TW201619346A - Polishing composition and polishing method using same - Google Patents

Abstract

The present invention provides a polishing composition capable of adequately limiting dishing phenomena in polishing steps and of more reliably eliminating level differences. The present invention is a polishing composition: which contains silica on the surface of which an organic acid has been fixed and a polyoxyalkylene group-containing compound; for which the molecular weight distribution of the weight average molecular weight (calculated as polyethylene glycol) of the polyoxyalkylene group-containing compound by gel permeation chromatography (GPC) has at least two peaks; and for which the pH is not more than 7.

Description

Grinding composition and grinding method using same

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

In the semiconductor device manufacturing process, as the performance of the semiconductor device is improved, it is necessary to have a technique in which wiring is manufactured at a higher density and in a high-volume manner. In such a manufacturing process of a semiconductor device, CMP (Chemical Mechanical Polishing) is an essential process. With the development of the miniaturization of semiconductor circuits, the flatness required for the unevenness of the pattern wafer is improved, and high flatness of the nanometer level is required by CMP. Preferably, in order to achieve high smoothness by CMP, the convex portion of the pattern wafer is polished at a high polishing rate, and on the other hand, the concave portion is not polished.

The semiconductor wafer is composed of a polycrystalline germanium forming a circuit, a tantalum oxide as an insulating material, and a heterogeneous material for protecting a non-groove or a portion of the ceria from being damaged by etching. Therefore, a material such as polycrystalline ruthenium or ruthenium oxide which is relatively soft and which is easily reacted with an abrasive is more likely to be caused than a tantalum nitride or the like around it. The degree of scraping is called the phenomenon of dents, and there is a problem that causes the step difference to remain.

Based on such problems, in the polishing step of the pattern wafer composed of a hard and chemically stable material such as tantalum nitride, it is required to sufficiently cancel the step.

As a technique for responding to such a request, for example, in JP-A-2012-040671 (corresponding to the specification of U.S. Patent Application Publication No. 2013/146804), a polishing composition is disclosed which can be used. A polishing composition which is polished at a higher speed than a polycrystalline ruthenium or the like, which contains a colloidal cerium oxide to which an organic acid is immobilized, and has a pH of 6 or less. .

However, the conventional polishing composition has a problem that the above-described depression phenomenon cannot be sufficiently suppressed, and the step difference cannot be sufficiently released.

Accordingly, the present invention has an object of providing a polishing composition which can sufficiently suppress the dishing phenomenon in the polishing step and more reliably cancel the step.

In order to solve the above problems, the inventors have accumulated efforts to study. As a result, it has been found that a compound having a polyoxyalkylene (also referred to as "polyoxyalkylene-containing compound" in the present specification) is used in a molecular weight distribution of a weight average molecular weight measured by gel permeation chromatography (GPC). The present invention has been accomplished by using a compound having two or more peaks and using it in combination with cerium oxide having an organic acid immobilized on its surface.

That is, the present invention relates to a polishing composition comprising a cerium oxide and a polyoxyalkylene-containing compound having an organic acid immobilized on a surface thereof, and a gel permeation chromatography for the polyoxyalkylene-containing compound ( The molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) obtained by GPC) has two or more peaks and a pH of 7 or less.

Hereinafter, the present invention will be described.

<grinding composition>

According to an aspect of the present invention, there is provided a polishing composition comprising a cerium oxide and a polyoxyalkylene-containing compound having an organic acid immobilized on a surface thereof, and a gel permeation layer for the polyoxyalkylene-containing compound. The molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) obtained by the precipitation method (GPC) has two or more peaks and a pH of 7 or less. According to the polishing composition of the present invention having such a configuration, the depression phenomenon in the polishing step can be sufficiently suppressed, and the step can be more reliably released.

Though the polishing composition of the present invention is used, the reason why the depression phenomenon in the polishing step can be sufficiently suppressed, and the details of the step difference is more reliably eliminated is not clear, but it is presumed to be due to the following mechanism.

In the case of the "water-soluble polymer" as disclosed in JP-A-2012-040671 (corresponding to the specification of U.S. Patent Application Publication No. 2013/146804), it is also known that it can be used in the polishing composition. A polyoxyalkylene-containing compound such as polyethylene glycol (PEG) is added. Presumably When such a compound is used, it is adsorbed on the surface of the object to be polished such as polycrystalline ruthenium by the action of a hydrogen bond or the like, and the surface of the object to be polished is protected from the mechanical action by the abrasive grains. The polishing rate of the object to be polished by the polishing composition is controlled. Here, it is presumed that, as in the present invention, since the composition for polishing contains a polyoxyalkylene-containing compound having a molecular weight distribution of two or more peaks, a compound having a small molecular weight is buried as Further, it is adsorbed to the gap which is adsorbed by the compound having a large molecular weight, and as a result, a dense protective film can be formed on the surface of the object to be polished, and the function of releasing the step is further exerted.

Further, when the polishing composition of the present invention is used for polishing the material to be polished, the polishing rate of SiN which is an object to be polished can be maintained or improved, and the polishing with polycrystalline germanium or TEOS can be further suppressed. The effect of the polishing rate of the layer of the material different in the object, the material to be polished contains tantalum nitride (SiN) as the object to be polished, and contains polycrystalline germanium or tetraethyl orthophthalate (TEOS) as the inclusion and polishing. A layer of material that is different from the object. The polishing rate of SiN is actually 50 Å/min or more at the time of polishing and polishing, and is 100 Å/min or more at the time of pattern polishing. However, in the case of using the polishing composition of the present invention, it is possible to maintain or enhance the polishing of such SiN. The speed is sufficient, and the depression in the grinding step is sufficiently suppressed, and the step is more reliably released.

In addition, since the above mechanism is derived from the speculation, the present invention is not limited by the above mechanism. Hereinafter, the configuration of the polishing composition according to one embodiment of the present invention will be described in detail.

[Antimony oxide with organic acid fixed on the surface]

The "cerium oxide having an organic acid fixed to the surface" contained in the polishing composition of the present invention is used as a fine particle of an organic acid which is bonded to the surface as an abrasive particle. The above-mentioned cerium oxide includes fumed silica or colloidal cerium oxide, and the like, but colloidal cerium oxide is particularly preferable. The organic acid is not particularly limited, and examples thereof include a sulfonic acid, a carboxylic acid, a phosphoric acid, and the like, and a sulfonic acid or a carboxylic acid is preferred. In addition, the surface of the "cerium oxide having an organic acid fixed on the surface" contained in the polishing composition of the present invention is fixed by the covalent bonding (via a connection structure depending on the case). An acidic group of an organic acid (for example, a sulfo group, a carboxyl group, a phosphate group, etc.).

A synthetic product may be used as the cerium oxide having an organic acid fixed on its surface, and a commercially available product may also be used. Further, the cerium oxide system in which an organic acid is fixed to the surface may be used singly or in combination of two or more kinds.

The method of introducing the organic acid to the surface of the ceria is not particularly limited, and it is also introduced in the form of a mercapto group or an alkyl group, and then is introduced into the surface of the ceria and then oxidized to a sulfonic acid or a carboxylic acid. A method in which a protective group is bonded to a surface of a ceria based on an acidic group derived from the above organic acid, and then the protective group is removed. Further, the compound to be used when introducing an organic acid to the surface of the ceria preferably comprises a bond having at least one functional group capable of forming an organic acid group and further bonding to a hydroxyl group on the surface of the ceria. A functional group, a functional group introduced to control hydrophobicity/hydrophilicity, a functional group introduced to control steric volume expansion, and the like.

As a specific synthesis method of the cerium oxide having an organic acid immobilized on the surface, if the sulfonic acid which is one of the organic acids is fixed to the surface of the cerium oxide, for example, "Sulfonic acid-functionalized silica through quantitative" The method described in oxidation of thiol groups", Chem. Commun. 246-247 (2003). Specifically, by coupling a decane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxydecane to cerium oxide, the thiol group is oxidized by hydrogen peroxide, whereby the surface is immobilized. Ceria bismuth oxide. Alternatively, if the carboxylic acid is immobilized on the surface of the cerium oxide, for example, "Novel Silane Coupling Agents Containing a Photo labile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel", Chemistry Letters, The method described in 3,228-229 (2000) is carried out. Specifically, by coupling a decane coupling agent containing a photoreactive 2-nitrobenzyl ester to cerium oxide and then performing light irradiation, cerium oxide having a carboxylic acid immobilized on the surface thereof can be obtained.

The average primary particle diameter of the cerium oxide to which the organic acid is fixed on the surface in the polishing composition is preferably 5 nm or more, more preferably 7 nm or more, still more preferably 10 nm or more. There is an advantage in that the polishing rate of the object to be polished by the polishing composition is increased as the average primary particle diameter of the cerium oxide having the organic acid fixed to the surface is increased.

The average primary particle diameter of the cerium oxide to which the organic acid is fixed on the surface in the polishing composition is preferably 50 nm or less, more preferably 45 nm or less, still more preferably 40 nm or less. Has the following advantages: along with the surface The smaller the average primary particle diameter of the cerium oxide to which the organic acid is fixed, the more the scratch on the surface of the object to be polished after polishing with the polishing composition can be suppressed. Further, the value of the average primary particle diameter of the cerium oxide to which the organic acid is immobilized on the surface can be calculated, for example, from the specific surface area of the cerium oxide to which the organic acid is immobilized on the surface as measured by the BET method.

The average secondary particle diameter of the cerium oxide to which the organic acid is fixed on the surface in the polishing composition is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more. There is an advantage in that the polishing rate of the object to be polished by the polishing composition is increased as the average secondary particle diameter of the cerium oxide having the organic acid fixed to the surface is increased.

The average secondary particle diameter of the cerium oxide to which the organic acid is fixed on the surface in the polishing composition is preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less. The smaller the average secondary particle diameter of the cerium oxide to which the organic acid is fixed on the surface, the more the scratch on the surface of the object to be polished after polishing with the polishing composition can be suppressed. Further, the value of the average secondary particle diameter of cerium oxide can be calculated, for example, from the specific surface area of cerium oxide measured by a light scattering method using laser light.

The content of the cerium oxide in which the organic acid is fixed to the surface in the polishing composition is preferably 0.0005 mass% or more, more preferably 0.001 mass% or more, still more preferably 0.005 mass% or more. There is an advantage in that the polishing rate of the object to be polished due to the polishing composition is increased as the content of the cerium oxide to which the organic acid is fixed on the surface is increased.

In the polishing composition, the organic acid is fixed on the surface The content of cerium oxide is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less. It has the advantage that the friction with the material to be polished is reduced as the content of the cerium oxide to which the organic acid is fixed on the surface is reduced, for example, when cerium nitride (SiN) is used as the object to be polished, etc. A polishing rate of a layer of a material different from the object to be polished, such as polycrystalline germanium or TEOS.

Further, in the present invention, it is necessary to use "cerium oxide having an organic acid fixed on its surface" as the abrasive particles, but it may be used in combination with cerium oxide having no organic acid fixed to the surface depending on the case. However, the content of the "cerium oxide having an organic acid fixed on the surface" in the entire abrasive grains is preferably 50% by mass or more, more preferably 80% by mass or more, more preferably, based on the mass. 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass. In addition, when only the "cerium oxide having an organic acid on the surface is not fixed" is used as the abrasive grains, the deterioration of the defect performance due to the aggregates is caused, which is not preferable.

[polyoxyalkylene-containing compound]

The "polyoxyalkylene-containing compound" contained in the polishing composition of the present invention contains an organic compound of a polyoxyalkylene. The "polyoxyalkylene-containing compound" may be a compound in which one of the functional groups of the compound having a polyoxyalkylene is partially substituted or polymerized. These may be used singly or in combination of two or more.

Specific examples of the polyoxyalkylene include polyoxyethylene groups, polyoxypropylene groups, oxyethylene groups and oxypropylene groups or random bonds. The polyoxyalkylene is formed on the polyoxyethylene group, the polyoxypropylene group, or the polyoxyalkylene, and further contains a group of an oxyoxybutenyl group, such as a block or a random bond.

Specific examples of the compound having a hydroxyl group at the terminal of the polyoxyalkylene include various addition amounts of polyethylene glycol, a polyalkylene glycol derivative such as polypropylene glycol or polybutylene glycol, and PRONON (registered trademark) 102. Block polymer represented by PRONON (registered trademark) series such as PRONON (registered trademark) 201 (above, Nippon Oil Co., Ltd.), UNIOL (registered trademark) DA-400, UNIOL (registered trademark) DB-400 UNIOL (registered trademark) DB-530 (above, Nippon Oil Co., Ltd.) and other bisphenol A derivatives.

Specific examples of the compound in which the terminal of the polyoxyalkylene is an ether group include various polyalkylene glycol alkyl ethers such as polyethylene glycol oleyl ether and polyethylene glycol dimethyl ether.

Specific examples of the compound having an ester group at the terminal of the polyoxyalkylene include polyalkylene glycol alkyl groups such as polyethylene glycol monooctyl ester, polypropylene glycol monostearyl ester, and polypropylene glycol distearyl ester. Ester and the like.

Specific examples of the compound in which the terminal of the polyoxyalkylene is an allyl group include UNIOX (registered trademark) PKA-5006, UNIOL (registered trademark) PKA-5014, and UNIOL (registered trademark) PKA-5017 (above, Japanese oil) Various polyalkylene glycol allyl ethers such as those manufactured by Co., Ltd.).

Specific examples of the compound having a (meth)acryl group at the end of the polyoxyalkylene include BLEMI (registered trademark) PP series, BLEMMER (registered trademark) PME series, and BLEMMER (registrar) A polyalkylene glycol (meth) acrylate such as the PDE series (above, manufactured by Nippon Oil Co., Ltd.).

In particular, the polyoxyalkylene-containing compound is preferably one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and more preferably polyethylene glycol.

In the polishing composition of the present invention, the molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) obtained by gel permeation chromatography (GPC) for the above polyoxyalkylene-containing compound has two The points above the peak have characteristics. Here, the phrase "having two or more peaks" means that the graph of the molecular weight distribution obtained by GPC of the polyoxyalkylene-containing compound has two or more maximum values. In general, as described in the column of the method for producing a polishing composition to be described later, a polishing composition can be produced by using two or more kinds of polyoxyalkylene-containing compounds having different weight average molecular weights. A composition having the condition of "having two or more peaks" as described above.

When the molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) obtained by GPC measured on the polyoxyalkylene-containing compound has two or more peaks, the peaks corresponding to the two or more peaks are The weight average molecular weight of at least two of the weight average molecular weights is preferably 1.1 times or more different from each other, more preferably 1.3 times or more, and even more preferably 1.5 times or more. By adopting this configuration, the effects of the present invention can be sufficiently exerted.

Further, when the molecular weight distribution has two peaks, the weight average molecular weight of the peak having a smaller weight average molecular weight is preferably 100~2000, more preferably 100~1000. On the other hand, the weight average molecular weight of the peak of the weight average molecular weight is preferably from 300 to 1,000,000, more preferably from 300 to 100,000.

Further, when the molecular weight distribution system has three or more peaks, among the two peak molecular weights selected from the three or more peaks, the weight average molecular weight of the peak having a smaller weight average molecular weight is preferably 100~ 2000, more preferably 100~1000. Further, among the two peak molecular weights selected from the three or more peaks, the weight average molecular weight of the peak having a large weight average molecular weight is preferably from 300 to 1,000,000, more preferably from 300 to 100,000.

Further, the weight average molecular weight of the polyoxyalkylene-containing compound can be specifically measured by the method described in the examples.

The lower limit of the content of the polyoxyalkylene-containing compound in the polishing composition is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, still more preferably 0.001% by mass or more. Further, the upper limit of the content of the polyoxyalkylene-containing compound in the polishing composition is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less. If it is such a range, the effect of this invention can fully exhibit.

[additive]

The polishing composition of the present invention may also contain an additive. The additive has at least one of a function of increasing the polishing rate of the object to be polished and a function of adjusting the pH of the polishing composition of the present invention.

Examples of such an additive are: formic acid, Acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, lauric acid, myristic acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, linoleic acid, Suzi oleic acid, peanut oleic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, willow Acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acid, ortho-amine benzoic acid a carboxylic acid such as nitrocarboxylic acid; methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, isethionic acid, taurine, etc. Sulfonic acid; inorganic acid such as carbonic acid, hydrochloric acid, nitric acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, sulfuric acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, hexametaphosphoric acid; Diacetic acid, nitrogen triacetic acid, diethylenediamine pentaacetic acid, ethylenediaminetetraacetic acid, N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetra Methyl sulfonate , trans-cyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diamine tetraacetic acid, ethylenediamine o-hydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS body), N -(2-carboxylate ethyl)-L-aspartic acid, β-alanine diacetic acid, 2-phosphonium butane-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-disulfonic acid, poly a chelating agent such as an amine, a polyphosphonic acid, a polyaminocarboxylic acid or a polyaminophosphonic acid, an amine such as an aliphatic amine or an aromatic amine, an organic base such as a quaternary ammonium hydroxide, or potassium hydroxide (KOH). A hydroxide of an alkali metal, a hydroxide of a Group 2 element, and ammonia. These additives may be used singly or in combination of two or more kinds.

Among these additives, preferred are citric acid, phosphoric acid, and amine. Diacetic acid, o-amine benzoic acid, potassium hydroxide.

Among the above-mentioned additives in the polishing composition, the amount of the additive having a function of adjusting the pH may be appropriately selected as the pH of the polishing composition described below. In the case of using an additive having both a function of adjusting the pH and a function of increasing the polishing rate of the object to be polished, such an addition amount can also exhibit an effect of increasing the polishing rate of the object to be polished.

In the case of using an additive having only a function of increasing the polishing rate of the object to be polished, the amount thereof is preferably 0.001% by mass or more, and more preferably 0.01% by mass or more. Moreover, in the case of using an additive having only a function of increasing the polishing rate of the object to be polished, the amount of addition is preferably 30% by mass or less, and more preferably 20% by mass or less.

[pH of the composition for polishing]

The pH of the polishing composition of the present invention has a value of 7 or less. When the value of pH is more than 7, the positive electric charge on the surface of the object to be polished is reduced. Therefore, the abrasive particles having a negative surface charge (cerium oxide having an organic acid fixed on the surface) are used to grind the object to be polished at a high speed. The matter will become difficult. The pH of the polishing composition is preferably 5 or less, more preferably 4 or less, and particularly preferably 3 or less from the viewpoint of polishing the object to be polished at a sufficient polishing rate by the polishing composition.

The value of the pH of the polishing composition is preferably 1 or more, and more preferably 1.5 or more from the viewpoint of safety.

[Dispersing medium or solvent]

The polishing composition of the present invention preferably contains water as a dispersion medium or a solvent. From the viewpoint of preventing the influence of impurities on other components of the polishing composition, it is preferred to use water of high purity as much as possible. Specifically, it is preferred to remove the foreign matter or the ultrapure water or the distilled water after the foreign matter is removed by the filter after the impurity ions are removed by the ion exchange resin. Further, the dispersion medium or the solvent may further contain an organic solvent or the like for the purpose of controlling the dispersibility of the other components of the polishing composition.

[Other ingredients]

The polishing composition of the present invention may further contain other components such as a crosslinking agent, a metal corrosion inhibitor, a preservative, a mold inhibitor, an oxidizing agent, a reducing agent, a surfactant, and a water-soluble polymer, as needed. Hereinafter, an oxidizing agent, a preservative, an antifungal agent, and a water-soluble polymer will be described.

[oxidant]

The oxidizing agent which can be added to the polishing composition has an action of oxidizing the surface of the object to be polished, and raises the polishing rate of the object to be polished by the polishing composition.

Examples of the oxidizing agent that can be used include hydrogen peroxide, sodium peroxide, barium peroxide, organic oxidizing agents, ozone water, silver (II) salts, iron (III) salts, permanganic acid, chromic acid, dichromic acid, and Oxygen disulfate, peroxyphosphoric acid, peroxosulfuric acid, peroxoic acid, peroxyformic acid, peracetic acid, peroxybenzene Formic acid, peroxyphthalic acid, hypochlorous acid, hypobromous acid, hypoiodous acid, chloric acid, chlorous acid, perchloric acid, bromic acid, iodic acid, periodic acid, persulfuric acid, dichloroisotrimer Cyanic acid and the like. These oxidizing agents may be used singly or in combination of two or more kinds. Among these, hydrogen peroxide, ammonium persulfate, periodic acid, hypochlorous acid, and sodium dichloroisocyanurate are preferred.

The content of the oxidizing agent in the polishing composition is preferably 0.1 g/L or more, more preferably 1 g/L or more, still more preferably 3 g/L or more. As the content of the oxidizing agent increases, the polishing rate of the object to be polished by the polishing composition is further increased.

The content of the oxidizing agent in the polishing composition is preferably 200 g/L or less, more preferably 100 g/L or less, still more preferably 40 g/L or less. As the content of the oxidizing agent is reduced, in addition to suppressing the material cost of the polishing composition, the treatment of the polishing composition after polishing, that is, the load of the waste liquid treatment, can be reduced. Further, it is possible to reduce the concern that excessive oxidation of the surface of the object to be polished by the oxidizing agent is caused.

[Preservatives and anti-fungal agents]

Examples of the preservative and the antifungal agent which can be added to the polishing composition of the present invention include 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4. - an isothiazolin-based preservative such as isothiazolin-3-one, a paraben or a phenoxyethanol. These preservatives and antifungal agents may be used alone or in combination of two or more.

[Water soluble polymer]

In the polishing composition of the present invention, a water-soluble polymer may be added for the purpose of improving the hydrophilicity of the surface of the object to be polished or improving the dispersion stability of the abrasive grains. Examples of the water-soluble polymer include hydroxymethylcellulose, hydroxyethylcellulose (HEC), hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, and methylcellulose. a cellulose derivative such as ethyl cellulose, ethyl hydroxyethyl cellulose or carboxymethyl cellulose; an imine derivative such as poly(N-decylalkyleneimine); polyvinyl alcohol; denaturation (cation Denatured or nonionic denatured) polyvinyl alcohol; polyvinylpyrrolidone; polyethylene caprolactam; polyoxyalkylenes such as polyoxyethylene; and copolymers comprising such constituent units. These water-soluble polymers may be used singly or in combination of two or more.

[Manufacturing method of polishing composition]

The method for producing the polishing composition of the present invention is not particularly limited. For example, a method comprising the steps of: ceria having an organic acid immobilized on the surface thereof, and gel permeation chromatography (GPC) can be employed. The molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) is a step of mixing a polyoxyalkylene-containing compound having two or more peaks, and a step of adjusting the pH to 7 or less. At this time, the water and other components as needed may be further stirred and mixed. The details of each component added are as described above.

In addition, among the compounds described in the item of the above [Additives], when a compound having a function of adjusting the pH of the polishing composition of the present invention (for example, various acids or the like) is used, the additive is added. The step of the method can be "the step of adjusting the pH to 7 or less" in the present production method.

The temperature at which the components are mixed is not particularly limited, but is preferably 10 to 40 ° C, and may be heated in order to increase the dissolution rate.

[grinding object]

The object to be polished of the present invention is not particularly limited, and examples thereof include a nitride such as tantalum nitride, an alloy such as aluminum-magnesium or bismuth-tellurium, or a material to be polished of the composite material or the like. Further, examples of the object to be polished containing the ruthenium-containing material include elemental ruthenium and ruthenium compounds. Examples of the elemental lanthanide include single crystal ruthenium, polycrystalline ruthenium (polycrystalline iridium, poly-Si), and amorphous ruthenium. Examples of the ruthenium compound include ruthenium nitride, ruthenium oxide, ruthenium carbide, and SiGe. A low dielectric film having a relative dielectric constant of 3 or less is contained in the ruthenium compound film. Further, the object to be polished is particularly excellent in containing polycrystals.

Further, the object to be polished may also contain a metal. The metal is not particularly limited, and examples thereof include tungsten, copper, aluminum, ruthenium, cobalt, nickel, titanium, rhodium, titanium, cobalt, gold, silver, platinum, palladium, rhodium, iridium, ruthenium, osmium, iridium, and the like. These metals may be included in the form of an alloy or a metal compound. In the case where the object to be polished contains a metal, copper is preferable. These polishing target systems may be used alone or in combination of two or more. Further, the object to be polished may have a single layer structure or a multilayer structure of two or more types. In the case of a multilayer construction, each layer may comprise the same material or may comprise a different material.

Further, the object to be polished of the present invention may have a layer of the above-described object to be polished and a material different from the object to be polished. For example, in the case where the object to be polished is a ruthenium compound such as tantalum nitride (SiN), examples of the material different from the object to be polished include polycrystalline ruthenium, single crystal ruthenium, and tetraethyl ortho-ruthenate ( TEOS) and so on. These materials may be used alone or in combination of two or more.

[Using a grinding method with a polishing composition]

According to another aspect of the present invention, a polishing method for polishing an object to be polished (for example, a polycrystalline silicon wafer) using the polishing composition of the present invention can be provided. Moreover, according to another aspect of the present invention, a method of manufacturing a substrate including a step of polishing an object to be polished (for example, a wafer of a polycrystalline silicon) by the above-described polishing method may be provided.

When the object to be polished is polished using the polishing composition of the present invention, it can be carried out using a device or a condition used in usual polishing. As a general polishing apparatus, there is a single-side polishing apparatus or a double-side polishing apparatus. In the single-side polishing apparatus, by holding a substrate using a holder called a carrier, the polishing composition is attached to the opposite surface of the substrate while the polishing composition is supplied from above. The plate rotates while grinding one side of the material being ground. At this time, the polishing action is performed by the physical action caused by the friction between the polishing pad and the polishing composition and the object to be polished, and the chemical action of the polishing composition on the object to be polished. As the polishing pad system, non-woven fabric, polyaminocarboxylic acid can be used without particular limitation. A porous body such as an ester or a Swedish phthalocyanine. Preferably, the polishing pad is subjected to a process of accumulating the polishing liquid.

The polishing conditions in the polishing method of the present invention include a polishing load, a number of rotations of the plate, a number of rotations of the carrier, a flow rate of the polishing composition, and a polishing time. The polishing conditions are not particularly limited, but for example, for the polishing load, it is preferably 0.1 psi or more, 10 psi or less, more preferably 0.5 psi or more, 8.0 psi or less, still more preferably 1.0 psi per unit area of the substrate. Above, below 6.0 psi. In general, the higher the load, the higher the friction caused by the abrasive grains, and the mechanical processing force will increase, so the polishing speed will increase. If it is in this range, sufficient polishing speed can be exhibited, and defects such as breakage of the substrate due to the load or damage to the surface can be suppressed. The number of rotations of the plate and the number of rotations of the carrier are preferably from 10 to 500 rpm. The supply amount of the polishing composition may be any amount that can cover the entire amount of the substrate of the material to be polished, and may be adjusted in accordance with conditions such as the size of the substrate.

The polishing composition of the present invention may be of a one-liquid type or a multi-liquid type which is previously prepared into a two-liquid type. Moreover, the polishing composition of the present invention can be adjusted by diluting the stock solution of the polishing composition to, for example, 10 times or more by using a diluent such as water.

[Examples]

The present invention will be described in more detail by way of the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following embodiments.

(Examples 1 to 13 and Comparative Examples 1 to 7)

The abrasive grains (colloidal cerium oxide shown in Table 1) and the alkylene oxide-containing compound were added to the water as a solvent at a concentration shown in Table 1, and the compounds shown in Table 1 were added at a concentration shown in Table 1 as a solvent. The additive was stirred and mixed to obtain a polishing composition (mixing temperature: about 25 ° C, mixing time: about 10 minutes). Further, the pH of the polishing composition was adjusted with the additive 1 shown in Table 1, and confirmed by a pH meter.

Here, the polishing conditions and the object to be polished are as follows.

(grinding conditions)

Grinding machine: CMP single-side grinding machine for 200mm wafer

Pad: Polyurethane pad

Pressure: 3 psi (about 20.7 kPa)

Number of rotations: 90rpm

Flow rate of the polishing composition: 130 ml/min

Grinding time: 1 minute

Grinding object: 200mm wafer (Poly-Si, SiN, TEOS)

Poly-Si: 5,000 Å thick by low pressure chemical vapor growth (LPCVD)

SiN: 3500Å thick by low pressure chemical vapor growth (LPCVD)

TEOS: manufactured by physical vapor phase growth (PVD) Thickness 10000Å

The polishing rate was evaluated by determining the thickness before and after the polishing by the light interference type film thickness measuring device, and dividing the difference by the polishing time.

An 8-inch Poly-Si pattern wafer having the following structure was polished for the step difference, and AFM (Atomic Force Microscope) was used to measure the portion of the line and space with a line and space of 0.25 μm/0.25 μm. The step of the Poly-Si layer.

<<8吋 Poly-Si Pattern Wafer>>

specification

Tier 1: P-TEOS thickness 1000Å

Layer 2: Poly-Si thickness 500Å

Layer 3: 854 pattern + etching

Layer 4: SiN thickness is 1000Å.

Further, the measurement conditions of the weight average molecular weight of the polyoxyalkylene-containing compound are as follows.

GPC device: manufactured by Shimadzu Corporation

Type: Prominence+ELSD Detector (ELSD-LTII)

Pipe column: VP-ODS (made by Shimadzu Corporation)

Mobile phase A: MeOH

B: 1% aqueous solution of acetic acid

Flow rate: 1ml/min

Detector: ELSD temp.40°C, Gain 8, N ₂ GAS 350kPa

Oven temperature: 40 ° C

Injection amount: 40 μl.

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

As is apparent from the results shown in Table 1, it is understood that the polishing compositions of Examples 1 to 13 of the present invention are compared with polycrystalline germanium (Poly-Si) and tetraethoxysilane (TEOS). It can grind tantalum nitride (SiN) with higher selectivity. Further, it is also known that the occurrence of the step can be sufficiently suppressed.

On the other hand, the polishing composition (Comparative Example 1) in which the organic compound was not added, and the polishing composition (Comparative Examples 2 and 3) in which an organic compound other than the polyoxyalkylene-containing compound was added, and only one type was added. In the polishing composition of the polyoxyalkylene compound (Comparative Examples 4 to 6), a highly selective polishing rate ratio could not be obtained, and the occurrence of a step was not sufficiently suppressed. Further, in the polishing composition of Comparative Example 7 having a pH of more than 7, the polishing rate of the Si-N as the object to be polished was lowered, and the polishing rate of the Poly-Si was too high, so that the evaluation of the step could not be performed.

In addition, the present invention is based on Japanese Patent Application No. 2014-200423, filed on Sep. 30, 2014, and Japanese Patent Application No. 2015-59669, filed on Mar. All references.

Claims (8)

A polishing composition comprising: a cerium oxide having an organic acid immobilized on a surface thereof, and a polyoxyalkylene-containing compound obtained by gel permeation chromatography (GPC) for the polyoxyalkylene-containing compound The molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) has two or more peaks and a pH of 7 or less. The polishing composition according to claim 1, wherein the organic acid is a sulfonic acid or a carboxylic acid. The polishing composition according to claim 1 or 2, wherein the polyoxyalkylene-containing compound is one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. The polishing composition according to any one of claims 1 to 3, wherein the cerium oxide having an organic acid immobilized on the surface thereof has an average primary particle diameter of 5 to 50 nm. The polishing composition according to any one of claims 1 to 4, wherein the cerium oxide having an organic acid fixed to the surface thereof has an average secondary particle diameter of 10 to 100 nm. A method for producing a polishing composition comprising the steps of: ceria having an organic acid immobilized on a surface thereof and a weight average molecular weight (in terms of polyethylene glycol) obtained by gel permeation chromatography (GPC) The molecular weight distribution is a mixture of polyoxyalkylene-containing compounds having a peak of 2 or more The step of combining, and the step of adjusting the pH to 7 or less. A polishing method for polishing an object to be polished by using the polishing composition according to any one of claims 1 to 5 or the polishing composition produced by the production method of claim 6. A method for producing a substrate, comprising the step of polishing the object to be polished by the polishing method of claim 7.