Grinding composition

Abstract

The present invention provides an abrasive composition that can polish carbon films at a high polishing speed. [Solution] An abrasive composition comprising abrasive particles and a nonionic surfactant, used for polishing objects containing a carbon film.

Description

Technical Field

[0001] The present invention relates to a polishing composition.

Background Art

[0002] In recent years, with the multilayer wiring of the semiconductor substrate surface, when manufacturing devices, a so-called Chemical Mechanical Polishing (CMP) technique that polishes and planarizes the semiconductor substrate is used. CMP is a method of planarizing the surface of an object to be polished (workpiece to be polished), such as a semiconductor substrate, using a polishing composition.

[0003] In the field of CMP technology, studies have been continuously conducted to achieve desired effects by polishing.

[0004] Patent Document 1 discloses that a polishing composition containing inorganic particles having a specific particle size distribution and an organic acid immobilized on the surface and an acidic compound can polish both silicon oxide and silicon nitride at a high polishing rate on a substrate containing silicon oxide and silicon nitride. Patent Document 1 also discloses that the object to be polished contains a carbon film.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to the technique described in Patent Document 1, the silicon oxide film and the silicon nitride film can be polished at a high polishing rate. However, there is room for improvement in the polishing rate of the carbon film.

[0007] Therefore, the present invention aims to provide a polishing composition that can polish carbon films at a high polishing speed. [Means for solving the problem]

[0008] To solve the above problems, the inventors conducted extensive research. As a result, they discovered that the above problems could be solved by an abrasive composition containing abrasive particles and a nonionic surfactant, used for polishing objects containing a carbon film, and thus completed the present invention. [Effects of the Invention]

[0009] The present invention provides an abrasive composition that can polish a carbon film at a high polishing speed. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below and can be modified in various ways within the scope of the claims. The embodiments described herein can be combined in any way to form other embodiments. Unless otherwise specified herein, operations and measurements of physical properties, etc., are performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40% RH to 50% RH.

[0011] <Polishing composition> One aspect of the present invention relates to an abrasive composition comprising abrasive particles and a nonionic surfactant, used for polishing objects containing a carbon film. The abrasive composition according to the present invention can polish carbon films at a high polishing rate.

[0012] [Abrasive grains] The polishing composition according to the present invention contains abrasive grains.

[0013] The type of abrasive grain is not particularly limited, and examples include metal oxides such as silica, alumina, zirconia, and titania. The abrasive grain may be used alone or in combination of two or more types. Furthermore, the abrasive grain may be a commercially available product or a synthetic product.

[0014] In one embodiment, the abrasive grains contain silica, preferably colloidal silica. Examples of methods for producing colloidal silica include the sodium silicate method and the sol-gel method. Colloidal silica produced by either method is suitable for use as the abrasive grains of the present invention. However, from the viewpoint of reducing metal impurities, colloidal silica produced by the sol-gel method, which can be produced with high purity, is preferred.

[0015] Colloidal silica can be produced by the sol-gel method using conventionally known techniques. Specifically, colloidal silica can be obtained by using a hydrolyzable silicon compound (e.g., alkoxysilane or its derivatives) as a raw material and carrying out a hydrolysis-condensation reaction.

[0016] In preferred embodiments, the abrasive grains include anionically modified colloidal silica (colloidal silica having anionic groups). Examples of anionically modified colloidal silica include colloidal silica in which anionic groups such as carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and aluminic acid groups are immobilized on the surface.

[0017] The method for producing anionically modified colloidal silica is not particularly limited, and one example is a method of reacting colloidal silica with a silane coupling agent having anionic groups at its terminals.

[0018] For example, if you want to immobilize sulfonic acid groups on colloidal silica, you can do so by the method described in “Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups”, Chem.Commun. 246-247 (2003). Specifically, by coupling a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, to colloidal silica and then oxidizing the thiol group with hydrogen peroxide, you can obtain colloidal silica with sulfonic acid groups immobilized on its surface (sulfonic acid-modified colloidal silica).

[0019] If the goal is to immobilize a carboxyl group on colloidal silica, this can be done, for example, by the method described in “Novel Silane Coupling Agents Containing a Photolabile 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 colloidal silica and then irradiating it with light, colloidal silica with immobilized carboxyl groups on its surface (carboxylic acid-modified colloidal silica) can be obtained.

[0020] The average primary particle diameter of abrasive grains is not particularly limited, but is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. The average primary particle diameter of abrasive grains is not particularly limited, but is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. Preferred average primary particle diameters of abrasive grains include, for example, 1 nm to 100 nm, 3 nm to 50 nm, and 5 nm to 30 nm. However, the average primary particle diameter of abrasive grains is not limited to these ranges. When the abrasive grains are anionically modified colloidal silica, the preferred range of average primary particle diameters for anionically modified colloidal silica is the same as the preferred range of average primary particle diameters of abrasive grains listed above. The average primary particle diameter of abrasive grains can be calculated based on the specific surface area (SA) of the abrasive grains calculated by the BET method and the density of the abrasive grains. More specifically, the average primary particle diameter of abrasive grains can be measured and calculated by the method described in the examples.

[0021] The average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 25 nm or more. Within this range, the resistance during polishing is reduced, and stable polishing becomes possible. The average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. Within this range, the amount of material scraped off the workpiece is improved, and the polishing speed is further improved. Examples of preferred average secondary particle diameters of abrasive grains include 15 nm to 500 nm, 20 nm to 400 nm, and 25 nm to 300 nm. However, the average secondary particle diameter of the abrasive grains is not limited to these ranges. When the abrasive grains are anionically modified colloidal silica, the preferred range of average secondary particle diameter for anionically modified colloidal silica is the same as the preferred range of average secondary particle diameter for abrasive grains mentioned above. The average secondary particle diameter of abrasive grains can be measured as the volume-average particle diameter (volume-based arithmetic mean diameter; Mv) by dynamic light scattering. More specifically, the average secondary particle diameter of abrasive grains can be measured by the method described in the examples.

[0022] The ratio of the average secondary particle diameter to the average primary particle diameter of the abrasive grains (average secondary particle diameter / average primary particle diameter) (hereinafter, the "ratio of the average secondary particle diameter to the average primary particle diameter" is also referred to as the "average degree of aggregation"). Although not particularly limited, it is preferably greater than 1.0, more preferably 1.1 or more, and even more preferably 1.2 or more. The average degree of aggregation of the abrasive grains is not particularly limited, but is preferably 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less. Preferred average degrees of aggregation of the abrasive grains include, for example, greater than 1.0 and 4.0 or less, 1.1 or more and 3.5 or less, 1.2 or more and 3.0 or less, etc. However, the average degree of aggregation of the abrasive grains is not limited to these ranges. When the abrasive grains contain anionic modified colloidal silica, the preferred range of the average degree of aggregation of the anionic modified colloidal silica is also the same as the preferred range of the average degree of aggregation of the abrasive grains mentioned above. The average degree of aggregation of the abrasive grains can be calculated by dividing the value of the average secondary particle diameter of the abrasive grains by the value of the average primary particle diameter of the abrasive grains (value of the average secondary particle diameter of the abrasive grains / value of the average primary particle diameter of the abrasive grains).

[0023] The shape of the abrasive grains (preferably anionic modified colloidal silica) is not particularly limited and may be spherical (hereinafter also referred to as spherical) or non-spherical. Specific examples of non-spherical shapes include polyhedral shapes such as triangular prisms and square prisms, cylindrical shapes, barrel shapes where the central part of the cylinder bulges more than the ends, donut shapes where the central part of the disk penetrates, plate shapes, so-called cocoon shapes (cocoon-shaped) with a constriction in the central part, so-called aggregated spherical shapes where multiple particles are integrated, so-called sugar ball shapes with multiple protrusions on the surface, rugby ball shapes, etc. There are various shapes and are not particularly limited.

[0024] The shape and size (average primary particle diameter, average secondary particle diameter, average degree of aggregation, etc.) of the abrasive grains can be appropriately controlled, for example, by the selection of the manufacturing method of the abrasive grains, etc. However, the control methods of the shape and size of the abrasive grains are not limited to these respectively.

[0025] The content (concentration) of abrasive grains (preferably anionically modified colloidal silica) in the polishing composition is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and particularly preferably 0.3% by mass or more, relative to the total mass of the polishing composition. The content of abrasive grains (preferably anionically modified colloidal silica) in the polishing composition is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less, relative to the total mass of the polishing composition. Within the above range, the polishing speed when polishing a specific object to be polished is further improved. Also, within the above range, the selectivity ratio between specific objects to be polished may be further improved. The preferred content of abrasive grains (preferably anionically modified colloidal silica) in the polishing composition is not particularly limited, but examples include 0.01% to 10% by mass, 0.05% to 5% by mass, 0.1% to 2% by mass, and 0.3% to 1% by mass, relative to the total mass of the polishing composition. However, the content of abrasive grains in the polishing composition is not limited to these ranges.

[0026] [Nonionic surfactants] The polishing composition according to the present invention contains a nonionic surfactant. The nonionic surfactant may be used alone or in combination of two or more. The nonionic surfactant may be a commercially available product or a synthetic product.

[0027] Nonionic surfactants can adsorb onto the hydrophobic surface of a carbon film, making the carbon film surface hydrophilic. Because the hydrophilic carbon film surface interacts with abrasive particles (e.g., anionically modified colloidal silica) more frequently, it is believed that the polishing speed of the carbon film can be improved.

[0028] Examples of nonionic surfactants include alkyl betaines, alkylamine oxides, polyoxyalkylene glycols, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyalkylene fatty acid esters, polyoxyalkylene alkylamines, and alkyl alkanolamides. From the viewpoint of being able to better exhibit the effects of the present invention, the nonionic surfactant is preferably a compound having a polyoxyalkylene glycol structure, such as polyoxyalkylene glycol or polyoxyalkylene alkyl ether (hereinafter also referred to as "polyoxyalkylene glycol-based compound").

[0029] In preferred embodiments, the nonionic surfactant includes a compound having a polyoxyalkylene glycol structure. Examples of compounds having a polyoxyalkylene glycol structure include oxyalkylene homopolymers, oxyalkylene copolymers, and polyoxyalkylene alkyl ethers.

[0030] The oxyalkylene homopolymers and oxyalkylene copolymers are not particularly limited, but examples include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol random copolymer, polyethylene glycol-polytetramethylene glycol random copolymer, polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol block copolymer, polypropylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, and the like.

[0031] In a more preferred embodiment, the nonionic surfactant includes a compound represented by the following formula 1 as a polyoxyalkylene alkyl ether.

[0032] [ka]

[0033] In formula 1, X is an alkylene group having 2 or 3 carbon atoms, m is an integer between 4 and 14, and n is an integer between 3 and 25.

[0034] In formula 1, X is preferably an alkylene group having 2 carbon atoms (i.e., an ethylene group).

[0035] In Equation 1, m is preferably an integer between 5 and 12, and more preferably an integer between 7 and 9.

[0036] In Equation 1, n is preferably an integer between 5 and 15, and more preferably an integer between 5 and 10.

[0037] The compound represented by Formula 1 is preferably at least one selected from the group consisting of polyoxyethylene(5) monooctyl ether, polyoxyethylene(6) monooctyl ether, polyoxyethylene(7) monooctyl ether, polyoxyethylene(8) monooctyl ether, polyoxyethylene(9) monooctyl ether, polyoxyethylene(10) monooctyl ether, polyoxyethylene(5) monononyl ether, polyoxyethylene(6) monononyl ether, polyoxyethylene(7) monononyl ether, polyoxyethylene(8) monononyl ether, polyoxyethylene(9) monononyl ether, polyoxyethylene(10) monononyl ether, polyoxyethylene(5) monodecyl ether, polyoxyethylene(6) monodecyl ether, polyoxyethylene(7) monodecyl ether, polyoxyethylene(8) monodecyl ether, polyoxyethylene(9) monodecyl ether, and polyoxyethylene(10) monodecyl ether.

[0038] The content (concentration) of the nonionic surfactant in the abrasive composition is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, based on the total mass of the abrasive composition. The content (concentration) of the nonionic surfactant in the abrasive composition is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less, based on the total mass of the abrasive composition. The preferred content (concentration) of the nonionic surfactant in the abrasive composition is not particularly limited, but examples include 0.001% by mass or more and 1% by mass or less, 0.005% by mass or more and 0.5% by mass or less, and 0.01% by mass or more and 0.1% by mass or less, based on the total mass of the abrasive composition. In a preferred embodiment, the content (concentration) of the nonionic surfactant in the abrasive composition is 0.01% by mass or more and 0.1% by mass or less, based on the total mass of the abrasive composition. However, the content (concentration) of the nonionic surfactant in the abrasive composition is not limited to these ranges. If the content (concentration) of the nonionic surfactant is within the above range, the effects of the present invention can be more fully realized.

[0039] [Object to be polished] The polishing composition according to the present invention is used for polishing objects containing a carbon film.

[0040] In this specification, the term "carbon film" is not limited to films composed solely of carbon atoms, but also includes carbon films containing atoms other than carbon atoms (such as hydrogen atoms and oxygen atoms).

[0041] Examples of carbon films include spin-on carbon films, amorphous carbon films, diamond-like carbon films, nanocrystalline diamond films, graphene films, SiC films, and SiOC films. The carbon film may be used alone or in combination of two or more types. The carbon film is preferably selected from the group consisting of spin-on carbon films, amorphous carbon films, diamond-like carbon films, nanocrystalline diamond films, and graphene films, and is more preferably a spin-on carbon film.

[0042] The carbon content in the carbon film is defined as 10% or more by mass, 30% or more by mass, 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, 90% or more by mass, 92% or more by mass, 95% or more by mass, 97% or more by mass, 98% or more by mass, and 99% or more by mass, based on the total mass of the carbon film. The amount is preferred in the order of mass% or more. The carbon film may be in a form that is substantially composed of carbon (substantially containing 100% by mass of carbon atoms).

[0043] Carbon films can be formed by methods such as CVD, PVD, and spin coating.

[0044] The object to be polished by the polishing composition according to the present invention may further contain other materials in addition to the carbon film. Examples of other materials include silicon nitride film, silicon oxide, single-crystal silicon, polycrystalline silicon, amorphous silicon, polycrystalline silicon doped with n-type or p-type impurities, amorphous silicon doped with n-type or p-type impurities, titanium nitride, elemental metals, SiGe, and the like.

[0045] Examples of polishing materials containing silicon dioxide include, for example, TEOS (Tetraethyl Orthosilicate) type silicon dioxide films (hereinafter also referred to as "TEOS" or "TEOS film") produced using tetraethyl orthosilicate as a precursor, HDP (High Density Plasma) films, USG (Undoped Silicate Glass) films, PSG (Phosphorus Silicate Glass) films, BPSG (Boron-Phospho Silicate Glass) films, and RTO (Rapid Thermal Oxidation) films.

[0046] Examples of elemental metals include tungsten, copper, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, and osmium.

[0047] [pH] The pH of the polishing composition according to the present invention is not particularly limited. From the viewpoint of being able to better exhibit the effects of the present invention, the pH of the polishing composition according to the present invention is 1.0 or more and 5.0 or less. Preferably, the pH of the polishing composition according to the present invention is 2.0 or more and 4.0 or less, more preferably 2.5 or more and 3.0 or less, and even more preferably 2.7 or more and 3.2 or less. When the pH is within the above range, if anionically modified colloidal silica is used as the abrasive grain, the anionically modified colloidal silica has a negative zeta potential, which has the advantage of excellent dispersion stability.

[0048] The polishing composition according to the present invention may contain a pH adjusting agent to adjust the pH of the polishing composition. The pH adjusting agent may be used alone or in combination of two or more types. The pH adjusting agent may be a commercially available product or a synthetic product.

[0049] The pH adjusting agent is not particularly limited, and known pH adjusting agents used in the field of polishing compositions can be used. Known acids, bases, or salts thereof can be used as pH adjusting agents. Examples of pH adjusting agents include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, melitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, and adipine. Examples include acids, carboxylic acids such as fumaric acid, maleic acid, aconitic acid, amino acids, and anthranilic acid, as well as organic acids such as sulfonic acid and organic phosphonic acid; inorganic acids such as nitric acid, carbonic acid, hydrochloric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, boric acid, and hydrofluoric acid; alkali metal hydroxides such as potassium hydroxide (KOH); alkali metal carbonates such as potassium carbonate (K2CO3) and sodium carbonate (Na2CO3); hydroxides of group 2 elements; ammonia (ammonium hydroxide); and organic bases such as quaternary ammonium hydroxide compounds.

[0050] The amount of pH adjuster in the polishing composition should be appropriately selected to achieve the desired pH value of the polishing composition.

[0051] The pH of the polishing composition shall be the value measured by the method described in the examples.

[0052] [Dispersion medium] The polishing composition according to the present invention may contain a dispersion medium to dissolve and / or disperse each component. The dispersion medium may be used alone or in combination of two or more types.

[0053] The dispersion medium is not particularly limited and includes, for example, water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone; and mixtures thereof. The dispersion medium is preferably water.

[0054] From the viewpoint of not inhibiting the action of the components contained in the polishing composition, water that contains as few impurities as possible is preferable. Preferably, the water has a total transition metal ion content of 100 ppb or less. The purity of the water can be increased, for example, by removing impurity ions using ion exchange resin, removing foreign matter by filtration, or distillation. More preferably, the water is selected from deionized water (ion-exchanged water), pure water, ultrapure water, and distilled water.

[0055] [Other ingredients] The polishing composition according to the present invention may further contain other known components that can be used in polishing compositions, as long as they do not impair the effects of the present invention. Examples of other components include oxidizing agents, antifungal agents (preservatives), complexing agents, and metal corrosion inhibitors. Oxidizing agents and antifungal agents (preservatives) will be described below.

[0056] Examples of oxidizing agents include hydrogen peroxide, sodium peroxide, barium peroxide, ozonated water, silver(II) salts, iron(III) salts, permanganate, chromic acid, dichromate, peroxodisulfate, peroxolinic acid, peroxosulfate, peroxoboric acid, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypochlorous acid, hypobromous acid, hypoiodic acid, chloric acid, chlorous acid, perchloric acid, bromic acid, iodic acid, periodic acid, persulfate, dichloroisocyanuric acid and their salts (e.g., potassium salts, sodium salts, ammonium salts, etc.). Oxidizing agents may be used individually or in combination of two or more.

[0057] Examples of antifungal agents (preservatives) include isothiazoline preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one; phenoxyethanol; and others. Antifungal agents (preservatives) may be used individually or in combination of two or more.

[0058] In one embodiment, the polishing composition according to the present invention may be a one-component type or a multi-component type, including a two-component type.

[0059] [Method for producing abrasive compositions] The method for producing the polishing composition according to the present invention is not particularly limited, and can be obtained, for example, by stirring and mixing abrasive particles, a nonionic surfactant, a pH adjuster as needed, a dispersion medium, and other components. Details of each component are as described above.

[0060] The temperature at which each component is mixed is not particularly limited, but it is preferably between 10°C and 40°C, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited as long as uniform mixing is achieved.

[0061] <Polishing method and method for manufacturing semiconductor substrates> One aspect of the present invention relates to a polishing method that includes the step of polishing an object to be polished containing a carbon film using the above-described polishing composition.

[0062] One aspect of the present invention relates to a method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing a carbon film by the polishing method described above.

[0063] The polishing apparatus is not particularly limited, but a general polishing apparatus can be used, for example, one that has a holder for holding a substrate or the like containing the object to be polished, a motor with a changeable rotation speed, and a polishing platen to which a polishing pad (abrasive cloth) can be attached.

[0064] The polishing pad is not particularly limited, but for example, general nonwoven fabrics, polyurethanes, and porous fluororesins can be used without any particular restrictions. Preferably, the polishing pad has grooves that allow the polishing liquid to accumulate.

[0065] There are no particular restrictions on the polishing conditions. For example, the rotational speed of the polishing platen and head can be 10 rpm (0.17 s). -1 ) or more 500rpm (8.33s -1 Preferably, the pressure applied to the substrate having the object to be polished (polishing pressure) is between 0.5 psi (3.4 kPa) and 10 psi (68.9 kPa).

[0066] The method of supplying the polishing composition to the polishing pad is not particularly limited; for example, a method of continuous supply using a pump or the like can be employed. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with the polishing composition. The polishing time is also not particularly limited; for example, a time that achieves the desired polishing can be appropriately selected.

[0067] After polishing is complete, the substrate containing the polished object may be washed with running water, and any water droplets adhering to the substrate may be removed and dried using a spin dryer or similar device.

[0068] The polishing composition according to the present invention may be a one-component type or a multi-component type, including a two-component type. Furthermore, the polishing composition according to the present invention may be prepared by diluting the stock solution of the polishing composition with a diluent such as water to, for example, three times or more (or, for example, five times or more).

[0069] [Polished carbon film] The polishing composition according to the present invention can polish carbon films at a high polishing speed.

[0070] In the present invention, the lower limit of the carbon film polishing rate is, for example, 80 Å / min or more, preferably 90 Å / min or more, more preferably 140 Å / min or more, and even more preferably 180 Å / min or more.

[0071] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0072] The present invention encompasses the following embodiments and forms. [1] An abrasive composition comprising abrasive particles and a nonionic surfactant, used for polishing objects containing a carbon film. [2] The abrasive composition according to [1], wherein the nonionic surfactant comprises a compound having a polyoxyalkylene glycol structure. [3] The nonionic surfactant comprises a compound represented by the following formula 1, as described in the polishing composition according to [1] or [2]:

[0073] [ka]

[0074] In formula 1, X is an alkylene group having 2 or 3 carbon atoms, m is an integer between 4 and 14, and n is an integer between 3 and 25. [4] The polishing composition according to [3], wherein in formula 1, X is an ethylene group, m is 7 or more and 9 or less, and n is 5 or more and 10 or less. [5] The abrasive composition according to any one of [1] to [4], wherein the content of the nonionic surfactant is 0.01% by mass or more and 0.1% by mass or less with respect to the total mass of the abrasive composition. [6] The abrasive grain comprises colloidal silica, as described in any of [1] to [5]. [7] The abrasive grain comprises anionically modified colloidal silica, as described in any one of [1] to [6]. [8] An abrasive composition according to any one of [1] to [7], wherein the pH is 1.0 or higher and 5.0 or lower. A polishing method comprising the step of polishing an object to be polished containing a carbon film using the polishing composition described in any one of items [9][1] to [8].

[10] A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing a carbon film by the polishing method described in [9]. [Examples]

[0075] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively. Unless otherwise specified, the operations were carried out under room temperature (20°C to 25°C) / relative humidity of 40% RH to 50% RH.

[0076] <Measurement method> (Average primary particle size of abrasive grains) The average primary particle size of the abrasive grains was calculated from the specific surface area of ​​the abrasive grains and the density of the abrasive grains, measured using the BET method with a "Flow Sorb II 2300" manufactured by Micromerities.

[0077] (Average secondary particle size of abrasive grains) The average secondary particle diameter of the abrasive grains was measured as the volume-average particle diameter (volume-based arithmetic mean diameter; Mv) using a dynamic light scattering particle size and particle size distribution analyzer UPA-UT151 (manufactured by Nikkiso Co., Ltd.).

[0078] (pH of the abrasive composition) The pH of the polishing composition was determined using a glass electrode type hydrogen ion concentration indicator (Horiba, Ltd., Model: F-23). ​​After three-point calibration using standard buffers (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)), the glass electrode was placed in the polishing composition, and the pH value after stabilization for at least two minutes was taken. <Comparative Example 1> Sulfonic acid-modified colloidal silica (average primary particle diameter: 15 nm, average secondary particle diameter: 34 nm) was added to pure water as a dispersion medium to a final concentration of 0.4% by mass. Then, nitric acid was added to adjust the pH to 2.8 to prepare the polishing composition.

[0079] <Example 1> To pure water used as a dispersion medium, sulfonic acid-modified colloidal silica (average primary particle diameter: 15 nm, average secondary particle diameter: 34 nm) was added as abrasive particles to a final concentration of 0.4% by mass. Furthermore, polyoxyethylene (10) decyl ether was added as a nonionic surfactant to a final concentration of 0.04% by mass, and the mixture was stirred at room temperature (25°C) for 30 minutes. Subsequently, nitric acid was added to adjust the pH to 2.9 to prepare the polishing composition.

[0080] <Examples 2-3> The polishing composition was prepared in the same manner as in Example 1, except that the concentration of the nonionic surfactant was changed as shown in Table 1 below.

[0081] <Example 4> To pure water used as a dispersion medium, sulfonic acid-modified colloidal silica (average primary particle diameter: 15 nm, average secondary particle diameter: 34 nm) was added as abrasive particles to a final concentration of 0.4% by mass. Furthermore, polyoxyethylene (5) decyl ether was added as a nonionic surfactant to a final concentration of 0.02% by mass, and the mixture was stirred at room temperature (25°C) for 30 minutes. After that, nitric acid was added to adjust the pH to 2.8 to prepare the polishing composition.

[0082] <Example 5> The polishing composition was prepared in the same manner as in Example 4, except that the concentration of the nonionic surfactant was changed as shown in Table 1 below.

[0083] <Example 6> To pure water used as a dispersion medium, sulfonic acid-modified colloidal silica (average primary particle diameter: 15 nm, average secondary particle diameter: 34 nm) was added as abrasive particles to a final concentration of 0.4% by mass. Furthermore, polyoxyethylene (7) octyl ether was added as a nonionic surfactant to a final concentration of 0.06% by mass, and the mixture was stirred at room temperature (25°C) for 30 minutes. Subsequently, nitric acid was added to adjust the pH to 2.8 to prepare the polishing composition.

[0084] <Example 7> The polishing composition was prepared in the same manner as in Example 6, except that the concentration of the nonionic surfactant and the pH of the polishing composition were changed as shown in Table 1 below.

[0085] Table 1 shows the composition of each polishing composition. A "-" in Table 1 indicates that the component was not used.

[0086] <Rating> The surface of the object to be polished was polished using each of the polishing compositions prepared above under the following conditions. The object to be polished was a silicon wafer (300 mm, blanket wafer manufactured by Advance Materials Technology Co., Ltd.) with a 2,000 Å thick spin-on carbon (SoC) film formed on its surface.

[0087] (Polishing equipment and polishing conditions) Polishing equipment: Polishing machine manufactured by Ebara Corporation (model FREX 300E) Polishing pad: Nitta DuPont Supreme RN-H suede pad. Polishing pressure: 1.5 psi (1 psi = 6894.76 Pa) Conditioner (dresser): 3M nylon brush Polishing plate rotation speed: 40 rpm Head rotation speed: 40 rpm Supply of polishing composition: flow-through Polishing composition supply amount: 200mL / min Polishing time: 30 seconds.

[0088] (Evaluation of polishing speed) The thickness of the SoC film before and after polishing was determined using an optical film thickness measuring instrument (ASET-f5x: manufactured by KLA-Tencor Co., Ltd.). From the determined thickness, the polishing rate [unit: Å / min] on the object to be polished was calculated by dividing [(thickness before polishing [unit: Å]) - (thickness after polishing [unit: Å])] by the polishing time [unit: min]. In this invention, for SoC films, a polishing rate of 80 Å / min or higher is considered practical.

[0089] The evaluation results for the polishing speed are shown in Table 1.

[0090] [Table 1]

[0091] As is clear from Table 1, when using the polishing composition according to the example, the SoC film can be polished at a higher polishing speed compared to the polishing composition according to the comparative example.

Claims

1. It contains abrasive particles and a nonionic surfactant, An abrasive composition used for polishing objects containing a carbon film.

2. The polishing composition according to claim 1, wherein the nonionic surfactant comprises a compound having a polyoxyalkylene glycol structure.

3. The nonionic surfactant comprises a compound represented by the following formula 1, wherein the polishing composition is as described in claim 2: 【Chemistry 1】 In formula 1, X is an alkylene group having 2 or 3 carbon atoms, m is an integer between 4 and 14, and n is an integer between 3 and 25.

4. The polishing composition according to claim 3, wherein in formula 1, X is an ethylene group, m is 7 or more and 9 or less, and n is 5 or more and 10 or less.

5. The abrasive composition according to claim 1, wherein the content of the nonionic surfactant is 0.01% by mass or more and 0.1% by mass or less, based on the total mass of the abrasive composition.

6. The abrasive composition according to claim 1, wherein the abrasive grains include colloidal silica.

7. The abrasive composition according to claim 1, wherein the abrasive grains include anionically modified colloidal silica.

8. The polishing composition according to claim 1, wherein the pH is 1.0 or higher and 5.0 or lower.

9. A polishing method comprising the step of polishing an object to be polished containing a carbon film using the polishing composition described in any one of claims 1 to 8.

10. A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing a carbon film by the polishing method described in claim 9.

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