80% by mass, very preferably at least 90% by mass, and very preferably at least 95% by mass. The upper limit of the content of hydrogen peroxide is, for example, 100% by mass based on the total mass of the oxidizing agent.

  The content of the oxidizing agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the polishing agent, from the viewpoint that the effect of improving the polishing rate of the tungsten material is easily obtained. 1% by mass or more is more preferable. The content of the oxidizing agent is preferably 10% by mass or less, more preferably 7% by mass or less based on the total mass of the polishing agent, from the viewpoint of easily suppressing the progress of etching of the tungsten material and easily controlling the polishing rate of the tungsten material. Is more preferable, and 4% by mass or less is further preferable. From these viewpoints, the content of the oxidizing agent is preferably from 0.1 to 10% by mass, more preferably from 0.5 to 7% by mass, and still more preferably from 1 to 4% by mass, based on the total mass of the abrasive. .

(Polysaccharide)
The abrasive according to the present embodiment contains a polysaccharide having a structural unit represented by the following formula (I). The polysaccharide only needs to have at least one structural unit represented by the formula (I). For example, the polysaccharide may be a compound comprising the structural unit represented by the formula (I) or a compound having the structural unit represented by the formula (I) in a part of the molecule. The polysaccharide having a structural unit represented by the formula (I) may have, for example, a hydroxyl group, or may have a hydroxyl group in a (C ₆ H ₁₀ O ₅ ) skeleton portion.
(C ₆ H ₁₀ O ₅ ) (I)

The polysaccharide may have a structural unit represented by the following general formula (Ia). n is preferably from 45 to 1400, more preferably from 60 to 1250, from the viewpoint that the effect of reducing erosion is easily obtained and the polishing rate of the tungsten material and the insulating material is further increased.
(C ₆ H ₁₀ O ₅ ) _n (Ia)
[In Formula (Ia), n represents 30 to 1500. ]

  Examples of the polysaccharide having the structural unit represented by the formula (I) include dextrin; maltodextrin; cyclodextrin such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The polysaccharide preferably contains at least one selected from the group consisting of dextrin and dextran, from the viewpoint that erosion can be easily reduced while maintaining a good polishing rate for the tungsten material.

  As the dextrin, dextrin having an aldehyde group at the terminal of a decomposed product obtained by decomposition of starch (also referred to as “general dextrin” for distinction from other dextrins); Indigestible dextrins obtained by purifying difficult dextrins; reduced dextrins in which the aldehyde terminals are reduced by hydrogenation to be converted into hydroxyl groups. Any of these compounds can be used as dextrin.

  The polysaccharide may be a water-soluble polysaccharide. “Water-soluble polysaccharide” is defined as a polysaccharide that is soluble in 0.01 g or more in 100 g of water at 25 ° C. Polysaccharides can be used alone or in combination of two or more.

  The weight average molecular weight of the polysaccharide (dextrin, dextran, etc.) is 5,000 to 250,000 from the viewpoint of reducing erosion while maintaining a good polishing rate for the tungsten material. The weight average molecular weight of the polysaccharide is preferably 7,500 or more, more preferably 10,000 or more, still more preferably 15,000 or more, and particularly preferably 20,000 or more, from the viewpoint of easily obtaining the effect of reducing erosion. The weight average molecular weight of the polysaccharide is preferably 225,000 or less, more preferably 200,000 or less, from the viewpoint of further increasing the polishing rate of the tungsten material and the insulating material. From these viewpoints, the weight average molecular weight of the polysaccharide is preferably 7500 to 225,000, more preferably 10,000 to 200,000, further preferably 15,000 to 200,000, and particularly preferably 20,000 to 200,000.

  The weight average molecular weight (Mw) can be measured using, for example, gel permeation chromatography (GPC) under the following conditions.

{conditions}
Sample: 10 μL
Standard polystyrene: manufactured by Tosoh Corporation, standard polystyrene (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266)
Detector: RI-Monitor, manufactured by Hitachi, Ltd., trade name "L-3000"
Integrator: GPC integrator manufactured by Hitachi, Ltd., product name "D-2200"
Pump: Hitachi Ltd., product name "L-6000"
Degassing device: Showa Denko Co., Ltd., trade name "Shodex DEGAS"
Column: Hitachi Chemical Co., Ltd., trade names "GL-R440", "GL-R430", and "GL-R420" used in this order. Eluent: tetrahydrofuran (THF)
Measurement temperature: 23 ° C
Flow rate: 1.75 mL / min Measurement time: 45 minutes

  The content of the polysaccharide (dextrin, dextran, etc.) is 0.1 to 2.0% by mass based on the total mass of the abrasive from the viewpoint of reducing erosion while maintaining a good polishing rate for the tungsten material. . The content of the polysaccharide is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and more preferably 0.4% by mass, based on the total mass of the abrasive, from the viewpoint of easily obtaining the effect of reducing erosion. % Or more, more preferably 0.5% by mass or more. The content of the polysaccharide is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, based on the total mass of the abrasive, from the viewpoint that the effect of improving the polishing rate of the tungsten material is easily obtained. From these viewpoints, the content of the polysaccharide is preferably from 0.2 to 2.0% by mass, more preferably from 0.3 to 1.5% by mass, and more preferably from 0.4 to 1.5% by mass, based on the total mass of the abrasive. 1.5 mass% is more preferable, and 0.5 to 1.0 mass% is particularly preferable.

((Meth) acrylic acid polymer)
The abrasive according to the present embodiment may contain a (meth) acrylic acid-based polymer ((meth) acrylic acid polymer). The (meth) acrylic acid polymer is a polymer having a structural unit derived from (meth) acrylic acid. As the (meth) acrylic acid-based polymer, for example, homopolymers of (meth) acrylic acid (polyacrylic acid and polymethacrylic acid), and compositions containing (meth) acrylic acid and other monomer components (A copolymer having a structural unit derived from (meth) acrylic acid; a copolymer of (meth) acrylic acid and another monomer component) obtained by polymerizing the product. Examples of the monomer component copolymerizable with (meth) acrylic acid include alkyl (meth) acrylates such as methyl (meth) acrylate. As the (meth) acrylic acid-based polymer, a homopolymer of acrylic acid, a homopolymer of methacrylic acid, and a viewpoint of easily reducing erosion while maintaining a good polishing rate for a tungsten material, and At least one selected from the group consisting of copolymers obtained by polymerizing a composition containing acrylic acid and methacrylic acid as monomer components (hereinafter, referred to as "acrylic acid / methacrylic acid copolymer") preferable. The composition for obtaining the acrylic acid / methacrylic acid copolymer may contain monomer components other than acrylic acid and methacrylic acid (methyl acrylate, methyl methacrylate, etc.).

  The copolymer having a structural unit derived from (meth) acrylic acid is converted into an amide group by using a monomer component having a functional group such as an amide group, a hydroxy group, a urea group, a carboxyl group, a methyl group, and a sulfo group. , A hydroxy group, a urea group, a carboxyl group, a methyl group, a sulfo group or the like. For example, the acrylic acid / methacrylic acid copolymer uses the monomer components other than acrylic acid and methacrylic acid to form an amide group, a hydroxy group, a urea group, a carboxyl group, a methyl group, a sulfo group, and the like. It may have a chain. The polymerization form of the (meth) acrylic acid-based polymer is not particularly limited, and examples thereof include a block copolymer and a random copolymer.

  When an acrylic acid / methacrylic acid copolymer is used, the copolymerization ratio of acrylic acid to methacrylic acid (molar ratio: acrylic acid / methacrylic acid) is not particularly limited, but is preferably from 1/99 to 95/5. The copolymerization ratio (acrylic acid / methacrylic acid) is from 1/99 to 40 / from the viewpoint of achieving a higher degree of compatibility between the high polishing rate of the tungsten material and the low etching rate of the tungsten material, and from the viewpoint of excellent solubility. 60 is more preferred.

  The (meth) acrylic acid-based polymer may be a water-soluble polymer. “Water-soluble polymer” is defined as a polymer that dissolves in an amount of 0.1 g or more per 100 g of water at 25 ° C. The (meth) acrylic acid-based polymer can be used alone or in combination of two or more.

  The weight average molecular weight of the (meth) acrylic acid-based polymer is preferably 1000 or more from the viewpoint that the etching rate of the tungsten material is easily suppressed. The weight average molecular weight of the (meth) acrylic acid-based polymer is preferably 2,000 or more, more preferably 4,000 or more, from the viewpoint of easily exhibiting a high polishing rate. The upper limit of the weight average molecular weight of the (meth) acrylic acid-based polymer is not particularly limited, but is preferably 5,000,000 or less, more preferably 1,000,000 or less, from the viewpoint of excellent solubility in the abrasive and storage stability of the abrasive. More preferably, it is even more preferably 500,000 or less. From these viewpoints, the weight average molecular weight of the (meth) acrylic acid-based polymer is preferably from 1,000 to 5,000,000.

  The weight average molecular weight (Mw) can be measured using, for example, gel permeation chromatography (GPC) under the following conditions.

{conditions}
Sample: 10 μL
Standard polystyrene: manufactured by Tosoh Corporation, standard polystyrene (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266)
Detector: RI-Monitor, manufactured by Hitachi, Ltd., trade name "L-3000"
Integrator: GPC integrator manufactured by Hitachi, Ltd., product name "D-2200"
Pump: Hitachi Ltd., product name "L-6000"
Degassing device: Showa Denko Co., Ltd., trade name "Shodex DEGAS"
Column: Hitachi Chemical Co., Ltd., trade names "GL-R440", "GL-R430", and "GL-R420" used in this order. Eluent: tetrahydrofuran (THF)
Measurement temperature: 23 ° C
Flow rate: 1.75 mL / min Measurement time: 45 minutes

  The content of the (meth) acrylic acid-based polymer is preferably 0.005% by mass or more, and more preferably 0.01% by mass or more based on the total mass of the abrasive, from the viewpoint of further improving the etching resistance of the tungsten material. More preferably, the content is more preferably 0.05% by mass or more. The content of the (meth) acrylic acid-based polymer is preferably 2% by mass or less, more preferably 1% by mass or less based on the total mass of the abrasive, from the viewpoint of further improving the polishing rate of the tungsten material and the insulating material. . From these viewpoints, the content of the (meth) acrylic acid-based polymer is preferably 0.005 to 2% by mass, more preferably 0.01 to 1% by mass, and more preferably 0.01 to 1% by mass, based on the total mass of the abrasive. The amount is more preferably from 0.5 to 1% by mass.

(Other additives)
The abrasive according to the present embodiment further contains additives other than the above components for the purpose of improving the dispersibility of the abrasive grains in the abrasive, improving the chemical stability of the abrasive, improving the polishing rate, and the like. be able to. Examples of such additives include an acid component, a corrosion inhibitor, an antifoaming agent, and the like. The content of the other additives in the abrasive can be arbitrarily determined as long as the properties of the abrasive are not impaired.

  The abrasive according to the present embodiment may contain an acid component. By controlling the pH with an acid component, the dispersibility, stability and polishing rate of the aqueous dispersion can be further improved. The acid component is, for example, at least one selected from the group consisting of organic acids and inorganic acids. The organic acid is not particularly limited, but is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid , N-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid , Pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid and the like. The inorganic acid is not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, nitric acid, and chromic acid. The acid component can be used alone or in combination of two or more.

  The abrasive according to the present embodiment may contain a corrosion inhibitor. By using the corrosion inhibitor, the etching resistance of the tungsten material can be further improved. The corrosion inhibitor is not particularly limited, and examples thereof include a compound having a triazole skeleton, a compound having an imidazole skeleton, a compound having a pyrimidine skeleton, a compound having a guanidine skeleton, a compound having a thiazole skeleton, and a compound having a pyrazole skeleton. Can be The corrosion inhibitors can be used alone or in combination of two or more.

  Compounds having a triazole skeleton include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxy Propylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl (-1H-) benzotriazole, 4-carboxyl (-1H-) benzotriazole methyl ester, 4-carboxyl (-1H -) Benzotriazole butyl ester, 4-carboxyl (-1H-) benzotriazole octyl ester, 5-hexyl benzotriazole, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] pho Acid, 3-aminotriazole, 5-methyl benzotriazole. Among these, 1,2,3-triazole, 1,2,4-triazole, and 3-amino-1H-, from the viewpoint of achieving a higher degree of compatibility between a high polishing rate of a tungsten material and a low etching rate of a tungsten material. Preferred are 1,2,4-triazole, 4-amino-4H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole and 5-methylbenzotriazole.

  Examples of the compound having an imidazole skeleton include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 4-ethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-aminoimidazole and the like can be mentioned.

  Examples of the compound having a pyrimidine skeleton include pyrimidine, [1,2,4] -triazolo [1,5-a] pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2 -A] pyrimidine, 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4 , 5-Trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4- Diamino-6-hydroxypyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 2-methyl-5,7-diphenyl- 1,2,4] triazolo [1,5-a] pyrimidine, 2-methylsulfanyl-5,7-diphenyl- [1,2,4] triazolo [1,5-a] pyrimidine, 2-methylsulfanyl -5,7-diphenyl-4,7-dihydro- [1,2,4] triazolo [1,5-a] pyrimidine, 4-aminopyrazolo [3,4-d] pyrimidine and the like.

  Examples of the compound having a guanidine skeleton include 1,3-diphenylguanidine, 1-methyl-3-nitroguanidine, and the like.

  Compounds having a thiazole skeleton include 2-mercaptobenzothiazole, 2-aminothiazole, 4,5-dimethylthiazole, 2-amino-2-thiazoline, 2,4-dimethylthiazole, 2-amino-4- Methylthiazole and the like.

  Examples of the compound having a pyrazole skeleton include 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole, 3-amino-5-hydroxypyrazole, and 3-amino-5-methylpyrazole. Is mentioned.

  The corrosion inhibitor is a compound having a triazole skeleton, and at least one selected from the group consisting of compounds having an imidazole skeleton, from the viewpoint of easily suppressing the etching of the tungsten material while maintaining a high polishing rate of the tungsten material. Is preferred.

  The content of the corrosion inhibitor is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, based on the total mass of the abrasive, from the viewpoint of further improving the etching resistance of the tungsten material. The content of the corrosion inhibitor is preferably 5% by mass or less, more preferably 3% by mass or less, based on the total mass of the abrasive, from the viewpoint that the effect of improving the polishing rate of the tungsten material is easily obtained. From these viewpoints, the content of the corrosion inhibitor is preferably 0.005 to 5% by mass, more preferably 0.01 to 3% by mass, based on the total mass of the abrasive.

(water)
The abrasive according to the present embodiment can contain water. Water is included to act as a dispersion medium or solvent for other components. The water is preferably free of impurities as much as possible in order to prevent the action of other components from being hindered. Specifically, pure water, ultrapure water, distilled water, and the like, in which foreign substances are removed through a filter after removing impurity ions with an ion exchange resin, are preferable.

(PH of abrasive)
The pH of the abrasive according to the present embodiment is preferably 2.0 or more, more preferably 2.1 or more, still more preferably 2.2 or more, and more preferably 2.4 or more, from the viewpoint of easily obtaining a mechanical polishing force. Particularly preferred. The pH of the abrasive is preferably 6.0 or less, more preferably 5.8 or less, and even more preferably 5.6 or less, from the viewpoint of good dispersion stability of the abrasive grains. The pH of the abrasive may be adjusted by, for example, the acid component; a base component such as ammonia, sodium hydroxide, potassium hydroxide, or TMAH (tetramethylammonium hydroxide). The pH is defined as the pH at a liquid temperature of 25 ° C.

  The pH of the abrasive can be measured by a pH meter using a general glass electrode. Specifically, for example, trade name: Model (F-51) of Horiba, Ltd. can be used. Using a phthalate pH standard solution (4.01), a neutral phosphate pH standard solution (pH 6.86), and a borate pH standard solution (pH 9.18) as pH standard solutions, a pH meter was used. After the three-point calibration, the pH can be obtained by putting the electrode of the pH meter in an abrasive and measuring the value after the lapse of 2 minutes or more and stabilization. At this time, the temperature of the pH standard solution (standard buffer solution) and the temperature of the polishing agent can be set to 25 ° C., for example.

  There is no particular limitation on the method for blending and diluting the abrasive according to the present embodiment, and for example, it is possible to prepare the abrasive by dispersing or dissolving each component by stirring with a blade-type stirrer, ultrasonic dispersion, or the like. it can. The order of mixing other components with water is not limited.

<Abrasive storage solution>
The abrasive according to the present embodiment can be stored as a storage solution that is diluted with water and used at the time of use, from the viewpoint of suppressing costs related to storage, transportation, storage, and the like. The abrasive according to the present embodiment is stored, for example, with a reduced amount of water than expected at the time of use, and is diluted with water (for example, diluted to 1.5 times or more by mass) before use, and the abrasive is used. Used as The stock solution according to the present embodiment is a stock solution for the abrasive for obtaining the abrasive, and the abrasive is obtained by diluting with water (for example, diluting it to 1.5 times or more on a mass basis). In this embodiment, the abrasive may be prepared by diluting the stock solution with water immediately before polishing. Alternatively, a stock solution and water may be supplied onto the polishing platen to prepare an abrasive on the polishing platen.

<Polishing method>
Next, the polishing method (substrate polishing method) according to the present embodiment will be described.

  The polishing method according to the present embodiment includes a polishing step of polishing a surface to be polished using the abrasive according to the present embodiment. The abrasive may be an abrasive obtained by diluting an abrasive stock solution with water. The surface to be polished may contain a tungsten material, and may have at least a layer containing a tungsten material. In the polishing step, for example, a surface to be polished of the substrate is pressed against a polishing cloth of a polishing platen, and a predetermined pressure is applied to the substrate from a surface of the substrate opposite to the surface to be polished (back surface of the substrate). This is a step of polishing the surface to be polished by supplying the abrasive according to the present embodiment between the surface to be polished of the substrate and the polishing cloth and moving the substrate relative to the polishing platen. In the polishing step, a material to be polished including a tungsten material can be polished. The material to be polished may be a film (a film to be polished) or a tungsten material film.

  The polishing step is a step of polishing the surface to be polished including the tungsten material and at least one selected from the group consisting of a barrier material (for example, a barrier metal) and an insulating material using the polishing agent according to the present embodiment. There may be. The polishing step may be, for example, a step of polishing a substrate having at least a layer containing a tungsten material and at least one selected from the group consisting of a barrier layer and an insulating layer. Examples of the barrier material include tantalum, a tantalum alloy, a tantalum compound (such as tantalum oxide and tantalum nitride), titanium, a titanium alloy, and a titanium compound (such as titanium oxide and titanium nitride). Examples of the insulating material include silicon oxide and silicon nitride.

As the polishing apparatus, for example, a general polishing apparatus having a motor or the like capable of changing the number of rotations attached thereto and having a polishing platen to which a polishing cloth can be attached and a holder for holding a substrate can be used. Although there is no particular limitation on the polishing cloth, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used. The polishing conditions are not particularly limited, but it is preferable to adjust the rotation speed of the polishing table to a low rotation of 200 min ⁻¹ (rpm) or less so that the substrate does not pop out. During polishing, the polishing agent can be continuously supplied to the polishing cloth by a pump or the like. Although there is no limitation on the supply amount, it is preferable that the surface of the polishing pad is always covered with the abrasive, and that the formed product due to the progress of polishing is continuously discharged.

  In order to carry out polishing (CMP) while keeping the surface condition of the polishing cloth always the same, it is preferable to carry out a conditioning step of the polishing cloth before polishing. For example, using a dresser with diamond particles, conditioning of the polishing pad is performed with a liquid containing at least water. Subsequently, after the polishing method according to the present embodiment is performed, it is preferable to further perform a substrate cleaning step. After the polishing is completed, the substrate is preferably washed well in running water, and then dried by spin-drying or the like to remove water droplets attached to the substrate. In addition, a known cleaning method (for example, a method in which a brush made of polyurethane is rotated while a commercially available cleaning liquid is applied to the surface of the substrate, and the brush is pressed against the substrate at a constant pressure to remove deposits on the substrate) is used. It is more preferred to dry after implementation.

  The polishing rate of the tungsten material is preferably 20 nm / min or more, more preferably 25 nm / min or more, and still more preferably 30 nm / min or more, from the viewpoint of shortening the polishing time. The polishing rate of the tungsten material is preferably 50 nm / min or less from the viewpoint that the insulating material is sufficiently polished and the erosion amount is easily reduced. From these viewpoints, the polishing rate of the tungsten material is preferably 20 to 50 nm / min, more preferably 25 to 50 nm / min, and still more preferably 30 to 50 nm / min.

  The polishing rate of the insulating material is preferably 80 nm / min or more, more preferably 85 nm / min or more, and further preferably 90 nm / min or more, from the viewpoint of shortening the polishing time. The polishing rate of the insulating material is preferably 110 nm / min or less, from the viewpoint of easily suppressing excessive polishing of the insulating material, easily reducing the erosion amount, and easily improving the flatness. From these viewpoints, the polishing rate of the insulating material is preferably from 80 to 110 nm / min, more preferably from 85 to 110 nm / min, and still more preferably from 90 to 110 nm / min.

  The erosion amount is preferably 15 nm or less, more preferably 13 nm or less, and still more preferably 10 nm or less, from the viewpoint of easily suppressing problems such as an increase in wiring resistance.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, malic acid was used for the adjustment of the pH of the abrasive as needed.

<Preparation of abrasive>
(Example 1)
In a container, 0.30 parts by mass of dextrin 1 having a weight average molecular weight of 100,000 as a polysaccharide and an acrylic acid / methacrylic acid block copolymer (AA / MA copolymer, copolymerization ratio as a (meth) acrylic acid-based polymer) : 1/99, Mw: 7000) 0.05 part by mass. Subsequently, 94.65 parts by mass of ultrapure water was poured into the container and stirred to dissolve each component. Next, silica particles having an average particle diameter of 70 nm corresponding to 2.00 parts by mass were added. Finally, 3.00 parts by mass of hydrogen peroxide was added to obtain an abrasive.

(Example 2)
An abrasive was obtained in the same manner as in Example 1 except that dextrin 2 having a weight average molecular weight of 17000 was used instead of dextrin 1 as a polysaccharide.

(Example 3)
An abrasive was obtained in the same manner as in Example 1 except that dextran 1 having a weight average molecular weight of 40,000 was used instead of dextrin 1 as a polysaccharide.

(Example 4)
An abrasive was obtained in the same manner as in Example 1 except that dextran 2 having a weight average molecular weight of 200000 was used instead of dextrin 1 as a polysaccharide.

(Example 5)
An abrasive was obtained in the same manner as in Example 1, except that the content of dextrin 1 was changed from 0.30 parts by mass to 0.10 parts by mass.

(Example 6)
An abrasive was obtained in the same manner as in Example 1, except that the content of dextrin 1 was changed from 0.30 parts by mass to 1.00 parts by mass.

(Comparative Example 1)
An abrasive was obtained in the same manner as in Example 1 except that dextrin 1 was not used.

(Comparative Example 2)
An abrasive was obtained in the same manner as in Example 1, except that the content of dextrin 1 was changed from 0.30 parts by mass to 2.50 parts by mass.

(Comparative Example 3)
An abrasive was obtained in the same manner as in Example 1, except that the content of dextrin 1 was changed from 0.30 part by mass to 0.05 part by mass.

(Comparative Example 4)
An abrasive was obtained in the same manner as in Example 1 except that no abrasive grains were used.

(Comparative Example 5)
An abrasive was obtained in the same manner as in Example 1 except that hydrogen peroxide was not used.

(Comparative Example 6)
An abrasive was obtained in the same manner as in Example 1 except that dextrin 3 having a weight average molecular weight of 4000 was used instead of dextrin 1.

(Comparative Example 7)
An abrasive was obtained in the same manner as in Example 1 except that dextrin 4 having a weight average molecular weight of 300,000 was used instead of dextrin 1.

(Comparative Example 8)
An abrasive was obtained in the same manner as in Example 1 except that glucose, a monosaccharide, was added instead of dextrin 1.

<PH measurement>
The pH of the abrasive was measured under the following measurement conditions.
[PH measurement conditions]
Measuring instrument: Horiba Ltd., Product name: Model (F-51)
Calibration solution: Phthalate pH standard solution (4.01), neutral phosphate pH standard solution (pH 6.86) and borate pH standard solution (pH 9.18)
Measurement temperature: 25 ° C
Measuring procedure: After three-point calibration using a calibration solution, the electrode was placed in a measurement object and allowed to stand at 25 ° C. for 2 minutes or more, and the pH at the time of stabilization was measured.

<Evaluation>
As the evaluation substrates in Examples 1 to 6 and Comparative Examples 1 to 8, a blanket substrate having a tungsten film, a blanket substrate having a silicon oxide film, and a pattern substrate with tungsten wiring (754 CMP pattern made by SEMATECH) were used. . In addition, a pattern substrate with copper wiring (854 CMP pattern manufactured by SEMATECH) was used as the evaluation substrate of Example 1. These substrates were polished using the abrasive prepared above. In the polishing of the pattern substrate, finish polishing was performed after rough polishing of the pattern substrate.

  As shown in FIG. 2A, the pattern substrate with tungsten wiring before rough polishing had a stripe-shaped pattern portion (a portion in which a wiring metal portion and an insulating film portion were alternately arranged). The pattern substrate includes a silicon oxide film 11 having an uneven surface, a barrier film 12 formed to follow the unevenness of the surface of the silicon oxide film 11, and a tungsten film 13 deposited to fill the unevenness. Had. The barrier film 12 of the pattern substrate was a titanium nitride film (titanium nitride film) having a thickness of 30 nm. Prior to the final polishing using the abrasive prepared above, the tungsten film is roughly polished by a CMP method using a known abrasive in which the polishing rate of the tungsten film is much higher than that of the silicon oxide film, and then washed. As shown in b), the silicon oxide film of the projection was exposed on the surface to be polished.

  As a polishing and cleaning device, a CMP polishing machine Reflexion LK (manufactured by APPLIED MATERIALS) was used. As the polishing cloth, a polishing cloth made of a foamed polyurethane resin (trade name: IC1010, manufactured by Rohm and Haas) was used. The rotation speed of the platen was 93 times / min, the rotation speed of the head was 87 times / min, the polishing pressure was 21 kPa, and the supply amount of the abrasive was adjusted to 300 mL / min. The polishing time for the blanket substrate and the patterned substrate was 60 seconds.

(Evaluation of blanket substrate)
The polishing rate of the tungsten film was determined using a blanket substrate having a tungsten film. The thickness of the tungsten film before and after polishing was measured using a metal film thickness measuring device (model number VR-120 / 08S, manufactured by Hitachi Kokusai Electric Inc.), and the polishing rate was determined from the difference in film thickness.

  The polishing rate of the silicon oxide film was determined using a blanket substrate having the silicon oxide film. The thickness of the silicon oxide film before and after polishing was measured using a film thickness measuring device RE-3000 (manufactured by Dainippon Screen Mfg. Co., Ltd.), and the polishing rate was determined from the difference in film thickness.

(Evaluation of pattern substrate)
[Pattern substrate with tungsten wiring]
The erosion amount after the rough polishing is, as shown in FIG. 2B, the film thickness A1 of the silicon oxide film portion at the outer edge of the substrate and the stripe pattern portion in the pattern substrate obtained by the above rough polishing and cleaning. (A1-B1) from the thickness B1 of the silicon oxide film of FIG.

  The erosion amount after the final polishing is, as shown in FIG. 2C, the difference between the thickness A2 of the silicon oxide film at the outer edge of the substrate and the thickness B2 of the silicon oxide film at the stripe pattern portion ( A2-B2).

  The polishing amount of the silicon oxide film at the outer edge of the substrate was obtained by subtracting the film thickness A2 after the finish polishing from the film thickness A1 after the rough polishing (A1-A2). The polishing amount of the silicon oxide film in the stripe pattern portion was obtained by subtracting the film thickness B2 after the finish polishing from the film thickness B1 after the rough polishing (B1-B2).

  The film thickness of the silicon oxide film was measured using an optical interference film thickness meter (manufactured by Nanometrics, model No. NanoSpec / AFT5100).

  The erosion improvement amount was obtained as a difference ((A1-B1)-(A2-B2)) between the erosion amount after rough polishing (A1-B1) and the erosion amount after finish polishing (A2-B2).

[Pattern board with copper wiring]
The erosion amount and the erosion improvement amount were calculated from the difference in the thickness of the silicon oxide film before and after polishing as in the case of the pattern substrate with tungsten wiring.

  Table 1 shows the results of the examples, and Table 2 shows the results of the comparative examples. The content of each component in Tables 1 and 2 is a content based on the total mass of the abrasive.

As shown in Table 1, in Examples 1 to 6, when the patterned substrate with the tungsten wiring was used, the erosion amount after the finish polishing was reduced to 10 nm or less.
The erosion amount after the finish polishing in Example 1 is smaller than that of the comparative example, and the polishing amount of the silicon oxide film at the outer edge portion in Example 1 is larger than that of the pattern portion. This is presumably because when dextrin 1 was used as the polysaccharide, the dextrin 1 was adsorbed on the entire surface of the pattern portion to protect the pattern portion, and the silicon oxide film at the outer edge portion was preferentially polished.
When dextrin 2 was used as the polysaccharide (Example 2), the amount of erosion after finish polishing was larger than that in Example 1. This is probably because the use of dextrin 1 having a large weight average molecular weight in Example 1 strengthened the protective effect of the pattern portion.
When dextran 1 was used as the polysaccharide (Example 3), the erosion amount after the finish polishing was larger than that of Example 1, but the erosion amount was smaller than that of Comparative Example.
When dextran 2 was used as the polysaccharide (Example 4), the amount of erosion after finish polishing was smaller than in Example 3. This is presumably because the use of dextran 2 having a large weight average molecular weight in Example 4 strengthened the protective effect of the pattern portion.
When the amount of dextrin 1 was reduced (Example 5), the amount of erosion after finish polishing was larger than that of Example 1.
When the amount of dextrin 1 was increased (Example 6), the erosion amount after the finish polishing was smaller than that in Example 1. This is considered to be because the effect of protecting the pattern portion was enhanced by increasing the amount of dextrin 1 in Example 6.
When the pattern substrate with copper wiring is used instead of the pattern substrate with tungsten wiring (Example 1), the erosion amount after the final polishing is larger than the erosion amount after the rough polishing. This is presumably because no protective film of dextrin 1 was formed on the copper wiring pattern portion.

As shown in Table 2, in Comparative Examples 1, 6, and 8 using an abrasive containing no polysaccharide having the structural unit represented by the formula (I), the erosion amount after the finish polishing was measured in Examples 1 to 6. The polishing amount of the silicon oxide film at the outer edge is smaller than that of the pattern portion. This is probably because the polysaccharide has no protective action on the pattern portion.
When dextrin 1 is excessively increased (Comparative Example 2), the erosion amount after the finish polishing is a negative value. This is because the protective effect of the dextrin 1 on the pattern portion is too strong, the tungsten film is hardly polished, the silicon oxide film on the outer edge portion is polished more excessively than the pattern portion, and the pattern portion is a silicon oxide film on the outer edge portion. It is considered that a phenomenon (hereinafter, referred to as “protrusion”) that has become more exciting has occurred.
When dextrin 1 is excessively reduced (Comparative Example 3), the erosion amount after the finish polishing is larger than that after the rough polishing. This is presumably because the amount of the polysaccharide used was small, and the protective effect of the pattern portion was insufficient.
When the abrasive grains were not used (Comparative Example 4), the polishing rates of the tungsten film and the silicon oxide film were very low, and the erosion amount after the finish polishing was almost equal to the erosion amount after the rough polishing.
When the oxidizing agent was not used (Comparative Example 5), the erosion amount after the finish polishing was a negative value. This is because the tungsten film is hardly polished due to the lack of the chemical action due to the absence of the oxidizing agent and the protective action of the pattern portion by the dextrin 1, and the silicon oxide film at the outer edge is excessively larger than the pattern portion. It is considered that polishing was performed and protolution occurred.
When dextrin 3 having a weight average molecular weight of 4000 was used (Comparative Example 6), the erosion amount after the final polishing was larger than that after the rough polishing. This is presumably because the weight-average molecular weight of the polysaccharide was small, and the protective effect of the pattern portion was insufficient.
When dextrin 4 having a weight average molecular weight of 300,000 was used (Comparative Example 7), the erosion amount after the finish polishing was a negative value. This is probably because the protective effect of the dextrin 4 on the pattern portion was too strong, so that the tungsten film was hardly polished, and the silicon oxide film on the outer edge portion was polished more excessively than the pattern portion, thereby causing prototrusion. .
When the monosaccharide glucose was used (Comparative Example 8), the erosion amount after the final polishing was larger than that after the rough polishing. This is presumably because the protective effect of glucose on the pattern portion was insufficient.

DESCRIPTION OF SYMBOLS 1 ... Insulating film, 2 ... Barrier layer, 3 ... Wiring metal, 11 ... Silicon oxide film, 12 ... Barrier film, 13 ... Tungsten film.

Claims (9)

An abrasive, an oxidizing agent, at least one polysaccharide selected from the group consisting of dextrin and dextran, and a (meth) acrylic acid-based polymer,
The polysaccharide has a weight average molecular weight of 100,000 to 250,000,
An abrasive for tungsten, wherein the content of the polysaccharide is 0.1 to 2.0% by mass based on the total mass of the abrasive . The abrasive comprises silica abrasive according to claim 1. The abrasive according to claim 2 , wherein the silica is colloidal silica. The abrasive according to any one of claims 1 to 3 , wherein the pH is 2.0 to 6.0. The (meth) acrylic acid-based polymer is obtained by polymerizing a homopolymer of acrylic acid, a homopolymer of methacrylic acid, and a composition containing acrylic acid and methacrylic acid as monomer components. The abrasive according to any one of claims 1 to 4 , wherein the abrasive is at least one selected from the group consisting of coalescence. The polishing agent according to any one of claims 1 to 5 , which is used for polishing a surface to be polished including a tungsten material and at least one selected from the group consisting of a barrier material and an insulating material. An abrasive storage solution for obtaining the abrasive according to any one of claims 1 to 6 ,
A stock solution for an abrasive, wherein the abrasive is obtained by dilution with water. A polishing method comprising a step of polishing a surface to be polished using the polishing slurry according to any one of claims 1 to 6 or a polishing slurry obtained from the stock solution for polishing slurry according to claim 7 . The polishing method according to claim 8 , wherein the polished surface includes a tungsten material.

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