Polishing composition and polishing method using the same

Abstract

This invention provides a polishing composition and a polishing method using the same, which can increase the polishing speed of silicon-containing materials, have a high selectivity ratio of silicon-containing materials to other materials (e.g., nitride materials), and maintain the stability of the composition. [Solution] The polishing composition has a surface modified with a silane coupling agent, has a positive surface potential, has an average secondary particle diameter of 45 nm or more and 100 nm or less, and has a silanol group density of 0.0 / nm 2 Larger than 3.0 particles / nm 2 The following abrasive particles, a surfactant which is an alkyl phosphate with 6 to 18 carbon atoms, and an aqueous dispersion medium are included.

Description

[Technical Field]

[0001] This invention provides an abrasive composition and a polishing method using the same. [Background technology]

[0002] In recent years, with the advancement of semiconductor technology, semiconductor substrate designs have become even smaller, and the number of stacked layers has increased. However, in order to make the circuit structure of each layer flat, various polishing processes, such as chemical mechanical polishing (CMP), are usually used to improve the flatness of the semiconductor substrate surface or wafer surface. Chemical mechanical polishing technology typically uses a chemical mechanical polishing composition containing abrasive particles, surfactants, etc., to polish the object to be polished.

[0003] Examples of materials to be polished include materials containing nitrides such as TiN, or materials containing single-crystal silicon, polycrystalline silicon, silica, silicon nitride, etc. Therefore, since the material of the material to be polished differs in each process, or the desired function differs, it is necessary to control the polishing rate for each material.

[0004] For example, Patent Document 1 discloses a method for maintaining the original polishing performance of a polishing target object containing silicon materials having silicon-silicon bonds. Patent Document 2 discloses a polishing composition that can improve the polishing speed of metals with excellent embedding properties (especially tungsten) while maintaining the stability of the composition. Patent Document 3 discloses a polishing composition that can polish materials containing silicon atoms or materials such as TiN at high speed. From Patent Documents 1 to 3, it can be seen that the composition of a polishing composition usually differs depending on its purpose and the object being polished. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-158752 [Patent Document 2] Japanese Patent Publication No. 2021-161385 [Patent Document 3] Japanese Patent Publication No. 2022-108413 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the chemical mechanical polishing compositions disclosed in Patent Documents 1 to 3 do not consider the selectivity ratio between silicon and other materials (e.g., nitride materials).

[0007] Therefore, the object of the present invention is to provide a polishing composition that can increase the polishing speed of silicon-containing materials, has a high selectivity ratio of silicon-containing materials to other materials (e.g., nitride materials), and maintains the stability of the composition. [Means for solving the problem]

[0008] To achieve the above objective, one aspect of the present invention provides an abrasive composition having a surface modified with a silane coupling agent, having a positive surface potential, an average secondary particle diameter of 45 nm to 100 nm, and a silanol group density of 0.0 / nm 2 Larger than 3.0 particles / nm 2 The present invention provides an abrasive composition comprising the following abrasive particles, a surfactant which is an alkyl phosphate having 6 to 18 carbon atoms, and an aqueous dispersion medium.

[0009] Another aspect of the present invention is a polishing method capable of achieving the above-mentioned objectives, A polishing method comprising the steps of: preparing a polishing apparatus including a polishing pad and a polishing head; preparing a substrate between the polishing pad and the polishing head; introducing a polishing composition between the substrate and the polishing pad, and then polishing the substrate, wherein the polishing composition has a surface modified with a silane coupling agent, has a positive surface potential, has an average secondary particle diameter of 45 nm or more and 100 nm or less, and has a silanol group density of 0.0 / nm2 Larger than 3.0 particles / nm 2 The present invention further provides a polishing method comprising the following abrasive grains, a surfactant which is an alkyl phosphate having 6 to 18 carbon atoms, and an aqueous dispersion medium. [Effects of the Invention]

[0010] The polishing composition of the present invention exhibits a high removal rate for silicon-containing materials, while simultaneously suppressing the polishing rate for other materials (i.e., high selectivity for materials other than silicon, such as nitride films), and maintains excellent stability even under high-temperature conditions for extended periods. By using the above-mentioned polishing composition, the polishing method of the present invention can obtain a semiconductor substrate surface or wafer surface with the desired effect, and can also reduce the manufacturing cost of the semiconductor substrate or wafer. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0012] Where “includes” is used herein, it will be understood that it indicates the presence of components, integers, steps, operations, elements, compositions, and / or groups thereof of the described features, but does not exclude the presence or increase of one or more other components, integers, steps, operations, elements, compositions, and / or groups thereof. Where the singular form is used herein, it is intended to include the plural form unless otherwise specified in the surrounding sentences.

[0013] In this specification, the expression "a~b" used to represent a specific numerical range is defined as "≧a, ≦b" (greater than or equal to a, less than or equal to b).

[0014] <Polishing composition> The abrasive composition of the present embodiment has a surface modified with a silane coupling agent, has a positive surface potential, an average secondary particle diameter of 45 nm or more and 100 nm or less, and a silanol group density greater than 0.0 / nm 2 and less than 3.0 per nm 2 and includes abrasive grains, a surfactant that is an alkyl phosphate having 6 to 18 carbon atoms, and an aqueous dispersion medium.

[0015] In one or more embodiments, the abrasive composition is suitable for use in treating a specific object to be polished, for example, during the process of a semiconductor device. In one embodiment, examples of the object to be polished include surfaces containing, for example, single crystal silicon, polycrystalline silicon, silicon oxide, silicon nitride, other silicon compounds, metal nitrides, etc. Among them, the abrasive composition is suitable for use in polishing a semiconductor substrate containing silicon oxide. It is also particularly suitable for use in polishing a semiconductor substrate further containing a metal nitride. Examples of metal nitride materials include, but are not limited to, titanium nitride (TiN), tantalum nitride, or combinations thereof. In one embodiment, there is an example of polishing the polishing rate of silicon oxide at a high speed with respect to the metal nitride. In one embodiment, there is no particular limitation on the above-described treatment method, and for example, polishing treatment, selective polishing treatment, cleaning treatment, etc. can be performed. The abrasive composition of the present embodiment is preferably used for polishing treatment and selective polishing treatment.

[0016] The abrasive composition of the present embodiment will be described in detail below. [[ID=!3]]

[0017] <Abrasive grains> Examples of the abrasive grains in the abrasive composition include, but are not limited to, alumina, silica, zirconia, diamond or silicon carbide. The abrasive grains may be used alone or in combination of two or more kinds. Commercially available products or synthetic products may be used as the abrasive grains.

[0018] The abrasive grains are abrasive grains whose surface has a positive surface potential, and may be referred to as cation-modified abrasive grains below. Preferably, they are colloidal silica having cationic groups (cation-modified colloidal silica), and particularly preferably colloidal silica having amino groups (amino-group modified colloidal silica). Abrasive grains having cationic groups can further increase the polishing speed of the object to be polished, including the silica film. In addition, generally, the surface of metal nitrides usually carries a positive charge in an acidic environment. Therefore, a repulsive force is generated between the abrasive grains having cationic groups with a positive surface potential and the metal nitride surface. This avoids collisions between the abrasive grains and the metal nitride surface, and consequently suppresses the occurrence of scratches. However, this mechanism is based on speculation, and the present invention is not affected by such speculation.

[0019] In one or more embodiments, abrasive grains are surface-modified by chemical treatment with a silane coupling agent having amino groups. In this specification, surface modification by chemical treatment is also referred to as chemical surface modification. By chemical surface treatment, amino groups are immobilized on the surface of the abrasive grains and cationized. This immobilization is by chemical bonding, not physical adsorption. As a method for producing abrasive grains having amino groups, one example is to immobilize a silane coupling agent having amino groups, such as aminoethyltrimethoxysilane, on the surface of silica particles, as described in Japanese Patent Application Publication No. 2005-162533.

[0020] In this specification, a silane coupling agent having an amino group is referred to as an "aminosilane coupling agent."

[0021] Examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane ((3-aminopropyl)triethoxysilane,APTES), 4-amino-3,3-dimethylbutyltriethoxysilane, N-methylaminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, 2-(4-pyridylethyl)triethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylsilanetriol, 3-trimethoxysilylpropyldiethyldiethylenetriamine, and N,N'-bis[(3-trimethoxysilyl)propyl]ethylenediamine. Examples include ethylenediamine, [3-(1-piperazinyl)propyl]methyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, and bis[3-(trimethoxysilyl)propyl]amine.

[0022] Specifically, an aminotrialkoxysilane having the structure shown in formula (1) below can be used as an aminosilane coupling agent. In formula (1), X is a molecule with 1 to 10 carbon atoms (C1-C1). 10(The same applies below.) Alkyl groups, aminoalkyl groups containing one or more nitrogen atoms (C1~C 10 ), or a single bond. Also, R1, R2, and R3 are each independently an alkyl group (C1-C3), hydrogen (H), or a salt thereof. The salt may be, for example, a hydrochloride salt.

[0023] [ka]

[0024] Examples of the above-mentioned aminotrialkoxysilanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane (APTES), 4-amino-3,3-dimethylbutyltriethoxysilane, N-methylaminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylsilanetriol, and 3-trimethoxysilylpropyldiethyldiethylenetriamine. Of the above-mentioned aminosilane coupling agents, 3-aminopropyltriethoxysilane (APTES) has the structure shown in formula (2). When 3-aminopropyltriethoxysilane is used as an aminosilane coupling agent, aminopropyl groups are immobilized on the surface of the abrasive grains and cationized.

[0025] [ka]

[0026] The zeta (ζ) potential of cationized abrasive grains surface-modified by chemical treatment with an aminosilane coupling agent is preferably 10 mV or higher, more preferably 20 mV or higher, and even more preferably 30 mV or higher under acidic conditions. From the viewpoint of stably obtaining a positive zeta potential, it is preferable to use the above-mentioned aminotrialkoxysilane as the aminosilane coupling agent, and among them, APTES is preferred.

[0027] In chemical treatment, aminosilane coupling agents form chemical bonds, such as Si-O-Si bonds, with colloidal silica through hydrolysis and dehydration condensation reactions. Under acidic conditions, the zeta potential of cationized colloidal silica surface-modified by this chemical treatment with aminosilane coupling agents has a larger positive value compared to unmodified colloidal silica. This makes it easier to obtain the effects of the present invention. Furthermore, ordinary colloidal silica has a zeta potential close to zero under acidic conditions, so the colloidal silica particles do not electrically repel each other and tend to aggregate. In contrast, even under acidic conditions, the particles of cationized colloidal silica strongly repel each other, disperse well, and are less prone to aggregation. As a result, the storage stability of the polishing composition is improved. However, this mechanism is based on speculation, and the present invention is not affected by such speculation.

[0028] From the viewpoint of polishing speed, the aspect ratio of surface-modified abrasive grains is preferably 1.0 or higher, more preferably 1.02 or higher, even more preferably 1.05 or higher, and even more preferably 1.10 or higher. Furthermore, the aspect ratio of surface-modified cationized colloidal silica is preferably less than 1.4, more preferably 1.35 or lower, even more preferably 1.25 or lower, and most preferably 1.20 or lower. This makes it possible to achieve good surface roughness of the object to be polished, which is caused by the shape of the abrasive grains. It also suppresses the occurrence of defects caused by the shape of the abrasive grains. Note that this aspect ratio is the average value obtained by dividing the length of the long side of the smallest rectangle circumscribing the colloidal silica particles by the length of the short side of the same rectangle, and can be determined from images of abrasive grains obtained by scanning electron microscopy using general image analysis software.

[0029] The average primary particle diameter of the abrasive grains in this embodiment is preferably 100 nm or less, more preferably 70 nm or less, even more preferably 50 nm or less, and then, in order, more preferably 40 nm or less and 35 nm or less. Furthermore, the average primary particle diameter of the abrasive grains in this embodiment is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, even more preferably 25 nm or more, even more preferably 30 nm or more, even more preferably 35 nm or more, and most preferably greater than 35 nm. Within this range, the polishing speed of the object to be polished with the polishing composition is improved. In addition, dishing on the surface of the object to be polished after polishing with the polishing composition can be further suppressed. The average primary particle diameter of colloidal silica is calculated, for example, based on the specific surface area of ​​colloidal silica measured by the BET method.

[0030] The average secondary particle diameter of the abrasive grains in this embodiment is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, even more preferably 100 nm or less, and then, in order, most preferably 90 nm or less, 80 nm or less, and 75 nm or less. Furthermore, the average secondary particle diameter of the abrasive grains in this embodiment is preferably 50 nm or more, more preferably 55 nm or more, even more preferably 60 nm or more, and even more preferably 63 nm or more. Within this range, the polishing speed of the object to be polished with the polishing composition is improved. In addition, the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition can be further suppressed.

[0031] Secondary particles refer to particles formed when colloidal silica (primary particles) with organic acids immobilized on its surface associate in the polishing composition. The average secondary particle diameter can be measured, for example, by dynamic light scattering.

[0032] In one or more embodiments, the abrasive grains used in the embodiment have silanol groups on their surfaces. As used herein, the "silanol group" refers to a hydroxyl group directly bonded to a silicon atom on the surface of silica particles, and there are no particular restrictions on the configuration or coordination. Also, there are no particular restrictions on the conditions for generating the silanol groups. As used herein, the "silanol group density" refers to the number of silanol groups per unit area on the surface of silica particles, and is an index representing the electrical or chemical properties of the silica particle surface. In embodiments where silica may be included in the abrasive grains, the silanol group density of the abrasive grains is 0 to 5.0 per nm 2 is preferred, 0.5 to 3.0 per nm 2 is more preferred, 1.0 to 3.0 per nm 2 is even more preferred, 1.5 to 3.0 nm 2 is even more preferably, 1.5 to 2.5 per nm 2 is most preferred. When the abrasive grains in the polishing composition have a silanol group density within the above range, the polishing composition can achieve good polishing characteristics and has better stability.

[0033] Here, the silanol group density of the abrasive grains in the polishing composition is calculated based on the specific surface area measured by the BET method and the amount of silanol groups measured by titration. For example, the average silanol group density (unit: per nm 2 ) on the surface of silica (abrasive grains) can be calculated by the Sears titration method using neutral titration described in "Analytical Chemistry, vol.28, No.12, 1956, 1982 - 1983" by G.W. Sears.

[0034] Here, the shape of the abrasive grains used in this embodiment is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular or square prisms, cylindrical shapes, cylindrical shapes with a bulge in the center, ring shapes (donut shapes) with a hole in the center of a disc, plate shapes, so-called cocoon shapes with a constriction in the center, so-called aggregate spherical shapes where multiple particles are integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, and various other shapes, and are not particularly limited.

[0035] The abrasive content (concentration) used in this embodiment is not particularly limited. Assuming a total weight of 100 wt%, the abrasive content in the polishing composition is preferably 0.01 wt% or more, more preferably 0.1 wt% or more, even more preferably 1 wt% or more, and most preferably 1.5 wt% or more. The higher the abrasive content in the polishing composition, the higher the removal rate of the polishing composition from the object to be polished. The abrasive content in the polishing composition is preferably 20 wt% or less, more preferably 15 wt% or less, and most preferably 10 wt% or less. The lower the abrasive content in the polishing composition, the lower the scratch defect rate on the surface of the object to be polished. In other words, the abrasive content in the polishing composition is preferably in the range of 0.01 to 20 wt%, more preferably in the range of 0.1 to 15 wt%, and most preferably in the range of 1 to 10 wt%. In one embodiment, the abrasive content in the polishing composition is preferably in the range of 0.01 to 20 wt%, more preferably in the range of 0.1 to 15 wt%, even more preferably in the range of 1 to 10 wt%, and most preferably in the range of 1.5 to 5 wt%. When the abrasive content in the polishing composition is within the above range, the polishing composition can maintain a low scratch defect rate on the object to be polished while increasing the removal rate from the object to be polished, thereby providing excellent polishing properties.

[0036] <Surfactants> The surfactant used in the polishing composition in one or more embodiments is a surfactant having 6 to 18 carbon atoms (C6-C6). 18It may be an alkyl phosphate (ester) of 6-C6. The number of carbon atoms in the alkyl phosphate is preferably 6 or more, more preferably 8 or more, and even more preferably 10 or more. Furthermore, the number of carbon atoms in the alkyl phosphate is preferably 19 or less, more preferably 18 or less, even more preferably 16 or less, and even more preferably 14 or less. In one embodiment, the number of carbon atoms is from 6 to 18 (C6-C6 18 It is preferable that the alkyl group of the alkyl group is directly bonded to the phosphate, that is, that the alkyl group and the phosphate are not bonded together by an alkenyl group, an alkyne group, or other heteroatoms. In another embodiment, the alkyl phosphate may be an alkyl phosphate formed by bonding a phosphate with one or more alkyl groups, and it is preferable that it is a monoalkyl phosphate formed by bonding a phosphate with one alkyl group. When polishing an object to be polished with the polishing composition containing the above alkyl phosphate, scratches caused by abrasive grains can be suppressed, and consequently the substrate surface can be protected. However, if the alkyl chain is excessively long, the solubility becomes insufficient, which reduces the stability of the polishing composition and makes it impossible to store for a long time.

[0037] Furthermore, the term "carbon number 6 to 18 (C6-C)" as used herein refers to the term "carbon number 6 to 18 (C6-C) 18 A "monovalent alkyl group" refers to a monovalent alkyl group obtained by removing one hydrogen atom from a saturated hydrocarbon molecule containing 6 to 18 carbon atoms. C6-C 18The alkyl group may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group. Examples of the linear alkyl group include, but are not limited to, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, lauryl group (dodecane group), tridecane group, myristyl group (tetradecane group), pentadecane group, palmityl group (hexadecane group), heptadecane group, stearyl group (octadecane group), etc. Examples of the branched alkyl group include, but are not limited to, isohexyl group, isoheptyl group, isooctyl group, isononyl group, isodecyl group, isoundecane group, isododecane group, isotridecane group, isotetradecane group, isopentadecane group, isohexadecane group, isoheptadecane, etc. In one embodiment, it is more preferable to use a phosphate having a linear or branched alkyl group as the alkyl phosphate having 6 to 18 carbon atoms (C6-C 18 ), and it is even more preferable that the phosphate does not have a linear or branched alkyl group substituted with any substituent on the main chain or side chain of the alkyl group. In one or more embodiments, examples of the surfactant include hexyl phosphate, heptyl phosphate, octyl phosphate, 2-ethylhexyl phosphate, decyl phosphate, dodecyl phosphate / lauryl phosphate, myristyl phosphate, stearyl phosphate, etc.

[0038] There is no particular limitation on the content (concentration) of the surfactant. The concentration of the surfactant is preferably 0.1 to 1.0 g / L, more preferably 0.15 to 0.8 g / L, and even more preferably 0.2 to 0.5 g / L. When the polishing composition contains a surfactant having a content within the above range, the removal rate for the silicon-containing material increases, and the selectivity ratio for other materials (for example, metal nitride) other than the silicon material increases.

[0039] <pH adjuster> In one or more embodiments, the polishing composition may further contain a pH adjuster. The pH value of the polishing composition can be adjusted by adding a pH adjuster, thereby enhancing the chemical polishing effect of the polishing composition or improving the dispersion stability of the polishing composition. In one embodiment, the pH adjuster used in the polishing composition may be, for example, an acid. It is preferable not to use an inorganic acid, and more preferable to use an organic acid. In another embodiment, the pH adjuster used in the polishing composition is more preferably a carboxylic acid (excluding amino acids) or an amino acid.

[0040] In one or more embodiments, when the pH adjusting agent used in the polishing composition is a carboxylic acid, examples of carboxylic acids include, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-pentanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, and lactic acid. In one embodiment, the carboxylic acid may be, for example, a carboxylic acid with an even number of carbon atoms, and is preferably a dicarboxylic acid. In another embodiment, the carboxylic acid may be succinic acid, adipic acid, tartaric acid, or a combination thereof, and is preferably tartaric acid.

[0041] In one or more embodiments, when the pH adjusting agent used in the polishing composition is an amino acid, examples of the amino acid include, for example, acidic amino acids such as glutamic acid, aspartic acid, or combinations thereof, and aspartic acid is preferred.

[0042] The amount (concentration) of pH adjuster to be added can be appropriately selected to bring the polishing composition to the desired pH value, and it is preferable to select an amount that brings the polishing composition to the preferred pH value described later.

[0043] The pH value of the polishing composition of this embodiment is preferably 2 or higher, more preferably 2.5 or higher, and even more preferably 3 or higher. The pH value of the polishing composition of this embodiment is more preferably less than 6, even more preferably 5.5 or lower, and particularly preferably 5 or lower. The pH value of the polishing composition of this embodiment is preferably within the range of 3 to 5, and even more preferably within the range of 3 to 4. When the pH is within the above range, the removal rate of silicon oxide by the polishing composition of this embodiment is increased, and the selectivity ratio of silicon material to other materials (e.g., metal nitrides such as TiN) can be increased, and stability is further enhanced.

[0044] Furthermore, the pH of the polishing composition can be measured using a pH meter. After calibrating the pH meter at three points using a standard buffer solution, a glass electrode is placed in the polishing composition. Then, after waiting for at least two minutes for the pH to stabilize, the pH of the polishing composition can be accurately determined by measuring the value.

[0045] <Aqueous dispersion medium> The function of the aqueous dispersion medium in the polishing composition is to dissolve or disperse each of the above-mentioned components in the polishing composition. There are no particular restrictions on the example of the aqueous dispersion medium. Furthermore, there are no particular restrictions on the water content in the aqueous dispersion medium, but it is preferably 50 wt% or more, more preferably 90 wt%, and even more preferably water alone, based on the total weight of the aqueous dispersion medium. From the viewpoint of suppressing contamination of the object to be polished and inhibiting the action of other components, water that contains as few impurities as possible is preferred as the dispersion medium. As such water, water with a total content of transition metal ions of 100 ppb or less is preferred. Here, the purity of the water can be increased by operations such as removal of impurity ions using ion exchange resin, removal of foreign matter by filtration, and distillation. Specifically, it is preferable to use deionized water (ion-exchanged water), pure water, ultrapure water, distilled water, etc. as the water. In one embodiment, the aqueous dispersion medium contains deionized water.

[0046] Within the limits that do not significantly impair the effects of the present invention, the aqueous dispersion medium may be a mixed solvent of water and an organic solvent. There are no particular restrictions on the organic solvent, and known organic solvents can be used. When a mixed solvent of water and an organic solvent is used, the organic solvent mixed with water is preferred. When using an organic solvent, the water and organic solvent may be mixed to make a mixed solvent, and then each component may be added to the mixed solvent and mixed, or each component may be dispersed or dissolved in the organic solvent and then mixed with water. Furthermore, the organic solvent may be used alone or in combination of two or more types.

[0047] <Other ingredients> The polishing composition of this embodiment may further contain other components, as long as they do not impair the effects of the present invention. The other components are not particularly limited, but can be appropriately selected from various components used in known polishing compositions, such as wetting agents, chelating agents, preservatives, fungicides, dissolved gases, reducing agents, etc.

[0048] <Form of abrasive composition> The polishing composition of this embodiment may be a one-component type or a multi-component type, including a two-component type. The multi-component type is a combination of liquids obtained by mixing some or all of the polishing composition in any mixing ratio. The polishing composition may also be in the form of a concentrated stock solution. In this case, it can be used for polishing by diluting it with a diluent such as water, for example, 2 to 10 times or more.

[0049] <Method for producing abrasive compositions> The method for producing the polishing composition of this embodiment is not particularly limited, and it can be produced by stirring and mixing abrasive grains, a surfactant, and other components as needed (e.g., pH adjusters) in an aqueous dispersion medium (e.g., water). Details of each component are as described above. The temperature at which each component is mixed is not particularly limited, as long as the components in the polishing composition are uniformly mixed.

[0050] <Polishing method> Another aspect of the present invention provides a polishing method for polishing an object to be polished using the above-described polishing composition. The polishing method using the polishing composition of this embodiment is not particularly limited, but chemical mechanical polishing is preferred. The polishing process may consist of a single step or a multi-step process. A multi-step polishing process may, for example, consist of a pre-polishing step (rough polishing step) followed by a final polishing step, or a primary polishing step followed by one or more secondary polishing steps before the final polishing step.

[0051] <Polishing equipment> In one or more embodiments, the polishing apparatus using the polishing composition of this embodiment is not particularly limited and may be, for example, an apparatus capable of performing planarization, selection, and cleaning treatments on the workpiece. The surface treatment apparatus (polishing apparatus) may be a general polishing apparatus having a holder for holding a substrate or the like having the workpiece to be polished, a motor with a changeable rotation speed, and a polishing platen to which a polishing pad (polishing cloth) can be attached.

[0052] As the polishing pad, 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.

[0053] In one embodiment, there are no particular restrictions on the polishing conditions used in the polishing method, and appropriate conditions can be set as appropriate according to the characteristics of the polishing composition and the object to be polished. For example, the rotation speed of the polishing platen and the carrier rotation speed are not particularly limited, but are preferably 10 rpm to 500 rpm, more preferably 20 rpm to 300 rpm, even more preferably 30 rpm to 200 rpm, and still more preferably 40 rpm to 150 rpm. The pressure applied to the substrate having the object to be polished (polishing pressure) is not particularly limited, but is generally preferably 0.1 psi to 10 psi per unit area, more preferably 0.5 psi to 8 psi, and still more preferably 1 psi to 5 psi. Within this range, it is possible to obtain a high polishing speed while further suppressing damage to the substrate due to the load and the occurrence of defects such as scratches on the surface. The method of supplying the polishing composition is also not particularly limited, and a method of continuous supply using a pump or the like (flow-through) may be adopted. The amount of polishing composition supplied is usually preferably an amount that covers the surface of the polishing pad of the polishing composition of this embodiment, but is not particularly limited. After polishing is complete, the substrate is washed with running water, for example, and dried by blowing away any water droplets adhering to the substrate with a spin dryer or the like to obtain a substrate with a treated surface.

[0054] <Selection Ratio> In one embodiment, polishing is performed on an object to be polished using the polishing composition of this embodiment, and the selectivity ratio is calculated by dividing the polishing rate of SiN (silicon nitride film) (Å / min) by the polishing rate of TEOS (silicon oxide film) (Å / min). In this embodiment, the selectivity ratio (TEOS / SiN) is preferably 100 or more, and more preferably 200 or more, 400 or more, 600 or more, 800 or more, 1000 or more, 1500 or more, 2000 or more, or 2500 or more. The above selectivity ratio is a value determined based on each polishing rate measured by the method described in the example.

[0055] While embodiments of the present invention have been described in detail, these are for illustrative purposes only and are not intended to be limiting, and it should be understood that the scope of the present invention should be interpreted in accordance with the appended claims.

[0056] The present invention includes the following embodiments and forms.

[0057] 1. The surface is modified with a silane coupling agent, has a positive surface potential, has an average secondary particle diameter of 45 nm or more and 100 nm or less, and has a silanol group density of 0.0 / nm. 2 Larger than 3.0 particles / nm 2 An abrasive composition comprising the following abrasive particles, a surfactant which is an alkyl phosphate having 6 to 18 carbon atoms, and an aqueous dispersion medium.

[0058] 2. The polishing composition described in 1. above, further comprising a pH adjuster.

[0059] 3. The polishing composition according to 2. above, wherein the pH adjusting agent is a carboxylic acid (excluding amino acids) or an amino acid.

[0060] 4. The polishing composition according to 3. above, wherein the carboxylic acid has an even number of carbon atoms.

[0061] 4-2. The polishing composition according to 3. above, wherein the carboxylic acid is a dicarboxylic acid.

[0062] 4-3. The polishing composition according to 3. above, wherein the carboxylic acid is at least one selected from the group consisting of succinic acid, adipic acid, and tartaric acid.

[0063] 4-4. The polishing composition according to 3. above, wherein the carboxylic acid is tartaric acid.

[0064] 5. The polishing composition according to 3. above, wherein the amino acid is an acidic amino acid.

[0065] 5-2. The polishing composition according to 3. above, wherein the amino acid is at least one selected from the group consisting of glutamic acid and aspartic acid.

[0066] 5-3. The polishing composition according to 3. above, wherein the amino acid is aspartic acid.

[0067] 6. The polishing composition according to 1. above, wherein the pH value of the polishing composition is in the range of 3 to 5.

[0068] 7. The polishing composition according to 1. above, wherein the surfactant is an alkyl phosphate having 8 to 15 carbon atoms.

[0069] 7-2. The polishing composition according to 1. above, wherein the surfactant is an alkyl phosphate having 10 to 14 carbon atoms.

[0070] 8. The polishing composition according to item 1 above, wherein the concentration of the surfactant is 0.1 to 1.0 g / L.

[0071] 9. The polishing composition according to 1. above, wherein the abrasive grains are modified with a silane coupling agent having an amino group.

[0072] The polishing composition according to 9. above, wherein the silane coupling agent is (3-aminopropyl)triethoxysilane (APTES).

[0073] 11. A polishing method comprising the steps of preparing a polishing apparatus including a polishing pad and a polishing head, setting an object to be polished between the polishing pad and the polishing head, and polishing the object to be polished using the polishing composition described in any one of items 1 to 10 above.

[0074] 12. The polishing method according to 11. above, wherein the object to be polished is a substrate including a first surface facing the polishing head and being the outermost surface, and a second surface located below it, and the polishing method is used to polish an object in which at least a metal nitride is present on the second surface of the substrate.

[0075] 13. The polishing method according to 12. above, wherein the metal nitride contains titanium nitride (TiN).

[0076] 14. A method for manufacturing a semiconductor substrate, including the polishing method described in 11. above.

[0077] [Examples] The present invention will be described in more detail below using examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Also, unless otherwise specified, "%" refers to "weight % (wt%)". Furthermore, in the examples described later, unless otherwise specified, all polishing operations were carried out under room temperature (20-25°C) / relative humidity of 40-50%RH.

[0078] <Preparation of polishing composition> (Example 1) 0.3 g of (3-aminopropyl)triethoxysilane (APTES) as additive 1 was diluted in ultrapure water and then added to 1 kg of 20 wt% colloidal silica while stirring. The stirring speed was set to 230 rpm, and the dilution rate was set to 10 ml / min. After addition, stirring was continued at 230 rpm for 4 hours to bond (couple) the (3-aminopropyl)triethoxysilane to the surface of the colloidal silica.

[0079] 130 g of colloidal silica with additive 1 adsorbed onto it was weighed out, and 400 g of ultrapure water was added to it, along with 0.15 g of dodecyl phosphate as additive 2. Next, an arbitrary amount of tartaric acid as a pH adjuster and ultrapure water were added until the final volume was 1000 g, and the final concentration of colloidal silica in the polishing composition was adjusted to 2 wt%.

[0080] (Examples 2-15, Comparative Examples 1-9) Examples 2 to 15, Comparative Examples 1 to 5, and Comparative Examples 8 to 9 were prepared according to the preparation method of Example 1. Abrasive grains, Additive 1, and Additive 2 were mixed with a dispersion medium (ultrapure water) referring to the concentrations in Tables 1 to 5, and adjusted to the numerical values shown in Tables 1 to 5 with a pH adjuster, thereby preparing the polishing compositions of Examples 2 to 15, Comparative Examples 1 to 5, and Comparative Examples 8 to 9. Also, in Comparative Example 6, the preparation was carried out in the same manner as the preparation method of Example 1, except that no additive was used. In Comparative Example 7, the preparation was carried out in the same manner as the preparation method of Example 1, except that the surface treatment method of colloidal silica was different. Specifically, in Comparative Example 7, after bonding (coupling) a silane coupling agent of 3-mercaptopropyltrimethoxysilane to colloidal silica, the sulfhydryl group was oxidized with hydrogen peroxide to obtain colloidal silica having sulfonic acid bonded to the surface.

[0081] <Measurement of pH value> The pH of the above polishing composition can be confirmed using a pH meter (LAQUA F-73, manufactured by Horiba, Ltd.). The pH value of the polishing composition was measured at a measurement temperature of 25°C. Also, the average secondary particle diameter of the colloidal silica in these examples was measured using a laser light scattering measurement device (Zetasizer Ultra, manufactured by Malvern Panalytical).

[0082] Hereinafter, “-” in Tables 1 to 5 indicates that the component is not added. The compounds used to prepare the polishing compositions in Tables 1 to 5 and their properties are shown as follows. (3-Aminopropyl)triethoxysilane (APTES) 3-Mercapto propyltrimethoxysilane Tetraethylammonium hydroxide (TEAH) Cetyltrimethylammonium bromide Hexyl phosphate Octyl phosphate 2-Ethylhexyl phosphate dodecyl phosphate Hexadecyl phosphate eicosyl phosphate tartaric acid L-aspartic acid (hereinafter referred to as "aspartic acid")

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

[0086] [Table 4]

[0087] [Table 5]

[0088] <Polishing performance evaluation> (Preparation of the object to be polished) For polishing, we prepared wafers with a 12,000 Å thick tetraethyl orthosilicate (TEOS) film deposited by plasma-enhanced chemical vapor disposition (PECVD), or wafers with a 3,600 Å thick titanium nitride film deposited by physical vapor deposition (PVD).

[0089] (polishing conditions) Using the polishing composition obtained by preparing the polishing composition described above, the wafers were polished under the following conditions.

[0090] Polishing equipment: CMP polishing machine (manufactured by Ebara Corporation, product name: FREX 300SII) Polishing pad: Polyurethane pad (manufactured by Dow Electronic Materials, product name: IC1010) Dresser: Diamond dresser (manufactured by 3M, product name: A188) Polishing time for TEOS film: 60 seconds TiN film polishing time: 60 seconds Polishing plate pressure: 140 hPa (2.03 psi) Polishing plate rotation speed: 90 rpm Carrier rotation speed: 91 rpm Supply rate of polishing composition: 200 ml / min (Dressing conditions) The polishing pads were dressed using pure water under the following conditions. The polishing equipment, polishing pads, and dresser used were the same as those used in the polishing conditions described above.

[0091] Polishing plate rotation speed during dressing: 90 rpm Pressure applied to the polishing platen (polishing pad) of the dresser: 22N Dressing time: In-situ Flow rate of purified water used when adding dressing: 2,000 ml / min (Calculation of polishing speed) To assess the condition of the TEOS film, the film thickness before and after polishing was measured using a spectroscopic ellipsometry film thickness analyzer (KLA-Tencor, product name: ASET F5x), and the polishing rate for the TEOS film was calculated based on the difference in thickness.

[0092] For the TiN film, the film thickness before and after polishing was measured using a sheet resistance type film thickness measuring device (KLA-Tencor, product name: OmniMap RS-100), and the polishing rate for the TiN film was calculated based on the difference in thickness.

[0093] (Measurement of stability) Using a disk centrifugal particle size distribution analyzer (CPS INSTRUMENTS, product name: DC24000UHR), the median diameter (D50) of silica was measured immediately after preparing the polishing compositions of Examples 1 to 15 and Comparative Examples 1 to 9, and again after storage at 80°C for two weeks. When the change in the median diameter (D50) of silica was 5% or less, the stability of the polishing composition was judged to be good (indicated by ○), and when the change in the median diameter (D50) of silica exceeded 5%, the stability of the polishing composition was judged to be poor (indicated by ×).

[0094] The evaluation results of the polishing compositions of the above examples and comparative examples are shown in Table 6 below. In the "Selectivity Ratio" column of Table 6, the "TEOS / TiN" column shows the value obtained by dividing the polishing rate of silica by the polishing rate of TEOS.

[0095] [Table 6]

[0096] As can be seen from the results in Table 6 above, the polishing compositions of Examples 1 to 14 exhibit superior stability compared to the polishing compositions of Comparative Examples 3, 6, 8, and 9. The polishing compositions of Examples 1 to 10 had a removal rate of 1000 Å / min or more for silicon and a removal rate of 20 Å / min or less for titanium nitride. As is clear from this, the selectivity ratio of silica to titanium nitride in the polishing compositions of the present invention is high (the selectivity ratio is greater than 100 in all cases), and in particular, the polishing compositions of Examples 2 to 4, 7 to 10, 12, and 14 to 15 have a selectivity ratio of 500 or more. [Industrial applicability]

[0097] The present invention provides an abrasive composition that exhibits a high removal rate for silicon, a high selectivity ratio for silicon materials compared to other materials (e.g., nitride films), and excellent stability.

[0098] The features of the embodiments described above are useful for a person with ordinary skill in the art to understand the present invention. A person with ordinary skill in the art will understand that the same objectives and / or advantages as the embodiments described above can be achieved by designing and modifying other processes and structures based on the present invention. A person with ordinary skill in the art will also understand that such equivalent substitutions do not depart from the spirit and scope of the present invention, and that modifications, substitutions, or alterations may be made insofar as they do not depart from the spirit and scope of the present invention.

Claims

1. A polishing composition having a surface modified with a silane coupling agent, possessing a positive surface potential, an average secondary particle diameter of 45 nm or more and 100 nm or less, and a silanol group density of 0.0 / nm. ２ Larger than 3.0 particles / nm ２ The following abrasive grains, A surfactant which is an alkyl phosphate with 6 to 18 carbon atoms, Aqueous dispersion medium and A polishing composition containing the following:

2. The polishing composition according to claim 1, further comprising a pH adjusting agent.

3. The polishing composition according to claim 2, wherein the pH adjusting agent is a carboxylic acid (excluding amino acids) or an amino acid.

4. The polishing composition according to claim 3, wherein the carboxylic acid has an even number of carbon atoms.

5. The polishing composition according to claim 3, wherein the amino acid is an acidic amino acid.

6. The polishing composition according to claim 1, wherein the pH value of the polishing composition is in the range of 3 to 5.

7. The polishing composition according to claim 1, wherein the concentration of the surfactant is 0.1 to 1.0 g / L.

8. The polishing composition according to claim 1, wherein the abrasive grains are modified with a silane coupling agent having an amino group.

9. The polishing composition according to claim 8, wherein the silane coupling agent is (3-aminopropyl)triethoxysilane (APTES).

10. A polishing method, The steps include preparing a polishing apparatus including a polishing pad and a polishing head, The steps include setting the object to be polished between the polishing pad and the polishing head, A step of polishing the object to be polished using the polishing composition described in any one of claims 1 to 9, Polishing methods including those mentioned.

11. The object to be polished is a substrate including a first surface that faces the polishing head and is the outermost surface, and a second surface located below it. The polishing method according to claim 10, wherein at least a metal nitride is present on the second surface of the substrate.

12. The polishing method according to claim 11, wherein the metal nitride includes titanium nitride (TiN).

13. A method for manufacturing a semiconductor substrate, comprising the polishing method described in claim 10.

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