TWI679272B - Polishing composition and polishing method using the same - Google Patents

Abstract

The present invention provides a polishing composition capable of sufficiently suppressing the sag phenomenon in the polishing step and more surely removing the step difference.

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

Description

Polishing composition and polishing method using the 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 manufacturing process of semiconductor devices, with the improvement of the performance of semiconductor devices, it is necessary to have a technology of manufacturing wirings with higher density and high integration. In the manufacturing process of such a semiconductor device, CMP (Chemical Mechanical Polishing) is a necessary process. With the development of miniaturization of semiconductor circuits, the flatness required for the unevenness of patterned wafers has increased, and nanometer-level high flatness is required to be achieved by CMP. Preferably, in order to achieve high smoothness by CMP, the convex portion of the patterned wafer is polished at a high polishing rate, while the concave portion is not polished.

Semiconductor wafers are composed of heterogeneous materials such as polycrystalline silicon that forms circuits, silicon oxide as an insulating material, and silicon nitride to protect the surface of silicon dioxide that is not part of a trench or perforation from damage during etching. Therefore, materials that are relatively soft and easily react with abrasives, such as polycrystalline silicon or silicon oxide, are more likely to cause The degree of scraping is called a depression, and there is a problem that a step difference remains.

Based on these problems, in the polishing step of a pattern wafer made of a material such as hard and chemically stable silicon nitride, it is required to sufficiently remove the step difference.

As a technique for responding to this request, for example, in Japanese Patent Application Laid-Open No. 2012-040671 (equivalent to the specification of U.S. Patent Application Publication No. 2013/146804), a polishing composition is disclosed. The polishing composition, which is polished at a higher speed than polycrystalline silicon and the like, is a polishing composition that lacks chemical reactivity, such as silicon nitride, and contains colloidal silicon dioxide with an organic acid immobilized, and has a pH of 6 or less. .

However, the conventional polishing composition system has a problem that the above-mentioned sag phenomenon cannot be sufficiently suppressed, and the step difference cannot be sufficiently resolved.

Therefore, an object of the present invention is to provide a polishing composition capable of sufficiently suppressing the sag phenomenon in the polishing step and more reliably removing the step.

In order to solve the above-mentioned problems, the present inventors have worked hard to study. As a result, it was found that a compound having a polyoxyalkylene (also referred to as a "polyoxyalkylene-containing compound" in this specification) was used in a molecular weight distribution of a weight-average molecular weight measured by gel permeation chromatography (GPC). The compound having two or more peaks is used in combination with silicon dioxide having an organic acid immobilized on its surface, thereby solving the above-mentioned problems, and the present invention has been completed.

That is, the present invention is a polishing composition, which contains silicon dioxide and a polyoxyalkylene-containing compound having an organic acid immobilized on a surface thereof, and gel permeation chromatography method for the aforementioned polyoxyalkylene-containing compound ( The molecular weight distribution of the weight average molecular weight (polyethylene glycol conversion) obtained by GPC) has two or more peaks, and the pH is 7 or less.

Hereinafter, the present invention will be described.

<Polishing composition>

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

Although the dent phenomenon in the polishing step can be sufficiently suppressed by using the polishing composition of the present invention, and the detailed reason for more accurately removing the step is not clear, it is presumed to be due to the following mechanism.

That is, as disclosed in Japanese Patent Application Laid-Open No. 2012-040671 (equivalent to the specification of U.S. Patent Application Publication No. 2013/146804) as a "water-soluble polymer", it can be known that it can also be used in polishing compositions. Polyoxyalkylene-containing compounds such as polyethylene glycol (PEG) are added. Speculative If these compounds are used, the surface of the object to be polished, such as polycrystalline silicon, is adsorbed by the action of hydrogen bonding and the like, and the surface of the object to be polished is protected from the mechanical action caused by the abrasive particles. The polishing rate of the object to be polished by the polishing composition is controlled. Here, it can be assumed that, as in the present invention, since the polishing composition contains a polyoxyalkylene-containing compound such as having a molecular weight distribution having two or more peaks, a compound having a small molecular weight will be as if buried. Further, it is adsorbed on a gap where a compound having a large molecular weight is adsorbed. 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 difference can be further exerted.

Furthermore, when the material to be polished is polished using the polishing composition of the present invention, it is possible to maintain or increase the polishing speed of SiN as an object to be polished, and further suppress the polishing with polycrystalline silicon or TEOS and the like. The effect of the polishing speed of the layers of different materials of the object. The material to be polished contains silicon nitride (SiN) as the object to be polished, and contains polycrystalline silicon or tetraethyl orthosilicate (TEOS) as the inclusion and polishing. Layers of different materials for the object. Although the polishing speed of SiN is actually 50 Å / min or more during polishing and polishing, and 100 Å / min or more during pattern polishing, when using the polishing composition of the present invention, it becomes possible to maintain or improve such SiN polishing. Speed, and sufficiently suppresses the sag phenomenon in the polishing step, so that the step difference can be removed more reliably.

In addition, since the aforementioned mechanism is obtained by speculation, the present invention is not limited in any way by the aforementioned mechanism. Hereinafter, the structure of the polishing composition which concerns on one aspect of this invention is demonstrated in detail.

[Silicon dioxide with an organic acid fixed on the surface]

The "silica dioxide having an organic acid immobilized on the surface" contained in the polishing composition of the present invention is silicon dioxide having an organic acid chemically bonded to the surface used as abrasive particles. The aforementioned silica includes fumed silica or colloidal silica, but colloidal silica is particularly preferred. Although the said organic acid is not specifically limited, A sulfonic acid, a carboxylic acid, a phosphoric acid, etc. are mentioned, A sulfonic acid or a carboxylic acid is preferable. In addition, the surface of the "silica dioxide having an organic acid immobilized on the surface" contained in the polishing composition of the present invention is immobilized from the above by covalent bonding (via a connection structure according to circumstances). Acidic groups of organic acids (for example, sulfo, carboxyl, phosphate, etc.).

Silicon dioxide based on which an organic acid is fixed on the surface may be a synthetic product or a commercially available product. Moreover, the silicon dioxide system in which an organic acid is fixed on the surface may be used alone, or two or more kinds may be used in combination.

The method for introducing these organic acids onto the surface of silicon dioxide is not particularly limited. In addition to a method of introducing the organic acid on the surface of silicon dioxide in a state such as a mercapto group or an alkyl group, and then oxidizing it to a sulfonic acid or a carboxylic acid, A method in which a protective group is bonded to the surface of silicon dioxide in a state in which a protective group is bonded to an acidic group derived from the organic acid, and then the protective group is removed. In addition, the compound used when the organic acid is introduced on the surface of the silicon dioxide preferably includes a functional group having at least one functional group capable of becoming an organic acid group and further used for bonding with a hydroxyl group on the surface of the silicon dioxide. A functional group, a functional group introduced to control hydrophobicity / hydrophilicity, a functional group introduced to control the volumetric expansion degree, and the like.

As a specific synthetic method of silicon dioxide having an organic acid fixed on the surface, if a sulfonic acid, which is one of the organic acids, is fixed on the surface of silicon dioxide, for example, "Sulfonic acid-functionalized silica through quantitative "oxidation of thiol groups", Chem. Commun. 246-247 (2003). Specifically, a thiol group-containing silane coupling agent such as 3-mercaptopropyltrimethoxysilane is coupled to silicon dioxide, and then the thiol group is oxidized with hydrogen peroxide to obtain an immobilized surface. Sulfonic acid silicon dioxide. Alternatively, if the carboxylic acid is fixed on the surface of silicon dioxide, it can be based on, 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, 3,228-229 (2000). Specifically, by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to silicon dioxide and then irradiating the light, silicon dioxide having a carboxylic acid immobilized on the surface can be obtained.

The average primary particle diameter of the silicon dioxide in 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, and even more preferably 10 nm or more. It has the advantage that as the average primary particle diameter of silicon dioxide having an organic acid fixed on its surface increases, the polishing rate of the polishing object caused by the polishing composition is increased.

The average primary particle diameter of the silicon dioxide in 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, and even more preferably 40 nm or less. Has the following advantages: With the surface The smaller the average primary particle diameter of the silica to which the organic acid is fixed, the more it is possible to suppress the occurrence of scratches on the surface of the object to be polished after polishing with the polishing composition. The value of the average primary particle diameter of silicon dioxide having an organic acid immobilized on the surface can be calculated, for example, from the specific surface area of the silicon dioxide having an organic acid immobilized on the surface, as measured by the BET method.

The average secondary particle diameter of the silicon dioxide in 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, and even more preferably 20 nm or more. It has the advantage that as the average secondary particle diameter of the silicon dioxide having the organic acid fixed on the surface increases, the polishing speed of the polishing object caused by the polishing composition is increased.

The average secondary particle diameter of the silica in 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, and even more preferably 80 nm or less. This has the advantage that the smaller the average secondary particle diameter of the silicon dioxide to which the organic acid is fixed on the surface, the more it is possible to suppress the occurrence of scratches on the surface of the object to be polished after polishing with the polishing composition. The value of the average secondary particle diameter of the silicon dioxide can be calculated, for example, from the specific surface area of the silicon dioxide measured using a laser light scattering method.

The content of the silicon dioxide in which the organic acid is fixed on the surface in the polishing composition is preferably 0.0005 mass% or more, more preferably 0.001 mass% or more, and even more preferably 0.005 mass% or more. It has the advantage that as the content of silicon dioxide having an organic acid fixed on the surface increases, the polishing speed of the polishing object caused by the polishing composition is increased.

Organic acid is fixed on the surface in the polishing composition The content of silicon oxide is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less. It has the following advantages: As the content of silicon dioxide with an organic acid fixed on the surface decreases, the friction with the material to be polished decreases. For example, when silicon nitride (SiN) is used as the object to be polished, it can be more suppressed. The polishing rate of a layer containing a material different from the object to be polished, such as polycrystalline silicon or TEOS.

In addition, in the present invention, although "silica dioxide having an organic acid immobilized on its surface" must be used as the abrasive grain, it may be used in combination with silica without an organic acid immobilized on its surface depending on the situation. However, the content of "silica dioxide with 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, and even more preferably Above 90% by mass, particularly preferably above 95% by mass, and most preferably at 100% by mass. In addition, if only "silicon dioxide having no organic acid fixed on the surface" is used as the abrasive grains, the defect performance due to agglomerates may be deteriorated, which is not preferable.

[Polyoxyalkylene-containing compound]

The "polyoxyalkylene-containing compound" contained in the polishing composition of the present invention is an organic compound containing a polyoxyalkylene. The "polyoxyalkylene-containing compound" may be a compound obtained by substituting or polymerizing a part of the functional groups of the compound having a polyoxyalkylene. These systems can be used alone or in combination of two or more.

Specific examples of the polyoxyalkylene include polyoxyethylene, polyoxypropylene, and block or random bonding of oxyethylene and oxypropylene. The resulting polyoxyalkylene group further includes a oxyoxybutenyl group and the like, which are further bonded in a block or random manner to the aforementioned polyoxyethylene group, polyoxypropylene group, and polyoxyalkylene group.

Specific examples of the compound in which the terminal of the polyoxyalkylene is a hydroxyl group include various addition amounts of polyalkylene glycol derivatives such as polyethylene glycol, polypropylene glycol, and polybutylene glycol, and PRONON (registered trademark) 102 Block polymers represented by the PRONON (registered trademark) series such as PRONON (registered trademark) 201, etc. (above, made by Nippon Oil Co., Ltd.), UNIOL (registered trademark) DA-400, UNIOL (registered trademark) DB-400 , Bisphenol A derivatives such as UNIOL (registered trademark) DB-530 (above, manufactured by Nippon Oil Co., Ltd.) and the like.

Specific examples of the compound having an ether group at the end of polyoxyalkylene include various polyalkylene glycol alkyl ethers such as polyethylene glycol oleyl ether and polyethylene glycol dimethyl ether.

Specific examples of the compound in which the terminal of the polyoxyalkylene is an ester group include polyalkylene glycol alkyl groups such as polyethylene glycol monooctyl ester, polypropylene glycol monostearyl ester, and polypropylene glycol distearyl ester. Esters, etc.

Specific examples of the compound whose polyoxyalkylene has an allyl end are UNIOX (registered trademark) PKA-5006, UNIOL (registered trademark) PKA-5014, UNIOL (registered trademark) PKA-5017 (above, Nippon Oil Co., Ltd.) and other polyalkylene glycol allyl ethers.

Specific examples of the compound whose polyoxyalkylene terminal is a (meth) acryl group are: BLEMMER (registered trademark) PP series, BLEMMER (registered trademark) PME series, BLEMMER (registered trademark) Standard) PDE series (above, manufactured by Nippon Oil Co., Ltd.) and other polyalkylene glycol (meth) acrylates.

Among them, the polyoxyalkylene-containing compound is preferably one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, and polybutylene glycol, and more preferably polyethylene glycol.

In the polishing composition of the present invention, the molecular weight distribution of the weight average molecular weight (polyethylene glycol conversion) obtained by gel permeation chromatography (GPC) of the polyoxyalkylene-containing compound described above has two molecular weight distributions. The points of the above peaks are characteristic. Here, the term "having two or more peaks" means that the graph of the molecular weight distribution of the polyoxyalkylene-containing compound by GPC has two or more maximum values. Typically, as described in the production method of the polishing composition described later, the 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 conditions of "having two or more peaks" as described above.

In the case where the molecular weight distribution of the weight-average molecular weight (in terms of polyethylene glycol) measured by GPC for a polyoxyalkylene-containing compound has two or more peaks, it corresponds to one of the peaks corresponding to the two or more peaks. Among the weight average molecular weights, the weight average molecular weights of at least two peaks are preferably 1.1 times or more different from each other, more preferably 1.3 times or more different, and even more preferably 1.5 times or more different. With this configuration, the effects of the present invention can be fully exhibited.

When the molecular weight distribution has two peaks, the weight average molecular weight of the peak with 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 with a larger weight-average molecular weight is preferably 300 to 1,000,000, and more preferably 300 to 100,000.

Furthermore, in a case where the molecular weight distribution system has three or more peaks, the weight average molecular weight of a peak having a smaller weight average molecular weight among any two peak molecular weights selected from the three or more peaks is preferably 100 to 2000, more preferably 100 ~ 1000. In addition, among any two peak molecular weights selected from the three or more peaks, the weight average molecular weight of the peak having a larger weight average molecular weight is preferably 300 to 1,000,000, and more preferably 300 to 100,000.

The weight average molecular weight of the polyoxyalkylene-containing compound can be measured specifically 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, and still more preferably 0.001% by mass or more. 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, and still more preferably 20% by mass or less. If it is such a range, the effect of this invention can fully be exhibited.

[additive]

The polishing composition of the present invention may also contain additives. 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 additives include formic acid, Acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, heptaic acid, stearic acid, oleic acid, linoleic acid, Sour oleic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, willow Acid, gallic acid, tartaric acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acids, anthranilic acid Carboxylic acids such as nitrocarboxylic acids, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, 2-isethionic acid, taurine, etc. Sulfonic acid; 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, etc .; imines Diacetic acid, nitrogen triacetic acid, ethylene glycol triamine pentaacetic acid, ethylene diamine tetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylene diamine-N, N, N ', N'-tetra Methylsulfonate , Trans-cyclohexanediamine tetraacetic acid, 1,2-diaminopropane tetraacetic 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-phosphoninobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylene- 1,1-diphosphonic acid, N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid, 1,2-dihydroxybenzene-4,6-disulfonic acid, poly Chelating agents such as amines, polyphosphonic acids, polyaminocarboxylic acids, polyaminophosphonic acids, etc., amines such as aliphatic amines, aromatic amines, organic bases such as quaternary ammonium hydroxide, potassium hydroxide (KOH) And other alkali metal hydroxides, Group 2 element hydroxides, and ammonia. These additives may be used alone or in combination of two or more.

Among these additives, citric acid, phosphoric acid, and amines are preferred. Diacetic acid, anthranilic 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 long as it is the pH of the polishing composition described below. In the case where an additive having both a function of adjusting the pH and a function of increasing the polishing speed of the object to be polished is used in such an amount, the effect of increasing the polishing speed of the object to be polished can also be exhibited.

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

[PH of polishing composition]

The pH of the polishing composition of the present invention is 7 or less. If the pH value is greater than 7, the positive charge on the surface of the object to be polished will decrease. Therefore, abrasive particles with a negative surface charge (silica dioxide with an organic acid fixed on the surface) will be used to grind the object at high speed. One thing will become difficult. From the viewpoint of polishing the object to be polished at a sufficient polishing rate with the polishing composition, 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 safety, the pH value of the polishing composition is preferably 1 or more, and more preferably 1.5 or more.

[Dispersion 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 preferable to use water with high purity as much as possible. Specifically, it is preferable to remove pure ions, ultrapure water, or distilled water after removing the foreign ions through a filter after removing the impurity ions with an ion exchange resin. Further, as a dispersion medium or a solvent, an organic solvent or the like may be further included for the purpose of controlling the dispersibility of other components of the polishing composition.

[Other ingredients]

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

[Oxidant]

An oxidizing agent that can be added to the polishing composition has the function of oxidizing the surface of the polishing object, thereby increasing the polishing rate of the polishing object caused by the polishing composition.

Examples of usable oxidants include: hydrogen peroxide, sodium peroxide, barium peroxide, organic oxidants, ozone water, silver (II) salt, iron (III) salt, permanganic acid, chromic acid, dichromic acid, peroxide Dioxosulfuric acid, peroxyphosphoric acid, peroxysulfuric acid, peroxyboronic acid, peroxyformic acid, peroxyacetic acid, peroxybenzene Formic acid, peroxyphthalic acid, hypochlorous acid, hypobromous acid, hypoiodic acid, chloric acid, chlorous acid, perchloric acid, bromic acid, iodic acid, periodic acid, persulfuric acid, dichloroisotrimer Cyanic acid and such salts. These oxidizing agents can be used alone or in combination of two or more. 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, and even more preferably 3 g / L or more. As the content of the oxidant increases, the polishing rate of the object to be polished due to the polishing composition increases.

The content of the oxidizing agent in the polishing composition is preferably 200 g / L or less, more preferably 100 g / L or less, and still more preferably 40 g / L or less. As the content of the oxidant decreases, in addition to suppressing the material cost of the polishing composition, it can also reduce the processing of the polishing composition after polishing, that is, the load of waste liquid treatment. In addition, it is possible to reduce the fear of causing excessive oxidation of the surface of the object to be polished due to the oxidant.

[Preservative and mildew inhibitor]

Examples of the antiseptic and antifungal agent that can be added to the polishing composition of the present invention include 2-methyl-4-isothiazolin-3-one or 5-chloro-2-methyl-4 -Isothiazoline-based preservatives such as isothiazoline-3-one, parabens, and phenoxyethanol. These preservatives and antifungal agents can 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 particles. Examples of the water-soluble polymer system include hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, and methyl cellulose. , Ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose and other cellulose derivatives; poly (N-fluorenylalkyleneimine) and other imine derivatives; polyvinyl alcohol; denatured (cationic (Denatured, or non-ionic denatured) polyvinyl alcohol; polyvinylpyrrolidone; polyvinylcaprolactam; polyoxyalkylene such as polyoxyethylene; and copolymers containing these constituent units. These water-soluble polymers can be used alone or in combination of two or more.

[Manufacturing method of polishing composition]

The manufacturing method of the polishing composition of the present invention is not particularly limited. For example, a method including the following steps can be adopted: silicon dioxide having an organic acid fixed on the surface thereof, and a method obtained by gel permeation chromatography (GPC). 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, water and other components may be further stirred and mixed as needed. The details of each component added are as described above.

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

Although the temperature at which the components are mixed is not particularly limited, it is preferably 10 to 40 ° C, and heating may be performed to increase the dissolution rate.

[Object to be polished]

The object to be polished in the present invention is not particularly limited, and examples thereof include nitrides such as silicon nitride, alloys such as aluminum-magnesium, and silicon-germanium, or materials including such composite materials. Examples of the polishing target system including a silicon-containing material include elemental silicon and silicon compounds. Examples of the simple silicon system include single crystalline silicon, polycrystalline silicon (polycrystalline silicon, Poly-Si), and amorphous silicon. Examples of the silicon compound system include silicon nitride, silicon oxide, silicon carbide, and SiGe. The silicon compound film includes a low-dielectric film having a relative dielectric constant of 3 or less. It is particularly preferable that the object to be polished contains polycrystalline silicon.

The object to be polished may include a metal. The metal is not particularly limited, and examples thereof include tungsten, copper, aluminum, rhenium, cobalt, nickel, titanium, tantalum, titanium, cobalt, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium, germanium, and the like. These metal systems may be contained in the form of an alloy or a metal compound. When the object to be polished includes a metal, copper is preferred. These objects to be polished may be used alone or in combination of two or more. 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 structure, each layer system may include the same material or different materials.

Furthermore, the object to be polished of the present invention may have a layer between the object to be polished as described above and a material different from the material to be polished. For example, when the object to be polished is a silicon compound such as silicon nitride (SiN), examples of materials different from the object to be polished include polycrystalline silicon, single crystalline silicon, and tetraethyl orthosilicate ( TEOS) and so on. These materials may be used alone or in combination of two or more.

[Polishing method using polishing composition]

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

When the object to be polished is polished using the polishing composition of the present invention, it can be performed using an apparatus or conditions used in ordinary polishing. A general polishing apparatus is a single-sided polishing apparatus or a double-sided polishing apparatus. In a single-side polishing apparatus, a substrate is held by a holder called a carrier, and while a polishing composition is supplied from above, a fixed plate to which a polishing pad is attached is pressed against the opposite surface of the substrate so that The platen is rotated to polish one side of the material to be polished. At this time, polishing is performed by a physical action caused by friction between the polishing pad and the polishing composition and the object to be polished, and a chemical action caused by the polishing composition on the object to be polished. As the polishing pad system, a non-woven fabric, a polyurethane, or the like may be used without particular limitation. Ester, porous body such as Swedish turnip, etc. Preferably, the polishing pad is subjected to a process for accumulating polishing liquid.

Examples of the polishing conditions in the polishing method of the present invention include a polishing load, a number of rotations of a platen, a number of rotations of a carrier, a flow rate of a polishing composition, and a polishing time. Although these grinding conditions are not particularly limited, for example, for grinding load, it is preferable that each unit area of the substrate is 0.1 psi or more and 10 psi or less, more preferably 0.5 psi or more, 8.0 psi or less, and even more preferably 1.0 psi. Above and below 6.0psi. In general, the higher the load, the higher the friction caused by the abrasive particles, and the mechanical processing power will increase, so the grinding speed will increase. Within this range, sufficient polishing speed can be exhibited, and defects such as damage to the substrate due to load or damage to the surface can be suppressed. The number of rotations of the fixed plate and the number of rotations of the carrier are preferably 10 to 500 rpm. The supply amount of the polishing composition is only required to cover the entire supply of the base plate of the material to be polished, and it may be adjusted according to conditions such as the size of the substrate.

The polishing composition system of the present invention may be a one-liquid type, or a multi-liquid type that is previously made into a two-liquid type. 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.

[Example]

The following examples and comparative examples are used to explain the present invention in more detail. However, the technical scope of the present invention is not limited to the following embodiments.

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

Add abrasive particles (colloidal silicon dioxide shown in Table 1) and alkylene oxide-containing compounds to water as a solvent at the concentrations shown in Table 1, and add the compounds shown in Table 1 at the concentrations shown in Table 1 as The additives were stirred and mixed to obtain a polishing composition (mixing temperature: about 25 ° C, mixing time: about 10 minutes). The pH of the polishing composition was adjusted with Additive 1 shown in Table 1, and confirmed with a pH meter.

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

(Grinding conditions)

Grinder: CMP single-side grinder for 200mm wafers

Pad: Polyurethane pad

Pressure: 3psi (about 20.7kPa)

Fixed plate rotation: 90rpm

Flow rate of polishing composition: 130ml / min

Grinding time: 1 minute

Object to be polished: 200mm wafer (Poly-Si, SiN, TEOS)

Poly-Si: 5000Å thickness manufactured by low pressure chemical vapor growth (LPCVD)

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

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

The polishing speed was evaluated by using a light interference film thickness measuring device to determine the thickness before and after polishing, and dividing the difference by the polishing time.

An 8-inch Poly-Si patterned wafer having the following structure was polished for the step difference, and an AFM (atomic force microscope) was used to measure and measure the part with a line and space of 0.25 μm / 0.25 μm. Poly-Si layer step.

<< 8-inch Poly-Si pattern wafer >>

specification

Layer 1: P-TEOS thickness 1000Å

Layer 2: Poly-Si thickness 500Å

Layer 3: 854 pattern + etching

Layer 4: SiN thickness 1000Å.

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)

Column: VP-ODS (manufactured by Shimadzu Corporation)

Mobile phase A: MeOH

B: 1% aqueous acetic acid solution

Flow: 1ml / min

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

Oven temperature: 40 ° C

Injection volume: 40 μl.

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

As is clear from the results shown in Table 1, it was found that by using the polishing compositions of Examples 1 to 13 of the present invention, it was compared with polycrystalline silicon (Poly-Si) and tetraethoxysilane (TEOS). , Which can more selectively grind silicon nitride (SiN). It can also be seen that the occurrence of step differences can be sufficiently suppressed by this.

On the other hand, to a polishing composition (Comparative Example 1) without adding an organic compound, and a polishing composition (Comparative Examples 2 and 3) to which an organic compound other than the polyoxyalkylene-containing compound was added, only one In the polishing composition of the polyoxyalkylene compound (Comparative Examples 4 to 6), a highly selective polishing speed ratio could not be obtained, and the occurrence of a step difference could not be sufficiently suppressed. Furthermore, in the polishing composition of Comparative Example 7 having a pH exceeding 7, since the polishing rate of SiN, which is an object to be polished, was lowered, the polishing rate of Poly-Si became too high, and thus the step difference could not be evaluated.

In addition, the present invention is based on Japanese Patent Application No. 2014-200423 filed on September 30, 2014 and Japanese Patent Application No. 2015-59669 filed on March 23, 2015, and the disclosure thereof is by reference All references.

Claims (8)

A polishing composition comprising: silicon dioxide having an organic acid immobilized on a surface thereof, and a polyoxyalkylene-containing compound, and obtained by gel permeation chromatography (GPC) for the aforementioned polyoxyalkylene-containing compound. The molecular weight distribution of the weight average molecular weight (in terms of polyethylene glycol) has two or more peaks and the pH is 7 or less. When the molecular weight distribution has two peaks, the weight average of the smaller peaks of the weight average molecular weight The molecular weight is 100 to 2000. In the case where 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 with a smaller weight-average molecular weight is 100 ~ 2000. 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 polybutanediol. The polishing composition according to claim 1 or 2, wherein the average primary particle diameter of the silicon dioxide having the organic acid immobilized on the surface is 5 to 50 nm. The polishing composition according to claim 1 or 2, wherein the average secondary particle diameter of the silicon dioxide having the organic acid fixed on the surface is 10 to 100 nm. A method for manufacturing a polishing composition, comprising the steps of: fixing silicon dioxide having an organic acid on its surface; and weight average molecular weight (polyethylene glycol conversion) obtained by gel permeation chromatography (GPC). The molecular weight distribution 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. When the molecular weight distribution has two peaks, the weight average molecular weight is smaller. The weight average molecular weight of the peak is 100 to 2000. In the case where the molecular weight distribution system has three or more peaks, among any two peak molecular weights selected from the three or more peaks, the peak of the smaller weight average molecular weight is The weight average molecular weight is 100 ~ 2000. A polishing method for polishing an object to be polished using the polishing composition according to any one of claims 1 to 5 or the polishing composition manufactured by the manufacturing method according to claim 6. A manufacturing method of a substrate includes a step of polishing an object to be polished by the polishing method of claim 7.