JP6557243B2 - Polishing composition - Google Patents

Description

  The present invention relates to a polishing composition used in a semiconductor device manufacturing process and a polishing method using the same.

  In recent years, a new fine processing technology has been developed along with the high integration and high performance of LSI (Large Scale Integration). The chemical mechanical polishing (CMP) method is one of them, and is frequently used in the LSI manufacturing process, particularly in the flattening of the interlayer insulating film, the formation of the metal plug, and the embedded wiring (damascene wiring) in the multilayer wiring forming process. Technology. This technique is disclosed in Patent Document 1, for example.

  In recent years, CMP has been applied to each process in semiconductor manufacturing, and one aspect thereof is, for example, application to a gate formation process in transistor fabrication. When a transistor is manufactured, a Si-containing material such as silicon, polycrystalline silicon (polysilicon), or silicon nitride (silicon nitride) may be polished. Depending on the structure of the transistor, the polishing rate of each Si-containing material is set to some extent. There is a need to control.

  For example, according to Patent Document 2, a technique for polishing polysilicon with an acidic abrasive containing acid, abrasive grains and the like is disclosed.

U.S. Pat. No. 4,944,836 JP 2006-035771 A

  However, even with the polishing composition described in Patent Document 2, the polishing rate of the Si-containing material cannot be sufficiently controlled, and further improvement has been desired.

  Then, an object of this invention is to provide the polishing composition which can fully control the polishing rate of Si containing material.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, a pH adjuster and an organic compound are contained, and the organic compound is represented by the following formula (1):

  However, it has been found that A can be solved by providing a polishing composition represented by A being an electron-attracting group and having a pH of more than 7.5.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing composition which can fully control the polishing rate of Si containing material can be provided.

  The present invention will be described below. In addition, this invention is not limited only to the following embodiment. In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH.

<Polishing composition>
The present invention contains a pH adjuster and an organic compound, and the organic compound is represented by the following formula (1):

  However, A is polishing composition which is represented by the electron withdrawing group and whose pH is more than 7.5.

  According to the polishing composition having such a configuration, the polishing rate of the Si-containing material can be sufficiently controlled. Although the detailed reason for such an effect is unclear, it is presumed to be due to the following mechanism.

  That is, the polishing composition of the present invention contains an organic compound, and the organic compound is represented by the following formula (1):

  However, A is represented by an electron withdrawing group.

When such an organic compound is contained in the polishing composition, delocalization of electrons in the benzene ring of the organic compound is suppressed, so that the chemical relationship between the electron withdrawing group and the material surface is reduced. It is considered that the polishing rate of the Si-containing material typified by silicon or polysilicon can be suppressed to an appropriate level by the action. The organic compounds of the present invention have a nitro group (-NO ₂₎ required. Similarly, the nitro group (—NO ₂ ) usually functions as an electron withdrawing group, but “A” in the organic compound of the present invention is such that the nitro group (—NO ₂ ) and the surface of the Si-containing material are electrons. It is considered that the polishing rate of Si-containing materials typified by silicon and polysilicon can be suppressed to an appropriate level by interacting and producing a synergistic effect.

  In addition, the polishing composition of the present invention contains a pH adjuster and is set so that the pH exceeds 7.5. When the pH is 7.5 or less, the surface of the Si-containing material becomes hydrophobic, and thus surface defects occur. In addition, the polishing rate becomes too low, and the throughput may deteriorate.

  However, the above mechanism is based on speculation, and the present invention is not limited to the above mechanism.

[Organic compounds]
As described above, the organic compound of the present invention has the following formula (1):

  However, A is represented by an electron withdrawing group.

The A, is not particularly limited as long as it is a monovalent group having an _{electron-withdrawing, -OH, -F, -Cl, -Br} , -I, -CF 3, -CCl 3, -CBr 3, - CN, —COR, —CON (R) ₂ , —SO ₂ R, —P (═O) (OR) ₂ , —CO ₂ R, —C (O) R, —COSR, etc. “R” is each independently —H, —OH, —CH ₃ or —C ₂ H ₅ .

  The electron withdrawing group may be in the form of a salt such as sodium salt, potassium salt, or ammonium salt.

From the viewpoint of reactivity with Si, —OH, —COR, —SO ₂ R, and —P (═O) (OR) ₂ are more preferable.

  There is no particular limitation on the substitution position of A. From the nitro group, it may be ortho, meta or para.

  Thus, according to a preferred embodiment of the present invention, the organic compound is nitrophenol, nitrobenzoic acid, nitrobenzenesulfonic acid or nitrophenylphosphonic acid. In such a form, the organic compound is bonded to the Si-containing material and has a technical effect of more effectively controlling the polishing rate of the Si-containing material.

  Although there is no restriction | limiting in particular in content of the organic compound in the polishing composition of this invention, From a soluble viewpoint, 0.001 mass% or more is preferable, 0.005 mass% or more is more preferable, 0.01 mass % Or more is more preferable, and 0.03% by mass or more is more preferable.

  On the other hand, from the viewpoint of reactivity with the Si surface, 1.0% by mass or less is preferable, 0.5% by mass or less is more preferable, and 0.1% by mass or less is more preferable.

[PH adjuster]
The polishing composition of the present invention has a pH of more than 7.5. If the pH is 7.5 or less, the surface of the Si-containing material becomes hydrophobic, and surface defects such as adhesion of organic substances may occur. In addition, the polishing rate becomes too low, and the throughput may deteriorate.

  The polishing composition of the present invention may have a pH of more than 7.5, but is preferably 8 or more, more preferably 9 or more. In such an environment with a relatively high pH, dissolution of the polishing object proceeds and a high polishing rate (also referred to as “polishing rate” in the present specification) can be realized. However, the polishing rate may be too high. In particular, when it is 2000 Å / min or more, there is a possibility of leading to device failure. However, since the polishing composition of the present invention contains a specific organic compound, there is an advantage that the polishing rate can be suppressed in a region / environment where such a high polishing rate is maintained. .

  The upper limit of the pH is not particularly limited, but is less than 14, preferably 12 or less, more preferably 11 or less. By setting it as such an upper limit, handling of polishing composition becomes easy.

  Specific examples that can be used as the pH adjuster may be either inorganic compounds or organic compounds, but are preferably alkaline (base), alkali metal hydroxides or salts thereof, alkaline earth metals Or a salt thereof, quaternary ammonium hydroxide or a salt thereof, ammonia, an amine and the like. Specific examples of the alkali metal include potassium and sodium. Specific examples of the salt include carbonate, hydrogen carbonate, sulfate, acetate, and the like. Specific examples of the quaternary ammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like.

  The quaternary ammonium hydroxide compound includes quaternary ammonium hydroxide or a salt thereof, and specific examples thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide and the like.

  Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, guanidine and the like. These bases may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these bases, ammonia, ammonium salts, alkali metal hydroxides, alkali metal salts, quaternary ammonium hydroxide compounds, and amines are preferable. More preferably, ammonia, potassium compound, sodium hydroxide, potassium hydroxide, quaternary ammonium hydroxide compound, ammonium bicarbonate, ammonium carbonate, sodium bicarbonate, and sodium carbonate are applied. Moreover, it is more preferable that the polishing composition contains a potassium compound as a base from the viewpoint of preventing metal contamination. Examples of the potassium compound include potassium hydroxide or salt, and specific examples include potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium sulfate, potassium acetate, potassium chloride and the like.

  In addition, an acid pH adjuster may be used as appropriate. Specific examples of the acid include inorganic acids such as sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid; 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, Examples thereof include carboxylic acids such as tartaric acid, citric acid and lactic acid, and organic acids such as organic sulfuric acid such as methanesulfonic acid, ethanesulfonic acid and isethionic acid. In the present invention, when an acid pH adjuster is used, it is usually used in combination with a base pH adjuster.

[Abrasive grain]
The polishing composition of the present invention preferably contains abrasive grains.

  The abrasive used 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, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. These abrasive grains may be used alone or in combination of two or more. The abrasive grains may be commercially available products or synthetic products.

  Among these abrasive grains, silica is preferable, and colloidal silica is particularly preferable from the viewpoint of suppressing generation of polishing flaws.

  The abrasive grains may be surface-modified. Such surface-modified abrasive grains are 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 or fixing an organic acid. Can do. Of these, colloidal silica having an organic acid immobilized thereon is particularly preferred. The organic acid is immobilized on the surface of the colloidal silica contained in the polishing composition, for example, by chemically bonding a functional group of the organic acid to the surface of the colloidal silica. If the colloidal silica and the organic acid are simply allowed to coexist, the organic acid is not fixed to the colloidal silica. For immobilizing sulfonic acid, which is a kind of organic acid, on colloidal silica, see, for example, “Sulphonic acid-functionalized silica through quantitative oxides of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica, and then the sulfonic acid is immobilized on the surface by oxidizing the thiol group with hydrogen peroxide. The colloidal silica thus obtained can be obtained. Alternatively, if the carboxylic acid is immobilized on colloidal silica, for example, “Novel Silene Coupling Agents Containing a Photolabile 2-Nitrobenzoyl Ether for the Introducing the Carboxy Group” 229 (2000). Specifically, colloidal silica having a carboxylic acid immobilized on the surface can be obtained by irradiating light after coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica. .

  The abrasive grains in the polishing composition are not limited to true spheres, and preferably have a certain aspect ratio. The upper limit of the aspect ratio is preferably less than 1.4, more preferably 1.3 or less, and even more preferably 1.25 or less. Within such a range, the surface roughness caused by the shape of the abrasive grains can be made favorable. There is also a technical effect that the polishing rate of the Si-containing material can be controlled more appropriately.

  The aspect ratio is an average of values 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 shorter side of the same rectangle, It can be obtained using general image analysis software. In addition, in the Example, it calculated | required using Mac-view made by Mountec.

  The lower limit of the average primary particle diameter of the abrasive grains in the polishing composition is preferably 5 nm or more, more preferably 7 nm or more, further preferably 10 nm or more, and still more preferably 20 nm or more. Yes, particularly preferably 25 nm or more. Further, the upper limit of the average primary particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, further preferably 100 nm or less, still more preferably 70 nm or less, and further preferably 50 nm or less. It is particularly preferred.

  Within such a range, the polishing rate of the object to be polished by the polishing composition can be controlled more appropriately, and dishing occurs on the surface of the object to be polished after polishing with the polishing composition. It can be suppressed more.

  In addition, the average primary particle diameter of an abrasive grain is 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 in the polishing composition is preferably 25 nm or more, more preferably 30 nm or more, further preferably 35 nm or more, and preferably 40 nm or more. Even more preferably, it is particularly preferably 50 nm or more. The upper limit of the average secondary particle diameter of the abrasive grains is preferably 300 nm or less, more preferably 260 nm or less, further preferably 220 nm or less, still more preferably 150 nm or less, and more preferably 100 nm or less. Particularly preferred. Within such a range, the polishing rate of the polishing object by the polishing composition can be controlled more appropriately, and surface defects occur on the surface of the polishing object after polishing with the polishing composition. Can be further suppressed.

  The secondary particles referred to here are particles formed by association of abrasive grains in the polishing composition, and the average secondary particle diameter of the secondary particles is measured by, for example, a dynamic light scattering method. be able to.

  In the particle size distribution obtained by the laser diffraction scattering method in the abrasive grains in the polishing composition, the particle diameter D90 when the cumulative particle weight reaches 90% of the total particle weight from the fine particle side and 10 of the total particle weight of all the particles. %, The lower limit of the ratio D90 / D10 with respect to the particle diameter D10 is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.5 or more. preferable.

  Further, in the particle size distribution obtained by the laser diffraction scattering method in the abrasive grains in the polishing composition, the particle diameter D90 and the total particle weight of all particles when the cumulative particle weight reaches 90% of the total particle weight from the fine particle side. The upper limit of the ratio D90 / D10 with respect to the particle diameter D10 when reaching 10% is not particularly limited, but is preferably 5.0 or less, more preferably 3.0 or less, and 2.2 The following is even more preferable.

  Within such a range, the polishing rate of the object to be polished can be controlled more appropriately, and the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition can be further suppressed. it can.

  The lower limit of the content of the abrasive grains in the polishing composition is preferably 0.005% by mass or more, more preferably 0.05% by mass or more, and 0.5% by mass or more. More preferably, it is more preferably 1% by mass or more, and particularly preferably 3% by mass or more. When the lower limit is such, the polishing rate is improved.

  Further, the upper limit of the content of the abrasive grains in the polishing composition is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less, 15 More preferably, it is more preferably 10% by mass or less. When the upper limit is such, the cost of the polishing composition can be suppressed, and the occurrence of surface defects on the surface of the object to be polished after polishing using the polishing composition can be further suppressed.

[Other ingredients]
The polishing composition of the present invention may further contain other components such as an oxidant, a complexing agent, a surfactant, a water-soluble polymer, a metal anticorrosive, a fungicide, and a preservative, as necessary. . However, when there are those which are included in the scope of the organic compound of the present invention and also have the following functions, they are classified as the above organic compounds.

  Hereinafter, the oxidizing agent, complexing agent, surfactant, water-soluble polymer, antiseptic and antifungal agent will be described.

(Oxidant)
Specific examples of the oxidizing agent include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate. These oxidizing agents may be used alone or in combination of two or more. Among them, persulfate and hydrogen peroxide are preferable, and hydrogen peroxide is particularly preferable.

  The lower limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more. By setting the lower limit in this way, there is an advantage that the polishing rate by the polishing composition is improved. Moreover, it is preferable that the upper limit of content (concentration) of the oxidizing agent in polishing composition is 10 mass% or less, More preferably, it is 5 mass% or less. By setting the upper limit in this way, the material cost of the polishing composition can be suppressed, and in addition, there is an advantage that the load of the treatment of the polishing composition after polishing use, that is, the waste liquid treatment can be reduced. . In addition, there is an advantage that excessive oxidation of the surface of the object to be polished by the oxidizing agent hardly occurs.

(Complexing agent)
The complexing agent has an action of chemically etching the surface of the object to be polished, and improves the polishing rate of the object to be polished by the polishing composition.

  Examples of complexing agents that can be used include inorganic acids or salts thereof, organic acids or salts thereof, nitrile compounds, amino acids, and chelating agents. These complexing agents may be used alone or in admixture of two or more. The complexing agent may be a commercially available product or a synthetic product.

  Specific examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, boric acid, tetrafluoroboric acid, hypophosphorous acid, phosphorous acid, phosphoric acid, pyrophosphoric acid and the like.

  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, monovalent carboxylic acids such as n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, lactic acid, glycolic acid, glyceric acid, benzoic acid, salicylic acid; oxalic acid, malonic acid, succinic acid, Examples thereof include carboxylic acids such as glutaric acid, gluconic acid, adipic acid, pimelic acid, maleic acid, phthalic acid, fumaric acid, malic acid, tartaric acid and citric acid. Also, sulfonic acids such as methanesulfonic acid, ethanesulfonic acid and isethionic acid can be used.

  As a complexing agent, the inorganic acid or the salt of the organic acid may be used. In particular, when a salt of a weak acid and a strong base, a salt of a strong acid and a weak base, or a salt of a weak acid and a weak base is used, a pH buffering action can be expected. Examples of such salts include, for example, potassium chloride, sodium sulfate, potassium nitrate, potassium carbonate, potassium tetrafluoroborate, potassium pyrophosphate, potassium oxalate, trisodium citrate, (+)-potassium tartrate, hexafluoro A potassium phosphate etc. are mentioned.

  Specific examples of the nitrile compound include acetonitrile, aminoacetonitrile, propionitrile, butyronitrile, isobutyronitrile, benzonitrile, glutaronitrile, methoxyacetonitrile, and the like.

  Specific examples of amino acids include 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, canavanine, cytosine Phosphorus, .delta.-hydroxy - lysine, creatine, histidine, 1-methyl - histidine, 3-methyl - include histidine and tryptophan.

  Specific examples of chelating agents include nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylenediamine-N, N, N ′, N′-tetramethylenesulfonic acid, transcyclohexane Diamine tetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diamine tetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), N- (2-carboxylateethyl) -L-aspartic acid, β -Alanine diacetate, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid 1,2-dihydroxybenzene-4,6 Such as disulfonic acid and the like.

  Among these, at least one selected from the group consisting of an inorganic acid or a salt thereof, a carboxylic acid or a salt thereof, and a nitrile compound is preferable, from the viewpoint of the stability of the complex structure with the metal compound contained in the polishing object. An inorganic acid or a salt thereof is more preferable. Moreover, when using what has pH adjustment function (for example, various acids etc.) as various complexing agents mentioned above, you may utilize the said complexing agent as at least one part of a pH adjusting agent.

  The lower limit of the content (concentration) of the complexing agent in the polishing composition is not particularly limited because it exhibits an effect even in a small amount, but is preferably 0.001 g / L or more, more preferably 1 g / L or more. By setting such a lower limit, the polishing rate is improved. In addition, the upper limit of the content (concentration) of the complexing agent in the polishing composition of the present invention is preferably 20 g / L or less, more preferably 15 g / L or less. By setting it as such an upper limit, melt | dissolution is prevented and a level | step difference elimination property is improved.

(Surfactant)
A surfactant may be contained in the polishing composition. The surfactant improves the cleaning efficiency after polishing by imparting hydrophilicity to the polished surface after polishing, and can prevent the adhesion of dirt. The surfactant may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

  Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate ester, alkyl sulfate ester, polyoxyethylene alkyl sulfate, alkyl sulfate, alkylbenzene sulfonic acid, alkyl phosphate ester, polyoxyethylene ester Ethylene alkyl phosphate ester, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, salts thereof and the like are included.

  Specific examples of the cationic surfactant include alkyltrimethylammonium salt, alkyldimethylammonium salt, alkylbenzyldimethylammonium salt, alkylamine salt and the like.

  Specific examples of amphoteric surfactants include alkyl betaines and alkyl amine oxides. Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, alkyl alkanolamide, and the like. It is. One of these surfactants may be used alone, or two or more thereof may be used in combination.

  The content of the surfactant in the polishing composition is preferably 0.0001 g / L or more, more preferably 0.001 g / L or more. By setting it as such a lower limit, the cleaning efficiency after polishing is further improved. The content of the surfactant in the polishing composition is preferably 10 g / L or less, more preferably 1 g / L or less. By setting it as such a lower limit, the residual amount of the surfactant on the polished surface is reduced, and the cleaning efficiency is further improved.

(Water-soluble polymer)
Specific examples of the water-soluble polymer include, for example, polystyrene sulfonate, polyisoprene sulfonate, polyacrylate, polymaleic acid, polyitaconic acid, polyvinyl acetate, polyvinyl alcohol, polyglycerin, polyvinyl pyrrolidone, and isoprene sulfonic acid. And acrylic acid copolymer, polyvinylpyrrolidone polyacrylic acid copolymer, polyvinylpyrrolidone vinyl acetate copolymer, salt of naphthalenesulfonic acid formalin condensate, diallylamine hydrochloride sulfur dioxide copolymer, carboxymethylcellulose, carboxymethylcellulose Examples include salts, hydroxyethyl cellulose, hydroxypropyl cellulose, pullulan, chitosan, and chitosan salts. When a water-soluble polymer is added to the polishing composition, the surface roughness of the polishing object after polishing using the polishing composition is further reduced. One of these water-soluble polymers may be used alone, or two or more thereof may be used in combination.

  The content of the water-soluble polymer in the polishing composition is preferably 0.0001 g / L or more, more preferably 0.001 g / L or more. By setting it as such a lower limit, the surface roughness of the polishing surface by the polishing composition is further reduced. The content of the water-soluble polymer in the polishing composition is preferably 10 g / L or less, more preferably 1 g / L or less. By setting such an upper limit, the remaining amount of the water-soluble polymer on the polishing surface is reduced, and the cleaning efficiency is further improved.

(Preservatives and fungicides)
Examples of the antiseptic and fungicide that can be added to the polishing composition according to the present invention include 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one. And the like, and isothiazoline preservatives such as paraoxybenzoic acid esters and phenoxyethanol. These antiseptics and fungicides may be used alone or in combination of two or more.

[Dispersion medium or solvent]
In the polishing composition of the present invention, a dispersion medium or a solvent for dispersing or dissolving each component can be usually used. As the dispersion medium or solvent, an organic solvent and water are conceivable, and among them, water is preferably included. From the viewpoint of inhibiting the action of other components, water containing as little impurities as possible is preferable. Specifically, pure water, ultrapure water, or distilled water from which foreign ions are removed through a filter after removing impurity ions with an ion exchange resin is preferable.

<Method for producing polishing composition>
In this invention, it is a manufacturing method of polishing composition, Comprising: A pH adjuster and an organic compound are mixed, The said organic compound is following formula (1):

  However, there is also provided a method for producing a polishing composition, wherein A is an electron-attracting group, and the pH is more than 7.5.

  For example, the above-described method for producing a polishing composition can be obtained by stirring and mixing each component constituting the polishing composition of the present invention and, if necessary, other components in a dispersion medium or a solvent. it can.

  Although the temperature at the time of mixing each component is not specifically limited, 10-40 degreeC is preferable and you may heat in order to raise a dissolution rate. Further, the mixing time is not particularly limited.

<Polishing object>
The polishing composition of the present invention is suitable for polishing an object to be polished having a layer containing a Si-containing material. Examples of the Si-containing material include silicon, simple silicon, and silicon compounds.

  Examples of the single silicon include single crystal silicon, polycrystalline silicon (polysilicon), and amorphous silicon.

  Examples of the silicon compound include silicon nitride, silicon oxide, silicon oxide, silicon carbide, and silicon nitride. The silicon compound film includes a low dielectric constant film having a relative dielectric constant of 3 or less.

  In a preferred embodiment of the present invention, at least one selected from the group consisting of silicon, polycrystalline silicon, silicon oxide, and silicon nitride.

  Single crystal silicon and polycrystalline silicon are preferable.

<Polishing method>
In this invention, the grinding | polishing method which grind | polishes a grinding | polishing target object with said polishing composition or the polishing composition obtained by said manufacturing method is provided.

  As a polishing apparatus, a general holder having a polishing surface plate on which a holder for holding a substrate having a polishing object and a motor capable of changing the number of rotations are attached and a polishing pad (polishing cloth) can be attached. A polishing apparatus can be used.

  As the polishing pad, a general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used without particular limitation. It is preferable that the polishing pad is grooved so that the polishing composition accumulates.

  The polishing conditions are not particularly limited. For example, the rotation speed of the polishing platen and the carrier rotation speed are preferably independently 10 to 500 rpm, and the pressure applied to the substrate having the object to be polished (polishing pressure) is 0. .1-10 psi is preferred. The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying with a pump or the like is employed. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

  After polishing, the substrate is washed in running water, and water droplets adhering to the substrate are removed by drying with a spin dryer or the like, and dried to obtain a substrate having a layer containing Si material.

  The preferable polishing rate when polishing with the polishing composition of the present invention is preferably 1000 Å / min or more and less than 2000 Å / min, more preferably 1500 to 1980 Å / min, and further preferably 1850 to 1950 Å. / Min.

  The present invention will be described in further detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

(Preparation of polishing composition)
A polishing composition was prepared by mixing abrasive grains, a pH adjuster and an organic compound in ultrapure water with the composition shown in Table 1 below (mixing temperature: about 25 ° C., mixing time: about 10 minutes). . The pH of the polishing composition (liquid temperature: 25 ° C.) was confirmed by a pH meter (manufactured by Horiba, Ltd., model number: LAQUA). “-” In Table 1 indicates that it was not added.

(Polishing performance evaluation)
Using the obtained polishing composition, the polishing rate when the silicon substrate was polished under the following polishing conditions was measured.

Polishing conditions Polishing machine: Single-side CMP polishing machine (ENGIS; manufactured by Engis Japan Ltd.)
Polishing pad: Polyurethane pad Pressure: 3.0 psi (20.7 kPa)
Plate rotation speed: 60rpm
Carrier rotation speed: 60rpm
Flow rate of polishing composition: 100 ml / min
Polishing time: 120 sec
The polishing rate was calculated by the following formula.

  The film thickness was evaluated using an optical interference type film thickness measuring device (model number: Lambda Ace, manufactured by Dainippon Screen Mfg. Co., Ltd.) and dividing the difference by the polishing time.

  The measurement results of the polishing rate are shown in Table 1 below.

<Discussion>
In Examples 1 and 2, the polishing composition has a pH of more than 7.5 and contains a specific organic compound. Because of such a configuration, it is possible to keep the polishing rate to 2000 kg / min or less while maintaining a high polishing rate.

  On the other hand, although the pH is over 7.5, in Comparative Example 1 using a polishing composition that does not contain a specific organic compound, the polishing rate is 2000 kg / min or more. At such a high polishing rate, there is a risk of device failure. On the other hand, in Comparative Example 2 using a polishing composition containing a specific organic compound but having a pH of 7.5 or less, the polishing rate is less than 1000 kg / min. At such a low polishing rate, the throughput may be deteriorated.

  In addition, this application is based on the Japan patent application 2014-197453 for which it applied on September 26, 2014, The indication content is quoted as a whole by reference.

Claims (5)

A polishing composition used in an application for polishing a polishing object having a layer containing a Si-containing material,
The polishing composition contains a pH adjuster, an organic compound, and abrasive grains,
The organic compound is represented by the following formula (1):

However, A is an electron withdrawing group, in expressed, the electron withdrawing _{group, -OH, -F, -Cl, -Br} , -I, -CF 3, -CCl 3, -CBr 3, —CN, —COR, —CON (R) ₂ , —P (═O) (OR) ₂ , —CO ₂ R, —C (O) R or —COSR, wherein each R is independently H, —OH, —CH ₃ or —C ₂ H ₅ ;
The abrasive is silica;
The Si-containing material is at least one of silicon and polycrystalline silicon;
pH 7.5 ultra der is, contains no oxidizing agent, the polishing composition. The polishing composition according to claim 1, wherein the electron withdrawing group is —OH, —COR, or —P (═O) (OR) ₂ .   The polishing composition according to claim 1 or 2, wherein the organic compound is nitrophenol, nitrobenzoic acid, or nitrophenylphosphonic acid. A method for producing a polishing composition used in an application for polishing a polishing object having a layer containing a Si-containing material,
having a pH adjuster, an organic compound, and abrasive grains, except that the oxidizer is not mixed,
The organic compound is represented by the following formula (1):

However, A is an electron withdrawing group, in expressed, the electron withdrawing _{group, -OH, -F, -Cl, -Br} , -I, -CF 3, -CCl 3, -CBr 3, —CN, —COR, —CON (R) ₂ , —P (═O) (OR) ₂ , —CO ₂ R, —C (O) R or —COSR, wherein each R is independently H, —OH, —CH ₃ or —C ₂ H ₅ ;
The abrasive is silica;
The Si-containing material is at least one of silicon and polycrystalline silicon;
A method for producing a polishing composition, wherein the pH is more than 7.5. A polishing object having a layer containing a Si-containing material is polished with the polishing composition according to any one of claims 1 to 3 or the polishing composition obtained by the production method according to claim 4 , A polishing method, wherein the Si-containing material is at least one of silicon and polycrystalline silicon.