JP2013098392A - Polishing composition and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition suitable for polishing of a substrate including general metal wiring materials.SOLUTION: The polishing composition includes abrasive grains (a), a complexing agent (b), and a metal anticorrosive (c). The abrasive grains (a) have a plurality of projections on surfaces thereof, and an average of values obtained by dividing heights of projections on surfaces of grains having grain sizes larger than a volume average grain size of the abrasive grains, out of the abrasive grains, by widths in base parts of the projections is 0.245 or more. Further, it is preferable that an average height of projections on surfaces of grains having grain sizes larger than the volume average grain size of the abrasive grains, out of the abrasive grains, is 2.5 nm or more.

Description

  The present invention relates to a polishing composition for a substrate surface (hereinafter referred to as “polishing object”) containing a metal in, for example, a semiconductor integrated circuit (hereinafter referred to as “LSI”).

Along with higher integration and higher speed of LSI, new fine processing technology has been developed. Chemical mechanical polishing (hereinafter referred to as “CMP”) is one of them, and planarization of an interlayer insulating film, formation of contact plugs, embedded wiring in an LSI manufacturing process, particularly a multilayer wiring forming process. Has been applied to the formation of. This technique is disclosed in Patent Document 1, for example.

In the formation of the embedded wiring, aluminum (Al), tungsten (W), copper (Cu), or an alloy thereof is used as a conductive substance that becomes a wiring material. And the polishing composition for metals used when grind | polishing the board | substrate surface containing such a metal wiring material typically contains a complexing agent and an oxidizing agent, and also abrasive grains as needed. It is effectively polished using etching. It is also considered effective to use a polishing composition further added with a metal anticorrosive to improve the smoothness of the polished object after polishing. For example, Patent Document 2 discloses the use of a polishing composition containing aminoacetic acid and / or amidosulfuric acid, an oxidizing agent, benzotriazole, and water.

However, the composition of typical polishing compositions used for polishing a substrate surface containing a metal wiring material, in particular, various studies on the types, contents and combinations of the above complexing agents, oxidizing agents and metal anticorrosives However, there is no universal combination that can be used under all conditions. If the ratios and combinations of the contents of the complexing agent, the oxidizing agent, and the metal anticorrosive are shifted, there is a problem that the generation of scratch defects and the flatness are impaired.

JP-A-62-102543 JP-A-8-83780

  Therefore, an object of the present invention is to provide a polishing composition that can be suitably used for polishing a substrate containing a general metal wiring material. In particular, in an environment where a typical polishing composition for polishing a substrate containing a conventional metal wiring material is diluted on the substrate by cleaning or the like, the polishing composition (particularly the complexing agent) is diluted. Nevertheless, the metal wiring material was etched, and a new problem was found that the smoothness of the surface of the metal wiring material was impaired. The objective of this invention is providing the polishing composition which solved the said new subject.

As a result of intensive studies, the present inventors have found a polishing composition that improves the smoothness of the surface of a metal wiring material and the like by including specific abrasive grains.

That is, the gist of the present invention is as follows.
<1> A polishing composition comprising (a) abrasive grains, (b) a complexing agent, and (c) a metal anticorrosive,
(A) Abrasive grains have a plurality of protrusions on the surface, and the protrusions each having a particle having a particle diameter larger than the volume average particle diameter of the abrasive grains on the surface have the same protrusion height. A polishing composition characterized in that the average value obtained by dividing by the width at the base of is no less than 0.245.
<2> Of the abrasive grains, the average height of protrusions on the surface of particles having a particle diameter larger than the volume average particle diameter of the abrasive grains is 2.5 nm or more.
<3> The abrasive is colloidal silica.
<4> Colloidal silica having an average secondary particle diameter of 30 to 100 nm.
<5> Polishing composition is used for the use which grind | polishes the board | substrate containing a metal.
<6> The metal contains copper.
<7> A polishing method for polishing a metal using the polishing composition according to any one of <1> to <6>.
<8> A method for producing a metal-containing substrate, comprising the step of using the polishing method according to <7>.

ADVANTAGE OF THE INVENTION According to this invention, the polishing composition which can be used suitably for the use which grind | polishes the board | substrate containing a general metal wiring material is provided. In particular, a polishing composition effective for improving the smoothness of the metal wiring material surface and the like is provided.

The figure which shows the outline which projected the external shape of the abrasive grain contained in the polishing composition which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described.
The polishing composition of the present embodiment is used for polishing for producing an LSI as described above in the Background Art section, and is preferably used mainly in a metal polishing step. Therefore, this polishing composition is used in polishing applications for forming wirings, contact holes, and via holes in which metals are used in LSI manufacturing. Examples of the metal at that time include copper, tungsten, tantalum, titanium, cobalt, ruthenium, and oxides, alloys and compounds thereof. Among these, copper, tantalum, titanium, ruthenium and oxides, alloys and compounds thereof are preferable, and copper and oxides, alloys and compounds thereof are more preferable.

  The polishing composition of the present embodiment contains specific abrasive grains and is further prepared by optionally mixing with other additives in a solvent such as water. The polishing composition of this embodiment provides a polishing composition that is effective for improving the smoothness of the surface of the metal wiring material on the object to be polished. The smoothness refers to the flatness and smoothness of the substrate surface that is the object to be polished after polishing, and is represented by, for example, surface roughness (Ra), root mean square roughness (RMS), or the like. In the use of a typical polishing composition for polishing a substrate containing a conventional metal wiring material, the cause of the loss of smoothness is excessive oxidation of the object to be polished by an oxidizing agent, complexing agent. Excessive etching on the polishing object due to the above, and the effect of the metal anticorrosive agent on the polishing object is low. The environment in which the phenomenon that causes the smoothness to be impaired occurs is the composition accompanying the diversion to the polishing process under different conditions of the polishing composition, the mismatch of each content and combination, and before and after the polishing process. Deviations in the optimum range of the composition and content associated with dilution of the polishing composition in the cleaning step and the like are conceivable. In particular, the inventors dilute the polishing composition in an environment where a typical polishing composition for polishing a substrate containing a conventional metal wiring material is diluted on the substrate by cleaning or the like. Nevertheless, the metal wiring material was etched, and a new problem was found that the smoothness of the surface of the metal wiring material was impaired.

  This decrease in smoothness on the surface of the metal wiring material is a defect that occurs irregularly and locally on the substrate surface (particularly the surface of the metal wiring material), unlike the conventional problems such as dishing and erosion. Details of the mechanism are unknown, but it is probably one of the following three.

(1) The etching action of the complexing agent is strong, and the concentration of the metal anticorrosive decreases with dilution of the polishing composition, the metal anticorrosive effect decreases, and the smoothness decreases.
(2) The polishing composition is non-uniformly diluted, and the etching action of the complexing agent exceeds the effect of the metal anticorrosive agent depending on the site, so that the smoothness is lowered.
(3) With the dilution of the polishing composition, the abrasive concentration in the polishing composition decreases, the mechanical removal effect on the surface of the polishing object decreases, and the smoothness decreases.

(Abrasive grains)
The polishing composition of this embodiment contains specific abrasive grains. The specific abrasive grain of the present invention specifically refers to an abrasive grain containing abrasive grains having a plurality of protrusions on the surface. Although the details of the mechanism that can suppress the above-described decrease in smoothness by using this specific abrasive grain are not certain, the mechanical removal effect on the surface of the object to be polished is probably due to the abrasive grains having multiple protrusions on the surface. It is presumed that it increases. And it is estimated that the effect is maintained as compared with abrasive grains that do not have a plurality of protrusions on the surface even in an environment where the polishing composition containing abrasive grains is diluted by washing or the like.

  The usable abrasive grains may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of metal oxides such as silica, alumina, ceria, titania, and silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. Among these, silica particles are preferable, and colloidal silica is particularly preferable.

  The abrasive grains may be surface-modified. Since ordinary colloidal silica has a zeta potential value close to zero under acidic conditions, silica particles are not electrically repelled with each other under acidic conditions and are likely to agglomerate. On the other hand, abrasive grains whose surfaces are modified so that the zeta potential has a relatively large negative value even under acidic conditions are strongly repelled from each other and dispersed well even under acidic conditions, resulting in storage of the polishing composition. Stability will be improved. Such surface-modified abrasive grains can be obtained, for example, by mixing a metal such as aluminum, titanium or zirconium or an oxide thereof with the abrasive grains and doping the surface of the abrasive grains.

  The number of the protrusions on the surface of the abrasive grains in the polishing composition is preferably 3 or more on an average per abrasive grain, and more preferably 5 or more.

  The protrusions herein have a height and width that are sufficiently smaller than the particle diameter of the abrasive grains. Furthermore, in FIG. 1, the length of the portion shown as the curve AB passing through the points A and B is the circumferential length of the largest inscribed circle of the abrasive grains, more precisely, the abrasive grains. The projections do not exceed a quarter of the circumference of the largest circle inscribed in the contour projected from the contour. Note that the width of the protrusion refers to the width at the base of the protrusion, and is represented as the distance between the point A and the point B in FIG. Further, the height of the protrusion refers to the distance between the base of the protrusion and the portion of the protrusion farthest from the base, and is represented as the length of the line segment CD orthogonal to the straight line AB in FIG. Is.

  It is obtained by dividing the height of the projections on the surface of the abrasive grains in the polishing composition having a particle diameter larger than the volume average particle diameter of the abrasive grains by the width at the base of the same projection. The average value is essential to be 0.245 or more, preferably 0.255 or more. When the average of these values is 0.245 or more, the mechanical polishing power of the abrasive grains is improved because the shape of the protrusion is relatively sharp. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. Moreover, when the average of this value is 0.255 or more, the mechanical polishing power of the abrasive grains is improved. The height of each protrusion of the abrasive grains and the width at the base thereof can be obtained by analyzing the image of the abrasive grains with a scanning electron microscope using general image analysis software.

  Of the abrasive grains in the polishing composition, the average height of protrusions on the surface of particles having a particle diameter larger than the volume average particle diameter of the abrasive grains is preferably 2.5 nm or more, more preferably Is 2.7 nm or more, more preferably 3.0 nm or more. In this case, the mechanical polishing power of the abrasive grains contained in the polishing composition is improved. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. Note that the average height of the projections of the abrasive grains can also be obtained using general image analysis software.

  Of the abrasive grains in the polishing composition, the average aspect ratio of particles having a particle diameter larger than the volume average particle diameter of the abrasive grains is preferably 1.0 or more, and more preferably 1.05 or more. In this case, the mechanical polishing power of the abrasive grains contained in the polishing composition is improved. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. The average aspect ratio of the abrasive grains is a value obtained by dividing the length of the longest side of the smallest rectangle circumscribing the image of the abrasive grains by a scanning electron microscope by the length of the short side of the same rectangle. Average and can be determined using common image analysis software.

  The lower limit of the abrasive content is preferably 0.001% by mass, more preferably 0.005% by mass, and still more preferably 0.01% by mass. As the abrasive content increases, the mechanical polishing power of the abrasive improves. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. Moreover, it is preferable that the upper limit of content of an abrasive grain is 20 mass%, More preferably, it is 15 mass%, More preferably, it is 10 mass%. As the content of the abrasive grains decreases, the material cost of the polishing composition can be reduced, and in addition, aggregation of the abrasive grains hardly occurs. Moreover, it is easy to obtain a polished surface with few surface defects.

  The lower limit of the average primary particle diameter of the abrasive grains is preferably 10 nm, more preferably 15 nm, and still more preferably 20 nm. As the average primary particle diameter of the abrasive grains increases, the mechanical polishing power of the abrasive grains improves. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. Moreover, it is preferable that the upper limit of the average primary particle diameter of an abrasive grain is 80 nm, More preferably, it is 70 nm, More preferably, it is 60 nm. As the average primary particle diameter of the abrasive grains decreases, it is easy to obtain a polished surface with few surface defects. In addition, the value of the average primary particle diameter of an abrasive grain can be calculated based on the specific surface area of the abrasive grain measured by BET method, for example.

  The lower limit of the average secondary particle diameter of the abrasive grains is preferably 10 nm, more preferably 20 nm, still more preferably 30 nm. As the average secondary particle diameter of the abrasive grains increases, the mechanical polishing power of the abrasive grains improves. As a result, the effect of repairing the substrate surface with reduced smoothness caused by dilution of the polishing composition is enhanced. The upper limit of the average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 100 nm, for example, more preferably 90 nm, and still more preferably 80 nm. As the average secondary particle diameter of the abrasive grains decreases, it is easy to obtain a polished surface with few surface defects. In addition, the value of the average secondary particle diameter of an abrasive grain can be measured by the laser light scattering method, for example.

(Oxidant)
The polishing composition may further contain an oxidizing agent in addition to the specific abrasive grains, complexing agent and metal anticorrosive described above. The oxidizing agent has an action of oxidizing the surface of the object to be polished, and when an oxidizing agent is added to the polishing composition, there is an effect of improving the polishing rate by the polishing composition.

  An oxidizing agent that can be used is, for example, a peroxide. Specific examples of the peroxide include, for example, hydrogen peroxide, peracetic acid, percarbonate, urea peroxide and perchloric acid, and persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate. Among them, persulfate and hydrogen peroxide are preferable from the viewpoint of polishing rate, and hydrogen peroxide is particularly preferable from the viewpoint of stability in an aqueous solution and environmental load.

  The content of the oxidizing agent in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. As the content of the oxidizing agent increases, the polishing rate can be improved.

  The content of the oxidizing agent in the polishing composition is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. As the content of the oxidizing agent decreases, the material cost of the polishing composition can be reduced, and the load on the processing of the polishing composition after polishing, that is, the waste liquid treatment can be reduced. In addition, since the surface of the object to be polished is not easily oxidized by the oxidizing agent, the smoothness of the object to be polished after polishing is improved.

(Complexing agent)
The polishing composition contains a complexing agent. The complexing agent contained in the polishing composition has an action of chemically etching the surface of the object to be polished, and functions to improve the polishing rate by the polishing composition.

  The content of the complexing agent in the polishing composition is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.1% by mass or more. As the content of the complexing agent increases, the etching effect on the surface of the polishing object increases. As a result, the polishing rate by the polishing composition is improved.

  The complexing agent content in the polishing composition is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 10% by mass or less. As the content of the complexing agent decreases, excessive etching of the surface of the object to be polished by the complexing agent is less likely to occur. As a result, the smoothness of the polished object after polishing is improved.

  Complexing agents that can be used are, for example, inorganic acids, organic acids, and amino acids. Specific examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid. Specific examples of the organic acid include, for example, 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 lactic acid. Organic sulfuric acids such as methanesulfonic acid, ethanesulfonic acid and isethionic acid can also be used. A salt such as an ammonium salt or an alkali metal salt of an inorganic acid or an organic acid may be used instead of or in combination with the inorganic acid or the organic acid. Specific examples of amino acids include, for example, glycine, α-alanine, β-alanine, N-methylglycine, N, N-dimethylglycine, 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, phenylalanine, proline, Sarcosine, ornithine, lysine, taurine, serine, threonine, homoserine, tyrosine, bicine, tricine, 3,5-diiodo-tyrosine, β- (3,4-dihydroxyphenyl) -alanine, thyroxine, 4-hydroxy-proline, cysteine , Methionine, ethionine, lanthionine, cystathionine, cystine, cysteic acid, aspartic acid, glutamic acid, S- (carboxymethyl) -cysteine, 4-aminobutyric acid, asparagine, glutamine, azaserine, arginine, canavani , Citrulline, .delta.-hydroxy - lysine, creatine, histidine, 1-methyl - histidine, 3-methyl - include histidine and tryptophan. Among them, as a complexing agent, glycine, alanine, malic acid, tartaric acid, citric acid, glycolic acid, isethionic acid, or an ammonium salt or alkali metal salt thereof is preferable from the viewpoint of improving polishing.

(Metal anticorrosive)
The polishing composition contains a metal anticorrosive. When a metal anticorrosive is added to the polishing composition, there is an effect that surface defects such as dishing are less likely to occur on the surface of the object to be polished after polishing with the polishing composition. In addition, when the polishing composition contains an oxidizing agent and / or a complexing agent, the metal anticorrosive agent reduces oxidation of the surface of the object to be polished by the oxidizing agent and polishes by the oxidizing agent. It reacts with metal ions generated by oxidation of the metal on the surface of the object to generate an insoluble complex. As a result, etching on the surface of the object to be polished by the complexing agent can be suppressed, and the smoothness of the object to be polished after polishing is improved.

  Although the kind of metal anticorrosive which can be used is not specifically limited, Preferably it is a heterocyclic compound. The number of heterocyclic rings in the heterocyclic compound is not particularly limited. The heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring.

  Specific examples of the heterocyclic compound as the metal anticorrosive include, for example, a pyrrole compound, a pyrazole compound, an imidazole compound, a triazole compound, a tetrazole compound, a pyridine compound, a pyrazine compound, a pyridazine compound, a pyridine compound, an indolizine compound, an indole compound, Indole compounds, indazole compounds, purine compounds, quinolidine compounds, quinoline compounds, isoquinoline compounds, naphthyridine compounds, phthalazine compounds, quinoxaline compounds, quinazoline compounds, cinnoline compounds, buteridine compounds, thiazole compounds, isothiazole compounds, oxazole compounds, isoxazole compounds and Examples thereof include nitrogen-containing heterocyclic compounds such as furazane compounds. Specific examples of the pyrazole compound include 1H-pyrazole, 4-nitro-3-pyrazole carboxylic acid, and 3,5-pyrazole carboxylic acid. Specific examples of the imidazole compound include, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, and benzimidazole. 5,6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole and 2-methylbenzimidazole. Specific examples of the triazole compound include, for example, 1,2,3-triazole, 1,2,4-triazole, 1-methyl-1,2,4-triazole, methyl-1H-1,2,4-triazole- 3-carboxylate, 1,2,4-triazole-3-carboxylic acid, methyl 1,2,4-triazole-3-carboxylate, 3-amino-1H-1,2,4-triazole, 3-amino- 5-benzyl-4H-1,2,4-triazole, 3-amino-5-methyl-4H-1,2,4-triazole, 3-nitro-1,2,4-triazole, 3-bromo-5 Nitro-1,2,4-triazole, 4- (1,2,4-triazol-1-yl) phenol, 4-amino-1,2,4-triazole, 4-amino-3,5-dipropyl-4H -1, , 4-triazole, 4-amino-3,5-dimethyl-4H-1,2,4-triazole, 4-amino-3,5-dipeptyl-4H-1,2,4-triazole, 5-methyl-1 2,4-triazole-3,4-diamine, 1-hydroxybenzotriazole, 1-aminobenzotriazole, 1-carboxybenzotriazole, 5-chloro-1H-benzotriazole, 5-nitro-1H-benzotriazole, 5 -Carboxy-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, 1- (1 ″, 2′-dicarboxyethyl) benzotriazole. Specific examples of the tetrazole compound include 1H-tetrazole, 5-methyltetrazole, 5-aminotetrazole, and 5-phenyltetrazole. Specific examples of indole compounds include 1H-indole, 1-methyl-1H-indole, 2-methyl-1H-indole, 3-methyl-1H-indole, 4-methyl-1H-indole, 5-methyl- 1H-indole, 6-methyl-1H-indole, and 7-methyl-1H-indole. Specific examples of the indazole compound include 1H-indazole and 5-amino-1H-indazole. The metal anticorrosive is preferably a heterocyclic compound having a triazole skeleton, and among them, 1,2,3-triazole and 1,2,4-triazole are particularly preferable. Since these heterocyclic compounds have a high chemical or physical adsorption force to the surface of the object to be polished, a stronger protective film is formed on the surface of the object to be polished. This can suppress excessive etching of the surface of the object to be polished after polishing with the polishing composition. As a result, excessive polishing can be suppressed.

  The content of the metal anticorrosive in the polishing composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and further preferably 0.01% by mass or more. As the content of the metal anticorrosive increases, excessive etching of the surface of the object to be polished after polishing with the polishing composition can be suppressed. As a result, the smoothness of the polished object after polishing is improved.

  The content of the metal anticorrosive in the polishing composition is also preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less. As the content of the metal anticorrosive decreases, there is an effect that the polishing rate by the polishing composition is improved.

(Polishing composition pH and pH adjuster)
It is preferable that pH of polishing composition is 11 or less, More preferably, it is 10 or less, More preferably, it is 9 or less. As the pH of the polishing composition decreases, the safety of the polishing composition increases and the polishing rate improves. Moreover, it is preferable that pH of polishing composition is 3 or more, More preferably, it is 4 or more, More preferably, it is 5 or more. As the pH of the polishing object increases, etching of the surface of the polishing object by the polishing composition is less likely to occur, and as a result, generation of surface defects can be further suppressed.

  The pH adjuster used as necessary to adjust the pH of the polishing composition to a desired value may be either acid or alkali, and may be any of inorganic and organic compounds. .

(Surfactant)
In addition to the above-mentioned specific abrasive grains, complexing agent and metal anticorrosive agent, the polishing composition may further contain a surfactant. When a surfactant is added to the polishing composition, dents are less likely to be formed on the sides of the wiring formed by polishing using the polishing composition, and polishing is performed using the polishing composition. There is an effect that dishing is less likely to occur on the surface of the polished object after the polishing.

  The type of surfactant that can be used is not particularly limited, and may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. A plurality of types of surfactants may be used in combination, and it is particularly preferable to use a combination of an anionic surfactant and a nonionic surfactant from the viewpoint of dents or dishing on the side of the wiring.

  Specific examples of the anionic surfactant include, for example, polyoxyethylene alkyl sulfate ester, polyoxyethylene alkyl acetate ester, polyoxyethylene alkyl phosphate ester, alkyl sulfate ester, polyoxyethylene alkyl sulfate, alkyl sulfate, alkylbenzene sulfone. Examples include acids, alkyl phosphate esters, polyoxyethylene alkyl phosphate esters, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl ether sulfuric acid, and salts thereof. Since what is disclosed here as a specific example has a high chemical or physical adsorption force to the surface of the object to be polished, a stronger protective film is formed on the surface of the object to be polished. This is effective in improving the flatness of the surface of the object to be polished after polishing with the polishing composition.

  Specific examples of the cationic surfactant include, for example, alkyl trimethyl ammonium salt, alkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt, and alkyl amine salt.

  Specific examples of amphoteric surfactants include alkyl betaines and alkyl amine oxides.

  Specific examples of the nonionic surfactant include sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, and alkylalkanolamide. Since what is disclosed here as a specific example has a high chemical or physical adsorption force to the surface of the object to be polished, a stronger protective film is formed on the surface of the object to be polished. This is effective in improving the flatness of the surface of the object to be polished after polishing with the polishing composition.

  The content of the surfactant in the polishing composition is preferably 0.001 g / L or more, more preferably 0.005 g / L or more, and still more preferably 0.01 g / L or more. As the content of the surfactant increases, there is an effect that the flatness of the surface of the object to be polished after polishing with the polishing composition is improved.

  The content of the surfactant in the polishing composition is preferably 10 g / L or less, more preferably 5 g / L or less, and still more preferably 1 g / L or less. As the surfactant content decreases, the polishing rate of the polishing composition is improved.

(Water-soluble polymer)
The polishing composition can further contain a water-soluble polymer in addition to the above-mentioned specific abrasive, complexing agent and metal anticorrosive. When a water-soluble polymer is added to the polishing composition, the polishing rate by the polishing composition is controlled by adsorbing the water-soluble polymer on the surface of the abrasive grains or the surface of the object to be polished. In addition, the insoluble components generated during polishing can be stabilized in the polishing composition.

  Water-soluble polymers that can be used are not particularly limited. For example, alginic acid, pectic acid, carboxymethylcellulose, polysaccharides such as curdlan and pullulan, polycarboxylic acids and salts thereof, vinyl polymers such as polyvinyl alcohol and polyacrolein, Polyglycerol and polyglycerol ester are mentioned. Of these, carboxymethylcellulose, pullulan, polycarboxylic acid and salts thereof, and polyvinyl alcohol are preferable, and pullulan and polyvinyl alcohol are particularly preferable.

The embodiment may be modified as follows.
-The polishing composition of the said embodiment may further contain well-known additives, such as antiseptic | preservative and a fungicide, as needed. Specific examples of the antiseptic and fungicide include, for example, isothiazoline-based preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, and paraoxybenzoic acid. Examples include acid esters and phenoxyethanol.
The polishing composition of the above embodiment may be a one-component type or a multi-component type including a two-component type.
-The polishing composition of the said embodiment may be prepared by diluting the undiluted | stock solution of polishing composition 10 times or more using diluents, such as water.
-The polishing composition of the said embodiment may be used for uses other than grinding | polishing for forming the wiring of a semiconductor device.

Next, examples and comparative examples of the present invention will be described.
Colloidal silica as abrasive grains, hydrogen peroxide as an oxidizing agent, glycine as a complexing agent, and benzotriazole as a metal anticorrosive agent were mixed with water, and the polishing compositions of Examples 1 and 2 and Comparative Examples 1 to 5 were mixed. Prepared. Details of the abrasive grains in each composition are as shown in Table 1. Hydrogen peroxide as an oxidizing agent is added so that the concentration becomes 1% by mass. Further, glycine as a complexing agent is added so as to be 1% by mass. Benzotriazole as a metal anticorrosive is added so as to be 0.01% by mass.

  The “primary particle diameter (nm) (BET method)” column in the “Abrasive grain” column of Table 1 shows the average primary particle diameter measured by the BET method for the abrasive grains in each polishing composition. The “secondary particle diameter (nm)” column in the “abrasive grain” column of Table 1 shows the average secondary particle diameter measured by a laser scattering method using Microtrac UPA for the abrasive grains in each polishing composition. The “content (mass%)” column in the “abrasive grain” column of Table 1 shows the content of abrasive grains in each polishing composition. The “presence / absence of projections on the surface” column in the “abrasive grain” column of Table 1 indicates the presence / absence of projections on the surface of the abrasive grains in each polishing composition. In the “average grain width (nm)” column of the “abrasive grain” column of Table 1, particles having a particle diameter larger than the volume average particle diameter of the abrasive grains among the abrasive grains in each polishing composition are listed. The result of having measured the average of the width | variety in the base of the protrusion which has on the surface is shown. In the “Abrasive grain” column of Table 1, the “average height of projections (nm)” column is a particle having a particle diameter larger than the volume average particle diameter of the abrasive grains among the abrasive grains in each polishing composition. The result of having measured the average of the height of the processus | protrusion which the surface has is shown. In the "Abrasive grain" column of Table 1, the "projection height / protrusion width average" column contains particles having a particle diameter larger than the volume average particle diameter of the abrasive grains among the abrasive grains in each polishing composition. The result of having measured the average of the value obtained by dividing | segmenting the height of the processus | protrusion which each has on the surface by the width | variety in the base of the same processus | protrusion is shown.

  Using the polishing compositions of Examples 1 and 2 and Comparative Examples 1 to 5, after polishing a patterned wafer containing a copper wiring metal for a certain period of time, cleaning the substrate surface with ultrapure water on the same platen Table 1 shows the result of evaluation by measuring the Ra value of the copper surface on the substrate surface in the “Ra” column of the “Evaluation” column of Table 1. The polishing conditions are as shown in Table 2, and the Ra measurement conditions are as shown in Table 3.

As shown in Table 1, when the polishing compositions of Examples 1 and 2 were used, the surface roughness was reduced as compared with the polishing compositions of Comparative Examples 1 to 5 that did not satisfy the conditions of the present invention. It was confirmed that the method had a remarkably excellent effect. In this example and the comparative example, it is considered that the slurry remaining on the polishing pad is diluted 75 times or more with ultrapure water by the cleaning after polishing. Although it is not clear why the polishing composition of the present invention has a remarkably excellent effect in suppressing smoothness deterioration in an environment where the polishing composition is diluted by washing or the like in this way, it is not clear that specific conditions are satisfied. It is presumed that the mechanical removal effect on the surface of the object to be polished is increased by using abrasive grains having a plurality of filling projections on the surface. And it is estimated that the effect is maintained as compared with abrasive grains that do not have a plurality of protrusions on the surface even in an environment in which a polishing composition containing abrasive grains is diluted by cleaning or the like.

Claims (8)

A polishing composition comprising (a) abrasive grains, (b) a complexing agent, and (c) a metal anticorrosive,
(A) Abrasive grains have a plurality of protrusions on the surface, and the protrusions each having a particle having a particle diameter larger than the volume average particle diameter of the abrasive grains on the surface have the same protrusion height. A polishing composition characterized in that the average value obtained by dividing by the width at the base of is no less than 0.245.   The polishing composition according to claim 1, wherein the average height of protrusions on the surface of particles having a particle diameter larger than the volume average particle diameter of the abrasive grains is 2.5 nm or more.   The polishing composition according to claim 1, wherein the abrasive grains are colloidal silica.   Polishing composition as described in any one of Claims 1-3 whose average secondary particle diameter of the said abrasive grain is colloidal silica of 30 nm-100 nm.   The polishing composition according to any one of claims 1 to 4, wherein the polishing composition is used in an application for polishing a substrate containing a metal.   The polishing composition according to claim 5, wherein the metal contains copper.   The grinding | polishing method which grind | polishes a metal using the polishing composition as described in any one of Claims 1-6. The manufacturing method of the board | substrate containing a metal which has the process of using the grinding | polishing method of Claim 7.

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